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1 國立臺北科技大學機械系 實務專題論文 筆記型電腦樞軸材料性質測試 & 雷射二極體的反光鍍膜 PC Hinge Materials Testing and AR Laser Diode Coating 專題製作學生: 四機四丙 Jorge Eduardo Sanchez 何仁德 97307451 指導教授: 莊賀喬博士 Prof. Ho-Chiao Chuang, Ph.D. 中華民國一百一年十一月二十六日

PC Hinge Materials Testing and AR Laser Diode Coating

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Original thesis submitted to the department of Mechanical Engineering, National Taipei University of Technology in partial fulfillment of the requirements for the degree of Bachelor of Science.

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Page 1: PC Hinge Materials Testing and AR Laser Diode Coating

1

國立臺北科技大學機械系

實務專題論文

筆記型電腦樞軸材料性質測試 amp 雷射二極體的反光鍍膜

PC Hinge Materials Testing and AR Laser Diode Coating

專題製作學生 四機四丙

Jorge Eduardo Sanchez 何仁德

97307451

指導教授 莊賀喬博士

Prof Ho-Chiao Chuang PhD

中華民國一百一年十一月二十六日

2

ABSTRACT

Project Name PC Hinge Materials Testing and AR Laser Diode Coating

School National Taipei University of Technology Mechanical Engineering Department

Graduation Time June 2012 Degree Bachelor in Science

Student Name Jorge Sanchez Advisor Prof Ho-Chiao Chuang

Keywords Hinge Youngrsquos modulus Poisson ratio material properties Boson

Bose-Einstein Condensate Reflectivity

The focus of this independent study research is divided into two The first was done in

National Taipei University of Technology Mechanical Engineering Department under the

guidance of Prof Ho-Chiao Chuang while the second was done in joint research with Institute

of Atomic and Molecular Sciences Academia Sinica from Taiwan under the guidance of Prof

Ho-Chiao Chuang and Dr Ming-Shien Chang PhD

In response that new generation computers are gradually reducing their size the diameter of

the structures of the hinges used by NB computers must also follow but the hinge strength may

also become smaller due to the reduction of diameter and result in the phenomenon of

insufficient strength In addition the disk-type spring that is source of the torque may also be

insufficient due to the narrowing of the structure Therefore it is necessary to direct a structural

analysis of the hinge for the existing laptops so that we can identify the stress concentration

point The stress concentration point is usually the point where material damage behavior is

encountered the easiest and if we can find the point where breaking occurs most often we can

improve the design of the existing structure to enhance the strength of the hinge structure

Second the structure of the hinge is too complicated the traditional mechanics of materials

analysis methods and formulas are no longer suitable for analysis of a wide arrange of hinge

design In recent years finite element analysis methods have been widely applied in various

fields such as electronics machinery aviation and so on

Therefore one of this independent study projectrsquos focus is to test hinge materials

acquired from cooperate manufacturers by means of tensile testing and then obtain the materials

3

special properties such as Youngrsquos modulus Poisson ratio yield strength tensile strength and

so on The experimental results may be entered into the subsequent finite element analysis

software the objective is to enter the materialrsquos real parameters to make the structural analysis

simulation more realistic

The 2nd

focus of this independent study is to help in the further research of the

Bose-Einstein condensate This is a state of matter of a dilute gas weakly interacting bosons

(subatomic particles that obey the Bose-Einstein statistics) confined in an external potential and

cooled down to temperatures very near absolute zero (0 K or -27315deg C) Under these conditions

a large number of bosons occupy the lowest quantum state of the external potential at which

point quantum effects become apparent at macroscopic scale This state of matter was predicted

by Satyendra Nath Bose and Albert Einstein in 1924~1925 Then 70 years later the 1st gaseous

condensate was produced by Eric Cornell and Carl Wieman in 1995 at the University of

Colorado (Boulder) NIST-JILA lab and because of this along with Wolfgang Ketterle of MIT

they received the 2001 Nobel Prize in Physics

We designed and have constructed a vacuum chamber where Anti Reflecting Coating will be

applied to laser diodes in order to reduce the reflectivity of the laser diodersquos surface to make

effective the injection lock This creates a desired wavelength of light inside a laserrsquos pumping

medium and may reduce surface reflection coefficient to less than 01 We expect to obtain

certain desired working properties after this process which will allow us to continue our project

We hope that through our research we can find significant applications to this theory

4

ACKNOWLEDGEMENT

First and foremost I would like to thank God I would never have done this study without the

faith I have in you the Almighty

I would like to thank my parents Gloria Iveth Sanchez and Juan Carlos Bonilla my sisters

Joanna Iveth Bonilla Karla Ines Bonilla and Kelly Gabriela Bonilla and my entire family for

their love support patience and understanding during my 5 years of studying abroad

I owe my deepest gratitude to my advisor Professor Ho-Chiao Chuang PhD for letting me

carry out this study Without his support and comprehension this study would have never been

carried out

Special thanks to Institute of Atomic and Molecular Sciences Academia Sinica Dr

Ming-Shien Chang for without him I would not be able to understand and put into practice

some of the principles presented in this thesis

I am indebted to many friends and classmates for the invaluable support during my studies in

this country and in this University

A special mention to my beloved friends Christian Reyes Francisco Garcia Jose Pagoada

and Olvin Castillo to my classmates 姚呈忠 王煜璨 林炯宇 for helping me during my tough

times my senior 廖梃君 and my junior 石中鈺 for thanks to them I was able to work and

present results during the course of this research and everyone else involved at the Department

of Mechanical Engineering at National Taipei University of Technology

5

TABLE OF CONTENTS

ABSTRACThelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 2

ACKNOWLEDGEMENThelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 4

TABLE OF CONTENTShelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 5

LIST OF TABLEShelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 7

LIST OF FIGUREShelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 8

CHAPTER 1 Introductionhelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 10

11 Motivation and Backgroundhelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 10

12 Research Objectivehelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 11

13 Methodologyhelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 13

14 Organization of the Thesishelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 13

CHAPTER 2 Basic Principleshelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 14

21 Tensile Testinghelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 14

211 Youngrsquos Modulushelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 14

212 Yield Strength and Yield Pointhelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 15

213 Ultimate Tensile Strength and Breaking Strengthhelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 16

214 Poissonrsquos Ratiohelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 16

215 Strain Gauge Basic Principleshelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 16

22 Hardness Test Basic Principleshelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 18

221 Brinell Scale BHNhelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 18

222 Rockwell Scale HRhelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 19

223Vickers Hardness Test HVhelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 21

23 AR Coatinghelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 22

231 Bose-Einstein Condensatehelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 22

232 AR Coating Basic Principleshelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 25

233 Laser Diode Basic Principleshelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 28

234 Quartz Microbalance Systemhelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 29

235 Vacuum Chamber Systemhelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 38

CHAPTER 3 Tensile Testing in depthhelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 41

31 Experimentrsquos Purpose and Principleshelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 41

32 Experimentrsquos Equipmenthelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 41

321 Universal Testing Machinehelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 41

322 Strain Measurement Equipmenthelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 43

6

323 Strain Gaugehelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 45

324 Specimen Measurementshelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 47

33 Experiment Procedurehelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 47

34 Resultshelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 54

341 SUM 23helliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 55

342 SUM 43helliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 67

CHAPTER 4 AR Coating in depthhelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 77

41 Experimentrsquos Purpose and Principleshelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 77

42 Experimentrsquos Equipmenthelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 78

421 Vacuum Chamberhelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 78

422 Quartz Microbalancehelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 82

423 Turbo Pumphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 85

423 Multimeterhelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 88

43 Experiment Procedurehelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 89

44 Resultshelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 91

CHAPTER 5 Conclusions and Recommendationshelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 93

51 Conclusionshelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 93

52 Recommendationshelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 93

REFERENCEShelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 94

7

LIST OF TABLES

Table 2-1 Rockwell Hardness Test Scalehelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 20

Table 2-2 Z-Ratios for Different Materialshelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 33

Table 2-3 Classifications of Vacuumhelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 39

Table 3-1 Chun Yen Testing Machine Specshelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 42

Table 3-2 Vishay Micro-Measurements Model P3 Strain Indicator and Recorder Specshelliphelliphelliphelliphelliphellip 44

Table 3-3 Specifications for Round Barhelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 47

Table 3-4 Specifications for Strain Gaugehelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 48

Table 3-5 Mechanical Properties of SUM 23 Untreatedhelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 55

Table 3-6 Mechanical Properties of SUM 23 Nickelhelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 58

Table 3-7 Mechanical Properties of SUM23 Black Surface Materialhelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 63

Table 3-8 Mechanical Properties of SUM 43 Untreatedhelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 67

Table 3-9 Mechanical Properties of SUM 43 Nickelhelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 70

Table 3-10 Mechanical Properties of SUM 43 Black Surface Materialhelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 73

Table 4-1 Inficon SQM-160 RateThickness Monitor Specshelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 83

Table 4-2 Pfeiffer TCP 015 Electronic Drive Specshelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 85

Table 4-3 Granville Phillips 375 Convectron Vacuum Pressure Controller Specshelliphelliphelliphelliphelliphelliphelliphelliphellip 87

Table 4-4 Keithley Model 2000 6-12-Digit Digital Multimeter Specshelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 88

8

LIST OF FIGURES

Fig 1-1 Notebook Computer Hingehelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 11

Fig 1-2 Basic Structure of Laserhelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 11

Fig 1-3 Comparison between LED and Laser Diodehelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 12

Fig 1-4 External Cavity Designhelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 12

Fig 2-1 Stress-Strain Curvehelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 14

Fig 2-2 Stress-Strain Curve Comparison on Metalshelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 15

Fig 2-3 Basic Structure of Strain Gaugehelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 17

Fig 2-4 Strain Gauge Attached to Wheatstone Bridgehelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 18

Fig 2-5 Brinell Indentationhelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 18

Fig 2-6 Brinell Hardness Testerhelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 18

Fig 2-7 Rockwell Indentationhelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 19

Fig 2-8 Rockwell Hardness Testerhelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 19

Fig 2-9 Vickers Indentationhelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 22

Fig 2-10 Vickers Hardness Testerhelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 22

Fig 2-11 Bose-Einstein Condensate at different scaleshelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 23

Fig 2-12 Super Conductorhelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 24

Fig 2-13 Simple Model for Light in Glass Mediumhelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 25

Fig 2-14 Simple Model for Light in Glass Medium after AR Coatinghelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 26

Fig 2-15 Light Passing through AR Coating and Glasshelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 27

Fig 2-16 Lens without and with AR Coatinghelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 27

Fig 2-17 Laser Diodehelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 28

Fig 2-18 Tunable Laser Basic Configurationhelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 28

Fig 2-19 Light Spectrumhelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 29

Fig 2-20 Front and Back Panel of SQM-160helliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 29

Fig 2-21 QCM Crystalshelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 31

Fig 2-22 SQM-160 Oscillatorhelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 31

Fig 2-23 Oscillator Circuithelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 32

Fig 2-24 Vacuum Evaporation Systemhelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 39

Fig 2-25 Turbo Pumphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 39

Fig 2-26 Control and Measurement Equipmenthelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 40

Fig 2-27 Complete Systemhelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 40

Fig 3-1 Universal Testing Machinehelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 41

Fig 3-2 Diagram for System Connectionshelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 42

Fig 3-3 Input Connections for Strain Gaugehelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 43

Fig 3-4 Vishay Micro-Measurements Model P3 Strain Indicator and Recorderhelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 43

Fig 3-5 Inner Connectionshelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 45

Fig 3-6 Tensile Specimenhelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 47

Fig 3-7 Actual Tensile Specimenhelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip47

Fig 3-8 Other Materials Usedhelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 48

Fig 3-9 Specimen-Strain Gauge Processhelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 49

Fig 3-10 Specimen-Tensile Testing Processhelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 53

9

Fig 3-11 SUM 23 Untreated Materialhelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 55

Fig 3-12 Stress-Strain Diagrams for 7 and 10 Round Barhelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 56

Fig 3-13 Cut-Off Area of 7 and 10 Round Barhelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 57

Fig 3-14 SUM 23 Nickel Materialhelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 58

Fig 3-15 Stress-Strain Diagrams for 1 2 3 and 4 Round Barhelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip60

Fig 3-16 Cut-Off Area of 1 2 3 and 4 Round Barhelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 62

Fig 3-17 SUM 23 Black Surface Materialhelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 63

Fig 3-18 Stress-Strain Diagrams for 1 2 and 3 Round Barhelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 65

Fig 3-19 Cut-Off Area of 1 2 and 3 Round Barhelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 66

Fig 3-20 SUM 43 Untreated Materialhelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip67

Fig 3-21 Stress-Strain Diagrams for 1 and 5 Round Barhelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 68

Fig 3-22 Cut-Off Area of 1 and 5 Round Barhelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 69

Fig 3-23 SUM 43 Nickel Materialhelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 70

Fig 3-24 Stress-Strain Diagrams for 4 and 5 Round Barhelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 71

Fig 3-25 Cut-Off Area of 4 and 5 Round Barhelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 72

Fig 3-26 SUM 43 Black Surface Materialhelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 73

Fig 3-27 Stress-Strain Diagrams for 3 and 5 Round Barhelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 74

Fig 3-28 Cut-Off Area of 3 and 5 Round Barhelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 75

Fig 4-1 BEC Apparatushelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 77

Fig 4-2 Vacuum Chamber Main Bodyhelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 78

Fig 4-3 Thermocouplehelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip79

Fig 4-4 Filament Boat Clamp Designhelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 79

Fig 4-5 Cover Assemblyhelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 80

Fig 4-6 Upper Cover Inner Assemblyhelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 80

Fig 4-7 Diagram of Upper Cover Connectionshelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 81

Fig 4-8 Feed Through Diagramhelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 81

Fig 4-9 Fully Assembled Chamberhelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 82

Fig 4-10 Inficon SQM-160helliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 82

Fig 4-11 Sigma Instruments Remote Oscillatorhelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 84

Fig 4-12 SQM-160 Connections Diagramhelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 84

Fig 4-13 Pfeiffer TCP 015 Electronic Drivehelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 85

Fig 4-14 Connections Diagram for Pfeiffer TCP 015helliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 86

Fig 4-15 Granville Phillips 375 Convectronhelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 86

Fig 4-16 Dimensions of Convectronhelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 87

Fig 4-17 Keithley Model 2000 6-12-Digit Digital Multimeterhelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 88

Fig 4-18 Checking for Leaks Using Alcoholhelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 89

Fig 4-19 Convectron Attached to Systemhelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 89

Fig 4-20 Multimeter Connectionshelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 90

Fig 4-21 Simulation Modehelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 90

Fig 4-22 AR Coating Comparison for Laser Diodeshelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 91

Fig 4-23 Before AR Coatinghelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 92

Fig 4-24 After AR Coatinghelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 92

10

Chapter 1 INTRODUCTION

11 Motivation and Background

In response that new generation computers are gradually reducing their size the diameter of

the structures of the hinges used by NB computers must also follow but the hinge strength may

also become smaller due to the reduction of diameter and result in the phenomenon of

insufficient strength In addition the disk-type spring that is source of the torque may also be

insufficient due to the narrowing of the structure Therefore it is necessary to direct a structural

analysis of the hinge for the existing laptops so that we can identify the stress concentration

point The stress concentration point is usually the point where material damage behavior is

encountered the easiest and if we can find the point where breaking occurs most often we can

improve the design of the existing structure to enhance the strength of the hinge structure

Second the structure of the hinge is too complicated the traditional mechanics of materials

analysis methods and formulas are no longer suitable for analysis of a wide arrange of hinge

design In recent years finite element analysis methods have been widely applied in various

fields such as electronics machinery aviation and so on

Therefore to meet the need of the industry and with the purpose of reducing design time

how to design a notebook computer hinge without compromising mechanical stability and

materialrsquos hardness which will operate equally under equal conditions In other words be able to

meet the needs of the size decreasing NB computers market as the needs for this kind of

accessories will increase in the near future If we take into consideration the traditional ways of

design we seek to reduce the costs of use of machinery and molding by applying Finite Element

Analysis methods to our study and also increase the flexibility of designing methods

The second project was brought in by Prof Chuang and it is to help in the further research of

the Bose-Einstein condensate This is a state of matter of a dilute gas weakly interacting bosons

(subatomic particles that obey the Bose-Einstein statistics) confined in an external potential and

cooled down to temperatures very near absolute zero (0 K or -27315deg C) Under these conditions

a large number of bosons occupy the lowest quantum state of the external potential at which

point quantum effects become apparent at macroscopic scale This state of matter was predicted

by Satyendra Nath Bose and Albert Einstein in 1924~1925 Then 70 years later the 1st gaseous

condensate was produced by Eric Cornell and Carl Wieman in 1995 at the University of

Colorado (Boulder) NIST-JILA lab and because of this along with Wolfgang Ketterle of MIT

they received the 2001 Nobel Prize in Physics

11

We wish to investigate the properties of Anti Reflecting Coating on laser diodes Hopefully

we will be able to achieve the desired effect of reducing the surface reflection coefficient and

find applications for it

12 Research Objective

We wish to analyze the normal composition of the notebook computerrsquos hinge at which

point in the assembly is clearly the weakest and at this time in the assembly the strength and

durability are influenced The main point is to see if we can affect the normal operation and work

life

The objective of this thesis is to present the results of the material properties under tensile

testing find the mechanical properties and after using finite element analysis determine what

material is the best for our purposes

Fig 1-1 Notebook Computer Hinge

For our second research we wish to produce and analyze laser diodes with anti-reflective

coating and test its properties and applications

When semi-conductor laser has been submitted to current it will produce resonance inside it

and light will be stimulated to come out Please refer to figure 1-2 for the basic structure of a

laser

Fig 1-2 Basic Structure of a Laser

1 Gain Medium

2 Laser Pumping Energy

3 High Reflector

4 Output Coupler

5 Laser Beam

12

But when the laser diode generates light but the laser diode canrsquot produce light on itself it

must wait for the current to be higher than certain value which is called the critical current Until

the light goes over this threshold then it is considered laser light if not it is just considered as a

common LED light source Please refer to figure 1-3

Fig 1-3 Comparison between LED and Laser Diode

As we can see from figure 1-3 all of the light that goes over the critical current is laser light

and so the external cavity semi-conductor laser that we built needs Anti-Reflective Coating

because the method we want to use needs an external cavity laser that has been covered with AR

Coating and a Diffraction Grating We use this configuration first by shooting the laser to the

grating and this will be shot back to the laser creating the external resonance cavity which is

shown in figure 1-4

Fig 1-4 External Cavity Design

13

Two configurations are shown the Littrow Configuration and the Littman-Metcalf

Configuration The Littrow configuration contains a collimating lens and a diffraction grating as

the end mirror The first order diffracted beam provides optical feedback to the laser diode which

has AR Coating The emission wavelength can be turned by rotating the diffraction grating A

disadvantage is that it also changes the direction of the output beam

In the Littman-Metcalf configuration the grating orientation is fixed and an additional mirror

is used to reflect the first order beam back to the laser diode The wavelength can be turned by

rotating that mirror This configuration offers a fixed direction of the output beam and also tends

to exhibit smaller line width as the wavelength selectivity is stronger A disadvantage is that

zero order reflection of the beam reflected by the tuning mirror is lost so that the output power is

less than that of a Littrow laser

13 Methodology

The aim of this research is to find the mechanical properties of materials after being

subjected to tensile testing through finite element analysis observations and determine what

material is best for our purposes taking into consideration the strength and durability of the

material among other properties to find use and applications for the AR coated laser diodes to

further improve the grasp of the Bose-Einstein condensation working principles

14 Organization of the Thesis

The research paper includes five chapters

1 Chapter 1 explains the motivation background objective and methodology of this study

2 Chapter 2 explains the working principles and basic knowledge needed to understand this

study

3 Chapter 3 explains the tensile testing in detail steps methods and results

4 Chapter 4 explains the AR coating in detail steps methods and results

5 Chapter 5 is the conclusions taken from the results shown in chapter 3 and 4 and

recommendations done after arranging and critical thinking

14

Chapter 2 BASICS THEORIES

21 Tensile Testing

After a specimen is tested with the use of tensile testing we can get the Stress-Strain Curve using the

relation between tension and displacement Typical curves are shown in Fig 2-1

(a) Ductile materials (b) Brittle materials

Fig 2-1 Stress-Strain Curve

The curve is unique for each material and is found by recording the amount of deformation at distinct

intervals of tensile or compressive loads Thanks to the use of the Stress-Strain curve we can get very

useful information such as

211 Youngrsquos Modulus (E)

As shown in Fig 2-1 as long as the external load is not greater than the Proportional Limit the Stress

(σ) and Strain (ε) remain as a linear relation fulfilling Hookersquos Law

σ = Eε

The slope is the constant factor the inverse of the modulus of elasticity E also called Youngrsquos

modulus When the external load goes over the proportional limit the stress-strain relationship doesnrsquot

follow the linear relation anymore but the deformation remains flexible When the load is released the

deformation is completely eliminated and the specimen goes back to its original state This is called

15

Elastic Deformation When the external load goes over the Elastic limit only then does the specimen

presents Plastic Deformation This type of deformation which is irreversible even when the load is

removed comes after the material does under elastic deformation so this means the object will first come

part way to its original shape Common metals and ceramics have roughly the same elastic limits

212 Yield Strength and Yield Point

Some materials display very evident yield phenomena while some materials donrsquot as shown in Fig

2-2 After we exceed the elastic limit if we continue to exert load when we arrive to a certain value

which differs under different materials and external conditions there is sudden decrease in stress and this

is called the Yield Strength and can be defined as the stress at which a material begins to deform

plastically using the equation

σyield =

Where P is the tension force and Ao is the original cut-off area

The stress remain at a certain value after the decrease but the strain increases this phenomena can be

easily appreciated when studying the behavior of common Carbon Steel Fig2-2 (a) but most metals (like

Aluminum Copper or High Steel Carbon) donrsquot display this kind of behavior as shown in Fig 2-2 (b)

Arriving to this point is very difficult and the most commonly used method for this is to add a 02 or

0002 offset yield strength to the curve This point is held constant on the strain axis of the curve and

from the 0002 position we draw a straight line parallel to the linear relationship line the point at where

this line and the stress-strain curve intercept is the point we take as the 02 offset yield strength

(a)Evident (b) Non-evident

Fig2-2 Stress-Strain Curve Comparison on Metals

16

213 Ultimate Tensile Strength and Breaking Strength

After materials undergo yield they keep lending strength and hardening phenomena occurs (work

hardening) on the material and the external load increases When it has reached the highest point this is

called the Ultimate Tensile Strength (UTS) as shown in Fig2-1 The UTS is defined as

σUTS =

Where Pmax is the load at the materialrsquos ultimate tensile strength point and Ao is the original cut-off

area For brittle materials the ultimate tensile strength is the most important mechanical property for

ductile materials the ultimate tensile strength is not commonly used for industrial and designing purposes

because upon arriving to this value the material already has forgone great plastic deformation After the

specimen goes through UTS there will be necking phenomena which is a mode of tensile deformation

where relatively large amounts of strain localize disproportionately in a small region of the material It

results from instability during tensile deformation when a materialrsquos cross-sectional area decreases by a

greater proportion than the material strain hardens The specimen continues to elongate until it finally

breaks and the load at this point is called Breaking Strength The breaking strength is defined as the

greatest stress in tension that a material is capable of withstanding without rupture

Where Pf is the load at the materialrsquos breaking strength point and Ao is the original cut-off area

214 Poissonrsquos Ratio (ν)

For elastic deformation when materials are compressed in one direction they tend to expand in the

other two directions perpendicular to the direction of compression This is called the Poissonrsquos Effect

The Poison Ratio is a measure of the Poissonrsquos effect It is the ratio of the fraction of expansion divided

by the fraction of compression for small values of these changes

ν=-

215 Strain Gauge Basic Principles

The strain gauge is a device used to measure the strain of an object Itrsquos an elongated metal resistor

which is attached to the specimen being measured and when the specimen is under strain and starts to

deform the strain gauge will have a change in the resistance With the change in value we can calculate

the elementrsquos strain or elastic modulus and the Poissonrsquos ratio

It takes advantage of the physical property of electrical conductance and its dependence on the

conductorrsquos geometry When the electrical conductor (the specimen being tested) is stretched within the

limits of elasticity such that it does not break or deform plastically it will become narrower and longer

17

which increases the electrical resistance through-out From the measured resistance of the strain gauge

the amount of stress may be inferred by using the relations

R=

Where R is the original resistance value is the electrical resistivity lo is the original length of the

conductor and Ao is the original cross sectional area of the conductor If after the application of tension

the change in length is Δl let the length of the specimen be l = l + Δlo and the tension is the same

through-out So

And the resistance is

The Gauge Factor is the ratio of relative change in electrical resistance to the mechanical strain in

other words it is the relative change in length It is defined as

The strain gauge was invented in 1938 by Edward E Simmons and Arthur C Ruge and the most

common type consists of an insulating flexible backing which supports a metallic foil usually made of a

brass-nickel alloy It is attached to the specimen by a suitable adhesive As the object is deformed the foil

also deforms and this causes the electrical resistance to change Then this is usually measured using a

Wheatstone bridge shown below and is related to the strain by the Gauge Factor

Fig2-3 Basic Structure of Strain Gauge

18

Fig 2-4 Strain gauge attached to Wheatstone bridge

22 Hardness Testing Basic Principles

221 Brinell Scale BHN

The Brinell Scale characterizes the indentation hardness of materials through the scale of penetration

of an indenter loaded on a material specimen The typical test uses a 10mm diameter steel ball as indenter

(usually of value equal to BHN450) with a 29kN force For softer materials smaller force is used The

indentation is measured and BHN is calculated using the relation

BHN =

radic

Where F is the applied force usually within the range of 100 250 500 750 1000 1500 2000 2500

and 3000 kgf D is the diameter of indenter usually within the range of 5mm or 10mm plusmn0005 margin

and d is the diameter of indentation usually around 2mm Its units are of Kgmmsup2 but are not normally

written

First proposed by Swedish engineer Johan August Brinell in 1900 it was the first widely used and

standardized hardness test in engineering and metallurgy although the large size of indentation and

possible damage to specimen limits its usefulness

Fig 2-5 Brinell Indentation Fig2-6 Brinell Hardness Tester

19

222 Rockwell Scale HR

The Rockwell scale is a hardness scale based on the indentation hardness of a material The Rockwell

test determines the hardness by measuring the depth of penetration of an indenter under a large load

compared to the penetration made by a preload The indenter is forced into the specimen under a

preliminary load When equilibrium is reached a measuring device follows the movements of the

indenter and responds to changes in depth of penetration of the indenter While the preload is still being

applied additional major load is applied resulting in increased penetration When equilibrium is reached

again the major load is removed but the preload is maintained Removing the major load allows partial

recovery and reduces the depth of penetration The permanent increase in depth of penetration resulting

from the application and removal of the major load is used to calculate the Rockwell number using the

relation

HR = E ndash e

Where E is a constant depending on the form of the indenter 100 units for diamond indenter and 130

units for steel ball indenter e is the permanent increase in depth of penetration due to the major load

measured in units of 0002mm

Fig 2-7 Rockwell Indentation

When testing materials indentation hardness is related linearly to the tensile strength The important

relation permits economically important nondestructive testing of bulk metal deliveries with lightweight

equipment like the Rockwell tester shown below in figure 2-7

Fig 2-8 Rockwell Hardness Tester

20

There are different scales denoted by a single letter that use different loads or different indenters

The result is a dimensionless number denoted as HR X where X will be the letter denoting the scale as

shown below in table 2-1

Table 2-1 Rockwell Hardness Test Scale

Differential depth hardness measurement was first conceived in 1908 by Viennese professor Paul

Ludwik It eliminated the errors associated with the mechanical imperfections of the system such as

backlash and surface imperfections in the specimen Rockwell testing has an advantage over Brinell

testing because the latter was slow itrsquos not useful on fully hardened steel and left too large an impression

to be considered nondestructive

The tester was co-invented by Hugh M Rockwell and Stanley P Rockwell The requirement for this

tester was to quickly determine the effects of heat treatment on steel bearing races

21

223 Vickers Hardness Test HV

This is a type of microindentation hardness test where a diamond indenter of specific geometry is

impressed into the surface of the test specimen using a known applied force ranging from 10 to 1000

grams This type of tests usually has forces of 2N and produce indentations of about 50μm They can be

used to observe changes in hardness on the microscopic scale It is difficult to standardize the

microhardness measurements because it has been found that the microhardness of almost any material is

higher than its macrohardness The values also vary with load and work-hardening effects of materials

The Vickers test is often easier to use than other hardness tests because the required calculations are

independent of the size of the indenter and the indenter can be used for all materials It can be used for all

metals and has one of the widest scales among hardness tests The unit of the Vickers test is denoted as

HV and can be converted to units of Pascal (Pa) but it is not a measurement of pressure The hardness

number is determined by the load over the surface area of the indentation and not the area normal to the

force

A square-based pyramid shaped diamond is use as the indenter It has been established that the ideal

size of a Brinell impression was 38 of the ball diameter As two tangents to the circle at the ends of a

chord 3d8 long intersect at 136plusmn05deg it was decided to use this as the angle of the indenter giving an

angle to the horizontal plane of 22deg on each side The HV number is determined by the ratio FA where F

is the force applied to the diamond in kgf and A is the surface area of the resulting indentation in mmsup2 A

can be determined by the relation

A =

Where A is the surface area of indentation and d is the average length diagonal left by the indenter

This can be approximated as

A =

Then the Vickers Number is

HV =

=

Vickers hardness number is reported as xxxHVyy or xxxHVyyzz (if duration of applied force differs

from 10s to 15s) where xxx are replaced by the hardness number yy is the load in kg and zz indicates

loading time The values are generally independent of test force

The test was developed in 1921 by Robert L Smith and George E Sandland at Vickers Ltd as an

alternative to Brinell method to measure the hardness of materials

22

Fig 2-9 Vickers Indentation Fig 2-10 Vickers Hardness Tester

23 AR Coating

231 Bose-Einstein Condensate

The Bose-Einstein Condensate or BEC is a state of matter of a dilute gas of bosons cooled to

temperatures very near absolute zero around 0K or -27315degC Under such conditions a large fraction of

the bosons occupy the lowest quantum state where the quantum effects become apparent on a

macroscopic scale This gave birth to the Bose-Einstein Statistics which are the rules that govern the

behavior at this state It is one of the two possible ways in which a collection of indistinguishable particles

may occupy a set of available discrete energy states The aggregation of particles in the same state

accounts for the cohesive streaming of laser light and the frictionless creeping of superfluid helium (an

application discussed later) Bose and Einstein recognized that a collection of identical and

indistinguishable particles can be distributed this way This theory applies only to those particles not

limited to single occupancy of the same state particles that do not obey the Pauli Exclusion Principle

restrictions Such particles are the Bosons named after the statistics that correctly describe their behavior

This phenomenon was first predicted by Satyendra Nath Bose around 1924 when he considered how

groups of photons behave He then asked Albert Einstein for help publishing his discoveries to which

Einstein agreed and gave follow up supporting these findings The resulting efforts became the concept of

a Bose gas governed by the Bose-Einstein Statistics described above Einstein demonstrated that cooling

bosonic atoms to a very low temperature would cause them to condense into the lowest accessible

quantum state resulting in a new form of matter

The first gaseous condensate we produced by Eric Cornell and Carl Wieman at the University of

Colorado at Boulder NIST ndash JILA lab sung a gas of rubidium atoms cooled to 170 nK which earned

them the 2001 Nobel Prize in physics together with Wolfgang Ketterle from MIT The transition to BEC

occurs below a critical temperature which for a uniform three dimensional gas consisting of

non-interacting particles with no apparent internal degrees of freedom is given by

23

Tc =

(

)

asymp 33125

Where Tc is the critical temperature n is the particle density m is the mass per boson h is the

reduced Planck constant k is the Boltzmann constant and ζ is the Riemann zeta function

There are two classes of elementary particles defined by whether their quantum spin is a nonnegative

integer or an odd half integer A Bose-Einstein Condensate is shown below in figure 2-11

Fig 2-11 Bose Einstein Condensate at different scales

Bosons are the particles whose quantum spin is a nonnegative integer (s = 0 1 2 etc) Examples of

bosons include fundamental particles (Higgs Boson Photons W and Z Bosons Gluons Gravitons etc)

composite particles (Mesons Hadrons Nuclei and Atoms of Carbon-12 and Helium-4) and

quasi-particles Bosons are considered force carrier particles The Bosons differ from Fermions in that

there is no limit to the number that can occupy the same quantum state This is called the Pauli Exclusion

Principle

The Pauli Exclusion Principle says that no two identical fermions may occupy the same quantum state

simultaneously in other words this means that the total wave function for two identical fermions is

anti-symmetric with respect to exchange of the particles This means that no two electrons in a single

atom can have the same four quantum numbers

Fermion is any particle characterized by Fermi-Dirac Statistics and follows the Pauli Exclusion

Principle described above Quarks Leptons and composite particles (Hadrons Nuclei and Atoms of

Carbon-13 and Helium-3) made of an odd number of these are considered Fermions It can be an

elementary particle such as the electron or a composite particle such as the protons Following the Pauli

24

Exclusion Principle only one fermion can occupy a particular quantum state at any given time If multiple

fermions have the same spatial probability distribution then at least one property of each fermion must be

different Fermions are usually associated with matter because composite fermions are key building

blocks of matter (neutrons and protons)

Fermionsrsquo behavior by the Fermi-Dirac Statistics which describes the energies of single particles in a

system comprising of many identical particles It applies to identical particles with half-odd integer spin

in a system of thermal equilibrium The particles in the system are assumed to have negligible mutual

interaction This allows the many-particle system to be described in terms of single-particle energy states

The result is the Fermi-Dirac distribution of particles over these states and includes the condition that no

two particles can occupy the same state which has considerable effect on the properties of the system

In quantum mechanics the position of an object is uncertain An object has a definite probability of

being at any given point in space This probability is encoded in the wave function mentioned earlier If

one concentrates a large number of identical bosons in a small region then it is possible for their wave

functions to overlap so much that the bosons lose their identity When this happens thatrsquos a Bose-Einstein

Condensate It is only possible at very low temperatures because at high temperatures the individual

bosons have small wave functions and move rapidly which causes them to fly apart

For now applications are still restricted because there are still some setbacks regarding BECs They

are extremely fragile they are being produced in small quantities with just a few million atoms at a time

and finally they can only be made from certain types of atoms Some examples are the atom laser Ketterle

in which a conventional light lase emits a beam of coherent photons this means they are all in phase and

can be concentrated to an extremely small bright spot BECs can slow down light as demonstrated by

Prof Lene Hau PhD in 2001 by the use of a superfluid [7] These manipulations could develop into

new types of telecommunications technology optical storage and quantum computing

BECs are related to super-fluidity and super-conductivity Super-fluidity is the state of matter in

which the behavior is that of a fluid with zero viscosity It was discovered in liquid helium but now it has

applications in astrophysics high-energy physics and theories of quantum gravity

Super-conductivity is a phenomenon of exactly zero electrical resistance and expulsion of magnetic

fields occurring in certain materials when cooled below a characteristic critical temperature A

super-conductor is shown below in figure 2-12

Fig2-12 Super Conductor

25

232 AR Coating Basic Principles

Anti-reflective (AR) coating is a type of optical coating applied to the surface of lenses and other

optical devices (in our case we planned to apply it to a laser diode) to reduce reflection This improves

the efficiency of the system since less light is lost The primary benefit is the elimination of the reflection

itself

When light the medium (glass) it will produce reflection if 100 of the light comes from the air and

enters the glass because therersquos a difference between the index of refraction some of the light will go out

and when the light is coming out of the glass into the air once again because of the difference between

index of refraction some of the light wonrsquot be able to pass through the medium

When the light makes the first trip into the glass there was a loss of about 4 in the reflection and

when the light makes the trip back outside there was another loss of about 4 so when we assume that

100 of the light interacts with the medium actually therersquos just about 92 acting (we neglect the light

absorbed by the glass around 05) To illustrate this idea please refer to figure 2-13

Fig 2-13 Simple Model for Light in Glass Medium

When we apply the AR Coating the light that enters will only have a loss of about 05 and when

making the trip back outside again only 05 of light is loss so we get the result of increasing the light

passing through up to 99 (again neglecting the light absorbed by the glass around 05) To illustrate

this idea please refer to figure 2-14

26

Fig 2-14 Simple Model for Light in Glass Medium after AR Coating

The AR Coating can reduce reflection of incoming light In the case that light hits perpendicular to

the surface of the medium the intensity of the reflection can be calculated using the Reflection

Coefficient

Where n0 and ns are the refractive indices of the first and second media respectively The value of R

varies from 0 (no reflection) to 1 (all light reflected) and is usually quoted as a percentage

Complementary to R is the transmission coefficient or Transmittance If absorption and scattering are

neglected then the value of Transmittance is always 1-R then if a beam of light with intensity I is

incident on the surface a beam of intensity RI is reflected and a beam with intensity TI is transmitted to

the medium

The optimal value is called the Optimal Index of Refraction and is described as

For glass with ns around 15 in air (n0 around 10) then the optimum refractive index will be n1 =

1225

To reduce the refraction in this case we now mean the one that is produced inside the chamber of the

Laser diode the easiest way is to apply a low reflectivity AR coating on the surface of the laser To

measure the appropriate thickness of the coating layer we can use the equations described above By

applying a coat exactly

thickness film we can assure that a certain wavelength is transmitted The

27

reflected waves from the back of the glass medium will be half a wavelength out of phase So they

interfere destructively Because all reflected waves are interfered the maximum amount of light passes

through the coating Please refer to figure 2-15 to illustrate this idea

Fig 2-15 Light Passing through AR Coat and Glass

The most common process to attain this final product is by vacuum deposition For the best coating

results we need to lower the pressure inside the vacuum system to torr

Fig 2-16 Lens without (Top) and With (Bottom) AR Coating

28

233 Laser Diode Basic Principles

A laser diode is a laser whose active medium is a semiconductor similar to that found in

light-emitting diodes (LEDs) Please refer to figure 2-17 The most common type of laser diode is formed

from a p-n junction and powered by injected electric current

Fig 2-17 Laser Diode

Laser diodes are formed by doping a very thin layer on the surface of a crystal wafer The crystal is

doped to produce the n-type region and a p-type region one above the other

By referring to figure 1-2 we can see the basic structure of a working laser When the laser diode has

a current passing through it the light will get excited inside its gain medium and then will start to

resonate this process is called pumping The current exceeds the critical current and then it comes out as

laser light Please refer to figure 1-3 Since we use an external cavity laser we need to apply the AR

coating to the diode and adjust a diffraction grating The laser light comes out the diode and bounces on

the grating making the resonance externally and this becomes the ldquocavityrdquo as shown in figure 2-18

Fig 2-18 Tunable Laser Basic Configuration

29

The most important feature of the external cavity laser is that we can adjust the wavelength easily just

by changing the diffraction gratingrsquos angle and in the end this is the output wavelength of the laser For

different wavelengths there will be different levels of visible light as shown in figure 2-19

Fig 2-19 Light Spectrum

234 Quartz Microbalance System

A Quartz Crystal Microbalance is an instrument that measures a mass per unit area by measuring the

change in frequency of a quartz crystal resonator The resonance is disturbed by the addition or removal

of a small mass due to oxide growthdecay or film deposition (which is the case in our study) at the

surface of the acoustic resonator The QCM can be used under vacuum in gas phase and more recently in

liquid environments It is useful for monitoring the rate of deposition in thin film deposition systems

under vacuum Frequency measurements are easily made with high precision

For our research we used the Sigma Instruments SQM-160 RateThickness Monitor shown in figure

2-20

Fig 2-20 Front and Back Panels of SQM-160

30

The microbalance uses Quartz as the resonator Quartz is one member of the family of crystals that

experience the Piezoelectric Effect

Piezoelectricity is the charge that accumulates in certain solid materials in response to applied

mechanical stress It means electricity resulting from pressure It was discovered in 1880 by Jacques and

Pierre Curie It is understood as the linear electromechanical interaction between the mechanical and the

electrical state in crystalline materials with no inversion symmetry It is a reversible process in that

materials exhibiting direct piezoelectricity also exhibit the reverse This means that the internal generation

of electrical resulting from applied mechanical force and vice versa

By using the piezoelectric effect we can probe as an acoustic resonance by electrical means Applying

alternating current to the quartz crystal induces oscillations This creates a shear wave We can use these

qualities to determine the resonance frequency at high accuracy

The frequency of oscillation of the crystal is partially dependent in the thickness of the crystal During

normal operation all the variables are held constant so a change in thickness correlates directly to a

change in frequency As mass is deposited or etched away the thickness increases or decreases and so the

frequency of oscillation changes accordingly With some simplifying assumptions the frequency change

can be quantified and correlated precisely to the mass change using the Sauerbreyrsquos Equation

Developed by G Sauerbrey in 1959 it is a method for correlating changes in the oscillation

frequency of a piezoelectric crystal with the mass deposited on it It is defined as below

Where f0 is the Resonant frequency Δf is the Frequency change Δm is the mass change A is the

piezoelectrically active area of the crystal q is the Density of quartz (2648 gcmsup3) and μq is the Shear

modulus of quarts(2947x gcmssup2)

Because the film is treated as an extension of thickness Sauerbreyrsquos equation only applies to systems

in which the following 3 conditions are met

Deposited mass must be rigid

Deposited mass must be distributed evenly

The frequency change

lt002

If the change is greater than 2 the Z-match method must be used to determine the change in mass

It is defined as

Where fL is the frequency of the loaded crystal fU is the resonant frequency Nq is the frequency

constant (1668x HzAring) Δm is the mass change A is the piezoelectrically active area of the crystal

31

q is the density of quartz Z is the method constant f is the density of film μq Is the shear modulus of

quarts and μf is the shear modulus of film

The Sauerbrey equation cannot be applied to systems under liquid medium

The crystals are seed crystals plated with gold on both top and bottom for applications A crystal is

shown in figure 2-21 The QCM consists of a thin piezoelectric plate with electrodes evaporated on both

sides Due to the piezoelectric effect AC voltage across the electrodes induces a shear deformation and

vice versa The electromechanical coupling provides a simple way to detect an acoustic resonance by

electrical means

The Z also called Z-factor is a constant value for different materials and it is shown together with the

density of different materials in table 2-2 below

Fig 2-21 QCM Crystals

The Oscillator of the SQM-160 is shown in figure 2-22 and the equivalent circuit for the Resonant

Oscillator is shown in figure 2-23

Fig 2-22 SQM-160 Oscillator

32

Fig 2-23 Oscillator Circuit

33

Table 2-2 Z-Ratios for Different Materials

Table 2-2 Continued

34

Table 2-2 Continued

35

Table 2-2 Continued

36

Table 2-2 Continued

37

Table 2-2 Continued

38

Table 2-2 Continued

235 Vacuum Chamber System

Vacuum Evaporation is the process of depositing thin films of materials onto surfaces The technique

consists of pumping a vacuum chamber to pressures of less than torr and heating a material to

produce a flux of vapor in order to deposit the material onto a surface The material to be vaporized is

typically heated until its vapor pressure is high enough to produce a flux several Angstrom per second by

using an electrically resistive heater or bombardment by a high voltage beam The process was invented

by Henri Nestle in 1886 for food industry

In here the system has been pumped to a vacuum of Torr When a high current is passed

through the filament boat the filament boat is heated over the desired metal evaporation temperature and

so evaporation starts When the evaporation process is finished and the metal cools down crystals

condensate in the surface of the wafer From the weight of the evaporated material the distance between

the filament boat and the wafer we are able to calculate the deposition thickness and we can also use the

mass detector follower like the Quartz crystal resonator microbalance system In the process of

evaporation we usually use a board in between the filament boat and the wafer This is because before we

arrive to the desired evaporation temperature there will be some impurities that will be vaporized in the

controlled environment so we first use a small current and the board in between to get rid of those

impurities and this raises the purity of the deposition material

39

A vacuum evaporation system is shown in figure 2-24

Fig 2-24 Vacuum Evaporation System

Rough Vacuum 760 ~ 1 torr

Medium Vacuum 1 ~ torr

High Vacuum ~ torr

Ultra-High Vacuum Lower than torr

Table 2-3 Classification of Vacuum

For our study we need to use a Turbo Pump A regular turbo pump is shown in figure 2-25

Fig 2-25 Turbo Pump

For our research we used the Pfeiffer TCP 015 Electronic Drive Unit and Granville Phillips 375

Convectron shown below in figure 2-26

40

Fig 2-26 Control and Measurement Equipment

The electronic drive controls the turbo pump and the Convectron measures the pressure inside our

chamber The turbo pump is a type of vacuum pump used to maintain high vacuum Most turbo pumps

are centrifugal When we start the pumping we need to use a mechanical pump so as to decrease the

pressure inside the system from constant atmospheric pressure to torr and then the use dispersion

pump to continue the vacuum until we get to the desired pressure We need to notice though when we

start the dispersion pump we canrsquot turn off the mechanical pump and they both need to run together If

we need to turn off the pumping we first turn off the dispersion pump wait for it to completely stop and

then turn off the mechanical pump

Our completely assembled system is shown in figure 2-27 below

Fig 2-27 Complete System

41

Chapter 3 TENSILE TESTING IN DEPTH

31 Experimentrsquos Purpose and Principles

By means of Universal testing machine and Strain gauges we were able to observe discuss and

analyze the phenomena created when a specimen of certain material is manipulated under an external load

and determine the stress strain and deformation values later we can use the graphing methods of

stress-strain diagram to describe it

The main point of this experiment is that after the tensile specimen is tested use computer analysis

and the actual strain data and after statistical adjustment make the final results report (Tensile testing

experiment is in accordance with ASTM E8)

32 Experimentrsquos Equipment

321 Universal Testing Machine

For the materials testing experiment part of this research we use a Universal Testing Machine as

shown in figure 31 The maximum load it can apply is 100 Ton After the test specimen is secured on the

device with the use of instrumentation the load exerted and the effects of this become apparent on the

specimen and even the smallest of changes can be recorded For our research we used the Chun Yen

Testing Machines Co Ltd 100 Ton Micro Computer Universal Tensile Tester

Fig 31 Universal Testing Machine

42

Table 31 shows the specifications for this machine

Max Capacity 100 Ton

Accuracy plusmn1

Tension (mm) Max Space 1150mm

Grip for Rod 20-70mm

Ram Stroke 250mm

Effective Column Interval 940mm

Crosshead Speed 300mmmin

Testing Speed 0-50mmmin

Volume of Machine 1700times1000times3350mm(LtimesWtimesH)

Volume of Control Panel 1000times800times1500mm(LtimesWtimesH)

Weight 8000kg

Power 3∮220V 20A

Computer AMD K6-2-350

OS Windows XP

Screen 15rdquo CRT

Table 3-1 Chun Yen Testing Machine Specs Table

The connections diagram is shown in figure 3-2

Fig 3-2 Diagram for System Connections

43

When the test specimen is placed when the external force is applied the Load Cell can measure the

size of the applied force and the Encoder measures the expansion rate of change The Local Controller

receives all the information from the 2 units after arranging the results they are displayed in the

computer and they can be afterwards submitted for more complex analysis such as Finite Element

Analysis and we can get the Stress-Strain Diagram

322 Strain Measurement Equipment

The equipment used in our research provides a four-channel measurement that means we can use up

to 4 strain gauges at a time to do our measurements and provides 3 different bridge arrangements as

shown in figure 3-3

(a) (b) (c)

Fig 3-3 Input Connections for Strain Indicator

Figure 3-3 (a) is the Quarter Bridge (b) is the Half Bridge and (c) is the Full Bridge and Transducers

For our study we used the Quarter Bridge and use the Strain Gauge values to decide the position of the

connecting wires The Strain indicator is shown in figure 3-4

Fig 3-4 Vishay Micro-Measurements Model P3 Strain Indicator and Recorder

44

Input Connections Tool Free eccentric lever release

4-channel input

Wire diameter16-28AWG

Bridge Configurations Quarter- Half- and Full Bridge

Bridge Impedance 60-2000Ω

Display 128 64 pixel FSTN positive gray LCD

Data Conversion AD Converter filter

Measurement Range Resolution Strain Range plusmn155mVV

Resolution plusmn00005mVV

Measurement Accuracy plusmn01 of reading plusmn3 counts

Gage Factor Control 0500-9900

Balance Control Software either manual or automatic

Bridge Excitation 15VDC nominal

Communication Interface USB Cable Included

Data Storage Removable Media Card

Shunt Calibration Across bridge completion resistors controlled

by software When Gage Factor=200

120Ω350Ω1000Ω

Analog Output Value 0 to 25V max

Ranges plusmn320 microε plusmn3200 microε plusmn32000 microε

Error 05 output voltage +5mV

Max Error 14 output voltage + 20mV

Update rate 480 samplessec

Output Load 2000Ω

Power Battery Two Alkaline D cells

Battery life 400 hours typ

USB 5V 100mA

Operational Environment Temperature 0-50

Humidity Up to 90 Non-condensing

Case Aluminum Alloy

Size and Weight 228times152times152(mm) 20(kg)

Table 3-2 Vishay Micro-Measurements Model P3 Strain Indicator and Recorder Specs

45

323 Strain Gauge

The strain gaugersquos main basic principle is to use a resistancersquos characteristics to measure the strain

The inside connections of the strain indicator are shown in figure 3-5

Fig 3-5 Inner Connections

As shown above this is a quarter-bridge connection We connect equal-length 3 wires to the 2

connections allowed by the strain gauge wire 1 and 3 can be used to cancel out the effects of temperature

to the resistance and because of the addition of wires 1 and 3 wire 2 can directly measure the experiment

results from the strain gauge and therefore the strain developed with no influence of temperature

If there were no two measuring leads then the relations will be

R 4 =R g +2R L

Where Rg is the Strain Gauge Value and RL is the wire resistance then

4

4

R

R=

Lg

g

RR

R

2

=

gL

gg

RR

RR

21

amp

4

4

R

R=

g

g

R

R(1- L)

Where L is the Signal Loss Factor and so

L =gL

gL

RR

RR

21

2

g

L

R

2R if

g

L

R

2Rltlt1

46

(Actual Value R g =120R L =08g

L

R

2Ris always much smaller than 1)

R 4 =R g +2R LR 2 =R 3 =rR gR 1 =R g 32 RR =0

V 0 =V 2)1( r

r

(

4

4

R

R-

1

1

R

R)

The first term describes loss attenuation effects second term describes loss of balancing capabilities

effects

V 0 =V 2)1( r

r

[

)2

(Lg

g

RR

R

+

T

Lg

g

RR

R

)

2( + T

Lg

L

RR

R

)

2

2( -(

g

g

R

R) T ]

The first term describes loss attenuation effects and loss of balancing capabilities effects the second

third and fourth terms describe the temperature effects on the wire

For the three-wire method we have

L =gL

gL

RR

RR

1

g

L

R

R if

g

L

R

Rltlt1

V 0 =V 2)1( r

r

[

)(Lg

g

RR

R

+

T

Lg

g

RR

R

)( + T

Lg

L

RR

R

)

2( -

T

Lg

g

RR

R

)( - T

Lg

L

RR

R

)

2( ]

V 0 = V2)1( r

r

)(

Lg

g

RR

R

In the last four terms inside parenthesis we can see the effects of temperature being cancelled out and the

effect on first term is not great so this is the reason why in our research we use three wires

47

324 Specimen Measurements

The tensile specimens used in this research are compliant of ASTM E8 Tensile parameters as shown

in figure 3-6

Fig 3-6 Tensile Specimen

Diameter

D(mm)

Gauge

Length

G(mm)

Smallest

Arc

Radius

R(mm)

Shortest

Area

A(mm)

Total

Length

L(mm)

Clamping

Area

Length

B(mm)

Clamping

Area

Diameter

C(mm)

Bar 125 02 625 01 gt10 gt75 ~ 145 ~ 35 20

Table 3-3 Specifications for Round Bar

33 Experiment Procedure

1 Attaching the Strain Gauge to the Tensile Specimen

(1) Prepare 1 ASTM E8 compliant tensile specimen round bar as shown in figure 3-7

(2) Prepare Strain Gauge as those described in table 3-4

(3) Prepare other consumables and adhesive agent such as epoxy adhesive or

cyanoacrylate adhesive as shown in figure 3-8

48

Fig 3-7 Actual Tensile Specimen

Fig 3-8 Other Materials Used (Such as Alcohol gauze transparent tape adhesive)

Gage Type

EA-06-120LZ-120E

Resistance in ohms at 24∘C

1200plusmn03

Gage Factor at 24∘C

2075plusmn05

Transverse Sensitivity at 24∘C

(+07plusmn02)

Table 3-4 Specifications for Strain Gauge

2 Attaching Strain Gauge

As shown in following figures we shall explain the attachment of the strain gauge

(1) Use sand paper and a rasp to clean thoroughly the surface where the strain gauge will be

attached to

49

(a)

(2) Use alcohol to wash the surface where the strain gauge will be attached and use gauze to rub

it off

(b)

(3) Find a clean surface and clean it with alcohol and gauze

(c)

(4) Place the strain gauge in the clean surface Use a piece of transparent tape on top of the strain

gauge after securely placed rip it off the surface carefully

50

(d)

(5) Use a piece of white paper to mark the place where the strain gauge will be attached and in

this way we can make sure that the strain gauge will be placed as horizontally and vertically

correct as possible

(e)

(6) In the place where we had our mark place the strain gauge

(f)

(7) Carefully lift one side of the tape and apply some of the adhesive agent to both the strain

gauge and specimenrsquos surface

(g)

51

(8) We need to make sure that the gauge and the specimen will be firmly attached so we gently

apply pressure with our thumb

(h)

(9) After the adhesive is fully dry we can carefully rip off the tape

(i)

(10) We need to do the whole process twice one for the horizontally placed strain gauge and one

for the vertically placed strain gauge

52

(j)

(11) We now proceed to solder the wires to the strain gauge

(k)

(12) After soldering we use a Volt Multimeter to measure that there is no contact between wires

If there is none then the specimen is ready for testing

(l)

(13) We now need to measure a 5cm distance and mark it to check and compare the elongation

before and after the tensile testing

(m)

53

Fig 3-9 Specimen-Strain Gauge Process

3 Tensile Test

(1) Enter the computer application that controls the tensile testing machine

(2) Turn on the tensile testing machine main switch

(3) Adjust the hydraulic pump to go back to its original position

(4) Bring the lowering motor down to a distance enough so as to attach the tensile specimen to the

system open the clamps and secure the specimen

(a)

(5) Connect all the necessary wires to the strain indicator equipment

54

(b)

(6) Start the ascending motor and wait for the expansion

(c)

Fig 3-10 Specimen-Tensile Testing Process

4 Start the Test

(1) Enter the software application and enter some variables needed for the experiment in the

specific screen

(2) Go back to the main screen and press the [測試] (measure) button to start the test and auto

recording in the software

(3) After the specimen breaks the mechanical device will automatically stop and ask the user to

enter the total displacement We take out the specimen from the testing machine and adjust the

machinersquos position back to its original position

(4) Save the results information

(5) Record the results from the strain indicator

34 Results

From this experiment we can get the Poissonrsquos Ratio Youngrsquos Modulus and Yield Strength etc and

because of the slippage phenomenon in the clamp at the moment of the test then the Elastic Limit will

display some yield phenomena So omit any undesirable results we just take the Yield portion of the

results as reference

In the process of the experiment the most important part to attend to is the attaching of the strain

gauge because the gaugersquos purpose is to measure the strain developed during the test and this strain

might be very small If the gaugersquos angle change during the test ie is not well attached this will affect

the accuracy of the measurements of Poissonrsquos ratio and Youngrsquos modulus

55

The materials provided by the manufacturer are SUM 23 and SUM 43 steel round bars and these two

types of materials have been through different heat treatment processes so they can be sub-divided

further into untreated material heat-treated material and black surface heat treated material for the two

materials with heat treatment the treatment process and finished are different In the end we only have

the mechanical properties that were calculated after our research of these materials

All of the specifications are identical to those shown in figure 3-6

341 SUM 23

Fig 3-11 SUM 23 Untreated Material

Number 7 10

Hardness(HRB) 74 75

Yield Stress (MPa) 448 440

Tensile Strength (MPa) 544 560

Poissonrsquos Ratio 029 027

Youngrsquos Modulus (GPa) 203 210

Cut-off Area Shrinking () 42 41

Elongation () 1125 1011

Table 3-5 Mechanical Properties of SUM 23 Untreated

56

Stress-Strain Diagram

(a)

(b)

57

Fig 3-12 Stress-Strain Diagrams for (a) 7 Round Bar and (b) 10 Round Bar

Cut-Off Area

(a)

(b)

Fig 3-13 Cut-Off Area of (a) 7 Round Bar and (b) 10 Round Bar

58

SUM 23 Nickel Round Bar

Fig 3-14 SUM 23 Nickel Material

Number 1 2 3 4

Hardness(HRB) 48 50 49 48

Yield Stress (MPa) 370 370 380 400

Tensile Strength (MPa) 455 451 450 450

Poissonrsquos Ratio 028 046 029 026

Youngrsquos Modulus (GPa) 243 303 246 206

Cut-off Area Shrinking () 803 803 726 601

Elongation () 566 65 602 647

Table 3-6 Mechanical Properties of SUM 23 Nickel

59

Stress-Strain Diagram

(a)

60

(b)

(c)

(d)

61

Fig 3-15 Stress-Strain Diagrams for (a) 1 Round Bar (b) 2 Round Bar (c) 3 Round Bar and (d)

4 Round Bar

Cut-Off Area

(a)

(b)

62

(c)

(d)

Fig 3-16 Cut-Off Area of (a) 1 Round Bar (b) 2 Round Bar (c) 3 Round Bar and (d) 4 Round

Bar

63

SUM 23 Black Surface Round Bar

Fig 3-17 SUM 23 Black Surface Material

Number 1 2 3

Hardness(HRB) 51 50 51

Yield Stress (MPa) 378 371 369

Tensile Strength (MPa) 467 465 464

Poissonrsquos Ratio 03 016 04

Youngrsquos Modulus (GPa) 215 266 266

Cut-off Area Shrinking () 986 94 848

Elongation () 748 805 761

Table 3-7 Mechanical Properties of SUM 23 Black Surface Material

64

Stress-Strain Diagram

(a)

(b)

65

(c)

Fig 3-18 Stress-Strain Diagrams for (a) 1 Round Bar 2 Round Bar and (c) 3 Round Bar

Cut-Off Surface

(a)

66

(b)

(c)

Fig 3-19 Cut-Off Surface of (a) 1 Round Bar 2 Round Bar and (c) 3 Round Bar

67

342 SUM 43

Fig 3-20 Untreated SUM 43 Untreated Material

Number 1 5

Hardness(HRB) 76 75

Yield Stress (MPa) 572 594

Tensile Strength (MPa) 743 785

Poissonrsquos Ratio 027 029

Youngrsquos Modulus (GPa) 200 202

Cut-off Area Shrinking () 338 2944

Elongation () 857 894

Table 3-8 Mechanical Properties of SUM 43 Untreated

68

Stress-Strain Diagrams

(a)

(b)

Fig 3-21 Stress-Strain Diagrams for SUM 43 (a) 1 Round Bar and (b) 5 Round Bar

69

Cut-Off Area

(a)

(b)

Fig 3-22 Cut-Off Area of SUM 43 (a) 1 Round Bar and (b) 5 Round Bar

70

SUM 43 Nickel Round Bar

Fig 3-23 SUM 43 Nickel Material

Number 4 5

Hardness(HRB) 51 50

Yield Stress (MPa) 1580 1544

Tensile Strength (MPa) 1639 1625

Poissonrsquos Ratio 03 028

Youngrsquos Modulus (GPa) 194 201

Cut-off Area Shrinking () 1697 137

Elongation () 376 265

Table 3-9 Mechanical Properties of SUM 43 Nickel

71

Stress-Strain Diagrams

(a)

(b)

Fig 3-24 Stress-Strain Diagrams for (a) 4 Round Bar and (b) 5 Round Bar

72

Cut-Off Area

(a)

(b)

Fig 3-25 Cut-Off Area of (a) 4 Round Bar and (b) 5 Round Bar

73

SUM 43 Black Surface Material

Fig 3-26 SUM 43 Black Surface Material

Number 3 5

Hardness(HRB) 56 56

Yield Stress (MPa) 1416 1361

Tensile Strength (MPa) 1591 1402

Poissonrsquos Ratio 029 031

Youngrsquos Modulus (GPa) 200 202

Cut-off Area Shrinking () 139 124

Elongation () 24 24

Table 3-10 Mechanical Properties of SUM 43 Black Surface Material

74

Stress-Strain Diagrams

0 2 4 6 8 10 12 14

-200

0

200

400

600

800

1000

1200

1400

1600

1800

應力 (MPa)

應變()

(a)

0 2 4 6 8 10

-200

0

200

400

600

800

1000

1200

1400

1600

應力

(MPa)

位移 ()

(b)

Fig 3-27 Stress-Strain Diagrams for (a) 3 Round Bar and (b) 5 Round Bar

(Note These curves were formulated using Visual Solutions Inc VisSim Software)

75

Cut-Off Area

(a)

(b)

Fig 3-28 Cut-Off Area of (a) 3 Round Bar and (b) 5 Round Bar

76

The force value (N) was retrieved from the Universal Testing Machine

The Poissonrsquos Ratio (ε) is calculated as

ε =

the values for the Poissonrsquos Ratio are in average around 0297

The Youngrsquos Modulus (E) is calculated as

E =

Where

Stress =

Cross-sectional Area =

where D is the Diameter

The value for D was in average around 1258 mm

The values shown by the computer because there is Slippage phenomena between the Clamp and the

specimen will not be taken into consideration for the elongation strain and Youngrsquos modulus and we will

refer to the values that we have meticulously calculated

77

Chapter 4 AR COATING IN DEPTH

41 Experimentrsquos Purpose and Principles

By means of a vacuum chamber and several other instruments we intend to apply Anti-Reflective

Coating using deposition process to a laser diode and in this way reduce its refraction so as to make it

lose less light in the process of amplification and we can control certain wavelengths we want produced

for certain desired applications in our case we are attempting to re-create a Bose-Einstein Condensate

An optimal BEC apparatus is shown in figure 4-1

Fig 4-1 BEC Apparatus

The main point of this experiment is to build a vacuum chamber system attach all the instrumentation

needed (Vacuum pump deposition meter and voltmeter) and use it to apply AR coating to a laser diode

After we have accomplished the AR coating other team will be in charge of designing the BEC apparatus

and use the results of our research

78

42 Experimentrsquos Equipment

421 Vacuum Chamber

For this research we designed a vacuum chamber whose main body is shown in figure 4-2 Its

dimensions are

Width 240 mm

Length 240 mm

Height 200 mm

Outer Diameter 4 in

Inner Diameter 15 in

Fig 4-2 Vacuum Chamber Main Body

The chamber is made up of 6 pass ways pass way A is the connection with the Laser Deposition

Equipment pass way B is the connection with the Turbo Pump and pass way C is for the connection with

the Deposition Source

A

C

B

79

Pass way C is for the deposition source as mentioned above This is a system where a thermal

resistance is heated by passing a high current through it which heats up a filament boat (made of tungsten)

where the material to be evaporated is place We control the temperature as such that the material will

evaporate and the heat will not cause the filament boat to crack

Because P = Isup2 R (where P is power I is current and R is resistance) to avoid the current to flow

where it is not desired we decided that the material for the Thermocouple shown in figure 4-3 should be

Copper ᴓ 63 mm We choose it that way because Copper has very good heat dissipation characteristics

and the resistance value is low It can reduce the value of the current enough to make the thermocouple to

create heat

Fig 4-3 Thermocouple

To the thermocouple we attach the tungsten filament boat We need to take notice of materials to be

used in this design because when using high current the tungsten filament boar will heat up and so the

material must be able to keep up with the heating potential of tungsten and has a low coefficient of heat

dissipation to avoid the tungsten to fail when heating up and therefore not evaporating Considering all

this we decide to use Stainless Steel

Because this clamp will be assembled inside the chamber after many revisions it was determined it

will have the shape shown in figure 4-4

Fig 4-4 Filament Boat Clamp Design

80

For the tungsten filament boat we bought the product from a distributor The dimensions are

Length 100 mm

Width 10 mm

Height 1 mm

Our thermocouple is 15 in but the pass way C is 4 in so we need to attach a Flange that connects

15in to 4in Because these specifications are quite difficult to achieve by Milling we had to use

electrical wire cutting

For the laser clamping system where the laser that is going to be AR coated will be placed will be

connected to pass way A the assembly is shown in figure 4-5 below

Fig 4-5 Cover Assembly

For this design we used an O-ring instead of a gasket so as to save time The design of the assembly

where the laser will be placed is shown in figure 4-6

Fig 4-6 Upper Cover Inner Assembly

D

E

F

81

Point D is the plate in the assembly where the laser diode will be fixed Because of the easy

processing we decide to use Aluminum and it is screwed to the top cover Point E is the connection for

the Quartz crystal resonator and it is designed in the same as point F in this way the results of the quartz

microbalance system will be more accurate in real time Point F is the final resting place for the laser

diode We use a Thor Labs Base with dimensions of ᴓ 9mm and ᴓ 56mm for two different size laser

diodes It just needs to be plugged in for easy installation

From figure 4-6 we know that the system needs signal system connections and because of the

change in temperature inside the chamber this could affect the functioning of the quartz microbalance so

we also need to install water tubes for cooling This is shown in figure 4-7 below

Fig 4-7 Diagram of Upper Cover Connections

In figure 4-8 we show the Feed through connections and their functions

Fig 4-8 Feed through Diagram

82

1 SQM-160 wire 5 Laser Connection 1 (Vin)

2 SQM-160 (G) 6 Laser Connection 2 (G)

3 K-Type-1 7 Laser Connection 3 (PD)

4 K-Type-2 8 Not In Use

The fully assembled chamber is shown in figure 4-9

Fig 4-9 Fully Assembled Chamber

422 Quartz Crystal Microbalance

For measuring the deposition on our target for coating we used the Inficon SQM-160 RateThickness

Monitor It is an easy to use instrument for measuring many types of thin-film coatings as shown in

figure 4-10

(a) Front Panel (b) Back Panel

Fig 4-10 Inficon SQM-160

83

Table 4-1 shows the technical specifications for this equipment

Number of sensors 2 Standard 4 additional optional

Sensor Frequency Range 40 MHz ~ 60 MHz

Reference Frequency Accuracy 002

Thickness Display Resolution 1 Aring

Thickness Resolution 015 Aring (Std) 0037 Aring (Hi Res)

Density of Stored Films 05-9999 gmcc

Tooling 10-399

Z-Factor 010-1000

Final Thickness 0000-9999k Aring

Measurement Period 15 to 2 sec

Simulation Mode Yes

Frequency Mode Yes

Rate Resolution 011 Arings

Dual Crystal Yes

Etch Mode Yes

Crystal Tooling 10-399

Crystal Fail Min Max 40 to 60 MHz 41 to 61 MHz

Power 100-120 200-240~plusmn10 nominal 20W

Operation Environment 0degC ~ 50degC

0 ~ 80 RH non-condensing

0 ~ 2000 meters

Class 1 Equipment

Pollution Degree 2

Rack Dimensions 885mm x 2127mm x 1969mm

Weight 27 kg

Table 4-1 Inficon SQM-160 RateThickness Monitor Specs

84

To the SQM-160 we need to connect an Oscillator We use the Sigma Instruments Remote Oscillator

Ser No 2 268 as shown in figure 4-11

Fig 4-11 Sigma Instruments Remote Oscillator

The connections diagram is shown in figure 4-12

Fig 4-12 SQM-160 Connections Diagram

85

423 Turbo Pump

For our experiments we used the Pfeiffer TCP 015 Electronic Drive Unit shown below in figure 4-13

Table 4-2 shows the technical specifications for this equipment

(a) Front Panel (b) Back Panel

Fig 4-13 Pfeiffer TCP 015 Electronic Drive

Connection Voltage (100V) 90-112

Mains Frequency 5060 Hz

Start-up Current 22 A

Nominal Frequency 1500 Hz

Rotation Speed 10V = 1500Hz plusmn2

Analog Output Current 10 V = 25 A plusmn 5

Rotation Speed Switchpoint 750 Hz

Works Setting 8 min

Permissible Ambient Temperature 0degC ~ 40degC

Dimensions Front Panel 1285mm x 1063mm

Insertion Length 227mm

Weight 27 Kg

Table 4-2 Pfeiffer TCP 015 Electronic Drive Specs

86

The connections diagram is shown in figure 4-14

Fig 4-14Connections Diagram for Pfeiffer TCP 015

To measure the pressure inside the chamber we use the Granville Phillips 375 Convectron Vacuum

Pressure Controller shown in figure 4-15

(a) Front Panel (b) Back Panel

Fig 4-15 Granville Phillips 375 Convectron

87

Its dimensions are shown in figure 4-16

Fig 4-16 Dimensions of Convectron

Table 4-3 shows the technical specifications for this equipment

Table 4-3 Granville Phillips 375 Convectron Vacuum Pressure Controller Specs

88

424 Multimeter

For our experiment we used the Keithley 2000 Digital Multimeter as shown in figure 4-17

(a) Front Panel (b) Back Panel

Fig 4-17 Keithley Model 2000 6-12-Digit Digital Multimeter

Its technical specifications are shown in table 4-4

Table 4-4 Keithley Model 2000 6-12-Digit Digital Multimeter Specs

89

43 Experiment Procedure

1 Connecting together the equipment and the chamber

(1) We first connect the resonator to the thickness monitor and connect the other side to the

chamber

(2) We now connect the flexible tubes to the turbo pump on one side and to the chamber on the

other

(3) We need to check that tubes are tightly connected to avoid any leaks in the vacuum pumping

process which will not allow us to get to our goal of Torr As shown in figure 4-18

(4) Connect the convectron to the system as shown in figure 4-19

Fig 4-18 checking for leaks using alcohol

Fig 4-19 Convectron attached to System

90

(5) Attach the clamps of the Multimeter to the bottom of the chamber as shown in figure 4-20

(6) Place the Quartz crystal in place

(7) Close tight vacuum chamber

(8) Connect all electrical appliances to power source

Fig 4-20 Multimeter Connections

2 Starting up the System

(1) We turn on all the devices as such Check all systems are ready to function Reset all values

that might be left over from previous tests

(2) Start the thickness monitor and set all values for this experiment In our case we got to testing

the system but not actual coating So we used the simulation mode of the thickness monitor as

shown in figure 4-21

Fig 4-21 Simulation Mode

91

(3) Start the turbo pump Make sure the lid on the vacuum chamber is tightly closed

(4) Start convectron and record initial pressure

(5) Start Multimeter and record initial current

3 Coating Process

(1) If we have the deposition material inside the filament boat the power source for the high

current must be started as well

(2) Record all initial values for thickness current pressure

(3) For an ideal experiment we need a thickness of around 101 nm a pressure of Torr and

a current of 300 A

44 Results

From previous experiments we have shown that we can turn a LED into a laser by means of AR

Coating In figure 4-22 shown below we can compare the actual results of a Diode before and after AR

coating From the blue line we can see that when the diode is at a current of 15mA its light will change

from LED to laser and if we look at the red line its critical current is around 30 to 35 mA

Fig 4-22 AR Coating Comparison for Laser Diodes

This means that the light emitted is not as strong as if the diode had been coated because inside the

chamber there must be some excitation first so the reflectivity of both sides inside the diode must be high

So because of the coating in one of the sides we have opened a door and let the light come out so the

critical current is risen as such and will be higher value than that of before the coating

92

In the following figures we can see the difference between before and after coating in a material The

thickness is around 1016 nm for this material

Fig 4-23 Before Coating

Fig 4-24 After Coating

93

Chapter 5 CONCLUSIONS AND RECOMMENDATIONS

51 Conclusions

For the first part of this independent study taking into consideration the data that came out of our

research and that sent by the provider we can say

1 SUM 23 after heat treatment will unexpectedly develop cracking in the middle of the tensile

testing process and suddenly break

2 Itrsquos possible that in the process of heat treatment to the SUM 23 material the treatment was not

uniform and this will create a pre-loaded moment force on one side that pushes on the other side

of the specimen resulting in material deformation

3 In the process of attaching the strain gauges to the materials it is very easy to make errors due to

poor adhesion or sudden removal in the tensile testing process

For our second part of the independent study the following can be made

1 At the beginning of this independent study we had no idea what Bose-Einstein Condensate was

or what was its purpose After much literature we finally comprehended the basic principles to

put into practice for our research

2 Our systemrsquos basic working principles and equipmentrsquos complexity are a little difficult to grasp

but hopefully we were able to understand enough of it

3 Theoretically from relation between the power and current we can know the advantages and

disadvantages of AR Coating

4 We were able to assemble the system and run test on its functions Even though we were able to

do this there is still much more work left to do with this system

52 Recommendations

For the Tensile Testing the following can be said

1 Ask the provider to check on the process of heat treatment on the SUM 23 material and give

them the information we have gathered through our test so they can correct for the mechanical

properties found if any change is needed

2 To avoid the problem of the inaccuracy of the poor adhesion of strain gauges we can attach

multiple strain gauges to the same one specimen so as to correlate data and improve our results

For the AR Coating the following can be said

1 We need to make sure that there are no physical defects on the main body of the chamber so as to

achieve maximum efficiency in the vacuum process If there was then the vacuum will arrive to

certain point and then start to decrease

2 It would be preferable to add some sort of visual aid that will allow the user to check the inside of

the chamber without actually opening it This will help us determine at what times we should

manipulate the current to better evaporate the substrate

94

REFERENCES

[1] A L Window Strain Gauge Technology Elsevier Applied Science London and New York 2nd

Edition 1992

[2] CC Perry and HR Lissner Strain Gauge Primer McGraw-Hill Book Co Inc New York 1955

[3] James W Dally William F Riley McGraw-Hill 1978

[4] University of Colorado Boulder BEC - What is it and where did the idea come from

httpwwwcoloradoeduphysics2000becwhat_is_ithtml

[5] Ultraslow Light amp Bose-Einstein Condensates Two-way Control with Coherent Light amp Atom

Fields Harvard Hau Lab Dr Lene Vestergaard Hau Optics amp Photonics News 16 1995

[6] The Art of Taming Light Ultra-slow and Stopped Light Harvard Hau Lab Dr Lene

Vestergaard Hau Europhysics News 2004

[7] Nonlinear Optics Shocking Superfluids Harvard Hau Lab Dr Lene Vestergaard Hau Nature

Physics 2007

[8] Model P3 Strain Indicator and Recorder Instruction Manual Vishay Micro-Measurements 2005

[9] Granville-Phillips Series 375 Convectron Vacuum Gauge Controller Instruction Manual Brooks

Automation 2008

[10] Effect of Film Thickness on the Validity of the Sauerbrey Equation for Hydrated Polyelectrolyte

Films Vogt Lin Wu White 2004

[11] Quartz Crystal Microbalance Study of DNA Immobilization and Hybridization for DNA Sensor

Development Chang Zhao 2008

[12] Installation of Strain Gages with SR-4 PrecoatAdhesive Vishay Micro-Measurements 2005

[13] Strain Gauge Measurement ndash A Tutorial National Instruments 1998

[14] Correlation between Vickers Hardness Number and Yield Stress of Cold-Formed Products

Yavuz Tekkaya

[15] httpsenwikipediaorg

Page 2: PC Hinge Materials Testing and AR Laser Diode Coating

2

ABSTRACT

Project Name PC Hinge Materials Testing and AR Laser Diode Coating

School National Taipei University of Technology Mechanical Engineering Department

Graduation Time June 2012 Degree Bachelor in Science

Student Name Jorge Sanchez Advisor Prof Ho-Chiao Chuang

Keywords Hinge Youngrsquos modulus Poisson ratio material properties Boson

Bose-Einstein Condensate Reflectivity

The focus of this independent study research is divided into two The first was done in

National Taipei University of Technology Mechanical Engineering Department under the

guidance of Prof Ho-Chiao Chuang while the second was done in joint research with Institute

of Atomic and Molecular Sciences Academia Sinica from Taiwan under the guidance of Prof

Ho-Chiao Chuang and Dr Ming-Shien Chang PhD

In response that new generation computers are gradually reducing their size the diameter of

the structures of the hinges used by NB computers must also follow but the hinge strength may

also become smaller due to the reduction of diameter and result in the phenomenon of

insufficient strength In addition the disk-type spring that is source of the torque may also be

insufficient due to the narrowing of the structure Therefore it is necessary to direct a structural

analysis of the hinge for the existing laptops so that we can identify the stress concentration

point The stress concentration point is usually the point where material damage behavior is

encountered the easiest and if we can find the point where breaking occurs most often we can

improve the design of the existing structure to enhance the strength of the hinge structure

Second the structure of the hinge is too complicated the traditional mechanics of materials

analysis methods and formulas are no longer suitable for analysis of a wide arrange of hinge

design In recent years finite element analysis methods have been widely applied in various

fields such as electronics machinery aviation and so on

Therefore one of this independent study projectrsquos focus is to test hinge materials

acquired from cooperate manufacturers by means of tensile testing and then obtain the materials

3

special properties such as Youngrsquos modulus Poisson ratio yield strength tensile strength and

so on The experimental results may be entered into the subsequent finite element analysis

software the objective is to enter the materialrsquos real parameters to make the structural analysis

simulation more realistic

The 2nd

focus of this independent study is to help in the further research of the

Bose-Einstein condensate This is a state of matter of a dilute gas weakly interacting bosons

(subatomic particles that obey the Bose-Einstein statistics) confined in an external potential and

cooled down to temperatures very near absolute zero (0 K or -27315deg C) Under these conditions

a large number of bosons occupy the lowest quantum state of the external potential at which

point quantum effects become apparent at macroscopic scale This state of matter was predicted

by Satyendra Nath Bose and Albert Einstein in 1924~1925 Then 70 years later the 1st gaseous

condensate was produced by Eric Cornell and Carl Wieman in 1995 at the University of

Colorado (Boulder) NIST-JILA lab and because of this along with Wolfgang Ketterle of MIT

they received the 2001 Nobel Prize in Physics

We designed and have constructed a vacuum chamber where Anti Reflecting Coating will be

applied to laser diodes in order to reduce the reflectivity of the laser diodersquos surface to make

effective the injection lock This creates a desired wavelength of light inside a laserrsquos pumping

medium and may reduce surface reflection coefficient to less than 01 We expect to obtain

certain desired working properties after this process which will allow us to continue our project

We hope that through our research we can find significant applications to this theory

4

ACKNOWLEDGEMENT

First and foremost I would like to thank God I would never have done this study without the

faith I have in you the Almighty

I would like to thank my parents Gloria Iveth Sanchez and Juan Carlos Bonilla my sisters

Joanna Iveth Bonilla Karla Ines Bonilla and Kelly Gabriela Bonilla and my entire family for

their love support patience and understanding during my 5 years of studying abroad

I owe my deepest gratitude to my advisor Professor Ho-Chiao Chuang PhD for letting me

carry out this study Without his support and comprehension this study would have never been

carried out

Special thanks to Institute of Atomic and Molecular Sciences Academia Sinica Dr

Ming-Shien Chang for without him I would not be able to understand and put into practice

some of the principles presented in this thesis

I am indebted to many friends and classmates for the invaluable support during my studies in

this country and in this University

A special mention to my beloved friends Christian Reyes Francisco Garcia Jose Pagoada

and Olvin Castillo to my classmates 姚呈忠 王煜璨 林炯宇 for helping me during my tough

times my senior 廖梃君 and my junior 石中鈺 for thanks to them I was able to work and

present results during the course of this research and everyone else involved at the Department

of Mechanical Engineering at National Taipei University of Technology

5

TABLE OF CONTENTS

ABSTRACThelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 2

ACKNOWLEDGEMENThelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 4

TABLE OF CONTENTShelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 5

LIST OF TABLEShelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 7

LIST OF FIGUREShelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 8

CHAPTER 1 Introductionhelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 10

11 Motivation and Backgroundhelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 10

12 Research Objectivehelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 11

13 Methodologyhelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 13

14 Organization of the Thesishelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 13

CHAPTER 2 Basic Principleshelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 14

21 Tensile Testinghelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 14

211 Youngrsquos Modulushelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 14

212 Yield Strength and Yield Pointhelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 15

213 Ultimate Tensile Strength and Breaking Strengthhelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 16

214 Poissonrsquos Ratiohelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 16

215 Strain Gauge Basic Principleshelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 16

22 Hardness Test Basic Principleshelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 18

221 Brinell Scale BHNhelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 18

222 Rockwell Scale HRhelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 19

223Vickers Hardness Test HVhelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 21

23 AR Coatinghelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 22

231 Bose-Einstein Condensatehelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 22

232 AR Coating Basic Principleshelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 25

233 Laser Diode Basic Principleshelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 28

234 Quartz Microbalance Systemhelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 29

235 Vacuum Chamber Systemhelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 38

CHAPTER 3 Tensile Testing in depthhelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 41

31 Experimentrsquos Purpose and Principleshelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 41

32 Experimentrsquos Equipmenthelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 41

321 Universal Testing Machinehelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 41

322 Strain Measurement Equipmenthelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 43

6

323 Strain Gaugehelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 45

324 Specimen Measurementshelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 47

33 Experiment Procedurehelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 47

34 Resultshelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 54

341 SUM 23helliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 55

342 SUM 43helliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 67

CHAPTER 4 AR Coating in depthhelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 77

41 Experimentrsquos Purpose and Principleshelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 77

42 Experimentrsquos Equipmenthelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 78

421 Vacuum Chamberhelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 78

422 Quartz Microbalancehelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 82

423 Turbo Pumphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 85

423 Multimeterhelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 88

43 Experiment Procedurehelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 89

44 Resultshelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 91

CHAPTER 5 Conclusions and Recommendationshelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 93

51 Conclusionshelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 93

52 Recommendationshelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 93

REFERENCEShelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 94

7

LIST OF TABLES

Table 2-1 Rockwell Hardness Test Scalehelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 20

Table 2-2 Z-Ratios for Different Materialshelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 33

Table 2-3 Classifications of Vacuumhelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 39

Table 3-1 Chun Yen Testing Machine Specshelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 42

Table 3-2 Vishay Micro-Measurements Model P3 Strain Indicator and Recorder Specshelliphelliphelliphelliphelliphellip 44

Table 3-3 Specifications for Round Barhelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 47

Table 3-4 Specifications for Strain Gaugehelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 48

Table 3-5 Mechanical Properties of SUM 23 Untreatedhelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 55

Table 3-6 Mechanical Properties of SUM 23 Nickelhelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 58

Table 3-7 Mechanical Properties of SUM23 Black Surface Materialhelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 63

Table 3-8 Mechanical Properties of SUM 43 Untreatedhelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 67

Table 3-9 Mechanical Properties of SUM 43 Nickelhelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 70

Table 3-10 Mechanical Properties of SUM 43 Black Surface Materialhelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 73

Table 4-1 Inficon SQM-160 RateThickness Monitor Specshelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 83

Table 4-2 Pfeiffer TCP 015 Electronic Drive Specshelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 85

Table 4-3 Granville Phillips 375 Convectron Vacuum Pressure Controller Specshelliphelliphelliphelliphelliphelliphelliphelliphellip 87

Table 4-4 Keithley Model 2000 6-12-Digit Digital Multimeter Specshelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 88

8

LIST OF FIGURES

Fig 1-1 Notebook Computer Hingehelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 11

Fig 1-2 Basic Structure of Laserhelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 11

Fig 1-3 Comparison between LED and Laser Diodehelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 12

Fig 1-4 External Cavity Designhelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 12

Fig 2-1 Stress-Strain Curvehelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 14

Fig 2-2 Stress-Strain Curve Comparison on Metalshelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 15

Fig 2-3 Basic Structure of Strain Gaugehelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 17

Fig 2-4 Strain Gauge Attached to Wheatstone Bridgehelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 18

Fig 2-5 Brinell Indentationhelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 18

Fig 2-6 Brinell Hardness Testerhelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 18

Fig 2-7 Rockwell Indentationhelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 19

Fig 2-8 Rockwell Hardness Testerhelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 19

Fig 2-9 Vickers Indentationhelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 22

Fig 2-10 Vickers Hardness Testerhelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 22

Fig 2-11 Bose-Einstein Condensate at different scaleshelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 23

Fig 2-12 Super Conductorhelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 24

Fig 2-13 Simple Model for Light in Glass Mediumhelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 25

Fig 2-14 Simple Model for Light in Glass Medium after AR Coatinghelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 26

Fig 2-15 Light Passing through AR Coating and Glasshelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 27

Fig 2-16 Lens without and with AR Coatinghelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 27

Fig 2-17 Laser Diodehelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 28

Fig 2-18 Tunable Laser Basic Configurationhelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 28

Fig 2-19 Light Spectrumhelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 29

Fig 2-20 Front and Back Panel of SQM-160helliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 29

Fig 2-21 QCM Crystalshelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 31

Fig 2-22 SQM-160 Oscillatorhelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 31

Fig 2-23 Oscillator Circuithelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 32

Fig 2-24 Vacuum Evaporation Systemhelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 39

Fig 2-25 Turbo Pumphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 39

Fig 2-26 Control and Measurement Equipmenthelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 40

Fig 2-27 Complete Systemhelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 40

Fig 3-1 Universal Testing Machinehelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 41

Fig 3-2 Diagram for System Connectionshelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 42

Fig 3-3 Input Connections for Strain Gaugehelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 43

Fig 3-4 Vishay Micro-Measurements Model P3 Strain Indicator and Recorderhelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 43

Fig 3-5 Inner Connectionshelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 45

Fig 3-6 Tensile Specimenhelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 47

Fig 3-7 Actual Tensile Specimenhelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip47

Fig 3-8 Other Materials Usedhelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 48

Fig 3-9 Specimen-Strain Gauge Processhelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 49

Fig 3-10 Specimen-Tensile Testing Processhelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 53

9

Fig 3-11 SUM 23 Untreated Materialhelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 55

Fig 3-12 Stress-Strain Diagrams for 7 and 10 Round Barhelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 56

Fig 3-13 Cut-Off Area of 7 and 10 Round Barhelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 57

Fig 3-14 SUM 23 Nickel Materialhelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 58

Fig 3-15 Stress-Strain Diagrams for 1 2 3 and 4 Round Barhelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip60

Fig 3-16 Cut-Off Area of 1 2 3 and 4 Round Barhelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 62

Fig 3-17 SUM 23 Black Surface Materialhelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 63

Fig 3-18 Stress-Strain Diagrams for 1 2 and 3 Round Barhelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 65

Fig 3-19 Cut-Off Area of 1 2 and 3 Round Barhelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 66

Fig 3-20 SUM 43 Untreated Materialhelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip67

Fig 3-21 Stress-Strain Diagrams for 1 and 5 Round Barhelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 68

Fig 3-22 Cut-Off Area of 1 and 5 Round Barhelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 69

Fig 3-23 SUM 43 Nickel Materialhelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 70

Fig 3-24 Stress-Strain Diagrams for 4 and 5 Round Barhelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 71

Fig 3-25 Cut-Off Area of 4 and 5 Round Barhelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 72

Fig 3-26 SUM 43 Black Surface Materialhelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 73

Fig 3-27 Stress-Strain Diagrams for 3 and 5 Round Barhelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 74

Fig 3-28 Cut-Off Area of 3 and 5 Round Barhelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 75

Fig 4-1 BEC Apparatushelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 77

Fig 4-2 Vacuum Chamber Main Bodyhelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 78

Fig 4-3 Thermocouplehelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip79

Fig 4-4 Filament Boat Clamp Designhelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 79

Fig 4-5 Cover Assemblyhelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 80

Fig 4-6 Upper Cover Inner Assemblyhelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 80

Fig 4-7 Diagram of Upper Cover Connectionshelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 81

Fig 4-8 Feed Through Diagramhelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 81

Fig 4-9 Fully Assembled Chamberhelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 82

Fig 4-10 Inficon SQM-160helliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 82

Fig 4-11 Sigma Instruments Remote Oscillatorhelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 84

Fig 4-12 SQM-160 Connections Diagramhelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 84

Fig 4-13 Pfeiffer TCP 015 Electronic Drivehelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 85

Fig 4-14 Connections Diagram for Pfeiffer TCP 015helliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 86

Fig 4-15 Granville Phillips 375 Convectronhelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 86

Fig 4-16 Dimensions of Convectronhelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 87

Fig 4-17 Keithley Model 2000 6-12-Digit Digital Multimeterhelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 88

Fig 4-18 Checking for Leaks Using Alcoholhelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 89

Fig 4-19 Convectron Attached to Systemhelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 89

Fig 4-20 Multimeter Connectionshelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 90

Fig 4-21 Simulation Modehelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 90

Fig 4-22 AR Coating Comparison for Laser Diodeshelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 91

Fig 4-23 Before AR Coatinghelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 92

Fig 4-24 After AR Coatinghelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 92

10

Chapter 1 INTRODUCTION

11 Motivation and Background

In response that new generation computers are gradually reducing their size the diameter of

the structures of the hinges used by NB computers must also follow but the hinge strength may

also become smaller due to the reduction of diameter and result in the phenomenon of

insufficient strength In addition the disk-type spring that is source of the torque may also be

insufficient due to the narrowing of the structure Therefore it is necessary to direct a structural

analysis of the hinge for the existing laptops so that we can identify the stress concentration

point The stress concentration point is usually the point where material damage behavior is

encountered the easiest and if we can find the point where breaking occurs most often we can

improve the design of the existing structure to enhance the strength of the hinge structure

Second the structure of the hinge is too complicated the traditional mechanics of materials

analysis methods and formulas are no longer suitable for analysis of a wide arrange of hinge

design In recent years finite element analysis methods have been widely applied in various

fields such as electronics machinery aviation and so on

Therefore to meet the need of the industry and with the purpose of reducing design time

how to design a notebook computer hinge without compromising mechanical stability and

materialrsquos hardness which will operate equally under equal conditions In other words be able to

meet the needs of the size decreasing NB computers market as the needs for this kind of

accessories will increase in the near future If we take into consideration the traditional ways of

design we seek to reduce the costs of use of machinery and molding by applying Finite Element

Analysis methods to our study and also increase the flexibility of designing methods

The second project was brought in by Prof Chuang and it is to help in the further research of

the Bose-Einstein condensate This is a state of matter of a dilute gas weakly interacting bosons

(subatomic particles that obey the Bose-Einstein statistics) confined in an external potential and

cooled down to temperatures very near absolute zero (0 K or -27315deg C) Under these conditions

a large number of bosons occupy the lowest quantum state of the external potential at which

point quantum effects become apparent at macroscopic scale This state of matter was predicted

by Satyendra Nath Bose and Albert Einstein in 1924~1925 Then 70 years later the 1st gaseous

condensate was produced by Eric Cornell and Carl Wieman in 1995 at the University of

Colorado (Boulder) NIST-JILA lab and because of this along with Wolfgang Ketterle of MIT

they received the 2001 Nobel Prize in Physics

11

We wish to investigate the properties of Anti Reflecting Coating on laser diodes Hopefully

we will be able to achieve the desired effect of reducing the surface reflection coefficient and

find applications for it

12 Research Objective

We wish to analyze the normal composition of the notebook computerrsquos hinge at which

point in the assembly is clearly the weakest and at this time in the assembly the strength and

durability are influenced The main point is to see if we can affect the normal operation and work

life

The objective of this thesis is to present the results of the material properties under tensile

testing find the mechanical properties and after using finite element analysis determine what

material is the best for our purposes

Fig 1-1 Notebook Computer Hinge

For our second research we wish to produce and analyze laser diodes with anti-reflective

coating and test its properties and applications

When semi-conductor laser has been submitted to current it will produce resonance inside it

and light will be stimulated to come out Please refer to figure 1-2 for the basic structure of a

laser

Fig 1-2 Basic Structure of a Laser

1 Gain Medium

2 Laser Pumping Energy

3 High Reflector

4 Output Coupler

5 Laser Beam

12

But when the laser diode generates light but the laser diode canrsquot produce light on itself it

must wait for the current to be higher than certain value which is called the critical current Until

the light goes over this threshold then it is considered laser light if not it is just considered as a

common LED light source Please refer to figure 1-3

Fig 1-3 Comparison between LED and Laser Diode

As we can see from figure 1-3 all of the light that goes over the critical current is laser light

and so the external cavity semi-conductor laser that we built needs Anti-Reflective Coating

because the method we want to use needs an external cavity laser that has been covered with AR

Coating and a Diffraction Grating We use this configuration first by shooting the laser to the

grating and this will be shot back to the laser creating the external resonance cavity which is

shown in figure 1-4

Fig 1-4 External Cavity Design

13

Two configurations are shown the Littrow Configuration and the Littman-Metcalf

Configuration The Littrow configuration contains a collimating lens and a diffraction grating as

the end mirror The first order diffracted beam provides optical feedback to the laser diode which

has AR Coating The emission wavelength can be turned by rotating the diffraction grating A

disadvantage is that it also changes the direction of the output beam

In the Littman-Metcalf configuration the grating orientation is fixed and an additional mirror

is used to reflect the first order beam back to the laser diode The wavelength can be turned by

rotating that mirror This configuration offers a fixed direction of the output beam and also tends

to exhibit smaller line width as the wavelength selectivity is stronger A disadvantage is that

zero order reflection of the beam reflected by the tuning mirror is lost so that the output power is

less than that of a Littrow laser

13 Methodology

The aim of this research is to find the mechanical properties of materials after being

subjected to tensile testing through finite element analysis observations and determine what

material is best for our purposes taking into consideration the strength and durability of the

material among other properties to find use and applications for the AR coated laser diodes to

further improve the grasp of the Bose-Einstein condensation working principles

14 Organization of the Thesis

The research paper includes five chapters

1 Chapter 1 explains the motivation background objective and methodology of this study

2 Chapter 2 explains the working principles and basic knowledge needed to understand this

study

3 Chapter 3 explains the tensile testing in detail steps methods and results

4 Chapter 4 explains the AR coating in detail steps methods and results

5 Chapter 5 is the conclusions taken from the results shown in chapter 3 and 4 and

recommendations done after arranging and critical thinking

14

Chapter 2 BASICS THEORIES

21 Tensile Testing

After a specimen is tested with the use of tensile testing we can get the Stress-Strain Curve using the

relation between tension and displacement Typical curves are shown in Fig 2-1

(a) Ductile materials (b) Brittle materials

Fig 2-1 Stress-Strain Curve

The curve is unique for each material and is found by recording the amount of deformation at distinct

intervals of tensile or compressive loads Thanks to the use of the Stress-Strain curve we can get very

useful information such as

211 Youngrsquos Modulus (E)

As shown in Fig 2-1 as long as the external load is not greater than the Proportional Limit the Stress

(σ) and Strain (ε) remain as a linear relation fulfilling Hookersquos Law

σ = Eε

The slope is the constant factor the inverse of the modulus of elasticity E also called Youngrsquos

modulus When the external load goes over the proportional limit the stress-strain relationship doesnrsquot

follow the linear relation anymore but the deformation remains flexible When the load is released the

deformation is completely eliminated and the specimen goes back to its original state This is called

15

Elastic Deformation When the external load goes over the Elastic limit only then does the specimen

presents Plastic Deformation This type of deformation which is irreversible even when the load is

removed comes after the material does under elastic deformation so this means the object will first come

part way to its original shape Common metals and ceramics have roughly the same elastic limits

212 Yield Strength and Yield Point

Some materials display very evident yield phenomena while some materials donrsquot as shown in Fig

2-2 After we exceed the elastic limit if we continue to exert load when we arrive to a certain value

which differs under different materials and external conditions there is sudden decrease in stress and this

is called the Yield Strength and can be defined as the stress at which a material begins to deform

plastically using the equation

σyield =

Where P is the tension force and Ao is the original cut-off area

The stress remain at a certain value after the decrease but the strain increases this phenomena can be

easily appreciated when studying the behavior of common Carbon Steel Fig2-2 (a) but most metals (like

Aluminum Copper or High Steel Carbon) donrsquot display this kind of behavior as shown in Fig 2-2 (b)

Arriving to this point is very difficult and the most commonly used method for this is to add a 02 or

0002 offset yield strength to the curve This point is held constant on the strain axis of the curve and

from the 0002 position we draw a straight line parallel to the linear relationship line the point at where

this line and the stress-strain curve intercept is the point we take as the 02 offset yield strength

(a)Evident (b) Non-evident

Fig2-2 Stress-Strain Curve Comparison on Metals

16

213 Ultimate Tensile Strength and Breaking Strength

After materials undergo yield they keep lending strength and hardening phenomena occurs (work

hardening) on the material and the external load increases When it has reached the highest point this is

called the Ultimate Tensile Strength (UTS) as shown in Fig2-1 The UTS is defined as

σUTS =

Where Pmax is the load at the materialrsquos ultimate tensile strength point and Ao is the original cut-off

area For brittle materials the ultimate tensile strength is the most important mechanical property for

ductile materials the ultimate tensile strength is not commonly used for industrial and designing purposes

because upon arriving to this value the material already has forgone great plastic deformation After the

specimen goes through UTS there will be necking phenomena which is a mode of tensile deformation

where relatively large amounts of strain localize disproportionately in a small region of the material It

results from instability during tensile deformation when a materialrsquos cross-sectional area decreases by a

greater proportion than the material strain hardens The specimen continues to elongate until it finally

breaks and the load at this point is called Breaking Strength The breaking strength is defined as the

greatest stress in tension that a material is capable of withstanding without rupture

Where Pf is the load at the materialrsquos breaking strength point and Ao is the original cut-off area

214 Poissonrsquos Ratio (ν)

For elastic deformation when materials are compressed in one direction they tend to expand in the

other two directions perpendicular to the direction of compression This is called the Poissonrsquos Effect

The Poison Ratio is a measure of the Poissonrsquos effect It is the ratio of the fraction of expansion divided

by the fraction of compression for small values of these changes

ν=-

215 Strain Gauge Basic Principles

The strain gauge is a device used to measure the strain of an object Itrsquos an elongated metal resistor

which is attached to the specimen being measured and when the specimen is under strain and starts to

deform the strain gauge will have a change in the resistance With the change in value we can calculate

the elementrsquos strain or elastic modulus and the Poissonrsquos ratio

It takes advantage of the physical property of electrical conductance and its dependence on the

conductorrsquos geometry When the electrical conductor (the specimen being tested) is stretched within the

limits of elasticity such that it does not break or deform plastically it will become narrower and longer

17

which increases the electrical resistance through-out From the measured resistance of the strain gauge

the amount of stress may be inferred by using the relations

R=

Where R is the original resistance value is the electrical resistivity lo is the original length of the

conductor and Ao is the original cross sectional area of the conductor If after the application of tension

the change in length is Δl let the length of the specimen be l = l + Δlo and the tension is the same

through-out So

And the resistance is

The Gauge Factor is the ratio of relative change in electrical resistance to the mechanical strain in

other words it is the relative change in length It is defined as

The strain gauge was invented in 1938 by Edward E Simmons and Arthur C Ruge and the most

common type consists of an insulating flexible backing which supports a metallic foil usually made of a

brass-nickel alloy It is attached to the specimen by a suitable adhesive As the object is deformed the foil

also deforms and this causes the electrical resistance to change Then this is usually measured using a

Wheatstone bridge shown below and is related to the strain by the Gauge Factor

Fig2-3 Basic Structure of Strain Gauge

18

Fig 2-4 Strain gauge attached to Wheatstone bridge

22 Hardness Testing Basic Principles

221 Brinell Scale BHN

The Brinell Scale characterizes the indentation hardness of materials through the scale of penetration

of an indenter loaded on a material specimen The typical test uses a 10mm diameter steel ball as indenter

(usually of value equal to BHN450) with a 29kN force For softer materials smaller force is used The

indentation is measured and BHN is calculated using the relation

BHN =

radic

Where F is the applied force usually within the range of 100 250 500 750 1000 1500 2000 2500

and 3000 kgf D is the diameter of indenter usually within the range of 5mm or 10mm plusmn0005 margin

and d is the diameter of indentation usually around 2mm Its units are of Kgmmsup2 but are not normally

written

First proposed by Swedish engineer Johan August Brinell in 1900 it was the first widely used and

standardized hardness test in engineering and metallurgy although the large size of indentation and

possible damage to specimen limits its usefulness

Fig 2-5 Brinell Indentation Fig2-6 Brinell Hardness Tester

19

222 Rockwell Scale HR

The Rockwell scale is a hardness scale based on the indentation hardness of a material The Rockwell

test determines the hardness by measuring the depth of penetration of an indenter under a large load

compared to the penetration made by a preload The indenter is forced into the specimen under a

preliminary load When equilibrium is reached a measuring device follows the movements of the

indenter and responds to changes in depth of penetration of the indenter While the preload is still being

applied additional major load is applied resulting in increased penetration When equilibrium is reached

again the major load is removed but the preload is maintained Removing the major load allows partial

recovery and reduces the depth of penetration The permanent increase in depth of penetration resulting

from the application and removal of the major load is used to calculate the Rockwell number using the

relation

HR = E ndash e

Where E is a constant depending on the form of the indenter 100 units for diamond indenter and 130

units for steel ball indenter e is the permanent increase in depth of penetration due to the major load

measured in units of 0002mm

Fig 2-7 Rockwell Indentation

When testing materials indentation hardness is related linearly to the tensile strength The important

relation permits economically important nondestructive testing of bulk metal deliveries with lightweight

equipment like the Rockwell tester shown below in figure 2-7

Fig 2-8 Rockwell Hardness Tester

20

There are different scales denoted by a single letter that use different loads or different indenters

The result is a dimensionless number denoted as HR X where X will be the letter denoting the scale as

shown below in table 2-1

Table 2-1 Rockwell Hardness Test Scale

Differential depth hardness measurement was first conceived in 1908 by Viennese professor Paul

Ludwik It eliminated the errors associated with the mechanical imperfections of the system such as

backlash and surface imperfections in the specimen Rockwell testing has an advantage over Brinell

testing because the latter was slow itrsquos not useful on fully hardened steel and left too large an impression

to be considered nondestructive

The tester was co-invented by Hugh M Rockwell and Stanley P Rockwell The requirement for this

tester was to quickly determine the effects of heat treatment on steel bearing races

21

223 Vickers Hardness Test HV

This is a type of microindentation hardness test where a diamond indenter of specific geometry is

impressed into the surface of the test specimen using a known applied force ranging from 10 to 1000

grams This type of tests usually has forces of 2N and produce indentations of about 50μm They can be

used to observe changes in hardness on the microscopic scale It is difficult to standardize the

microhardness measurements because it has been found that the microhardness of almost any material is

higher than its macrohardness The values also vary with load and work-hardening effects of materials

The Vickers test is often easier to use than other hardness tests because the required calculations are

independent of the size of the indenter and the indenter can be used for all materials It can be used for all

metals and has one of the widest scales among hardness tests The unit of the Vickers test is denoted as

HV and can be converted to units of Pascal (Pa) but it is not a measurement of pressure The hardness

number is determined by the load over the surface area of the indentation and not the area normal to the

force

A square-based pyramid shaped diamond is use as the indenter It has been established that the ideal

size of a Brinell impression was 38 of the ball diameter As two tangents to the circle at the ends of a

chord 3d8 long intersect at 136plusmn05deg it was decided to use this as the angle of the indenter giving an

angle to the horizontal plane of 22deg on each side The HV number is determined by the ratio FA where F

is the force applied to the diamond in kgf and A is the surface area of the resulting indentation in mmsup2 A

can be determined by the relation

A =

Where A is the surface area of indentation and d is the average length diagonal left by the indenter

This can be approximated as

A =

Then the Vickers Number is

HV =

=

Vickers hardness number is reported as xxxHVyy or xxxHVyyzz (if duration of applied force differs

from 10s to 15s) where xxx are replaced by the hardness number yy is the load in kg and zz indicates

loading time The values are generally independent of test force

The test was developed in 1921 by Robert L Smith and George E Sandland at Vickers Ltd as an

alternative to Brinell method to measure the hardness of materials

22

Fig 2-9 Vickers Indentation Fig 2-10 Vickers Hardness Tester

23 AR Coating

231 Bose-Einstein Condensate

The Bose-Einstein Condensate or BEC is a state of matter of a dilute gas of bosons cooled to

temperatures very near absolute zero around 0K or -27315degC Under such conditions a large fraction of

the bosons occupy the lowest quantum state where the quantum effects become apparent on a

macroscopic scale This gave birth to the Bose-Einstein Statistics which are the rules that govern the

behavior at this state It is one of the two possible ways in which a collection of indistinguishable particles

may occupy a set of available discrete energy states The aggregation of particles in the same state

accounts for the cohesive streaming of laser light and the frictionless creeping of superfluid helium (an

application discussed later) Bose and Einstein recognized that a collection of identical and

indistinguishable particles can be distributed this way This theory applies only to those particles not

limited to single occupancy of the same state particles that do not obey the Pauli Exclusion Principle

restrictions Such particles are the Bosons named after the statistics that correctly describe their behavior

This phenomenon was first predicted by Satyendra Nath Bose around 1924 when he considered how

groups of photons behave He then asked Albert Einstein for help publishing his discoveries to which

Einstein agreed and gave follow up supporting these findings The resulting efforts became the concept of

a Bose gas governed by the Bose-Einstein Statistics described above Einstein demonstrated that cooling

bosonic atoms to a very low temperature would cause them to condense into the lowest accessible

quantum state resulting in a new form of matter

The first gaseous condensate we produced by Eric Cornell and Carl Wieman at the University of

Colorado at Boulder NIST ndash JILA lab sung a gas of rubidium atoms cooled to 170 nK which earned

them the 2001 Nobel Prize in physics together with Wolfgang Ketterle from MIT The transition to BEC

occurs below a critical temperature which for a uniform three dimensional gas consisting of

non-interacting particles with no apparent internal degrees of freedom is given by

23

Tc =

(

)

asymp 33125

Where Tc is the critical temperature n is the particle density m is the mass per boson h is the

reduced Planck constant k is the Boltzmann constant and ζ is the Riemann zeta function

There are two classes of elementary particles defined by whether their quantum spin is a nonnegative

integer or an odd half integer A Bose-Einstein Condensate is shown below in figure 2-11

Fig 2-11 Bose Einstein Condensate at different scales

Bosons are the particles whose quantum spin is a nonnegative integer (s = 0 1 2 etc) Examples of

bosons include fundamental particles (Higgs Boson Photons W and Z Bosons Gluons Gravitons etc)

composite particles (Mesons Hadrons Nuclei and Atoms of Carbon-12 and Helium-4) and

quasi-particles Bosons are considered force carrier particles The Bosons differ from Fermions in that

there is no limit to the number that can occupy the same quantum state This is called the Pauli Exclusion

Principle

The Pauli Exclusion Principle says that no two identical fermions may occupy the same quantum state

simultaneously in other words this means that the total wave function for two identical fermions is

anti-symmetric with respect to exchange of the particles This means that no two electrons in a single

atom can have the same four quantum numbers

Fermion is any particle characterized by Fermi-Dirac Statistics and follows the Pauli Exclusion

Principle described above Quarks Leptons and composite particles (Hadrons Nuclei and Atoms of

Carbon-13 and Helium-3) made of an odd number of these are considered Fermions It can be an

elementary particle such as the electron or a composite particle such as the protons Following the Pauli

24

Exclusion Principle only one fermion can occupy a particular quantum state at any given time If multiple

fermions have the same spatial probability distribution then at least one property of each fermion must be

different Fermions are usually associated with matter because composite fermions are key building

blocks of matter (neutrons and protons)

Fermionsrsquo behavior by the Fermi-Dirac Statistics which describes the energies of single particles in a

system comprising of many identical particles It applies to identical particles with half-odd integer spin

in a system of thermal equilibrium The particles in the system are assumed to have negligible mutual

interaction This allows the many-particle system to be described in terms of single-particle energy states

The result is the Fermi-Dirac distribution of particles over these states and includes the condition that no

two particles can occupy the same state which has considerable effect on the properties of the system

In quantum mechanics the position of an object is uncertain An object has a definite probability of

being at any given point in space This probability is encoded in the wave function mentioned earlier If

one concentrates a large number of identical bosons in a small region then it is possible for their wave

functions to overlap so much that the bosons lose their identity When this happens thatrsquos a Bose-Einstein

Condensate It is only possible at very low temperatures because at high temperatures the individual

bosons have small wave functions and move rapidly which causes them to fly apart

For now applications are still restricted because there are still some setbacks regarding BECs They

are extremely fragile they are being produced in small quantities with just a few million atoms at a time

and finally they can only be made from certain types of atoms Some examples are the atom laser Ketterle

in which a conventional light lase emits a beam of coherent photons this means they are all in phase and

can be concentrated to an extremely small bright spot BECs can slow down light as demonstrated by

Prof Lene Hau PhD in 2001 by the use of a superfluid [7] These manipulations could develop into

new types of telecommunications technology optical storage and quantum computing

BECs are related to super-fluidity and super-conductivity Super-fluidity is the state of matter in

which the behavior is that of a fluid with zero viscosity It was discovered in liquid helium but now it has

applications in astrophysics high-energy physics and theories of quantum gravity

Super-conductivity is a phenomenon of exactly zero electrical resistance and expulsion of magnetic

fields occurring in certain materials when cooled below a characteristic critical temperature A

super-conductor is shown below in figure 2-12

Fig2-12 Super Conductor

25

232 AR Coating Basic Principles

Anti-reflective (AR) coating is a type of optical coating applied to the surface of lenses and other

optical devices (in our case we planned to apply it to a laser diode) to reduce reflection This improves

the efficiency of the system since less light is lost The primary benefit is the elimination of the reflection

itself

When light the medium (glass) it will produce reflection if 100 of the light comes from the air and

enters the glass because therersquos a difference between the index of refraction some of the light will go out

and when the light is coming out of the glass into the air once again because of the difference between

index of refraction some of the light wonrsquot be able to pass through the medium

When the light makes the first trip into the glass there was a loss of about 4 in the reflection and

when the light makes the trip back outside there was another loss of about 4 so when we assume that

100 of the light interacts with the medium actually therersquos just about 92 acting (we neglect the light

absorbed by the glass around 05) To illustrate this idea please refer to figure 2-13

Fig 2-13 Simple Model for Light in Glass Medium

When we apply the AR Coating the light that enters will only have a loss of about 05 and when

making the trip back outside again only 05 of light is loss so we get the result of increasing the light

passing through up to 99 (again neglecting the light absorbed by the glass around 05) To illustrate

this idea please refer to figure 2-14

26

Fig 2-14 Simple Model for Light in Glass Medium after AR Coating

The AR Coating can reduce reflection of incoming light In the case that light hits perpendicular to

the surface of the medium the intensity of the reflection can be calculated using the Reflection

Coefficient

Where n0 and ns are the refractive indices of the first and second media respectively The value of R

varies from 0 (no reflection) to 1 (all light reflected) and is usually quoted as a percentage

Complementary to R is the transmission coefficient or Transmittance If absorption and scattering are

neglected then the value of Transmittance is always 1-R then if a beam of light with intensity I is

incident on the surface a beam of intensity RI is reflected and a beam with intensity TI is transmitted to

the medium

The optimal value is called the Optimal Index of Refraction and is described as

For glass with ns around 15 in air (n0 around 10) then the optimum refractive index will be n1 =

1225

To reduce the refraction in this case we now mean the one that is produced inside the chamber of the

Laser diode the easiest way is to apply a low reflectivity AR coating on the surface of the laser To

measure the appropriate thickness of the coating layer we can use the equations described above By

applying a coat exactly

thickness film we can assure that a certain wavelength is transmitted The

27

reflected waves from the back of the glass medium will be half a wavelength out of phase So they

interfere destructively Because all reflected waves are interfered the maximum amount of light passes

through the coating Please refer to figure 2-15 to illustrate this idea

Fig 2-15 Light Passing through AR Coat and Glass

The most common process to attain this final product is by vacuum deposition For the best coating

results we need to lower the pressure inside the vacuum system to torr

Fig 2-16 Lens without (Top) and With (Bottom) AR Coating

28

233 Laser Diode Basic Principles

A laser diode is a laser whose active medium is a semiconductor similar to that found in

light-emitting diodes (LEDs) Please refer to figure 2-17 The most common type of laser diode is formed

from a p-n junction and powered by injected electric current

Fig 2-17 Laser Diode

Laser diodes are formed by doping a very thin layer on the surface of a crystal wafer The crystal is

doped to produce the n-type region and a p-type region one above the other

By referring to figure 1-2 we can see the basic structure of a working laser When the laser diode has

a current passing through it the light will get excited inside its gain medium and then will start to

resonate this process is called pumping The current exceeds the critical current and then it comes out as

laser light Please refer to figure 1-3 Since we use an external cavity laser we need to apply the AR

coating to the diode and adjust a diffraction grating The laser light comes out the diode and bounces on

the grating making the resonance externally and this becomes the ldquocavityrdquo as shown in figure 2-18

Fig 2-18 Tunable Laser Basic Configuration

29

The most important feature of the external cavity laser is that we can adjust the wavelength easily just

by changing the diffraction gratingrsquos angle and in the end this is the output wavelength of the laser For

different wavelengths there will be different levels of visible light as shown in figure 2-19

Fig 2-19 Light Spectrum

234 Quartz Microbalance System

A Quartz Crystal Microbalance is an instrument that measures a mass per unit area by measuring the

change in frequency of a quartz crystal resonator The resonance is disturbed by the addition or removal

of a small mass due to oxide growthdecay or film deposition (which is the case in our study) at the

surface of the acoustic resonator The QCM can be used under vacuum in gas phase and more recently in

liquid environments It is useful for monitoring the rate of deposition in thin film deposition systems

under vacuum Frequency measurements are easily made with high precision

For our research we used the Sigma Instruments SQM-160 RateThickness Monitor shown in figure

2-20

Fig 2-20 Front and Back Panels of SQM-160

30

The microbalance uses Quartz as the resonator Quartz is one member of the family of crystals that

experience the Piezoelectric Effect

Piezoelectricity is the charge that accumulates in certain solid materials in response to applied

mechanical stress It means electricity resulting from pressure It was discovered in 1880 by Jacques and

Pierre Curie It is understood as the linear electromechanical interaction between the mechanical and the

electrical state in crystalline materials with no inversion symmetry It is a reversible process in that

materials exhibiting direct piezoelectricity also exhibit the reverse This means that the internal generation

of electrical resulting from applied mechanical force and vice versa

By using the piezoelectric effect we can probe as an acoustic resonance by electrical means Applying

alternating current to the quartz crystal induces oscillations This creates a shear wave We can use these

qualities to determine the resonance frequency at high accuracy

The frequency of oscillation of the crystal is partially dependent in the thickness of the crystal During

normal operation all the variables are held constant so a change in thickness correlates directly to a

change in frequency As mass is deposited or etched away the thickness increases or decreases and so the

frequency of oscillation changes accordingly With some simplifying assumptions the frequency change

can be quantified and correlated precisely to the mass change using the Sauerbreyrsquos Equation

Developed by G Sauerbrey in 1959 it is a method for correlating changes in the oscillation

frequency of a piezoelectric crystal with the mass deposited on it It is defined as below

Where f0 is the Resonant frequency Δf is the Frequency change Δm is the mass change A is the

piezoelectrically active area of the crystal q is the Density of quartz (2648 gcmsup3) and μq is the Shear

modulus of quarts(2947x gcmssup2)

Because the film is treated as an extension of thickness Sauerbreyrsquos equation only applies to systems

in which the following 3 conditions are met

Deposited mass must be rigid

Deposited mass must be distributed evenly

The frequency change

lt002

If the change is greater than 2 the Z-match method must be used to determine the change in mass

It is defined as

Where fL is the frequency of the loaded crystal fU is the resonant frequency Nq is the frequency

constant (1668x HzAring) Δm is the mass change A is the piezoelectrically active area of the crystal

31

q is the density of quartz Z is the method constant f is the density of film μq Is the shear modulus of

quarts and μf is the shear modulus of film

The Sauerbrey equation cannot be applied to systems under liquid medium

The crystals are seed crystals plated with gold on both top and bottom for applications A crystal is

shown in figure 2-21 The QCM consists of a thin piezoelectric plate with electrodes evaporated on both

sides Due to the piezoelectric effect AC voltage across the electrodes induces a shear deformation and

vice versa The electromechanical coupling provides a simple way to detect an acoustic resonance by

electrical means

The Z also called Z-factor is a constant value for different materials and it is shown together with the

density of different materials in table 2-2 below

Fig 2-21 QCM Crystals

The Oscillator of the SQM-160 is shown in figure 2-22 and the equivalent circuit for the Resonant

Oscillator is shown in figure 2-23

Fig 2-22 SQM-160 Oscillator

32

Fig 2-23 Oscillator Circuit

33

Table 2-2 Z-Ratios for Different Materials

Table 2-2 Continued

34

Table 2-2 Continued

35

Table 2-2 Continued

36

Table 2-2 Continued

37

Table 2-2 Continued

38

Table 2-2 Continued

235 Vacuum Chamber System

Vacuum Evaporation is the process of depositing thin films of materials onto surfaces The technique

consists of pumping a vacuum chamber to pressures of less than torr and heating a material to

produce a flux of vapor in order to deposit the material onto a surface The material to be vaporized is

typically heated until its vapor pressure is high enough to produce a flux several Angstrom per second by

using an electrically resistive heater or bombardment by a high voltage beam The process was invented

by Henri Nestle in 1886 for food industry

In here the system has been pumped to a vacuum of Torr When a high current is passed

through the filament boat the filament boat is heated over the desired metal evaporation temperature and

so evaporation starts When the evaporation process is finished and the metal cools down crystals

condensate in the surface of the wafer From the weight of the evaporated material the distance between

the filament boat and the wafer we are able to calculate the deposition thickness and we can also use the

mass detector follower like the Quartz crystal resonator microbalance system In the process of

evaporation we usually use a board in between the filament boat and the wafer This is because before we

arrive to the desired evaporation temperature there will be some impurities that will be vaporized in the

controlled environment so we first use a small current and the board in between to get rid of those

impurities and this raises the purity of the deposition material

39

A vacuum evaporation system is shown in figure 2-24

Fig 2-24 Vacuum Evaporation System

Rough Vacuum 760 ~ 1 torr

Medium Vacuum 1 ~ torr

High Vacuum ~ torr

Ultra-High Vacuum Lower than torr

Table 2-3 Classification of Vacuum

For our study we need to use a Turbo Pump A regular turbo pump is shown in figure 2-25

Fig 2-25 Turbo Pump

For our research we used the Pfeiffer TCP 015 Electronic Drive Unit and Granville Phillips 375

Convectron shown below in figure 2-26

40

Fig 2-26 Control and Measurement Equipment

The electronic drive controls the turbo pump and the Convectron measures the pressure inside our

chamber The turbo pump is a type of vacuum pump used to maintain high vacuum Most turbo pumps

are centrifugal When we start the pumping we need to use a mechanical pump so as to decrease the

pressure inside the system from constant atmospheric pressure to torr and then the use dispersion

pump to continue the vacuum until we get to the desired pressure We need to notice though when we

start the dispersion pump we canrsquot turn off the mechanical pump and they both need to run together If

we need to turn off the pumping we first turn off the dispersion pump wait for it to completely stop and

then turn off the mechanical pump

Our completely assembled system is shown in figure 2-27 below

Fig 2-27 Complete System

41

Chapter 3 TENSILE TESTING IN DEPTH

31 Experimentrsquos Purpose and Principles

By means of Universal testing machine and Strain gauges we were able to observe discuss and

analyze the phenomena created when a specimen of certain material is manipulated under an external load

and determine the stress strain and deformation values later we can use the graphing methods of

stress-strain diagram to describe it

The main point of this experiment is that after the tensile specimen is tested use computer analysis

and the actual strain data and after statistical adjustment make the final results report (Tensile testing

experiment is in accordance with ASTM E8)

32 Experimentrsquos Equipment

321 Universal Testing Machine

For the materials testing experiment part of this research we use a Universal Testing Machine as

shown in figure 31 The maximum load it can apply is 100 Ton After the test specimen is secured on the

device with the use of instrumentation the load exerted and the effects of this become apparent on the

specimen and even the smallest of changes can be recorded For our research we used the Chun Yen

Testing Machines Co Ltd 100 Ton Micro Computer Universal Tensile Tester

Fig 31 Universal Testing Machine

42

Table 31 shows the specifications for this machine

Max Capacity 100 Ton

Accuracy plusmn1

Tension (mm) Max Space 1150mm

Grip for Rod 20-70mm

Ram Stroke 250mm

Effective Column Interval 940mm

Crosshead Speed 300mmmin

Testing Speed 0-50mmmin

Volume of Machine 1700times1000times3350mm(LtimesWtimesH)

Volume of Control Panel 1000times800times1500mm(LtimesWtimesH)

Weight 8000kg

Power 3∮220V 20A

Computer AMD K6-2-350

OS Windows XP

Screen 15rdquo CRT

Table 3-1 Chun Yen Testing Machine Specs Table

The connections diagram is shown in figure 3-2

Fig 3-2 Diagram for System Connections

43

When the test specimen is placed when the external force is applied the Load Cell can measure the

size of the applied force and the Encoder measures the expansion rate of change The Local Controller

receives all the information from the 2 units after arranging the results they are displayed in the

computer and they can be afterwards submitted for more complex analysis such as Finite Element

Analysis and we can get the Stress-Strain Diagram

322 Strain Measurement Equipment

The equipment used in our research provides a four-channel measurement that means we can use up

to 4 strain gauges at a time to do our measurements and provides 3 different bridge arrangements as

shown in figure 3-3

(a) (b) (c)

Fig 3-3 Input Connections for Strain Indicator

Figure 3-3 (a) is the Quarter Bridge (b) is the Half Bridge and (c) is the Full Bridge and Transducers

For our study we used the Quarter Bridge and use the Strain Gauge values to decide the position of the

connecting wires The Strain indicator is shown in figure 3-4

Fig 3-4 Vishay Micro-Measurements Model P3 Strain Indicator and Recorder

44

Input Connections Tool Free eccentric lever release

4-channel input

Wire diameter16-28AWG

Bridge Configurations Quarter- Half- and Full Bridge

Bridge Impedance 60-2000Ω

Display 128 64 pixel FSTN positive gray LCD

Data Conversion AD Converter filter

Measurement Range Resolution Strain Range plusmn155mVV

Resolution plusmn00005mVV

Measurement Accuracy plusmn01 of reading plusmn3 counts

Gage Factor Control 0500-9900

Balance Control Software either manual or automatic

Bridge Excitation 15VDC nominal

Communication Interface USB Cable Included

Data Storage Removable Media Card

Shunt Calibration Across bridge completion resistors controlled

by software When Gage Factor=200

120Ω350Ω1000Ω

Analog Output Value 0 to 25V max

Ranges plusmn320 microε plusmn3200 microε plusmn32000 microε

Error 05 output voltage +5mV

Max Error 14 output voltage + 20mV

Update rate 480 samplessec

Output Load 2000Ω

Power Battery Two Alkaline D cells

Battery life 400 hours typ

USB 5V 100mA

Operational Environment Temperature 0-50

Humidity Up to 90 Non-condensing

Case Aluminum Alloy

Size and Weight 228times152times152(mm) 20(kg)

Table 3-2 Vishay Micro-Measurements Model P3 Strain Indicator and Recorder Specs

45

323 Strain Gauge

The strain gaugersquos main basic principle is to use a resistancersquos characteristics to measure the strain

The inside connections of the strain indicator are shown in figure 3-5

Fig 3-5 Inner Connections

As shown above this is a quarter-bridge connection We connect equal-length 3 wires to the 2

connections allowed by the strain gauge wire 1 and 3 can be used to cancel out the effects of temperature

to the resistance and because of the addition of wires 1 and 3 wire 2 can directly measure the experiment

results from the strain gauge and therefore the strain developed with no influence of temperature

If there were no two measuring leads then the relations will be

R 4 =R g +2R L

Where Rg is the Strain Gauge Value and RL is the wire resistance then

4

4

R

R=

Lg

g

RR

R

2

=

gL

gg

RR

RR

21

amp

4

4

R

R=

g

g

R

R(1- L)

Where L is the Signal Loss Factor and so

L =gL

gL

RR

RR

21

2

g

L

R

2R if

g

L

R

2Rltlt1

46

(Actual Value R g =120R L =08g

L

R

2Ris always much smaller than 1)

R 4 =R g +2R LR 2 =R 3 =rR gR 1 =R g 32 RR =0

V 0 =V 2)1( r

r

(

4

4

R

R-

1

1

R

R)

The first term describes loss attenuation effects second term describes loss of balancing capabilities

effects

V 0 =V 2)1( r

r

[

)2

(Lg

g

RR

R

+

T

Lg

g

RR

R

)

2( + T

Lg

L

RR

R

)

2

2( -(

g

g

R

R) T ]

The first term describes loss attenuation effects and loss of balancing capabilities effects the second

third and fourth terms describe the temperature effects on the wire

For the three-wire method we have

L =gL

gL

RR

RR

1

g

L

R

R if

g

L

R

Rltlt1

V 0 =V 2)1( r

r

[

)(Lg

g

RR

R

+

T

Lg

g

RR

R

)( + T

Lg

L

RR

R

)

2( -

T

Lg

g

RR

R

)( - T

Lg

L

RR

R

)

2( ]

V 0 = V2)1( r

r

)(

Lg

g

RR

R

In the last four terms inside parenthesis we can see the effects of temperature being cancelled out and the

effect on first term is not great so this is the reason why in our research we use three wires

47

324 Specimen Measurements

The tensile specimens used in this research are compliant of ASTM E8 Tensile parameters as shown

in figure 3-6

Fig 3-6 Tensile Specimen

Diameter

D(mm)

Gauge

Length

G(mm)

Smallest

Arc

Radius

R(mm)

Shortest

Area

A(mm)

Total

Length

L(mm)

Clamping

Area

Length

B(mm)

Clamping

Area

Diameter

C(mm)

Bar 125 02 625 01 gt10 gt75 ~ 145 ~ 35 20

Table 3-3 Specifications for Round Bar

33 Experiment Procedure

1 Attaching the Strain Gauge to the Tensile Specimen

(1) Prepare 1 ASTM E8 compliant tensile specimen round bar as shown in figure 3-7

(2) Prepare Strain Gauge as those described in table 3-4

(3) Prepare other consumables and adhesive agent such as epoxy adhesive or

cyanoacrylate adhesive as shown in figure 3-8

48

Fig 3-7 Actual Tensile Specimen

Fig 3-8 Other Materials Used (Such as Alcohol gauze transparent tape adhesive)

Gage Type

EA-06-120LZ-120E

Resistance in ohms at 24∘C

1200plusmn03

Gage Factor at 24∘C

2075plusmn05

Transverse Sensitivity at 24∘C

(+07plusmn02)

Table 3-4 Specifications for Strain Gauge

2 Attaching Strain Gauge

As shown in following figures we shall explain the attachment of the strain gauge

(1) Use sand paper and a rasp to clean thoroughly the surface where the strain gauge will be

attached to

49

(a)

(2) Use alcohol to wash the surface where the strain gauge will be attached and use gauze to rub

it off

(b)

(3) Find a clean surface and clean it with alcohol and gauze

(c)

(4) Place the strain gauge in the clean surface Use a piece of transparent tape on top of the strain

gauge after securely placed rip it off the surface carefully

50

(d)

(5) Use a piece of white paper to mark the place where the strain gauge will be attached and in

this way we can make sure that the strain gauge will be placed as horizontally and vertically

correct as possible

(e)

(6) In the place where we had our mark place the strain gauge

(f)

(7) Carefully lift one side of the tape and apply some of the adhesive agent to both the strain

gauge and specimenrsquos surface

(g)

51

(8) We need to make sure that the gauge and the specimen will be firmly attached so we gently

apply pressure with our thumb

(h)

(9) After the adhesive is fully dry we can carefully rip off the tape

(i)

(10) We need to do the whole process twice one for the horizontally placed strain gauge and one

for the vertically placed strain gauge

52

(j)

(11) We now proceed to solder the wires to the strain gauge

(k)

(12) After soldering we use a Volt Multimeter to measure that there is no contact between wires

If there is none then the specimen is ready for testing

(l)

(13) We now need to measure a 5cm distance and mark it to check and compare the elongation

before and after the tensile testing

(m)

53

Fig 3-9 Specimen-Strain Gauge Process

3 Tensile Test

(1) Enter the computer application that controls the tensile testing machine

(2) Turn on the tensile testing machine main switch

(3) Adjust the hydraulic pump to go back to its original position

(4) Bring the lowering motor down to a distance enough so as to attach the tensile specimen to the

system open the clamps and secure the specimen

(a)

(5) Connect all the necessary wires to the strain indicator equipment

54

(b)

(6) Start the ascending motor and wait for the expansion

(c)

Fig 3-10 Specimen-Tensile Testing Process

4 Start the Test

(1) Enter the software application and enter some variables needed for the experiment in the

specific screen

(2) Go back to the main screen and press the [測試] (measure) button to start the test and auto

recording in the software

(3) After the specimen breaks the mechanical device will automatically stop and ask the user to

enter the total displacement We take out the specimen from the testing machine and adjust the

machinersquos position back to its original position

(4) Save the results information

(5) Record the results from the strain indicator

34 Results

From this experiment we can get the Poissonrsquos Ratio Youngrsquos Modulus and Yield Strength etc and

because of the slippage phenomenon in the clamp at the moment of the test then the Elastic Limit will

display some yield phenomena So omit any undesirable results we just take the Yield portion of the

results as reference

In the process of the experiment the most important part to attend to is the attaching of the strain

gauge because the gaugersquos purpose is to measure the strain developed during the test and this strain

might be very small If the gaugersquos angle change during the test ie is not well attached this will affect

the accuracy of the measurements of Poissonrsquos ratio and Youngrsquos modulus

55

The materials provided by the manufacturer are SUM 23 and SUM 43 steel round bars and these two

types of materials have been through different heat treatment processes so they can be sub-divided

further into untreated material heat-treated material and black surface heat treated material for the two

materials with heat treatment the treatment process and finished are different In the end we only have

the mechanical properties that were calculated after our research of these materials

All of the specifications are identical to those shown in figure 3-6

341 SUM 23

Fig 3-11 SUM 23 Untreated Material

Number 7 10

Hardness(HRB) 74 75

Yield Stress (MPa) 448 440

Tensile Strength (MPa) 544 560

Poissonrsquos Ratio 029 027

Youngrsquos Modulus (GPa) 203 210

Cut-off Area Shrinking () 42 41

Elongation () 1125 1011

Table 3-5 Mechanical Properties of SUM 23 Untreated

56

Stress-Strain Diagram

(a)

(b)

57

Fig 3-12 Stress-Strain Diagrams for (a) 7 Round Bar and (b) 10 Round Bar

Cut-Off Area

(a)

(b)

Fig 3-13 Cut-Off Area of (a) 7 Round Bar and (b) 10 Round Bar

58

SUM 23 Nickel Round Bar

Fig 3-14 SUM 23 Nickel Material

Number 1 2 3 4

Hardness(HRB) 48 50 49 48

Yield Stress (MPa) 370 370 380 400

Tensile Strength (MPa) 455 451 450 450

Poissonrsquos Ratio 028 046 029 026

Youngrsquos Modulus (GPa) 243 303 246 206

Cut-off Area Shrinking () 803 803 726 601

Elongation () 566 65 602 647

Table 3-6 Mechanical Properties of SUM 23 Nickel

59

Stress-Strain Diagram

(a)

60

(b)

(c)

(d)

61

Fig 3-15 Stress-Strain Diagrams for (a) 1 Round Bar (b) 2 Round Bar (c) 3 Round Bar and (d)

4 Round Bar

Cut-Off Area

(a)

(b)

62

(c)

(d)

Fig 3-16 Cut-Off Area of (a) 1 Round Bar (b) 2 Round Bar (c) 3 Round Bar and (d) 4 Round

Bar

63

SUM 23 Black Surface Round Bar

Fig 3-17 SUM 23 Black Surface Material

Number 1 2 3

Hardness(HRB) 51 50 51

Yield Stress (MPa) 378 371 369

Tensile Strength (MPa) 467 465 464

Poissonrsquos Ratio 03 016 04

Youngrsquos Modulus (GPa) 215 266 266

Cut-off Area Shrinking () 986 94 848

Elongation () 748 805 761

Table 3-7 Mechanical Properties of SUM 23 Black Surface Material

64

Stress-Strain Diagram

(a)

(b)

65

(c)

Fig 3-18 Stress-Strain Diagrams for (a) 1 Round Bar 2 Round Bar and (c) 3 Round Bar

Cut-Off Surface

(a)

66

(b)

(c)

Fig 3-19 Cut-Off Surface of (a) 1 Round Bar 2 Round Bar and (c) 3 Round Bar

67

342 SUM 43

Fig 3-20 Untreated SUM 43 Untreated Material

Number 1 5

Hardness(HRB) 76 75

Yield Stress (MPa) 572 594

Tensile Strength (MPa) 743 785

Poissonrsquos Ratio 027 029

Youngrsquos Modulus (GPa) 200 202

Cut-off Area Shrinking () 338 2944

Elongation () 857 894

Table 3-8 Mechanical Properties of SUM 43 Untreated

68

Stress-Strain Diagrams

(a)

(b)

Fig 3-21 Stress-Strain Diagrams for SUM 43 (a) 1 Round Bar and (b) 5 Round Bar

69

Cut-Off Area

(a)

(b)

Fig 3-22 Cut-Off Area of SUM 43 (a) 1 Round Bar and (b) 5 Round Bar

70

SUM 43 Nickel Round Bar

Fig 3-23 SUM 43 Nickel Material

Number 4 5

Hardness(HRB) 51 50

Yield Stress (MPa) 1580 1544

Tensile Strength (MPa) 1639 1625

Poissonrsquos Ratio 03 028

Youngrsquos Modulus (GPa) 194 201

Cut-off Area Shrinking () 1697 137

Elongation () 376 265

Table 3-9 Mechanical Properties of SUM 43 Nickel

71

Stress-Strain Diagrams

(a)

(b)

Fig 3-24 Stress-Strain Diagrams for (a) 4 Round Bar and (b) 5 Round Bar

72

Cut-Off Area

(a)

(b)

Fig 3-25 Cut-Off Area of (a) 4 Round Bar and (b) 5 Round Bar

73

SUM 43 Black Surface Material

Fig 3-26 SUM 43 Black Surface Material

Number 3 5

Hardness(HRB) 56 56

Yield Stress (MPa) 1416 1361

Tensile Strength (MPa) 1591 1402

Poissonrsquos Ratio 029 031

Youngrsquos Modulus (GPa) 200 202

Cut-off Area Shrinking () 139 124

Elongation () 24 24

Table 3-10 Mechanical Properties of SUM 43 Black Surface Material

74

Stress-Strain Diagrams

0 2 4 6 8 10 12 14

-200

0

200

400

600

800

1000

1200

1400

1600

1800

應力 (MPa)

應變()

(a)

0 2 4 6 8 10

-200

0

200

400

600

800

1000

1200

1400

1600

應力

(MPa)

位移 ()

(b)

Fig 3-27 Stress-Strain Diagrams for (a) 3 Round Bar and (b) 5 Round Bar

(Note These curves were formulated using Visual Solutions Inc VisSim Software)

75

Cut-Off Area

(a)

(b)

Fig 3-28 Cut-Off Area of (a) 3 Round Bar and (b) 5 Round Bar

76

The force value (N) was retrieved from the Universal Testing Machine

The Poissonrsquos Ratio (ε) is calculated as

ε =

the values for the Poissonrsquos Ratio are in average around 0297

The Youngrsquos Modulus (E) is calculated as

E =

Where

Stress =

Cross-sectional Area =

where D is the Diameter

The value for D was in average around 1258 mm

The values shown by the computer because there is Slippage phenomena between the Clamp and the

specimen will not be taken into consideration for the elongation strain and Youngrsquos modulus and we will

refer to the values that we have meticulously calculated

77

Chapter 4 AR COATING IN DEPTH

41 Experimentrsquos Purpose and Principles

By means of a vacuum chamber and several other instruments we intend to apply Anti-Reflective

Coating using deposition process to a laser diode and in this way reduce its refraction so as to make it

lose less light in the process of amplification and we can control certain wavelengths we want produced

for certain desired applications in our case we are attempting to re-create a Bose-Einstein Condensate

An optimal BEC apparatus is shown in figure 4-1

Fig 4-1 BEC Apparatus

The main point of this experiment is to build a vacuum chamber system attach all the instrumentation

needed (Vacuum pump deposition meter and voltmeter) and use it to apply AR coating to a laser diode

After we have accomplished the AR coating other team will be in charge of designing the BEC apparatus

and use the results of our research

78

42 Experimentrsquos Equipment

421 Vacuum Chamber

For this research we designed a vacuum chamber whose main body is shown in figure 4-2 Its

dimensions are

Width 240 mm

Length 240 mm

Height 200 mm

Outer Diameter 4 in

Inner Diameter 15 in

Fig 4-2 Vacuum Chamber Main Body

The chamber is made up of 6 pass ways pass way A is the connection with the Laser Deposition

Equipment pass way B is the connection with the Turbo Pump and pass way C is for the connection with

the Deposition Source

A

C

B

79

Pass way C is for the deposition source as mentioned above This is a system where a thermal

resistance is heated by passing a high current through it which heats up a filament boat (made of tungsten)

where the material to be evaporated is place We control the temperature as such that the material will

evaporate and the heat will not cause the filament boat to crack

Because P = Isup2 R (where P is power I is current and R is resistance) to avoid the current to flow

where it is not desired we decided that the material for the Thermocouple shown in figure 4-3 should be

Copper ᴓ 63 mm We choose it that way because Copper has very good heat dissipation characteristics

and the resistance value is low It can reduce the value of the current enough to make the thermocouple to

create heat

Fig 4-3 Thermocouple

To the thermocouple we attach the tungsten filament boat We need to take notice of materials to be

used in this design because when using high current the tungsten filament boar will heat up and so the

material must be able to keep up with the heating potential of tungsten and has a low coefficient of heat

dissipation to avoid the tungsten to fail when heating up and therefore not evaporating Considering all

this we decide to use Stainless Steel

Because this clamp will be assembled inside the chamber after many revisions it was determined it

will have the shape shown in figure 4-4

Fig 4-4 Filament Boat Clamp Design

80

For the tungsten filament boat we bought the product from a distributor The dimensions are

Length 100 mm

Width 10 mm

Height 1 mm

Our thermocouple is 15 in but the pass way C is 4 in so we need to attach a Flange that connects

15in to 4in Because these specifications are quite difficult to achieve by Milling we had to use

electrical wire cutting

For the laser clamping system where the laser that is going to be AR coated will be placed will be

connected to pass way A the assembly is shown in figure 4-5 below

Fig 4-5 Cover Assembly

For this design we used an O-ring instead of a gasket so as to save time The design of the assembly

where the laser will be placed is shown in figure 4-6

Fig 4-6 Upper Cover Inner Assembly

D

E

F

81

Point D is the plate in the assembly where the laser diode will be fixed Because of the easy

processing we decide to use Aluminum and it is screwed to the top cover Point E is the connection for

the Quartz crystal resonator and it is designed in the same as point F in this way the results of the quartz

microbalance system will be more accurate in real time Point F is the final resting place for the laser

diode We use a Thor Labs Base with dimensions of ᴓ 9mm and ᴓ 56mm for two different size laser

diodes It just needs to be plugged in for easy installation

From figure 4-6 we know that the system needs signal system connections and because of the

change in temperature inside the chamber this could affect the functioning of the quartz microbalance so

we also need to install water tubes for cooling This is shown in figure 4-7 below

Fig 4-7 Diagram of Upper Cover Connections

In figure 4-8 we show the Feed through connections and their functions

Fig 4-8 Feed through Diagram

82

1 SQM-160 wire 5 Laser Connection 1 (Vin)

2 SQM-160 (G) 6 Laser Connection 2 (G)

3 K-Type-1 7 Laser Connection 3 (PD)

4 K-Type-2 8 Not In Use

The fully assembled chamber is shown in figure 4-9

Fig 4-9 Fully Assembled Chamber

422 Quartz Crystal Microbalance

For measuring the deposition on our target for coating we used the Inficon SQM-160 RateThickness

Monitor It is an easy to use instrument for measuring many types of thin-film coatings as shown in

figure 4-10

(a) Front Panel (b) Back Panel

Fig 4-10 Inficon SQM-160

83

Table 4-1 shows the technical specifications for this equipment

Number of sensors 2 Standard 4 additional optional

Sensor Frequency Range 40 MHz ~ 60 MHz

Reference Frequency Accuracy 002

Thickness Display Resolution 1 Aring

Thickness Resolution 015 Aring (Std) 0037 Aring (Hi Res)

Density of Stored Films 05-9999 gmcc

Tooling 10-399

Z-Factor 010-1000

Final Thickness 0000-9999k Aring

Measurement Period 15 to 2 sec

Simulation Mode Yes

Frequency Mode Yes

Rate Resolution 011 Arings

Dual Crystal Yes

Etch Mode Yes

Crystal Tooling 10-399

Crystal Fail Min Max 40 to 60 MHz 41 to 61 MHz

Power 100-120 200-240~plusmn10 nominal 20W

Operation Environment 0degC ~ 50degC

0 ~ 80 RH non-condensing

0 ~ 2000 meters

Class 1 Equipment

Pollution Degree 2

Rack Dimensions 885mm x 2127mm x 1969mm

Weight 27 kg

Table 4-1 Inficon SQM-160 RateThickness Monitor Specs

84

To the SQM-160 we need to connect an Oscillator We use the Sigma Instruments Remote Oscillator

Ser No 2 268 as shown in figure 4-11

Fig 4-11 Sigma Instruments Remote Oscillator

The connections diagram is shown in figure 4-12

Fig 4-12 SQM-160 Connections Diagram

85

423 Turbo Pump

For our experiments we used the Pfeiffer TCP 015 Electronic Drive Unit shown below in figure 4-13

Table 4-2 shows the technical specifications for this equipment

(a) Front Panel (b) Back Panel

Fig 4-13 Pfeiffer TCP 015 Electronic Drive

Connection Voltage (100V) 90-112

Mains Frequency 5060 Hz

Start-up Current 22 A

Nominal Frequency 1500 Hz

Rotation Speed 10V = 1500Hz plusmn2

Analog Output Current 10 V = 25 A plusmn 5

Rotation Speed Switchpoint 750 Hz

Works Setting 8 min

Permissible Ambient Temperature 0degC ~ 40degC

Dimensions Front Panel 1285mm x 1063mm

Insertion Length 227mm

Weight 27 Kg

Table 4-2 Pfeiffer TCP 015 Electronic Drive Specs

86

The connections diagram is shown in figure 4-14

Fig 4-14Connections Diagram for Pfeiffer TCP 015

To measure the pressure inside the chamber we use the Granville Phillips 375 Convectron Vacuum

Pressure Controller shown in figure 4-15

(a) Front Panel (b) Back Panel

Fig 4-15 Granville Phillips 375 Convectron

87

Its dimensions are shown in figure 4-16

Fig 4-16 Dimensions of Convectron

Table 4-3 shows the technical specifications for this equipment

Table 4-3 Granville Phillips 375 Convectron Vacuum Pressure Controller Specs

88

424 Multimeter

For our experiment we used the Keithley 2000 Digital Multimeter as shown in figure 4-17

(a) Front Panel (b) Back Panel

Fig 4-17 Keithley Model 2000 6-12-Digit Digital Multimeter

Its technical specifications are shown in table 4-4

Table 4-4 Keithley Model 2000 6-12-Digit Digital Multimeter Specs

89

43 Experiment Procedure

1 Connecting together the equipment and the chamber

(1) We first connect the resonator to the thickness monitor and connect the other side to the

chamber

(2) We now connect the flexible tubes to the turbo pump on one side and to the chamber on the

other

(3) We need to check that tubes are tightly connected to avoid any leaks in the vacuum pumping

process which will not allow us to get to our goal of Torr As shown in figure 4-18

(4) Connect the convectron to the system as shown in figure 4-19

Fig 4-18 checking for leaks using alcohol

Fig 4-19 Convectron attached to System

90

(5) Attach the clamps of the Multimeter to the bottom of the chamber as shown in figure 4-20

(6) Place the Quartz crystal in place

(7) Close tight vacuum chamber

(8) Connect all electrical appliances to power source

Fig 4-20 Multimeter Connections

2 Starting up the System

(1) We turn on all the devices as such Check all systems are ready to function Reset all values

that might be left over from previous tests

(2) Start the thickness monitor and set all values for this experiment In our case we got to testing

the system but not actual coating So we used the simulation mode of the thickness monitor as

shown in figure 4-21

Fig 4-21 Simulation Mode

91

(3) Start the turbo pump Make sure the lid on the vacuum chamber is tightly closed

(4) Start convectron and record initial pressure

(5) Start Multimeter and record initial current

3 Coating Process

(1) If we have the deposition material inside the filament boat the power source for the high

current must be started as well

(2) Record all initial values for thickness current pressure

(3) For an ideal experiment we need a thickness of around 101 nm a pressure of Torr and

a current of 300 A

44 Results

From previous experiments we have shown that we can turn a LED into a laser by means of AR

Coating In figure 4-22 shown below we can compare the actual results of a Diode before and after AR

coating From the blue line we can see that when the diode is at a current of 15mA its light will change

from LED to laser and if we look at the red line its critical current is around 30 to 35 mA

Fig 4-22 AR Coating Comparison for Laser Diodes

This means that the light emitted is not as strong as if the diode had been coated because inside the

chamber there must be some excitation first so the reflectivity of both sides inside the diode must be high

So because of the coating in one of the sides we have opened a door and let the light come out so the

critical current is risen as such and will be higher value than that of before the coating

92

In the following figures we can see the difference between before and after coating in a material The

thickness is around 1016 nm for this material

Fig 4-23 Before Coating

Fig 4-24 After Coating

93

Chapter 5 CONCLUSIONS AND RECOMMENDATIONS

51 Conclusions

For the first part of this independent study taking into consideration the data that came out of our

research and that sent by the provider we can say

1 SUM 23 after heat treatment will unexpectedly develop cracking in the middle of the tensile

testing process and suddenly break

2 Itrsquos possible that in the process of heat treatment to the SUM 23 material the treatment was not

uniform and this will create a pre-loaded moment force on one side that pushes on the other side

of the specimen resulting in material deformation

3 In the process of attaching the strain gauges to the materials it is very easy to make errors due to

poor adhesion or sudden removal in the tensile testing process

For our second part of the independent study the following can be made

1 At the beginning of this independent study we had no idea what Bose-Einstein Condensate was

or what was its purpose After much literature we finally comprehended the basic principles to

put into practice for our research

2 Our systemrsquos basic working principles and equipmentrsquos complexity are a little difficult to grasp

but hopefully we were able to understand enough of it

3 Theoretically from relation between the power and current we can know the advantages and

disadvantages of AR Coating

4 We were able to assemble the system and run test on its functions Even though we were able to

do this there is still much more work left to do with this system

52 Recommendations

For the Tensile Testing the following can be said

1 Ask the provider to check on the process of heat treatment on the SUM 23 material and give

them the information we have gathered through our test so they can correct for the mechanical

properties found if any change is needed

2 To avoid the problem of the inaccuracy of the poor adhesion of strain gauges we can attach

multiple strain gauges to the same one specimen so as to correlate data and improve our results

For the AR Coating the following can be said

1 We need to make sure that there are no physical defects on the main body of the chamber so as to

achieve maximum efficiency in the vacuum process If there was then the vacuum will arrive to

certain point and then start to decrease

2 It would be preferable to add some sort of visual aid that will allow the user to check the inside of

the chamber without actually opening it This will help us determine at what times we should

manipulate the current to better evaporate the substrate

94

REFERENCES

[1] A L Window Strain Gauge Technology Elsevier Applied Science London and New York 2nd

Edition 1992

[2] CC Perry and HR Lissner Strain Gauge Primer McGraw-Hill Book Co Inc New York 1955

[3] James W Dally William F Riley McGraw-Hill 1978

[4] University of Colorado Boulder BEC - What is it and where did the idea come from

httpwwwcoloradoeduphysics2000becwhat_is_ithtml

[5] Ultraslow Light amp Bose-Einstein Condensates Two-way Control with Coherent Light amp Atom

Fields Harvard Hau Lab Dr Lene Vestergaard Hau Optics amp Photonics News 16 1995

[6] The Art of Taming Light Ultra-slow and Stopped Light Harvard Hau Lab Dr Lene

Vestergaard Hau Europhysics News 2004

[7] Nonlinear Optics Shocking Superfluids Harvard Hau Lab Dr Lene Vestergaard Hau Nature

Physics 2007

[8] Model P3 Strain Indicator and Recorder Instruction Manual Vishay Micro-Measurements 2005

[9] Granville-Phillips Series 375 Convectron Vacuum Gauge Controller Instruction Manual Brooks

Automation 2008

[10] Effect of Film Thickness on the Validity of the Sauerbrey Equation for Hydrated Polyelectrolyte

Films Vogt Lin Wu White 2004

[11] Quartz Crystal Microbalance Study of DNA Immobilization and Hybridization for DNA Sensor

Development Chang Zhao 2008

[12] Installation of Strain Gages with SR-4 PrecoatAdhesive Vishay Micro-Measurements 2005

[13] Strain Gauge Measurement ndash A Tutorial National Instruments 1998

[14] Correlation between Vickers Hardness Number and Yield Stress of Cold-Formed Products

Yavuz Tekkaya

[15] httpsenwikipediaorg

Page 3: PC Hinge Materials Testing and AR Laser Diode Coating

3

special properties such as Youngrsquos modulus Poisson ratio yield strength tensile strength and

so on The experimental results may be entered into the subsequent finite element analysis

software the objective is to enter the materialrsquos real parameters to make the structural analysis

simulation more realistic

The 2nd

focus of this independent study is to help in the further research of the

Bose-Einstein condensate This is a state of matter of a dilute gas weakly interacting bosons

(subatomic particles that obey the Bose-Einstein statistics) confined in an external potential and

cooled down to temperatures very near absolute zero (0 K or -27315deg C) Under these conditions

a large number of bosons occupy the lowest quantum state of the external potential at which

point quantum effects become apparent at macroscopic scale This state of matter was predicted

by Satyendra Nath Bose and Albert Einstein in 1924~1925 Then 70 years later the 1st gaseous

condensate was produced by Eric Cornell and Carl Wieman in 1995 at the University of

Colorado (Boulder) NIST-JILA lab and because of this along with Wolfgang Ketterle of MIT

they received the 2001 Nobel Prize in Physics

We designed and have constructed a vacuum chamber where Anti Reflecting Coating will be

applied to laser diodes in order to reduce the reflectivity of the laser diodersquos surface to make

effective the injection lock This creates a desired wavelength of light inside a laserrsquos pumping

medium and may reduce surface reflection coefficient to less than 01 We expect to obtain

certain desired working properties after this process which will allow us to continue our project

We hope that through our research we can find significant applications to this theory

4

ACKNOWLEDGEMENT

First and foremost I would like to thank God I would never have done this study without the

faith I have in you the Almighty

I would like to thank my parents Gloria Iveth Sanchez and Juan Carlos Bonilla my sisters

Joanna Iveth Bonilla Karla Ines Bonilla and Kelly Gabriela Bonilla and my entire family for

their love support patience and understanding during my 5 years of studying abroad

I owe my deepest gratitude to my advisor Professor Ho-Chiao Chuang PhD for letting me

carry out this study Without his support and comprehension this study would have never been

carried out

Special thanks to Institute of Atomic and Molecular Sciences Academia Sinica Dr

Ming-Shien Chang for without him I would not be able to understand and put into practice

some of the principles presented in this thesis

I am indebted to many friends and classmates for the invaluable support during my studies in

this country and in this University

A special mention to my beloved friends Christian Reyes Francisco Garcia Jose Pagoada

and Olvin Castillo to my classmates 姚呈忠 王煜璨 林炯宇 for helping me during my tough

times my senior 廖梃君 and my junior 石中鈺 for thanks to them I was able to work and

present results during the course of this research and everyone else involved at the Department

of Mechanical Engineering at National Taipei University of Technology

5

TABLE OF CONTENTS

ABSTRACThelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 2

ACKNOWLEDGEMENThelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 4

TABLE OF CONTENTShelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 5

LIST OF TABLEShelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 7

LIST OF FIGUREShelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 8

CHAPTER 1 Introductionhelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 10

11 Motivation and Backgroundhelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 10

12 Research Objectivehelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 11

13 Methodologyhelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 13

14 Organization of the Thesishelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 13

CHAPTER 2 Basic Principleshelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 14

21 Tensile Testinghelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 14

211 Youngrsquos Modulushelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 14

212 Yield Strength and Yield Pointhelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 15

213 Ultimate Tensile Strength and Breaking Strengthhelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 16

214 Poissonrsquos Ratiohelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 16

215 Strain Gauge Basic Principleshelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 16

22 Hardness Test Basic Principleshelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 18

221 Brinell Scale BHNhelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 18

222 Rockwell Scale HRhelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 19

223Vickers Hardness Test HVhelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 21

23 AR Coatinghelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 22

231 Bose-Einstein Condensatehelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 22

232 AR Coating Basic Principleshelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 25

233 Laser Diode Basic Principleshelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 28

234 Quartz Microbalance Systemhelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 29

235 Vacuum Chamber Systemhelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 38

CHAPTER 3 Tensile Testing in depthhelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 41

31 Experimentrsquos Purpose and Principleshelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 41

32 Experimentrsquos Equipmenthelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 41

321 Universal Testing Machinehelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 41

322 Strain Measurement Equipmenthelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 43

6

323 Strain Gaugehelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 45

324 Specimen Measurementshelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 47

33 Experiment Procedurehelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 47

34 Resultshelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 54

341 SUM 23helliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 55

342 SUM 43helliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 67

CHAPTER 4 AR Coating in depthhelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 77

41 Experimentrsquos Purpose and Principleshelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 77

42 Experimentrsquos Equipmenthelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 78

421 Vacuum Chamberhelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 78

422 Quartz Microbalancehelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 82

423 Turbo Pumphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 85

423 Multimeterhelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 88

43 Experiment Procedurehelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 89

44 Resultshelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 91

CHAPTER 5 Conclusions and Recommendationshelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 93

51 Conclusionshelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 93

52 Recommendationshelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 93

REFERENCEShelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 94

7

LIST OF TABLES

Table 2-1 Rockwell Hardness Test Scalehelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 20

Table 2-2 Z-Ratios for Different Materialshelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 33

Table 2-3 Classifications of Vacuumhelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 39

Table 3-1 Chun Yen Testing Machine Specshelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 42

Table 3-2 Vishay Micro-Measurements Model P3 Strain Indicator and Recorder Specshelliphelliphelliphelliphelliphellip 44

Table 3-3 Specifications for Round Barhelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 47

Table 3-4 Specifications for Strain Gaugehelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 48

Table 3-5 Mechanical Properties of SUM 23 Untreatedhelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 55

Table 3-6 Mechanical Properties of SUM 23 Nickelhelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 58

Table 3-7 Mechanical Properties of SUM23 Black Surface Materialhelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 63

Table 3-8 Mechanical Properties of SUM 43 Untreatedhelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 67

Table 3-9 Mechanical Properties of SUM 43 Nickelhelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 70

Table 3-10 Mechanical Properties of SUM 43 Black Surface Materialhelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 73

Table 4-1 Inficon SQM-160 RateThickness Monitor Specshelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 83

Table 4-2 Pfeiffer TCP 015 Electronic Drive Specshelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 85

Table 4-3 Granville Phillips 375 Convectron Vacuum Pressure Controller Specshelliphelliphelliphelliphelliphelliphelliphelliphellip 87

Table 4-4 Keithley Model 2000 6-12-Digit Digital Multimeter Specshelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 88

8

LIST OF FIGURES

Fig 1-1 Notebook Computer Hingehelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 11

Fig 1-2 Basic Structure of Laserhelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 11

Fig 1-3 Comparison between LED and Laser Diodehelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 12

Fig 1-4 External Cavity Designhelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 12

Fig 2-1 Stress-Strain Curvehelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 14

Fig 2-2 Stress-Strain Curve Comparison on Metalshelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 15

Fig 2-3 Basic Structure of Strain Gaugehelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 17

Fig 2-4 Strain Gauge Attached to Wheatstone Bridgehelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 18

Fig 2-5 Brinell Indentationhelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 18

Fig 2-6 Brinell Hardness Testerhelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 18

Fig 2-7 Rockwell Indentationhelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 19

Fig 2-8 Rockwell Hardness Testerhelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 19

Fig 2-9 Vickers Indentationhelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 22

Fig 2-10 Vickers Hardness Testerhelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 22

Fig 2-11 Bose-Einstein Condensate at different scaleshelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 23

Fig 2-12 Super Conductorhelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 24

Fig 2-13 Simple Model for Light in Glass Mediumhelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 25

Fig 2-14 Simple Model for Light in Glass Medium after AR Coatinghelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 26

Fig 2-15 Light Passing through AR Coating and Glasshelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 27

Fig 2-16 Lens without and with AR Coatinghelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 27

Fig 2-17 Laser Diodehelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 28

Fig 2-18 Tunable Laser Basic Configurationhelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 28

Fig 2-19 Light Spectrumhelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 29

Fig 2-20 Front and Back Panel of SQM-160helliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 29

Fig 2-21 QCM Crystalshelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 31

Fig 2-22 SQM-160 Oscillatorhelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 31

Fig 2-23 Oscillator Circuithelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 32

Fig 2-24 Vacuum Evaporation Systemhelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 39

Fig 2-25 Turbo Pumphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 39

Fig 2-26 Control and Measurement Equipmenthelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 40

Fig 2-27 Complete Systemhelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 40

Fig 3-1 Universal Testing Machinehelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 41

Fig 3-2 Diagram for System Connectionshelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 42

Fig 3-3 Input Connections for Strain Gaugehelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 43

Fig 3-4 Vishay Micro-Measurements Model P3 Strain Indicator and Recorderhelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 43

Fig 3-5 Inner Connectionshelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 45

Fig 3-6 Tensile Specimenhelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 47

Fig 3-7 Actual Tensile Specimenhelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip47

Fig 3-8 Other Materials Usedhelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 48

Fig 3-9 Specimen-Strain Gauge Processhelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 49

Fig 3-10 Specimen-Tensile Testing Processhelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 53

9

Fig 3-11 SUM 23 Untreated Materialhelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 55

Fig 3-12 Stress-Strain Diagrams for 7 and 10 Round Barhelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 56

Fig 3-13 Cut-Off Area of 7 and 10 Round Barhelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 57

Fig 3-14 SUM 23 Nickel Materialhelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 58

Fig 3-15 Stress-Strain Diagrams for 1 2 3 and 4 Round Barhelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip60

Fig 3-16 Cut-Off Area of 1 2 3 and 4 Round Barhelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 62

Fig 3-17 SUM 23 Black Surface Materialhelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 63

Fig 3-18 Stress-Strain Diagrams for 1 2 and 3 Round Barhelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 65

Fig 3-19 Cut-Off Area of 1 2 and 3 Round Barhelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 66

Fig 3-20 SUM 43 Untreated Materialhelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip67

Fig 3-21 Stress-Strain Diagrams for 1 and 5 Round Barhelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 68

Fig 3-22 Cut-Off Area of 1 and 5 Round Barhelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 69

Fig 3-23 SUM 43 Nickel Materialhelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 70

Fig 3-24 Stress-Strain Diagrams for 4 and 5 Round Barhelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 71

Fig 3-25 Cut-Off Area of 4 and 5 Round Barhelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 72

Fig 3-26 SUM 43 Black Surface Materialhelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 73

Fig 3-27 Stress-Strain Diagrams for 3 and 5 Round Barhelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 74

Fig 3-28 Cut-Off Area of 3 and 5 Round Barhelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 75

Fig 4-1 BEC Apparatushelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 77

Fig 4-2 Vacuum Chamber Main Bodyhelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 78

Fig 4-3 Thermocouplehelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip79

Fig 4-4 Filament Boat Clamp Designhelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 79

Fig 4-5 Cover Assemblyhelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 80

Fig 4-6 Upper Cover Inner Assemblyhelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 80

Fig 4-7 Diagram of Upper Cover Connectionshelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 81

Fig 4-8 Feed Through Diagramhelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 81

Fig 4-9 Fully Assembled Chamberhelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 82

Fig 4-10 Inficon SQM-160helliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 82

Fig 4-11 Sigma Instruments Remote Oscillatorhelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 84

Fig 4-12 SQM-160 Connections Diagramhelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 84

Fig 4-13 Pfeiffer TCP 015 Electronic Drivehelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 85

Fig 4-14 Connections Diagram for Pfeiffer TCP 015helliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 86

Fig 4-15 Granville Phillips 375 Convectronhelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 86

Fig 4-16 Dimensions of Convectronhelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 87

Fig 4-17 Keithley Model 2000 6-12-Digit Digital Multimeterhelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 88

Fig 4-18 Checking for Leaks Using Alcoholhelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 89

Fig 4-19 Convectron Attached to Systemhelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 89

Fig 4-20 Multimeter Connectionshelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 90

Fig 4-21 Simulation Modehelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 90

Fig 4-22 AR Coating Comparison for Laser Diodeshelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 91

Fig 4-23 Before AR Coatinghelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 92

Fig 4-24 After AR Coatinghelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 92

10

Chapter 1 INTRODUCTION

11 Motivation and Background

In response that new generation computers are gradually reducing their size the diameter of

the structures of the hinges used by NB computers must also follow but the hinge strength may

also become smaller due to the reduction of diameter and result in the phenomenon of

insufficient strength In addition the disk-type spring that is source of the torque may also be

insufficient due to the narrowing of the structure Therefore it is necessary to direct a structural

analysis of the hinge for the existing laptops so that we can identify the stress concentration

point The stress concentration point is usually the point where material damage behavior is

encountered the easiest and if we can find the point where breaking occurs most often we can

improve the design of the existing structure to enhance the strength of the hinge structure

Second the structure of the hinge is too complicated the traditional mechanics of materials

analysis methods and formulas are no longer suitable for analysis of a wide arrange of hinge

design In recent years finite element analysis methods have been widely applied in various

fields such as electronics machinery aviation and so on

Therefore to meet the need of the industry and with the purpose of reducing design time

how to design a notebook computer hinge without compromising mechanical stability and

materialrsquos hardness which will operate equally under equal conditions In other words be able to

meet the needs of the size decreasing NB computers market as the needs for this kind of

accessories will increase in the near future If we take into consideration the traditional ways of

design we seek to reduce the costs of use of machinery and molding by applying Finite Element

Analysis methods to our study and also increase the flexibility of designing methods

The second project was brought in by Prof Chuang and it is to help in the further research of

the Bose-Einstein condensate This is a state of matter of a dilute gas weakly interacting bosons

(subatomic particles that obey the Bose-Einstein statistics) confined in an external potential and

cooled down to temperatures very near absolute zero (0 K or -27315deg C) Under these conditions

a large number of bosons occupy the lowest quantum state of the external potential at which

point quantum effects become apparent at macroscopic scale This state of matter was predicted

by Satyendra Nath Bose and Albert Einstein in 1924~1925 Then 70 years later the 1st gaseous

condensate was produced by Eric Cornell and Carl Wieman in 1995 at the University of

Colorado (Boulder) NIST-JILA lab and because of this along with Wolfgang Ketterle of MIT

they received the 2001 Nobel Prize in Physics

11

We wish to investigate the properties of Anti Reflecting Coating on laser diodes Hopefully

we will be able to achieve the desired effect of reducing the surface reflection coefficient and

find applications for it

12 Research Objective

We wish to analyze the normal composition of the notebook computerrsquos hinge at which

point in the assembly is clearly the weakest and at this time in the assembly the strength and

durability are influenced The main point is to see if we can affect the normal operation and work

life

The objective of this thesis is to present the results of the material properties under tensile

testing find the mechanical properties and after using finite element analysis determine what

material is the best for our purposes

Fig 1-1 Notebook Computer Hinge

For our second research we wish to produce and analyze laser diodes with anti-reflective

coating and test its properties and applications

When semi-conductor laser has been submitted to current it will produce resonance inside it

and light will be stimulated to come out Please refer to figure 1-2 for the basic structure of a

laser

Fig 1-2 Basic Structure of a Laser

1 Gain Medium

2 Laser Pumping Energy

3 High Reflector

4 Output Coupler

5 Laser Beam

12

But when the laser diode generates light but the laser diode canrsquot produce light on itself it

must wait for the current to be higher than certain value which is called the critical current Until

the light goes over this threshold then it is considered laser light if not it is just considered as a

common LED light source Please refer to figure 1-3

Fig 1-3 Comparison between LED and Laser Diode

As we can see from figure 1-3 all of the light that goes over the critical current is laser light

and so the external cavity semi-conductor laser that we built needs Anti-Reflective Coating

because the method we want to use needs an external cavity laser that has been covered with AR

Coating and a Diffraction Grating We use this configuration first by shooting the laser to the

grating and this will be shot back to the laser creating the external resonance cavity which is

shown in figure 1-4

Fig 1-4 External Cavity Design

13

Two configurations are shown the Littrow Configuration and the Littman-Metcalf

Configuration The Littrow configuration contains a collimating lens and a diffraction grating as

the end mirror The first order diffracted beam provides optical feedback to the laser diode which

has AR Coating The emission wavelength can be turned by rotating the diffraction grating A

disadvantage is that it also changes the direction of the output beam

In the Littman-Metcalf configuration the grating orientation is fixed and an additional mirror

is used to reflect the first order beam back to the laser diode The wavelength can be turned by

rotating that mirror This configuration offers a fixed direction of the output beam and also tends

to exhibit smaller line width as the wavelength selectivity is stronger A disadvantage is that

zero order reflection of the beam reflected by the tuning mirror is lost so that the output power is

less than that of a Littrow laser

13 Methodology

The aim of this research is to find the mechanical properties of materials after being

subjected to tensile testing through finite element analysis observations and determine what

material is best for our purposes taking into consideration the strength and durability of the

material among other properties to find use and applications for the AR coated laser diodes to

further improve the grasp of the Bose-Einstein condensation working principles

14 Organization of the Thesis

The research paper includes five chapters

1 Chapter 1 explains the motivation background objective and methodology of this study

2 Chapter 2 explains the working principles and basic knowledge needed to understand this

study

3 Chapter 3 explains the tensile testing in detail steps methods and results

4 Chapter 4 explains the AR coating in detail steps methods and results

5 Chapter 5 is the conclusions taken from the results shown in chapter 3 and 4 and

recommendations done after arranging and critical thinking

14

Chapter 2 BASICS THEORIES

21 Tensile Testing

After a specimen is tested with the use of tensile testing we can get the Stress-Strain Curve using the

relation between tension and displacement Typical curves are shown in Fig 2-1

(a) Ductile materials (b) Brittle materials

Fig 2-1 Stress-Strain Curve

The curve is unique for each material and is found by recording the amount of deformation at distinct

intervals of tensile or compressive loads Thanks to the use of the Stress-Strain curve we can get very

useful information such as

211 Youngrsquos Modulus (E)

As shown in Fig 2-1 as long as the external load is not greater than the Proportional Limit the Stress

(σ) and Strain (ε) remain as a linear relation fulfilling Hookersquos Law

σ = Eε

The slope is the constant factor the inverse of the modulus of elasticity E also called Youngrsquos

modulus When the external load goes over the proportional limit the stress-strain relationship doesnrsquot

follow the linear relation anymore but the deformation remains flexible When the load is released the

deformation is completely eliminated and the specimen goes back to its original state This is called

15

Elastic Deformation When the external load goes over the Elastic limit only then does the specimen

presents Plastic Deformation This type of deformation which is irreversible even when the load is

removed comes after the material does under elastic deformation so this means the object will first come

part way to its original shape Common metals and ceramics have roughly the same elastic limits

212 Yield Strength and Yield Point

Some materials display very evident yield phenomena while some materials donrsquot as shown in Fig

2-2 After we exceed the elastic limit if we continue to exert load when we arrive to a certain value

which differs under different materials and external conditions there is sudden decrease in stress and this

is called the Yield Strength and can be defined as the stress at which a material begins to deform

plastically using the equation

σyield =

Where P is the tension force and Ao is the original cut-off area

The stress remain at a certain value after the decrease but the strain increases this phenomena can be

easily appreciated when studying the behavior of common Carbon Steel Fig2-2 (a) but most metals (like

Aluminum Copper or High Steel Carbon) donrsquot display this kind of behavior as shown in Fig 2-2 (b)

Arriving to this point is very difficult and the most commonly used method for this is to add a 02 or

0002 offset yield strength to the curve This point is held constant on the strain axis of the curve and

from the 0002 position we draw a straight line parallel to the linear relationship line the point at where

this line and the stress-strain curve intercept is the point we take as the 02 offset yield strength

(a)Evident (b) Non-evident

Fig2-2 Stress-Strain Curve Comparison on Metals

16

213 Ultimate Tensile Strength and Breaking Strength

After materials undergo yield they keep lending strength and hardening phenomena occurs (work

hardening) on the material and the external load increases When it has reached the highest point this is

called the Ultimate Tensile Strength (UTS) as shown in Fig2-1 The UTS is defined as

σUTS =

Where Pmax is the load at the materialrsquos ultimate tensile strength point and Ao is the original cut-off

area For brittle materials the ultimate tensile strength is the most important mechanical property for

ductile materials the ultimate tensile strength is not commonly used for industrial and designing purposes

because upon arriving to this value the material already has forgone great plastic deformation After the

specimen goes through UTS there will be necking phenomena which is a mode of tensile deformation

where relatively large amounts of strain localize disproportionately in a small region of the material It

results from instability during tensile deformation when a materialrsquos cross-sectional area decreases by a

greater proportion than the material strain hardens The specimen continues to elongate until it finally

breaks and the load at this point is called Breaking Strength The breaking strength is defined as the

greatest stress in tension that a material is capable of withstanding without rupture

Where Pf is the load at the materialrsquos breaking strength point and Ao is the original cut-off area

214 Poissonrsquos Ratio (ν)

For elastic deformation when materials are compressed in one direction they tend to expand in the

other two directions perpendicular to the direction of compression This is called the Poissonrsquos Effect

The Poison Ratio is a measure of the Poissonrsquos effect It is the ratio of the fraction of expansion divided

by the fraction of compression for small values of these changes

ν=-

215 Strain Gauge Basic Principles

The strain gauge is a device used to measure the strain of an object Itrsquos an elongated metal resistor

which is attached to the specimen being measured and when the specimen is under strain and starts to

deform the strain gauge will have a change in the resistance With the change in value we can calculate

the elementrsquos strain or elastic modulus and the Poissonrsquos ratio

It takes advantage of the physical property of electrical conductance and its dependence on the

conductorrsquos geometry When the electrical conductor (the specimen being tested) is stretched within the

limits of elasticity such that it does not break or deform plastically it will become narrower and longer

17

which increases the electrical resistance through-out From the measured resistance of the strain gauge

the amount of stress may be inferred by using the relations

R=

Where R is the original resistance value is the electrical resistivity lo is the original length of the

conductor and Ao is the original cross sectional area of the conductor If after the application of tension

the change in length is Δl let the length of the specimen be l = l + Δlo and the tension is the same

through-out So

And the resistance is

The Gauge Factor is the ratio of relative change in electrical resistance to the mechanical strain in

other words it is the relative change in length It is defined as

The strain gauge was invented in 1938 by Edward E Simmons and Arthur C Ruge and the most

common type consists of an insulating flexible backing which supports a metallic foil usually made of a

brass-nickel alloy It is attached to the specimen by a suitable adhesive As the object is deformed the foil

also deforms and this causes the electrical resistance to change Then this is usually measured using a

Wheatstone bridge shown below and is related to the strain by the Gauge Factor

Fig2-3 Basic Structure of Strain Gauge

18

Fig 2-4 Strain gauge attached to Wheatstone bridge

22 Hardness Testing Basic Principles

221 Brinell Scale BHN

The Brinell Scale characterizes the indentation hardness of materials through the scale of penetration

of an indenter loaded on a material specimen The typical test uses a 10mm diameter steel ball as indenter

(usually of value equal to BHN450) with a 29kN force For softer materials smaller force is used The

indentation is measured and BHN is calculated using the relation

BHN =

radic

Where F is the applied force usually within the range of 100 250 500 750 1000 1500 2000 2500

and 3000 kgf D is the diameter of indenter usually within the range of 5mm or 10mm plusmn0005 margin

and d is the diameter of indentation usually around 2mm Its units are of Kgmmsup2 but are not normally

written

First proposed by Swedish engineer Johan August Brinell in 1900 it was the first widely used and

standardized hardness test in engineering and metallurgy although the large size of indentation and

possible damage to specimen limits its usefulness

Fig 2-5 Brinell Indentation Fig2-6 Brinell Hardness Tester

19

222 Rockwell Scale HR

The Rockwell scale is a hardness scale based on the indentation hardness of a material The Rockwell

test determines the hardness by measuring the depth of penetration of an indenter under a large load

compared to the penetration made by a preload The indenter is forced into the specimen under a

preliminary load When equilibrium is reached a measuring device follows the movements of the

indenter and responds to changes in depth of penetration of the indenter While the preload is still being

applied additional major load is applied resulting in increased penetration When equilibrium is reached

again the major load is removed but the preload is maintained Removing the major load allows partial

recovery and reduces the depth of penetration The permanent increase in depth of penetration resulting

from the application and removal of the major load is used to calculate the Rockwell number using the

relation

HR = E ndash e

Where E is a constant depending on the form of the indenter 100 units for diamond indenter and 130

units for steel ball indenter e is the permanent increase in depth of penetration due to the major load

measured in units of 0002mm

Fig 2-7 Rockwell Indentation

When testing materials indentation hardness is related linearly to the tensile strength The important

relation permits economically important nondestructive testing of bulk metal deliveries with lightweight

equipment like the Rockwell tester shown below in figure 2-7

Fig 2-8 Rockwell Hardness Tester

20

There are different scales denoted by a single letter that use different loads or different indenters

The result is a dimensionless number denoted as HR X where X will be the letter denoting the scale as

shown below in table 2-1

Table 2-1 Rockwell Hardness Test Scale

Differential depth hardness measurement was first conceived in 1908 by Viennese professor Paul

Ludwik It eliminated the errors associated with the mechanical imperfections of the system such as

backlash and surface imperfections in the specimen Rockwell testing has an advantage over Brinell

testing because the latter was slow itrsquos not useful on fully hardened steel and left too large an impression

to be considered nondestructive

The tester was co-invented by Hugh M Rockwell and Stanley P Rockwell The requirement for this

tester was to quickly determine the effects of heat treatment on steel bearing races

21

223 Vickers Hardness Test HV

This is a type of microindentation hardness test where a diamond indenter of specific geometry is

impressed into the surface of the test specimen using a known applied force ranging from 10 to 1000

grams This type of tests usually has forces of 2N and produce indentations of about 50μm They can be

used to observe changes in hardness on the microscopic scale It is difficult to standardize the

microhardness measurements because it has been found that the microhardness of almost any material is

higher than its macrohardness The values also vary with load and work-hardening effects of materials

The Vickers test is often easier to use than other hardness tests because the required calculations are

independent of the size of the indenter and the indenter can be used for all materials It can be used for all

metals and has one of the widest scales among hardness tests The unit of the Vickers test is denoted as

HV and can be converted to units of Pascal (Pa) but it is not a measurement of pressure The hardness

number is determined by the load over the surface area of the indentation and not the area normal to the

force

A square-based pyramid shaped diamond is use as the indenter It has been established that the ideal

size of a Brinell impression was 38 of the ball diameter As two tangents to the circle at the ends of a

chord 3d8 long intersect at 136plusmn05deg it was decided to use this as the angle of the indenter giving an

angle to the horizontal plane of 22deg on each side The HV number is determined by the ratio FA where F

is the force applied to the diamond in kgf and A is the surface area of the resulting indentation in mmsup2 A

can be determined by the relation

A =

Where A is the surface area of indentation and d is the average length diagonal left by the indenter

This can be approximated as

A =

Then the Vickers Number is

HV =

=

Vickers hardness number is reported as xxxHVyy or xxxHVyyzz (if duration of applied force differs

from 10s to 15s) where xxx are replaced by the hardness number yy is the load in kg and zz indicates

loading time The values are generally independent of test force

The test was developed in 1921 by Robert L Smith and George E Sandland at Vickers Ltd as an

alternative to Brinell method to measure the hardness of materials

22

Fig 2-9 Vickers Indentation Fig 2-10 Vickers Hardness Tester

23 AR Coating

231 Bose-Einstein Condensate

The Bose-Einstein Condensate or BEC is a state of matter of a dilute gas of bosons cooled to

temperatures very near absolute zero around 0K or -27315degC Under such conditions a large fraction of

the bosons occupy the lowest quantum state where the quantum effects become apparent on a

macroscopic scale This gave birth to the Bose-Einstein Statistics which are the rules that govern the

behavior at this state It is one of the two possible ways in which a collection of indistinguishable particles

may occupy a set of available discrete energy states The aggregation of particles in the same state

accounts for the cohesive streaming of laser light and the frictionless creeping of superfluid helium (an

application discussed later) Bose and Einstein recognized that a collection of identical and

indistinguishable particles can be distributed this way This theory applies only to those particles not

limited to single occupancy of the same state particles that do not obey the Pauli Exclusion Principle

restrictions Such particles are the Bosons named after the statistics that correctly describe their behavior

This phenomenon was first predicted by Satyendra Nath Bose around 1924 when he considered how

groups of photons behave He then asked Albert Einstein for help publishing his discoveries to which

Einstein agreed and gave follow up supporting these findings The resulting efforts became the concept of

a Bose gas governed by the Bose-Einstein Statistics described above Einstein demonstrated that cooling

bosonic atoms to a very low temperature would cause them to condense into the lowest accessible

quantum state resulting in a new form of matter

The first gaseous condensate we produced by Eric Cornell and Carl Wieman at the University of

Colorado at Boulder NIST ndash JILA lab sung a gas of rubidium atoms cooled to 170 nK which earned

them the 2001 Nobel Prize in physics together with Wolfgang Ketterle from MIT The transition to BEC

occurs below a critical temperature which for a uniform three dimensional gas consisting of

non-interacting particles with no apparent internal degrees of freedom is given by

23

Tc =

(

)

asymp 33125

Where Tc is the critical temperature n is the particle density m is the mass per boson h is the

reduced Planck constant k is the Boltzmann constant and ζ is the Riemann zeta function

There are two classes of elementary particles defined by whether their quantum spin is a nonnegative

integer or an odd half integer A Bose-Einstein Condensate is shown below in figure 2-11

Fig 2-11 Bose Einstein Condensate at different scales

Bosons are the particles whose quantum spin is a nonnegative integer (s = 0 1 2 etc) Examples of

bosons include fundamental particles (Higgs Boson Photons W and Z Bosons Gluons Gravitons etc)

composite particles (Mesons Hadrons Nuclei and Atoms of Carbon-12 and Helium-4) and

quasi-particles Bosons are considered force carrier particles The Bosons differ from Fermions in that

there is no limit to the number that can occupy the same quantum state This is called the Pauli Exclusion

Principle

The Pauli Exclusion Principle says that no two identical fermions may occupy the same quantum state

simultaneously in other words this means that the total wave function for two identical fermions is

anti-symmetric with respect to exchange of the particles This means that no two electrons in a single

atom can have the same four quantum numbers

Fermion is any particle characterized by Fermi-Dirac Statistics and follows the Pauli Exclusion

Principle described above Quarks Leptons and composite particles (Hadrons Nuclei and Atoms of

Carbon-13 and Helium-3) made of an odd number of these are considered Fermions It can be an

elementary particle such as the electron or a composite particle such as the protons Following the Pauli

24

Exclusion Principle only one fermion can occupy a particular quantum state at any given time If multiple

fermions have the same spatial probability distribution then at least one property of each fermion must be

different Fermions are usually associated with matter because composite fermions are key building

blocks of matter (neutrons and protons)

Fermionsrsquo behavior by the Fermi-Dirac Statistics which describes the energies of single particles in a

system comprising of many identical particles It applies to identical particles with half-odd integer spin

in a system of thermal equilibrium The particles in the system are assumed to have negligible mutual

interaction This allows the many-particle system to be described in terms of single-particle energy states

The result is the Fermi-Dirac distribution of particles over these states and includes the condition that no

two particles can occupy the same state which has considerable effect on the properties of the system

In quantum mechanics the position of an object is uncertain An object has a definite probability of

being at any given point in space This probability is encoded in the wave function mentioned earlier If

one concentrates a large number of identical bosons in a small region then it is possible for their wave

functions to overlap so much that the bosons lose their identity When this happens thatrsquos a Bose-Einstein

Condensate It is only possible at very low temperatures because at high temperatures the individual

bosons have small wave functions and move rapidly which causes them to fly apart

For now applications are still restricted because there are still some setbacks regarding BECs They

are extremely fragile they are being produced in small quantities with just a few million atoms at a time

and finally they can only be made from certain types of atoms Some examples are the atom laser Ketterle

in which a conventional light lase emits a beam of coherent photons this means they are all in phase and

can be concentrated to an extremely small bright spot BECs can slow down light as demonstrated by

Prof Lene Hau PhD in 2001 by the use of a superfluid [7] These manipulations could develop into

new types of telecommunications technology optical storage and quantum computing

BECs are related to super-fluidity and super-conductivity Super-fluidity is the state of matter in

which the behavior is that of a fluid with zero viscosity It was discovered in liquid helium but now it has

applications in astrophysics high-energy physics and theories of quantum gravity

Super-conductivity is a phenomenon of exactly zero electrical resistance and expulsion of magnetic

fields occurring in certain materials when cooled below a characteristic critical temperature A

super-conductor is shown below in figure 2-12

Fig2-12 Super Conductor

25

232 AR Coating Basic Principles

Anti-reflective (AR) coating is a type of optical coating applied to the surface of lenses and other

optical devices (in our case we planned to apply it to a laser diode) to reduce reflection This improves

the efficiency of the system since less light is lost The primary benefit is the elimination of the reflection

itself

When light the medium (glass) it will produce reflection if 100 of the light comes from the air and

enters the glass because therersquos a difference between the index of refraction some of the light will go out

and when the light is coming out of the glass into the air once again because of the difference between

index of refraction some of the light wonrsquot be able to pass through the medium

When the light makes the first trip into the glass there was a loss of about 4 in the reflection and

when the light makes the trip back outside there was another loss of about 4 so when we assume that

100 of the light interacts with the medium actually therersquos just about 92 acting (we neglect the light

absorbed by the glass around 05) To illustrate this idea please refer to figure 2-13

Fig 2-13 Simple Model for Light in Glass Medium

When we apply the AR Coating the light that enters will only have a loss of about 05 and when

making the trip back outside again only 05 of light is loss so we get the result of increasing the light

passing through up to 99 (again neglecting the light absorbed by the glass around 05) To illustrate

this idea please refer to figure 2-14

26

Fig 2-14 Simple Model for Light in Glass Medium after AR Coating

The AR Coating can reduce reflection of incoming light In the case that light hits perpendicular to

the surface of the medium the intensity of the reflection can be calculated using the Reflection

Coefficient

Where n0 and ns are the refractive indices of the first and second media respectively The value of R

varies from 0 (no reflection) to 1 (all light reflected) and is usually quoted as a percentage

Complementary to R is the transmission coefficient or Transmittance If absorption and scattering are

neglected then the value of Transmittance is always 1-R then if a beam of light with intensity I is

incident on the surface a beam of intensity RI is reflected and a beam with intensity TI is transmitted to

the medium

The optimal value is called the Optimal Index of Refraction and is described as

For glass with ns around 15 in air (n0 around 10) then the optimum refractive index will be n1 =

1225

To reduce the refraction in this case we now mean the one that is produced inside the chamber of the

Laser diode the easiest way is to apply a low reflectivity AR coating on the surface of the laser To

measure the appropriate thickness of the coating layer we can use the equations described above By

applying a coat exactly

thickness film we can assure that a certain wavelength is transmitted The

27

reflected waves from the back of the glass medium will be half a wavelength out of phase So they

interfere destructively Because all reflected waves are interfered the maximum amount of light passes

through the coating Please refer to figure 2-15 to illustrate this idea

Fig 2-15 Light Passing through AR Coat and Glass

The most common process to attain this final product is by vacuum deposition For the best coating

results we need to lower the pressure inside the vacuum system to torr

Fig 2-16 Lens without (Top) and With (Bottom) AR Coating

28

233 Laser Diode Basic Principles

A laser diode is a laser whose active medium is a semiconductor similar to that found in

light-emitting diodes (LEDs) Please refer to figure 2-17 The most common type of laser diode is formed

from a p-n junction and powered by injected electric current

Fig 2-17 Laser Diode

Laser diodes are formed by doping a very thin layer on the surface of a crystal wafer The crystal is

doped to produce the n-type region and a p-type region one above the other

By referring to figure 1-2 we can see the basic structure of a working laser When the laser diode has

a current passing through it the light will get excited inside its gain medium and then will start to

resonate this process is called pumping The current exceeds the critical current and then it comes out as

laser light Please refer to figure 1-3 Since we use an external cavity laser we need to apply the AR

coating to the diode and adjust a diffraction grating The laser light comes out the diode and bounces on

the grating making the resonance externally and this becomes the ldquocavityrdquo as shown in figure 2-18

Fig 2-18 Tunable Laser Basic Configuration

29

The most important feature of the external cavity laser is that we can adjust the wavelength easily just

by changing the diffraction gratingrsquos angle and in the end this is the output wavelength of the laser For

different wavelengths there will be different levels of visible light as shown in figure 2-19

Fig 2-19 Light Spectrum

234 Quartz Microbalance System

A Quartz Crystal Microbalance is an instrument that measures a mass per unit area by measuring the

change in frequency of a quartz crystal resonator The resonance is disturbed by the addition or removal

of a small mass due to oxide growthdecay or film deposition (which is the case in our study) at the

surface of the acoustic resonator The QCM can be used under vacuum in gas phase and more recently in

liquid environments It is useful for monitoring the rate of deposition in thin film deposition systems

under vacuum Frequency measurements are easily made with high precision

For our research we used the Sigma Instruments SQM-160 RateThickness Monitor shown in figure

2-20

Fig 2-20 Front and Back Panels of SQM-160

30

The microbalance uses Quartz as the resonator Quartz is one member of the family of crystals that

experience the Piezoelectric Effect

Piezoelectricity is the charge that accumulates in certain solid materials in response to applied

mechanical stress It means electricity resulting from pressure It was discovered in 1880 by Jacques and

Pierre Curie It is understood as the linear electromechanical interaction between the mechanical and the

electrical state in crystalline materials with no inversion symmetry It is a reversible process in that

materials exhibiting direct piezoelectricity also exhibit the reverse This means that the internal generation

of electrical resulting from applied mechanical force and vice versa

By using the piezoelectric effect we can probe as an acoustic resonance by electrical means Applying

alternating current to the quartz crystal induces oscillations This creates a shear wave We can use these

qualities to determine the resonance frequency at high accuracy

The frequency of oscillation of the crystal is partially dependent in the thickness of the crystal During

normal operation all the variables are held constant so a change in thickness correlates directly to a

change in frequency As mass is deposited or etched away the thickness increases or decreases and so the

frequency of oscillation changes accordingly With some simplifying assumptions the frequency change

can be quantified and correlated precisely to the mass change using the Sauerbreyrsquos Equation

Developed by G Sauerbrey in 1959 it is a method for correlating changes in the oscillation

frequency of a piezoelectric crystal with the mass deposited on it It is defined as below

Where f0 is the Resonant frequency Δf is the Frequency change Δm is the mass change A is the

piezoelectrically active area of the crystal q is the Density of quartz (2648 gcmsup3) and μq is the Shear

modulus of quarts(2947x gcmssup2)

Because the film is treated as an extension of thickness Sauerbreyrsquos equation only applies to systems

in which the following 3 conditions are met

Deposited mass must be rigid

Deposited mass must be distributed evenly

The frequency change

lt002

If the change is greater than 2 the Z-match method must be used to determine the change in mass

It is defined as

Where fL is the frequency of the loaded crystal fU is the resonant frequency Nq is the frequency

constant (1668x HzAring) Δm is the mass change A is the piezoelectrically active area of the crystal

31

q is the density of quartz Z is the method constant f is the density of film μq Is the shear modulus of

quarts and μf is the shear modulus of film

The Sauerbrey equation cannot be applied to systems under liquid medium

The crystals are seed crystals plated with gold on both top and bottom for applications A crystal is

shown in figure 2-21 The QCM consists of a thin piezoelectric plate with electrodes evaporated on both

sides Due to the piezoelectric effect AC voltage across the electrodes induces a shear deformation and

vice versa The electromechanical coupling provides a simple way to detect an acoustic resonance by

electrical means

The Z also called Z-factor is a constant value for different materials and it is shown together with the

density of different materials in table 2-2 below

Fig 2-21 QCM Crystals

The Oscillator of the SQM-160 is shown in figure 2-22 and the equivalent circuit for the Resonant

Oscillator is shown in figure 2-23

Fig 2-22 SQM-160 Oscillator

32

Fig 2-23 Oscillator Circuit

33

Table 2-2 Z-Ratios for Different Materials

Table 2-2 Continued

34

Table 2-2 Continued

35

Table 2-2 Continued

36

Table 2-2 Continued

37

Table 2-2 Continued

38

Table 2-2 Continued

235 Vacuum Chamber System

Vacuum Evaporation is the process of depositing thin films of materials onto surfaces The technique

consists of pumping a vacuum chamber to pressures of less than torr and heating a material to

produce a flux of vapor in order to deposit the material onto a surface The material to be vaporized is

typically heated until its vapor pressure is high enough to produce a flux several Angstrom per second by

using an electrically resistive heater or bombardment by a high voltage beam The process was invented

by Henri Nestle in 1886 for food industry

In here the system has been pumped to a vacuum of Torr When a high current is passed

through the filament boat the filament boat is heated over the desired metal evaporation temperature and

so evaporation starts When the evaporation process is finished and the metal cools down crystals

condensate in the surface of the wafer From the weight of the evaporated material the distance between

the filament boat and the wafer we are able to calculate the deposition thickness and we can also use the

mass detector follower like the Quartz crystal resonator microbalance system In the process of

evaporation we usually use a board in between the filament boat and the wafer This is because before we

arrive to the desired evaporation temperature there will be some impurities that will be vaporized in the

controlled environment so we first use a small current and the board in between to get rid of those

impurities and this raises the purity of the deposition material

39

A vacuum evaporation system is shown in figure 2-24

Fig 2-24 Vacuum Evaporation System

Rough Vacuum 760 ~ 1 torr

Medium Vacuum 1 ~ torr

High Vacuum ~ torr

Ultra-High Vacuum Lower than torr

Table 2-3 Classification of Vacuum

For our study we need to use a Turbo Pump A regular turbo pump is shown in figure 2-25

Fig 2-25 Turbo Pump

For our research we used the Pfeiffer TCP 015 Electronic Drive Unit and Granville Phillips 375

Convectron shown below in figure 2-26

40

Fig 2-26 Control and Measurement Equipment

The electronic drive controls the turbo pump and the Convectron measures the pressure inside our

chamber The turbo pump is a type of vacuum pump used to maintain high vacuum Most turbo pumps

are centrifugal When we start the pumping we need to use a mechanical pump so as to decrease the

pressure inside the system from constant atmospheric pressure to torr and then the use dispersion

pump to continue the vacuum until we get to the desired pressure We need to notice though when we

start the dispersion pump we canrsquot turn off the mechanical pump and they both need to run together If

we need to turn off the pumping we first turn off the dispersion pump wait for it to completely stop and

then turn off the mechanical pump

Our completely assembled system is shown in figure 2-27 below

Fig 2-27 Complete System

41

Chapter 3 TENSILE TESTING IN DEPTH

31 Experimentrsquos Purpose and Principles

By means of Universal testing machine and Strain gauges we were able to observe discuss and

analyze the phenomena created when a specimen of certain material is manipulated under an external load

and determine the stress strain and deformation values later we can use the graphing methods of

stress-strain diagram to describe it

The main point of this experiment is that after the tensile specimen is tested use computer analysis

and the actual strain data and after statistical adjustment make the final results report (Tensile testing

experiment is in accordance with ASTM E8)

32 Experimentrsquos Equipment

321 Universal Testing Machine

For the materials testing experiment part of this research we use a Universal Testing Machine as

shown in figure 31 The maximum load it can apply is 100 Ton After the test specimen is secured on the

device with the use of instrumentation the load exerted and the effects of this become apparent on the

specimen and even the smallest of changes can be recorded For our research we used the Chun Yen

Testing Machines Co Ltd 100 Ton Micro Computer Universal Tensile Tester

Fig 31 Universal Testing Machine

42

Table 31 shows the specifications for this machine

Max Capacity 100 Ton

Accuracy plusmn1

Tension (mm) Max Space 1150mm

Grip for Rod 20-70mm

Ram Stroke 250mm

Effective Column Interval 940mm

Crosshead Speed 300mmmin

Testing Speed 0-50mmmin

Volume of Machine 1700times1000times3350mm(LtimesWtimesH)

Volume of Control Panel 1000times800times1500mm(LtimesWtimesH)

Weight 8000kg

Power 3∮220V 20A

Computer AMD K6-2-350

OS Windows XP

Screen 15rdquo CRT

Table 3-1 Chun Yen Testing Machine Specs Table

The connections diagram is shown in figure 3-2

Fig 3-2 Diagram for System Connections

43

When the test specimen is placed when the external force is applied the Load Cell can measure the

size of the applied force and the Encoder measures the expansion rate of change The Local Controller

receives all the information from the 2 units after arranging the results they are displayed in the

computer and they can be afterwards submitted for more complex analysis such as Finite Element

Analysis and we can get the Stress-Strain Diagram

322 Strain Measurement Equipment

The equipment used in our research provides a four-channel measurement that means we can use up

to 4 strain gauges at a time to do our measurements and provides 3 different bridge arrangements as

shown in figure 3-3

(a) (b) (c)

Fig 3-3 Input Connections for Strain Indicator

Figure 3-3 (a) is the Quarter Bridge (b) is the Half Bridge and (c) is the Full Bridge and Transducers

For our study we used the Quarter Bridge and use the Strain Gauge values to decide the position of the

connecting wires The Strain indicator is shown in figure 3-4

Fig 3-4 Vishay Micro-Measurements Model P3 Strain Indicator and Recorder

44

Input Connections Tool Free eccentric lever release

4-channel input

Wire diameter16-28AWG

Bridge Configurations Quarter- Half- and Full Bridge

Bridge Impedance 60-2000Ω

Display 128 64 pixel FSTN positive gray LCD

Data Conversion AD Converter filter

Measurement Range Resolution Strain Range plusmn155mVV

Resolution plusmn00005mVV

Measurement Accuracy plusmn01 of reading plusmn3 counts

Gage Factor Control 0500-9900

Balance Control Software either manual or automatic

Bridge Excitation 15VDC nominal

Communication Interface USB Cable Included

Data Storage Removable Media Card

Shunt Calibration Across bridge completion resistors controlled

by software When Gage Factor=200

120Ω350Ω1000Ω

Analog Output Value 0 to 25V max

Ranges plusmn320 microε plusmn3200 microε plusmn32000 microε

Error 05 output voltage +5mV

Max Error 14 output voltage + 20mV

Update rate 480 samplessec

Output Load 2000Ω

Power Battery Two Alkaline D cells

Battery life 400 hours typ

USB 5V 100mA

Operational Environment Temperature 0-50

Humidity Up to 90 Non-condensing

Case Aluminum Alloy

Size and Weight 228times152times152(mm) 20(kg)

Table 3-2 Vishay Micro-Measurements Model P3 Strain Indicator and Recorder Specs

45

323 Strain Gauge

The strain gaugersquos main basic principle is to use a resistancersquos characteristics to measure the strain

The inside connections of the strain indicator are shown in figure 3-5

Fig 3-5 Inner Connections

As shown above this is a quarter-bridge connection We connect equal-length 3 wires to the 2

connections allowed by the strain gauge wire 1 and 3 can be used to cancel out the effects of temperature

to the resistance and because of the addition of wires 1 and 3 wire 2 can directly measure the experiment

results from the strain gauge and therefore the strain developed with no influence of temperature

If there were no two measuring leads then the relations will be

R 4 =R g +2R L

Where Rg is the Strain Gauge Value and RL is the wire resistance then

4

4

R

R=

Lg

g

RR

R

2

=

gL

gg

RR

RR

21

amp

4

4

R

R=

g

g

R

R(1- L)

Where L is the Signal Loss Factor and so

L =gL

gL

RR

RR

21

2

g

L

R

2R if

g

L

R

2Rltlt1

46

(Actual Value R g =120R L =08g

L

R

2Ris always much smaller than 1)

R 4 =R g +2R LR 2 =R 3 =rR gR 1 =R g 32 RR =0

V 0 =V 2)1( r

r

(

4

4

R

R-

1

1

R

R)

The first term describes loss attenuation effects second term describes loss of balancing capabilities

effects

V 0 =V 2)1( r

r

[

)2

(Lg

g

RR

R

+

T

Lg

g

RR

R

)

2( + T

Lg

L

RR

R

)

2

2( -(

g

g

R

R) T ]

The first term describes loss attenuation effects and loss of balancing capabilities effects the second

third and fourth terms describe the temperature effects on the wire

For the three-wire method we have

L =gL

gL

RR

RR

1

g

L

R

R if

g

L

R

Rltlt1

V 0 =V 2)1( r

r

[

)(Lg

g

RR

R

+

T

Lg

g

RR

R

)( + T

Lg

L

RR

R

)

2( -

T

Lg

g

RR

R

)( - T

Lg

L

RR

R

)

2( ]

V 0 = V2)1( r

r

)(

Lg

g

RR

R

In the last four terms inside parenthesis we can see the effects of temperature being cancelled out and the

effect on first term is not great so this is the reason why in our research we use three wires

47

324 Specimen Measurements

The tensile specimens used in this research are compliant of ASTM E8 Tensile parameters as shown

in figure 3-6

Fig 3-6 Tensile Specimen

Diameter

D(mm)

Gauge

Length

G(mm)

Smallest

Arc

Radius

R(mm)

Shortest

Area

A(mm)

Total

Length

L(mm)

Clamping

Area

Length

B(mm)

Clamping

Area

Diameter

C(mm)

Bar 125 02 625 01 gt10 gt75 ~ 145 ~ 35 20

Table 3-3 Specifications for Round Bar

33 Experiment Procedure

1 Attaching the Strain Gauge to the Tensile Specimen

(1) Prepare 1 ASTM E8 compliant tensile specimen round bar as shown in figure 3-7

(2) Prepare Strain Gauge as those described in table 3-4

(3) Prepare other consumables and adhesive agent such as epoxy adhesive or

cyanoacrylate adhesive as shown in figure 3-8

48

Fig 3-7 Actual Tensile Specimen

Fig 3-8 Other Materials Used (Such as Alcohol gauze transparent tape adhesive)

Gage Type

EA-06-120LZ-120E

Resistance in ohms at 24∘C

1200plusmn03

Gage Factor at 24∘C

2075plusmn05

Transverse Sensitivity at 24∘C

(+07plusmn02)

Table 3-4 Specifications for Strain Gauge

2 Attaching Strain Gauge

As shown in following figures we shall explain the attachment of the strain gauge

(1) Use sand paper and a rasp to clean thoroughly the surface where the strain gauge will be

attached to

49

(a)

(2) Use alcohol to wash the surface where the strain gauge will be attached and use gauze to rub

it off

(b)

(3) Find a clean surface and clean it with alcohol and gauze

(c)

(4) Place the strain gauge in the clean surface Use a piece of transparent tape on top of the strain

gauge after securely placed rip it off the surface carefully

50

(d)

(5) Use a piece of white paper to mark the place where the strain gauge will be attached and in

this way we can make sure that the strain gauge will be placed as horizontally and vertically

correct as possible

(e)

(6) In the place where we had our mark place the strain gauge

(f)

(7) Carefully lift one side of the tape and apply some of the adhesive agent to both the strain

gauge and specimenrsquos surface

(g)

51

(8) We need to make sure that the gauge and the specimen will be firmly attached so we gently

apply pressure with our thumb

(h)

(9) After the adhesive is fully dry we can carefully rip off the tape

(i)

(10) We need to do the whole process twice one for the horizontally placed strain gauge and one

for the vertically placed strain gauge

52

(j)

(11) We now proceed to solder the wires to the strain gauge

(k)

(12) After soldering we use a Volt Multimeter to measure that there is no contact between wires

If there is none then the specimen is ready for testing

(l)

(13) We now need to measure a 5cm distance and mark it to check and compare the elongation

before and after the tensile testing

(m)

53

Fig 3-9 Specimen-Strain Gauge Process

3 Tensile Test

(1) Enter the computer application that controls the tensile testing machine

(2) Turn on the tensile testing machine main switch

(3) Adjust the hydraulic pump to go back to its original position

(4) Bring the lowering motor down to a distance enough so as to attach the tensile specimen to the

system open the clamps and secure the specimen

(a)

(5) Connect all the necessary wires to the strain indicator equipment

54

(b)

(6) Start the ascending motor and wait for the expansion

(c)

Fig 3-10 Specimen-Tensile Testing Process

4 Start the Test

(1) Enter the software application and enter some variables needed for the experiment in the

specific screen

(2) Go back to the main screen and press the [測試] (measure) button to start the test and auto

recording in the software

(3) After the specimen breaks the mechanical device will automatically stop and ask the user to

enter the total displacement We take out the specimen from the testing machine and adjust the

machinersquos position back to its original position

(4) Save the results information

(5) Record the results from the strain indicator

34 Results

From this experiment we can get the Poissonrsquos Ratio Youngrsquos Modulus and Yield Strength etc and

because of the slippage phenomenon in the clamp at the moment of the test then the Elastic Limit will

display some yield phenomena So omit any undesirable results we just take the Yield portion of the

results as reference

In the process of the experiment the most important part to attend to is the attaching of the strain

gauge because the gaugersquos purpose is to measure the strain developed during the test and this strain

might be very small If the gaugersquos angle change during the test ie is not well attached this will affect

the accuracy of the measurements of Poissonrsquos ratio and Youngrsquos modulus

55

The materials provided by the manufacturer are SUM 23 and SUM 43 steel round bars and these two

types of materials have been through different heat treatment processes so they can be sub-divided

further into untreated material heat-treated material and black surface heat treated material for the two

materials with heat treatment the treatment process and finished are different In the end we only have

the mechanical properties that were calculated after our research of these materials

All of the specifications are identical to those shown in figure 3-6

341 SUM 23

Fig 3-11 SUM 23 Untreated Material

Number 7 10

Hardness(HRB) 74 75

Yield Stress (MPa) 448 440

Tensile Strength (MPa) 544 560

Poissonrsquos Ratio 029 027

Youngrsquos Modulus (GPa) 203 210

Cut-off Area Shrinking () 42 41

Elongation () 1125 1011

Table 3-5 Mechanical Properties of SUM 23 Untreated

56

Stress-Strain Diagram

(a)

(b)

57

Fig 3-12 Stress-Strain Diagrams for (a) 7 Round Bar and (b) 10 Round Bar

Cut-Off Area

(a)

(b)

Fig 3-13 Cut-Off Area of (a) 7 Round Bar and (b) 10 Round Bar

58

SUM 23 Nickel Round Bar

Fig 3-14 SUM 23 Nickel Material

Number 1 2 3 4

Hardness(HRB) 48 50 49 48

Yield Stress (MPa) 370 370 380 400

Tensile Strength (MPa) 455 451 450 450

Poissonrsquos Ratio 028 046 029 026

Youngrsquos Modulus (GPa) 243 303 246 206

Cut-off Area Shrinking () 803 803 726 601

Elongation () 566 65 602 647

Table 3-6 Mechanical Properties of SUM 23 Nickel

59

Stress-Strain Diagram

(a)

60

(b)

(c)

(d)

61

Fig 3-15 Stress-Strain Diagrams for (a) 1 Round Bar (b) 2 Round Bar (c) 3 Round Bar and (d)

4 Round Bar

Cut-Off Area

(a)

(b)

62

(c)

(d)

Fig 3-16 Cut-Off Area of (a) 1 Round Bar (b) 2 Round Bar (c) 3 Round Bar and (d) 4 Round

Bar

63

SUM 23 Black Surface Round Bar

Fig 3-17 SUM 23 Black Surface Material

Number 1 2 3

Hardness(HRB) 51 50 51

Yield Stress (MPa) 378 371 369

Tensile Strength (MPa) 467 465 464

Poissonrsquos Ratio 03 016 04

Youngrsquos Modulus (GPa) 215 266 266

Cut-off Area Shrinking () 986 94 848

Elongation () 748 805 761

Table 3-7 Mechanical Properties of SUM 23 Black Surface Material

64

Stress-Strain Diagram

(a)

(b)

65

(c)

Fig 3-18 Stress-Strain Diagrams for (a) 1 Round Bar 2 Round Bar and (c) 3 Round Bar

Cut-Off Surface

(a)

66

(b)

(c)

Fig 3-19 Cut-Off Surface of (a) 1 Round Bar 2 Round Bar and (c) 3 Round Bar

67

342 SUM 43

Fig 3-20 Untreated SUM 43 Untreated Material

Number 1 5

Hardness(HRB) 76 75

Yield Stress (MPa) 572 594

Tensile Strength (MPa) 743 785

Poissonrsquos Ratio 027 029

Youngrsquos Modulus (GPa) 200 202

Cut-off Area Shrinking () 338 2944

Elongation () 857 894

Table 3-8 Mechanical Properties of SUM 43 Untreated

68

Stress-Strain Diagrams

(a)

(b)

Fig 3-21 Stress-Strain Diagrams for SUM 43 (a) 1 Round Bar and (b) 5 Round Bar

69

Cut-Off Area

(a)

(b)

Fig 3-22 Cut-Off Area of SUM 43 (a) 1 Round Bar and (b) 5 Round Bar

70

SUM 43 Nickel Round Bar

Fig 3-23 SUM 43 Nickel Material

Number 4 5

Hardness(HRB) 51 50

Yield Stress (MPa) 1580 1544

Tensile Strength (MPa) 1639 1625

Poissonrsquos Ratio 03 028

Youngrsquos Modulus (GPa) 194 201

Cut-off Area Shrinking () 1697 137

Elongation () 376 265

Table 3-9 Mechanical Properties of SUM 43 Nickel

71

Stress-Strain Diagrams

(a)

(b)

Fig 3-24 Stress-Strain Diagrams for (a) 4 Round Bar and (b) 5 Round Bar

72

Cut-Off Area

(a)

(b)

Fig 3-25 Cut-Off Area of (a) 4 Round Bar and (b) 5 Round Bar

73

SUM 43 Black Surface Material

Fig 3-26 SUM 43 Black Surface Material

Number 3 5

Hardness(HRB) 56 56

Yield Stress (MPa) 1416 1361

Tensile Strength (MPa) 1591 1402

Poissonrsquos Ratio 029 031

Youngrsquos Modulus (GPa) 200 202

Cut-off Area Shrinking () 139 124

Elongation () 24 24

Table 3-10 Mechanical Properties of SUM 43 Black Surface Material

74

Stress-Strain Diagrams

0 2 4 6 8 10 12 14

-200

0

200

400

600

800

1000

1200

1400

1600

1800

應力 (MPa)

應變()

(a)

0 2 4 6 8 10

-200

0

200

400

600

800

1000

1200

1400

1600

應力

(MPa)

位移 ()

(b)

Fig 3-27 Stress-Strain Diagrams for (a) 3 Round Bar and (b) 5 Round Bar

(Note These curves were formulated using Visual Solutions Inc VisSim Software)

75

Cut-Off Area

(a)

(b)

Fig 3-28 Cut-Off Area of (a) 3 Round Bar and (b) 5 Round Bar

76

The force value (N) was retrieved from the Universal Testing Machine

The Poissonrsquos Ratio (ε) is calculated as

ε =

the values for the Poissonrsquos Ratio are in average around 0297

The Youngrsquos Modulus (E) is calculated as

E =

Where

Stress =

Cross-sectional Area =

where D is the Diameter

The value for D was in average around 1258 mm

The values shown by the computer because there is Slippage phenomena between the Clamp and the

specimen will not be taken into consideration for the elongation strain and Youngrsquos modulus and we will

refer to the values that we have meticulously calculated

77

Chapter 4 AR COATING IN DEPTH

41 Experimentrsquos Purpose and Principles

By means of a vacuum chamber and several other instruments we intend to apply Anti-Reflective

Coating using deposition process to a laser diode and in this way reduce its refraction so as to make it

lose less light in the process of amplification and we can control certain wavelengths we want produced

for certain desired applications in our case we are attempting to re-create a Bose-Einstein Condensate

An optimal BEC apparatus is shown in figure 4-1

Fig 4-1 BEC Apparatus

The main point of this experiment is to build a vacuum chamber system attach all the instrumentation

needed (Vacuum pump deposition meter and voltmeter) and use it to apply AR coating to a laser diode

After we have accomplished the AR coating other team will be in charge of designing the BEC apparatus

and use the results of our research

78

42 Experimentrsquos Equipment

421 Vacuum Chamber

For this research we designed a vacuum chamber whose main body is shown in figure 4-2 Its

dimensions are

Width 240 mm

Length 240 mm

Height 200 mm

Outer Diameter 4 in

Inner Diameter 15 in

Fig 4-2 Vacuum Chamber Main Body

The chamber is made up of 6 pass ways pass way A is the connection with the Laser Deposition

Equipment pass way B is the connection with the Turbo Pump and pass way C is for the connection with

the Deposition Source

A

C

B

79

Pass way C is for the deposition source as mentioned above This is a system where a thermal

resistance is heated by passing a high current through it which heats up a filament boat (made of tungsten)

where the material to be evaporated is place We control the temperature as such that the material will

evaporate and the heat will not cause the filament boat to crack

Because P = Isup2 R (where P is power I is current and R is resistance) to avoid the current to flow

where it is not desired we decided that the material for the Thermocouple shown in figure 4-3 should be

Copper ᴓ 63 mm We choose it that way because Copper has very good heat dissipation characteristics

and the resistance value is low It can reduce the value of the current enough to make the thermocouple to

create heat

Fig 4-3 Thermocouple

To the thermocouple we attach the tungsten filament boat We need to take notice of materials to be

used in this design because when using high current the tungsten filament boar will heat up and so the

material must be able to keep up with the heating potential of tungsten and has a low coefficient of heat

dissipation to avoid the tungsten to fail when heating up and therefore not evaporating Considering all

this we decide to use Stainless Steel

Because this clamp will be assembled inside the chamber after many revisions it was determined it

will have the shape shown in figure 4-4

Fig 4-4 Filament Boat Clamp Design

80

For the tungsten filament boat we bought the product from a distributor The dimensions are

Length 100 mm

Width 10 mm

Height 1 mm

Our thermocouple is 15 in but the pass way C is 4 in so we need to attach a Flange that connects

15in to 4in Because these specifications are quite difficult to achieve by Milling we had to use

electrical wire cutting

For the laser clamping system where the laser that is going to be AR coated will be placed will be

connected to pass way A the assembly is shown in figure 4-5 below

Fig 4-5 Cover Assembly

For this design we used an O-ring instead of a gasket so as to save time The design of the assembly

where the laser will be placed is shown in figure 4-6

Fig 4-6 Upper Cover Inner Assembly

D

E

F

81

Point D is the plate in the assembly where the laser diode will be fixed Because of the easy

processing we decide to use Aluminum and it is screwed to the top cover Point E is the connection for

the Quartz crystal resonator and it is designed in the same as point F in this way the results of the quartz

microbalance system will be more accurate in real time Point F is the final resting place for the laser

diode We use a Thor Labs Base with dimensions of ᴓ 9mm and ᴓ 56mm for two different size laser

diodes It just needs to be plugged in for easy installation

From figure 4-6 we know that the system needs signal system connections and because of the

change in temperature inside the chamber this could affect the functioning of the quartz microbalance so

we also need to install water tubes for cooling This is shown in figure 4-7 below

Fig 4-7 Diagram of Upper Cover Connections

In figure 4-8 we show the Feed through connections and their functions

Fig 4-8 Feed through Diagram

82

1 SQM-160 wire 5 Laser Connection 1 (Vin)

2 SQM-160 (G) 6 Laser Connection 2 (G)

3 K-Type-1 7 Laser Connection 3 (PD)

4 K-Type-2 8 Not In Use

The fully assembled chamber is shown in figure 4-9

Fig 4-9 Fully Assembled Chamber

422 Quartz Crystal Microbalance

For measuring the deposition on our target for coating we used the Inficon SQM-160 RateThickness

Monitor It is an easy to use instrument for measuring many types of thin-film coatings as shown in

figure 4-10

(a) Front Panel (b) Back Panel

Fig 4-10 Inficon SQM-160

83

Table 4-1 shows the technical specifications for this equipment

Number of sensors 2 Standard 4 additional optional

Sensor Frequency Range 40 MHz ~ 60 MHz

Reference Frequency Accuracy 002

Thickness Display Resolution 1 Aring

Thickness Resolution 015 Aring (Std) 0037 Aring (Hi Res)

Density of Stored Films 05-9999 gmcc

Tooling 10-399

Z-Factor 010-1000

Final Thickness 0000-9999k Aring

Measurement Period 15 to 2 sec

Simulation Mode Yes

Frequency Mode Yes

Rate Resolution 011 Arings

Dual Crystal Yes

Etch Mode Yes

Crystal Tooling 10-399

Crystal Fail Min Max 40 to 60 MHz 41 to 61 MHz

Power 100-120 200-240~plusmn10 nominal 20W

Operation Environment 0degC ~ 50degC

0 ~ 80 RH non-condensing

0 ~ 2000 meters

Class 1 Equipment

Pollution Degree 2

Rack Dimensions 885mm x 2127mm x 1969mm

Weight 27 kg

Table 4-1 Inficon SQM-160 RateThickness Monitor Specs

84

To the SQM-160 we need to connect an Oscillator We use the Sigma Instruments Remote Oscillator

Ser No 2 268 as shown in figure 4-11

Fig 4-11 Sigma Instruments Remote Oscillator

The connections diagram is shown in figure 4-12

Fig 4-12 SQM-160 Connections Diagram

85

423 Turbo Pump

For our experiments we used the Pfeiffer TCP 015 Electronic Drive Unit shown below in figure 4-13

Table 4-2 shows the technical specifications for this equipment

(a) Front Panel (b) Back Panel

Fig 4-13 Pfeiffer TCP 015 Electronic Drive

Connection Voltage (100V) 90-112

Mains Frequency 5060 Hz

Start-up Current 22 A

Nominal Frequency 1500 Hz

Rotation Speed 10V = 1500Hz plusmn2

Analog Output Current 10 V = 25 A plusmn 5

Rotation Speed Switchpoint 750 Hz

Works Setting 8 min

Permissible Ambient Temperature 0degC ~ 40degC

Dimensions Front Panel 1285mm x 1063mm

Insertion Length 227mm

Weight 27 Kg

Table 4-2 Pfeiffer TCP 015 Electronic Drive Specs

86

The connections diagram is shown in figure 4-14

Fig 4-14Connections Diagram for Pfeiffer TCP 015

To measure the pressure inside the chamber we use the Granville Phillips 375 Convectron Vacuum

Pressure Controller shown in figure 4-15

(a) Front Panel (b) Back Panel

Fig 4-15 Granville Phillips 375 Convectron

87

Its dimensions are shown in figure 4-16

Fig 4-16 Dimensions of Convectron

Table 4-3 shows the technical specifications for this equipment

Table 4-3 Granville Phillips 375 Convectron Vacuum Pressure Controller Specs

88

424 Multimeter

For our experiment we used the Keithley 2000 Digital Multimeter as shown in figure 4-17

(a) Front Panel (b) Back Panel

Fig 4-17 Keithley Model 2000 6-12-Digit Digital Multimeter

Its technical specifications are shown in table 4-4

Table 4-4 Keithley Model 2000 6-12-Digit Digital Multimeter Specs

89

43 Experiment Procedure

1 Connecting together the equipment and the chamber

(1) We first connect the resonator to the thickness monitor and connect the other side to the

chamber

(2) We now connect the flexible tubes to the turbo pump on one side and to the chamber on the

other

(3) We need to check that tubes are tightly connected to avoid any leaks in the vacuum pumping

process which will not allow us to get to our goal of Torr As shown in figure 4-18

(4) Connect the convectron to the system as shown in figure 4-19

Fig 4-18 checking for leaks using alcohol

Fig 4-19 Convectron attached to System

90

(5) Attach the clamps of the Multimeter to the bottom of the chamber as shown in figure 4-20

(6) Place the Quartz crystal in place

(7) Close tight vacuum chamber

(8) Connect all electrical appliances to power source

Fig 4-20 Multimeter Connections

2 Starting up the System

(1) We turn on all the devices as such Check all systems are ready to function Reset all values

that might be left over from previous tests

(2) Start the thickness monitor and set all values for this experiment In our case we got to testing

the system but not actual coating So we used the simulation mode of the thickness monitor as

shown in figure 4-21

Fig 4-21 Simulation Mode

91

(3) Start the turbo pump Make sure the lid on the vacuum chamber is tightly closed

(4) Start convectron and record initial pressure

(5) Start Multimeter and record initial current

3 Coating Process

(1) If we have the deposition material inside the filament boat the power source for the high

current must be started as well

(2) Record all initial values for thickness current pressure

(3) For an ideal experiment we need a thickness of around 101 nm a pressure of Torr and

a current of 300 A

44 Results

From previous experiments we have shown that we can turn a LED into a laser by means of AR

Coating In figure 4-22 shown below we can compare the actual results of a Diode before and after AR

coating From the blue line we can see that when the diode is at a current of 15mA its light will change

from LED to laser and if we look at the red line its critical current is around 30 to 35 mA

Fig 4-22 AR Coating Comparison for Laser Diodes

This means that the light emitted is not as strong as if the diode had been coated because inside the

chamber there must be some excitation first so the reflectivity of both sides inside the diode must be high

So because of the coating in one of the sides we have opened a door and let the light come out so the

critical current is risen as such and will be higher value than that of before the coating

92

In the following figures we can see the difference between before and after coating in a material The

thickness is around 1016 nm for this material

Fig 4-23 Before Coating

Fig 4-24 After Coating

93

Chapter 5 CONCLUSIONS AND RECOMMENDATIONS

51 Conclusions

For the first part of this independent study taking into consideration the data that came out of our

research and that sent by the provider we can say

1 SUM 23 after heat treatment will unexpectedly develop cracking in the middle of the tensile

testing process and suddenly break

2 Itrsquos possible that in the process of heat treatment to the SUM 23 material the treatment was not

uniform and this will create a pre-loaded moment force on one side that pushes on the other side

of the specimen resulting in material deformation

3 In the process of attaching the strain gauges to the materials it is very easy to make errors due to

poor adhesion or sudden removal in the tensile testing process

For our second part of the independent study the following can be made

1 At the beginning of this independent study we had no idea what Bose-Einstein Condensate was

or what was its purpose After much literature we finally comprehended the basic principles to

put into practice for our research

2 Our systemrsquos basic working principles and equipmentrsquos complexity are a little difficult to grasp

but hopefully we were able to understand enough of it

3 Theoretically from relation between the power and current we can know the advantages and

disadvantages of AR Coating

4 We were able to assemble the system and run test on its functions Even though we were able to

do this there is still much more work left to do with this system

52 Recommendations

For the Tensile Testing the following can be said

1 Ask the provider to check on the process of heat treatment on the SUM 23 material and give

them the information we have gathered through our test so they can correct for the mechanical

properties found if any change is needed

2 To avoid the problem of the inaccuracy of the poor adhesion of strain gauges we can attach

multiple strain gauges to the same one specimen so as to correlate data and improve our results

For the AR Coating the following can be said

1 We need to make sure that there are no physical defects on the main body of the chamber so as to

achieve maximum efficiency in the vacuum process If there was then the vacuum will arrive to

certain point and then start to decrease

2 It would be preferable to add some sort of visual aid that will allow the user to check the inside of

the chamber without actually opening it This will help us determine at what times we should

manipulate the current to better evaporate the substrate

94

REFERENCES

[1] A L Window Strain Gauge Technology Elsevier Applied Science London and New York 2nd

Edition 1992

[2] CC Perry and HR Lissner Strain Gauge Primer McGraw-Hill Book Co Inc New York 1955

[3] James W Dally William F Riley McGraw-Hill 1978

[4] University of Colorado Boulder BEC - What is it and where did the idea come from

httpwwwcoloradoeduphysics2000becwhat_is_ithtml

[5] Ultraslow Light amp Bose-Einstein Condensates Two-way Control with Coherent Light amp Atom

Fields Harvard Hau Lab Dr Lene Vestergaard Hau Optics amp Photonics News 16 1995

[6] The Art of Taming Light Ultra-slow and Stopped Light Harvard Hau Lab Dr Lene

Vestergaard Hau Europhysics News 2004

[7] Nonlinear Optics Shocking Superfluids Harvard Hau Lab Dr Lene Vestergaard Hau Nature

Physics 2007

[8] Model P3 Strain Indicator and Recorder Instruction Manual Vishay Micro-Measurements 2005

[9] Granville-Phillips Series 375 Convectron Vacuum Gauge Controller Instruction Manual Brooks

Automation 2008

[10] Effect of Film Thickness on the Validity of the Sauerbrey Equation for Hydrated Polyelectrolyte

Films Vogt Lin Wu White 2004

[11] Quartz Crystal Microbalance Study of DNA Immobilization and Hybridization for DNA Sensor

Development Chang Zhao 2008

[12] Installation of Strain Gages with SR-4 PrecoatAdhesive Vishay Micro-Measurements 2005

[13] Strain Gauge Measurement ndash A Tutorial National Instruments 1998

[14] Correlation between Vickers Hardness Number and Yield Stress of Cold-Formed Products

Yavuz Tekkaya

[15] httpsenwikipediaorg

Page 4: PC Hinge Materials Testing and AR Laser Diode Coating

4

ACKNOWLEDGEMENT

First and foremost I would like to thank God I would never have done this study without the

faith I have in you the Almighty

I would like to thank my parents Gloria Iveth Sanchez and Juan Carlos Bonilla my sisters

Joanna Iveth Bonilla Karla Ines Bonilla and Kelly Gabriela Bonilla and my entire family for

their love support patience and understanding during my 5 years of studying abroad

I owe my deepest gratitude to my advisor Professor Ho-Chiao Chuang PhD for letting me

carry out this study Without his support and comprehension this study would have never been

carried out

Special thanks to Institute of Atomic and Molecular Sciences Academia Sinica Dr

Ming-Shien Chang for without him I would not be able to understand and put into practice

some of the principles presented in this thesis

I am indebted to many friends and classmates for the invaluable support during my studies in

this country and in this University

A special mention to my beloved friends Christian Reyes Francisco Garcia Jose Pagoada

and Olvin Castillo to my classmates 姚呈忠 王煜璨 林炯宇 for helping me during my tough

times my senior 廖梃君 and my junior 石中鈺 for thanks to them I was able to work and

present results during the course of this research and everyone else involved at the Department

of Mechanical Engineering at National Taipei University of Technology

5

TABLE OF CONTENTS

ABSTRACThelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 2

ACKNOWLEDGEMENThelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 4

TABLE OF CONTENTShelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 5

LIST OF TABLEShelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 7

LIST OF FIGUREShelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 8

CHAPTER 1 Introductionhelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 10

11 Motivation and Backgroundhelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 10

12 Research Objectivehelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 11

13 Methodologyhelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 13

14 Organization of the Thesishelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 13

CHAPTER 2 Basic Principleshelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 14

21 Tensile Testinghelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 14

211 Youngrsquos Modulushelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 14

212 Yield Strength and Yield Pointhelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 15

213 Ultimate Tensile Strength and Breaking Strengthhelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 16

214 Poissonrsquos Ratiohelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 16

215 Strain Gauge Basic Principleshelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 16

22 Hardness Test Basic Principleshelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 18

221 Brinell Scale BHNhelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 18

222 Rockwell Scale HRhelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 19

223Vickers Hardness Test HVhelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 21

23 AR Coatinghelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 22

231 Bose-Einstein Condensatehelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 22

232 AR Coating Basic Principleshelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 25

233 Laser Diode Basic Principleshelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 28

234 Quartz Microbalance Systemhelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 29

235 Vacuum Chamber Systemhelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 38

CHAPTER 3 Tensile Testing in depthhelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 41

31 Experimentrsquos Purpose and Principleshelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 41

32 Experimentrsquos Equipmenthelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 41

321 Universal Testing Machinehelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 41

322 Strain Measurement Equipmenthelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 43

6

323 Strain Gaugehelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 45

324 Specimen Measurementshelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 47

33 Experiment Procedurehelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 47

34 Resultshelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 54

341 SUM 23helliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 55

342 SUM 43helliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 67

CHAPTER 4 AR Coating in depthhelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 77

41 Experimentrsquos Purpose and Principleshelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 77

42 Experimentrsquos Equipmenthelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 78

421 Vacuum Chamberhelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 78

422 Quartz Microbalancehelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 82

423 Turbo Pumphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 85

423 Multimeterhelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 88

43 Experiment Procedurehelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 89

44 Resultshelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 91

CHAPTER 5 Conclusions and Recommendationshelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 93

51 Conclusionshelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 93

52 Recommendationshelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 93

REFERENCEShelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 94

7

LIST OF TABLES

Table 2-1 Rockwell Hardness Test Scalehelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 20

Table 2-2 Z-Ratios for Different Materialshelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 33

Table 2-3 Classifications of Vacuumhelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 39

Table 3-1 Chun Yen Testing Machine Specshelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 42

Table 3-2 Vishay Micro-Measurements Model P3 Strain Indicator and Recorder Specshelliphelliphelliphelliphelliphellip 44

Table 3-3 Specifications for Round Barhelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 47

Table 3-4 Specifications for Strain Gaugehelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 48

Table 3-5 Mechanical Properties of SUM 23 Untreatedhelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 55

Table 3-6 Mechanical Properties of SUM 23 Nickelhelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 58

Table 3-7 Mechanical Properties of SUM23 Black Surface Materialhelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 63

Table 3-8 Mechanical Properties of SUM 43 Untreatedhelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 67

Table 3-9 Mechanical Properties of SUM 43 Nickelhelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 70

Table 3-10 Mechanical Properties of SUM 43 Black Surface Materialhelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 73

Table 4-1 Inficon SQM-160 RateThickness Monitor Specshelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 83

Table 4-2 Pfeiffer TCP 015 Electronic Drive Specshelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 85

Table 4-3 Granville Phillips 375 Convectron Vacuum Pressure Controller Specshelliphelliphelliphelliphelliphelliphelliphelliphellip 87

Table 4-4 Keithley Model 2000 6-12-Digit Digital Multimeter Specshelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 88

8

LIST OF FIGURES

Fig 1-1 Notebook Computer Hingehelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 11

Fig 1-2 Basic Structure of Laserhelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 11

Fig 1-3 Comparison between LED and Laser Diodehelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 12

Fig 1-4 External Cavity Designhelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 12

Fig 2-1 Stress-Strain Curvehelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 14

Fig 2-2 Stress-Strain Curve Comparison on Metalshelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 15

Fig 2-3 Basic Structure of Strain Gaugehelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 17

Fig 2-4 Strain Gauge Attached to Wheatstone Bridgehelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 18

Fig 2-5 Brinell Indentationhelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 18

Fig 2-6 Brinell Hardness Testerhelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 18

Fig 2-7 Rockwell Indentationhelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 19

Fig 2-8 Rockwell Hardness Testerhelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 19

Fig 2-9 Vickers Indentationhelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 22

Fig 2-10 Vickers Hardness Testerhelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 22

Fig 2-11 Bose-Einstein Condensate at different scaleshelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 23

Fig 2-12 Super Conductorhelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 24

Fig 2-13 Simple Model for Light in Glass Mediumhelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 25

Fig 2-14 Simple Model for Light in Glass Medium after AR Coatinghelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 26

Fig 2-15 Light Passing through AR Coating and Glasshelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 27

Fig 2-16 Lens without and with AR Coatinghelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 27

Fig 2-17 Laser Diodehelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 28

Fig 2-18 Tunable Laser Basic Configurationhelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 28

Fig 2-19 Light Spectrumhelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 29

Fig 2-20 Front and Back Panel of SQM-160helliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 29

Fig 2-21 QCM Crystalshelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 31

Fig 2-22 SQM-160 Oscillatorhelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 31

Fig 2-23 Oscillator Circuithelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 32

Fig 2-24 Vacuum Evaporation Systemhelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 39

Fig 2-25 Turbo Pumphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 39

Fig 2-26 Control and Measurement Equipmenthelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 40

Fig 2-27 Complete Systemhelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 40

Fig 3-1 Universal Testing Machinehelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 41

Fig 3-2 Diagram for System Connectionshelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 42

Fig 3-3 Input Connections for Strain Gaugehelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 43

Fig 3-4 Vishay Micro-Measurements Model P3 Strain Indicator and Recorderhelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 43

Fig 3-5 Inner Connectionshelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 45

Fig 3-6 Tensile Specimenhelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 47

Fig 3-7 Actual Tensile Specimenhelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip47

Fig 3-8 Other Materials Usedhelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 48

Fig 3-9 Specimen-Strain Gauge Processhelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 49

Fig 3-10 Specimen-Tensile Testing Processhelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 53

9

Fig 3-11 SUM 23 Untreated Materialhelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 55

Fig 3-12 Stress-Strain Diagrams for 7 and 10 Round Barhelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 56

Fig 3-13 Cut-Off Area of 7 and 10 Round Barhelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 57

Fig 3-14 SUM 23 Nickel Materialhelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 58

Fig 3-15 Stress-Strain Diagrams for 1 2 3 and 4 Round Barhelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip60

Fig 3-16 Cut-Off Area of 1 2 3 and 4 Round Barhelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 62

Fig 3-17 SUM 23 Black Surface Materialhelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 63

Fig 3-18 Stress-Strain Diagrams for 1 2 and 3 Round Barhelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 65

Fig 3-19 Cut-Off Area of 1 2 and 3 Round Barhelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 66

Fig 3-20 SUM 43 Untreated Materialhelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip67

Fig 3-21 Stress-Strain Diagrams for 1 and 5 Round Barhelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 68

Fig 3-22 Cut-Off Area of 1 and 5 Round Barhelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 69

Fig 3-23 SUM 43 Nickel Materialhelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 70

Fig 3-24 Stress-Strain Diagrams for 4 and 5 Round Barhelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 71

Fig 3-25 Cut-Off Area of 4 and 5 Round Barhelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 72

Fig 3-26 SUM 43 Black Surface Materialhelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 73

Fig 3-27 Stress-Strain Diagrams for 3 and 5 Round Barhelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 74

Fig 3-28 Cut-Off Area of 3 and 5 Round Barhelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 75

Fig 4-1 BEC Apparatushelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 77

Fig 4-2 Vacuum Chamber Main Bodyhelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 78

Fig 4-3 Thermocouplehelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip79

Fig 4-4 Filament Boat Clamp Designhelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 79

Fig 4-5 Cover Assemblyhelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 80

Fig 4-6 Upper Cover Inner Assemblyhelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 80

Fig 4-7 Diagram of Upper Cover Connectionshelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 81

Fig 4-8 Feed Through Diagramhelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 81

Fig 4-9 Fully Assembled Chamberhelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 82

Fig 4-10 Inficon SQM-160helliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 82

Fig 4-11 Sigma Instruments Remote Oscillatorhelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 84

Fig 4-12 SQM-160 Connections Diagramhelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 84

Fig 4-13 Pfeiffer TCP 015 Electronic Drivehelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 85

Fig 4-14 Connections Diagram for Pfeiffer TCP 015helliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 86

Fig 4-15 Granville Phillips 375 Convectronhelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 86

Fig 4-16 Dimensions of Convectronhelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 87

Fig 4-17 Keithley Model 2000 6-12-Digit Digital Multimeterhelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 88

Fig 4-18 Checking for Leaks Using Alcoholhelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 89

Fig 4-19 Convectron Attached to Systemhelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 89

Fig 4-20 Multimeter Connectionshelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 90

Fig 4-21 Simulation Modehelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 90

Fig 4-22 AR Coating Comparison for Laser Diodeshelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 91

Fig 4-23 Before AR Coatinghelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 92

Fig 4-24 After AR Coatinghelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 92

10

Chapter 1 INTRODUCTION

11 Motivation and Background

In response that new generation computers are gradually reducing their size the diameter of

the structures of the hinges used by NB computers must also follow but the hinge strength may

also become smaller due to the reduction of diameter and result in the phenomenon of

insufficient strength In addition the disk-type spring that is source of the torque may also be

insufficient due to the narrowing of the structure Therefore it is necessary to direct a structural

analysis of the hinge for the existing laptops so that we can identify the stress concentration

point The stress concentration point is usually the point where material damage behavior is

encountered the easiest and if we can find the point where breaking occurs most often we can

improve the design of the existing structure to enhance the strength of the hinge structure

Second the structure of the hinge is too complicated the traditional mechanics of materials

analysis methods and formulas are no longer suitable for analysis of a wide arrange of hinge

design In recent years finite element analysis methods have been widely applied in various

fields such as electronics machinery aviation and so on

Therefore to meet the need of the industry and with the purpose of reducing design time

how to design a notebook computer hinge without compromising mechanical stability and

materialrsquos hardness which will operate equally under equal conditions In other words be able to

meet the needs of the size decreasing NB computers market as the needs for this kind of

accessories will increase in the near future If we take into consideration the traditional ways of

design we seek to reduce the costs of use of machinery and molding by applying Finite Element

Analysis methods to our study and also increase the flexibility of designing methods

The second project was brought in by Prof Chuang and it is to help in the further research of

the Bose-Einstein condensate This is a state of matter of a dilute gas weakly interacting bosons

(subatomic particles that obey the Bose-Einstein statistics) confined in an external potential and

cooled down to temperatures very near absolute zero (0 K or -27315deg C) Under these conditions

a large number of bosons occupy the lowest quantum state of the external potential at which

point quantum effects become apparent at macroscopic scale This state of matter was predicted

by Satyendra Nath Bose and Albert Einstein in 1924~1925 Then 70 years later the 1st gaseous

condensate was produced by Eric Cornell and Carl Wieman in 1995 at the University of

Colorado (Boulder) NIST-JILA lab and because of this along with Wolfgang Ketterle of MIT

they received the 2001 Nobel Prize in Physics

11

We wish to investigate the properties of Anti Reflecting Coating on laser diodes Hopefully

we will be able to achieve the desired effect of reducing the surface reflection coefficient and

find applications for it

12 Research Objective

We wish to analyze the normal composition of the notebook computerrsquos hinge at which

point in the assembly is clearly the weakest and at this time in the assembly the strength and

durability are influenced The main point is to see if we can affect the normal operation and work

life

The objective of this thesis is to present the results of the material properties under tensile

testing find the mechanical properties and after using finite element analysis determine what

material is the best for our purposes

Fig 1-1 Notebook Computer Hinge

For our second research we wish to produce and analyze laser diodes with anti-reflective

coating and test its properties and applications

When semi-conductor laser has been submitted to current it will produce resonance inside it

and light will be stimulated to come out Please refer to figure 1-2 for the basic structure of a

laser

Fig 1-2 Basic Structure of a Laser

1 Gain Medium

2 Laser Pumping Energy

3 High Reflector

4 Output Coupler

5 Laser Beam

12

But when the laser diode generates light but the laser diode canrsquot produce light on itself it

must wait for the current to be higher than certain value which is called the critical current Until

the light goes over this threshold then it is considered laser light if not it is just considered as a

common LED light source Please refer to figure 1-3

Fig 1-3 Comparison between LED and Laser Diode

As we can see from figure 1-3 all of the light that goes over the critical current is laser light

and so the external cavity semi-conductor laser that we built needs Anti-Reflective Coating

because the method we want to use needs an external cavity laser that has been covered with AR

Coating and a Diffraction Grating We use this configuration first by shooting the laser to the

grating and this will be shot back to the laser creating the external resonance cavity which is

shown in figure 1-4

Fig 1-4 External Cavity Design

13

Two configurations are shown the Littrow Configuration and the Littman-Metcalf

Configuration The Littrow configuration contains a collimating lens and a diffraction grating as

the end mirror The first order diffracted beam provides optical feedback to the laser diode which

has AR Coating The emission wavelength can be turned by rotating the diffraction grating A

disadvantage is that it also changes the direction of the output beam

In the Littman-Metcalf configuration the grating orientation is fixed and an additional mirror

is used to reflect the first order beam back to the laser diode The wavelength can be turned by

rotating that mirror This configuration offers a fixed direction of the output beam and also tends

to exhibit smaller line width as the wavelength selectivity is stronger A disadvantage is that

zero order reflection of the beam reflected by the tuning mirror is lost so that the output power is

less than that of a Littrow laser

13 Methodology

The aim of this research is to find the mechanical properties of materials after being

subjected to tensile testing through finite element analysis observations and determine what

material is best for our purposes taking into consideration the strength and durability of the

material among other properties to find use and applications for the AR coated laser diodes to

further improve the grasp of the Bose-Einstein condensation working principles

14 Organization of the Thesis

The research paper includes five chapters

1 Chapter 1 explains the motivation background objective and methodology of this study

2 Chapter 2 explains the working principles and basic knowledge needed to understand this

study

3 Chapter 3 explains the tensile testing in detail steps methods and results

4 Chapter 4 explains the AR coating in detail steps methods and results

5 Chapter 5 is the conclusions taken from the results shown in chapter 3 and 4 and

recommendations done after arranging and critical thinking

14

Chapter 2 BASICS THEORIES

21 Tensile Testing

After a specimen is tested with the use of tensile testing we can get the Stress-Strain Curve using the

relation between tension and displacement Typical curves are shown in Fig 2-1

(a) Ductile materials (b) Brittle materials

Fig 2-1 Stress-Strain Curve

The curve is unique for each material and is found by recording the amount of deformation at distinct

intervals of tensile or compressive loads Thanks to the use of the Stress-Strain curve we can get very

useful information such as

211 Youngrsquos Modulus (E)

As shown in Fig 2-1 as long as the external load is not greater than the Proportional Limit the Stress

(σ) and Strain (ε) remain as a linear relation fulfilling Hookersquos Law

σ = Eε

The slope is the constant factor the inverse of the modulus of elasticity E also called Youngrsquos

modulus When the external load goes over the proportional limit the stress-strain relationship doesnrsquot

follow the linear relation anymore but the deformation remains flexible When the load is released the

deformation is completely eliminated and the specimen goes back to its original state This is called

15

Elastic Deformation When the external load goes over the Elastic limit only then does the specimen

presents Plastic Deformation This type of deformation which is irreversible even when the load is

removed comes after the material does under elastic deformation so this means the object will first come

part way to its original shape Common metals and ceramics have roughly the same elastic limits

212 Yield Strength and Yield Point

Some materials display very evident yield phenomena while some materials donrsquot as shown in Fig

2-2 After we exceed the elastic limit if we continue to exert load when we arrive to a certain value

which differs under different materials and external conditions there is sudden decrease in stress and this

is called the Yield Strength and can be defined as the stress at which a material begins to deform

plastically using the equation

σyield =

Where P is the tension force and Ao is the original cut-off area

The stress remain at a certain value after the decrease but the strain increases this phenomena can be

easily appreciated when studying the behavior of common Carbon Steel Fig2-2 (a) but most metals (like

Aluminum Copper or High Steel Carbon) donrsquot display this kind of behavior as shown in Fig 2-2 (b)

Arriving to this point is very difficult and the most commonly used method for this is to add a 02 or

0002 offset yield strength to the curve This point is held constant on the strain axis of the curve and

from the 0002 position we draw a straight line parallel to the linear relationship line the point at where

this line and the stress-strain curve intercept is the point we take as the 02 offset yield strength

(a)Evident (b) Non-evident

Fig2-2 Stress-Strain Curve Comparison on Metals

16

213 Ultimate Tensile Strength and Breaking Strength

After materials undergo yield they keep lending strength and hardening phenomena occurs (work

hardening) on the material and the external load increases When it has reached the highest point this is

called the Ultimate Tensile Strength (UTS) as shown in Fig2-1 The UTS is defined as

σUTS =

Where Pmax is the load at the materialrsquos ultimate tensile strength point and Ao is the original cut-off

area For brittle materials the ultimate tensile strength is the most important mechanical property for

ductile materials the ultimate tensile strength is not commonly used for industrial and designing purposes

because upon arriving to this value the material already has forgone great plastic deformation After the

specimen goes through UTS there will be necking phenomena which is a mode of tensile deformation

where relatively large amounts of strain localize disproportionately in a small region of the material It

results from instability during tensile deformation when a materialrsquos cross-sectional area decreases by a

greater proportion than the material strain hardens The specimen continues to elongate until it finally

breaks and the load at this point is called Breaking Strength The breaking strength is defined as the

greatest stress in tension that a material is capable of withstanding without rupture

Where Pf is the load at the materialrsquos breaking strength point and Ao is the original cut-off area

214 Poissonrsquos Ratio (ν)

For elastic deformation when materials are compressed in one direction they tend to expand in the

other two directions perpendicular to the direction of compression This is called the Poissonrsquos Effect

The Poison Ratio is a measure of the Poissonrsquos effect It is the ratio of the fraction of expansion divided

by the fraction of compression for small values of these changes

ν=-

215 Strain Gauge Basic Principles

The strain gauge is a device used to measure the strain of an object Itrsquos an elongated metal resistor

which is attached to the specimen being measured and when the specimen is under strain and starts to

deform the strain gauge will have a change in the resistance With the change in value we can calculate

the elementrsquos strain or elastic modulus and the Poissonrsquos ratio

It takes advantage of the physical property of electrical conductance and its dependence on the

conductorrsquos geometry When the electrical conductor (the specimen being tested) is stretched within the

limits of elasticity such that it does not break or deform plastically it will become narrower and longer

17

which increases the electrical resistance through-out From the measured resistance of the strain gauge

the amount of stress may be inferred by using the relations

R=

Where R is the original resistance value is the electrical resistivity lo is the original length of the

conductor and Ao is the original cross sectional area of the conductor If after the application of tension

the change in length is Δl let the length of the specimen be l = l + Δlo and the tension is the same

through-out So

And the resistance is

The Gauge Factor is the ratio of relative change in electrical resistance to the mechanical strain in

other words it is the relative change in length It is defined as

The strain gauge was invented in 1938 by Edward E Simmons and Arthur C Ruge and the most

common type consists of an insulating flexible backing which supports a metallic foil usually made of a

brass-nickel alloy It is attached to the specimen by a suitable adhesive As the object is deformed the foil

also deforms and this causes the electrical resistance to change Then this is usually measured using a

Wheatstone bridge shown below and is related to the strain by the Gauge Factor

Fig2-3 Basic Structure of Strain Gauge

18

Fig 2-4 Strain gauge attached to Wheatstone bridge

22 Hardness Testing Basic Principles

221 Brinell Scale BHN

The Brinell Scale characterizes the indentation hardness of materials through the scale of penetration

of an indenter loaded on a material specimen The typical test uses a 10mm diameter steel ball as indenter

(usually of value equal to BHN450) with a 29kN force For softer materials smaller force is used The

indentation is measured and BHN is calculated using the relation

BHN =

radic

Where F is the applied force usually within the range of 100 250 500 750 1000 1500 2000 2500

and 3000 kgf D is the diameter of indenter usually within the range of 5mm or 10mm plusmn0005 margin

and d is the diameter of indentation usually around 2mm Its units are of Kgmmsup2 but are not normally

written

First proposed by Swedish engineer Johan August Brinell in 1900 it was the first widely used and

standardized hardness test in engineering and metallurgy although the large size of indentation and

possible damage to specimen limits its usefulness

Fig 2-5 Brinell Indentation Fig2-6 Brinell Hardness Tester

19

222 Rockwell Scale HR

The Rockwell scale is a hardness scale based on the indentation hardness of a material The Rockwell

test determines the hardness by measuring the depth of penetration of an indenter under a large load

compared to the penetration made by a preload The indenter is forced into the specimen under a

preliminary load When equilibrium is reached a measuring device follows the movements of the

indenter and responds to changes in depth of penetration of the indenter While the preload is still being

applied additional major load is applied resulting in increased penetration When equilibrium is reached

again the major load is removed but the preload is maintained Removing the major load allows partial

recovery and reduces the depth of penetration The permanent increase in depth of penetration resulting

from the application and removal of the major load is used to calculate the Rockwell number using the

relation

HR = E ndash e

Where E is a constant depending on the form of the indenter 100 units for diamond indenter and 130

units for steel ball indenter e is the permanent increase in depth of penetration due to the major load

measured in units of 0002mm

Fig 2-7 Rockwell Indentation

When testing materials indentation hardness is related linearly to the tensile strength The important

relation permits economically important nondestructive testing of bulk metal deliveries with lightweight

equipment like the Rockwell tester shown below in figure 2-7

Fig 2-8 Rockwell Hardness Tester

20

There are different scales denoted by a single letter that use different loads or different indenters

The result is a dimensionless number denoted as HR X where X will be the letter denoting the scale as

shown below in table 2-1

Table 2-1 Rockwell Hardness Test Scale

Differential depth hardness measurement was first conceived in 1908 by Viennese professor Paul

Ludwik It eliminated the errors associated with the mechanical imperfections of the system such as

backlash and surface imperfections in the specimen Rockwell testing has an advantage over Brinell

testing because the latter was slow itrsquos not useful on fully hardened steel and left too large an impression

to be considered nondestructive

The tester was co-invented by Hugh M Rockwell and Stanley P Rockwell The requirement for this

tester was to quickly determine the effects of heat treatment on steel bearing races

21

223 Vickers Hardness Test HV

This is a type of microindentation hardness test where a diamond indenter of specific geometry is

impressed into the surface of the test specimen using a known applied force ranging from 10 to 1000

grams This type of tests usually has forces of 2N and produce indentations of about 50μm They can be

used to observe changes in hardness on the microscopic scale It is difficult to standardize the

microhardness measurements because it has been found that the microhardness of almost any material is

higher than its macrohardness The values also vary with load and work-hardening effects of materials

The Vickers test is often easier to use than other hardness tests because the required calculations are

independent of the size of the indenter and the indenter can be used for all materials It can be used for all

metals and has one of the widest scales among hardness tests The unit of the Vickers test is denoted as

HV and can be converted to units of Pascal (Pa) but it is not a measurement of pressure The hardness

number is determined by the load over the surface area of the indentation and not the area normal to the

force

A square-based pyramid shaped diamond is use as the indenter It has been established that the ideal

size of a Brinell impression was 38 of the ball diameter As two tangents to the circle at the ends of a

chord 3d8 long intersect at 136plusmn05deg it was decided to use this as the angle of the indenter giving an

angle to the horizontal plane of 22deg on each side The HV number is determined by the ratio FA where F

is the force applied to the diamond in kgf and A is the surface area of the resulting indentation in mmsup2 A

can be determined by the relation

A =

Where A is the surface area of indentation and d is the average length diagonal left by the indenter

This can be approximated as

A =

Then the Vickers Number is

HV =

=

Vickers hardness number is reported as xxxHVyy or xxxHVyyzz (if duration of applied force differs

from 10s to 15s) where xxx are replaced by the hardness number yy is the load in kg and zz indicates

loading time The values are generally independent of test force

The test was developed in 1921 by Robert L Smith and George E Sandland at Vickers Ltd as an

alternative to Brinell method to measure the hardness of materials

22

Fig 2-9 Vickers Indentation Fig 2-10 Vickers Hardness Tester

23 AR Coating

231 Bose-Einstein Condensate

The Bose-Einstein Condensate or BEC is a state of matter of a dilute gas of bosons cooled to

temperatures very near absolute zero around 0K or -27315degC Under such conditions a large fraction of

the bosons occupy the lowest quantum state where the quantum effects become apparent on a

macroscopic scale This gave birth to the Bose-Einstein Statistics which are the rules that govern the

behavior at this state It is one of the two possible ways in which a collection of indistinguishable particles

may occupy a set of available discrete energy states The aggregation of particles in the same state

accounts for the cohesive streaming of laser light and the frictionless creeping of superfluid helium (an

application discussed later) Bose and Einstein recognized that a collection of identical and

indistinguishable particles can be distributed this way This theory applies only to those particles not

limited to single occupancy of the same state particles that do not obey the Pauli Exclusion Principle

restrictions Such particles are the Bosons named after the statistics that correctly describe their behavior

This phenomenon was first predicted by Satyendra Nath Bose around 1924 when he considered how

groups of photons behave He then asked Albert Einstein for help publishing his discoveries to which

Einstein agreed and gave follow up supporting these findings The resulting efforts became the concept of

a Bose gas governed by the Bose-Einstein Statistics described above Einstein demonstrated that cooling

bosonic atoms to a very low temperature would cause them to condense into the lowest accessible

quantum state resulting in a new form of matter

The first gaseous condensate we produced by Eric Cornell and Carl Wieman at the University of

Colorado at Boulder NIST ndash JILA lab sung a gas of rubidium atoms cooled to 170 nK which earned

them the 2001 Nobel Prize in physics together with Wolfgang Ketterle from MIT The transition to BEC

occurs below a critical temperature which for a uniform three dimensional gas consisting of

non-interacting particles with no apparent internal degrees of freedom is given by

23

Tc =

(

)

asymp 33125

Where Tc is the critical temperature n is the particle density m is the mass per boson h is the

reduced Planck constant k is the Boltzmann constant and ζ is the Riemann zeta function

There are two classes of elementary particles defined by whether their quantum spin is a nonnegative

integer or an odd half integer A Bose-Einstein Condensate is shown below in figure 2-11

Fig 2-11 Bose Einstein Condensate at different scales

Bosons are the particles whose quantum spin is a nonnegative integer (s = 0 1 2 etc) Examples of

bosons include fundamental particles (Higgs Boson Photons W and Z Bosons Gluons Gravitons etc)

composite particles (Mesons Hadrons Nuclei and Atoms of Carbon-12 and Helium-4) and

quasi-particles Bosons are considered force carrier particles The Bosons differ from Fermions in that

there is no limit to the number that can occupy the same quantum state This is called the Pauli Exclusion

Principle

The Pauli Exclusion Principle says that no two identical fermions may occupy the same quantum state

simultaneously in other words this means that the total wave function for two identical fermions is

anti-symmetric with respect to exchange of the particles This means that no two electrons in a single

atom can have the same four quantum numbers

Fermion is any particle characterized by Fermi-Dirac Statistics and follows the Pauli Exclusion

Principle described above Quarks Leptons and composite particles (Hadrons Nuclei and Atoms of

Carbon-13 and Helium-3) made of an odd number of these are considered Fermions It can be an

elementary particle such as the electron or a composite particle such as the protons Following the Pauli

24

Exclusion Principle only one fermion can occupy a particular quantum state at any given time If multiple

fermions have the same spatial probability distribution then at least one property of each fermion must be

different Fermions are usually associated with matter because composite fermions are key building

blocks of matter (neutrons and protons)

Fermionsrsquo behavior by the Fermi-Dirac Statistics which describes the energies of single particles in a

system comprising of many identical particles It applies to identical particles with half-odd integer spin

in a system of thermal equilibrium The particles in the system are assumed to have negligible mutual

interaction This allows the many-particle system to be described in terms of single-particle energy states

The result is the Fermi-Dirac distribution of particles over these states and includes the condition that no

two particles can occupy the same state which has considerable effect on the properties of the system

In quantum mechanics the position of an object is uncertain An object has a definite probability of

being at any given point in space This probability is encoded in the wave function mentioned earlier If

one concentrates a large number of identical bosons in a small region then it is possible for their wave

functions to overlap so much that the bosons lose their identity When this happens thatrsquos a Bose-Einstein

Condensate It is only possible at very low temperatures because at high temperatures the individual

bosons have small wave functions and move rapidly which causes them to fly apart

For now applications are still restricted because there are still some setbacks regarding BECs They

are extremely fragile they are being produced in small quantities with just a few million atoms at a time

and finally they can only be made from certain types of atoms Some examples are the atom laser Ketterle

in which a conventional light lase emits a beam of coherent photons this means they are all in phase and

can be concentrated to an extremely small bright spot BECs can slow down light as demonstrated by

Prof Lene Hau PhD in 2001 by the use of a superfluid [7] These manipulations could develop into

new types of telecommunications technology optical storage and quantum computing

BECs are related to super-fluidity and super-conductivity Super-fluidity is the state of matter in

which the behavior is that of a fluid with zero viscosity It was discovered in liquid helium but now it has

applications in astrophysics high-energy physics and theories of quantum gravity

Super-conductivity is a phenomenon of exactly zero electrical resistance and expulsion of magnetic

fields occurring in certain materials when cooled below a characteristic critical temperature A

super-conductor is shown below in figure 2-12

Fig2-12 Super Conductor

25

232 AR Coating Basic Principles

Anti-reflective (AR) coating is a type of optical coating applied to the surface of lenses and other

optical devices (in our case we planned to apply it to a laser diode) to reduce reflection This improves

the efficiency of the system since less light is lost The primary benefit is the elimination of the reflection

itself

When light the medium (glass) it will produce reflection if 100 of the light comes from the air and

enters the glass because therersquos a difference between the index of refraction some of the light will go out

and when the light is coming out of the glass into the air once again because of the difference between

index of refraction some of the light wonrsquot be able to pass through the medium

When the light makes the first trip into the glass there was a loss of about 4 in the reflection and

when the light makes the trip back outside there was another loss of about 4 so when we assume that

100 of the light interacts with the medium actually therersquos just about 92 acting (we neglect the light

absorbed by the glass around 05) To illustrate this idea please refer to figure 2-13

Fig 2-13 Simple Model for Light in Glass Medium

When we apply the AR Coating the light that enters will only have a loss of about 05 and when

making the trip back outside again only 05 of light is loss so we get the result of increasing the light

passing through up to 99 (again neglecting the light absorbed by the glass around 05) To illustrate

this idea please refer to figure 2-14

26

Fig 2-14 Simple Model for Light in Glass Medium after AR Coating

The AR Coating can reduce reflection of incoming light In the case that light hits perpendicular to

the surface of the medium the intensity of the reflection can be calculated using the Reflection

Coefficient

Where n0 and ns are the refractive indices of the first and second media respectively The value of R

varies from 0 (no reflection) to 1 (all light reflected) and is usually quoted as a percentage

Complementary to R is the transmission coefficient or Transmittance If absorption and scattering are

neglected then the value of Transmittance is always 1-R then if a beam of light with intensity I is

incident on the surface a beam of intensity RI is reflected and a beam with intensity TI is transmitted to

the medium

The optimal value is called the Optimal Index of Refraction and is described as

For glass with ns around 15 in air (n0 around 10) then the optimum refractive index will be n1 =

1225

To reduce the refraction in this case we now mean the one that is produced inside the chamber of the

Laser diode the easiest way is to apply a low reflectivity AR coating on the surface of the laser To

measure the appropriate thickness of the coating layer we can use the equations described above By

applying a coat exactly

thickness film we can assure that a certain wavelength is transmitted The

27

reflected waves from the back of the glass medium will be half a wavelength out of phase So they

interfere destructively Because all reflected waves are interfered the maximum amount of light passes

through the coating Please refer to figure 2-15 to illustrate this idea

Fig 2-15 Light Passing through AR Coat and Glass

The most common process to attain this final product is by vacuum deposition For the best coating

results we need to lower the pressure inside the vacuum system to torr

Fig 2-16 Lens without (Top) and With (Bottom) AR Coating

28

233 Laser Diode Basic Principles

A laser diode is a laser whose active medium is a semiconductor similar to that found in

light-emitting diodes (LEDs) Please refer to figure 2-17 The most common type of laser diode is formed

from a p-n junction and powered by injected electric current

Fig 2-17 Laser Diode

Laser diodes are formed by doping a very thin layer on the surface of a crystal wafer The crystal is

doped to produce the n-type region and a p-type region one above the other

By referring to figure 1-2 we can see the basic structure of a working laser When the laser diode has

a current passing through it the light will get excited inside its gain medium and then will start to

resonate this process is called pumping The current exceeds the critical current and then it comes out as

laser light Please refer to figure 1-3 Since we use an external cavity laser we need to apply the AR

coating to the diode and adjust a diffraction grating The laser light comes out the diode and bounces on

the grating making the resonance externally and this becomes the ldquocavityrdquo as shown in figure 2-18

Fig 2-18 Tunable Laser Basic Configuration

29

The most important feature of the external cavity laser is that we can adjust the wavelength easily just

by changing the diffraction gratingrsquos angle and in the end this is the output wavelength of the laser For

different wavelengths there will be different levels of visible light as shown in figure 2-19

Fig 2-19 Light Spectrum

234 Quartz Microbalance System

A Quartz Crystal Microbalance is an instrument that measures a mass per unit area by measuring the

change in frequency of a quartz crystal resonator The resonance is disturbed by the addition or removal

of a small mass due to oxide growthdecay or film deposition (which is the case in our study) at the

surface of the acoustic resonator The QCM can be used under vacuum in gas phase and more recently in

liquid environments It is useful for monitoring the rate of deposition in thin film deposition systems

under vacuum Frequency measurements are easily made with high precision

For our research we used the Sigma Instruments SQM-160 RateThickness Monitor shown in figure

2-20

Fig 2-20 Front and Back Panels of SQM-160

30

The microbalance uses Quartz as the resonator Quartz is one member of the family of crystals that

experience the Piezoelectric Effect

Piezoelectricity is the charge that accumulates in certain solid materials in response to applied

mechanical stress It means electricity resulting from pressure It was discovered in 1880 by Jacques and

Pierre Curie It is understood as the linear electromechanical interaction between the mechanical and the

electrical state in crystalline materials with no inversion symmetry It is a reversible process in that

materials exhibiting direct piezoelectricity also exhibit the reverse This means that the internal generation

of electrical resulting from applied mechanical force and vice versa

By using the piezoelectric effect we can probe as an acoustic resonance by electrical means Applying

alternating current to the quartz crystal induces oscillations This creates a shear wave We can use these

qualities to determine the resonance frequency at high accuracy

The frequency of oscillation of the crystal is partially dependent in the thickness of the crystal During

normal operation all the variables are held constant so a change in thickness correlates directly to a

change in frequency As mass is deposited or etched away the thickness increases or decreases and so the

frequency of oscillation changes accordingly With some simplifying assumptions the frequency change

can be quantified and correlated precisely to the mass change using the Sauerbreyrsquos Equation

Developed by G Sauerbrey in 1959 it is a method for correlating changes in the oscillation

frequency of a piezoelectric crystal with the mass deposited on it It is defined as below

Where f0 is the Resonant frequency Δf is the Frequency change Δm is the mass change A is the

piezoelectrically active area of the crystal q is the Density of quartz (2648 gcmsup3) and μq is the Shear

modulus of quarts(2947x gcmssup2)

Because the film is treated as an extension of thickness Sauerbreyrsquos equation only applies to systems

in which the following 3 conditions are met

Deposited mass must be rigid

Deposited mass must be distributed evenly

The frequency change

lt002

If the change is greater than 2 the Z-match method must be used to determine the change in mass

It is defined as

Where fL is the frequency of the loaded crystal fU is the resonant frequency Nq is the frequency

constant (1668x HzAring) Δm is the mass change A is the piezoelectrically active area of the crystal

31

q is the density of quartz Z is the method constant f is the density of film μq Is the shear modulus of

quarts and μf is the shear modulus of film

The Sauerbrey equation cannot be applied to systems under liquid medium

The crystals are seed crystals plated with gold on both top and bottom for applications A crystal is

shown in figure 2-21 The QCM consists of a thin piezoelectric plate with electrodes evaporated on both

sides Due to the piezoelectric effect AC voltage across the electrodes induces a shear deformation and

vice versa The electromechanical coupling provides a simple way to detect an acoustic resonance by

electrical means

The Z also called Z-factor is a constant value for different materials and it is shown together with the

density of different materials in table 2-2 below

Fig 2-21 QCM Crystals

The Oscillator of the SQM-160 is shown in figure 2-22 and the equivalent circuit for the Resonant

Oscillator is shown in figure 2-23

Fig 2-22 SQM-160 Oscillator

32

Fig 2-23 Oscillator Circuit

33

Table 2-2 Z-Ratios for Different Materials

Table 2-2 Continued

34

Table 2-2 Continued

35

Table 2-2 Continued

36

Table 2-2 Continued

37

Table 2-2 Continued

38

Table 2-2 Continued

235 Vacuum Chamber System

Vacuum Evaporation is the process of depositing thin films of materials onto surfaces The technique

consists of pumping a vacuum chamber to pressures of less than torr and heating a material to

produce a flux of vapor in order to deposit the material onto a surface The material to be vaporized is

typically heated until its vapor pressure is high enough to produce a flux several Angstrom per second by

using an electrically resistive heater or bombardment by a high voltage beam The process was invented

by Henri Nestle in 1886 for food industry

In here the system has been pumped to a vacuum of Torr When a high current is passed

through the filament boat the filament boat is heated over the desired metal evaporation temperature and

so evaporation starts When the evaporation process is finished and the metal cools down crystals

condensate in the surface of the wafer From the weight of the evaporated material the distance between

the filament boat and the wafer we are able to calculate the deposition thickness and we can also use the

mass detector follower like the Quartz crystal resonator microbalance system In the process of

evaporation we usually use a board in between the filament boat and the wafer This is because before we

arrive to the desired evaporation temperature there will be some impurities that will be vaporized in the

controlled environment so we first use a small current and the board in between to get rid of those

impurities and this raises the purity of the deposition material

39

A vacuum evaporation system is shown in figure 2-24

Fig 2-24 Vacuum Evaporation System

Rough Vacuum 760 ~ 1 torr

Medium Vacuum 1 ~ torr

High Vacuum ~ torr

Ultra-High Vacuum Lower than torr

Table 2-3 Classification of Vacuum

For our study we need to use a Turbo Pump A regular turbo pump is shown in figure 2-25

Fig 2-25 Turbo Pump

For our research we used the Pfeiffer TCP 015 Electronic Drive Unit and Granville Phillips 375

Convectron shown below in figure 2-26

40

Fig 2-26 Control and Measurement Equipment

The electronic drive controls the turbo pump and the Convectron measures the pressure inside our

chamber The turbo pump is a type of vacuum pump used to maintain high vacuum Most turbo pumps

are centrifugal When we start the pumping we need to use a mechanical pump so as to decrease the

pressure inside the system from constant atmospheric pressure to torr and then the use dispersion

pump to continue the vacuum until we get to the desired pressure We need to notice though when we

start the dispersion pump we canrsquot turn off the mechanical pump and they both need to run together If

we need to turn off the pumping we first turn off the dispersion pump wait for it to completely stop and

then turn off the mechanical pump

Our completely assembled system is shown in figure 2-27 below

Fig 2-27 Complete System

41

Chapter 3 TENSILE TESTING IN DEPTH

31 Experimentrsquos Purpose and Principles

By means of Universal testing machine and Strain gauges we were able to observe discuss and

analyze the phenomena created when a specimen of certain material is manipulated under an external load

and determine the stress strain and deformation values later we can use the graphing methods of

stress-strain diagram to describe it

The main point of this experiment is that after the tensile specimen is tested use computer analysis

and the actual strain data and after statistical adjustment make the final results report (Tensile testing

experiment is in accordance with ASTM E8)

32 Experimentrsquos Equipment

321 Universal Testing Machine

For the materials testing experiment part of this research we use a Universal Testing Machine as

shown in figure 31 The maximum load it can apply is 100 Ton After the test specimen is secured on the

device with the use of instrumentation the load exerted and the effects of this become apparent on the

specimen and even the smallest of changes can be recorded For our research we used the Chun Yen

Testing Machines Co Ltd 100 Ton Micro Computer Universal Tensile Tester

Fig 31 Universal Testing Machine

42

Table 31 shows the specifications for this machine

Max Capacity 100 Ton

Accuracy plusmn1

Tension (mm) Max Space 1150mm

Grip for Rod 20-70mm

Ram Stroke 250mm

Effective Column Interval 940mm

Crosshead Speed 300mmmin

Testing Speed 0-50mmmin

Volume of Machine 1700times1000times3350mm(LtimesWtimesH)

Volume of Control Panel 1000times800times1500mm(LtimesWtimesH)

Weight 8000kg

Power 3∮220V 20A

Computer AMD K6-2-350

OS Windows XP

Screen 15rdquo CRT

Table 3-1 Chun Yen Testing Machine Specs Table

The connections diagram is shown in figure 3-2

Fig 3-2 Diagram for System Connections

43

When the test specimen is placed when the external force is applied the Load Cell can measure the

size of the applied force and the Encoder measures the expansion rate of change The Local Controller

receives all the information from the 2 units after arranging the results they are displayed in the

computer and they can be afterwards submitted for more complex analysis such as Finite Element

Analysis and we can get the Stress-Strain Diagram

322 Strain Measurement Equipment

The equipment used in our research provides a four-channel measurement that means we can use up

to 4 strain gauges at a time to do our measurements and provides 3 different bridge arrangements as

shown in figure 3-3

(a) (b) (c)

Fig 3-3 Input Connections for Strain Indicator

Figure 3-3 (a) is the Quarter Bridge (b) is the Half Bridge and (c) is the Full Bridge and Transducers

For our study we used the Quarter Bridge and use the Strain Gauge values to decide the position of the

connecting wires The Strain indicator is shown in figure 3-4

Fig 3-4 Vishay Micro-Measurements Model P3 Strain Indicator and Recorder

44

Input Connections Tool Free eccentric lever release

4-channel input

Wire diameter16-28AWG

Bridge Configurations Quarter- Half- and Full Bridge

Bridge Impedance 60-2000Ω

Display 128 64 pixel FSTN positive gray LCD

Data Conversion AD Converter filter

Measurement Range Resolution Strain Range plusmn155mVV

Resolution plusmn00005mVV

Measurement Accuracy plusmn01 of reading plusmn3 counts

Gage Factor Control 0500-9900

Balance Control Software either manual or automatic

Bridge Excitation 15VDC nominal

Communication Interface USB Cable Included

Data Storage Removable Media Card

Shunt Calibration Across bridge completion resistors controlled

by software When Gage Factor=200

120Ω350Ω1000Ω

Analog Output Value 0 to 25V max

Ranges plusmn320 microε plusmn3200 microε plusmn32000 microε

Error 05 output voltage +5mV

Max Error 14 output voltage + 20mV

Update rate 480 samplessec

Output Load 2000Ω

Power Battery Two Alkaline D cells

Battery life 400 hours typ

USB 5V 100mA

Operational Environment Temperature 0-50

Humidity Up to 90 Non-condensing

Case Aluminum Alloy

Size and Weight 228times152times152(mm) 20(kg)

Table 3-2 Vishay Micro-Measurements Model P3 Strain Indicator and Recorder Specs

45

323 Strain Gauge

The strain gaugersquos main basic principle is to use a resistancersquos characteristics to measure the strain

The inside connections of the strain indicator are shown in figure 3-5

Fig 3-5 Inner Connections

As shown above this is a quarter-bridge connection We connect equal-length 3 wires to the 2

connections allowed by the strain gauge wire 1 and 3 can be used to cancel out the effects of temperature

to the resistance and because of the addition of wires 1 and 3 wire 2 can directly measure the experiment

results from the strain gauge and therefore the strain developed with no influence of temperature

If there were no two measuring leads then the relations will be

R 4 =R g +2R L

Where Rg is the Strain Gauge Value and RL is the wire resistance then

4

4

R

R=

Lg

g

RR

R

2

=

gL

gg

RR

RR

21

amp

4

4

R

R=

g

g

R

R(1- L)

Where L is the Signal Loss Factor and so

L =gL

gL

RR

RR

21

2

g

L

R

2R if

g

L

R

2Rltlt1

46

(Actual Value R g =120R L =08g

L

R

2Ris always much smaller than 1)

R 4 =R g +2R LR 2 =R 3 =rR gR 1 =R g 32 RR =0

V 0 =V 2)1( r

r

(

4

4

R

R-

1

1

R

R)

The first term describes loss attenuation effects second term describes loss of balancing capabilities

effects

V 0 =V 2)1( r

r

[

)2

(Lg

g

RR

R

+

T

Lg

g

RR

R

)

2( + T

Lg

L

RR

R

)

2

2( -(

g

g

R

R) T ]

The first term describes loss attenuation effects and loss of balancing capabilities effects the second

third and fourth terms describe the temperature effects on the wire

For the three-wire method we have

L =gL

gL

RR

RR

1

g

L

R

R if

g

L

R

Rltlt1

V 0 =V 2)1( r

r

[

)(Lg

g

RR

R

+

T

Lg

g

RR

R

)( + T

Lg

L

RR

R

)

2( -

T

Lg

g

RR

R

)( - T

Lg

L

RR

R

)

2( ]

V 0 = V2)1( r

r

)(

Lg

g

RR

R

In the last four terms inside parenthesis we can see the effects of temperature being cancelled out and the

effect on first term is not great so this is the reason why in our research we use three wires

47

324 Specimen Measurements

The tensile specimens used in this research are compliant of ASTM E8 Tensile parameters as shown

in figure 3-6

Fig 3-6 Tensile Specimen

Diameter

D(mm)

Gauge

Length

G(mm)

Smallest

Arc

Radius

R(mm)

Shortest

Area

A(mm)

Total

Length

L(mm)

Clamping

Area

Length

B(mm)

Clamping

Area

Diameter

C(mm)

Bar 125 02 625 01 gt10 gt75 ~ 145 ~ 35 20

Table 3-3 Specifications for Round Bar

33 Experiment Procedure

1 Attaching the Strain Gauge to the Tensile Specimen

(1) Prepare 1 ASTM E8 compliant tensile specimen round bar as shown in figure 3-7

(2) Prepare Strain Gauge as those described in table 3-4

(3) Prepare other consumables and adhesive agent such as epoxy adhesive or

cyanoacrylate adhesive as shown in figure 3-8

48

Fig 3-7 Actual Tensile Specimen

Fig 3-8 Other Materials Used (Such as Alcohol gauze transparent tape adhesive)

Gage Type

EA-06-120LZ-120E

Resistance in ohms at 24∘C

1200plusmn03

Gage Factor at 24∘C

2075plusmn05

Transverse Sensitivity at 24∘C

(+07plusmn02)

Table 3-4 Specifications for Strain Gauge

2 Attaching Strain Gauge

As shown in following figures we shall explain the attachment of the strain gauge

(1) Use sand paper and a rasp to clean thoroughly the surface where the strain gauge will be

attached to

49

(a)

(2) Use alcohol to wash the surface where the strain gauge will be attached and use gauze to rub

it off

(b)

(3) Find a clean surface and clean it with alcohol and gauze

(c)

(4) Place the strain gauge in the clean surface Use a piece of transparent tape on top of the strain

gauge after securely placed rip it off the surface carefully

50

(d)

(5) Use a piece of white paper to mark the place where the strain gauge will be attached and in

this way we can make sure that the strain gauge will be placed as horizontally and vertically

correct as possible

(e)

(6) In the place where we had our mark place the strain gauge

(f)

(7) Carefully lift one side of the tape and apply some of the adhesive agent to both the strain

gauge and specimenrsquos surface

(g)

51

(8) We need to make sure that the gauge and the specimen will be firmly attached so we gently

apply pressure with our thumb

(h)

(9) After the adhesive is fully dry we can carefully rip off the tape

(i)

(10) We need to do the whole process twice one for the horizontally placed strain gauge and one

for the vertically placed strain gauge

52

(j)

(11) We now proceed to solder the wires to the strain gauge

(k)

(12) After soldering we use a Volt Multimeter to measure that there is no contact between wires

If there is none then the specimen is ready for testing

(l)

(13) We now need to measure a 5cm distance and mark it to check and compare the elongation

before and after the tensile testing

(m)

53

Fig 3-9 Specimen-Strain Gauge Process

3 Tensile Test

(1) Enter the computer application that controls the tensile testing machine

(2) Turn on the tensile testing machine main switch

(3) Adjust the hydraulic pump to go back to its original position

(4) Bring the lowering motor down to a distance enough so as to attach the tensile specimen to the

system open the clamps and secure the specimen

(a)

(5) Connect all the necessary wires to the strain indicator equipment

54

(b)

(6) Start the ascending motor and wait for the expansion

(c)

Fig 3-10 Specimen-Tensile Testing Process

4 Start the Test

(1) Enter the software application and enter some variables needed for the experiment in the

specific screen

(2) Go back to the main screen and press the [測試] (measure) button to start the test and auto

recording in the software

(3) After the specimen breaks the mechanical device will automatically stop and ask the user to

enter the total displacement We take out the specimen from the testing machine and adjust the

machinersquos position back to its original position

(4) Save the results information

(5) Record the results from the strain indicator

34 Results

From this experiment we can get the Poissonrsquos Ratio Youngrsquos Modulus and Yield Strength etc and

because of the slippage phenomenon in the clamp at the moment of the test then the Elastic Limit will

display some yield phenomena So omit any undesirable results we just take the Yield portion of the

results as reference

In the process of the experiment the most important part to attend to is the attaching of the strain

gauge because the gaugersquos purpose is to measure the strain developed during the test and this strain

might be very small If the gaugersquos angle change during the test ie is not well attached this will affect

the accuracy of the measurements of Poissonrsquos ratio and Youngrsquos modulus

55

The materials provided by the manufacturer are SUM 23 and SUM 43 steel round bars and these two

types of materials have been through different heat treatment processes so they can be sub-divided

further into untreated material heat-treated material and black surface heat treated material for the two

materials with heat treatment the treatment process and finished are different In the end we only have

the mechanical properties that were calculated after our research of these materials

All of the specifications are identical to those shown in figure 3-6

341 SUM 23

Fig 3-11 SUM 23 Untreated Material

Number 7 10

Hardness(HRB) 74 75

Yield Stress (MPa) 448 440

Tensile Strength (MPa) 544 560

Poissonrsquos Ratio 029 027

Youngrsquos Modulus (GPa) 203 210

Cut-off Area Shrinking () 42 41

Elongation () 1125 1011

Table 3-5 Mechanical Properties of SUM 23 Untreated

56

Stress-Strain Diagram

(a)

(b)

57

Fig 3-12 Stress-Strain Diagrams for (a) 7 Round Bar and (b) 10 Round Bar

Cut-Off Area

(a)

(b)

Fig 3-13 Cut-Off Area of (a) 7 Round Bar and (b) 10 Round Bar

58

SUM 23 Nickel Round Bar

Fig 3-14 SUM 23 Nickel Material

Number 1 2 3 4

Hardness(HRB) 48 50 49 48

Yield Stress (MPa) 370 370 380 400

Tensile Strength (MPa) 455 451 450 450

Poissonrsquos Ratio 028 046 029 026

Youngrsquos Modulus (GPa) 243 303 246 206

Cut-off Area Shrinking () 803 803 726 601

Elongation () 566 65 602 647

Table 3-6 Mechanical Properties of SUM 23 Nickel

59

Stress-Strain Diagram

(a)

60

(b)

(c)

(d)

61

Fig 3-15 Stress-Strain Diagrams for (a) 1 Round Bar (b) 2 Round Bar (c) 3 Round Bar and (d)

4 Round Bar

Cut-Off Area

(a)

(b)

62

(c)

(d)

Fig 3-16 Cut-Off Area of (a) 1 Round Bar (b) 2 Round Bar (c) 3 Round Bar and (d) 4 Round

Bar

63

SUM 23 Black Surface Round Bar

Fig 3-17 SUM 23 Black Surface Material

Number 1 2 3

Hardness(HRB) 51 50 51

Yield Stress (MPa) 378 371 369

Tensile Strength (MPa) 467 465 464

Poissonrsquos Ratio 03 016 04

Youngrsquos Modulus (GPa) 215 266 266

Cut-off Area Shrinking () 986 94 848

Elongation () 748 805 761

Table 3-7 Mechanical Properties of SUM 23 Black Surface Material

64

Stress-Strain Diagram

(a)

(b)

65

(c)

Fig 3-18 Stress-Strain Diagrams for (a) 1 Round Bar 2 Round Bar and (c) 3 Round Bar

Cut-Off Surface

(a)

66

(b)

(c)

Fig 3-19 Cut-Off Surface of (a) 1 Round Bar 2 Round Bar and (c) 3 Round Bar

67

342 SUM 43

Fig 3-20 Untreated SUM 43 Untreated Material

Number 1 5

Hardness(HRB) 76 75

Yield Stress (MPa) 572 594

Tensile Strength (MPa) 743 785

Poissonrsquos Ratio 027 029

Youngrsquos Modulus (GPa) 200 202

Cut-off Area Shrinking () 338 2944

Elongation () 857 894

Table 3-8 Mechanical Properties of SUM 43 Untreated

68

Stress-Strain Diagrams

(a)

(b)

Fig 3-21 Stress-Strain Diagrams for SUM 43 (a) 1 Round Bar and (b) 5 Round Bar

69

Cut-Off Area

(a)

(b)

Fig 3-22 Cut-Off Area of SUM 43 (a) 1 Round Bar and (b) 5 Round Bar

70

SUM 43 Nickel Round Bar

Fig 3-23 SUM 43 Nickel Material

Number 4 5

Hardness(HRB) 51 50

Yield Stress (MPa) 1580 1544

Tensile Strength (MPa) 1639 1625

Poissonrsquos Ratio 03 028

Youngrsquos Modulus (GPa) 194 201

Cut-off Area Shrinking () 1697 137

Elongation () 376 265

Table 3-9 Mechanical Properties of SUM 43 Nickel

71

Stress-Strain Diagrams

(a)

(b)

Fig 3-24 Stress-Strain Diagrams for (a) 4 Round Bar and (b) 5 Round Bar

72

Cut-Off Area

(a)

(b)

Fig 3-25 Cut-Off Area of (a) 4 Round Bar and (b) 5 Round Bar

73

SUM 43 Black Surface Material

Fig 3-26 SUM 43 Black Surface Material

Number 3 5

Hardness(HRB) 56 56

Yield Stress (MPa) 1416 1361

Tensile Strength (MPa) 1591 1402

Poissonrsquos Ratio 029 031

Youngrsquos Modulus (GPa) 200 202

Cut-off Area Shrinking () 139 124

Elongation () 24 24

Table 3-10 Mechanical Properties of SUM 43 Black Surface Material

74

Stress-Strain Diagrams

0 2 4 6 8 10 12 14

-200

0

200

400

600

800

1000

1200

1400

1600

1800

應力 (MPa)

應變()

(a)

0 2 4 6 8 10

-200

0

200

400

600

800

1000

1200

1400

1600

應力

(MPa)

位移 ()

(b)

Fig 3-27 Stress-Strain Diagrams for (a) 3 Round Bar and (b) 5 Round Bar

(Note These curves were formulated using Visual Solutions Inc VisSim Software)

75

Cut-Off Area

(a)

(b)

Fig 3-28 Cut-Off Area of (a) 3 Round Bar and (b) 5 Round Bar

76

The force value (N) was retrieved from the Universal Testing Machine

The Poissonrsquos Ratio (ε) is calculated as

ε =

the values for the Poissonrsquos Ratio are in average around 0297

The Youngrsquos Modulus (E) is calculated as

E =

Where

Stress =

Cross-sectional Area =

where D is the Diameter

The value for D was in average around 1258 mm

The values shown by the computer because there is Slippage phenomena between the Clamp and the

specimen will not be taken into consideration for the elongation strain and Youngrsquos modulus and we will

refer to the values that we have meticulously calculated

77

Chapter 4 AR COATING IN DEPTH

41 Experimentrsquos Purpose and Principles

By means of a vacuum chamber and several other instruments we intend to apply Anti-Reflective

Coating using deposition process to a laser diode and in this way reduce its refraction so as to make it

lose less light in the process of amplification and we can control certain wavelengths we want produced

for certain desired applications in our case we are attempting to re-create a Bose-Einstein Condensate

An optimal BEC apparatus is shown in figure 4-1

Fig 4-1 BEC Apparatus

The main point of this experiment is to build a vacuum chamber system attach all the instrumentation

needed (Vacuum pump deposition meter and voltmeter) and use it to apply AR coating to a laser diode

After we have accomplished the AR coating other team will be in charge of designing the BEC apparatus

and use the results of our research

78

42 Experimentrsquos Equipment

421 Vacuum Chamber

For this research we designed a vacuum chamber whose main body is shown in figure 4-2 Its

dimensions are

Width 240 mm

Length 240 mm

Height 200 mm

Outer Diameter 4 in

Inner Diameter 15 in

Fig 4-2 Vacuum Chamber Main Body

The chamber is made up of 6 pass ways pass way A is the connection with the Laser Deposition

Equipment pass way B is the connection with the Turbo Pump and pass way C is for the connection with

the Deposition Source

A

C

B

79

Pass way C is for the deposition source as mentioned above This is a system where a thermal

resistance is heated by passing a high current through it which heats up a filament boat (made of tungsten)

where the material to be evaporated is place We control the temperature as such that the material will

evaporate and the heat will not cause the filament boat to crack

Because P = Isup2 R (where P is power I is current and R is resistance) to avoid the current to flow

where it is not desired we decided that the material for the Thermocouple shown in figure 4-3 should be

Copper ᴓ 63 mm We choose it that way because Copper has very good heat dissipation characteristics

and the resistance value is low It can reduce the value of the current enough to make the thermocouple to

create heat

Fig 4-3 Thermocouple

To the thermocouple we attach the tungsten filament boat We need to take notice of materials to be

used in this design because when using high current the tungsten filament boar will heat up and so the

material must be able to keep up with the heating potential of tungsten and has a low coefficient of heat

dissipation to avoid the tungsten to fail when heating up and therefore not evaporating Considering all

this we decide to use Stainless Steel

Because this clamp will be assembled inside the chamber after many revisions it was determined it

will have the shape shown in figure 4-4

Fig 4-4 Filament Boat Clamp Design

80

For the tungsten filament boat we bought the product from a distributor The dimensions are

Length 100 mm

Width 10 mm

Height 1 mm

Our thermocouple is 15 in but the pass way C is 4 in so we need to attach a Flange that connects

15in to 4in Because these specifications are quite difficult to achieve by Milling we had to use

electrical wire cutting

For the laser clamping system where the laser that is going to be AR coated will be placed will be

connected to pass way A the assembly is shown in figure 4-5 below

Fig 4-5 Cover Assembly

For this design we used an O-ring instead of a gasket so as to save time The design of the assembly

where the laser will be placed is shown in figure 4-6

Fig 4-6 Upper Cover Inner Assembly

D

E

F

81

Point D is the plate in the assembly where the laser diode will be fixed Because of the easy

processing we decide to use Aluminum and it is screwed to the top cover Point E is the connection for

the Quartz crystal resonator and it is designed in the same as point F in this way the results of the quartz

microbalance system will be more accurate in real time Point F is the final resting place for the laser

diode We use a Thor Labs Base with dimensions of ᴓ 9mm and ᴓ 56mm for two different size laser

diodes It just needs to be plugged in for easy installation

From figure 4-6 we know that the system needs signal system connections and because of the

change in temperature inside the chamber this could affect the functioning of the quartz microbalance so

we also need to install water tubes for cooling This is shown in figure 4-7 below

Fig 4-7 Diagram of Upper Cover Connections

In figure 4-8 we show the Feed through connections and their functions

Fig 4-8 Feed through Diagram

82

1 SQM-160 wire 5 Laser Connection 1 (Vin)

2 SQM-160 (G) 6 Laser Connection 2 (G)

3 K-Type-1 7 Laser Connection 3 (PD)

4 K-Type-2 8 Not In Use

The fully assembled chamber is shown in figure 4-9

Fig 4-9 Fully Assembled Chamber

422 Quartz Crystal Microbalance

For measuring the deposition on our target for coating we used the Inficon SQM-160 RateThickness

Monitor It is an easy to use instrument for measuring many types of thin-film coatings as shown in

figure 4-10

(a) Front Panel (b) Back Panel

Fig 4-10 Inficon SQM-160

83

Table 4-1 shows the technical specifications for this equipment

Number of sensors 2 Standard 4 additional optional

Sensor Frequency Range 40 MHz ~ 60 MHz

Reference Frequency Accuracy 002

Thickness Display Resolution 1 Aring

Thickness Resolution 015 Aring (Std) 0037 Aring (Hi Res)

Density of Stored Films 05-9999 gmcc

Tooling 10-399

Z-Factor 010-1000

Final Thickness 0000-9999k Aring

Measurement Period 15 to 2 sec

Simulation Mode Yes

Frequency Mode Yes

Rate Resolution 011 Arings

Dual Crystal Yes

Etch Mode Yes

Crystal Tooling 10-399

Crystal Fail Min Max 40 to 60 MHz 41 to 61 MHz

Power 100-120 200-240~plusmn10 nominal 20W

Operation Environment 0degC ~ 50degC

0 ~ 80 RH non-condensing

0 ~ 2000 meters

Class 1 Equipment

Pollution Degree 2

Rack Dimensions 885mm x 2127mm x 1969mm

Weight 27 kg

Table 4-1 Inficon SQM-160 RateThickness Monitor Specs

84

To the SQM-160 we need to connect an Oscillator We use the Sigma Instruments Remote Oscillator

Ser No 2 268 as shown in figure 4-11

Fig 4-11 Sigma Instruments Remote Oscillator

The connections diagram is shown in figure 4-12

Fig 4-12 SQM-160 Connections Diagram

85

423 Turbo Pump

For our experiments we used the Pfeiffer TCP 015 Electronic Drive Unit shown below in figure 4-13

Table 4-2 shows the technical specifications for this equipment

(a) Front Panel (b) Back Panel

Fig 4-13 Pfeiffer TCP 015 Electronic Drive

Connection Voltage (100V) 90-112

Mains Frequency 5060 Hz

Start-up Current 22 A

Nominal Frequency 1500 Hz

Rotation Speed 10V = 1500Hz plusmn2

Analog Output Current 10 V = 25 A plusmn 5

Rotation Speed Switchpoint 750 Hz

Works Setting 8 min

Permissible Ambient Temperature 0degC ~ 40degC

Dimensions Front Panel 1285mm x 1063mm

Insertion Length 227mm

Weight 27 Kg

Table 4-2 Pfeiffer TCP 015 Electronic Drive Specs

86

The connections diagram is shown in figure 4-14

Fig 4-14Connections Diagram for Pfeiffer TCP 015

To measure the pressure inside the chamber we use the Granville Phillips 375 Convectron Vacuum

Pressure Controller shown in figure 4-15

(a) Front Panel (b) Back Panel

Fig 4-15 Granville Phillips 375 Convectron

87

Its dimensions are shown in figure 4-16

Fig 4-16 Dimensions of Convectron

Table 4-3 shows the technical specifications for this equipment

Table 4-3 Granville Phillips 375 Convectron Vacuum Pressure Controller Specs

88

424 Multimeter

For our experiment we used the Keithley 2000 Digital Multimeter as shown in figure 4-17

(a) Front Panel (b) Back Panel

Fig 4-17 Keithley Model 2000 6-12-Digit Digital Multimeter

Its technical specifications are shown in table 4-4

Table 4-4 Keithley Model 2000 6-12-Digit Digital Multimeter Specs

89

43 Experiment Procedure

1 Connecting together the equipment and the chamber

(1) We first connect the resonator to the thickness monitor and connect the other side to the

chamber

(2) We now connect the flexible tubes to the turbo pump on one side and to the chamber on the

other

(3) We need to check that tubes are tightly connected to avoid any leaks in the vacuum pumping

process which will not allow us to get to our goal of Torr As shown in figure 4-18

(4) Connect the convectron to the system as shown in figure 4-19

Fig 4-18 checking for leaks using alcohol

Fig 4-19 Convectron attached to System

90

(5) Attach the clamps of the Multimeter to the bottom of the chamber as shown in figure 4-20

(6) Place the Quartz crystal in place

(7) Close tight vacuum chamber

(8) Connect all electrical appliances to power source

Fig 4-20 Multimeter Connections

2 Starting up the System

(1) We turn on all the devices as such Check all systems are ready to function Reset all values

that might be left over from previous tests

(2) Start the thickness monitor and set all values for this experiment In our case we got to testing

the system but not actual coating So we used the simulation mode of the thickness monitor as

shown in figure 4-21

Fig 4-21 Simulation Mode

91

(3) Start the turbo pump Make sure the lid on the vacuum chamber is tightly closed

(4) Start convectron and record initial pressure

(5) Start Multimeter and record initial current

3 Coating Process

(1) If we have the deposition material inside the filament boat the power source for the high

current must be started as well

(2) Record all initial values for thickness current pressure

(3) For an ideal experiment we need a thickness of around 101 nm a pressure of Torr and

a current of 300 A

44 Results

From previous experiments we have shown that we can turn a LED into a laser by means of AR

Coating In figure 4-22 shown below we can compare the actual results of a Diode before and after AR

coating From the blue line we can see that when the diode is at a current of 15mA its light will change

from LED to laser and if we look at the red line its critical current is around 30 to 35 mA

Fig 4-22 AR Coating Comparison for Laser Diodes

This means that the light emitted is not as strong as if the diode had been coated because inside the

chamber there must be some excitation first so the reflectivity of both sides inside the diode must be high

So because of the coating in one of the sides we have opened a door and let the light come out so the

critical current is risen as such and will be higher value than that of before the coating

92

In the following figures we can see the difference between before and after coating in a material The

thickness is around 1016 nm for this material

Fig 4-23 Before Coating

Fig 4-24 After Coating

93

Chapter 5 CONCLUSIONS AND RECOMMENDATIONS

51 Conclusions

For the first part of this independent study taking into consideration the data that came out of our

research and that sent by the provider we can say

1 SUM 23 after heat treatment will unexpectedly develop cracking in the middle of the tensile

testing process and suddenly break

2 Itrsquos possible that in the process of heat treatment to the SUM 23 material the treatment was not

uniform and this will create a pre-loaded moment force on one side that pushes on the other side

of the specimen resulting in material deformation

3 In the process of attaching the strain gauges to the materials it is very easy to make errors due to

poor adhesion or sudden removal in the tensile testing process

For our second part of the independent study the following can be made

1 At the beginning of this independent study we had no idea what Bose-Einstein Condensate was

or what was its purpose After much literature we finally comprehended the basic principles to

put into practice for our research

2 Our systemrsquos basic working principles and equipmentrsquos complexity are a little difficult to grasp

but hopefully we were able to understand enough of it

3 Theoretically from relation between the power and current we can know the advantages and

disadvantages of AR Coating

4 We were able to assemble the system and run test on its functions Even though we were able to

do this there is still much more work left to do with this system

52 Recommendations

For the Tensile Testing the following can be said

1 Ask the provider to check on the process of heat treatment on the SUM 23 material and give

them the information we have gathered through our test so they can correct for the mechanical

properties found if any change is needed

2 To avoid the problem of the inaccuracy of the poor adhesion of strain gauges we can attach

multiple strain gauges to the same one specimen so as to correlate data and improve our results

For the AR Coating the following can be said

1 We need to make sure that there are no physical defects on the main body of the chamber so as to

achieve maximum efficiency in the vacuum process If there was then the vacuum will arrive to

certain point and then start to decrease

2 It would be preferable to add some sort of visual aid that will allow the user to check the inside of

the chamber without actually opening it This will help us determine at what times we should

manipulate the current to better evaporate the substrate

94

REFERENCES

[1] A L Window Strain Gauge Technology Elsevier Applied Science London and New York 2nd

Edition 1992

[2] CC Perry and HR Lissner Strain Gauge Primer McGraw-Hill Book Co Inc New York 1955

[3] James W Dally William F Riley McGraw-Hill 1978

[4] University of Colorado Boulder BEC - What is it and where did the idea come from

httpwwwcoloradoeduphysics2000becwhat_is_ithtml

[5] Ultraslow Light amp Bose-Einstein Condensates Two-way Control with Coherent Light amp Atom

Fields Harvard Hau Lab Dr Lene Vestergaard Hau Optics amp Photonics News 16 1995

[6] The Art of Taming Light Ultra-slow and Stopped Light Harvard Hau Lab Dr Lene

Vestergaard Hau Europhysics News 2004

[7] Nonlinear Optics Shocking Superfluids Harvard Hau Lab Dr Lene Vestergaard Hau Nature

Physics 2007

[8] Model P3 Strain Indicator and Recorder Instruction Manual Vishay Micro-Measurements 2005

[9] Granville-Phillips Series 375 Convectron Vacuum Gauge Controller Instruction Manual Brooks

Automation 2008

[10] Effect of Film Thickness on the Validity of the Sauerbrey Equation for Hydrated Polyelectrolyte

Films Vogt Lin Wu White 2004

[11] Quartz Crystal Microbalance Study of DNA Immobilization and Hybridization for DNA Sensor

Development Chang Zhao 2008

[12] Installation of Strain Gages with SR-4 PrecoatAdhesive Vishay Micro-Measurements 2005

[13] Strain Gauge Measurement ndash A Tutorial National Instruments 1998

[14] Correlation between Vickers Hardness Number and Yield Stress of Cold-Formed Products

Yavuz Tekkaya

[15] httpsenwikipediaorg

Page 5: PC Hinge Materials Testing and AR Laser Diode Coating

5

TABLE OF CONTENTS

ABSTRACThelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 2

ACKNOWLEDGEMENThelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 4

TABLE OF CONTENTShelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 5

LIST OF TABLEShelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 7

LIST OF FIGUREShelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 8

CHAPTER 1 Introductionhelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 10

11 Motivation and Backgroundhelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 10

12 Research Objectivehelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 11

13 Methodologyhelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 13

14 Organization of the Thesishelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 13

CHAPTER 2 Basic Principleshelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 14

21 Tensile Testinghelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 14

211 Youngrsquos Modulushelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 14

212 Yield Strength and Yield Pointhelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 15

213 Ultimate Tensile Strength and Breaking Strengthhelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 16

214 Poissonrsquos Ratiohelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 16

215 Strain Gauge Basic Principleshelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 16

22 Hardness Test Basic Principleshelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 18

221 Brinell Scale BHNhelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 18

222 Rockwell Scale HRhelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 19

223Vickers Hardness Test HVhelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 21

23 AR Coatinghelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 22

231 Bose-Einstein Condensatehelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 22

232 AR Coating Basic Principleshelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 25

233 Laser Diode Basic Principleshelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 28

234 Quartz Microbalance Systemhelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 29

235 Vacuum Chamber Systemhelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 38

CHAPTER 3 Tensile Testing in depthhelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 41

31 Experimentrsquos Purpose and Principleshelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 41

32 Experimentrsquos Equipmenthelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 41

321 Universal Testing Machinehelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 41

322 Strain Measurement Equipmenthelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 43

6

323 Strain Gaugehelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 45

324 Specimen Measurementshelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 47

33 Experiment Procedurehelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 47

34 Resultshelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 54

341 SUM 23helliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 55

342 SUM 43helliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 67

CHAPTER 4 AR Coating in depthhelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 77

41 Experimentrsquos Purpose and Principleshelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 77

42 Experimentrsquos Equipmenthelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 78

421 Vacuum Chamberhelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 78

422 Quartz Microbalancehelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 82

423 Turbo Pumphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 85

423 Multimeterhelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 88

43 Experiment Procedurehelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 89

44 Resultshelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 91

CHAPTER 5 Conclusions and Recommendationshelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 93

51 Conclusionshelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 93

52 Recommendationshelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 93

REFERENCEShelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 94

7

LIST OF TABLES

Table 2-1 Rockwell Hardness Test Scalehelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 20

Table 2-2 Z-Ratios for Different Materialshelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 33

Table 2-3 Classifications of Vacuumhelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 39

Table 3-1 Chun Yen Testing Machine Specshelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 42

Table 3-2 Vishay Micro-Measurements Model P3 Strain Indicator and Recorder Specshelliphelliphelliphelliphelliphellip 44

Table 3-3 Specifications for Round Barhelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 47

Table 3-4 Specifications for Strain Gaugehelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 48

Table 3-5 Mechanical Properties of SUM 23 Untreatedhelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 55

Table 3-6 Mechanical Properties of SUM 23 Nickelhelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 58

Table 3-7 Mechanical Properties of SUM23 Black Surface Materialhelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 63

Table 3-8 Mechanical Properties of SUM 43 Untreatedhelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 67

Table 3-9 Mechanical Properties of SUM 43 Nickelhelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 70

Table 3-10 Mechanical Properties of SUM 43 Black Surface Materialhelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 73

Table 4-1 Inficon SQM-160 RateThickness Monitor Specshelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 83

Table 4-2 Pfeiffer TCP 015 Electronic Drive Specshelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 85

Table 4-3 Granville Phillips 375 Convectron Vacuum Pressure Controller Specshelliphelliphelliphelliphelliphelliphelliphelliphellip 87

Table 4-4 Keithley Model 2000 6-12-Digit Digital Multimeter Specshelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 88

8

LIST OF FIGURES

Fig 1-1 Notebook Computer Hingehelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 11

Fig 1-2 Basic Structure of Laserhelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 11

Fig 1-3 Comparison between LED and Laser Diodehelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 12

Fig 1-4 External Cavity Designhelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 12

Fig 2-1 Stress-Strain Curvehelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 14

Fig 2-2 Stress-Strain Curve Comparison on Metalshelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 15

Fig 2-3 Basic Structure of Strain Gaugehelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 17

Fig 2-4 Strain Gauge Attached to Wheatstone Bridgehelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 18

Fig 2-5 Brinell Indentationhelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 18

Fig 2-6 Brinell Hardness Testerhelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 18

Fig 2-7 Rockwell Indentationhelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 19

Fig 2-8 Rockwell Hardness Testerhelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 19

Fig 2-9 Vickers Indentationhelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 22

Fig 2-10 Vickers Hardness Testerhelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 22

Fig 2-11 Bose-Einstein Condensate at different scaleshelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 23

Fig 2-12 Super Conductorhelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 24

Fig 2-13 Simple Model for Light in Glass Mediumhelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 25

Fig 2-14 Simple Model for Light in Glass Medium after AR Coatinghelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 26

Fig 2-15 Light Passing through AR Coating and Glasshelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 27

Fig 2-16 Lens without and with AR Coatinghelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 27

Fig 2-17 Laser Diodehelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 28

Fig 2-18 Tunable Laser Basic Configurationhelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 28

Fig 2-19 Light Spectrumhelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 29

Fig 2-20 Front and Back Panel of SQM-160helliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 29

Fig 2-21 QCM Crystalshelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 31

Fig 2-22 SQM-160 Oscillatorhelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 31

Fig 2-23 Oscillator Circuithelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 32

Fig 2-24 Vacuum Evaporation Systemhelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 39

Fig 2-25 Turbo Pumphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 39

Fig 2-26 Control and Measurement Equipmenthelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 40

Fig 2-27 Complete Systemhelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 40

Fig 3-1 Universal Testing Machinehelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 41

Fig 3-2 Diagram for System Connectionshelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 42

Fig 3-3 Input Connections for Strain Gaugehelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 43

Fig 3-4 Vishay Micro-Measurements Model P3 Strain Indicator and Recorderhelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 43

Fig 3-5 Inner Connectionshelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 45

Fig 3-6 Tensile Specimenhelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 47

Fig 3-7 Actual Tensile Specimenhelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip47

Fig 3-8 Other Materials Usedhelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 48

Fig 3-9 Specimen-Strain Gauge Processhelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 49

Fig 3-10 Specimen-Tensile Testing Processhelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 53

9

Fig 3-11 SUM 23 Untreated Materialhelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 55

Fig 3-12 Stress-Strain Diagrams for 7 and 10 Round Barhelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 56

Fig 3-13 Cut-Off Area of 7 and 10 Round Barhelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 57

Fig 3-14 SUM 23 Nickel Materialhelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 58

Fig 3-15 Stress-Strain Diagrams for 1 2 3 and 4 Round Barhelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip60

Fig 3-16 Cut-Off Area of 1 2 3 and 4 Round Barhelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 62

Fig 3-17 SUM 23 Black Surface Materialhelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 63

Fig 3-18 Stress-Strain Diagrams for 1 2 and 3 Round Barhelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 65

Fig 3-19 Cut-Off Area of 1 2 and 3 Round Barhelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 66

Fig 3-20 SUM 43 Untreated Materialhelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip67

Fig 3-21 Stress-Strain Diagrams for 1 and 5 Round Barhelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 68

Fig 3-22 Cut-Off Area of 1 and 5 Round Barhelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 69

Fig 3-23 SUM 43 Nickel Materialhelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 70

Fig 3-24 Stress-Strain Diagrams for 4 and 5 Round Barhelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 71

Fig 3-25 Cut-Off Area of 4 and 5 Round Barhelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 72

Fig 3-26 SUM 43 Black Surface Materialhelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 73

Fig 3-27 Stress-Strain Diagrams for 3 and 5 Round Barhelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 74

Fig 3-28 Cut-Off Area of 3 and 5 Round Barhelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 75

Fig 4-1 BEC Apparatushelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 77

Fig 4-2 Vacuum Chamber Main Bodyhelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 78

Fig 4-3 Thermocouplehelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip79

Fig 4-4 Filament Boat Clamp Designhelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 79

Fig 4-5 Cover Assemblyhelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 80

Fig 4-6 Upper Cover Inner Assemblyhelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 80

Fig 4-7 Diagram of Upper Cover Connectionshelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 81

Fig 4-8 Feed Through Diagramhelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 81

Fig 4-9 Fully Assembled Chamberhelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 82

Fig 4-10 Inficon SQM-160helliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 82

Fig 4-11 Sigma Instruments Remote Oscillatorhelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 84

Fig 4-12 SQM-160 Connections Diagramhelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 84

Fig 4-13 Pfeiffer TCP 015 Electronic Drivehelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 85

Fig 4-14 Connections Diagram for Pfeiffer TCP 015helliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 86

Fig 4-15 Granville Phillips 375 Convectronhelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 86

Fig 4-16 Dimensions of Convectronhelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 87

Fig 4-17 Keithley Model 2000 6-12-Digit Digital Multimeterhelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 88

Fig 4-18 Checking for Leaks Using Alcoholhelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 89

Fig 4-19 Convectron Attached to Systemhelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 89

Fig 4-20 Multimeter Connectionshelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 90

Fig 4-21 Simulation Modehelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 90

Fig 4-22 AR Coating Comparison for Laser Diodeshelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 91

Fig 4-23 Before AR Coatinghelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 92

Fig 4-24 After AR Coatinghelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 92

10

Chapter 1 INTRODUCTION

11 Motivation and Background

In response that new generation computers are gradually reducing their size the diameter of

the structures of the hinges used by NB computers must also follow but the hinge strength may

also become smaller due to the reduction of diameter and result in the phenomenon of

insufficient strength In addition the disk-type spring that is source of the torque may also be

insufficient due to the narrowing of the structure Therefore it is necessary to direct a structural

analysis of the hinge for the existing laptops so that we can identify the stress concentration

point The stress concentration point is usually the point where material damage behavior is

encountered the easiest and if we can find the point where breaking occurs most often we can

improve the design of the existing structure to enhance the strength of the hinge structure

Second the structure of the hinge is too complicated the traditional mechanics of materials

analysis methods and formulas are no longer suitable for analysis of a wide arrange of hinge

design In recent years finite element analysis methods have been widely applied in various

fields such as electronics machinery aviation and so on

Therefore to meet the need of the industry and with the purpose of reducing design time

how to design a notebook computer hinge without compromising mechanical stability and

materialrsquos hardness which will operate equally under equal conditions In other words be able to

meet the needs of the size decreasing NB computers market as the needs for this kind of

accessories will increase in the near future If we take into consideration the traditional ways of

design we seek to reduce the costs of use of machinery and molding by applying Finite Element

Analysis methods to our study and also increase the flexibility of designing methods

The second project was brought in by Prof Chuang and it is to help in the further research of

the Bose-Einstein condensate This is a state of matter of a dilute gas weakly interacting bosons

(subatomic particles that obey the Bose-Einstein statistics) confined in an external potential and

cooled down to temperatures very near absolute zero (0 K or -27315deg C) Under these conditions

a large number of bosons occupy the lowest quantum state of the external potential at which

point quantum effects become apparent at macroscopic scale This state of matter was predicted

by Satyendra Nath Bose and Albert Einstein in 1924~1925 Then 70 years later the 1st gaseous

condensate was produced by Eric Cornell and Carl Wieman in 1995 at the University of

Colorado (Boulder) NIST-JILA lab and because of this along with Wolfgang Ketterle of MIT

they received the 2001 Nobel Prize in Physics

11

We wish to investigate the properties of Anti Reflecting Coating on laser diodes Hopefully

we will be able to achieve the desired effect of reducing the surface reflection coefficient and

find applications for it

12 Research Objective

We wish to analyze the normal composition of the notebook computerrsquos hinge at which

point in the assembly is clearly the weakest and at this time in the assembly the strength and

durability are influenced The main point is to see if we can affect the normal operation and work

life

The objective of this thesis is to present the results of the material properties under tensile

testing find the mechanical properties and after using finite element analysis determine what

material is the best for our purposes

Fig 1-1 Notebook Computer Hinge

For our second research we wish to produce and analyze laser diodes with anti-reflective

coating and test its properties and applications

When semi-conductor laser has been submitted to current it will produce resonance inside it

and light will be stimulated to come out Please refer to figure 1-2 for the basic structure of a

laser

Fig 1-2 Basic Structure of a Laser

1 Gain Medium

2 Laser Pumping Energy

3 High Reflector

4 Output Coupler

5 Laser Beam

12

But when the laser diode generates light but the laser diode canrsquot produce light on itself it

must wait for the current to be higher than certain value which is called the critical current Until

the light goes over this threshold then it is considered laser light if not it is just considered as a

common LED light source Please refer to figure 1-3

Fig 1-3 Comparison between LED and Laser Diode

As we can see from figure 1-3 all of the light that goes over the critical current is laser light

and so the external cavity semi-conductor laser that we built needs Anti-Reflective Coating

because the method we want to use needs an external cavity laser that has been covered with AR

Coating and a Diffraction Grating We use this configuration first by shooting the laser to the

grating and this will be shot back to the laser creating the external resonance cavity which is

shown in figure 1-4

Fig 1-4 External Cavity Design

13

Two configurations are shown the Littrow Configuration and the Littman-Metcalf

Configuration The Littrow configuration contains a collimating lens and a diffraction grating as

the end mirror The first order diffracted beam provides optical feedback to the laser diode which

has AR Coating The emission wavelength can be turned by rotating the diffraction grating A

disadvantage is that it also changes the direction of the output beam

In the Littman-Metcalf configuration the grating orientation is fixed and an additional mirror

is used to reflect the first order beam back to the laser diode The wavelength can be turned by

rotating that mirror This configuration offers a fixed direction of the output beam and also tends

to exhibit smaller line width as the wavelength selectivity is stronger A disadvantage is that

zero order reflection of the beam reflected by the tuning mirror is lost so that the output power is

less than that of a Littrow laser

13 Methodology

The aim of this research is to find the mechanical properties of materials after being

subjected to tensile testing through finite element analysis observations and determine what

material is best for our purposes taking into consideration the strength and durability of the

material among other properties to find use and applications for the AR coated laser diodes to

further improve the grasp of the Bose-Einstein condensation working principles

14 Organization of the Thesis

The research paper includes five chapters

1 Chapter 1 explains the motivation background objective and methodology of this study

2 Chapter 2 explains the working principles and basic knowledge needed to understand this

study

3 Chapter 3 explains the tensile testing in detail steps methods and results

4 Chapter 4 explains the AR coating in detail steps methods and results

5 Chapter 5 is the conclusions taken from the results shown in chapter 3 and 4 and

recommendations done after arranging and critical thinking

14

Chapter 2 BASICS THEORIES

21 Tensile Testing

After a specimen is tested with the use of tensile testing we can get the Stress-Strain Curve using the

relation between tension and displacement Typical curves are shown in Fig 2-1

(a) Ductile materials (b) Brittle materials

Fig 2-1 Stress-Strain Curve

The curve is unique for each material and is found by recording the amount of deformation at distinct

intervals of tensile or compressive loads Thanks to the use of the Stress-Strain curve we can get very

useful information such as

211 Youngrsquos Modulus (E)

As shown in Fig 2-1 as long as the external load is not greater than the Proportional Limit the Stress

(σ) and Strain (ε) remain as a linear relation fulfilling Hookersquos Law

σ = Eε

The slope is the constant factor the inverse of the modulus of elasticity E also called Youngrsquos

modulus When the external load goes over the proportional limit the stress-strain relationship doesnrsquot

follow the linear relation anymore but the deformation remains flexible When the load is released the

deformation is completely eliminated and the specimen goes back to its original state This is called

15

Elastic Deformation When the external load goes over the Elastic limit only then does the specimen

presents Plastic Deformation This type of deformation which is irreversible even when the load is

removed comes after the material does under elastic deformation so this means the object will first come

part way to its original shape Common metals and ceramics have roughly the same elastic limits

212 Yield Strength and Yield Point

Some materials display very evident yield phenomena while some materials donrsquot as shown in Fig

2-2 After we exceed the elastic limit if we continue to exert load when we arrive to a certain value

which differs under different materials and external conditions there is sudden decrease in stress and this

is called the Yield Strength and can be defined as the stress at which a material begins to deform

plastically using the equation

σyield =

Where P is the tension force and Ao is the original cut-off area

The stress remain at a certain value after the decrease but the strain increases this phenomena can be

easily appreciated when studying the behavior of common Carbon Steel Fig2-2 (a) but most metals (like

Aluminum Copper or High Steel Carbon) donrsquot display this kind of behavior as shown in Fig 2-2 (b)

Arriving to this point is very difficult and the most commonly used method for this is to add a 02 or

0002 offset yield strength to the curve This point is held constant on the strain axis of the curve and

from the 0002 position we draw a straight line parallel to the linear relationship line the point at where

this line and the stress-strain curve intercept is the point we take as the 02 offset yield strength

(a)Evident (b) Non-evident

Fig2-2 Stress-Strain Curve Comparison on Metals

16

213 Ultimate Tensile Strength and Breaking Strength

After materials undergo yield they keep lending strength and hardening phenomena occurs (work

hardening) on the material and the external load increases When it has reached the highest point this is

called the Ultimate Tensile Strength (UTS) as shown in Fig2-1 The UTS is defined as

σUTS =

Where Pmax is the load at the materialrsquos ultimate tensile strength point and Ao is the original cut-off

area For brittle materials the ultimate tensile strength is the most important mechanical property for

ductile materials the ultimate tensile strength is not commonly used for industrial and designing purposes

because upon arriving to this value the material already has forgone great plastic deformation After the

specimen goes through UTS there will be necking phenomena which is a mode of tensile deformation

where relatively large amounts of strain localize disproportionately in a small region of the material It

results from instability during tensile deformation when a materialrsquos cross-sectional area decreases by a

greater proportion than the material strain hardens The specimen continues to elongate until it finally

breaks and the load at this point is called Breaking Strength The breaking strength is defined as the

greatest stress in tension that a material is capable of withstanding without rupture

Where Pf is the load at the materialrsquos breaking strength point and Ao is the original cut-off area

214 Poissonrsquos Ratio (ν)

For elastic deformation when materials are compressed in one direction they tend to expand in the

other two directions perpendicular to the direction of compression This is called the Poissonrsquos Effect

The Poison Ratio is a measure of the Poissonrsquos effect It is the ratio of the fraction of expansion divided

by the fraction of compression for small values of these changes

ν=-

215 Strain Gauge Basic Principles

The strain gauge is a device used to measure the strain of an object Itrsquos an elongated metal resistor

which is attached to the specimen being measured and when the specimen is under strain and starts to

deform the strain gauge will have a change in the resistance With the change in value we can calculate

the elementrsquos strain or elastic modulus and the Poissonrsquos ratio

It takes advantage of the physical property of electrical conductance and its dependence on the

conductorrsquos geometry When the electrical conductor (the specimen being tested) is stretched within the

limits of elasticity such that it does not break or deform plastically it will become narrower and longer

17

which increases the electrical resistance through-out From the measured resistance of the strain gauge

the amount of stress may be inferred by using the relations

R=

Where R is the original resistance value is the electrical resistivity lo is the original length of the

conductor and Ao is the original cross sectional area of the conductor If after the application of tension

the change in length is Δl let the length of the specimen be l = l + Δlo and the tension is the same

through-out So

And the resistance is

The Gauge Factor is the ratio of relative change in electrical resistance to the mechanical strain in

other words it is the relative change in length It is defined as

The strain gauge was invented in 1938 by Edward E Simmons and Arthur C Ruge and the most

common type consists of an insulating flexible backing which supports a metallic foil usually made of a

brass-nickel alloy It is attached to the specimen by a suitable adhesive As the object is deformed the foil

also deforms and this causes the electrical resistance to change Then this is usually measured using a

Wheatstone bridge shown below and is related to the strain by the Gauge Factor

Fig2-3 Basic Structure of Strain Gauge

18

Fig 2-4 Strain gauge attached to Wheatstone bridge

22 Hardness Testing Basic Principles

221 Brinell Scale BHN

The Brinell Scale characterizes the indentation hardness of materials through the scale of penetration

of an indenter loaded on a material specimen The typical test uses a 10mm diameter steel ball as indenter

(usually of value equal to BHN450) with a 29kN force For softer materials smaller force is used The

indentation is measured and BHN is calculated using the relation

BHN =

radic

Where F is the applied force usually within the range of 100 250 500 750 1000 1500 2000 2500

and 3000 kgf D is the diameter of indenter usually within the range of 5mm or 10mm plusmn0005 margin

and d is the diameter of indentation usually around 2mm Its units are of Kgmmsup2 but are not normally

written

First proposed by Swedish engineer Johan August Brinell in 1900 it was the first widely used and

standardized hardness test in engineering and metallurgy although the large size of indentation and

possible damage to specimen limits its usefulness

Fig 2-5 Brinell Indentation Fig2-6 Brinell Hardness Tester

19

222 Rockwell Scale HR

The Rockwell scale is a hardness scale based on the indentation hardness of a material The Rockwell

test determines the hardness by measuring the depth of penetration of an indenter under a large load

compared to the penetration made by a preload The indenter is forced into the specimen under a

preliminary load When equilibrium is reached a measuring device follows the movements of the

indenter and responds to changes in depth of penetration of the indenter While the preload is still being

applied additional major load is applied resulting in increased penetration When equilibrium is reached

again the major load is removed but the preload is maintained Removing the major load allows partial

recovery and reduces the depth of penetration The permanent increase in depth of penetration resulting

from the application and removal of the major load is used to calculate the Rockwell number using the

relation

HR = E ndash e

Where E is a constant depending on the form of the indenter 100 units for diamond indenter and 130

units for steel ball indenter e is the permanent increase in depth of penetration due to the major load

measured in units of 0002mm

Fig 2-7 Rockwell Indentation

When testing materials indentation hardness is related linearly to the tensile strength The important

relation permits economically important nondestructive testing of bulk metal deliveries with lightweight

equipment like the Rockwell tester shown below in figure 2-7

Fig 2-8 Rockwell Hardness Tester

20

There are different scales denoted by a single letter that use different loads or different indenters

The result is a dimensionless number denoted as HR X where X will be the letter denoting the scale as

shown below in table 2-1

Table 2-1 Rockwell Hardness Test Scale

Differential depth hardness measurement was first conceived in 1908 by Viennese professor Paul

Ludwik It eliminated the errors associated with the mechanical imperfections of the system such as

backlash and surface imperfections in the specimen Rockwell testing has an advantage over Brinell

testing because the latter was slow itrsquos not useful on fully hardened steel and left too large an impression

to be considered nondestructive

The tester was co-invented by Hugh M Rockwell and Stanley P Rockwell The requirement for this

tester was to quickly determine the effects of heat treatment on steel bearing races

21

223 Vickers Hardness Test HV

This is a type of microindentation hardness test where a diamond indenter of specific geometry is

impressed into the surface of the test specimen using a known applied force ranging from 10 to 1000

grams This type of tests usually has forces of 2N and produce indentations of about 50μm They can be

used to observe changes in hardness on the microscopic scale It is difficult to standardize the

microhardness measurements because it has been found that the microhardness of almost any material is

higher than its macrohardness The values also vary with load and work-hardening effects of materials

The Vickers test is often easier to use than other hardness tests because the required calculations are

independent of the size of the indenter and the indenter can be used for all materials It can be used for all

metals and has one of the widest scales among hardness tests The unit of the Vickers test is denoted as

HV and can be converted to units of Pascal (Pa) but it is not a measurement of pressure The hardness

number is determined by the load over the surface area of the indentation and not the area normal to the

force

A square-based pyramid shaped diamond is use as the indenter It has been established that the ideal

size of a Brinell impression was 38 of the ball diameter As two tangents to the circle at the ends of a

chord 3d8 long intersect at 136plusmn05deg it was decided to use this as the angle of the indenter giving an

angle to the horizontal plane of 22deg on each side The HV number is determined by the ratio FA where F

is the force applied to the diamond in kgf and A is the surface area of the resulting indentation in mmsup2 A

can be determined by the relation

A =

Where A is the surface area of indentation and d is the average length diagonal left by the indenter

This can be approximated as

A =

Then the Vickers Number is

HV =

=

Vickers hardness number is reported as xxxHVyy or xxxHVyyzz (if duration of applied force differs

from 10s to 15s) where xxx are replaced by the hardness number yy is the load in kg and zz indicates

loading time The values are generally independent of test force

The test was developed in 1921 by Robert L Smith and George E Sandland at Vickers Ltd as an

alternative to Brinell method to measure the hardness of materials

22

Fig 2-9 Vickers Indentation Fig 2-10 Vickers Hardness Tester

23 AR Coating

231 Bose-Einstein Condensate

The Bose-Einstein Condensate or BEC is a state of matter of a dilute gas of bosons cooled to

temperatures very near absolute zero around 0K or -27315degC Under such conditions a large fraction of

the bosons occupy the lowest quantum state where the quantum effects become apparent on a

macroscopic scale This gave birth to the Bose-Einstein Statistics which are the rules that govern the

behavior at this state It is one of the two possible ways in which a collection of indistinguishable particles

may occupy a set of available discrete energy states The aggregation of particles in the same state

accounts for the cohesive streaming of laser light and the frictionless creeping of superfluid helium (an

application discussed later) Bose and Einstein recognized that a collection of identical and

indistinguishable particles can be distributed this way This theory applies only to those particles not

limited to single occupancy of the same state particles that do not obey the Pauli Exclusion Principle

restrictions Such particles are the Bosons named after the statistics that correctly describe their behavior

This phenomenon was first predicted by Satyendra Nath Bose around 1924 when he considered how

groups of photons behave He then asked Albert Einstein for help publishing his discoveries to which

Einstein agreed and gave follow up supporting these findings The resulting efforts became the concept of

a Bose gas governed by the Bose-Einstein Statistics described above Einstein demonstrated that cooling

bosonic atoms to a very low temperature would cause them to condense into the lowest accessible

quantum state resulting in a new form of matter

The first gaseous condensate we produced by Eric Cornell and Carl Wieman at the University of

Colorado at Boulder NIST ndash JILA lab sung a gas of rubidium atoms cooled to 170 nK which earned

them the 2001 Nobel Prize in physics together with Wolfgang Ketterle from MIT The transition to BEC

occurs below a critical temperature which for a uniform three dimensional gas consisting of

non-interacting particles with no apparent internal degrees of freedom is given by

23

Tc =

(

)

asymp 33125

Where Tc is the critical temperature n is the particle density m is the mass per boson h is the

reduced Planck constant k is the Boltzmann constant and ζ is the Riemann zeta function

There are two classes of elementary particles defined by whether their quantum spin is a nonnegative

integer or an odd half integer A Bose-Einstein Condensate is shown below in figure 2-11

Fig 2-11 Bose Einstein Condensate at different scales

Bosons are the particles whose quantum spin is a nonnegative integer (s = 0 1 2 etc) Examples of

bosons include fundamental particles (Higgs Boson Photons W and Z Bosons Gluons Gravitons etc)

composite particles (Mesons Hadrons Nuclei and Atoms of Carbon-12 and Helium-4) and

quasi-particles Bosons are considered force carrier particles The Bosons differ from Fermions in that

there is no limit to the number that can occupy the same quantum state This is called the Pauli Exclusion

Principle

The Pauli Exclusion Principle says that no two identical fermions may occupy the same quantum state

simultaneously in other words this means that the total wave function for two identical fermions is

anti-symmetric with respect to exchange of the particles This means that no two electrons in a single

atom can have the same four quantum numbers

Fermion is any particle characterized by Fermi-Dirac Statistics and follows the Pauli Exclusion

Principle described above Quarks Leptons and composite particles (Hadrons Nuclei and Atoms of

Carbon-13 and Helium-3) made of an odd number of these are considered Fermions It can be an

elementary particle such as the electron or a composite particle such as the protons Following the Pauli

24

Exclusion Principle only one fermion can occupy a particular quantum state at any given time If multiple

fermions have the same spatial probability distribution then at least one property of each fermion must be

different Fermions are usually associated with matter because composite fermions are key building

blocks of matter (neutrons and protons)

Fermionsrsquo behavior by the Fermi-Dirac Statistics which describes the energies of single particles in a

system comprising of many identical particles It applies to identical particles with half-odd integer spin

in a system of thermal equilibrium The particles in the system are assumed to have negligible mutual

interaction This allows the many-particle system to be described in terms of single-particle energy states

The result is the Fermi-Dirac distribution of particles over these states and includes the condition that no

two particles can occupy the same state which has considerable effect on the properties of the system

In quantum mechanics the position of an object is uncertain An object has a definite probability of

being at any given point in space This probability is encoded in the wave function mentioned earlier If

one concentrates a large number of identical bosons in a small region then it is possible for their wave

functions to overlap so much that the bosons lose their identity When this happens thatrsquos a Bose-Einstein

Condensate It is only possible at very low temperatures because at high temperatures the individual

bosons have small wave functions and move rapidly which causes them to fly apart

For now applications are still restricted because there are still some setbacks regarding BECs They

are extremely fragile they are being produced in small quantities with just a few million atoms at a time

and finally they can only be made from certain types of atoms Some examples are the atom laser Ketterle

in which a conventional light lase emits a beam of coherent photons this means they are all in phase and

can be concentrated to an extremely small bright spot BECs can slow down light as demonstrated by

Prof Lene Hau PhD in 2001 by the use of a superfluid [7] These manipulations could develop into

new types of telecommunications technology optical storage and quantum computing

BECs are related to super-fluidity and super-conductivity Super-fluidity is the state of matter in

which the behavior is that of a fluid with zero viscosity It was discovered in liquid helium but now it has

applications in astrophysics high-energy physics and theories of quantum gravity

Super-conductivity is a phenomenon of exactly zero electrical resistance and expulsion of magnetic

fields occurring in certain materials when cooled below a characteristic critical temperature A

super-conductor is shown below in figure 2-12

Fig2-12 Super Conductor

25

232 AR Coating Basic Principles

Anti-reflective (AR) coating is a type of optical coating applied to the surface of lenses and other

optical devices (in our case we planned to apply it to a laser diode) to reduce reflection This improves

the efficiency of the system since less light is lost The primary benefit is the elimination of the reflection

itself

When light the medium (glass) it will produce reflection if 100 of the light comes from the air and

enters the glass because therersquos a difference between the index of refraction some of the light will go out

and when the light is coming out of the glass into the air once again because of the difference between

index of refraction some of the light wonrsquot be able to pass through the medium

When the light makes the first trip into the glass there was a loss of about 4 in the reflection and

when the light makes the trip back outside there was another loss of about 4 so when we assume that

100 of the light interacts with the medium actually therersquos just about 92 acting (we neglect the light

absorbed by the glass around 05) To illustrate this idea please refer to figure 2-13

Fig 2-13 Simple Model for Light in Glass Medium

When we apply the AR Coating the light that enters will only have a loss of about 05 and when

making the trip back outside again only 05 of light is loss so we get the result of increasing the light

passing through up to 99 (again neglecting the light absorbed by the glass around 05) To illustrate

this idea please refer to figure 2-14

26

Fig 2-14 Simple Model for Light in Glass Medium after AR Coating

The AR Coating can reduce reflection of incoming light In the case that light hits perpendicular to

the surface of the medium the intensity of the reflection can be calculated using the Reflection

Coefficient

Where n0 and ns are the refractive indices of the first and second media respectively The value of R

varies from 0 (no reflection) to 1 (all light reflected) and is usually quoted as a percentage

Complementary to R is the transmission coefficient or Transmittance If absorption and scattering are

neglected then the value of Transmittance is always 1-R then if a beam of light with intensity I is

incident on the surface a beam of intensity RI is reflected and a beam with intensity TI is transmitted to

the medium

The optimal value is called the Optimal Index of Refraction and is described as

For glass with ns around 15 in air (n0 around 10) then the optimum refractive index will be n1 =

1225

To reduce the refraction in this case we now mean the one that is produced inside the chamber of the

Laser diode the easiest way is to apply a low reflectivity AR coating on the surface of the laser To

measure the appropriate thickness of the coating layer we can use the equations described above By

applying a coat exactly

thickness film we can assure that a certain wavelength is transmitted The

27

reflected waves from the back of the glass medium will be half a wavelength out of phase So they

interfere destructively Because all reflected waves are interfered the maximum amount of light passes

through the coating Please refer to figure 2-15 to illustrate this idea

Fig 2-15 Light Passing through AR Coat and Glass

The most common process to attain this final product is by vacuum deposition For the best coating

results we need to lower the pressure inside the vacuum system to torr

Fig 2-16 Lens without (Top) and With (Bottom) AR Coating

28

233 Laser Diode Basic Principles

A laser diode is a laser whose active medium is a semiconductor similar to that found in

light-emitting diodes (LEDs) Please refer to figure 2-17 The most common type of laser diode is formed

from a p-n junction and powered by injected electric current

Fig 2-17 Laser Diode

Laser diodes are formed by doping a very thin layer on the surface of a crystal wafer The crystal is

doped to produce the n-type region and a p-type region one above the other

By referring to figure 1-2 we can see the basic structure of a working laser When the laser diode has

a current passing through it the light will get excited inside its gain medium and then will start to

resonate this process is called pumping The current exceeds the critical current and then it comes out as

laser light Please refer to figure 1-3 Since we use an external cavity laser we need to apply the AR

coating to the diode and adjust a diffraction grating The laser light comes out the diode and bounces on

the grating making the resonance externally and this becomes the ldquocavityrdquo as shown in figure 2-18

Fig 2-18 Tunable Laser Basic Configuration

29

The most important feature of the external cavity laser is that we can adjust the wavelength easily just

by changing the diffraction gratingrsquos angle and in the end this is the output wavelength of the laser For

different wavelengths there will be different levels of visible light as shown in figure 2-19

Fig 2-19 Light Spectrum

234 Quartz Microbalance System

A Quartz Crystal Microbalance is an instrument that measures a mass per unit area by measuring the

change in frequency of a quartz crystal resonator The resonance is disturbed by the addition or removal

of a small mass due to oxide growthdecay or film deposition (which is the case in our study) at the

surface of the acoustic resonator The QCM can be used under vacuum in gas phase and more recently in

liquid environments It is useful for monitoring the rate of deposition in thin film deposition systems

under vacuum Frequency measurements are easily made with high precision

For our research we used the Sigma Instruments SQM-160 RateThickness Monitor shown in figure

2-20

Fig 2-20 Front and Back Panels of SQM-160

30

The microbalance uses Quartz as the resonator Quartz is one member of the family of crystals that

experience the Piezoelectric Effect

Piezoelectricity is the charge that accumulates in certain solid materials in response to applied

mechanical stress It means electricity resulting from pressure It was discovered in 1880 by Jacques and

Pierre Curie It is understood as the linear electromechanical interaction between the mechanical and the

electrical state in crystalline materials with no inversion symmetry It is a reversible process in that

materials exhibiting direct piezoelectricity also exhibit the reverse This means that the internal generation

of electrical resulting from applied mechanical force and vice versa

By using the piezoelectric effect we can probe as an acoustic resonance by electrical means Applying

alternating current to the quartz crystal induces oscillations This creates a shear wave We can use these

qualities to determine the resonance frequency at high accuracy

The frequency of oscillation of the crystal is partially dependent in the thickness of the crystal During

normal operation all the variables are held constant so a change in thickness correlates directly to a

change in frequency As mass is deposited or etched away the thickness increases or decreases and so the

frequency of oscillation changes accordingly With some simplifying assumptions the frequency change

can be quantified and correlated precisely to the mass change using the Sauerbreyrsquos Equation

Developed by G Sauerbrey in 1959 it is a method for correlating changes in the oscillation

frequency of a piezoelectric crystal with the mass deposited on it It is defined as below

Where f0 is the Resonant frequency Δf is the Frequency change Δm is the mass change A is the

piezoelectrically active area of the crystal q is the Density of quartz (2648 gcmsup3) and μq is the Shear

modulus of quarts(2947x gcmssup2)

Because the film is treated as an extension of thickness Sauerbreyrsquos equation only applies to systems

in which the following 3 conditions are met

Deposited mass must be rigid

Deposited mass must be distributed evenly

The frequency change

lt002

If the change is greater than 2 the Z-match method must be used to determine the change in mass

It is defined as

Where fL is the frequency of the loaded crystal fU is the resonant frequency Nq is the frequency

constant (1668x HzAring) Δm is the mass change A is the piezoelectrically active area of the crystal

31

q is the density of quartz Z is the method constant f is the density of film μq Is the shear modulus of

quarts and μf is the shear modulus of film

The Sauerbrey equation cannot be applied to systems under liquid medium

The crystals are seed crystals plated with gold on both top and bottom for applications A crystal is

shown in figure 2-21 The QCM consists of a thin piezoelectric plate with electrodes evaporated on both

sides Due to the piezoelectric effect AC voltage across the electrodes induces a shear deformation and

vice versa The electromechanical coupling provides a simple way to detect an acoustic resonance by

electrical means

The Z also called Z-factor is a constant value for different materials and it is shown together with the

density of different materials in table 2-2 below

Fig 2-21 QCM Crystals

The Oscillator of the SQM-160 is shown in figure 2-22 and the equivalent circuit for the Resonant

Oscillator is shown in figure 2-23

Fig 2-22 SQM-160 Oscillator

32

Fig 2-23 Oscillator Circuit

33

Table 2-2 Z-Ratios for Different Materials

Table 2-2 Continued

34

Table 2-2 Continued

35

Table 2-2 Continued

36

Table 2-2 Continued

37

Table 2-2 Continued

38

Table 2-2 Continued

235 Vacuum Chamber System

Vacuum Evaporation is the process of depositing thin films of materials onto surfaces The technique

consists of pumping a vacuum chamber to pressures of less than torr and heating a material to

produce a flux of vapor in order to deposit the material onto a surface The material to be vaporized is

typically heated until its vapor pressure is high enough to produce a flux several Angstrom per second by

using an electrically resistive heater or bombardment by a high voltage beam The process was invented

by Henri Nestle in 1886 for food industry

In here the system has been pumped to a vacuum of Torr When a high current is passed

through the filament boat the filament boat is heated over the desired metal evaporation temperature and

so evaporation starts When the evaporation process is finished and the metal cools down crystals

condensate in the surface of the wafer From the weight of the evaporated material the distance between

the filament boat and the wafer we are able to calculate the deposition thickness and we can also use the

mass detector follower like the Quartz crystal resonator microbalance system In the process of

evaporation we usually use a board in between the filament boat and the wafer This is because before we

arrive to the desired evaporation temperature there will be some impurities that will be vaporized in the

controlled environment so we first use a small current and the board in between to get rid of those

impurities and this raises the purity of the deposition material

39

A vacuum evaporation system is shown in figure 2-24

Fig 2-24 Vacuum Evaporation System

Rough Vacuum 760 ~ 1 torr

Medium Vacuum 1 ~ torr

High Vacuum ~ torr

Ultra-High Vacuum Lower than torr

Table 2-3 Classification of Vacuum

For our study we need to use a Turbo Pump A regular turbo pump is shown in figure 2-25

Fig 2-25 Turbo Pump

For our research we used the Pfeiffer TCP 015 Electronic Drive Unit and Granville Phillips 375

Convectron shown below in figure 2-26

40

Fig 2-26 Control and Measurement Equipment

The electronic drive controls the turbo pump and the Convectron measures the pressure inside our

chamber The turbo pump is a type of vacuum pump used to maintain high vacuum Most turbo pumps

are centrifugal When we start the pumping we need to use a mechanical pump so as to decrease the

pressure inside the system from constant atmospheric pressure to torr and then the use dispersion

pump to continue the vacuum until we get to the desired pressure We need to notice though when we

start the dispersion pump we canrsquot turn off the mechanical pump and they both need to run together If

we need to turn off the pumping we first turn off the dispersion pump wait for it to completely stop and

then turn off the mechanical pump

Our completely assembled system is shown in figure 2-27 below

Fig 2-27 Complete System

41

Chapter 3 TENSILE TESTING IN DEPTH

31 Experimentrsquos Purpose and Principles

By means of Universal testing machine and Strain gauges we were able to observe discuss and

analyze the phenomena created when a specimen of certain material is manipulated under an external load

and determine the stress strain and deformation values later we can use the graphing methods of

stress-strain diagram to describe it

The main point of this experiment is that after the tensile specimen is tested use computer analysis

and the actual strain data and after statistical adjustment make the final results report (Tensile testing

experiment is in accordance with ASTM E8)

32 Experimentrsquos Equipment

321 Universal Testing Machine

For the materials testing experiment part of this research we use a Universal Testing Machine as

shown in figure 31 The maximum load it can apply is 100 Ton After the test specimen is secured on the

device with the use of instrumentation the load exerted and the effects of this become apparent on the

specimen and even the smallest of changes can be recorded For our research we used the Chun Yen

Testing Machines Co Ltd 100 Ton Micro Computer Universal Tensile Tester

Fig 31 Universal Testing Machine

42

Table 31 shows the specifications for this machine

Max Capacity 100 Ton

Accuracy plusmn1

Tension (mm) Max Space 1150mm

Grip for Rod 20-70mm

Ram Stroke 250mm

Effective Column Interval 940mm

Crosshead Speed 300mmmin

Testing Speed 0-50mmmin

Volume of Machine 1700times1000times3350mm(LtimesWtimesH)

Volume of Control Panel 1000times800times1500mm(LtimesWtimesH)

Weight 8000kg

Power 3∮220V 20A

Computer AMD K6-2-350

OS Windows XP

Screen 15rdquo CRT

Table 3-1 Chun Yen Testing Machine Specs Table

The connections diagram is shown in figure 3-2

Fig 3-2 Diagram for System Connections

43

When the test specimen is placed when the external force is applied the Load Cell can measure the

size of the applied force and the Encoder measures the expansion rate of change The Local Controller

receives all the information from the 2 units after arranging the results they are displayed in the

computer and they can be afterwards submitted for more complex analysis such as Finite Element

Analysis and we can get the Stress-Strain Diagram

322 Strain Measurement Equipment

The equipment used in our research provides a four-channel measurement that means we can use up

to 4 strain gauges at a time to do our measurements and provides 3 different bridge arrangements as

shown in figure 3-3

(a) (b) (c)

Fig 3-3 Input Connections for Strain Indicator

Figure 3-3 (a) is the Quarter Bridge (b) is the Half Bridge and (c) is the Full Bridge and Transducers

For our study we used the Quarter Bridge and use the Strain Gauge values to decide the position of the

connecting wires The Strain indicator is shown in figure 3-4

Fig 3-4 Vishay Micro-Measurements Model P3 Strain Indicator and Recorder

44

Input Connections Tool Free eccentric lever release

4-channel input

Wire diameter16-28AWG

Bridge Configurations Quarter- Half- and Full Bridge

Bridge Impedance 60-2000Ω

Display 128 64 pixel FSTN positive gray LCD

Data Conversion AD Converter filter

Measurement Range Resolution Strain Range plusmn155mVV

Resolution plusmn00005mVV

Measurement Accuracy plusmn01 of reading plusmn3 counts

Gage Factor Control 0500-9900

Balance Control Software either manual or automatic

Bridge Excitation 15VDC nominal

Communication Interface USB Cable Included

Data Storage Removable Media Card

Shunt Calibration Across bridge completion resistors controlled

by software When Gage Factor=200

120Ω350Ω1000Ω

Analog Output Value 0 to 25V max

Ranges plusmn320 microε plusmn3200 microε plusmn32000 microε

Error 05 output voltage +5mV

Max Error 14 output voltage + 20mV

Update rate 480 samplessec

Output Load 2000Ω

Power Battery Two Alkaline D cells

Battery life 400 hours typ

USB 5V 100mA

Operational Environment Temperature 0-50

Humidity Up to 90 Non-condensing

Case Aluminum Alloy

Size and Weight 228times152times152(mm) 20(kg)

Table 3-2 Vishay Micro-Measurements Model P3 Strain Indicator and Recorder Specs

45

323 Strain Gauge

The strain gaugersquos main basic principle is to use a resistancersquos characteristics to measure the strain

The inside connections of the strain indicator are shown in figure 3-5

Fig 3-5 Inner Connections

As shown above this is a quarter-bridge connection We connect equal-length 3 wires to the 2

connections allowed by the strain gauge wire 1 and 3 can be used to cancel out the effects of temperature

to the resistance and because of the addition of wires 1 and 3 wire 2 can directly measure the experiment

results from the strain gauge and therefore the strain developed with no influence of temperature

If there were no two measuring leads then the relations will be

R 4 =R g +2R L

Where Rg is the Strain Gauge Value and RL is the wire resistance then

4

4

R

R=

Lg

g

RR

R

2

=

gL

gg

RR

RR

21

amp

4

4

R

R=

g

g

R

R(1- L)

Where L is the Signal Loss Factor and so

L =gL

gL

RR

RR

21

2

g

L

R

2R if

g

L

R

2Rltlt1

46

(Actual Value R g =120R L =08g

L

R

2Ris always much smaller than 1)

R 4 =R g +2R LR 2 =R 3 =rR gR 1 =R g 32 RR =0

V 0 =V 2)1( r

r

(

4

4

R

R-

1

1

R

R)

The first term describes loss attenuation effects second term describes loss of balancing capabilities

effects

V 0 =V 2)1( r

r

[

)2

(Lg

g

RR

R

+

T

Lg

g

RR

R

)

2( + T

Lg

L

RR

R

)

2

2( -(

g

g

R

R) T ]

The first term describes loss attenuation effects and loss of balancing capabilities effects the second

third and fourth terms describe the temperature effects on the wire

For the three-wire method we have

L =gL

gL

RR

RR

1

g

L

R

R if

g

L

R

Rltlt1

V 0 =V 2)1( r

r

[

)(Lg

g

RR

R

+

T

Lg

g

RR

R

)( + T

Lg

L

RR

R

)

2( -

T

Lg

g

RR

R

)( - T

Lg

L

RR

R

)

2( ]

V 0 = V2)1( r

r

)(

Lg

g

RR

R

In the last four terms inside parenthesis we can see the effects of temperature being cancelled out and the

effect on first term is not great so this is the reason why in our research we use three wires

47

324 Specimen Measurements

The tensile specimens used in this research are compliant of ASTM E8 Tensile parameters as shown

in figure 3-6

Fig 3-6 Tensile Specimen

Diameter

D(mm)

Gauge

Length

G(mm)

Smallest

Arc

Radius

R(mm)

Shortest

Area

A(mm)

Total

Length

L(mm)

Clamping

Area

Length

B(mm)

Clamping

Area

Diameter

C(mm)

Bar 125 02 625 01 gt10 gt75 ~ 145 ~ 35 20

Table 3-3 Specifications for Round Bar

33 Experiment Procedure

1 Attaching the Strain Gauge to the Tensile Specimen

(1) Prepare 1 ASTM E8 compliant tensile specimen round bar as shown in figure 3-7

(2) Prepare Strain Gauge as those described in table 3-4

(3) Prepare other consumables and adhesive agent such as epoxy adhesive or

cyanoacrylate adhesive as shown in figure 3-8

48

Fig 3-7 Actual Tensile Specimen

Fig 3-8 Other Materials Used (Such as Alcohol gauze transparent tape adhesive)

Gage Type

EA-06-120LZ-120E

Resistance in ohms at 24∘C

1200plusmn03

Gage Factor at 24∘C

2075plusmn05

Transverse Sensitivity at 24∘C

(+07plusmn02)

Table 3-4 Specifications for Strain Gauge

2 Attaching Strain Gauge

As shown in following figures we shall explain the attachment of the strain gauge

(1) Use sand paper and a rasp to clean thoroughly the surface where the strain gauge will be

attached to

49

(a)

(2) Use alcohol to wash the surface where the strain gauge will be attached and use gauze to rub

it off

(b)

(3) Find a clean surface and clean it with alcohol and gauze

(c)

(4) Place the strain gauge in the clean surface Use a piece of transparent tape on top of the strain

gauge after securely placed rip it off the surface carefully

50

(d)

(5) Use a piece of white paper to mark the place where the strain gauge will be attached and in

this way we can make sure that the strain gauge will be placed as horizontally and vertically

correct as possible

(e)

(6) In the place where we had our mark place the strain gauge

(f)

(7) Carefully lift one side of the tape and apply some of the adhesive agent to both the strain

gauge and specimenrsquos surface

(g)

51

(8) We need to make sure that the gauge and the specimen will be firmly attached so we gently

apply pressure with our thumb

(h)

(9) After the adhesive is fully dry we can carefully rip off the tape

(i)

(10) We need to do the whole process twice one for the horizontally placed strain gauge and one

for the vertically placed strain gauge

52

(j)

(11) We now proceed to solder the wires to the strain gauge

(k)

(12) After soldering we use a Volt Multimeter to measure that there is no contact between wires

If there is none then the specimen is ready for testing

(l)

(13) We now need to measure a 5cm distance and mark it to check and compare the elongation

before and after the tensile testing

(m)

53

Fig 3-9 Specimen-Strain Gauge Process

3 Tensile Test

(1) Enter the computer application that controls the tensile testing machine

(2) Turn on the tensile testing machine main switch

(3) Adjust the hydraulic pump to go back to its original position

(4) Bring the lowering motor down to a distance enough so as to attach the tensile specimen to the

system open the clamps and secure the specimen

(a)

(5) Connect all the necessary wires to the strain indicator equipment

54

(b)

(6) Start the ascending motor and wait for the expansion

(c)

Fig 3-10 Specimen-Tensile Testing Process

4 Start the Test

(1) Enter the software application and enter some variables needed for the experiment in the

specific screen

(2) Go back to the main screen and press the [測試] (measure) button to start the test and auto

recording in the software

(3) After the specimen breaks the mechanical device will automatically stop and ask the user to

enter the total displacement We take out the specimen from the testing machine and adjust the

machinersquos position back to its original position

(4) Save the results information

(5) Record the results from the strain indicator

34 Results

From this experiment we can get the Poissonrsquos Ratio Youngrsquos Modulus and Yield Strength etc and

because of the slippage phenomenon in the clamp at the moment of the test then the Elastic Limit will

display some yield phenomena So omit any undesirable results we just take the Yield portion of the

results as reference

In the process of the experiment the most important part to attend to is the attaching of the strain

gauge because the gaugersquos purpose is to measure the strain developed during the test and this strain

might be very small If the gaugersquos angle change during the test ie is not well attached this will affect

the accuracy of the measurements of Poissonrsquos ratio and Youngrsquos modulus

55

The materials provided by the manufacturer are SUM 23 and SUM 43 steel round bars and these two

types of materials have been through different heat treatment processes so they can be sub-divided

further into untreated material heat-treated material and black surface heat treated material for the two

materials with heat treatment the treatment process and finished are different In the end we only have

the mechanical properties that were calculated after our research of these materials

All of the specifications are identical to those shown in figure 3-6

341 SUM 23

Fig 3-11 SUM 23 Untreated Material

Number 7 10

Hardness(HRB) 74 75

Yield Stress (MPa) 448 440

Tensile Strength (MPa) 544 560

Poissonrsquos Ratio 029 027

Youngrsquos Modulus (GPa) 203 210

Cut-off Area Shrinking () 42 41

Elongation () 1125 1011

Table 3-5 Mechanical Properties of SUM 23 Untreated

56

Stress-Strain Diagram

(a)

(b)

57

Fig 3-12 Stress-Strain Diagrams for (a) 7 Round Bar and (b) 10 Round Bar

Cut-Off Area

(a)

(b)

Fig 3-13 Cut-Off Area of (a) 7 Round Bar and (b) 10 Round Bar

58

SUM 23 Nickel Round Bar

Fig 3-14 SUM 23 Nickel Material

Number 1 2 3 4

Hardness(HRB) 48 50 49 48

Yield Stress (MPa) 370 370 380 400

Tensile Strength (MPa) 455 451 450 450

Poissonrsquos Ratio 028 046 029 026

Youngrsquos Modulus (GPa) 243 303 246 206

Cut-off Area Shrinking () 803 803 726 601

Elongation () 566 65 602 647

Table 3-6 Mechanical Properties of SUM 23 Nickel

59

Stress-Strain Diagram

(a)

60

(b)

(c)

(d)

61

Fig 3-15 Stress-Strain Diagrams for (a) 1 Round Bar (b) 2 Round Bar (c) 3 Round Bar and (d)

4 Round Bar

Cut-Off Area

(a)

(b)

62

(c)

(d)

Fig 3-16 Cut-Off Area of (a) 1 Round Bar (b) 2 Round Bar (c) 3 Round Bar and (d) 4 Round

Bar

63

SUM 23 Black Surface Round Bar

Fig 3-17 SUM 23 Black Surface Material

Number 1 2 3

Hardness(HRB) 51 50 51

Yield Stress (MPa) 378 371 369

Tensile Strength (MPa) 467 465 464

Poissonrsquos Ratio 03 016 04

Youngrsquos Modulus (GPa) 215 266 266

Cut-off Area Shrinking () 986 94 848

Elongation () 748 805 761

Table 3-7 Mechanical Properties of SUM 23 Black Surface Material

64

Stress-Strain Diagram

(a)

(b)

65

(c)

Fig 3-18 Stress-Strain Diagrams for (a) 1 Round Bar 2 Round Bar and (c) 3 Round Bar

Cut-Off Surface

(a)

66

(b)

(c)

Fig 3-19 Cut-Off Surface of (a) 1 Round Bar 2 Round Bar and (c) 3 Round Bar

67

342 SUM 43

Fig 3-20 Untreated SUM 43 Untreated Material

Number 1 5

Hardness(HRB) 76 75

Yield Stress (MPa) 572 594

Tensile Strength (MPa) 743 785

Poissonrsquos Ratio 027 029

Youngrsquos Modulus (GPa) 200 202

Cut-off Area Shrinking () 338 2944

Elongation () 857 894

Table 3-8 Mechanical Properties of SUM 43 Untreated

68

Stress-Strain Diagrams

(a)

(b)

Fig 3-21 Stress-Strain Diagrams for SUM 43 (a) 1 Round Bar and (b) 5 Round Bar

69

Cut-Off Area

(a)

(b)

Fig 3-22 Cut-Off Area of SUM 43 (a) 1 Round Bar and (b) 5 Round Bar

70

SUM 43 Nickel Round Bar

Fig 3-23 SUM 43 Nickel Material

Number 4 5

Hardness(HRB) 51 50

Yield Stress (MPa) 1580 1544

Tensile Strength (MPa) 1639 1625

Poissonrsquos Ratio 03 028

Youngrsquos Modulus (GPa) 194 201

Cut-off Area Shrinking () 1697 137

Elongation () 376 265

Table 3-9 Mechanical Properties of SUM 43 Nickel

71

Stress-Strain Diagrams

(a)

(b)

Fig 3-24 Stress-Strain Diagrams for (a) 4 Round Bar and (b) 5 Round Bar

72

Cut-Off Area

(a)

(b)

Fig 3-25 Cut-Off Area of (a) 4 Round Bar and (b) 5 Round Bar

73

SUM 43 Black Surface Material

Fig 3-26 SUM 43 Black Surface Material

Number 3 5

Hardness(HRB) 56 56

Yield Stress (MPa) 1416 1361

Tensile Strength (MPa) 1591 1402

Poissonrsquos Ratio 029 031

Youngrsquos Modulus (GPa) 200 202

Cut-off Area Shrinking () 139 124

Elongation () 24 24

Table 3-10 Mechanical Properties of SUM 43 Black Surface Material

74

Stress-Strain Diagrams

0 2 4 6 8 10 12 14

-200

0

200

400

600

800

1000

1200

1400

1600

1800

應力 (MPa)

應變()

(a)

0 2 4 6 8 10

-200

0

200

400

600

800

1000

1200

1400

1600

應力

(MPa)

位移 ()

(b)

Fig 3-27 Stress-Strain Diagrams for (a) 3 Round Bar and (b) 5 Round Bar

(Note These curves were formulated using Visual Solutions Inc VisSim Software)

75

Cut-Off Area

(a)

(b)

Fig 3-28 Cut-Off Area of (a) 3 Round Bar and (b) 5 Round Bar

76

The force value (N) was retrieved from the Universal Testing Machine

The Poissonrsquos Ratio (ε) is calculated as

ε =

the values for the Poissonrsquos Ratio are in average around 0297

The Youngrsquos Modulus (E) is calculated as

E =

Where

Stress =

Cross-sectional Area =

where D is the Diameter

The value for D was in average around 1258 mm

The values shown by the computer because there is Slippage phenomena between the Clamp and the

specimen will not be taken into consideration for the elongation strain and Youngrsquos modulus and we will

refer to the values that we have meticulously calculated

77

Chapter 4 AR COATING IN DEPTH

41 Experimentrsquos Purpose and Principles

By means of a vacuum chamber and several other instruments we intend to apply Anti-Reflective

Coating using deposition process to a laser diode and in this way reduce its refraction so as to make it

lose less light in the process of amplification and we can control certain wavelengths we want produced

for certain desired applications in our case we are attempting to re-create a Bose-Einstein Condensate

An optimal BEC apparatus is shown in figure 4-1

Fig 4-1 BEC Apparatus

The main point of this experiment is to build a vacuum chamber system attach all the instrumentation

needed (Vacuum pump deposition meter and voltmeter) and use it to apply AR coating to a laser diode

After we have accomplished the AR coating other team will be in charge of designing the BEC apparatus

and use the results of our research

78

42 Experimentrsquos Equipment

421 Vacuum Chamber

For this research we designed a vacuum chamber whose main body is shown in figure 4-2 Its

dimensions are

Width 240 mm

Length 240 mm

Height 200 mm

Outer Diameter 4 in

Inner Diameter 15 in

Fig 4-2 Vacuum Chamber Main Body

The chamber is made up of 6 pass ways pass way A is the connection with the Laser Deposition

Equipment pass way B is the connection with the Turbo Pump and pass way C is for the connection with

the Deposition Source

A

C

B

79

Pass way C is for the deposition source as mentioned above This is a system where a thermal

resistance is heated by passing a high current through it which heats up a filament boat (made of tungsten)

where the material to be evaporated is place We control the temperature as such that the material will

evaporate and the heat will not cause the filament boat to crack

Because P = Isup2 R (where P is power I is current and R is resistance) to avoid the current to flow

where it is not desired we decided that the material for the Thermocouple shown in figure 4-3 should be

Copper ᴓ 63 mm We choose it that way because Copper has very good heat dissipation characteristics

and the resistance value is low It can reduce the value of the current enough to make the thermocouple to

create heat

Fig 4-3 Thermocouple

To the thermocouple we attach the tungsten filament boat We need to take notice of materials to be

used in this design because when using high current the tungsten filament boar will heat up and so the

material must be able to keep up with the heating potential of tungsten and has a low coefficient of heat

dissipation to avoid the tungsten to fail when heating up and therefore not evaporating Considering all

this we decide to use Stainless Steel

Because this clamp will be assembled inside the chamber after many revisions it was determined it

will have the shape shown in figure 4-4

Fig 4-4 Filament Boat Clamp Design

80

For the tungsten filament boat we bought the product from a distributor The dimensions are

Length 100 mm

Width 10 mm

Height 1 mm

Our thermocouple is 15 in but the pass way C is 4 in so we need to attach a Flange that connects

15in to 4in Because these specifications are quite difficult to achieve by Milling we had to use

electrical wire cutting

For the laser clamping system where the laser that is going to be AR coated will be placed will be

connected to pass way A the assembly is shown in figure 4-5 below

Fig 4-5 Cover Assembly

For this design we used an O-ring instead of a gasket so as to save time The design of the assembly

where the laser will be placed is shown in figure 4-6

Fig 4-6 Upper Cover Inner Assembly

D

E

F

81

Point D is the plate in the assembly where the laser diode will be fixed Because of the easy

processing we decide to use Aluminum and it is screwed to the top cover Point E is the connection for

the Quartz crystal resonator and it is designed in the same as point F in this way the results of the quartz

microbalance system will be more accurate in real time Point F is the final resting place for the laser

diode We use a Thor Labs Base with dimensions of ᴓ 9mm and ᴓ 56mm for two different size laser

diodes It just needs to be plugged in for easy installation

From figure 4-6 we know that the system needs signal system connections and because of the

change in temperature inside the chamber this could affect the functioning of the quartz microbalance so

we also need to install water tubes for cooling This is shown in figure 4-7 below

Fig 4-7 Diagram of Upper Cover Connections

In figure 4-8 we show the Feed through connections and their functions

Fig 4-8 Feed through Diagram

82

1 SQM-160 wire 5 Laser Connection 1 (Vin)

2 SQM-160 (G) 6 Laser Connection 2 (G)

3 K-Type-1 7 Laser Connection 3 (PD)

4 K-Type-2 8 Not In Use

The fully assembled chamber is shown in figure 4-9

Fig 4-9 Fully Assembled Chamber

422 Quartz Crystal Microbalance

For measuring the deposition on our target for coating we used the Inficon SQM-160 RateThickness

Monitor It is an easy to use instrument for measuring many types of thin-film coatings as shown in

figure 4-10

(a) Front Panel (b) Back Panel

Fig 4-10 Inficon SQM-160

83

Table 4-1 shows the technical specifications for this equipment

Number of sensors 2 Standard 4 additional optional

Sensor Frequency Range 40 MHz ~ 60 MHz

Reference Frequency Accuracy 002

Thickness Display Resolution 1 Aring

Thickness Resolution 015 Aring (Std) 0037 Aring (Hi Res)

Density of Stored Films 05-9999 gmcc

Tooling 10-399

Z-Factor 010-1000

Final Thickness 0000-9999k Aring

Measurement Period 15 to 2 sec

Simulation Mode Yes

Frequency Mode Yes

Rate Resolution 011 Arings

Dual Crystal Yes

Etch Mode Yes

Crystal Tooling 10-399

Crystal Fail Min Max 40 to 60 MHz 41 to 61 MHz

Power 100-120 200-240~plusmn10 nominal 20W

Operation Environment 0degC ~ 50degC

0 ~ 80 RH non-condensing

0 ~ 2000 meters

Class 1 Equipment

Pollution Degree 2

Rack Dimensions 885mm x 2127mm x 1969mm

Weight 27 kg

Table 4-1 Inficon SQM-160 RateThickness Monitor Specs

84

To the SQM-160 we need to connect an Oscillator We use the Sigma Instruments Remote Oscillator

Ser No 2 268 as shown in figure 4-11

Fig 4-11 Sigma Instruments Remote Oscillator

The connections diagram is shown in figure 4-12

Fig 4-12 SQM-160 Connections Diagram

85

423 Turbo Pump

For our experiments we used the Pfeiffer TCP 015 Electronic Drive Unit shown below in figure 4-13

Table 4-2 shows the technical specifications for this equipment

(a) Front Panel (b) Back Panel

Fig 4-13 Pfeiffer TCP 015 Electronic Drive

Connection Voltage (100V) 90-112

Mains Frequency 5060 Hz

Start-up Current 22 A

Nominal Frequency 1500 Hz

Rotation Speed 10V = 1500Hz plusmn2

Analog Output Current 10 V = 25 A plusmn 5

Rotation Speed Switchpoint 750 Hz

Works Setting 8 min

Permissible Ambient Temperature 0degC ~ 40degC

Dimensions Front Panel 1285mm x 1063mm

Insertion Length 227mm

Weight 27 Kg

Table 4-2 Pfeiffer TCP 015 Electronic Drive Specs

86

The connections diagram is shown in figure 4-14

Fig 4-14Connections Diagram for Pfeiffer TCP 015

To measure the pressure inside the chamber we use the Granville Phillips 375 Convectron Vacuum

Pressure Controller shown in figure 4-15

(a) Front Panel (b) Back Panel

Fig 4-15 Granville Phillips 375 Convectron

87

Its dimensions are shown in figure 4-16

Fig 4-16 Dimensions of Convectron

Table 4-3 shows the technical specifications for this equipment

Table 4-3 Granville Phillips 375 Convectron Vacuum Pressure Controller Specs

88

424 Multimeter

For our experiment we used the Keithley 2000 Digital Multimeter as shown in figure 4-17

(a) Front Panel (b) Back Panel

Fig 4-17 Keithley Model 2000 6-12-Digit Digital Multimeter

Its technical specifications are shown in table 4-4

Table 4-4 Keithley Model 2000 6-12-Digit Digital Multimeter Specs

89

43 Experiment Procedure

1 Connecting together the equipment and the chamber

(1) We first connect the resonator to the thickness monitor and connect the other side to the

chamber

(2) We now connect the flexible tubes to the turbo pump on one side and to the chamber on the

other

(3) We need to check that tubes are tightly connected to avoid any leaks in the vacuum pumping

process which will not allow us to get to our goal of Torr As shown in figure 4-18

(4) Connect the convectron to the system as shown in figure 4-19

Fig 4-18 checking for leaks using alcohol

Fig 4-19 Convectron attached to System

90

(5) Attach the clamps of the Multimeter to the bottom of the chamber as shown in figure 4-20

(6) Place the Quartz crystal in place

(7) Close tight vacuum chamber

(8) Connect all electrical appliances to power source

Fig 4-20 Multimeter Connections

2 Starting up the System

(1) We turn on all the devices as such Check all systems are ready to function Reset all values

that might be left over from previous tests

(2) Start the thickness monitor and set all values for this experiment In our case we got to testing

the system but not actual coating So we used the simulation mode of the thickness monitor as

shown in figure 4-21

Fig 4-21 Simulation Mode

91

(3) Start the turbo pump Make sure the lid on the vacuum chamber is tightly closed

(4) Start convectron and record initial pressure

(5) Start Multimeter and record initial current

3 Coating Process

(1) If we have the deposition material inside the filament boat the power source for the high

current must be started as well

(2) Record all initial values for thickness current pressure

(3) For an ideal experiment we need a thickness of around 101 nm a pressure of Torr and

a current of 300 A

44 Results

From previous experiments we have shown that we can turn a LED into a laser by means of AR

Coating In figure 4-22 shown below we can compare the actual results of a Diode before and after AR

coating From the blue line we can see that when the diode is at a current of 15mA its light will change

from LED to laser and if we look at the red line its critical current is around 30 to 35 mA

Fig 4-22 AR Coating Comparison for Laser Diodes

This means that the light emitted is not as strong as if the diode had been coated because inside the

chamber there must be some excitation first so the reflectivity of both sides inside the diode must be high

So because of the coating in one of the sides we have opened a door and let the light come out so the

critical current is risen as such and will be higher value than that of before the coating

92

In the following figures we can see the difference between before and after coating in a material The

thickness is around 1016 nm for this material

Fig 4-23 Before Coating

Fig 4-24 After Coating

93

Chapter 5 CONCLUSIONS AND RECOMMENDATIONS

51 Conclusions

For the first part of this independent study taking into consideration the data that came out of our

research and that sent by the provider we can say

1 SUM 23 after heat treatment will unexpectedly develop cracking in the middle of the tensile

testing process and suddenly break

2 Itrsquos possible that in the process of heat treatment to the SUM 23 material the treatment was not

uniform and this will create a pre-loaded moment force on one side that pushes on the other side

of the specimen resulting in material deformation

3 In the process of attaching the strain gauges to the materials it is very easy to make errors due to

poor adhesion or sudden removal in the tensile testing process

For our second part of the independent study the following can be made

1 At the beginning of this independent study we had no idea what Bose-Einstein Condensate was

or what was its purpose After much literature we finally comprehended the basic principles to

put into practice for our research

2 Our systemrsquos basic working principles and equipmentrsquos complexity are a little difficult to grasp

but hopefully we were able to understand enough of it

3 Theoretically from relation between the power and current we can know the advantages and

disadvantages of AR Coating

4 We were able to assemble the system and run test on its functions Even though we were able to

do this there is still much more work left to do with this system

52 Recommendations

For the Tensile Testing the following can be said

1 Ask the provider to check on the process of heat treatment on the SUM 23 material and give

them the information we have gathered through our test so they can correct for the mechanical

properties found if any change is needed

2 To avoid the problem of the inaccuracy of the poor adhesion of strain gauges we can attach

multiple strain gauges to the same one specimen so as to correlate data and improve our results

For the AR Coating the following can be said

1 We need to make sure that there are no physical defects on the main body of the chamber so as to

achieve maximum efficiency in the vacuum process If there was then the vacuum will arrive to

certain point and then start to decrease

2 It would be preferable to add some sort of visual aid that will allow the user to check the inside of

the chamber without actually opening it This will help us determine at what times we should

manipulate the current to better evaporate the substrate

94

REFERENCES

[1] A L Window Strain Gauge Technology Elsevier Applied Science London and New York 2nd

Edition 1992

[2] CC Perry and HR Lissner Strain Gauge Primer McGraw-Hill Book Co Inc New York 1955

[3] James W Dally William F Riley McGraw-Hill 1978

[4] University of Colorado Boulder BEC - What is it and where did the idea come from

httpwwwcoloradoeduphysics2000becwhat_is_ithtml

[5] Ultraslow Light amp Bose-Einstein Condensates Two-way Control with Coherent Light amp Atom

Fields Harvard Hau Lab Dr Lene Vestergaard Hau Optics amp Photonics News 16 1995

[6] The Art of Taming Light Ultra-slow and Stopped Light Harvard Hau Lab Dr Lene

Vestergaard Hau Europhysics News 2004

[7] Nonlinear Optics Shocking Superfluids Harvard Hau Lab Dr Lene Vestergaard Hau Nature

Physics 2007

[8] Model P3 Strain Indicator and Recorder Instruction Manual Vishay Micro-Measurements 2005

[9] Granville-Phillips Series 375 Convectron Vacuum Gauge Controller Instruction Manual Brooks

Automation 2008

[10] Effect of Film Thickness on the Validity of the Sauerbrey Equation for Hydrated Polyelectrolyte

Films Vogt Lin Wu White 2004

[11] Quartz Crystal Microbalance Study of DNA Immobilization and Hybridization for DNA Sensor

Development Chang Zhao 2008

[12] Installation of Strain Gages with SR-4 PrecoatAdhesive Vishay Micro-Measurements 2005

[13] Strain Gauge Measurement ndash A Tutorial National Instruments 1998

[14] Correlation between Vickers Hardness Number and Yield Stress of Cold-Formed Products

Yavuz Tekkaya

[15] httpsenwikipediaorg

Page 6: PC Hinge Materials Testing and AR Laser Diode Coating

6

323 Strain Gaugehelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 45

324 Specimen Measurementshelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 47

33 Experiment Procedurehelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 47

34 Resultshelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 54

341 SUM 23helliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 55

342 SUM 43helliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 67

CHAPTER 4 AR Coating in depthhelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 77

41 Experimentrsquos Purpose and Principleshelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 77

42 Experimentrsquos Equipmenthelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 78

421 Vacuum Chamberhelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 78

422 Quartz Microbalancehelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 82

423 Turbo Pumphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 85

423 Multimeterhelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 88

43 Experiment Procedurehelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 89

44 Resultshelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 91

CHAPTER 5 Conclusions and Recommendationshelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 93

51 Conclusionshelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 93

52 Recommendationshelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 93

REFERENCEShelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 94

7

LIST OF TABLES

Table 2-1 Rockwell Hardness Test Scalehelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 20

Table 2-2 Z-Ratios for Different Materialshelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 33

Table 2-3 Classifications of Vacuumhelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 39

Table 3-1 Chun Yen Testing Machine Specshelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 42

Table 3-2 Vishay Micro-Measurements Model P3 Strain Indicator and Recorder Specshelliphelliphelliphelliphelliphellip 44

Table 3-3 Specifications for Round Barhelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 47

Table 3-4 Specifications for Strain Gaugehelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 48

Table 3-5 Mechanical Properties of SUM 23 Untreatedhelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 55

Table 3-6 Mechanical Properties of SUM 23 Nickelhelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 58

Table 3-7 Mechanical Properties of SUM23 Black Surface Materialhelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 63

Table 3-8 Mechanical Properties of SUM 43 Untreatedhelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 67

Table 3-9 Mechanical Properties of SUM 43 Nickelhelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 70

Table 3-10 Mechanical Properties of SUM 43 Black Surface Materialhelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 73

Table 4-1 Inficon SQM-160 RateThickness Monitor Specshelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 83

Table 4-2 Pfeiffer TCP 015 Electronic Drive Specshelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 85

Table 4-3 Granville Phillips 375 Convectron Vacuum Pressure Controller Specshelliphelliphelliphelliphelliphelliphelliphelliphellip 87

Table 4-4 Keithley Model 2000 6-12-Digit Digital Multimeter Specshelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 88

8

LIST OF FIGURES

Fig 1-1 Notebook Computer Hingehelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 11

Fig 1-2 Basic Structure of Laserhelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 11

Fig 1-3 Comparison between LED and Laser Diodehelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 12

Fig 1-4 External Cavity Designhelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 12

Fig 2-1 Stress-Strain Curvehelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 14

Fig 2-2 Stress-Strain Curve Comparison on Metalshelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 15

Fig 2-3 Basic Structure of Strain Gaugehelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 17

Fig 2-4 Strain Gauge Attached to Wheatstone Bridgehelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 18

Fig 2-5 Brinell Indentationhelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 18

Fig 2-6 Brinell Hardness Testerhelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 18

Fig 2-7 Rockwell Indentationhelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 19

Fig 2-8 Rockwell Hardness Testerhelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 19

Fig 2-9 Vickers Indentationhelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 22

Fig 2-10 Vickers Hardness Testerhelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 22

Fig 2-11 Bose-Einstein Condensate at different scaleshelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 23

Fig 2-12 Super Conductorhelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 24

Fig 2-13 Simple Model for Light in Glass Mediumhelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 25

Fig 2-14 Simple Model for Light in Glass Medium after AR Coatinghelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 26

Fig 2-15 Light Passing through AR Coating and Glasshelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 27

Fig 2-16 Lens without and with AR Coatinghelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 27

Fig 2-17 Laser Diodehelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 28

Fig 2-18 Tunable Laser Basic Configurationhelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 28

Fig 2-19 Light Spectrumhelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 29

Fig 2-20 Front and Back Panel of SQM-160helliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 29

Fig 2-21 QCM Crystalshelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 31

Fig 2-22 SQM-160 Oscillatorhelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 31

Fig 2-23 Oscillator Circuithelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 32

Fig 2-24 Vacuum Evaporation Systemhelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 39

Fig 2-25 Turbo Pumphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 39

Fig 2-26 Control and Measurement Equipmenthelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 40

Fig 2-27 Complete Systemhelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 40

Fig 3-1 Universal Testing Machinehelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 41

Fig 3-2 Diagram for System Connectionshelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 42

Fig 3-3 Input Connections for Strain Gaugehelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 43

Fig 3-4 Vishay Micro-Measurements Model P3 Strain Indicator and Recorderhelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 43

Fig 3-5 Inner Connectionshelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 45

Fig 3-6 Tensile Specimenhelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 47

Fig 3-7 Actual Tensile Specimenhelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip47

Fig 3-8 Other Materials Usedhelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 48

Fig 3-9 Specimen-Strain Gauge Processhelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 49

Fig 3-10 Specimen-Tensile Testing Processhelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 53

9

Fig 3-11 SUM 23 Untreated Materialhelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 55

Fig 3-12 Stress-Strain Diagrams for 7 and 10 Round Barhelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 56

Fig 3-13 Cut-Off Area of 7 and 10 Round Barhelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 57

Fig 3-14 SUM 23 Nickel Materialhelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 58

Fig 3-15 Stress-Strain Diagrams for 1 2 3 and 4 Round Barhelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip60

Fig 3-16 Cut-Off Area of 1 2 3 and 4 Round Barhelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 62

Fig 3-17 SUM 23 Black Surface Materialhelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 63

Fig 3-18 Stress-Strain Diagrams for 1 2 and 3 Round Barhelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 65

Fig 3-19 Cut-Off Area of 1 2 and 3 Round Barhelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 66

Fig 3-20 SUM 43 Untreated Materialhelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip67

Fig 3-21 Stress-Strain Diagrams for 1 and 5 Round Barhelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 68

Fig 3-22 Cut-Off Area of 1 and 5 Round Barhelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 69

Fig 3-23 SUM 43 Nickel Materialhelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 70

Fig 3-24 Stress-Strain Diagrams for 4 and 5 Round Barhelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 71

Fig 3-25 Cut-Off Area of 4 and 5 Round Barhelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 72

Fig 3-26 SUM 43 Black Surface Materialhelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 73

Fig 3-27 Stress-Strain Diagrams for 3 and 5 Round Barhelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 74

Fig 3-28 Cut-Off Area of 3 and 5 Round Barhelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 75

Fig 4-1 BEC Apparatushelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 77

Fig 4-2 Vacuum Chamber Main Bodyhelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 78

Fig 4-3 Thermocouplehelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip79

Fig 4-4 Filament Boat Clamp Designhelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 79

Fig 4-5 Cover Assemblyhelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 80

Fig 4-6 Upper Cover Inner Assemblyhelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 80

Fig 4-7 Diagram of Upper Cover Connectionshelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 81

Fig 4-8 Feed Through Diagramhelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 81

Fig 4-9 Fully Assembled Chamberhelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 82

Fig 4-10 Inficon SQM-160helliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 82

Fig 4-11 Sigma Instruments Remote Oscillatorhelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 84

Fig 4-12 SQM-160 Connections Diagramhelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 84

Fig 4-13 Pfeiffer TCP 015 Electronic Drivehelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 85

Fig 4-14 Connections Diagram for Pfeiffer TCP 015helliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 86

Fig 4-15 Granville Phillips 375 Convectronhelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 86

Fig 4-16 Dimensions of Convectronhelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 87

Fig 4-17 Keithley Model 2000 6-12-Digit Digital Multimeterhelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 88

Fig 4-18 Checking for Leaks Using Alcoholhelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 89

Fig 4-19 Convectron Attached to Systemhelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 89

Fig 4-20 Multimeter Connectionshelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 90

Fig 4-21 Simulation Modehelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 90

Fig 4-22 AR Coating Comparison for Laser Diodeshelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 91

Fig 4-23 Before AR Coatinghelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 92

Fig 4-24 After AR Coatinghelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 92

10

Chapter 1 INTRODUCTION

11 Motivation and Background

In response that new generation computers are gradually reducing their size the diameter of

the structures of the hinges used by NB computers must also follow but the hinge strength may

also become smaller due to the reduction of diameter and result in the phenomenon of

insufficient strength In addition the disk-type spring that is source of the torque may also be

insufficient due to the narrowing of the structure Therefore it is necessary to direct a structural

analysis of the hinge for the existing laptops so that we can identify the stress concentration

point The stress concentration point is usually the point where material damage behavior is

encountered the easiest and if we can find the point where breaking occurs most often we can

improve the design of the existing structure to enhance the strength of the hinge structure

Second the structure of the hinge is too complicated the traditional mechanics of materials

analysis methods and formulas are no longer suitable for analysis of a wide arrange of hinge

design In recent years finite element analysis methods have been widely applied in various

fields such as electronics machinery aviation and so on

Therefore to meet the need of the industry and with the purpose of reducing design time

how to design a notebook computer hinge without compromising mechanical stability and

materialrsquos hardness which will operate equally under equal conditions In other words be able to

meet the needs of the size decreasing NB computers market as the needs for this kind of

accessories will increase in the near future If we take into consideration the traditional ways of

design we seek to reduce the costs of use of machinery and molding by applying Finite Element

Analysis methods to our study and also increase the flexibility of designing methods

The second project was brought in by Prof Chuang and it is to help in the further research of

the Bose-Einstein condensate This is a state of matter of a dilute gas weakly interacting bosons

(subatomic particles that obey the Bose-Einstein statistics) confined in an external potential and

cooled down to temperatures very near absolute zero (0 K or -27315deg C) Under these conditions

a large number of bosons occupy the lowest quantum state of the external potential at which

point quantum effects become apparent at macroscopic scale This state of matter was predicted

by Satyendra Nath Bose and Albert Einstein in 1924~1925 Then 70 years later the 1st gaseous

condensate was produced by Eric Cornell and Carl Wieman in 1995 at the University of

Colorado (Boulder) NIST-JILA lab and because of this along with Wolfgang Ketterle of MIT

they received the 2001 Nobel Prize in Physics

11

We wish to investigate the properties of Anti Reflecting Coating on laser diodes Hopefully

we will be able to achieve the desired effect of reducing the surface reflection coefficient and

find applications for it

12 Research Objective

We wish to analyze the normal composition of the notebook computerrsquos hinge at which

point in the assembly is clearly the weakest and at this time in the assembly the strength and

durability are influenced The main point is to see if we can affect the normal operation and work

life

The objective of this thesis is to present the results of the material properties under tensile

testing find the mechanical properties and after using finite element analysis determine what

material is the best for our purposes

Fig 1-1 Notebook Computer Hinge

For our second research we wish to produce and analyze laser diodes with anti-reflective

coating and test its properties and applications

When semi-conductor laser has been submitted to current it will produce resonance inside it

and light will be stimulated to come out Please refer to figure 1-2 for the basic structure of a

laser

Fig 1-2 Basic Structure of a Laser

1 Gain Medium

2 Laser Pumping Energy

3 High Reflector

4 Output Coupler

5 Laser Beam

12

But when the laser diode generates light but the laser diode canrsquot produce light on itself it

must wait for the current to be higher than certain value which is called the critical current Until

the light goes over this threshold then it is considered laser light if not it is just considered as a

common LED light source Please refer to figure 1-3

Fig 1-3 Comparison between LED and Laser Diode

As we can see from figure 1-3 all of the light that goes over the critical current is laser light

and so the external cavity semi-conductor laser that we built needs Anti-Reflective Coating

because the method we want to use needs an external cavity laser that has been covered with AR

Coating and a Diffraction Grating We use this configuration first by shooting the laser to the

grating and this will be shot back to the laser creating the external resonance cavity which is

shown in figure 1-4

Fig 1-4 External Cavity Design

13

Two configurations are shown the Littrow Configuration and the Littman-Metcalf

Configuration The Littrow configuration contains a collimating lens and a diffraction grating as

the end mirror The first order diffracted beam provides optical feedback to the laser diode which

has AR Coating The emission wavelength can be turned by rotating the diffraction grating A

disadvantage is that it also changes the direction of the output beam

In the Littman-Metcalf configuration the grating orientation is fixed and an additional mirror

is used to reflect the first order beam back to the laser diode The wavelength can be turned by

rotating that mirror This configuration offers a fixed direction of the output beam and also tends

to exhibit smaller line width as the wavelength selectivity is stronger A disadvantage is that

zero order reflection of the beam reflected by the tuning mirror is lost so that the output power is

less than that of a Littrow laser

13 Methodology

The aim of this research is to find the mechanical properties of materials after being

subjected to tensile testing through finite element analysis observations and determine what

material is best for our purposes taking into consideration the strength and durability of the

material among other properties to find use and applications for the AR coated laser diodes to

further improve the grasp of the Bose-Einstein condensation working principles

14 Organization of the Thesis

The research paper includes five chapters

1 Chapter 1 explains the motivation background objective and methodology of this study

2 Chapter 2 explains the working principles and basic knowledge needed to understand this

study

3 Chapter 3 explains the tensile testing in detail steps methods and results

4 Chapter 4 explains the AR coating in detail steps methods and results

5 Chapter 5 is the conclusions taken from the results shown in chapter 3 and 4 and

recommendations done after arranging and critical thinking

14

Chapter 2 BASICS THEORIES

21 Tensile Testing

After a specimen is tested with the use of tensile testing we can get the Stress-Strain Curve using the

relation between tension and displacement Typical curves are shown in Fig 2-1

(a) Ductile materials (b) Brittle materials

Fig 2-1 Stress-Strain Curve

The curve is unique for each material and is found by recording the amount of deformation at distinct

intervals of tensile or compressive loads Thanks to the use of the Stress-Strain curve we can get very

useful information such as

211 Youngrsquos Modulus (E)

As shown in Fig 2-1 as long as the external load is not greater than the Proportional Limit the Stress

(σ) and Strain (ε) remain as a linear relation fulfilling Hookersquos Law

σ = Eε

The slope is the constant factor the inverse of the modulus of elasticity E also called Youngrsquos

modulus When the external load goes over the proportional limit the stress-strain relationship doesnrsquot

follow the linear relation anymore but the deformation remains flexible When the load is released the

deformation is completely eliminated and the specimen goes back to its original state This is called

15

Elastic Deformation When the external load goes over the Elastic limit only then does the specimen

presents Plastic Deformation This type of deformation which is irreversible even when the load is

removed comes after the material does under elastic deformation so this means the object will first come

part way to its original shape Common metals and ceramics have roughly the same elastic limits

212 Yield Strength and Yield Point

Some materials display very evident yield phenomena while some materials donrsquot as shown in Fig

2-2 After we exceed the elastic limit if we continue to exert load when we arrive to a certain value

which differs under different materials and external conditions there is sudden decrease in stress and this

is called the Yield Strength and can be defined as the stress at which a material begins to deform

plastically using the equation

σyield =

Where P is the tension force and Ao is the original cut-off area

The stress remain at a certain value after the decrease but the strain increases this phenomena can be

easily appreciated when studying the behavior of common Carbon Steel Fig2-2 (a) but most metals (like

Aluminum Copper or High Steel Carbon) donrsquot display this kind of behavior as shown in Fig 2-2 (b)

Arriving to this point is very difficult and the most commonly used method for this is to add a 02 or

0002 offset yield strength to the curve This point is held constant on the strain axis of the curve and

from the 0002 position we draw a straight line parallel to the linear relationship line the point at where

this line and the stress-strain curve intercept is the point we take as the 02 offset yield strength

(a)Evident (b) Non-evident

Fig2-2 Stress-Strain Curve Comparison on Metals

16

213 Ultimate Tensile Strength and Breaking Strength

After materials undergo yield they keep lending strength and hardening phenomena occurs (work

hardening) on the material and the external load increases When it has reached the highest point this is

called the Ultimate Tensile Strength (UTS) as shown in Fig2-1 The UTS is defined as

σUTS =

Where Pmax is the load at the materialrsquos ultimate tensile strength point and Ao is the original cut-off

area For brittle materials the ultimate tensile strength is the most important mechanical property for

ductile materials the ultimate tensile strength is not commonly used for industrial and designing purposes

because upon arriving to this value the material already has forgone great plastic deformation After the

specimen goes through UTS there will be necking phenomena which is a mode of tensile deformation

where relatively large amounts of strain localize disproportionately in a small region of the material It

results from instability during tensile deformation when a materialrsquos cross-sectional area decreases by a

greater proportion than the material strain hardens The specimen continues to elongate until it finally

breaks and the load at this point is called Breaking Strength The breaking strength is defined as the

greatest stress in tension that a material is capable of withstanding without rupture

Where Pf is the load at the materialrsquos breaking strength point and Ao is the original cut-off area

214 Poissonrsquos Ratio (ν)

For elastic deformation when materials are compressed in one direction they tend to expand in the

other two directions perpendicular to the direction of compression This is called the Poissonrsquos Effect

The Poison Ratio is a measure of the Poissonrsquos effect It is the ratio of the fraction of expansion divided

by the fraction of compression for small values of these changes

ν=-

215 Strain Gauge Basic Principles

The strain gauge is a device used to measure the strain of an object Itrsquos an elongated metal resistor

which is attached to the specimen being measured and when the specimen is under strain and starts to

deform the strain gauge will have a change in the resistance With the change in value we can calculate

the elementrsquos strain or elastic modulus and the Poissonrsquos ratio

It takes advantage of the physical property of electrical conductance and its dependence on the

conductorrsquos geometry When the electrical conductor (the specimen being tested) is stretched within the

limits of elasticity such that it does not break or deform plastically it will become narrower and longer

17

which increases the electrical resistance through-out From the measured resistance of the strain gauge

the amount of stress may be inferred by using the relations

R=

Where R is the original resistance value is the electrical resistivity lo is the original length of the

conductor and Ao is the original cross sectional area of the conductor If after the application of tension

the change in length is Δl let the length of the specimen be l = l + Δlo and the tension is the same

through-out So

And the resistance is

The Gauge Factor is the ratio of relative change in electrical resistance to the mechanical strain in

other words it is the relative change in length It is defined as

The strain gauge was invented in 1938 by Edward E Simmons and Arthur C Ruge and the most

common type consists of an insulating flexible backing which supports a metallic foil usually made of a

brass-nickel alloy It is attached to the specimen by a suitable adhesive As the object is deformed the foil

also deforms and this causes the electrical resistance to change Then this is usually measured using a

Wheatstone bridge shown below and is related to the strain by the Gauge Factor

Fig2-3 Basic Structure of Strain Gauge

18

Fig 2-4 Strain gauge attached to Wheatstone bridge

22 Hardness Testing Basic Principles

221 Brinell Scale BHN

The Brinell Scale characterizes the indentation hardness of materials through the scale of penetration

of an indenter loaded on a material specimen The typical test uses a 10mm diameter steel ball as indenter

(usually of value equal to BHN450) with a 29kN force For softer materials smaller force is used The

indentation is measured and BHN is calculated using the relation

BHN =

radic

Where F is the applied force usually within the range of 100 250 500 750 1000 1500 2000 2500

and 3000 kgf D is the diameter of indenter usually within the range of 5mm or 10mm plusmn0005 margin

and d is the diameter of indentation usually around 2mm Its units are of Kgmmsup2 but are not normally

written

First proposed by Swedish engineer Johan August Brinell in 1900 it was the first widely used and

standardized hardness test in engineering and metallurgy although the large size of indentation and

possible damage to specimen limits its usefulness

Fig 2-5 Brinell Indentation Fig2-6 Brinell Hardness Tester

19

222 Rockwell Scale HR

The Rockwell scale is a hardness scale based on the indentation hardness of a material The Rockwell

test determines the hardness by measuring the depth of penetration of an indenter under a large load

compared to the penetration made by a preload The indenter is forced into the specimen under a

preliminary load When equilibrium is reached a measuring device follows the movements of the

indenter and responds to changes in depth of penetration of the indenter While the preload is still being

applied additional major load is applied resulting in increased penetration When equilibrium is reached

again the major load is removed but the preload is maintained Removing the major load allows partial

recovery and reduces the depth of penetration The permanent increase in depth of penetration resulting

from the application and removal of the major load is used to calculate the Rockwell number using the

relation

HR = E ndash e

Where E is a constant depending on the form of the indenter 100 units for diamond indenter and 130

units for steel ball indenter e is the permanent increase in depth of penetration due to the major load

measured in units of 0002mm

Fig 2-7 Rockwell Indentation

When testing materials indentation hardness is related linearly to the tensile strength The important

relation permits economically important nondestructive testing of bulk metal deliveries with lightweight

equipment like the Rockwell tester shown below in figure 2-7

Fig 2-8 Rockwell Hardness Tester

20

There are different scales denoted by a single letter that use different loads or different indenters

The result is a dimensionless number denoted as HR X where X will be the letter denoting the scale as

shown below in table 2-1

Table 2-1 Rockwell Hardness Test Scale

Differential depth hardness measurement was first conceived in 1908 by Viennese professor Paul

Ludwik It eliminated the errors associated with the mechanical imperfections of the system such as

backlash and surface imperfections in the specimen Rockwell testing has an advantage over Brinell

testing because the latter was slow itrsquos not useful on fully hardened steel and left too large an impression

to be considered nondestructive

The tester was co-invented by Hugh M Rockwell and Stanley P Rockwell The requirement for this

tester was to quickly determine the effects of heat treatment on steel bearing races

21

223 Vickers Hardness Test HV

This is a type of microindentation hardness test where a diamond indenter of specific geometry is

impressed into the surface of the test specimen using a known applied force ranging from 10 to 1000

grams This type of tests usually has forces of 2N and produce indentations of about 50μm They can be

used to observe changes in hardness on the microscopic scale It is difficult to standardize the

microhardness measurements because it has been found that the microhardness of almost any material is

higher than its macrohardness The values also vary with load and work-hardening effects of materials

The Vickers test is often easier to use than other hardness tests because the required calculations are

independent of the size of the indenter and the indenter can be used for all materials It can be used for all

metals and has one of the widest scales among hardness tests The unit of the Vickers test is denoted as

HV and can be converted to units of Pascal (Pa) but it is not a measurement of pressure The hardness

number is determined by the load over the surface area of the indentation and not the area normal to the

force

A square-based pyramid shaped diamond is use as the indenter It has been established that the ideal

size of a Brinell impression was 38 of the ball diameter As two tangents to the circle at the ends of a

chord 3d8 long intersect at 136plusmn05deg it was decided to use this as the angle of the indenter giving an

angle to the horizontal plane of 22deg on each side The HV number is determined by the ratio FA where F

is the force applied to the diamond in kgf and A is the surface area of the resulting indentation in mmsup2 A

can be determined by the relation

A =

Where A is the surface area of indentation and d is the average length diagonal left by the indenter

This can be approximated as

A =

Then the Vickers Number is

HV =

=

Vickers hardness number is reported as xxxHVyy or xxxHVyyzz (if duration of applied force differs

from 10s to 15s) where xxx are replaced by the hardness number yy is the load in kg and zz indicates

loading time The values are generally independent of test force

The test was developed in 1921 by Robert L Smith and George E Sandland at Vickers Ltd as an

alternative to Brinell method to measure the hardness of materials

22

Fig 2-9 Vickers Indentation Fig 2-10 Vickers Hardness Tester

23 AR Coating

231 Bose-Einstein Condensate

The Bose-Einstein Condensate or BEC is a state of matter of a dilute gas of bosons cooled to

temperatures very near absolute zero around 0K or -27315degC Under such conditions a large fraction of

the bosons occupy the lowest quantum state where the quantum effects become apparent on a

macroscopic scale This gave birth to the Bose-Einstein Statistics which are the rules that govern the

behavior at this state It is one of the two possible ways in which a collection of indistinguishable particles

may occupy a set of available discrete energy states The aggregation of particles in the same state

accounts for the cohesive streaming of laser light and the frictionless creeping of superfluid helium (an

application discussed later) Bose and Einstein recognized that a collection of identical and

indistinguishable particles can be distributed this way This theory applies only to those particles not

limited to single occupancy of the same state particles that do not obey the Pauli Exclusion Principle

restrictions Such particles are the Bosons named after the statistics that correctly describe their behavior

This phenomenon was first predicted by Satyendra Nath Bose around 1924 when he considered how

groups of photons behave He then asked Albert Einstein for help publishing his discoveries to which

Einstein agreed and gave follow up supporting these findings The resulting efforts became the concept of

a Bose gas governed by the Bose-Einstein Statistics described above Einstein demonstrated that cooling

bosonic atoms to a very low temperature would cause them to condense into the lowest accessible

quantum state resulting in a new form of matter

The first gaseous condensate we produced by Eric Cornell and Carl Wieman at the University of

Colorado at Boulder NIST ndash JILA lab sung a gas of rubidium atoms cooled to 170 nK which earned

them the 2001 Nobel Prize in physics together with Wolfgang Ketterle from MIT The transition to BEC

occurs below a critical temperature which for a uniform three dimensional gas consisting of

non-interacting particles with no apparent internal degrees of freedom is given by

23

Tc =

(

)

asymp 33125

Where Tc is the critical temperature n is the particle density m is the mass per boson h is the

reduced Planck constant k is the Boltzmann constant and ζ is the Riemann zeta function

There are two classes of elementary particles defined by whether their quantum spin is a nonnegative

integer or an odd half integer A Bose-Einstein Condensate is shown below in figure 2-11

Fig 2-11 Bose Einstein Condensate at different scales

Bosons are the particles whose quantum spin is a nonnegative integer (s = 0 1 2 etc) Examples of

bosons include fundamental particles (Higgs Boson Photons W and Z Bosons Gluons Gravitons etc)

composite particles (Mesons Hadrons Nuclei and Atoms of Carbon-12 and Helium-4) and

quasi-particles Bosons are considered force carrier particles The Bosons differ from Fermions in that

there is no limit to the number that can occupy the same quantum state This is called the Pauli Exclusion

Principle

The Pauli Exclusion Principle says that no two identical fermions may occupy the same quantum state

simultaneously in other words this means that the total wave function for two identical fermions is

anti-symmetric with respect to exchange of the particles This means that no two electrons in a single

atom can have the same four quantum numbers

Fermion is any particle characterized by Fermi-Dirac Statistics and follows the Pauli Exclusion

Principle described above Quarks Leptons and composite particles (Hadrons Nuclei and Atoms of

Carbon-13 and Helium-3) made of an odd number of these are considered Fermions It can be an

elementary particle such as the electron or a composite particle such as the protons Following the Pauli

24

Exclusion Principle only one fermion can occupy a particular quantum state at any given time If multiple

fermions have the same spatial probability distribution then at least one property of each fermion must be

different Fermions are usually associated with matter because composite fermions are key building

blocks of matter (neutrons and protons)

Fermionsrsquo behavior by the Fermi-Dirac Statistics which describes the energies of single particles in a

system comprising of many identical particles It applies to identical particles with half-odd integer spin

in a system of thermal equilibrium The particles in the system are assumed to have negligible mutual

interaction This allows the many-particle system to be described in terms of single-particle energy states

The result is the Fermi-Dirac distribution of particles over these states and includes the condition that no

two particles can occupy the same state which has considerable effect on the properties of the system

In quantum mechanics the position of an object is uncertain An object has a definite probability of

being at any given point in space This probability is encoded in the wave function mentioned earlier If

one concentrates a large number of identical bosons in a small region then it is possible for their wave

functions to overlap so much that the bosons lose their identity When this happens thatrsquos a Bose-Einstein

Condensate It is only possible at very low temperatures because at high temperatures the individual

bosons have small wave functions and move rapidly which causes them to fly apart

For now applications are still restricted because there are still some setbacks regarding BECs They

are extremely fragile they are being produced in small quantities with just a few million atoms at a time

and finally they can only be made from certain types of atoms Some examples are the atom laser Ketterle

in which a conventional light lase emits a beam of coherent photons this means they are all in phase and

can be concentrated to an extremely small bright spot BECs can slow down light as demonstrated by

Prof Lene Hau PhD in 2001 by the use of a superfluid [7] These manipulations could develop into

new types of telecommunications technology optical storage and quantum computing

BECs are related to super-fluidity and super-conductivity Super-fluidity is the state of matter in

which the behavior is that of a fluid with zero viscosity It was discovered in liquid helium but now it has

applications in astrophysics high-energy physics and theories of quantum gravity

Super-conductivity is a phenomenon of exactly zero electrical resistance and expulsion of magnetic

fields occurring in certain materials when cooled below a characteristic critical temperature A

super-conductor is shown below in figure 2-12

Fig2-12 Super Conductor

25

232 AR Coating Basic Principles

Anti-reflective (AR) coating is a type of optical coating applied to the surface of lenses and other

optical devices (in our case we planned to apply it to a laser diode) to reduce reflection This improves

the efficiency of the system since less light is lost The primary benefit is the elimination of the reflection

itself

When light the medium (glass) it will produce reflection if 100 of the light comes from the air and

enters the glass because therersquos a difference between the index of refraction some of the light will go out

and when the light is coming out of the glass into the air once again because of the difference between

index of refraction some of the light wonrsquot be able to pass through the medium

When the light makes the first trip into the glass there was a loss of about 4 in the reflection and

when the light makes the trip back outside there was another loss of about 4 so when we assume that

100 of the light interacts with the medium actually therersquos just about 92 acting (we neglect the light

absorbed by the glass around 05) To illustrate this idea please refer to figure 2-13

Fig 2-13 Simple Model for Light in Glass Medium

When we apply the AR Coating the light that enters will only have a loss of about 05 and when

making the trip back outside again only 05 of light is loss so we get the result of increasing the light

passing through up to 99 (again neglecting the light absorbed by the glass around 05) To illustrate

this idea please refer to figure 2-14

26

Fig 2-14 Simple Model for Light in Glass Medium after AR Coating

The AR Coating can reduce reflection of incoming light In the case that light hits perpendicular to

the surface of the medium the intensity of the reflection can be calculated using the Reflection

Coefficient

Where n0 and ns are the refractive indices of the first and second media respectively The value of R

varies from 0 (no reflection) to 1 (all light reflected) and is usually quoted as a percentage

Complementary to R is the transmission coefficient or Transmittance If absorption and scattering are

neglected then the value of Transmittance is always 1-R then if a beam of light with intensity I is

incident on the surface a beam of intensity RI is reflected and a beam with intensity TI is transmitted to

the medium

The optimal value is called the Optimal Index of Refraction and is described as

For glass with ns around 15 in air (n0 around 10) then the optimum refractive index will be n1 =

1225

To reduce the refraction in this case we now mean the one that is produced inside the chamber of the

Laser diode the easiest way is to apply a low reflectivity AR coating on the surface of the laser To

measure the appropriate thickness of the coating layer we can use the equations described above By

applying a coat exactly

thickness film we can assure that a certain wavelength is transmitted The

27

reflected waves from the back of the glass medium will be half a wavelength out of phase So they

interfere destructively Because all reflected waves are interfered the maximum amount of light passes

through the coating Please refer to figure 2-15 to illustrate this idea

Fig 2-15 Light Passing through AR Coat and Glass

The most common process to attain this final product is by vacuum deposition For the best coating

results we need to lower the pressure inside the vacuum system to torr

Fig 2-16 Lens without (Top) and With (Bottom) AR Coating

28

233 Laser Diode Basic Principles

A laser diode is a laser whose active medium is a semiconductor similar to that found in

light-emitting diodes (LEDs) Please refer to figure 2-17 The most common type of laser diode is formed

from a p-n junction and powered by injected electric current

Fig 2-17 Laser Diode

Laser diodes are formed by doping a very thin layer on the surface of a crystal wafer The crystal is

doped to produce the n-type region and a p-type region one above the other

By referring to figure 1-2 we can see the basic structure of a working laser When the laser diode has

a current passing through it the light will get excited inside its gain medium and then will start to

resonate this process is called pumping The current exceeds the critical current and then it comes out as

laser light Please refer to figure 1-3 Since we use an external cavity laser we need to apply the AR

coating to the diode and adjust a diffraction grating The laser light comes out the diode and bounces on

the grating making the resonance externally and this becomes the ldquocavityrdquo as shown in figure 2-18

Fig 2-18 Tunable Laser Basic Configuration

29

The most important feature of the external cavity laser is that we can adjust the wavelength easily just

by changing the diffraction gratingrsquos angle and in the end this is the output wavelength of the laser For

different wavelengths there will be different levels of visible light as shown in figure 2-19

Fig 2-19 Light Spectrum

234 Quartz Microbalance System

A Quartz Crystal Microbalance is an instrument that measures a mass per unit area by measuring the

change in frequency of a quartz crystal resonator The resonance is disturbed by the addition or removal

of a small mass due to oxide growthdecay or film deposition (which is the case in our study) at the

surface of the acoustic resonator The QCM can be used under vacuum in gas phase and more recently in

liquid environments It is useful for monitoring the rate of deposition in thin film deposition systems

under vacuum Frequency measurements are easily made with high precision

For our research we used the Sigma Instruments SQM-160 RateThickness Monitor shown in figure

2-20

Fig 2-20 Front and Back Panels of SQM-160

30

The microbalance uses Quartz as the resonator Quartz is one member of the family of crystals that

experience the Piezoelectric Effect

Piezoelectricity is the charge that accumulates in certain solid materials in response to applied

mechanical stress It means electricity resulting from pressure It was discovered in 1880 by Jacques and

Pierre Curie It is understood as the linear electromechanical interaction between the mechanical and the

electrical state in crystalline materials with no inversion symmetry It is a reversible process in that

materials exhibiting direct piezoelectricity also exhibit the reverse This means that the internal generation

of electrical resulting from applied mechanical force and vice versa

By using the piezoelectric effect we can probe as an acoustic resonance by electrical means Applying

alternating current to the quartz crystal induces oscillations This creates a shear wave We can use these

qualities to determine the resonance frequency at high accuracy

The frequency of oscillation of the crystal is partially dependent in the thickness of the crystal During

normal operation all the variables are held constant so a change in thickness correlates directly to a

change in frequency As mass is deposited or etched away the thickness increases or decreases and so the

frequency of oscillation changes accordingly With some simplifying assumptions the frequency change

can be quantified and correlated precisely to the mass change using the Sauerbreyrsquos Equation

Developed by G Sauerbrey in 1959 it is a method for correlating changes in the oscillation

frequency of a piezoelectric crystal with the mass deposited on it It is defined as below

Where f0 is the Resonant frequency Δf is the Frequency change Δm is the mass change A is the

piezoelectrically active area of the crystal q is the Density of quartz (2648 gcmsup3) and μq is the Shear

modulus of quarts(2947x gcmssup2)

Because the film is treated as an extension of thickness Sauerbreyrsquos equation only applies to systems

in which the following 3 conditions are met

Deposited mass must be rigid

Deposited mass must be distributed evenly

The frequency change

lt002

If the change is greater than 2 the Z-match method must be used to determine the change in mass

It is defined as

Where fL is the frequency of the loaded crystal fU is the resonant frequency Nq is the frequency

constant (1668x HzAring) Δm is the mass change A is the piezoelectrically active area of the crystal

31

q is the density of quartz Z is the method constant f is the density of film μq Is the shear modulus of

quarts and μf is the shear modulus of film

The Sauerbrey equation cannot be applied to systems under liquid medium

The crystals are seed crystals plated with gold on both top and bottom for applications A crystal is

shown in figure 2-21 The QCM consists of a thin piezoelectric plate with electrodes evaporated on both

sides Due to the piezoelectric effect AC voltage across the electrodes induces a shear deformation and

vice versa The electromechanical coupling provides a simple way to detect an acoustic resonance by

electrical means

The Z also called Z-factor is a constant value for different materials and it is shown together with the

density of different materials in table 2-2 below

Fig 2-21 QCM Crystals

The Oscillator of the SQM-160 is shown in figure 2-22 and the equivalent circuit for the Resonant

Oscillator is shown in figure 2-23

Fig 2-22 SQM-160 Oscillator

32

Fig 2-23 Oscillator Circuit

33

Table 2-2 Z-Ratios for Different Materials

Table 2-2 Continued

34

Table 2-2 Continued

35

Table 2-2 Continued

36

Table 2-2 Continued

37

Table 2-2 Continued

38

Table 2-2 Continued

235 Vacuum Chamber System

Vacuum Evaporation is the process of depositing thin films of materials onto surfaces The technique

consists of pumping a vacuum chamber to pressures of less than torr and heating a material to

produce a flux of vapor in order to deposit the material onto a surface The material to be vaporized is

typically heated until its vapor pressure is high enough to produce a flux several Angstrom per second by

using an electrically resistive heater or bombardment by a high voltage beam The process was invented

by Henri Nestle in 1886 for food industry

In here the system has been pumped to a vacuum of Torr When a high current is passed

through the filament boat the filament boat is heated over the desired metal evaporation temperature and

so evaporation starts When the evaporation process is finished and the metal cools down crystals

condensate in the surface of the wafer From the weight of the evaporated material the distance between

the filament boat and the wafer we are able to calculate the deposition thickness and we can also use the

mass detector follower like the Quartz crystal resonator microbalance system In the process of

evaporation we usually use a board in between the filament boat and the wafer This is because before we

arrive to the desired evaporation temperature there will be some impurities that will be vaporized in the

controlled environment so we first use a small current and the board in between to get rid of those

impurities and this raises the purity of the deposition material

39

A vacuum evaporation system is shown in figure 2-24

Fig 2-24 Vacuum Evaporation System

Rough Vacuum 760 ~ 1 torr

Medium Vacuum 1 ~ torr

High Vacuum ~ torr

Ultra-High Vacuum Lower than torr

Table 2-3 Classification of Vacuum

For our study we need to use a Turbo Pump A regular turbo pump is shown in figure 2-25

Fig 2-25 Turbo Pump

For our research we used the Pfeiffer TCP 015 Electronic Drive Unit and Granville Phillips 375

Convectron shown below in figure 2-26

40

Fig 2-26 Control and Measurement Equipment

The electronic drive controls the turbo pump and the Convectron measures the pressure inside our

chamber The turbo pump is a type of vacuum pump used to maintain high vacuum Most turbo pumps

are centrifugal When we start the pumping we need to use a mechanical pump so as to decrease the

pressure inside the system from constant atmospheric pressure to torr and then the use dispersion

pump to continue the vacuum until we get to the desired pressure We need to notice though when we

start the dispersion pump we canrsquot turn off the mechanical pump and they both need to run together If

we need to turn off the pumping we first turn off the dispersion pump wait for it to completely stop and

then turn off the mechanical pump

Our completely assembled system is shown in figure 2-27 below

Fig 2-27 Complete System

41

Chapter 3 TENSILE TESTING IN DEPTH

31 Experimentrsquos Purpose and Principles

By means of Universal testing machine and Strain gauges we were able to observe discuss and

analyze the phenomena created when a specimen of certain material is manipulated under an external load

and determine the stress strain and deformation values later we can use the graphing methods of

stress-strain diagram to describe it

The main point of this experiment is that after the tensile specimen is tested use computer analysis

and the actual strain data and after statistical adjustment make the final results report (Tensile testing

experiment is in accordance with ASTM E8)

32 Experimentrsquos Equipment

321 Universal Testing Machine

For the materials testing experiment part of this research we use a Universal Testing Machine as

shown in figure 31 The maximum load it can apply is 100 Ton After the test specimen is secured on the

device with the use of instrumentation the load exerted and the effects of this become apparent on the

specimen and even the smallest of changes can be recorded For our research we used the Chun Yen

Testing Machines Co Ltd 100 Ton Micro Computer Universal Tensile Tester

Fig 31 Universal Testing Machine

42

Table 31 shows the specifications for this machine

Max Capacity 100 Ton

Accuracy plusmn1

Tension (mm) Max Space 1150mm

Grip for Rod 20-70mm

Ram Stroke 250mm

Effective Column Interval 940mm

Crosshead Speed 300mmmin

Testing Speed 0-50mmmin

Volume of Machine 1700times1000times3350mm(LtimesWtimesH)

Volume of Control Panel 1000times800times1500mm(LtimesWtimesH)

Weight 8000kg

Power 3∮220V 20A

Computer AMD K6-2-350

OS Windows XP

Screen 15rdquo CRT

Table 3-1 Chun Yen Testing Machine Specs Table

The connections diagram is shown in figure 3-2

Fig 3-2 Diagram for System Connections

43

When the test specimen is placed when the external force is applied the Load Cell can measure the

size of the applied force and the Encoder measures the expansion rate of change The Local Controller

receives all the information from the 2 units after arranging the results they are displayed in the

computer and they can be afterwards submitted for more complex analysis such as Finite Element

Analysis and we can get the Stress-Strain Diagram

322 Strain Measurement Equipment

The equipment used in our research provides a four-channel measurement that means we can use up

to 4 strain gauges at a time to do our measurements and provides 3 different bridge arrangements as

shown in figure 3-3

(a) (b) (c)

Fig 3-3 Input Connections for Strain Indicator

Figure 3-3 (a) is the Quarter Bridge (b) is the Half Bridge and (c) is the Full Bridge and Transducers

For our study we used the Quarter Bridge and use the Strain Gauge values to decide the position of the

connecting wires The Strain indicator is shown in figure 3-4

Fig 3-4 Vishay Micro-Measurements Model P3 Strain Indicator and Recorder

44

Input Connections Tool Free eccentric lever release

4-channel input

Wire diameter16-28AWG

Bridge Configurations Quarter- Half- and Full Bridge

Bridge Impedance 60-2000Ω

Display 128 64 pixel FSTN positive gray LCD

Data Conversion AD Converter filter

Measurement Range Resolution Strain Range plusmn155mVV

Resolution plusmn00005mVV

Measurement Accuracy plusmn01 of reading plusmn3 counts

Gage Factor Control 0500-9900

Balance Control Software either manual or automatic

Bridge Excitation 15VDC nominal

Communication Interface USB Cable Included

Data Storage Removable Media Card

Shunt Calibration Across bridge completion resistors controlled

by software When Gage Factor=200

120Ω350Ω1000Ω

Analog Output Value 0 to 25V max

Ranges plusmn320 microε plusmn3200 microε plusmn32000 microε

Error 05 output voltage +5mV

Max Error 14 output voltage + 20mV

Update rate 480 samplessec

Output Load 2000Ω

Power Battery Two Alkaline D cells

Battery life 400 hours typ

USB 5V 100mA

Operational Environment Temperature 0-50

Humidity Up to 90 Non-condensing

Case Aluminum Alloy

Size and Weight 228times152times152(mm) 20(kg)

Table 3-2 Vishay Micro-Measurements Model P3 Strain Indicator and Recorder Specs

45

323 Strain Gauge

The strain gaugersquos main basic principle is to use a resistancersquos characteristics to measure the strain

The inside connections of the strain indicator are shown in figure 3-5

Fig 3-5 Inner Connections

As shown above this is a quarter-bridge connection We connect equal-length 3 wires to the 2

connections allowed by the strain gauge wire 1 and 3 can be used to cancel out the effects of temperature

to the resistance and because of the addition of wires 1 and 3 wire 2 can directly measure the experiment

results from the strain gauge and therefore the strain developed with no influence of temperature

If there were no two measuring leads then the relations will be

R 4 =R g +2R L

Where Rg is the Strain Gauge Value and RL is the wire resistance then

4

4

R

R=

Lg

g

RR

R

2

=

gL

gg

RR

RR

21

amp

4

4

R

R=

g

g

R

R(1- L)

Where L is the Signal Loss Factor and so

L =gL

gL

RR

RR

21

2

g

L

R

2R if

g

L

R

2Rltlt1

46

(Actual Value R g =120R L =08g

L

R

2Ris always much smaller than 1)

R 4 =R g +2R LR 2 =R 3 =rR gR 1 =R g 32 RR =0

V 0 =V 2)1( r

r

(

4

4

R

R-

1

1

R

R)

The first term describes loss attenuation effects second term describes loss of balancing capabilities

effects

V 0 =V 2)1( r

r

[

)2

(Lg

g

RR

R

+

T

Lg

g

RR

R

)

2( + T

Lg

L

RR

R

)

2

2( -(

g

g

R

R) T ]

The first term describes loss attenuation effects and loss of balancing capabilities effects the second

third and fourth terms describe the temperature effects on the wire

For the three-wire method we have

L =gL

gL

RR

RR

1

g

L

R

R if

g

L

R

Rltlt1

V 0 =V 2)1( r

r

[

)(Lg

g

RR

R

+

T

Lg

g

RR

R

)( + T

Lg

L

RR

R

)

2( -

T

Lg

g

RR

R

)( - T

Lg

L

RR

R

)

2( ]

V 0 = V2)1( r

r

)(

Lg

g

RR

R

In the last four terms inside parenthesis we can see the effects of temperature being cancelled out and the

effect on first term is not great so this is the reason why in our research we use three wires

47

324 Specimen Measurements

The tensile specimens used in this research are compliant of ASTM E8 Tensile parameters as shown

in figure 3-6

Fig 3-6 Tensile Specimen

Diameter

D(mm)

Gauge

Length

G(mm)

Smallest

Arc

Radius

R(mm)

Shortest

Area

A(mm)

Total

Length

L(mm)

Clamping

Area

Length

B(mm)

Clamping

Area

Diameter

C(mm)

Bar 125 02 625 01 gt10 gt75 ~ 145 ~ 35 20

Table 3-3 Specifications for Round Bar

33 Experiment Procedure

1 Attaching the Strain Gauge to the Tensile Specimen

(1) Prepare 1 ASTM E8 compliant tensile specimen round bar as shown in figure 3-7

(2) Prepare Strain Gauge as those described in table 3-4

(3) Prepare other consumables and adhesive agent such as epoxy adhesive or

cyanoacrylate adhesive as shown in figure 3-8

48

Fig 3-7 Actual Tensile Specimen

Fig 3-8 Other Materials Used (Such as Alcohol gauze transparent tape adhesive)

Gage Type

EA-06-120LZ-120E

Resistance in ohms at 24∘C

1200plusmn03

Gage Factor at 24∘C

2075plusmn05

Transverse Sensitivity at 24∘C

(+07plusmn02)

Table 3-4 Specifications for Strain Gauge

2 Attaching Strain Gauge

As shown in following figures we shall explain the attachment of the strain gauge

(1) Use sand paper and a rasp to clean thoroughly the surface where the strain gauge will be

attached to

49

(a)

(2) Use alcohol to wash the surface where the strain gauge will be attached and use gauze to rub

it off

(b)

(3) Find a clean surface and clean it with alcohol and gauze

(c)

(4) Place the strain gauge in the clean surface Use a piece of transparent tape on top of the strain

gauge after securely placed rip it off the surface carefully

50

(d)

(5) Use a piece of white paper to mark the place where the strain gauge will be attached and in

this way we can make sure that the strain gauge will be placed as horizontally and vertically

correct as possible

(e)

(6) In the place where we had our mark place the strain gauge

(f)

(7) Carefully lift one side of the tape and apply some of the adhesive agent to both the strain

gauge and specimenrsquos surface

(g)

51

(8) We need to make sure that the gauge and the specimen will be firmly attached so we gently

apply pressure with our thumb

(h)

(9) After the adhesive is fully dry we can carefully rip off the tape

(i)

(10) We need to do the whole process twice one for the horizontally placed strain gauge and one

for the vertically placed strain gauge

52

(j)

(11) We now proceed to solder the wires to the strain gauge

(k)

(12) After soldering we use a Volt Multimeter to measure that there is no contact between wires

If there is none then the specimen is ready for testing

(l)

(13) We now need to measure a 5cm distance and mark it to check and compare the elongation

before and after the tensile testing

(m)

53

Fig 3-9 Specimen-Strain Gauge Process

3 Tensile Test

(1) Enter the computer application that controls the tensile testing machine

(2) Turn on the tensile testing machine main switch

(3) Adjust the hydraulic pump to go back to its original position

(4) Bring the lowering motor down to a distance enough so as to attach the tensile specimen to the

system open the clamps and secure the specimen

(a)

(5) Connect all the necessary wires to the strain indicator equipment

54

(b)

(6) Start the ascending motor and wait for the expansion

(c)

Fig 3-10 Specimen-Tensile Testing Process

4 Start the Test

(1) Enter the software application and enter some variables needed for the experiment in the

specific screen

(2) Go back to the main screen and press the [測試] (measure) button to start the test and auto

recording in the software

(3) After the specimen breaks the mechanical device will automatically stop and ask the user to

enter the total displacement We take out the specimen from the testing machine and adjust the

machinersquos position back to its original position

(4) Save the results information

(5) Record the results from the strain indicator

34 Results

From this experiment we can get the Poissonrsquos Ratio Youngrsquos Modulus and Yield Strength etc and

because of the slippage phenomenon in the clamp at the moment of the test then the Elastic Limit will

display some yield phenomena So omit any undesirable results we just take the Yield portion of the

results as reference

In the process of the experiment the most important part to attend to is the attaching of the strain

gauge because the gaugersquos purpose is to measure the strain developed during the test and this strain

might be very small If the gaugersquos angle change during the test ie is not well attached this will affect

the accuracy of the measurements of Poissonrsquos ratio and Youngrsquos modulus

55

The materials provided by the manufacturer are SUM 23 and SUM 43 steel round bars and these two

types of materials have been through different heat treatment processes so they can be sub-divided

further into untreated material heat-treated material and black surface heat treated material for the two

materials with heat treatment the treatment process and finished are different In the end we only have

the mechanical properties that were calculated after our research of these materials

All of the specifications are identical to those shown in figure 3-6

341 SUM 23

Fig 3-11 SUM 23 Untreated Material

Number 7 10

Hardness(HRB) 74 75

Yield Stress (MPa) 448 440

Tensile Strength (MPa) 544 560

Poissonrsquos Ratio 029 027

Youngrsquos Modulus (GPa) 203 210

Cut-off Area Shrinking () 42 41

Elongation () 1125 1011

Table 3-5 Mechanical Properties of SUM 23 Untreated

56

Stress-Strain Diagram

(a)

(b)

57

Fig 3-12 Stress-Strain Diagrams for (a) 7 Round Bar and (b) 10 Round Bar

Cut-Off Area

(a)

(b)

Fig 3-13 Cut-Off Area of (a) 7 Round Bar and (b) 10 Round Bar

58

SUM 23 Nickel Round Bar

Fig 3-14 SUM 23 Nickel Material

Number 1 2 3 4

Hardness(HRB) 48 50 49 48

Yield Stress (MPa) 370 370 380 400

Tensile Strength (MPa) 455 451 450 450

Poissonrsquos Ratio 028 046 029 026

Youngrsquos Modulus (GPa) 243 303 246 206

Cut-off Area Shrinking () 803 803 726 601

Elongation () 566 65 602 647

Table 3-6 Mechanical Properties of SUM 23 Nickel

59

Stress-Strain Diagram

(a)

60

(b)

(c)

(d)

61

Fig 3-15 Stress-Strain Diagrams for (a) 1 Round Bar (b) 2 Round Bar (c) 3 Round Bar and (d)

4 Round Bar

Cut-Off Area

(a)

(b)

62

(c)

(d)

Fig 3-16 Cut-Off Area of (a) 1 Round Bar (b) 2 Round Bar (c) 3 Round Bar and (d) 4 Round

Bar

63

SUM 23 Black Surface Round Bar

Fig 3-17 SUM 23 Black Surface Material

Number 1 2 3

Hardness(HRB) 51 50 51

Yield Stress (MPa) 378 371 369

Tensile Strength (MPa) 467 465 464

Poissonrsquos Ratio 03 016 04

Youngrsquos Modulus (GPa) 215 266 266

Cut-off Area Shrinking () 986 94 848

Elongation () 748 805 761

Table 3-7 Mechanical Properties of SUM 23 Black Surface Material

64

Stress-Strain Diagram

(a)

(b)

65

(c)

Fig 3-18 Stress-Strain Diagrams for (a) 1 Round Bar 2 Round Bar and (c) 3 Round Bar

Cut-Off Surface

(a)

66

(b)

(c)

Fig 3-19 Cut-Off Surface of (a) 1 Round Bar 2 Round Bar and (c) 3 Round Bar

67

342 SUM 43

Fig 3-20 Untreated SUM 43 Untreated Material

Number 1 5

Hardness(HRB) 76 75

Yield Stress (MPa) 572 594

Tensile Strength (MPa) 743 785

Poissonrsquos Ratio 027 029

Youngrsquos Modulus (GPa) 200 202

Cut-off Area Shrinking () 338 2944

Elongation () 857 894

Table 3-8 Mechanical Properties of SUM 43 Untreated

68

Stress-Strain Diagrams

(a)

(b)

Fig 3-21 Stress-Strain Diagrams for SUM 43 (a) 1 Round Bar and (b) 5 Round Bar

69

Cut-Off Area

(a)

(b)

Fig 3-22 Cut-Off Area of SUM 43 (a) 1 Round Bar and (b) 5 Round Bar

70

SUM 43 Nickel Round Bar

Fig 3-23 SUM 43 Nickel Material

Number 4 5

Hardness(HRB) 51 50

Yield Stress (MPa) 1580 1544

Tensile Strength (MPa) 1639 1625

Poissonrsquos Ratio 03 028

Youngrsquos Modulus (GPa) 194 201

Cut-off Area Shrinking () 1697 137

Elongation () 376 265

Table 3-9 Mechanical Properties of SUM 43 Nickel

71

Stress-Strain Diagrams

(a)

(b)

Fig 3-24 Stress-Strain Diagrams for (a) 4 Round Bar and (b) 5 Round Bar

72

Cut-Off Area

(a)

(b)

Fig 3-25 Cut-Off Area of (a) 4 Round Bar and (b) 5 Round Bar

73

SUM 43 Black Surface Material

Fig 3-26 SUM 43 Black Surface Material

Number 3 5

Hardness(HRB) 56 56

Yield Stress (MPa) 1416 1361

Tensile Strength (MPa) 1591 1402

Poissonrsquos Ratio 029 031

Youngrsquos Modulus (GPa) 200 202

Cut-off Area Shrinking () 139 124

Elongation () 24 24

Table 3-10 Mechanical Properties of SUM 43 Black Surface Material

74

Stress-Strain Diagrams

0 2 4 6 8 10 12 14

-200

0

200

400

600

800

1000

1200

1400

1600

1800

應力 (MPa)

應變()

(a)

0 2 4 6 8 10

-200

0

200

400

600

800

1000

1200

1400

1600

應力

(MPa)

位移 ()

(b)

Fig 3-27 Stress-Strain Diagrams for (a) 3 Round Bar and (b) 5 Round Bar

(Note These curves were formulated using Visual Solutions Inc VisSim Software)

75

Cut-Off Area

(a)

(b)

Fig 3-28 Cut-Off Area of (a) 3 Round Bar and (b) 5 Round Bar

76

The force value (N) was retrieved from the Universal Testing Machine

The Poissonrsquos Ratio (ε) is calculated as

ε =

the values for the Poissonrsquos Ratio are in average around 0297

The Youngrsquos Modulus (E) is calculated as

E =

Where

Stress =

Cross-sectional Area =

where D is the Diameter

The value for D was in average around 1258 mm

The values shown by the computer because there is Slippage phenomena between the Clamp and the

specimen will not be taken into consideration for the elongation strain and Youngrsquos modulus and we will

refer to the values that we have meticulously calculated

77

Chapter 4 AR COATING IN DEPTH

41 Experimentrsquos Purpose and Principles

By means of a vacuum chamber and several other instruments we intend to apply Anti-Reflective

Coating using deposition process to a laser diode and in this way reduce its refraction so as to make it

lose less light in the process of amplification and we can control certain wavelengths we want produced

for certain desired applications in our case we are attempting to re-create a Bose-Einstein Condensate

An optimal BEC apparatus is shown in figure 4-1

Fig 4-1 BEC Apparatus

The main point of this experiment is to build a vacuum chamber system attach all the instrumentation

needed (Vacuum pump deposition meter and voltmeter) and use it to apply AR coating to a laser diode

After we have accomplished the AR coating other team will be in charge of designing the BEC apparatus

and use the results of our research

78

42 Experimentrsquos Equipment

421 Vacuum Chamber

For this research we designed a vacuum chamber whose main body is shown in figure 4-2 Its

dimensions are

Width 240 mm

Length 240 mm

Height 200 mm

Outer Diameter 4 in

Inner Diameter 15 in

Fig 4-2 Vacuum Chamber Main Body

The chamber is made up of 6 pass ways pass way A is the connection with the Laser Deposition

Equipment pass way B is the connection with the Turbo Pump and pass way C is for the connection with

the Deposition Source

A

C

B

79

Pass way C is for the deposition source as mentioned above This is a system where a thermal

resistance is heated by passing a high current through it which heats up a filament boat (made of tungsten)

where the material to be evaporated is place We control the temperature as such that the material will

evaporate and the heat will not cause the filament boat to crack

Because P = Isup2 R (where P is power I is current and R is resistance) to avoid the current to flow

where it is not desired we decided that the material for the Thermocouple shown in figure 4-3 should be

Copper ᴓ 63 mm We choose it that way because Copper has very good heat dissipation characteristics

and the resistance value is low It can reduce the value of the current enough to make the thermocouple to

create heat

Fig 4-3 Thermocouple

To the thermocouple we attach the tungsten filament boat We need to take notice of materials to be

used in this design because when using high current the tungsten filament boar will heat up and so the

material must be able to keep up with the heating potential of tungsten and has a low coefficient of heat

dissipation to avoid the tungsten to fail when heating up and therefore not evaporating Considering all

this we decide to use Stainless Steel

Because this clamp will be assembled inside the chamber after many revisions it was determined it

will have the shape shown in figure 4-4

Fig 4-4 Filament Boat Clamp Design

80

For the tungsten filament boat we bought the product from a distributor The dimensions are

Length 100 mm

Width 10 mm

Height 1 mm

Our thermocouple is 15 in but the pass way C is 4 in so we need to attach a Flange that connects

15in to 4in Because these specifications are quite difficult to achieve by Milling we had to use

electrical wire cutting

For the laser clamping system where the laser that is going to be AR coated will be placed will be

connected to pass way A the assembly is shown in figure 4-5 below

Fig 4-5 Cover Assembly

For this design we used an O-ring instead of a gasket so as to save time The design of the assembly

where the laser will be placed is shown in figure 4-6

Fig 4-6 Upper Cover Inner Assembly

D

E

F

81

Point D is the plate in the assembly where the laser diode will be fixed Because of the easy

processing we decide to use Aluminum and it is screwed to the top cover Point E is the connection for

the Quartz crystal resonator and it is designed in the same as point F in this way the results of the quartz

microbalance system will be more accurate in real time Point F is the final resting place for the laser

diode We use a Thor Labs Base with dimensions of ᴓ 9mm and ᴓ 56mm for two different size laser

diodes It just needs to be plugged in for easy installation

From figure 4-6 we know that the system needs signal system connections and because of the

change in temperature inside the chamber this could affect the functioning of the quartz microbalance so

we also need to install water tubes for cooling This is shown in figure 4-7 below

Fig 4-7 Diagram of Upper Cover Connections

In figure 4-8 we show the Feed through connections and their functions

Fig 4-8 Feed through Diagram

82

1 SQM-160 wire 5 Laser Connection 1 (Vin)

2 SQM-160 (G) 6 Laser Connection 2 (G)

3 K-Type-1 7 Laser Connection 3 (PD)

4 K-Type-2 8 Not In Use

The fully assembled chamber is shown in figure 4-9

Fig 4-9 Fully Assembled Chamber

422 Quartz Crystal Microbalance

For measuring the deposition on our target for coating we used the Inficon SQM-160 RateThickness

Monitor It is an easy to use instrument for measuring many types of thin-film coatings as shown in

figure 4-10

(a) Front Panel (b) Back Panel

Fig 4-10 Inficon SQM-160

83

Table 4-1 shows the technical specifications for this equipment

Number of sensors 2 Standard 4 additional optional

Sensor Frequency Range 40 MHz ~ 60 MHz

Reference Frequency Accuracy 002

Thickness Display Resolution 1 Aring

Thickness Resolution 015 Aring (Std) 0037 Aring (Hi Res)

Density of Stored Films 05-9999 gmcc

Tooling 10-399

Z-Factor 010-1000

Final Thickness 0000-9999k Aring

Measurement Period 15 to 2 sec

Simulation Mode Yes

Frequency Mode Yes

Rate Resolution 011 Arings

Dual Crystal Yes

Etch Mode Yes

Crystal Tooling 10-399

Crystal Fail Min Max 40 to 60 MHz 41 to 61 MHz

Power 100-120 200-240~plusmn10 nominal 20W

Operation Environment 0degC ~ 50degC

0 ~ 80 RH non-condensing

0 ~ 2000 meters

Class 1 Equipment

Pollution Degree 2

Rack Dimensions 885mm x 2127mm x 1969mm

Weight 27 kg

Table 4-1 Inficon SQM-160 RateThickness Monitor Specs

84

To the SQM-160 we need to connect an Oscillator We use the Sigma Instruments Remote Oscillator

Ser No 2 268 as shown in figure 4-11

Fig 4-11 Sigma Instruments Remote Oscillator

The connections diagram is shown in figure 4-12

Fig 4-12 SQM-160 Connections Diagram

85

423 Turbo Pump

For our experiments we used the Pfeiffer TCP 015 Electronic Drive Unit shown below in figure 4-13

Table 4-2 shows the technical specifications for this equipment

(a) Front Panel (b) Back Panel

Fig 4-13 Pfeiffer TCP 015 Electronic Drive

Connection Voltage (100V) 90-112

Mains Frequency 5060 Hz

Start-up Current 22 A

Nominal Frequency 1500 Hz

Rotation Speed 10V = 1500Hz plusmn2

Analog Output Current 10 V = 25 A plusmn 5

Rotation Speed Switchpoint 750 Hz

Works Setting 8 min

Permissible Ambient Temperature 0degC ~ 40degC

Dimensions Front Panel 1285mm x 1063mm

Insertion Length 227mm

Weight 27 Kg

Table 4-2 Pfeiffer TCP 015 Electronic Drive Specs

86

The connections diagram is shown in figure 4-14

Fig 4-14Connections Diagram for Pfeiffer TCP 015

To measure the pressure inside the chamber we use the Granville Phillips 375 Convectron Vacuum

Pressure Controller shown in figure 4-15

(a) Front Panel (b) Back Panel

Fig 4-15 Granville Phillips 375 Convectron

87

Its dimensions are shown in figure 4-16

Fig 4-16 Dimensions of Convectron

Table 4-3 shows the technical specifications for this equipment

Table 4-3 Granville Phillips 375 Convectron Vacuum Pressure Controller Specs

88

424 Multimeter

For our experiment we used the Keithley 2000 Digital Multimeter as shown in figure 4-17

(a) Front Panel (b) Back Panel

Fig 4-17 Keithley Model 2000 6-12-Digit Digital Multimeter

Its technical specifications are shown in table 4-4

Table 4-4 Keithley Model 2000 6-12-Digit Digital Multimeter Specs

89

43 Experiment Procedure

1 Connecting together the equipment and the chamber

(1) We first connect the resonator to the thickness monitor and connect the other side to the

chamber

(2) We now connect the flexible tubes to the turbo pump on one side and to the chamber on the

other

(3) We need to check that tubes are tightly connected to avoid any leaks in the vacuum pumping

process which will not allow us to get to our goal of Torr As shown in figure 4-18

(4) Connect the convectron to the system as shown in figure 4-19

Fig 4-18 checking for leaks using alcohol

Fig 4-19 Convectron attached to System

90

(5) Attach the clamps of the Multimeter to the bottom of the chamber as shown in figure 4-20

(6) Place the Quartz crystal in place

(7) Close tight vacuum chamber

(8) Connect all electrical appliances to power source

Fig 4-20 Multimeter Connections

2 Starting up the System

(1) We turn on all the devices as such Check all systems are ready to function Reset all values

that might be left over from previous tests

(2) Start the thickness monitor and set all values for this experiment In our case we got to testing

the system but not actual coating So we used the simulation mode of the thickness monitor as

shown in figure 4-21

Fig 4-21 Simulation Mode

91

(3) Start the turbo pump Make sure the lid on the vacuum chamber is tightly closed

(4) Start convectron and record initial pressure

(5) Start Multimeter and record initial current

3 Coating Process

(1) If we have the deposition material inside the filament boat the power source for the high

current must be started as well

(2) Record all initial values for thickness current pressure

(3) For an ideal experiment we need a thickness of around 101 nm a pressure of Torr and

a current of 300 A

44 Results

From previous experiments we have shown that we can turn a LED into a laser by means of AR

Coating In figure 4-22 shown below we can compare the actual results of a Diode before and after AR

coating From the blue line we can see that when the diode is at a current of 15mA its light will change

from LED to laser and if we look at the red line its critical current is around 30 to 35 mA

Fig 4-22 AR Coating Comparison for Laser Diodes

This means that the light emitted is not as strong as if the diode had been coated because inside the

chamber there must be some excitation first so the reflectivity of both sides inside the diode must be high

So because of the coating in one of the sides we have opened a door and let the light come out so the

critical current is risen as such and will be higher value than that of before the coating

92

In the following figures we can see the difference between before and after coating in a material The

thickness is around 1016 nm for this material

Fig 4-23 Before Coating

Fig 4-24 After Coating

93

Chapter 5 CONCLUSIONS AND RECOMMENDATIONS

51 Conclusions

For the first part of this independent study taking into consideration the data that came out of our

research and that sent by the provider we can say

1 SUM 23 after heat treatment will unexpectedly develop cracking in the middle of the tensile

testing process and suddenly break

2 Itrsquos possible that in the process of heat treatment to the SUM 23 material the treatment was not

uniform and this will create a pre-loaded moment force on one side that pushes on the other side

of the specimen resulting in material deformation

3 In the process of attaching the strain gauges to the materials it is very easy to make errors due to

poor adhesion or sudden removal in the tensile testing process

For our second part of the independent study the following can be made

1 At the beginning of this independent study we had no idea what Bose-Einstein Condensate was

or what was its purpose After much literature we finally comprehended the basic principles to

put into practice for our research

2 Our systemrsquos basic working principles and equipmentrsquos complexity are a little difficult to grasp

but hopefully we were able to understand enough of it

3 Theoretically from relation between the power and current we can know the advantages and

disadvantages of AR Coating

4 We were able to assemble the system and run test on its functions Even though we were able to

do this there is still much more work left to do with this system

52 Recommendations

For the Tensile Testing the following can be said

1 Ask the provider to check on the process of heat treatment on the SUM 23 material and give

them the information we have gathered through our test so they can correct for the mechanical

properties found if any change is needed

2 To avoid the problem of the inaccuracy of the poor adhesion of strain gauges we can attach

multiple strain gauges to the same one specimen so as to correlate data and improve our results

For the AR Coating the following can be said

1 We need to make sure that there are no physical defects on the main body of the chamber so as to

achieve maximum efficiency in the vacuum process If there was then the vacuum will arrive to

certain point and then start to decrease

2 It would be preferable to add some sort of visual aid that will allow the user to check the inside of

the chamber without actually opening it This will help us determine at what times we should

manipulate the current to better evaporate the substrate

94

REFERENCES

[1] A L Window Strain Gauge Technology Elsevier Applied Science London and New York 2nd

Edition 1992

[2] CC Perry and HR Lissner Strain Gauge Primer McGraw-Hill Book Co Inc New York 1955

[3] James W Dally William F Riley McGraw-Hill 1978

[4] University of Colorado Boulder BEC - What is it and where did the idea come from

httpwwwcoloradoeduphysics2000becwhat_is_ithtml

[5] Ultraslow Light amp Bose-Einstein Condensates Two-way Control with Coherent Light amp Atom

Fields Harvard Hau Lab Dr Lene Vestergaard Hau Optics amp Photonics News 16 1995

[6] The Art of Taming Light Ultra-slow and Stopped Light Harvard Hau Lab Dr Lene

Vestergaard Hau Europhysics News 2004

[7] Nonlinear Optics Shocking Superfluids Harvard Hau Lab Dr Lene Vestergaard Hau Nature

Physics 2007

[8] Model P3 Strain Indicator and Recorder Instruction Manual Vishay Micro-Measurements 2005

[9] Granville-Phillips Series 375 Convectron Vacuum Gauge Controller Instruction Manual Brooks

Automation 2008

[10] Effect of Film Thickness on the Validity of the Sauerbrey Equation for Hydrated Polyelectrolyte

Films Vogt Lin Wu White 2004

[11] Quartz Crystal Microbalance Study of DNA Immobilization and Hybridization for DNA Sensor

Development Chang Zhao 2008

[12] Installation of Strain Gages with SR-4 PrecoatAdhesive Vishay Micro-Measurements 2005

[13] Strain Gauge Measurement ndash A Tutorial National Instruments 1998

[14] Correlation between Vickers Hardness Number and Yield Stress of Cold-Formed Products

Yavuz Tekkaya

[15] httpsenwikipediaorg

Page 7: PC Hinge Materials Testing and AR Laser Diode Coating

7

LIST OF TABLES

Table 2-1 Rockwell Hardness Test Scalehelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 20

Table 2-2 Z-Ratios for Different Materialshelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 33

Table 2-3 Classifications of Vacuumhelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 39

Table 3-1 Chun Yen Testing Machine Specshelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 42

Table 3-2 Vishay Micro-Measurements Model P3 Strain Indicator and Recorder Specshelliphelliphelliphelliphelliphellip 44

Table 3-3 Specifications for Round Barhelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 47

Table 3-4 Specifications for Strain Gaugehelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 48

Table 3-5 Mechanical Properties of SUM 23 Untreatedhelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 55

Table 3-6 Mechanical Properties of SUM 23 Nickelhelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 58

Table 3-7 Mechanical Properties of SUM23 Black Surface Materialhelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 63

Table 3-8 Mechanical Properties of SUM 43 Untreatedhelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 67

Table 3-9 Mechanical Properties of SUM 43 Nickelhelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 70

Table 3-10 Mechanical Properties of SUM 43 Black Surface Materialhelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 73

Table 4-1 Inficon SQM-160 RateThickness Monitor Specshelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 83

Table 4-2 Pfeiffer TCP 015 Electronic Drive Specshelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 85

Table 4-3 Granville Phillips 375 Convectron Vacuum Pressure Controller Specshelliphelliphelliphelliphelliphelliphelliphelliphellip 87

Table 4-4 Keithley Model 2000 6-12-Digit Digital Multimeter Specshelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 88

8

LIST OF FIGURES

Fig 1-1 Notebook Computer Hingehelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 11

Fig 1-2 Basic Structure of Laserhelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 11

Fig 1-3 Comparison between LED and Laser Diodehelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 12

Fig 1-4 External Cavity Designhelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 12

Fig 2-1 Stress-Strain Curvehelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 14

Fig 2-2 Stress-Strain Curve Comparison on Metalshelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 15

Fig 2-3 Basic Structure of Strain Gaugehelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 17

Fig 2-4 Strain Gauge Attached to Wheatstone Bridgehelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 18

Fig 2-5 Brinell Indentationhelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 18

Fig 2-6 Brinell Hardness Testerhelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 18

Fig 2-7 Rockwell Indentationhelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 19

Fig 2-8 Rockwell Hardness Testerhelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 19

Fig 2-9 Vickers Indentationhelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 22

Fig 2-10 Vickers Hardness Testerhelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 22

Fig 2-11 Bose-Einstein Condensate at different scaleshelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 23

Fig 2-12 Super Conductorhelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 24

Fig 2-13 Simple Model for Light in Glass Mediumhelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 25

Fig 2-14 Simple Model for Light in Glass Medium after AR Coatinghelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 26

Fig 2-15 Light Passing through AR Coating and Glasshelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 27

Fig 2-16 Lens without and with AR Coatinghelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 27

Fig 2-17 Laser Diodehelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 28

Fig 2-18 Tunable Laser Basic Configurationhelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 28

Fig 2-19 Light Spectrumhelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 29

Fig 2-20 Front and Back Panel of SQM-160helliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 29

Fig 2-21 QCM Crystalshelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 31

Fig 2-22 SQM-160 Oscillatorhelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 31

Fig 2-23 Oscillator Circuithelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 32

Fig 2-24 Vacuum Evaporation Systemhelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 39

Fig 2-25 Turbo Pumphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 39

Fig 2-26 Control and Measurement Equipmenthelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 40

Fig 2-27 Complete Systemhelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 40

Fig 3-1 Universal Testing Machinehelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 41

Fig 3-2 Diagram for System Connectionshelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 42

Fig 3-3 Input Connections for Strain Gaugehelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 43

Fig 3-4 Vishay Micro-Measurements Model P3 Strain Indicator and Recorderhelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 43

Fig 3-5 Inner Connectionshelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 45

Fig 3-6 Tensile Specimenhelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 47

Fig 3-7 Actual Tensile Specimenhelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip47

Fig 3-8 Other Materials Usedhelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 48

Fig 3-9 Specimen-Strain Gauge Processhelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 49

Fig 3-10 Specimen-Tensile Testing Processhelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 53

9

Fig 3-11 SUM 23 Untreated Materialhelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 55

Fig 3-12 Stress-Strain Diagrams for 7 and 10 Round Barhelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 56

Fig 3-13 Cut-Off Area of 7 and 10 Round Barhelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 57

Fig 3-14 SUM 23 Nickel Materialhelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 58

Fig 3-15 Stress-Strain Diagrams for 1 2 3 and 4 Round Barhelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip60

Fig 3-16 Cut-Off Area of 1 2 3 and 4 Round Barhelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 62

Fig 3-17 SUM 23 Black Surface Materialhelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 63

Fig 3-18 Stress-Strain Diagrams for 1 2 and 3 Round Barhelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 65

Fig 3-19 Cut-Off Area of 1 2 and 3 Round Barhelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 66

Fig 3-20 SUM 43 Untreated Materialhelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip67

Fig 3-21 Stress-Strain Diagrams for 1 and 5 Round Barhelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 68

Fig 3-22 Cut-Off Area of 1 and 5 Round Barhelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 69

Fig 3-23 SUM 43 Nickel Materialhelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 70

Fig 3-24 Stress-Strain Diagrams for 4 and 5 Round Barhelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 71

Fig 3-25 Cut-Off Area of 4 and 5 Round Barhelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 72

Fig 3-26 SUM 43 Black Surface Materialhelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 73

Fig 3-27 Stress-Strain Diagrams for 3 and 5 Round Barhelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 74

Fig 3-28 Cut-Off Area of 3 and 5 Round Barhelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 75

Fig 4-1 BEC Apparatushelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 77

Fig 4-2 Vacuum Chamber Main Bodyhelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 78

Fig 4-3 Thermocouplehelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip79

Fig 4-4 Filament Boat Clamp Designhelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 79

Fig 4-5 Cover Assemblyhelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 80

Fig 4-6 Upper Cover Inner Assemblyhelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 80

Fig 4-7 Diagram of Upper Cover Connectionshelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 81

Fig 4-8 Feed Through Diagramhelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 81

Fig 4-9 Fully Assembled Chamberhelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 82

Fig 4-10 Inficon SQM-160helliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 82

Fig 4-11 Sigma Instruments Remote Oscillatorhelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 84

Fig 4-12 SQM-160 Connections Diagramhelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 84

Fig 4-13 Pfeiffer TCP 015 Electronic Drivehelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 85

Fig 4-14 Connections Diagram for Pfeiffer TCP 015helliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 86

Fig 4-15 Granville Phillips 375 Convectronhelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 86

Fig 4-16 Dimensions of Convectronhelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 87

Fig 4-17 Keithley Model 2000 6-12-Digit Digital Multimeterhelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 88

Fig 4-18 Checking for Leaks Using Alcoholhelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 89

Fig 4-19 Convectron Attached to Systemhelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 89

Fig 4-20 Multimeter Connectionshelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 90

Fig 4-21 Simulation Modehelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 90

Fig 4-22 AR Coating Comparison for Laser Diodeshelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 91

Fig 4-23 Before AR Coatinghelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 92

Fig 4-24 After AR Coatinghelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 92

10

Chapter 1 INTRODUCTION

11 Motivation and Background

In response that new generation computers are gradually reducing their size the diameter of

the structures of the hinges used by NB computers must also follow but the hinge strength may

also become smaller due to the reduction of diameter and result in the phenomenon of

insufficient strength In addition the disk-type spring that is source of the torque may also be

insufficient due to the narrowing of the structure Therefore it is necessary to direct a structural

analysis of the hinge for the existing laptops so that we can identify the stress concentration

point The stress concentration point is usually the point where material damage behavior is

encountered the easiest and if we can find the point where breaking occurs most often we can

improve the design of the existing structure to enhance the strength of the hinge structure

Second the structure of the hinge is too complicated the traditional mechanics of materials

analysis methods and formulas are no longer suitable for analysis of a wide arrange of hinge

design In recent years finite element analysis methods have been widely applied in various

fields such as electronics machinery aviation and so on

Therefore to meet the need of the industry and with the purpose of reducing design time

how to design a notebook computer hinge without compromising mechanical stability and

materialrsquos hardness which will operate equally under equal conditions In other words be able to

meet the needs of the size decreasing NB computers market as the needs for this kind of

accessories will increase in the near future If we take into consideration the traditional ways of

design we seek to reduce the costs of use of machinery and molding by applying Finite Element

Analysis methods to our study and also increase the flexibility of designing methods

The second project was brought in by Prof Chuang and it is to help in the further research of

the Bose-Einstein condensate This is a state of matter of a dilute gas weakly interacting bosons

(subatomic particles that obey the Bose-Einstein statistics) confined in an external potential and

cooled down to temperatures very near absolute zero (0 K or -27315deg C) Under these conditions

a large number of bosons occupy the lowest quantum state of the external potential at which

point quantum effects become apparent at macroscopic scale This state of matter was predicted

by Satyendra Nath Bose and Albert Einstein in 1924~1925 Then 70 years later the 1st gaseous

condensate was produced by Eric Cornell and Carl Wieman in 1995 at the University of

Colorado (Boulder) NIST-JILA lab and because of this along with Wolfgang Ketterle of MIT

they received the 2001 Nobel Prize in Physics

11

We wish to investigate the properties of Anti Reflecting Coating on laser diodes Hopefully

we will be able to achieve the desired effect of reducing the surface reflection coefficient and

find applications for it

12 Research Objective

We wish to analyze the normal composition of the notebook computerrsquos hinge at which

point in the assembly is clearly the weakest and at this time in the assembly the strength and

durability are influenced The main point is to see if we can affect the normal operation and work

life

The objective of this thesis is to present the results of the material properties under tensile

testing find the mechanical properties and after using finite element analysis determine what

material is the best for our purposes

Fig 1-1 Notebook Computer Hinge

For our second research we wish to produce and analyze laser diodes with anti-reflective

coating and test its properties and applications

When semi-conductor laser has been submitted to current it will produce resonance inside it

and light will be stimulated to come out Please refer to figure 1-2 for the basic structure of a

laser

Fig 1-2 Basic Structure of a Laser

1 Gain Medium

2 Laser Pumping Energy

3 High Reflector

4 Output Coupler

5 Laser Beam

12

But when the laser diode generates light but the laser diode canrsquot produce light on itself it

must wait for the current to be higher than certain value which is called the critical current Until

the light goes over this threshold then it is considered laser light if not it is just considered as a

common LED light source Please refer to figure 1-3

Fig 1-3 Comparison between LED and Laser Diode

As we can see from figure 1-3 all of the light that goes over the critical current is laser light

and so the external cavity semi-conductor laser that we built needs Anti-Reflective Coating

because the method we want to use needs an external cavity laser that has been covered with AR

Coating and a Diffraction Grating We use this configuration first by shooting the laser to the

grating and this will be shot back to the laser creating the external resonance cavity which is

shown in figure 1-4

Fig 1-4 External Cavity Design

13

Two configurations are shown the Littrow Configuration and the Littman-Metcalf

Configuration The Littrow configuration contains a collimating lens and a diffraction grating as

the end mirror The first order diffracted beam provides optical feedback to the laser diode which

has AR Coating The emission wavelength can be turned by rotating the diffraction grating A

disadvantage is that it also changes the direction of the output beam

In the Littman-Metcalf configuration the grating orientation is fixed and an additional mirror

is used to reflect the first order beam back to the laser diode The wavelength can be turned by

rotating that mirror This configuration offers a fixed direction of the output beam and also tends

to exhibit smaller line width as the wavelength selectivity is stronger A disadvantage is that

zero order reflection of the beam reflected by the tuning mirror is lost so that the output power is

less than that of a Littrow laser

13 Methodology

The aim of this research is to find the mechanical properties of materials after being

subjected to tensile testing through finite element analysis observations and determine what

material is best for our purposes taking into consideration the strength and durability of the

material among other properties to find use and applications for the AR coated laser diodes to

further improve the grasp of the Bose-Einstein condensation working principles

14 Organization of the Thesis

The research paper includes five chapters

1 Chapter 1 explains the motivation background objective and methodology of this study

2 Chapter 2 explains the working principles and basic knowledge needed to understand this

study

3 Chapter 3 explains the tensile testing in detail steps methods and results

4 Chapter 4 explains the AR coating in detail steps methods and results

5 Chapter 5 is the conclusions taken from the results shown in chapter 3 and 4 and

recommendations done after arranging and critical thinking

14

Chapter 2 BASICS THEORIES

21 Tensile Testing

After a specimen is tested with the use of tensile testing we can get the Stress-Strain Curve using the

relation between tension and displacement Typical curves are shown in Fig 2-1

(a) Ductile materials (b) Brittle materials

Fig 2-1 Stress-Strain Curve

The curve is unique for each material and is found by recording the amount of deformation at distinct

intervals of tensile or compressive loads Thanks to the use of the Stress-Strain curve we can get very

useful information such as

211 Youngrsquos Modulus (E)

As shown in Fig 2-1 as long as the external load is not greater than the Proportional Limit the Stress

(σ) and Strain (ε) remain as a linear relation fulfilling Hookersquos Law

σ = Eε

The slope is the constant factor the inverse of the modulus of elasticity E also called Youngrsquos

modulus When the external load goes over the proportional limit the stress-strain relationship doesnrsquot

follow the linear relation anymore but the deformation remains flexible When the load is released the

deformation is completely eliminated and the specimen goes back to its original state This is called

15

Elastic Deformation When the external load goes over the Elastic limit only then does the specimen

presents Plastic Deformation This type of deformation which is irreversible even when the load is

removed comes after the material does under elastic deformation so this means the object will first come

part way to its original shape Common metals and ceramics have roughly the same elastic limits

212 Yield Strength and Yield Point

Some materials display very evident yield phenomena while some materials donrsquot as shown in Fig

2-2 After we exceed the elastic limit if we continue to exert load when we arrive to a certain value

which differs under different materials and external conditions there is sudden decrease in stress and this

is called the Yield Strength and can be defined as the stress at which a material begins to deform

plastically using the equation

σyield =

Where P is the tension force and Ao is the original cut-off area

The stress remain at a certain value after the decrease but the strain increases this phenomena can be

easily appreciated when studying the behavior of common Carbon Steel Fig2-2 (a) but most metals (like

Aluminum Copper or High Steel Carbon) donrsquot display this kind of behavior as shown in Fig 2-2 (b)

Arriving to this point is very difficult and the most commonly used method for this is to add a 02 or

0002 offset yield strength to the curve This point is held constant on the strain axis of the curve and

from the 0002 position we draw a straight line parallel to the linear relationship line the point at where

this line and the stress-strain curve intercept is the point we take as the 02 offset yield strength

(a)Evident (b) Non-evident

Fig2-2 Stress-Strain Curve Comparison on Metals

16

213 Ultimate Tensile Strength and Breaking Strength

After materials undergo yield they keep lending strength and hardening phenomena occurs (work

hardening) on the material and the external load increases When it has reached the highest point this is

called the Ultimate Tensile Strength (UTS) as shown in Fig2-1 The UTS is defined as

σUTS =

Where Pmax is the load at the materialrsquos ultimate tensile strength point and Ao is the original cut-off

area For brittle materials the ultimate tensile strength is the most important mechanical property for

ductile materials the ultimate tensile strength is not commonly used for industrial and designing purposes

because upon arriving to this value the material already has forgone great plastic deformation After the

specimen goes through UTS there will be necking phenomena which is a mode of tensile deformation

where relatively large amounts of strain localize disproportionately in a small region of the material It

results from instability during tensile deformation when a materialrsquos cross-sectional area decreases by a

greater proportion than the material strain hardens The specimen continues to elongate until it finally

breaks and the load at this point is called Breaking Strength The breaking strength is defined as the

greatest stress in tension that a material is capable of withstanding without rupture

Where Pf is the load at the materialrsquos breaking strength point and Ao is the original cut-off area

214 Poissonrsquos Ratio (ν)

For elastic deformation when materials are compressed in one direction they tend to expand in the

other two directions perpendicular to the direction of compression This is called the Poissonrsquos Effect

The Poison Ratio is a measure of the Poissonrsquos effect It is the ratio of the fraction of expansion divided

by the fraction of compression for small values of these changes

ν=-

215 Strain Gauge Basic Principles

The strain gauge is a device used to measure the strain of an object Itrsquos an elongated metal resistor

which is attached to the specimen being measured and when the specimen is under strain and starts to

deform the strain gauge will have a change in the resistance With the change in value we can calculate

the elementrsquos strain or elastic modulus and the Poissonrsquos ratio

It takes advantage of the physical property of electrical conductance and its dependence on the

conductorrsquos geometry When the electrical conductor (the specimen being tested) is stretched within the

limits of elasticity such that it does not break or deform plastically it will become narrower and longer

17

which increases the electrical resistance through-out From the measured resistance of the strain gauge

the amount of stress may be inferred by using the relations

R=

Where R is the original resistance value is the electrical resistivity lo is the original length of the

conductor and Ao is the original cross sectional area of the conductor If after the application of tension

the change in length is Δl let the length of the specimen be l = l + Δlo and the tension is the same

through-out So

And the resistance is

The Gauge Factor is the ratio of relative change in electrical resistance to the mechanical strain in

other words it is the relative change in length It is defined as

The strain gauge was invented in 1938 by Edward E Simmons and Arthur C Ruge and the most

common type consists of an insulating flexible backing which supports a metallic foil usually made of a

brass-nickel alloy It is attached to the specimen by a suitable adhesive As the object is deformed the foil

also deforms and this causes the electrical resistance to change Then this is usually measured using a

Wheatstone bridge shown below and is related to the strain by the Gauge Factor

Fig2-3 Basic Structure of Strain Gauge

18

Fig 2-4 Strain gauge attached to Wheatstone bridge

22 Hardness Testing Basic Principles

221 Brinell Scale BHN

The Brinell Scale characterizes the indentation hardness of materials through the scale of penetration

of an indenter loaded on a material specimen The typical test uses a 10mm diameter steel ball as indenter

(usually of value equal to BHN450) with a 29kN force For softer materials smaller force is used The

indentation is measured and BHN is calculated using the relation

BHN =

radic

Where F is the applied force usually within the range of 100 250 500 750 1000 1500 2000 2500

and 3000 kgf D is the diameter of indenter usually within the range of 5mm or 10mm plusmn0005 margin

and d is the diameter of indentation usually around 2mm Its units are of Kgmmsup2 but are not normally

written

First proposed by Swedish engineer Johan August Brinell in 1900 it was the first widely used and

standardized hardness test in engineering and metallurgy although the large size of indentation and

possible damage to specimen limits its usefulness

Fig 2-5 Brinell Indentation Fig2-6 Brinell Hardness Tester

19

222 Rockwell Scale HR

The Rockwell scale is a hardness scale based on the indentation hardness of a material The Rockwell

test determines the hardness by measuring the depth of penetration of an indenter under a large load

compared to the penetration made by a preload The indenter is forced into the specimen under a

preliminary load When equilibrium is reached a measuring device follows the movements of the

indenter and responds to changes in depth of penetration of the indenter While the preload is still being

applied additional major load is applied resulting in increased penetration When equilibrium is reached

again the major load is removed but the preload is maintained Removing the major load allows partial

recovery and reduces the depth of penetration The permanent increase in depth of penetration resulting

from the application and removal of the major load is used to calculate the Rockwell number using the

relation

HR = E ndash e

Where E is a constant depending on the form of the indenter 100 units for diamond indenter and 130

units for steel ball indenter e is the permanent increase in depth of penetration due to the major load

measured in units of 0002mm

Fig 2-7 Rockwell Indentation

When testing materials indentation hardness is related linearly to the tensile strength The important

relation permits economically important nondestructive testing of bulk metal deliveries with lightweight

equipment like the Rockwell tester shown below in figure 2-7

Fig 2-8 Rockwell Hardness Tester

20

There are different scales denoted by a single letter that use different loads or different indenters

The result is a dimensionless number denoted as HR X where X will be the letter denoting the scale as

shown below in table 2-1

Table 2-1 Rockwell Hardness Test Scale

Differential depth hardness measurement was first conceived in 1908 by Viennese professor Paul

Ludwik It eliminated the errors associated with the mechanical imperfections of the system such as

backlash and surface imperfections in the specimen Rockwell testing has an advantage over Brinell

testing because the latter was slow itrsquos not useful on fully hardened steel and left too large an impression

to be considered nondestructive

The tester was co-invented by Hugh M Rockwell and Stanley P Rockwell The requirement for this

tester was to quickly determine the effects of heat treatment on steel bearing races

21

223 Vickers Hardness Test HV

This is a type of microindentation hardness test where a diamond indenter of specific geometry is

impressed into the surface of the test specimen using a known applied force ranging from 10 to 1000

grams This type of tests usually has forces of 2N and produce indentations of about 50μm They can be

used to observe changes in hardness on the microscopic scale It is difficult to standardize the

microhardness measurements because it has been found that the microhardness of almost any material is

higher than its macrohardness The values also vary with load and work-hardening effects of materials

The Vickers test is often easier to use than other hardness tests because the required calculations are

independent of the size of the indenter and the indenter can be used for all materials It can be used for all

metals and has one of the widest scales among hardness tests The unit of the Vickers test is denoted as

HV and can be converted to units of Pascal (Pa) but it is not a measurement of pressure The hardness

number is determined by the load over the surface area of the indentation and not the area normal to the

force

A square-based pyramid shaped diamond is use as the indenter It has been established that the ideal

size of a Brinell impression was 38 of the ball diameter As two tangents to the circle at the ends of a

chord 3d8 long intersect at 136plusmn05deg it was decided to use this as the angle of the indenter giving an

angle to the horizontal plane of 22deg on each side The HV number is determined by the ratio FA where F

is the force applied to the diamond in kgf and A is the surface area of the resulting indentation in mmsup2 A

can be determined by the relation

A =

Where A is the surface area of indentation and d is the average length diagonal left by the indenter

This can be approximated as

A =

Then the Vickers Number is

HV =

=

Vickers hardness number is reported as xxxHVyy or xxxHVyyzz (if duration of applied force differs

from 10s to 15s) where xxx are replaced by the hardness number yy is the load in kg and zz indicates

loading time The values are generally independent of test force

The test was developed in 1921 by Robert L Smith and George E Sandland at Vickers Ltd as an

alternative to Brinell method to measure the hardness of materials

22

Fig 2-9 Vickers Indentation Fig 2-10 Vickers Hardness Tester

23 AR Coating

231 Bose-Einstein Condensate

The Bose-Einstein Condensate or BEC is a state of matter of a dilute gas of bosons cooled to

temperatures very near absolute zero around 0K or -27315degC Under such conditions a large fraction of

the bosons occupy the lowest quantum state where the quantum effects become apparent on a

macroscopic scale This gave birth to the Bose-Einstein Statistics which are the rules that govern the

behavior at this state It is one of the two possible ways in which a collection of indistinguishable particles

may occupy a set of available discrete energy states The aggregation of particles in the same state

accounts for the cohesive streaming of laser light and the frictionless creeping of superfluid helium (an

application discussed later) Bose and Einstein recognized that a collection of identical and

indistinguishable particles can be distributed this way This theory applies only to those particles not

limited to single occupancy of the same state particles that do not obey the Pauli Exclusion Principle

restrictions Such particles are the Bosons named after the statistics that correctly describe their behavior

This phenomenon was first predicted by Satyendra Nath Bose around 1924 when he considered how

groups of photons behave He then asked Albert Einstein for help publishing his discoveries to which

Einstein agreed and gave follow up supporting these findings The resulting efforts became the concept of

a Bose gas governed by the Bose-Einstein Statistics described above Einstein demonstrated that cooling

bosonic atoms to a very low temperature would cause them to condense into the lowest accessible

quantum state resulting in a new form of matter

The first gaseous condensate we produced by Eric Cornell and Carl Wieman at the University of

Colorado at Boulder NIST ndash JILA lab sung a gas of rubidium atoms cooled to 170 nK which earned

them the 2001 Nobel Prize in physics together with Wolfgang Ketterle from MIT The transition to BEC

occurs below a critical temperature which for a uniform three dimensional gas consisting of

non-interacting particles with no apparent internal degrees of freedom is given by

23

Tc =

(

)

asymp 33125

Where Tc is the critical temperature n is the particle density m is the mass per boson h is the

reduced Planck constant k is the Boltzmann constant and ζ is the Riemann zeta function

There are two classes of elementary particles defined by whether their quantum spin is a nonnegative

integer or an odd half integer A Bose-Einstein Condensate is shown below in figure 2-11

Fig 2-11 Bose Einstein Condensate at different scales

Bosons are the particles whose quantum spin is a nonnegative integer (s = 0 1 2 etc) Examples of

bosons include fundamental particles (Higgs Boson Photons W and Z Bosons Gluons Gravitons etc)

composite particles (Mesons Hadrons Nuclei and Atoms of Carbon-12 and Helium-4) and

quasi-particles Bosons are considered force carrier particles The Bosons differ from Fermions in that

there is no limit to the number that can occupy the same quantum state This is called the Pauli Exclusion

Principle

The Pauli Exclusion Principle says that no two identical fermions may occupy the same quantum state

simultaneously in other words this means that the total wave function for two identical fermions is

anti-symmetric with respect to exchange of the particles This means that no two electrons in a single

atom can have the same four quantum numbers

Fermion is any particle characterized by Fermi-Dirac Statistics and follows the Pauli Exclusion

Principle described above Quarks Leptons and composite particles (Hadrons Nuclei and Atoms of

Carbon-13 and Helium-3) made of an odd number of these are considered Fermions It can be an

elementary particle such as the electron or a composite particle such as the protons Following the Pauli

24

Exclusion Principle only one fermion can occupy a particular quantum state at any given time If multiple

fermions have the same spatial probability distribution then at least one property of each fermion must be

different Fermions are usually associated with matter because composite fermions are key building

blocks of matter (neutrons and protons)

Fermionsrsquo behavior by the Fermi-Dirac Statistics which describes the energies of single particles in a

system comprising of many identical particles It applies to identical particles with half-odd integer spin

in a system of thermal equilibrium The particles in the system are assumed to have negligible mutual

interaction This allows the many-particle system to be described in terms of single-particle energy states

The result is the Fermi-Dirac distribution of particles over these states and includes the condition that no

two particles can occupy the same state which has considerable effect on the properties of the system

In quantum mechanics the position of an object is uncertain An object has a definite probability of

being at any given point in space This probability is encoded in the wave function mentioned earlier If

one concentrates a large number of identical bosons in a small region then it is possible for their wave

functions to overlap so much that the bosons lose their identity When this happens thatrsquos a Bose-Einstein

Condensate It is only possible at very low temperatures because at high temperatures the individual

bosons have small wave functions and move rapidly which causes them to fly apart

For now applications are still restricted because there are still some setbacks regarding BECs They

are extremely fragile they are being produced in small quantities with just a few million atoms at a time

and finally they can only be made from certain types of atoms Some examples are the atom laser Ketterle

in which a conventional light lase emits a beam of coherent photons this means they are all in phase and

can be concentrated to an extremely small bright spot BECs can slow down light as demonstrated by

Prof Lene Hau PhD in 2001 by the use of a superfluid [7] These manipulations could develop into

new types of telecommunications technology optical storage and quantum computing

BECs are related to super-fluidity and super-conductivity Super-fluidity is the state of matter in

which the behavior is that of a fluid with zero viscosity It was discovered in liquid helium but now it has

applications in astrophysics high-energy physics and theories of quantum gravity

Super-conductivity is a phenomenon of exactly zero electrical resistance and expulsion of magnetic

fields occurring in certain materials when cooled below a characteristic critical temperature A

super-conductor is shown below in figure 2-12

Fig2-12 Super Conductor

25

232 AR Coating Basic Principles

Anti-reflective (AR) coating is a type of optical coating applied to the surface of lenses and other

optical devices (in our case we planned to apply it to a laser diode) to reduce reflection This improves

the efficiency of the system since less light is lost The primary benefit is the elimination of the reflection

itself

When light the medium (glass) it will produce reflection if 100 of the light comes from the air and

enters the glass because therersquos a difference between the index of refraction some of the light will go out

and when the light is coming out of the glass into the air once again because of the difference between

index of refraction some of the light wonrsquot be able to pass through the medium

When the light makes the first trip into the glass there was a loss of about 4 in the reflection and

when the light makes the trip back outside there was another loss of about 4 so when we assume that

100 of the light interacts with the medium actually therersquos just about 92 acting (we neglect the light

absorbed by the glass around 05) To illustrate this idea please refer to figure 2-13

Fig 2-13 Simple Model for Light in Glass Medium

When we apply the AR Coating the light that enters will only have a loss of about 05 and when

making the trip back outside again only 05 of light is loss so we get the result of increasing the light

passing through up to 99 (again neglecting the light absorbed by the glass around 05) To illustrate

this idea please refer to figure 2-14

26

Fig 2-14 Simple Model for Light in Glass Medium after AR Coating

The AR Coating can reduce reflection of incoming light In the case that light hits perpendicular to

the surface of the medium the intensity of the reflection can be calculated using the Reflection

Coefficient

Where n0 and ns are the refractive indices of the first and second media respectively The value of R

varies from 0 (no reflection) to 1 (all light reflected) and is usually quoted as a percentage

Complementary to R is the transmission coefficient or Transmittance If absorption and scattering are

neglected then the value of Transmittance is always 1-R then if a beam of light with intensity I is

incident on the surface a beam of intensity RI is reflected and a beam with intensity TI is transmitted to

the medium

The optimal value is called the Optimal Index of Refraction and is described as

For glass with ns around 15 in air (n0 around 10) then the optimum refractive index will be n1 =

1225

To reduce the refraction in this case we now mean the one that is produced inside the chamber of the

Laser diode the easiest way is to apply a low reflectivity AR coating on the surface of the laser To

measure the appropriate thickness of the coating layer we can use the equations described above By

applying a coat exactly

thickness film we can assure that a certain wavelength is transmitted The

27

reflected waves from the back of the glass medium will be half a wavelength out of phase So they

interfere destructively Because all reflected waves are interfered the maximum amount of light passes

through the coating Please refer to figure 2-15 to illustrate this idea

Fig 2-15 Light Passing through AR Coat and Glass

The most common process to attain this final product is by vacuum deposition For the best coating

results we need to lower the pressure inside the vacuum system to torr

Fig 2-16 Lens without (Top) and With (Bottom) AR Coating

28

233 Laser Diode Basic Principles

A laser diode is a laser whose active medium is a semiconductor similar to that found in

light-emitting diodes (LEDs) Please refer to figure 2-17 The most common type of laser diode is formed

from a p-n junction and powered by injected electric current

Fig 2-17 Laser Diode

Laser diodes are formed by doping a very thin layer on the surface of a crystal wafer The crystal is

doped to produce the n-type region and a p-type region one above the other

By referring to figure 1-2 we can see the basic structure of a working laser When the laser diode has

a current passing through it the light will get excited inside its gain medium and then will start to

resonate this process is called pumping The current exceeds the critical current and then it comes out as

laser light Please refer to figure 1-3 Since we use an external cavity laser we need to apply the AR

coating to the diode and adjust a diffraction grating The laser light comes out the diode and bounces on

the grating making the resonance externally and this becomes the ldquocavityrdquo as shown in figure 2-18

Fig 2-18 Tunable Laser Basic Configuration

29

The most important feature of the external cavity laser is that we can adjust the wavelength easily just

by changing the diffraction gratingrsquos angle and in the end this is the output wavelength of the laser For

different wavelengths there will be different levels of visible light as shown in figure 2-19

Fig 2-19 Light Spectrum

234 Quartz Microbalance System

A Quartz Crystal Microbalance is an instrument that measures a mass per unit area by measuring the

change in frequency of a quartz crystal resonator The resonance is disturbed by the addition or removal

of a small mass due to oxide growthdecay or film deposition (which is the case in our study) at the

surface of the acoustic resonator The QCM can be used under vacuum in gas phase and more recently in

liquid environments It is useful for monitoring the rate of deposition in thin film deposition systems

under vacuum Frequency measurements are easily made with high precision

For our research we used the Sigma Instruments SQM-160 RateThickness Monitor shown in figure

2-20

Fig 2-20 Front and Back Panels of SQM-160

30

The microbalance uses Quartz as the resonator Quartz is one member of the family of crystals that

experience the Piezoelectric Effect

Piezoelectricity is the charge that accumulates in certain solid materials in response to applied

mechanical stress It means electricity resulting from pressure It was discovered in 1880 by Jacques and

Pierre Curie It is understood as the linear electromechanical interaction between the mechanical and the

electrical state in crystalline materials with no inversion symmetry It is a reversible process in that

materials exhibiting direct piezoelectricity also exhibit the reverse This means that the internal generation

of electrical resulting from applied mechanical force and vice versa

By using the piezoelectric effect we can probe as an acoustic resonance by electrical means Applying

alternating current to the quartz crystal induces oscillations This creates a shear wave We can use these

qualities to determine the resonance frequency at high accuracy

The frequency of oscillation of the crystal is partially dependent in the thickness of the crystal During

normal operation all the variables are held constant so a change in thickness correlates directly to a

change in frequency As mass is deposited or etched away the thickness increases or decreases and so the

frequency of oscillation changes accordingly With some simplifying assumptions the frequency change

can be quantified and correlated precisely to the mass change using the Sauerbreyrsquos Equation

Developed by G Sauerbrey in 1959 it is a method for correlating changes in the oscillation

frequency of a piezoelectric crystal with the mass deposited on it It is defined as below

Where f0 is the Resonant frequency Δf is the Frequency change Δm is the mass change A is the

piezoelectrically active area of the crystal q is the Density of quartz (2648 gcmsup3) and μq is the Shear

modulus of quarts(2947x gcmssup2)

Because the film is treated as an extension of thickness Sauerbreyrsquos equation only applies to systems

in which the following 3 conditions are met

Deposited mass must be rigid

Deposited mass must be distributed evenly

The frequency change

lt002

If the change is greater than 2 the Z-match method must be used to determine the change in mass

It is defined as

Where fL is the frequency of the loaded crystal fU is the resonant frequency Nq is the frequency

constant (1668x HzAring) Δm is the mass change A is the piezoelectrically active area of the crystal

31

q is the density of quartz Z is the method constant f is the density of film μq Is the shear modulus of

quarts and μf is the shear modulus of film

The Sauerbrey equation cannot be applied to systems under liquid medium

The crystals are seed crystals plated with gold on both top and bottom for applications A crystal is

shown in figure 2-21 The QCM consists of a thin piezoelectric plate with electrodes evaporated on both

sides Due to the piezoelectric effect AC voltage across the electrodes induces a shear deformation and

vice versa The electromechanical coupling provides a simple way to detect an acoustic resonance by

electrical means

The Z also called Z-factor is a constant value for different materials and it is shown together with the

density of different materials in table 2-2 below

Fig 2-21 QCM Crystals

The Oscillator of the SQM-160 is shown in figure 2-22 and the equivalent circuit for the Resonant

Oscillator is shown in figure 2-23

Fig 2-22 SQM-160 Oscillator

32

Fig 2-23 Oscillator Circuit

33

Table 2-2 Z-Ratios for Different Materials

Table 2-2 Continued

34

Table 2-2 Continued

35

Table 2-2 Continued

36

Table 2-2 Continued

37

Table 2-2 Continued

38

Table 2-2 Continued

235 Vacuum Chamber System

Vacuum Evaporation is the process of depositing thin films of materials onto surfaces The technique

consists of pumping a vacuum chamber to pressures of less than torr and heating a material to

produce a flux of vapor in order to deposit the material onto a surface The material to be vaporized is

typically heated until its vapor pressure is high enough to produce a flux several Angstrom per second by

using an electrically resistive heater or bombardment by a high voltage beam The process was invented

by Henri Nestle in 1886 for food industry

In here the system has been pumped to a vacuum of Torr When a high current is passed

through the filament boat the filament boat is heated over the desired metal evaporation temperature and

so evaporation starts When the evaporation process is finished and the metal cools down crystals

condensate in the surface of the wafer From the weight of the evaporated material the distance between

the filament boat and the wafer we are able to calculate the deposition thickness and we can also use the

mass detector follower like the Quartz crystal resonator microbalance system In the process of

evaporation we usually use a board in between the filament boat and the wafer This is because before we

arrive to the desired evaporation temperature there will be some impurities that will be vaporized in the

controlled environment so we first use a small current and the board in between to get rid of those

impurities and this raises the purity of the deposition material

39

A vacuum evaporation system is shown in figure 2-24

Fig 2-24 Vacuum Evaporation System

Rough Vacuum 760 ~ 1 torr

Medium Vacuum 1 ~ torr

High Vacuum ~ torr

Ultra-High Vacuum Lower than torr

Table 2-3 Classification of Vacuum

For our study we need to use a Turbo Pump A regular turbo pump is shown in figure 2-25

Fig 2-25 Turbo Pump

For our research we used the Pfeiffer TCP 015 Electronic Drive Unit and Granville Phillips 375

Convectron shown below in figure 2-26

40

Fig 2-26 Control and Measurement Equipment

The electronic drive controls the turbo pump and the Convectron measures the pressure inside our

chamber The turbo pump is a type of vacuum pump used to maintain high vacuum Most turbo pumps

are centrifugal When we start the pumping we need to use a mechanical pump so as to decrease the

pressure inside the system from constant atmospheric pressure to torr and then the use dispersion

pump to continue the vacuum until we get to the desired pressure We need to notice though when we

start the dispersion pump we canrsquot turn off the mechanical pump and they both need to run together If

we need to turn off the pumping we first turn off the dispersion pump wait for it to completely stop and

then turn off the mechanical pump

Our completely assembled system is shown in figure 2-27 below

Fig 2-27 Complete System

41

Chapter 3 TENSILE TESTING IN DEPTH

31 Experimentrsquos Purpose and Principles

By means of Universal testing machine and Strain gauges we were able to observe discuss and

analyze the phenomena created when a specimen of certain material is manipulated under an external load

and determine the stress strain and deformation values later we can use the graphing methods of

stress-strain diagram to describe it

The main point of this experiment is that after the tensile specimen is tested use computer analysis

and the actual strain data and after statistical adjustment make the final results report (Tensile testing

experiment is in accordance with ASTM E8)

32 Experimentrsquos Equipment

321 Universal Testing Machine

For the materials testing experiment part of this research we use a Universal Testing Machine as

shown in figure 31 The maximum load it can apply is 100 Ton After the test specimen is secured on the

device with the use of instrumentation the load exerted and the effects of this become apparent on the

specimen and even the smallest of changes can be recorded For our research we used the Chun Yen

Testing Machines Co Ltd 100 Ton Micro Computer Universal Tensile Tester

Fig 31 Universal Testing Machine

42

Table 31 shows the specifications for this machine

Max Capacity 100 Ton

Accuracy plusmn1

Tension (mm) Max Space 1150mm

Grip for Rod 20-70mm

Ram Stroke 250mm

Effective Column Interval 940mm

Crosshead Speed 300mmmin

Testing Speed 0-50mmmin

Volume of Machine 1700times1000times3350mm(LtimesWtimesH)

Volume of Control Panel 1000times800times1500mm(LtimesWtimesH)

Weight 8000kg

Power 3∮220V 20A

Computer AMD K6-2-350

OS Windows XP

Screen 15rdquo CRT

Table 3-1 Chun Yen Testing Machine Specs Table

The connections diagram is shown in figure 3-2

Fig 3-2 Diagram for System Connections

43

When the test specimen is placed when the external force is applied the Load Cell can measure the

size of the applied force and the Encoder measures the expansion rate of change The Local Controller

receives all the information from the 2 units after arranging the results they are displayed in the

computer and they can be afterwards submitted for more complex analysis such as Finite Element

Analysis and we can get the Stress-Strain Diagram

322 Strain Measurement Equipment

The equipment used in our research provides a four-channel measurement that means we can use up

to 4 strain gauges at a time to do our measurements and provides 3 different bridge arrangements as

shown in figure 3-3

(a) (b) (c)

Fig 3-3 Input Connections for Strain Indicator

Figure 3-3 (a) is the Quarter Bridge (b) is the Half Bridge and (c) is the Full Bridge and Transducers

For our study we used the Quarter Bridge and use the Strain Gauge values to decide the position of the

connecting wires The Strain indicator is shown in figure 3-4

Fig 3-4 Vishay Micro-Measurements Model P3 Strain Indicator and Recorder

44

Input Connections Tool Free eccentric lever release

4-channel input

Wire diameter16-28AWG

Bridge Configurations Quarter- Half- and Full Bridge

Bridge Impedance 60-2000Ω

Display 128 64 pixel FSTN positive gray LCD

Data Conversion AD Converter filter

Measurement Range Resolution Strain Range plusmn155mVV

Resolution plusmn00005mVV

Measurement Accuracy plusmn01 of reading plusmn3 counts

Gage Factor Control 0500-9900

Balance Control Software either manual or automatic

Bridge Excitation 15VDC nominal

Communication Interface USB Cable Included

Data Storage Removable Media Card

Shunt Calibration Across bridge completion resistors controlled

by software When Gage Factor=200

120Ω350Ω1000Ω

Analog Output Value 0 to 25V max

Ranges plusmn320 microε plusmn3200 microε plusmn32000 microε

Error 05 output voltage +5mV

Max Error 14 output voltage + 20mV

Update rate 480 samplessec

Output Load 2000Ω

Power Battery Two Alkaline D cells

Battery life 400 hours typ

USB 5V 100mA

Operational Environment Temperature 0-50

Humidity Up to 90 Non-condensing

Case Aluminum Alloy

Size and Weight 228times152times152(mm) 20(kg)

Table 3-2 Vishay Micro-Measurements Model P3 Strain Indicator and Recorder Specs

45

323 Strain Gauge

The strain gaugersquos main basic principle is to use a resistancersquos characteristics to measure the strain

The inside connections of the strain indicator are shown in figure 3-5

Fig 3-5 Inner Connections

As shown above this is a quarter-bridge connection We connect equal-length 3 wires to the 2

connections allowed by the strain gauge wire 1 and 3 can be used to cancel out the effects of temperature

to the resistance and because of the addition of wires 1 and 3 wire 2 can directly measure the experiment

results from the strain gauge and therefore the strain developed with no influence of temperature

If there were no two measuring leads then the relations will be

R 4 =R g +2R L

Where Rg is the Strain Gauge Value and RL is the wire resistance then

4

4

R

R=

Lg

g

RR

R

2

=

gL

gg

RR

RR

21

amp

4

4

R

R=

g

g

R

R(1- L)

Where L is the Signal Loss Factor and so

L =gL

gL

RR

RR

21

2

g

L

R

2R if

g

L

R

2Rltlt1

46

(Actual Value R g =120R L =08g

L

R

2Ris always much smaller than 1)

R 4 =R g +2R LR 2 =R 3 =rR gR 1 =R g 32 RR =0

V 0 =V 2)1( r

r

(

4

4

R

R-

1

1

R

R)

The first term describes loss attenuation effects second term describes loss of balancing capabilities

effects

V 0 =V 2)1( r

r

[

)2

(Lg

g

RR

R

+

T

Lg

g

RR

R

)

2( + T

Lg

L

RR

R

)

2

2( -(

g

g

R

R) T ]

The first term describes loss attenuation effects and loss of balancing capabilities effects the second

third and fourth terms describe the temperature effects on the wire

For the three-wire method we have

L =gL

gL

RR

RR

1

g

L

R

R if

g

L

R

Rltlt1

V 0 =V 2)1( r

r

[

)(Lg

g

RR

R

+

T

Lg

g

RR

R

)( + T

Lg

L

RR

R

)

2( -

T

Lg

g

RR

R

)( - T

Lg

L

RR

R

)

2( ]

V 0 = V2)1( r

r

)(

Lg

g

RR

R

In the last four terms inside parenthesis we can see the effects of temperature being cancelled out and the

effect on first term is not great so this is the reason why in our research we use three wires

47

324 Specimen Measurements

The tensile specimens used in this research are compliant of ASTM E8 Tensile parameters as shown

in figure 3-6

Fig 3-6 Tensile Specimen

Diameter

D(mm)

Gauge

Length

G(mm)

Smallest

Arc

Radius

R(mm)

Shortest

Area

A(mm)

Total

Length

L(mm)

Clamping

Area

Length

B(mm)

Clamping

Area

Diameter

C(mm)

Bar 125 02 625 01 gt10 gt75 ~ 145 ~ 35 20

Table 3-3 Specifications for Round Bar

33 Experiment Procedure

1 Attaching the Strain Gauge to the Tensile Specimen

(1) Prepare 1 ASTM E8 compliant tensile specimen round bar as shown in figure 3-7

(2) Prepare Strain Gauge as those described in table 3-4

(3) Prepare other consumables and adhesive agent such as epoxy adhesive or

cyanoacrylate adhesive as shown in figure 3-8

48

Fig 3-7 Actual Tensile Specimen

Fig 3-8 Other Materials Used (Such as Alcohol gauze transparent tape adhesive)

Gage Type

EA-06-120LZ-120E

Resistance in ohms at 24∘C

1200plusmn03

Gage Factor at 24∘C

2075plusmn05

Transverse Sensitivity at 24∘C

(+07plusmn02)

Table 3-4 Specifications for Strain Gauge

2 Attaching Strain Gauge

As shown in following figures we shall explain the attachment of the strain gauge

(1) Use sand paper and a rasp to clean thoroughly the surface where the strain gauge will be

attached to

49

(a)

(2) Use alcohol to wash the surface where the strain gauge will be attached and use gauze to rub

it off

(b)

(3) Find a clean surface and clean it with alcohol and gauze

(c)

(4) Place the strain gauge in the clean surface Use a piece of transparent tape on top of the strain

gauge after securely placed rip it off the surface carefully

50

(d)

(5) Use a piece of white paper to mark the place where the strain gauge will be attached and in

this way we can make sure that the strain gauge will be placed as horizontally and vertically

correct as possible

(e)

(6) In the place where we had our mark place the strain gauge

(f)

(7) Carefully lift one side of the tape and apply some of the adhesive agent to both the strain

gauge and specimenrsquos surface

(g)

51

(8) We need to make sure that the gauge and the specimen will be firmly attached so we gently

apply pressure with our thumb

(h)

(9) After the adhesive is fully dry we can carefully rip off the tape

(i)

(10) We need to do the whole process twice one for the horizontally placed strain gauge and one

for the vertically placed strain gauge

52

(j)

(11) We now proceed to solder the wires to the strain gauge

(k)

(12) After soldering we use a Volt Multimeter to measure that there is no contact between wires

If there is none then the specimen is ready for testing

(l)

(13) We now need to measure a 5cm distance and mark it to check and compare the elongation

before and after the tensile testing

(m)

53

Fig 3-9 Specimen-Strain Gauge Process

3 Tensile Test

(1) Enter the computer application that controls the tensile testing machine

(2) Turn on the tensile testing machine main switch

(3) Adjust the hydraulic pump to go back to its original position

(4) Bring the lowering motor down to a distance enough so as to attach the tensile specimen to the

system open the clamps and secure the specimen

(a)

(5) Connect all the necessary wires to the strain indicator equipment

54

(b)

(6) Start the ascending motor and wait for the expansion

(c)

Fig 3-10 Specimen-Tensile Testing Process

4 Start the Test

(1) Enter the software application and enter some variables needed for the experiment in the

specific screen

(2) Go back to the main screen and press the [測試] (measure) button to start the test and auto

recording in the software

(3) After the specimen breaks the mechanical device will automatically stop and ask the user to

enter the total displacement We take out the specimen from the testing machine and adjust the

machinersquos position back to its original position

(4) Save the results information

(5) Record the results from the strain indicator

34 Results

From this experiment we can get the Poissonrsquos Ratio Youngrsquos Modulus and Yield Strength etc and

because of the slippage phenomenon in the clamp at the moment of the test then the Elastic Limit will

display some yield phenomena So omit any undesirable results we just take the Yield portion of the

results as reference

In the process of the experiment the most important part to attend to is the attaching of the strain

gauge because the gaugersquos purpose is to measure the strain developed during the test and this strain

might be very small If the gaugersquos angle change during the test ie is not well attached this will affect

the accuracy of the measurements of Poissonrsquos ratio and Youngrsquos modulus

55

The materials provided by the manufacturer are SUM 23 and SUM 43 steel round bars and these two

types of materials have been through different heat treatment processes so they can be sub-divided

further into untreated material heat-treated material and black surface heat treated material for the two

materials with heat treatment the treatment process and finished are different In the end we only have

the mechanical properties that were calculated after our research of these materials

All of the specifications are identical to those shown in figure 3-6

341 SUM 23

Fig 3-11 SUM 23 Untreated Material

Number 7 10

Hardness(HRB) 74 75

Yield Stress (MPa) 448 440

Tensile Strength (MPa) 544 560

Poissonrsquos Ratio 029 027

Youngrsquos Modulus (GPa) 203 210

Cut-off Area Shrinking () 42 41

Elongation () 1125 1011

Table 3-5 Mechanical Properties of SUM 23 Untreated

56

Stress-Strain Diagram

(a)

(b)

57

Fig 3-12 Stress-Strain Diagrams for (a) 7 Round Bar and (b) 10 Round Bar

Cut-Off Area

(a)

(b)

Fig 3-13 Cut-Off Area of (a) 7 Round Bar and (b) 10 Round Bar

58

SUM 23 Nickel Round Bar

Fig 3-14 SUM 23 Nickel Material

Number 1 2 3 4

Hardness(HRB) 48 50 49 48

Yield Stress (MPa) 370 370 380 400

Tensile Strength (MPa) 455 451 450 450

Poissonrsquos Ratio 028 046 029 026

Youngrsquos Modulus (GPa) 243 303 246 206

Cut-off Area Shrinking () 803 803 726 601

Elongation () 566 65 602 647

Table 3-6 Mechanical Properties of SUM 23 Nickel

59

Stress-Strain Diagram

(a)

60

(b)

(c)

(d)

61

Fig 3-15 Stress-Strain Diagrams for (a) 1 Round Bar (b) 2 Round Bar (c) 3 Round Bar and (d)

4 Round Bar

Cut-Off Area

(a)

(b)

62

(c)

(d)

Fig 3-16 Cut-Off Area of (a) 1 Round Bar (b) 2 Round Bar (c) 3 Round Bar and (d) 4 Round

Bar

63

SUM 23 Black Surface Round Bar

Fig 3-17 SUM 23 Black Surface Material

Number 1 2 3

Hardness(HRB) 51 50 51

Yield Stress (MPa) 378 371 369

Tensile Strength (MPa) 467 465 464

Poissonrsquos Ratio 03 016 04

Youngrsquos Modulus (GPa) 215 266 266

Cut-off Area Shrinking () 986 94 848

Elongation () 748 805 761

Table 3-7 Mechanical Properties of SUM 23 Black Surface Material

64

Stress-Strain Diagram

(a)

(b)

65

(c)

Fig 3-18 Stress-Strain Diagrams for (a) 1 Round Bar 2 Round Bar and (c) 3 Round Bar

Cut-Off Surface

(a)

66

(b)

(c)

Fig 3-19 Cut-Off Surface of (a) 1 Round Bar 2 Round Bar and (c) 3 Round Bar

67

342 SUM 43

Fig 3-20 Untreated SUM 43 Untreated Material

Number 1 5

Hardness(HRB) 76 75

Yield Stress (MPa) 572 594

Tensile Strength (MPa) 743 785

Poissonrsquos Ratio 027 029

Youngrsquos Modulus (GPa) 200 202

Cut-off Area Shrinking () 338 2944

Elongation () 857 894

Table 3-8 Mechanical Properties of SUM 43 Untreated

68

Stress-Strain Diagrams

(a)

(b)

Fig 3-21 Stress-Strain Diagrams for SUM 43 (a) 1 Round Bar and (b) 5 Round Bar

69

Cut-Off Area

(a)

(b)

Fig 3-22 Cut-Off Area of SUM 43 (a) 1 Round Bar and (b) 5 Round Bar

70

SUM 43 Nickel Round Bar

Fig 3-23 SUM 43 Nickel Material

Number 4 5

Hardness(HRB) 51 50

Yield Stress (MPa) 1580 1544

Tensile Strength (MPa) 1639 1625

Poissonrsquos Ratio 03 028

Youngrsquos Modulus (GPa) 194 201

Cut-off Area Shrinking () 1697 137

Elongation () 376 265

Table 3-9 Mechanical Properties of SUM 43 Nickel

71

Stress-Strain Diagrams

(a)

(b)

Fig 3-24 Stress-Strain Diagrams for (a) 4 Round Bar and (b) 5 Round Bar

72

Cut-Off Area

(a)

(b)

Fig 3-25 Cut-Off Area of (a) 4 Round Bar and (b) 5 Round Bar

73

SUM 43 Black Surface Material

Fig 3-26 SUM 43 Black Surface Material

Number 3 5

Hardness(HRB) 56 56

Yield Stress (MPa) 1416 1361

Tensile Strength (MPa) 1591 1402

Poissonrsquos Ratio 029 031

Youngrsquos Modulus (GPa) 200 202

Cut-off Area Shrinking () 139 124

Elongation () 24 24

Table 3-10 Mechanical Properties of SUM 43 Black Surface Material

74

Stress-Strain Diagrams

0 2 4 6 8 10 12 14

-200

0

200

400

600

800

1000

1200

1400

1600

1800

應力 (MPa)

應變()

(a)

0 2 4 6 8 10

-200

0

200

400

600

800

1000

1200

1400

1600

應力

(MPa)

位移 ()

(b)

Fig 3-27 Stress-Strain Diagrams for (a) 3 Round Bar and (b) 5 Round Bar

(Note These curves were formulated using Visual Solutions Inc VisSim Software)

75

Cut-Off Area

(a)

(b)

Fig 3-28 Cut-Off Area of (a) 3 Round Bar and (b) 5 Round Bar

76

The force value (N) was retrieved from the Universal Testing Machine

The Poissonrsquos Ratio (ε) is calculated as

ε =

the values for the Poissonrsquos Ratio are in average around 0297

The Youngrsquos Modulus (E) is calculated as

E =

Where

Stress =

Cross-sectional Area =

where D is the Diameter

The value for D was in average around 1258 mm

The values shown by the computer because there is Slippage phenomena between the Clamp and the

specimen will not be taken into consideration for the elongation strain and Youngrsquos modulus and we will

refer to the values that we have meticulously calculated

77

Chapter 4 AR COATING IN DEPTH

41 Experimentrsquos Purpose and Principles

By means of a vacuum chamber and several other instruments we intend to apply Anti-Reflective

Coating using deposition process to a laser diode and in this way reduce its refraction so as to make it

lose less light in the process of amplification and we can control certain wavelengths we want produced

for certain desired applications in our case we are attempting to re-create a Bose-Einstein Condensate

An optimal BEC apparatus is shown in figure 4-1

Fig 4-1 BEC Apparatus

The main point of this experiment is to build a vacuum chamber system attach all the instrumentation

needed (Vacuum pump deposition meter and voltmeter) and use it to apply AR coating to a laser diode

After we have accomplished the AR coating other team will be in charge of designing the BEC apparatus

and use the results of our research

78

42 Experimentrsquos Equipment

421 Vacuum Chamber

For this research we designed a vacuum chamber whose main body is shown in figure 4-2 Its

dimensions are

Width 240 mm

Length 240 mm

Height 200 mm

Outer Diameter 4 in

Inner Diameter 15 in

Fig 4-2 Vacuum Chamber Main Body

The chamber is made up of 6 pass ways pass way A is the connection with the Laser Deposition

Equipment pass way B is the connection with the Turbo Pump and pass way C is for the connection with

the Deposition Source

A

C

B

79

Pass way C is for the deposition source as mentioned above This is a system where a thermal

resistance is heated by passing a high current through it which heats up a filament boat (made of tungsten)

where the material to be evaporated is place We control the temperature as such that the material will

evaporate and the heat will not cause the filament boat to crack

Because P = Isup2 R (where P is power I is current and R is resistance) to avoid the current to flow

where it is not desired we decided that the material for the Thermocouple shown in figure 4-3 should be

Copper ᴓ 63 mm We choose it that way because Copper has very good heat dissipation characteristics

and the resistance value is low It can reduce the value of the current enough to make the thermocouple to

create heat

Fig 4-3 Thermocouple

To the thermocouple we attach the tungsten filament boat We need to take notice of materials to be

used in this design because when using high current the tungsten filament boar will heat up and so the

material must be able to keep up with the heating potential of tungsten and has a low coefficient of heat

dissipation to avoid the tungsten to fail when heating up and therefore not evaporating Considering all

this we decide to use Stainless Steel

Because this clamp will be assembled inside the chamber after many revisions it was determined it

will have the shape shown in figure 4-4

Fig 4-4 Filament Boat Clamp Design

80

For the tungsten filament boat we bought the product from a distributor The dimensions are

Length 100 mm

Width 10 mm

Height 1 mm

Our thermocouple is 15 in but the pass way C is 4 in so we need to attach a Flange that connects

15in to 4in Because these specifications are quite difficult to achieve by Milling we had to use

electrical wire cutting

For the laser clamping system where the laser that is going to be AR coated will be placed will be

connected to pass way A the assembly is shown in figure 4-5 below

Fig 4-5 Cover Assembly

For this design we used an O-ring instead of a gasket so as to save time The design of the assembly

where the laser will be placed is shown in figure 4-6

Fig 4-6 Upper Cover Inner Assembly

D

E

F

81

Point D is the plate in the assembly where the laser diode will be fixed Because of the easy

processing we decide to use Aluminum and it is screwed to the top cover Point E is the connection for

the Quartz crystal resonator and it is designed in the same as point F in this way the results of the quartz

microbalance system will be more accurate in real time Point F is the final resting place for the laser

diode We use a Thor Labs Base with dimensions of ᴓ 9mm and ᴓ 56mm for two different size laser

diodes It just needs to be plugged in for easy installation

From figure 4-6 we know that the system needs signal system connections and because of the

change in temperature inside the chamber this could affect the functioning of the quartz microbalance so

we also need to install water tubes for cooling This is shown in figure 4-7 below

Fig 4-7 Diagram of Upper Cover Connections

In figure 4-8 we show the Feed through connections and their functions

Fig 4-8 Feed through Diagram

82

1 SQM-160 wire 5 Laser Connection 1 (Vin)

2 SQM-160 (G) 6 Laser Connection 2 (G)

3 K-Type-1 7 Laser Connection 3 (PD)

4 K-Type-2 8 Not In Use

The fully assembled chamber is shown in figure 4-9

Fig 4-9 Fully Assembled Chamber

422 Quartz Crystal Microbalance

For measuring the deposition on our target for coating we used the Inficon SQM-160 RateThickness

Monitor It is an easy to use instrument for measuring many types of thin-film coatings as shown in

figure 4-10

(a) Front Panel (b) Back Panel

Fig 4-10 Inficon SQM-160

83

Table 4-1 shows the technical specifications for this equipment

Number of sensors 2 Standard 4 additional optional

Sensor Frequency Range 40 MHz ~ 60 MHz

Reference Frequency Accuracy 002

Thickness Display Resolution 1 Aring

Thickness Resolution 015 Aring (Std) 0037 Aring (Hi Res)

Density of Stored Films 05-9999 gmcc

Tooling 10-399

Z-Factor 010-1000

Final Thickness 0000-9999k Aring

Measurement Period 15 to 2 sec

Simulation Mode Yes

Frequency Mode Yes

Rate Resolution 011 Arings

Dual Crystal Yes

Etch Mode Yes

Crystal Tooling 10-399

Crystal Fail Min Max 40 to 60 MHz 41 to 61 MHz

Power 100-120 200-240~plusmn10 nominal 20W

Operation Environment 0degC ~ 50degC

0 ~ 80 RH non-condensing

0 ~ 2000 meters

Class 1 Equipment

Pollution Degree 2

Rack Dimensions 885mm x 2127mm x 1969mm

Weight 27 kg

Table 4-1 Inficon SQM-160 RateThickness Monitor Specs

84

To the SQM-160 we need to connect an Oscillator We use the Sigma Instruments Remote Oscillator

Ser No 2 268 as shown in figure 4-11

Fig 4-11 Sigma Instruments Remote Oscillator

The connections diagram is shown in figure 4-12

Fig 4-12 SQM-160 Connections Diagram

85

423 Turbo Pump

For our experiments we used the Pfeiffer TCP 015 Electronic Drive Unit shown below in figure 4-13

Table 4-2 shows the technical specifications for this equipment

(a) Front Panel (b) Back Panel

Fig 4-13 Pfeiffer TCP 015 Electronic Drive

Connection Voltage (100V) 90-112

Mains Frequency 5060 Hz

Start-up Current 22 A

Nominal Frequency 1500 Hz

Rotation Speed 10V = 1500Hz plusmn2

Analog Output Current 10 V = 25 A plusmn 5

Rotation Speed Switchpoint 750 Hz

Works Setting 8 min

Permissible Ambient Temperature 0degC ~ 40degC

Dimensions Front Panel 1285mm x 1063mm

Insertion Length 227mm

Weight 27 Kg

Table 4-2 Pfeiffer TCP 015 Electronic Drive Specs

86

The connections diagram is shown in figure 4-14

Fig 4-14Connections Diagram for Pfeiffer TCP 015

To measure the pressure inside the chamber we use the Granville Phillips 375 Convectron Vacuum

Pressure Controller shown in figure 4-15

(a) Front Panel (b) Back Panel

Fig 4-15 Granville Phillips 375 Convectron

87

Its dimensions are shown in figure 4-16

Fig 4-16 Dimensions of Convectron

Table 4-3 shows the technical specifications for this equipment

Table 4-3 Granville Phillips 375 Convectron Vacuum Pressure Controller Specs

88

424 Multimeter

For our experiment we used the Keithley 2000 Digital Multimeter as shown in figure 4-17

(a) Front Panel (b) Back Panel

Fig 4-17 Keithley Model 2000 6-12-Digit Digital Multimeter

Its technical specifications are shown in table 4-4

Table 4-4 Keithley Model 2000 6-12-Digit Digital Multimeter Specs

89

43 Experiment Procedure

1 Connecting together the equipment and the chamber

(1) We first connect the resonator to the thickness monitor and connect the other side to the

chamber

(2) We now connect the flexible tubes to the turbo pump on one side and to the chamber on the

other

(3) We need to check that tubes are tightly connected to avoid any leaks in the vacuum pumping

process which will not allow us to get to our goal of Torr As shown in figure 4-18

(4) Connect the convectron to the system as shown in figure 4-19

Fig 4-18 checking for leaks using alcohol

Fig 4-19 Convectron attached to System

90

(5) Attach the clamps of the Multimeter to the bottom of the chamber as shown in figure 4-20

(6) Place the Quartz crystal in place

(7) Close tight vacuum chamber

(8) Connect all electrical appliances to power source

Fig 4-20 Multimeter Connections

2 Starting up the System

(1) We turn on all the devices as such Check all systems are ready to function Reset all values

that might be left over from previous tests

(2) Start the thickness monitor and set all values for this experiment In our case we got to testing

the system but not actual coating So we used the simulation mode of the thickness monitor as

shown in figure 4-21

Fig 4-21 Simulation Mode

91

(3) Start the turbo pump Make sure the lid on the vacuum chamber is tightly closed

(4) Start convectron and record initial pressure

(5) Start Multimeter and record initial current

3 Coating Process

(1) If we have the deposition material inside the filament boat the power source for the high

current must be started as well

(2) Record all initial values for thickness current pressure

(3) For an ideal experiment we need a thickness of around 101 nm a pressure of Torr and

a current of 300 A

44 Results

From previous experiments we have shown that we can turn a LED into a laser by means of AR

Coating In figure 4-22 shown below we can compare the actual results of a Diode before and after AR

coating From the blue line we can see that when the diode is at a current of 15mA its light will change

from LED to laser and if we look at the red line its critical current is around 30 to 35 mA

Fig 4-22 AR Coating Comparison for Laser Diodes

This means that the light emitted is not as strong as if the diode had been coated because inside the

chamber there must be some excitation first so the reflectivity of both sides inside the diode must be high

So because of the coating in one of the sides we have opened a door and let the light come out so the

critical current is risen as such and will be higher value than that of before the coating

92

In the following figures we can see the difference between before and after coating in a material The

thickness is around 1016 nm for this material

Fig 4-23 Before Coating

Fig 4-24 After Coating

93

Chapter 5 CONCLUSIONS AND RECOMMENDATIONS

51 Conclusions

For the first part of this independent study taking into consideration the data that came out of our

research and that sent by the provider we can say

1 SUM 23 after heat treatment will unexpectedly develop cracking in the middle of the tensile

testing process and suddenly break

2 Itrsquos possible that in the process of heat treatment to the SUM 23 material the treatment was not

uniform and this will create a pre-loaded moment force on one side that pushes on the other side

of the specimen resulting in material deformation

3 In the process of attaching the strain gauges to the materials it is very easy to make errors due to

poor adhesion or sudden removal in the tensile testing process

For our second part of the independent study the following can be made

1 At the beginning of this independent study we had no idea what Bose-Einstein Condensate was

or what was its purpose After much literature we finally comprehended the basic principles to

put into practice for our research

2 Our systemrsquos basic working principles and equipmentrsquos complexity are a little difficult to grasp

but hopefully we were able to understand enough of it

3 Theoretically from relation between the power and current we can know the advantages and

disadvantages of AR Coating

4 We were able to assemble the system and run test on its functions Even though we were able to

do this there is still much more work left to do with this system

52 Recommendations

For the Tensile Testing the following can be said

1 Ask the provider to check on the process of heat treatment on the SUM 23 material and give

them the information we have gathered through our test so they can correct for the mechanical

properties found if any change is needed

2 To avoid the problem of the inaccuracy of the poor adhesion of strain gauges we can attach

multiple strain gauges to the same one specimen so as to correlate data and improve our results

For the AR Coating the following can be said

1 We need to make sure that there are no physical defects on the main body of the chamber so as to

achieve maximum efficiency in the vacuum process If there was then the vacuum will arrive to

certain point and then start to decrease

2 It would be preferable to add some sort of visual aid that will allow the user to check the inside of

the chamber without actually opening it This will help us determine at what times we should

manipulate the current to better evaporate the substrate

94

REFERENCES

[1] A L Window Strain Gauge Technology Elsevier Applied Science London and New York 2nd

Edition 1992

[2] CC Perry and HR Lissner Strain Gauge Primer McGraw-Hill Book Co Inc New York 1955

[3] James W Dally William F Riley McGraw-Hill 1978

[4] University of Colorado Boulder BEC - What is it and where did the idea come from

httpwwwcoloradoeduphysics2000becwhat_is_ithtml

[5] Ultraslow Light amp Bose-Einstein Condensates Two-way Control with Coherent Light amp Atom

Fields Harvard Hau Lab Dr Lene Vestergaard Hau Optics amp Photonics News 16 1995

[6] The Art of Taming Light Ultra-slow and Stopped Light Harvard Hau Lab Dr Lene

Vestergaard Hau Europhysics News 2004

[7] Nonlinear Optics Shocking Superfluids Harvard Hau Lab Dr Lene Vestergaard Hau Nature

Physics 2007

[8] Model P3 Strain Indicator and Recorder Instruction Manual Vishay Micro-Measurements 2005

[9] Granville-Phillips Series 375 Convectron Vacuum Gauge Controller Instruction Manual Brooks

Automation 2008

[10] Effect of Film Thickness on the Validity of the Sauerbrey Equation for Hydrated Polyelectrolyte

Films Vogt Lin Wu White 2004

[11] Quartz Crystal Microbalance Study of DNA Immobilization and Hybridization for DNA Sensor

Development Chang Zhao 2008

[12] Installation of Strain Gages with SR-4 PrecoatAdhesive Vishay Micro-Measurements 2005

[13] Strain Gauge Measurement ndash A Tutorial National Instruments 1998

[14] Correlation between Vickers Hardness Number and Yield Stress of Cold-Formed Products

Yavuz Tekkaya

[15] httpsenwikipediaorg

Page 8: PC Hinge Materials Testing and AR Laser Diode Coating

8

LIST OF FIGURES

Fig 1-1 Notebook Computer Hingehelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 11

Fig 1-2 Basic Structure of Laserhelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 11

Fig 1-3 Comparison between LED and Laser Diodehelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 12

Fig 1-4 External Cavity Designhelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 12

Fig 2-1 Stress-Strain Curvehelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 14

Fig 2-2 Stress-Strain Curve Comparison on Metalshelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 15

Fig 2-3 Basic Structure of Strain Gaugehelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 17

Fig 2-4 Strain Gauge Attached to Wheatstone Bridgehelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 18

Fig 2-5 Brinell Indentationhelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 18

Fig 2-6 Brinell Hardness Testerhelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 18

Fig 2-7 Rockwell Indentationhelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 19

Fig 2-8 Rockwell Hardness Testerhelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 19

Fig 2-9 Vickers Indentationhelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 22

Fig 2-10 Vickers Hardness Testerhelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 22

Fig 2-11 Bose-Einstein Condensate at different scaleshelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 23

Fig 2-12 Super Conductorhelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 24

Fig 2-13 Simple Model for Light in Glass Mediumhelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 25

Fig 2-14 Simple Model for Light in Glass Medium after AR Coatinghelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 26

Fig 2-15 Light Passing through AR Coating and Glasshelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 27

Fig 2-16 Lens without and with AR Coatinghelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 27

Fig 2-17 Laser Diodehelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 28

Fig 2-18 Tunable Laser Basic Configurationhelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 28

Fig 2-19 Light Spectrumhelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 29

Fig 2-20 Front and Back Panel of SQM-160helliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 29

Fig 2-21 QCM Crystalshelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 31

Fig 2-22 SQM-160 Oscillatorhelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 31

Fig 2-23 Oscillator Circuithelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 32

Fig 2-24 Vacuum Evaporation Systemhelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 39

Fig 2-25 Turbo Pumphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 39

Fig 2-26 Control and Measurement Equipmenthelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 40

Fig 2-27 Complete Systemhelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 40

Fig 3-1 Universal Testing Machinehelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 41

Fig 3-2 Diagram for System Connectionshelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 42

Fig 3-3 Input Connections for Strain Gaugehelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 43

Fig 3-4 Vishay Micro-Measurements Model P3 Strain Indicator and Recorderhelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 43

Fig 3-5 Inner Connectionshelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 45

Fig 3-6 Tensile Specimenhelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 47

Fig 3-7 Actual Tensile Specimenhelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip47

Fig 3-8 Other Materials Usedhelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 48

Fig 3-9 Specimen-Strain Gauge Processhelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 49

Fig 3-10 Specimen-Tensile Testing Processhelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 53

9

Fig 3-11 SUM 23 Untreated Materialhelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 55

Fig 3-12 Stress-Strain Diagrams for 7 and 10 Round Barhelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 56

Fig 3-13 Cut-Off Area of 7 and 10 Round Barhelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 57

Fig 3-14 SUM 23 Nickel Materialhelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 58

Fig 3-15 Stress-Strain Diagrams for 1 2 3 and 4 Round Barhelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip60

Fig 3-16 Cut-Off Area of 1 2 3 and 4 Round Barhelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 62

Fig 3-17 SUM 23 Black Surface Materialhelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 63

Fig 3-18 Stress-Strain Diagrams for 1 2 and 3 Round Barhelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 65

Fig 3-19 Cut-Off Area of 1 2 and 3 Round Barhelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 66

Fig 3-20 SUM 43 Untreated Materialhelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip67

Fig 3-21 Stress-Strain Diagrams for 1 and 5 Round Barhelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 68

Fig 3-22 Cut-Off Area of 1 and 5 Round Barhelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 69

Fig 3-23 SUM 43 Nickel Materialhelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 70

Fig 3-24 Stress-Strain Diagrams for 4 and 5 Round Barhelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 71

Fig 3-25 Cut-Off Area of 4 and 5 Round Barhelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 72

Fig 3-26 SUM 43 Black Surface Materialhelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 73

Fig 3-27 Stress-Strain Diagrams for 3 and 5 Round Barhelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 74

Fig 3-28 Cut-Off Area of 3 and 5 Round Barhelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 75

Fig 4-1 BEC Apparatushelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 77

Fig 4-2 Vacuum Chamber Main Bodyhelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 78

Fig 4-3 Thermocouplehelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip79

Fig 4-4 Filament Boat Clamp Designhelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 79

Fig 4-5 Cover Assemblyhelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 80

Fig 4-6 Upper Cover Inner Assemblyhelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 80

Fig 4-7 Diagram of Upper Cover Connectionshelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 81

Fig 4-8 Feed Through Diagramhelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 81

Fig 4-9 Fully Assembled Chamberhelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 82

Fig 4-10 Inficon SQM-160helliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 82

Fig 4-11 Sigma Instruments Remote Oscillatorhelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 84

Fig 4-12 SQM-160 Connections Diagramhelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 84

Fig 4-13 Pfeiffer TCP 015 Electronic Drivehelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 85

Fig 4-14 Connections Diagram for Pfeiffer TCP 015helliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 86

Fig 4-15 Granville Phillips 375 Convectronhelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 86

Fig 4-16 Dimensions of Convectronhelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 87

Fig 4-17 Keithley Model 2000 6-12-Digit Digital Multimeterhelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 88

Fig 4-18 Checking for Leaks Using Alcoholhelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 89

Fig 4-19 Convectron Attached to Systemhelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 89

Fig 4-20 Multimeter Connectionshelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 90

Fig 4-21 Simulation Modehelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 90

Fig 4-22 AR Coating Comparison for Laser Diodeshelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 91

Fig 4-23 Before AR Coatinghelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 92

Fig 4-24 After AR Coatinghelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 92

10

Chapter 1 INTRODUCTION

11 Motivation and Background

In response that new generation computers are gradually reducing their size the diameter of

the structures of the hinges used by NB computers must also follow but the hinge strength may

also become smaller due to the reduction of diameter and result in the phenomenon of

insufficient strength In addition the disk-type spring that is source of the torque may also be

insufficient due to the narrowing of the structure Therefore it is necessary to direct a structural

analysis of the hinge for the existing laptops so that we can identify the stress concentration

point The stress concentration point is usually the point where material damage behavior is

encountered the easiest and if we can find the point where breaking occurs most often we can

improve the design of the existing structure to enhance the strength of the hinge structure

Second the structure of the hinge is too complicated the traditional mechanics of materials

analysis methods and formulas are no longer suitable for analysis of a wide arrange of hinge

design In recent years finite element analysis methods have been widely applied in various

fields such as electronics machinery aviation and so on

Therefore to meet the need of the industry and with the purpose of reducing design time

how to design a notebook computer hinge without compromising mechanical stability and

materialrsquos hardness which will operate equally under equal conditions In other words be able to

meet the needs of the size decreasing NB computers market as the needs for this kind of

accessories will increase in the near future If we take into consideration the traditional ways of

design we seek to reduce the costs of use of machinery and molding by applying Finite Element

Analysis methods to our study and also increase the flexibility of designing methods

The second project was brought in by Prof Chuang and it is to help in the further research of

the Bose-Einstein condensate This is a state of matter of a dilute gas weakly interacting bosons

(subatomic particles that obey the Bose-Einstein statistics) confined in an external potential and

cooled down to temperatures very near absolute zero (0 K or -27315deg C) Under these conditions

a large number of bosons occupy the lowest quantum state of the external potential at which

point quantum effects become apparent at macroscopic scale This state of matter was predicted

by Satyendra Nath Bose and Albert Einstein in 1924~1925 Then 70 years later the 1st gaseous

condensate was produced by Eric Cornell and Carl Wieman in 1995 at the University of

Colorado (Boulder) NIST-JILA lab and because of this along with Wolfgang Ketterle of MIT

they received the 2001 Nobel Prize in Physics

11

We wish to investigate the properties of Anti Reflecting Coating on laser diodes Hopefully

we will be able to achieve the desired effect of reducing the surface reflection coefficient and

find applications for it

12 Research Objective

We wish to analyze the normal composition of the notebook computerrsquos hinge at which

point in the assembly is clearly the weakest and at this time in the assembly the strength and

durability are influenced The main point is to see if we can affect the normal operation and work

life

The objective of this thesis is to present the results of the material properties under tensile

testing find the mechanical properties and after using finite element analysis determine what

material is the best for our purposes

Fig 1-1 Notebook Computer Hinge

For our second research we wish to produce and analyze laser diodes with anti-reflective

coating and test its properties and applications

When semi-conductor laser has been submitted to current it will produce resonance inside it

and light will be stimulated to come out Please refer to figure 1-2 for the basic structure of a

laser

Fig 1-2 Basic Structure of a Laser

1 Gain Medium

2 Laser Pumping Energy

3 High Reflector

4 Output Coupler

5 Laser Beam

12

But when the laser diode generates light but the laser diode canrsquot produce light on itself it

must wait for the current to be higher than certain value which is called the critical current Until

the light goes over this threshold then it is considered laser light if not it is just considered as a

common LED light source Please refer to figure 1-3

Fig 1-3 Comparison between LED and Laser Diode

As we can see from figure 1-3 all of the light that goes over the critical current is laser light

and so the external cavity semi-conductor laser that we built needs Anti-Reflective Coating

because the method we want to use needs an external cavity laser that has been covered with AR

Coating and a Diffraction Grating We use this configuration first by shooting the laser to the

grating and this will be shot back to the laser creating the external resonance cavity which is

shown in figure 1-4

Fig 1-4 External Cavity Design

13

Two configurations are shown the Littrow Configuration and the Littman-Metcalf

Configuration The Littrow configuration contains a collimating lens and a diffraction grating as

the end mirror The first order diffracted beam provides optical feedback to the laser diode which

has AR Coating The emission wavelength can be turned by rotating the diffraction grating A

disadvantage is that it also changes the direction of the output beam

In the Littman-Metcalf configuration the grating orientation is fixed and an additional mirror

is used to reflect the first order beam back to the laser diode The wavelength can be turned by

rotating that mirror This configuration offers a fixed direction of the output beam and also tends

to exhibit smaller line width as the wavelength selectivity is stronger A disadvantage is that

zero order reflection of the beam reflected by the tuning mirror is lost so that the output power is

less than that of a Littrow laser

13 Methodology

The aim of this research is to find the mechanical properties of materials after being

subjected to tensile testing through finite element analysis observations and determine what

material is best for our purposes taking into consideration the strength and durability of the

material among other properties to find use and applications for the AR coated laser diodes to

further improve the grasp of the Bose-Einstein condensation working principles

14 Organization of the Thesis

The research paper includes five chapters

1 Chapter 1 explains the motivation background objective and methodology of this study

2 Chapter 2 explains the working principles and basic knowledge needed to understand this

study

3 Chapter 3 explains the tensile testing in detail steps methods and results

4 Chapter 4 explains the AR coating in detail steps methods and results

5 Chapter 5 is the conclusions taken from the results shown in chapter 3 and 4 and

recommendations done after arranging and critical thinking

14

Chapter 2 BASICS THEORIES

21 Tensile Testing

After a specimen is tested with the use of tensile testing we can get the Stress-Strain Curve using the

relation between tension and displacement Typical curves are shown in Fig 2-1

(a) Ductile materials (b) Brittle materials

Fig 2-1 Stress-Strain Curve

The curve is unique for each material and is found by recording the amount of deformation at distinct

intervals of tensile or compressive loads Thanks to the use of the Stress-Strain curve we can get very

useful information such as

211 Youngrsquos Modulus (E)

As shown in Fig 2-1 as long as the external load is not greater than the Proportional Limit the Stress

(σ) and Strain (ε) remain as a linear relation fulfilling Hookersquos Law

σ = Eε

The slope is the constant factor the inverse of the modulus of elasticity E also called Youngrsquos

modulus When the external load goes over the proportional limit the stress-strain relationship doesnrsquot

follow the linear relation anymore but the deformation remains flexible When the load is released the

deformation is completely eliminated and the specimen goes back to its original state This is called

15

Elastic Deformation When the external load goes over the Elastic limit only then does the specimen

presents Plastic Deformation This type of deformation which is irreversible even when the load is

removed comes after the material does under elastic deformation so this means the object will first come

part way to its original shape Common metals and ceramics have roughly the same elastic limits

212 Yield Strength and Yield Point

Some materials display very evident yield phenomena while some materials donrsquot as shown in Fig

2-2 After we exceed the elastic limit if we continue to exert load when we arrive to a certain value

which differs under different materials and external conditions there is sudden decrease in stress and this

is called the Yield Strength and can be defined as the stress at which a material begins to deform

plastically using the equation

σyield =

Where P is the tension force and Ao is the original cut-off area

The stress remain at a certain value after the decrease but the strain increases this phenomena can be

easily appreciated when studying the behavior of common Carbon Steel Fig2-2 (a) but most metals (like

Aluminum Copper or High Steel Carbon) donrsquot display this kind of behavior as shown in Fig 2-2 (b)

Arriving to this point is very difficult and the most commonly used method for this is to add a 02 or

0002 offset yield strength to the curve This point is held constant on the strain axis of the curve and

from the 0002 position we draw a straight line parallel to the linear relationship line the point at where

this line and the stress-strain curve intercept is the point we take as the 02 offset yield strength

(a)Evident (b) Non-evident

Fig2-2 Stress-Strain Curve Comparison on Metals

16

213 Ultimate Tensile Strength and Breaking Strength

After materials undergo yield they keep lending strength and hardening phenomena occurs (work

hardening) on the material and the external load increases When it has reached the highest point this is

called the Ultimate Tensile Strength (UTS) as shown in Fig2-1 The UTS is defined as

σUTS =

Where Pmax is the load at the materialrsquos ultimate tensile strength point and Ao is the original cut-off

area For brittle materials the ultimate tensile strength is the most important mechanical property for

ductile materials the ultimate tensile strength is not commonly used for industrial and designing purposes

because upon arriving to this value the material already has forgone great plastic deformation After the

specimen goes through UTS there will be necking phenomena which is a mode of tensile deformation

where relatively large amounts of strain localize disproportionately in a small region of the material It

results from instability during tensile deformation when a materialrsquos cross-sectional area decreases by a

greater proportion than the material strain hardens The specimen continues to elongate until it finally

breaks and the load at this point is called Breaking Strength The breaking strength is defined as the

greatest stress in tension that a material is capable of withstanding without rupture

Where Pf is the load at the materialrsquos breaking strength point and Ao is the original cut-off area

214 Poissonrsquos Ratio (ν)

For elastic deformation when materials are compressed in one direction they tend to expand in the

other two directions perpendicular to the direction of compression This is called the Poissonrsquos Effect

The Poison Ratio is a measure of the Poissonrsquos effect It is the ratio of the fraction of expansion divided

by the fraction of compression for small values of these changes

ν=-

215 Strain Gauge Basic Principles

The strain gauge is a device used to measure the strain of an object Itrsquos an elongated metal resistor

which is attached to the specimen being measured and when the specimen is under strain and starts to

deform the strain gauge will have a change in the resistance With the change in value we can calculate

the elementrsquos strain or elastic modulus and the Poissonrsquos ratio

It takes advantage of the physical property of electrical conductance and its dependence on the

conductorrsquos geometry When the electrical conductor (the specimen being tested) is stretched within the

limits of elasticity such that it does not break or deform plastically it will become narrower and longer

17

which increases the electrical resistance through-out From the measured resistance of the strain gauge

the amount of stress may be inferred by using the relations

R=

Where R is the original resistance value is the electrical resistivity lo is the original length of the

conductor and Ao is the original cross sectional area of the conductor If after the application of tension

the change in length is Δl let the length of the specimen be l = l + Δlo and the tension is the same

through-out So

And the resistance is

The Gauge Factor is the ratio of relative change in electrical resistance to the mechanical strain in

other words it is the relative change in length It is defined as

The strain gauge was invented in 1938 by Edward E Simmons and Arthur C Ruge and the most

common type consists of an insulating flexible backing which supports a metallic foil usually made of a

brass-nickel alloy It is attached to the specimen by a suitable adhesive As the object is deformed the foil

also deforms and this causes the electrical resistance to change Then this is usually measured using a

Wheatstone bridge shown below and is related to the strain by the Gauge Factor

Fig2-3 Basic Structure of Strain Gauge

18

Fig 2-4 Strain gauge attached to Wheatstone bridge

22 Hardness Testing Basic Principles

221 Brinell Scale BHN

The Brinell Scale characterizes the indentation hardness of materials through the scale of penetration

of an indenter loaded on a material specimen The typical test uses a 10mm diameter steel ball as indenter

(usually of value equal to BHN450) with a 29kN force For softer materials smaller force is used The

indentation is measured and BHN is calculated using the relation

BHN =

radic

Where F is the applied force usually within the range of 100 250 500 750 1000 1500 2000 2500

and 3000 kgf D is the diameter of indenter usually within the range of 5mm or 10mm plusmn0005 margin

and d is the diameter of indentation usually around 2mm Its units are of Kgmmsup2 but are not normally

written

First proposed by Swedish engineer Johan August Brinell in 1900 it was the first widely used and

standardized hardness test in engineering and metallurgy although the large size of indentation and

possible damage to specimen limits its usefulness

Fig 2-5 Brinell Indentation Fig2-6 Brinell Hardness Tester

19

222 Rockwell Scale HR

The Rockwell scale is a hardness scale based on the indentation hardness of a material The Rockwell

test determines the hardness by measuring the depth of penetration of an indenter under a large load

compared to the penetration made by a preload The indenter is forced into the specimen under a

preliminary load When equilibrium is reached a measuring device follows the movements of the

indenter and responds to changes in depth of penetration of the indenter While the preload is still being

applied additional major load is applied resulting in increased penetration When equilibrium is reached

again the major load is removed but the preload is maintained Removing the major load allows partial

recovery and reduces the depth of penetration The permanent increase in depth of penetration resulting

from the application and removal of the major load is used to calculate the Rockwell number using the

relation

HR = E ndash e

Where E is a constant depending on the form of the indenter 100 units for diamond indenter and 130

units for steel ball indenter e is the permanent increase in depth of penetration due to the major load

measured in units of 0002mm

Fig 2-7 Rockwell Indentation

When testing materials indentation hardness is related linearly to the tensile strength The important

relation permits economically important nondestructive testing of bulk metal deliveries with lightweight

equipment like the Rockwell tester shown below in figure 2-7

Fig 2-8 Rockwell Hardness Tester

20

There are different scales denoted by a single letter that use different loads or different indenters

The result is a dimensionless number denoted as HR X where X will be the letter denoting the scale as

shown below in table 2-1

Table 2-1 Rockwell Hardness Test Scale

Differential depth hardness measurement was first conceived in 1908 by Viennese professor Paul

Ludwik It eliminated the errors associated with the mechanical imperfections of the system such as

backlash and surface imperfections in the specimen Rockwell testing has an advantage over Brinell

testing because the latter was slow itrsquos not useful on fully hardened steel and left too large an impression

to be considered nondestructive

The tester was co-invented by Hugh M Rockwell and Stanley P Rockwell The requirement for this

tester was to quickly determine the effects of heat treatment on steel bearing races

21

223 Vickers Hardness Test HV

This is a type of microindentation hardness test where a diamond indenter of specific geometry is

impressed into the surface of the test specimen using a known applied force ranging from 10 to 1000

grams This type of tests usually has forces of 2N and produce indentations of about 50μm They can be

used to observe changes in hardness on the microscopic scale It is difficult to standardize the

microhardness measurements because it has been found that the microhardness of almost any material is

higher than its macrohardness The values also vary with load and work-hardening effects of materials

The Vickers test is often easier to use than other hardness tests because the required calculations are

independent of the size of the indenter and the indenter can be used for all materials It can be used for all

metals and has one of the widest scales among hardness tests The unit of the Vickers test is denoted as

HV and can be converted to units of Pascal (Pa) but it is not a measurement of pressure The hardness

number is determined by the load over the surface area of the indentation and not the area normal to the

force

A square-based pyramid shaped diamond is use as the indenter It has been established that the ideal

size of a Brinell impression was 38 of the ball diameter As two tangents to the circle at the ends of a

chord 3d8 long intersect at 136plusmn05deg it was decided to use this as the angle of the indenter giving an

angle to the horizontal plane of 22deg on each side The HV number is determined by the ratio FA where F

is the force applied to the diamond in kgf and A is the surface area of the resulting indentation in mmsup2 A

can be determined by the relation

A =

Where A is the surface area of indentation and d is the average length diagonal left by the indenter

This can be approximated as

A =

Then the Vickers Number is

HV =

=

Vickers hardness number is reported as xxxHVyy or xxxHVyyzz (if duration of applied force differs

from 10s to 15s) where xxx are replaced by the hardness number yy is the load in kg and zz indicates

loading time The values are generally independent of test force

The test was developed in 1921 by Robert L Smith and George E Sandland at Vickers Ltd as an

alternative to Brinell method to measure the hardness of materials

22

Fig 2-9 Vickers Indentation Fig 2-10 Vickers Hardness Tester

23 AR Coating

231 Bose-Einstein Condensate

The Bose-Einstein Condensate or BEC is a state of matter of a dilute gas of bosons cooled to

temperatures very near absolute zero around 0K or -27315degC Under such conditions a large fraction of

the bosons occupy the lowest quantum state where the quantum effects become apparent on a

macroscopic scale This gave birth to the Bose-Einstein Statistics which are the rules that govern the

behavior at this state It is one of the two possible ways in which a collection of indistinguishable particles

may occupy a set of available discrete energy states The aggregation of particles in the same state

accounts for the cohesive streaming of laser light and the frictionless creeping of superfluid helium (an

application discussed later) Bose and Einstein recognized that a collection of identical and

indistinguishable particles can be distributed this way This theory applies only to those particles not

limited to single occupancy of the same state particles that do not obey the Pauli Exclusion Principle

restrictions Such particles are the Bosons named after the statistics that correctly describe their behavior

This phenomenon was first predicted by Satyendra Nath Bose around 1924 when he considered how

groups of photons behave He then asked Albert Einstein for help publishing his discoveries to which

Einstein agreed and gave follow up supporting these findings The resulting efforts became the concept of

a Bose gas governed by the Bose-Einstein Statistics described above Einstein demonstrated that cooling

bosonic atoms to a very low temperature would cause them to condense into the lowest accessible

quantum state resulting in a new form of matter

The first gaseous condensate we produced by Eric Cornell and Carl Wieman at the University of

Colorado at Boulder NIST ndash JILA lab sung a gas of rubidium atoms cooled to 170 nK which earned

them the 2001 Nobel Prize in physics together with Wolfgang Ketterle from MIT The transition to BEC

occurs below a critical temperature which for a uniform three dimensional gas consisting of

non-interacting particles with no apparent internal degrees of freedom is given by

23

Tc =

(

)

asymp 33125

Where Tc is the critical temperature n is the particle density m is the mass per boson h is the

reduced Planck constant k is the Boltzmann constant and ζ is the Riemann zeta function

There are two classes of elementary particles defined by whether their quantum spin is a nonnegative

integer or an odd half integer A Bose-Einstein Condensate is shown below in figure 2-11

Fig 2-11 Bose Einstein Condensate at different scales

Bosons are the particles whose quantum spin is a nonnegative integer (s = 0 1 2 etc) Examples of

bosons include fundamental particles (Higgs Boson Photons W and Z Bosons Gluons Gravitons etc)

composite particles (Mesons Hadrons Nuclei and Atoms of Carbon-12 and Helium-4) and

quasi-particles Bosons are considered force carrier particles The Bosons differ from Fermions in that

there is no limit to the number that can occupy the same quantum state This is called the Pauli Exclusion

Principle

The Pauli Exclusion Principle says that no two identical fermions may occupy the same quantum state

simultaneously in other words this means that the total wave function for two identical fermions is

anti-symmetric with respect to exchange of the particles This means that no two electrons in a single

atom can have the same four quantum numbers

Fermion is any particle characterized by Fermi-Dirac Statistics and follows the Pauli Exclusion

Principle described above Quarks Leptons and composite particles (Hadrons Nuclei and Atoms of

Carbon-13 and Helium-3) made of an odd number of these are considered Fermions It can be an

elementary particle such as the electron or a composite particle such as the protons Following the Pauli

24

Exclusion Principle only one fermion can occupy a particular quantum state at any given time If multiple

fermions have the same spatial probability distribution then at least one property of each fermion must be

different Fermions are usually associated with matter because composite fermions are key building

blocks of matter (neutrons and protons)

Fermionsrsquo behavior by the Fermi-Dirac Statistics which describes the energies of single particles in a

system comprising of many identical particles It applies to identical particles with half-odd integer spin

in a system of thermal equilibrium The particles in the system are assumed to have negligible mutual

interaction This allows the many-particle system to be described in terms of single-particle energy states

The result is the Fermi-Dirac distribution of particles over these states and includes the condition that no

two particles can occupy the same state which has considerable effect on the properties of the system

In quantum mechanics the position of an object is uncertain An object has a definite probability of

being at any given point in space This probability is encoded in the wave function mentioned earlier If

one concentrates a large number of identical bosons in a small region then it is possible for their wave

functions to overlap so much that the bosons lose their identity When this happens thatrsquos a Bose-Einstein

Condensate It is only possible at very low temperatures because at high temperatures the individual

bosons have small wave functions and move rapidly which causes them to fly apart

For now applications are still restricted because there are still some setbacks regarding BECs They

are extremely fragile they are being produced in small quantities with just a few million atoms at a time

and finally they can only be made from certain types of atoms Some examples are the atom laser Ketterle

in which a conventional light lase emits a beam of coherent photons this means they are all in phase and

can be concentrated to an extremely small bright spot BECs can slow down light as demonstrated by

Prof Lene Hau PhD in 2001 by the use of a superfluid [7] These manipulations could develop into

new types of telecommunications technology optical storage and quantum computing

BECs are related to super-fluidity and super-conductivity Super-fluidity is the state of matter in

which the behavior is that of a fluid with zero viscosity It was discovered in liquid helium but now it has

applications in astrophysics high-energy physics and theories of quantum gravity

Super-conductivity is a phenomenon of exactly zero electrical resistance and expulsion of magnetic

fields occurring in certain materials when cooled below a characteristic critical temperature A

super-conductor is shown below in figure 2-12

Fig2-12 Super Conductor

25

232 AR Coating Basic Principles

Anti-reflective (AR) coating is a type of optical coating applied to the surface of lenses and other

optical devices (in our case we planned to apply it to a laser diode) to reduce reflection This improves

the efficiency of the system since less light is lost The primary benefit is the elimination of the reflection

itself

When light the medium (glass) it will produce reflection if 100 of the light comes from the air and

enters the glass because therersquos a difference between the index of refraction some of the light will go out

and when the light is coming out of the glass into the air once again because of the difference between

index of refraction some of the light wonrsquot be able to pass through the medium

When the light makes the first trip into the glass there was a loss of about 4 in the reflection and

when the light makes the trip back outside there was another loss of about 4 so when we assume that

100 of the light interacts with the medium actually therersquos just about 92 acting (we neglect the light

absorbed by the glass around 05) To illustrate this idea please refer to figure 2-13

Fig 2-13 Simple Model for Light in Glass Medium

When we apply the AR Coating the light that enters will only have a loss of about 05 and when

making the trip back outside again only 05 of light is loss so we get the result of increasing the light

passing through up to 99 (again neglecting the light absorbed by the glass around 05) To illustrate

this idea please refer to figure 2-14

26

Fig 2-14 Simple Model for Light in Glass Medium after AR Coating

The AR Coating can reduce reflection of incoming light In the case that light hits perpendicular to

the surface of the medium the intensity of the reflection can be calculated using the Reflection

Coefficient

Where n0 and ns are the refractive indices of the first and second media respectively The value of R

varies from 0 (no reflection) to 1 (all light reflected) and is usually quoted as a percentage

Complementary to R is the transmission coefficient or Transmittance If absorption and scattering are

neglected then the value of Transmittance is always 1-R then if a beam of light with intensity I is

incident on the surface a beam of intensity RI is reflected and a beam with intensity TI is transmitted to

the medium

The optimal value is called the Optimal Index of Refraction and is described as

For glass with ns around 15 in air (n0 around 10) then the optimum refractive index will be n1 =

1225

To reduce the refraction in this case we now mean the one that is produced inside the chamber of the

Laser diode the easiest way is to apply a low reflectivity AR coating on the surface of the laser To

measure the appropriate thickness of the coating layer we can use the equations described above By

applying a coat exactly

thickness film we can assure that a certain wavelength is transmitted The

27

reflected waves from the back of the glass medium will be half a wavelength out of phase So they

interfere destructively Because all reflected waves are interfered the maximum amount of light passes

through the coating Please refer to figure 2-15 to illustrate this idea

Fig 2-15 Light Passing through AR Coat and Glass

The most common process to attain this final product is by vacuum deposition For the best coating

results we need to lower the pressure inside the vacuum system to torr

Fig 2-16 Lens without (Top) and With (Bottom) AR Coating

28

233 Laser Diode Basic Principles

A laser diode is a laser whose active medium is a semiconductor similar to that found in

light-emitting diodes (LEDs) Please refer to figure 2-17 The most common type of laser diode is formed

from a p-n junction and powered by injected electric current

Fig 2-17 Laser Diode

Laser diodes are formed by doping a very thin layer on the surface of a crystal wafer The crystal is

doped to produce the n-type region and a p-type region one above the other

By referring to figure 1-2 we can see the basic structure of a working laser When the laser diode has

a current passing through it the light will get excited inside its gain medium and then will start to

resonate this process is called pumping The current exceeds the critical current and then it comes out as

laser light Please refer to figure 1-3 Since we use an external cavity laser we need to apply the AR

coating to the diode and adjust a diffraction grating The laser light comes out the diode and bounces on

the grating making the resonance externally and this becomes the ldquocavityrdquo as shown in figure 2-18

Fig 2-18 Tunable Laser Basic Configuration

29

The most important feature of the external cavity laser is that we can adjust the wavelength easily just

by changing the diffraction gratingrsquos angle and in the end this is the output wavelength of the laser For

different wavelengths there will be different levels of visible light as shown in figure 2-19

Fig 2-19 Light Spectrum

234 Quartz Microbalance System

A Quartz Crystal Microbalance is an instrument that measures a mass per unit area by measuring the

change in frequency of a quartz crystal resonator The resonance is disturbed by the addition or removal

of a small mass due to oxide growthdecay or film deposition (which is the case in our study) at the

surface of the acoustic resonator The QCM can be used under vacuum in gas phase and more recently in

liquid environments It is useful for monitoring the rate of deposition in thin film deposition systems

under vacuum Frequency measurements are easily made with high precision

For our research we used the Sigma Instruments SQM-160 RateThickness Monitor shown in figure

2-20

Fig 2-20 Front and Back Panels of SQM-160

30

The microbalance uses Quartz as the resonator Quartz is one member of the family of crystals that

experience the Piezoelectric Effect

Piezoelectricity is the charge that accumulates in certain solid materials in response to applied

mechanical stress It means electricity resulting from pressure It was discovered in 1880 by Jacques and

Pierre Curie It is understood as the linear electromechanical interaction between the mechanical and the

electrical state in crystalline materials with no inversion symmetry It is a reversible process in that

materials exhibiting direct piezoelectricity also exhibit the reverse This means that the internal generation

of electrical resulting from applied mechanical force and vice versa

By using the piezoelectric effect we can probe as an acoustic resonance by electrical means Applying

alternating current to the quartz crystal induces oscillations This creates a shear wave We can use these

qualities to determine the resonance frequency at high accuracy

The frequency of oscillation of the crystal is partially dependent in the thickness of the crystal During

normal operation all the variables are held constant so a change in thickness correlates directly to a

change in frequency As mass is deposited or etched away the thickness increases or decreases and so the

frequency of oscillation changes accordingly With some simplifying assumptions the frequency change

can be quantified and correlated precisely to the mass change using the Sauerbreyrsquos Equation

Developed by G Sauerbrey in 1959 it is a method for correlating changes in the oscillation

frequency of a piezoelectric crystal with the mass deposited on it It is defined as below

Where f0 is the Resonant frequency Δf is the Frequency change Δm is the mass change A is the

piezoelectrically active area of the crystal q is the Density of quartz (2648 gcmsup3) and μq is the Shear

modulus of quarts(2947x gcmssup2)

Because the film is treated as an extension of thickness Sauerbreyrsquos equation only applies to systems

in which the following 3 conditions are met

Deposited mass must be rigid

Deposited mass must be distributed evenly

The frequency change

lt002

If the change is greater than 2 the Z-match method must be used to determine the change in mass

It is defined as

Where fL is the frequency of the loaded crystal fU is the resonant frequency Nq is the frequency

constant (1668x HzAring) Δm is the mass change A is the piezoelectrically active area of the crystal

31

q is the density of quartz Z is the method constant f is the density of film μq Is the shear modulus of

quarts and μf is the shear modulus of film

The Sauerbrey equation cannot be applied to systems under liquid medium

The crystals are seed crystals plated with gold on both top and bottom for applications A crystal is

shown in figure 2-21 The QCM consists of a thin piezoelectric plate with electrodes evaporated on both

sides Due to the piezoelectric effect AC voltage across the electrodes induces a shear deformation and

vice versa The electromechanical coupling provides a simple way to detect an acoustic resonance by

electrical means

The Z also called Z-factor is a constant value for different materials and it is shown together with the

density of different materials in table 2-2 below

Fig 2-21 QCM Crystals

The Oscillator of the SQM-160 is shown in figure 2-22 and the equivalent circuit for the Resonant

Oscillator is shown in figure 2-23

Fig 2-22 SQM-160 Oscillator

32

Fig 2-23 Oscillator Circuit

33

Table 2-2 Z-Ratios for Different Materials

Table 2-2 Continued

34

Table 2-2 Continued

35

Table 2-2 Continued

36

Table 2-2 Continued

37

Table 2-2 Continued

38

Table 2-2 Continued

235 Vacuum Chamber System

Vacuum Evaporation is the process of depositing thin films of materials onto surfaces The technique

consists of pumping a vacuum chamber to pressures of less than torr and heating a material to

produce a flux of vapor in order to deposit the material onto a surface The material to be vaporized is

typically heated until its vapor pressure is high enough to produce a flux several Angstrom per second by

using an electrically resistive heater or bombardment by a high voltage beam The process was invented

by Henri Nestle in 1886 for food industry

In here the system has been pumped to a vacuum of Torr When a high current is passed

through the filament boat the filament boat is heated over the desired metal evaporation temperature and

so evaporation starts When the evaporation process is finished and the metal cools down crystals

condensate in the surface of the wafer From the weight of the evaporated material the distance between

the filament boat and the wafer we are able to calculate the deposition thickness and we can also use the

mass detector follower like the Quartz crystal resonator microbalance system In the process of

evaporation we usually use a board in between the filament boat and the wafer This is because before we

arrive to the desired evaporation temperature there will be some impurities that will be vaporized in the

controlled environment so we first use a small current and the board in between to get rid of those

impurities and this raises the purity of the deposition material

39

A vacuum evaporation system is shown in figure 2-24

Fig 2-24 Vacuum Evaporation System

Rough Vacuum 760 ~ 1 torr

Medium Vacuum 1 ~ torr

High Vacuum ~ torr

Ultra-High Vacuum Lower than torr

Table 2-3 Classification of Vacuum

For our study we need to use a Turbo Pump A regular turbo pump is shown in figure 2-25

Fig 2-25 Turbo Pump

For our research we used the Pfeiffer TCP 015 Electronic Drive Unit and Granville Phillips 375

Convectron shown below in figure 2-26

40

Fig 2-26 Control and Measurement Equipment

The electronic drive controls the turbo pump and the Convectron measures the pressure inside our

chamber The turbo pump is a type of vacuum pump used to maintain high vacuum Most turbo pumps

are centrifugal When we start the pumping we need to use a mechanical pump so as to decrease the

pressure inside the system from constant atmospheric pressure to torr and then the use dispersion

pump to continue the vacuum until we get to the desired pressure We need to notice though when we

start the dispersion pump we canrsquot turn off the mechanical pump and they both need to run together If

we need to turn off the pumping we first turn off the dispersion pump wait for it to completely stop and

then turn off the mechanical pump

Our completely assembled system is shown in figure 2-27 below

Fig 2-27 Complete System

41

Chapter 3 TENSILE TESTING IN DEPTH

31 Experimentrsquos Purpose and Principles

By means of Universal testing machine and Strain gauges we were able to observe discuss and

analyze the phenomena created when a specimen of certain material is manipulated under an external load

and determine the stress strain and deformation values later we can use the graphing methods of

stress-strain diagram to describe it

The main point of this experiment is that after the tensile specimen is tested use computer analysis

and the actual strain data and after statistical adjustment make the final results report (Tensile testing

experiment is in accordance with ASTM E8)

32 Experimentrsquos Equipment

321 Universal Testing Machine

For the materials testing experiment part of this research we use a Universal Testing Machine as

shown in figure 31 The maximum load it can apply is 100 Ton After the test specimen is secured on the

device with the use of instrumentation the load exerted and the effects of this become apparent on the

specimen and even the smallest of changes can be recorded For our research we used the Chun Yen

Testing Machines Co Ltd 100 Ton Micro Computer Universal Tensile Tester

Fig 31 Universal Testing Machine

42

Table 31 shows the specifications for this machine

Max Capacity 100 Ton

Accuracy plusmn1

Tension (mm) Max Space 1150mm

Grip for Rod 20-70mm

Ram Stroke 250mm

Effective Column Interval 940mm

Crosshead Speed 300mmmin

Testing Speed 0-50mmmin

Volume of Machine 1700times1000times3350mm(LtimesWtimesH)

Volume of Control Panel 1000times800times1500mm(LtimesWtimesH)

Weight 8000kg

Power 3∮220V 20A

Computer AMD K6-2-350

OS Windows XP

Screen 15rdquo CRT

Table 3-1 Chun Yen Testing Machine Specs Table

The connections diagram is shown in figure 3-2

Fig 3-2 Diagram for System Connections

43

When the test specimen is placed when the external force is applied the Load Cell can measure the

size of the applied force and the Encoder measures the expansion rate of change The Local Controller

receives all the information from the 2 units after arranging the results they are displayed in the

computer and they can be afterwards submitted for more complex analysis such as Finite Element

Analysis and we can get the Stress-Strain Diagram

322 Strain Measurement Equipment

The equipment used in our research provides a four-channel measurement that means we can use up

to 4 strain gauges at a time to do our measurements and provides 3 different bridge arrangements as

shown in figure 3-3

(a) (b) (c)

Fig 3-3 Input Connections for Strain Indicator

Figure 3-3 (a) is the Quarter Bridge (b) is the Half Bridge and (c) is the Full Bridge and Transducers

For our study we used the Quarter Bridge and use the Strain Gauge values to decide the position of the

connecting wires The Strain indicator is shown in figure 3-4

Fig 3-4 Vishay Micro-Measurements Model P3 Strain Indicator and Recorder

44

Input Connections Tool Free eccentric lever release

4-channel input

Wire diameter16-28AWG

Bridge Configurations Quarter- Half- and Full Bridge

Bridge Impedance 60-2000Ω

Display 128 64 pixel FSTN positive gray LCD

Data Conversion AD Converter filter

Measurement Range Resolution Strain Range plusmn155mVV

Resolution plusmn00005mVV

Measurement Accuracy plusmn01 of reading plusmn3 counts

Gage Factor Control 0500-9900

Balance Control Software either manual or automatic

Bridge Excitation 15VDC nominal

Communication Interface USB Cable Included

Data Storage Removable Media Card

Shunt Calibration Across bridge completion resistors controlled

by software When Gage Factor=200

120Ω350Ω1000Ω

Analog Output Value 0 to 25V max

Ranges plusmn320 microε plusmn3200 microε plusmn32000 microε

Error 05 output voltage +5mV

Max Error 14 output voltage + 20mV

Update rate 480 samplessec

Output Load 2000Ω

Power Battery Two Alkaline D cells

Battery life 400 hours typ

USB 5V 100mA

Operational Environment Temperature 0-50

Humidity Up to 90 Non-condensing

Case Aluminum Alloy

Size and Weight 228times152times152(mm) 20(kg)

Table 3-2 Vishay Micro-Measurements Model P3 Strain Indicator and Recorder Specs

45

323 Strain Gauge

The strain gaugersquos main basic principle is to use a resistancersquos characteristics to measure the strain

The inside connections of the strain indicator are shown in figure 3-5

Fig 3-5 Inner Connections

As shown above this is a quarter-bridge connection We connect equal-length 3 wires to the 2

connections allowed by the strain gauge wire 1 and 3 can be used to cancel out the effects of temperature

to the resistance and because of the addition of wires 1 and 3 wire 2 can directly measure the experiment

results from the strain gauge and therefore the strain developed with no influence of temperature

If there were no two measuring leads then the relations will be

R 4 =R g +2R L

Where Rg is the Strain Gauge Value and RL is the wire resistance then

4

4

R

R=

Lg

g

RR

R

2

=

gL

gg

RR

RR

21

amp

4

4

R

R=

g

g

R

R(1- L)

Where L is the Signal Loss Factor and so

L =gL

gL

RR

RR

21

2

g

L

R

2R if

g

L

R

2Rltlt1

46

(Actual Value R g =120R L =08g

L

R

2Ris always much smaller than 1)

R 4 =R g +2R LR 2 =R 3 =rR gR 1 =R g 32 RR =0

V 0 =V 2)1( r

r

(

4

4

R

R-

1

1

R

R)

The first term describes loss attenuation effects second term describes loss of balancing capabilities

effects

V 0 =V 2)1( r

r

[

)2

(Lg

g

RR

R

+

T

Lg

g

RR

R

)

2( + T

Lg

L

RR

R

)

2

2( -(

g

g

R

R) T ]

The first term describes loss attenuation effects and loss of balancing capabilities effects the second

third and fourth terms describe the temperature effects on the wire

For the three-wire method we have

L =gL

gL

RR

RR

1

g

L

R

R if

g

L

R

Rltlt1

V 0 =V 2)1( r

r

[

)(Lg

g

RR

R

+

T

Lg

g

RR

R

)( + T

Lg

L

RR

R

)

2( -

T

Lg

g

RR

R

)( - T

Lg

L

RR

R

)

2( ]

V 0 = V2)1( r

r

)(

Lg

g

RR

R

In the last four terms inside parenthesis we can see the effects of temperature being cancelled out and the

effect on first term is not great so this is the reason why in our research we use three wires

47

324 Specimen Measurements

The tensile specimens used in this research are compliant of ASTM E8 Tensile parameters as shown

in figure 3-6

Fig 3-6 Tensile Specimen

Diameter

D(mm)

Gauge

Length

G(mm)

Smallest

Arc

Radius

R(mm)

Shortest

Area

A(mm)

Total

Length

L(mm)

Clamping

Area

Length

B(mm)

Clamping

Area

Diameter

C(mm)

Bar 125 02 625 01 gt10 gt75 ~ 145 ~ 35 20

Table 3-3 Specifications for Round Bar

33 Experiment Procedure

1 Attaching the Strain Gauge to the Tensile Specimen

(1) Prepare 1 ASTM E8 compliant tensile specimen round bar as shown in figure 3-7

(2) Prepare Strain Gauge as those described in table 3-4

(3) Prepare other consumables and adhesive agent such as epoxy adhesive or

cyanoacrylate adhesive as shown in figure 3-8

48

Fig 3-7 Actual Tensile Specimen

Fig 3-8 Other Materials Used (Such as Alcohol gauze transparent tape adhesive)

Gage Type

EA-06-120LZ-120E

Resistance in ohms at 24∘C

1200plusmn03

Gage Factor at 24∘C

2075plusmn05

Transverse Sensitivity at 24∘C

(+07plusmn02)

Table 3-4 Specifications for Strain Gauge

2 Attaching Strain Gauge

As shown in following figures we shall explain the attachment of the strain gauge

(1) Use sand paper and a rasp to clean thoroughly the surface where the strain gauge will be

attached to

49

(a)

(2) Use alcohol to wash the surface where the strain gauge will be attached and use gauze to rub

it off

(b)

(3) Find a clean surface and clean it with alcohol and gauze

(c)

(4) Place the strain gauge in the clean surface Use a piece of transparent tape on top of the strain

gauge after securely placed rip it off the surface carefully

50

(d)

(5) Use a piece of white paper to mark the place where the strain gauge will be attached and in

this way we can make sure that the strain gauge will be placed as horizontally and vertically

correct as possible

(e)

(6) In the place where we had our mark place the strain gauge

(f)

(7) Carefully lift one side of the tape and apply some of the adhesive agent to both the strain

gauge and specimenrsquos surface

(g)

51

(8) We need to make sure that the gauge and the specimen will be firmly attached so we gently

apply pressure with our thumb

(h)

(9) After the adhesive is fully dry we can carefully rip off the tape

(i)

(10) We need to do the whole process twice one for the horizontally placed strain gauge and one

for the vertically placed strain gauge

52

(j)

(11) We now proceed to solder the wires to the strain gauge

(k)

(12) After soldering we use a Volt Multimeter to measure that there is no contact between wires

If there is none then the specimen is ready for testing

(l)

(13) We now need to measure a 5cm distance and mark it to check and compare the elongation

before and after the tensile testing

(m)

53

Fig 3-9 Specimen-Strain Gauge Process

3 Tensile Test

(1) Enter the computer application that controls the tensile testing machine

(2) Turn on the tensile testing machine main switch

(3) Adjust the hydraulic pump to go back to its original position

(4) Bring the lowering motor down to a distance enough so as to attach the tensile specimen to the

system open the clamps and secure the specimen

(a)

(5) Connect all the necessary wires to the strain indicator equipment

54

(b)

(6) Start the ascending motor and wait for the expansion

(c)

Fig 3-10 Specimen-Tensile Testing Process

4 Start the Test

(1) Enter the software application and enter some variables needed for the experiment in the

specific screen

(2) Go back to the main screen and press the [測試] (measure) button to start the test and auto

recording in the software

(3) After the specimen breaks the mechanical device will automatically stop and ask the user to

enter the total displacement We take out the specimen from the testing machine and adjust the

machinersquos position back to its original position

(4) Save the results information

(5) Record the results from the strain indicator

34 Results

From this experiment we can get the Poissonrsquos Ratio Youngrsquos Modulus and Yield Strength etc and

because of the slippage phenomenon in the clamp at the moment of the test then the Elastic Limit will

display some yield phenomena So omit any undesirable results we just take the Yield portion of the

results as reference

In the process of the experiment the most important part to attend to is the attaching of the strain

gauge because the gaugersquos purpose is to measure the strain developed during the test and this strain

might be very small If the gaugersquos angle change during the test ie is not well attached this will affect

the accuracy of the measurements of Poissonrsquos ratio and Youngrsquos modulus

55

The materials provided by the manufacturer are SUM 23 and SUM 43 steel round bars and these two

types of materials have been through different heat treatment processes so they can be sub-divided

further into untreated material heat-treated material and black surface heat treated material for the two

materials with heat treatment the treatment process and finished are different In the end we only have

the mechanical properties that were calculated after our research of these materials

All of the specifications are identical to those shown in figure 3-6

341 SUM 23

Fig 3-11 SUM 23 Untreated Material

Number 7 10

Hardness(HRB) 74 75

Yield Stress (MPa) 448 440

Tensile Strength (MPa) 544 560

Poissonrsquos Ratio 029 027

Youngrsquos Modulus (GPa) 203 210

Cut-off Area Shrinking () 42 41

Elongation () 1125 1011

Table 3-5 Mechanical Properties of SUM 23 Untreated

56

Stress-Strain Diagram

(a)

(b)

57

Fig 3-12 Stress-Strain Diagrams for (a) 7 Round Bar and (b) 10 Round Bar

Cut-Off Area

(a)

(b)

Fig 3-13 Cut-Off Area of (a) 7 Round Bar and (b) 10 Round Bar

58

SUM 23 Nickel Round Bar

Fig 3-14 SUM 23 Nickel Material

Number 1 2 3 4

Hardness(HRB) 48 50 49 48

Yield Stress (MPa) 370 370 380 400

Tensile Strength (MPa) 455 451 450 450

Poissonrsquos Ratio 028 046 029 026

Youngrsquos Modulus (GPa) 243 303 246 206

Cut-off Area Shrinking () 803 803 726 601

Elongation () 566 65 602 647

Table 3-6 Mechanical Properties of SUM 23 Nickel

59

Stress-Strain Diagram

(a)

60

(b)

(c)

(d)

61

Fig 3-15 Stress-Strain Diagrams for (a) 1 Round Bar (b) 2 Round Bar (c) 3 Round Bar and (d)

4 Round Bar

Cut-Off Area

(a)

(b)

62

(c)

(d)

Fig 3-16 Cut-Off Area of (a) 1 Round Bar (b) 2 Round Bar (c) 3 Round Bar and (d) 4 Round

Bar

63

SUM 23 Black Surface Round Bar

Fig 3-17 SUM 23 Black Surface Material

Number 1 2 3

Hardness(HRB) 51 50 51

Yield Stress (MPa) 378 371 369

Tensile Strength (MPa) 467 465 464

Poissonrsquos Ratio 03 016 04

Youngrsquos Modulus (GPa) 215 266 266

Cut-off Area Shrinking () 986 94 848

Elongation () 748 805 761

Table 3-7 Mechanical Properties of SUM 23 Black Surface Material

64

Stress-Strain Diagram

(a)

(b)

65

(c)

Fig 3-18 Stress-Strain Diagrams for (a) 1 Round Bar 2 Round Bar and (c) 3 Round Bar

Cut-Off Surface

(a)

66

(b)

(c)

Fig 3-19 Cut-Off Surface of (a) 1 Round Bar 2 Round Bar and (c) 3 Round Bar

67

342 SUM 43

Fig 3-20 Untreated SUM 43 Untreated Material

Number 1 5

Hardness(HRB) 76 75

Yield Stress (MPa) 572 594

Tensile Strength (MPa) 743 785

Poissonrsquos Ratio 027 029

Youngrsquos Modulus (GPa) 200 202

Cut-off Area Shrinking () 338 2944

Elongation () 857 894

Table 3-8 Mechanical Properties of SUM 43 Untreated

68

Stress-Strain Diagrams

(a)

(b)

Fig 3-21 Stress-Strain Diagrams for SUM 43 (a) 1 Round Bar and (b) 5 Round Bar

69

Cut-Off Area

(a)

(b)

Fig 3-22 Cut-Off Area of SUM 43 (a) 1 Round Bar and (b) 5 Round Bar

70

SUM 43 Nickel Round Bar

Fig 3-23 SUM 43 Nickel Material

Number 4 5

Hardness(HRB) 51 50

Yield Stress (MPa) 1580 1544

Tensile Strength (MPa) 1639 1625

Poissonrsquos Ratio 03 028

Youngrsquos Modulus (GPa) 194 201

Cut-off Area Shrinking () 1697 137

Elongation () 376 265

Table 3-9 Mechanical Properties of SUM 43 Nickel

71

Stress-Strain Diagrams

(a)

(b)

Fig 3-24 Stress-Strain Diagrams for (a) 4 Round Bar and (b) 5 Round Bar

72

Cut-Off Area

(a)

(b)

Fig 3-25 Cut-Off Area of (a) 4 Round Bar and (b) 5 Round Bar

73

SUM 43 Black Surface Material

Fig 3-26 SUM 43 Black Surface Material

Number 3 5

Hardness(HRB) 56 56

Yield Stress (MPa) 1416 1361

Tensile Strength (MPa) 1591 1402

Poissonrsquos Ratio 029 031

Youngrsquos Modulus (GPa) 200 202

Cut-off Area Shrinking () 139 124

Elongation () 24 24

Table 3-10 Mechanical Properties of SUM 43 Black Surface Material

74

Stress-Strain Diagrams

0 2 4 6 8 10 12 14

-200

0

200

400

600

800

1000

1200

1400

1600

1800

應力 (MPa)

應變()

(a)

0 2 4 6 8 10

-200

0

200

400

600

800

1000

1200

1400

1600

應力

(MPa)

位移 ()

(b)

Fig 3-27 Stress-Strain Diagrams for (a) 3 Round Bar and (b) 5 Round Bar

(Note These curves were formulated using Visual Solutions Inc VisSim Software)

75

Cut-Off Area

(a)

(b)

Fig 3-28 Cut-Off Area of (a) 3 Round Bar and (b) 5 Round Bar

76

The force value (N) was retrieved from the Universal Testing Machine

The Poissonrsquos Ratio (ε) is calculated as

ε =

the values for the Poissonrsquos Ratio are in average around 0297

The Youngrsquos Modulus (E) is calculated as

E =

Where

Stress =

Cross-sectional Area =

where D is the Diameter

The value for D was in average around 1258 mm

The values shown by the computer because there is Slippage phenomena between the Clamp and the

specimen will not be taken into consideration for the elongation strain and Youngrsquos modulus and we will

refer to the values that we have meticulously calculated

77

Chapter 4 AR COATING IN DEPTH

41 Experimentrsquos Purpose and Principles

By means of a vacuum chamber and several other instruments we intend to apply Anti-Reflective

Coating using deposition process to a laser diode and in this way reduce its refraction so as to make it

lose less light in the process of amplification and we can control certain wavelengths we want produced

for certain desired applications in our case we are attempting to re-create a Bose-Einstein Condensate

An optimal BEC apparatus is shown in figure 4-1

Fig 4-1 BEC Apparatus

The main point of this experiment is to build a vacuum chamber system attach all the instrumentation

needed (Vacuum pump deposition meter and voltmeter) and use it to apply AR coating to a laser diode

After we have accomplished the AR coating other team will be in charge of designing the BEC apparatus

and use the results of our research

78

42 Experimentrsquos Equipment

421 Vacuum Chamber

For this research we designed a vacuum chamber whose main body is shown in figure 4-2 Its

dimensions are

Width 240 mm

Length 240 mm

Height 200 mm

Outer Diameter 4 in

Inner Diameter 15 in

Fig 4-2 Vacuum Chamber Main Body

The chamber is made up of 6 pass ways pass way A is the connection with the Laser Deposition

Equipment pass way B is the connection with the Turbo Pump and pass way C is for the connection with

the Deposition Source

A

C

B

79

Pass way C is for the deposition source as mentioned above This is a system where a thermal

resistance is heated by passing a high current through it which heats up a filament boat (made of tungsten)

where the material to be evaporated is place We control the temperature as such that the material will

evaporate and the heat will not cause the filament boat to crack

Because P = Isup2 R (where P is power I is current and R is resistance) to avoid the current to flow

where it is not desired we decided that the material for the Thermocouple shown in figure 4-3 should be

Copper ᴓ 63 mm We choose it that way because Copper has very good heat dissipation characteristics

and the resistance value is low It can reduce the value of the current enough to make the thermocouple to

create heat

Fig 4-3 Thermocouple

To the thermocouple we attach the tungsten filament boat We need to take notice of materials to be

used in this design because when using high current the tungsten filament boar will heat up and so the

material must be able to keep up with the heating potential of tungsten and has a low coefficient of heat

dissipation to avoid the tungsten to fail when heating up and therefore not evaporating Considering all

this we decide to use Stainless Steel

Because this clamp will be assembled inside the chamber after many revisions it was determined it

will have the shape shown in figure 4-4

Fig 4-4 Filament Boat Clamp Design

80

For the tungsten filament boat we bought the product from a distributor The dimensions are

Length 100 mm

Width 10 mm

Height 1 mm

Our thermocouple is 15 in but the pass way C is 4 in so we need to attach a Flange that connects

15in to 4in Because these specifications are quite difficult to achieve by Milling we had to use

electrical wire cutting

For the laser clamping system where the laser that is going to be AR coated will be placed will be

connected to pass way A the assembly is shown in figure 4-5 below

Fig 4-5 Cover Assembly

For this design we used an O-ring instead of a gasket so as to save time The design of the assembly

where the laser will be placed is shown in figure 4-6

Fig 4-6 Upper Cover Inner Assembly

D

E

F

81

Point D is the plate in the assembly where the laser diode will be fixed Because of the easy

processing we decide to use Aluminum and it is screwed to the top cover Point E is the connection for

the Quartz crystal resonator and it is designed in the same as point F in this way the results of the quartz

microbalance system will be more accurate in real time Point F is the final resting place for the laser

diode We use a Thor Labs Base with dimensions of ᴓ 9mm and ᴓ 56mm for two different size laser

diodes It just needs to be plugged in for easy installation

From figure 4-6 we know that the system needs signal system connections and because of the

change in temperature inside the chamber this could affect the functioning of the quartz microbalance so

we also need to install water tubes for cooling This is shown in figure 4-7 below

Fig 4-7 Diagram of Upper Cover Connections

In figure 4-8 we show the Feed through connections and their functions

Fig 4-8 Feed through Diagram

82

1 SQM-160 wire 5 Laser Connection 1 (Vin)

2 SQM-160 (G) 6 Laser Connection 2 (G)

3 K-Type-1 7 Laser Connection 3 (PD)

4 K-Type-2 8 Not In Use

The fully assembled chamber is shown in figure 4-9

Fig 4-9 Fully Assembled Chamber

422 Quartz Crystal Microbalance

For measuring the deposition on our target for coating we used the Inficon SQM-160 RateThickness

Monitor It is an easy to use instrument for measuring many types of thin-film coatings as shown in

figure 4-10

(a) Front Panel (b) Back Panel

Fig 4-10 Inficon SQM-160

83

Table 4-1 shows the technical specifications for this equipment

Number of sensors 2 Standard 4 additional optional

Sensor Frequency Range 40 MHz ~ 60 MHz

Reference Frequency Accuracy 002

Thickness Display Resolution 1 Aring

Thickness Resolution 015 Aring (Std) 0037 Aring (Hi Res)

Density of Stored Films 05-9999 gmcc

Tooling 10-399

Z-Factor 010-1000

Final Thickness 0000-9999k Aring

Measurement Period 15 to 2 sec

Simulation Mode Yes

Frequency Mode Yes

Rate Resolution 011 Arings

Dual Crystal Yes

Etch Mode Yes

Crystal Tooling 10-399

Crystal Fail Min Max 40 to 60 MHz 41 to 61 MHz

Power 100-120 200-240~plusmn10 nominal 20W

Operation Environment 0degC ~ 50degC

0 ~ 80 RH non-condensing

0 ~ 2000 meters

Class 1 Equipment

Pollution Degree 2

Rack Dimensions 885mm x 2127mm x 1969mm

Weight 27 kg

Table 4-1 Inficon SQM-160 RateThickness Monitor Specs

84

To the SQM-160 we need to connect an Oscillator We use the Sigma Instruments Remote Oscillator

Ser No 2 268 as shown in figure 4-11

Fig 4-11 Sigma Instruments Remote Oscillator

The connections diagram is shown in figure 4-12

Fig 4-12 SQM-160 Connections Diagram

85

423 Turbo Pump

For our experiments we used the Pfeiffer TCP 015 Electronic Drive Unit shown below in figure 4-13

Table 4-2 shows the technical specifications for this equipment

(a) Front Panel (b) Back Panel

Fig 4-13 Pfeiffer TCP 015 Electronic Drive

Connection Voltage (100V) 90-112

Mains Frequency 5060 Hz

Start-up Current 22 A

Nominal Frequency 1500 Hz

Rotation Speed 10V = 1500Hz plusmn2

Analog Output Current 10 V = 25 A plusmn 5

Rotation Speed Switchpoint 750 Hz

Works Setting 8 min

Permissible Ambient Temperature 0degC ~ 40degC

Dimensions Front Panel 1285mm x 1063mm

Insertion Length 227mm

Weight 27 Kg

Table 4-2 Pfeiffer TCP 015 Electronic Drive Specs

86

The connections diagram is shown in figure 4-14

Fig 4-14Connections Diagram for Pfeiffer TCP 015

To measure the pressure inside the chamber we use the Granville Phillips 375 Convectron Vacuum

Pressure Controller shown in figure 4-15

(a) Front Panel (b) Back Panel

Fig 4-15 Granville Phillips 375 Convectron

87

Its dimensions are shown in figure 4-16

Fig 4-16 Dimensions of Convectron

Table 4-3 shows the technical specifications for this equipment

Table 4-3 Granville Phillips 375 Convectron Vacuum Pressure Controller Specs

88

424 Multimeter

For our experiment we used the Keithley 2000 Digital Multimeter as shown in figure 4-17

(a) Front Panel (b) Back Panel

Fig 4-17 Keithley Model 2000 6-12-Digit Digital Multimeter

Its technical specifications are shown in table 4-4

Table 4-4 Keithley Model 2000 6-12-Digit Digital Multimeter Specs

89

43 Experiment Procedure

1 Connecting together the equipment and the chamber

(1) We first connect the resonator to the thickness monitor and connect the other side to the

chamber

(2) We now connect the flexible tubes to the turbo pump on one side and to the chamber on the

other

(3) We need to check that tubes are tightly connected to avoid any leaks in the vacuum pumping

process which will not allow us to get to our goal of Torr As shown in figure 4-18

(4) Connect the convectron to the system as shown in figure 4-19

Fig 4-18 checking for leaks using alcohol

Fig 4-19 Convectron attached to System

90

(5) Attach the clamps of the Multimeter to the bottom of the chamber as shown in figure 4-20

(6) Place the Quartz crystal in place

(7) Close tight vacuum chamber

(8) Connect all electrical appliances to power source

Fig 4-20 Multimeter Connections

2 Starting up the System

(1) We turn on all the devices as such Check all systems are ready to function Reset all values

that might be left over from previous tests

(2) Start the thickness monitor and set all values for this experiment In our case we got to testing

the system but not actual coating So we used the simulation mode of the thickness monitor as

shown in figure 4-21

Fig 4-21 Simulation Mode

91

(3) Start the turbo pump Make sure the lid on the vacuum chamber is tightly closed

(4) Start convectron and record initial pressure

(5) Start Multimeter and record initial current

3 Coating Process

(1) If we have the deposition material inside the filament boat the power source for the high

current must be started as well

(2) Record all initial values for thickness current pressure

(3) For an ideal experiment we need a thickness of around 101 nm a pressure of Torr and

a current of 300 A

44 Results

From previous experiments we have shown that we can turn a LED into a laser by means of AR

Coating In figure 4-22 shown below we can compare the actual results of a Diode before and after AR

coating From the blue line we can see that when the diode is at a current of 15mA its light will change

from LED to laser and if we look at the red line its critical current is around 30 to 35 mA

Fig 4-22 AR Coating Comparison for Laser Diodes

This means that the light emitted is not as strong as if the diode had been coated because inside the

chamber there must be some excitation first so the reflectivity of both sides inside the diode must be high

So because of the coating in one of the sides we have opened a door and let the light come out so the

critical current is risen as such and will be higher value than that of before the coating

92

In the following figures we can see the difference between before and after coating in a material The

thickness is around 1016 nm for this material

Fig 4-23 Before Coating

Fig 4-24 After Coating

93

Chapter 5 CONCLUSIONS AND RECOMMENDATIONS

51 Conclusions

For the first part of this independent study taking into consideration the data that came out of our

research and that sent by the provider we can say

1 SUM 23 after heat treatment will unexpectedly develop cracking in the middle of the tensile

testing process and suddenly break

2 Itrsquos possible that in the process of heat treatment to the SUM 23 material the treatment was not

uniform and this will create a pre-loaded moment force on one side that pushes on the other side

of the specimen resulting in material deformation

3 In the process of attaching the strain gauges to the materials it is very easy to make errors due to

poor adhesion or sudden removal in the tensile testing process

For our second part of the independent study the following can be made

1 At the beginning of this independent study we had no idea what Bose-Einstein Condensate was

or what was its purpose After much literature we finally comprehended the basic principles to

put into practice for our research

2 Our systemrsquos basic working principles and equipmentrsquos complexity are a little difficult to grasp

but hopefully we were able to understand enough of it

3 Theoretically from relation between the power and current we can know the advantages and

disadvantages of AR Coating

4 We were able to assemble the system and run test on its functions Even though we were able to

do this there is still much more work left to do with this system

52 Recommendations

For the Tensile Testing the following can be said

1 Ask the provider to check on the process of heat treatment on the SUM 23 material and give

them the information we have gathered through our test so they can correct for the mechanical

properties found if any change is needed

2 To avoid the problem of the inaccuracy of the poor adhesion of strain gauges we can attach

multiple strain gauges to the same one specimen so as to correlate data and improve our results

For the AR Coating the following can be said

1 We need to make sure that there are no physical defects on the main body of the chamber so as to

achieve maximum efficiency in the vacuum process If there was then the vacuum will arrive to

certain point and then start to decrease

2 It would be preferable to add some sort of visual aid that will allow the user to check the inside of

the chamber without actually opening it This will help us determine at what times we should

manipulate the current to better evaporate the substrate

94

REFERENCES

[1] A L Window Strain Gauge Technology Elsevier Applied Science London and New York 2nd

Edition 1992

[2] CC Perry and HR Lissner Strain Gauge Primer McGraw-Hill Book Co Inc New York 1955

[3] James W Dally William F Riley McGraw-Hill 1978

[4] University of Colorado Boulder BEC - What is it and where did the idea come from

httpwwwcoloradoeduphysics2000becwhat_is_ithtml

[5] Ultraslow Light amp Bose-Einstein Condensates Two-way Control with Coherent Light amp Atom

Fields Harvard Hau Lab Dr Lene Vestergaard Hau Optics amp Photonics News 16 1995

[6] The Art of Taming Light Ultra-slow and Stopped Light Harvard Hau Lab Dr Lene

Vestergaard Hau Europhysics News 2004

[7] Nonlinear Optics Shocking Superfluids Harvard Hau Lab Dr Lene Vestergaard Hau Nature

Physics 2007

[8] Model P3 Strain Indicator and Recorder Instruction Manual Vishay Micro-Measurements 2005

[9] Granville-Phillips Series 375 Convectron Vacuum Gauge Controller Instruction Manual Brooks

Automation 2008

[10] Effect of Film Thickness on the Validity of the Sauerbrey Equation for Hydrated Polyelectrolyte

Films Vogt Lin Wu White 2004

[11] Quartz Crystal Microbalance Study of DNA Immobilization and Hybridization for DNA Sensor

Development Chang Zhao 2008

[12] Installation of Strain Gages with SR-4 PrecoatAdhesive Vishay Micro-Measurements 2005

[13] Strain Gauge Measurement ndash A Tutorial National Instruments 1998

[14] Correlation between Vickers Hardness Number and Yield Stress of Cold-Formed Products

Yavuz Tekkaya

[15] httpsenwikipediaorg

Page 9: PC Hinge Materials Testing and AR Laser Diode Coating

9

Fig 3-11 SUM 23 Untreated Materialhelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 55

Fig 3-12 Stress-Strain Diagrams for 7 and 10 Round Barhelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 56

Fig 3-13 Cut-Off Area of 7 and 10 Round Barhelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 57

Fig 3-14 SUM 23 Nickel Materialhelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 58

Fig 3-15 Stress-Strain Diagrams for 1 2 3 and 4 Round Barhelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip60

Fig 3-16 Cut-Off Area of 1 2 3 and 4 Round Barhelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 62

Fig 3-17 SUM 23 Black Surface Materialhelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 63

Fig 3-18 Stress-Strain Diagrams for 1 2 and 3 Round Barhelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 65

Fig 3-19 Cut-Off Area of 1 2 and 3 Round Barhelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 66

Fig 3-20 SUM 43 Untreated Materialhelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip67

Fig 3-21 Stress-Strain Diagrams for 1 and 5 Round Barhelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 68

Fig 3-22 Cut-Off Area of 1 and 5 Round Barhelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 69

Fig 3-23 SUM 43 Nickel Materialhelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 70

Fig 3-24 Stress-Strain Diagrams for 4 and 5 Round Barhelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 71

Fig 3-25 Cut-Off Area of 4 and 5 Round Barhelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 72

Fig 3-26 SUM 43 Black Surface Materialhelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 73

Fig 3-27 Stress-Strain Diagrams for 3 and 5 Round Barhelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 74

Fig 3-28 Cut-Off Area of 3 and 5 Round Barhelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 75

Fig 4-1 BEC Apparatushelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 77

Fig 4-2 Vacuum Chamber Main Bodyhelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 78

Fig 4-3 Thermocouplehelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip79

Fig 4-4 Filament Boat Clamp Designhelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 79

Fig 4-5 Cover Assemblyhelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 80

Fig 4-6 Upper Cover Inner Assemblyhelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 80

Fig 4-7 Diagram of Upper Cover Connectionshelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 81

Fig 4-8 Feed Through Diagramhelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 81

Fig 4-9 Fully Assembled Chamberhelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 82

Fig 4-10 Inficon SQM-160helliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 82

Fig 4-11 Sigma Instruments Remote Oscillatorhelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 84

Fig 4-12 SQM-160 Connections Diagramhelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 84

Fig 4-13 Pfeiffer TCP 015 Electronic Drivehelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 85

Fig 4-14 Connections Diagram for Pfeiffer TCP 015helliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 86

Fig 4-15 Granville Phillips 375 Convectronhelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 86

Fig 4-16 Dimensions of Convectronhelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 87

Fig 4-17 Keithley Model 2000 6-12-Digit Digital Multimeterhelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 88

Fig 4-18 Checking for Leaks Using Alcoholhelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 89

Fig 4-19 Convectron Attached to Systemhelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 89

Fig 4-20 Multimeter Connectionshelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 90

Fig 4-21 Simulation Modehelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 90

Fig 4-22 AR Coating Comparison for Laser Diodeshelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 91

Fig 4-23 Before AR Coatinghelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 92

Fig 4-24 After AR Coatinghelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip 92

10

Chapter 1 INTRODUCTION

11 Motivation and Background

In response that new generation computers are gradually reducing their size the diameter of

the structures of the hinges used by NB computers must also follow but the hinge strength may

also become smaller due to the reduction of diameter and result in the phenomenon of

insufficient strength In addition the disk-type spring that is source of the torque may also be

insufficient due to the narrowing of the structure Therefore it is necessary to direct a structural

analysis of the hinge for the existing laptops so that we can identify the stress concentration

point The stress concentration point is usually the point where material damage behavior is

encountered the easiest and if we can find the point where breaking occurs most often we can

improve the design of the existing structure to enhance the strength of the hinge structure

Second the structure of the hinge is too complicated the traditional mechanics of materials

analysis methods and formulas are no longer suitable for analysis of a wide arrange of hinge

design In recent years finite element analysis methods have been widely applied in various

fields such as electronics machinery aviation and so on

Therefore to meet the need of the industry and with the purpose of reducing design time

how to design a notebook computer hinge without compromising mechanical stability and

materialrsquos hardness which will operate equally under equal conditions In other words be able to

meet the needs of the size decreasing NB computers market as the needs for this kind of

accessories will increase in the near future If we take into consideration the traditional ways of

design we seek to reduce the costs of use of machinery and molding by applying Finite Element

Analysis methods to our study and also increase the flexibility of designing methods

The second project was brought in by Prof Chuang and it is to help in the further research of

the Bose-Einstein condensate This is a state of matter of a dilute gas weakly interacting bosons

(subatomic particles that obey the Bose-Einstein statistics) confined in an external potential and

cooled down to temperatures very near absolute zero (0 K or -27315deg C) Under these conditions

a large number of bosons occupy the lowest quantum state of the external potential at which

point quantum effects become apparent at macroscopic scale This state of matter was predicted

by Satyendra Nath Bose and Albert Einstein in 1924~1925 Then 70 years later the 1st gaseous

condensate was produced by Eric Cornell and Carl Wieman in 1995 at the University of

Colorado (Boulder) NIST-JILA lab and because of this along with Wolfgang Ketterle of MIT

they received the 2001 Nobel Prize in Physics

11

We wish to investigate the properties of Anti Reflecting Coating on laser diodes Hopefully

we will be able to achieve the desired effect of reducing the surface reflection coefficient and

find applications for it

12 Research Objective

We wish to analyze the normal composition of the notebook computerrsquos hinge at which

point in the assembly is clearly the weakest and at this time in the assembly the strength and

durability are influenced The main point is to see if we can affect the normal operation and work

life

The objective of this thesis is to present the results of the material properties under tensile

testing find the mechanical properties and after using finite element analysis determine what

material is the best for our purposes

Fig 1-1 Notebook Computer Hinge

For our second research we wish to produce and analyze laser diodes with anti-reflective

coating and test its properties and applications

When semi-conductor laser has been submitted to current it will produce resonance inside it

and light will be stimulated to come out Please refer to figure 1-2 for the basic structure of a

laser

Fig 1-2 Basic Structure of a Laser

1 Gain Medium

2 Laser Pumping Energy

3 High Reflector

4 Output Coupler

5 Laser Beam

12

But when the laser diode generates light but the laser diode canrsquot produce light on itself it

must wait for the current to be higher than certain value which is called the critical current Until

the light goes over this threshold then it is considered laser light if not it is just considered as a

common LED light source Please refer to figure 1-3

Fig 1-3 Comparison between LED and Laser Diode

As we can see from figure 1-3 all of the light that goes over the critical current is laser light

and so the external cavity semi-conductor laser that we built needs Anti-Reflective Coating

because the method we want to use needs an external cavity laser that has been covered with AR

Coating and a Diffraction Grating We use this configuration first by shooting the laser to the

grating and this will be shot back to the laser creating the external resonance cavity which is

shown in figure 1-4

Fig 1-4 External Cavity Design

13

Two configurations are shown the Littrow Configuration and the Littman-Metcalf

Configuration The Littrow configuration contains a collimating lens and a diffraction grating as

the end mirror The first order diffracted beam provides optical feedback to the laser diode which

has AR Coating The emission wavelength can be turned by rotating the diffraction grating A

disadvantage is that it also changes the direction of the output beam

In the Littman-Metcalf configuration the grating orientation is fixed and an additional mirror

is used to reflect the first order beam back to the laser diode The wavelength can be turned by

rotating that mirror This configuration offers a fixed direction of the output beam and also tends

to exhibit smaller line width as the wavelength selectivity is stronger A disadvantage is that

zero order reflection of the beam reflected by the tuning mirror is lost so that the output power is

less than that of a Littrow laser

13 Methodology

The aim of this research is to find the mechanical properties of materials after being

subjected to tensile testing through finite element analysis observations and determine what

material is best for our purposes taking into consideration the strength and durability of the

material among other properties to find use and applications for the AR coated laser diodes to

further improve the grasp of the Bose-Einstein condensation working principles

14 Organization of the Thesis

The research paper includes five chapters

1 Chapter 1 explains the motivation background objective and methodology of this study

2 Chapter 2 explains the working principles and basic knowledge needed to understand this

study

3 Chapter 3 explains the tensile testing in detail steps methods and results

4 Chapter 4 explains the AR coating in detail steps methods and results

5 Chapter 5 is the conclusions taken from the results shown in chapter 3 and 4 and

recommendations done after arranging and critical thinking

14

Chapter 2 BASICS THEORIES

21 Tensile Testing

After a specimen is tested with the use of tensile testing we can get the Stress-Strain Curve using the

relation between tension and displacement Typical curves are shown in Fig 2-1

(a) Ductile materials (b) Brittle materials

Fig 2-1 Stress-Strain Curve

The curve is unique for each material and is found by recording the amount of deformation at distinct

intervals of tensile or compressive loads Thanks to the use of the Stress-Strain curve we can get very

useful information such as

211 Youngrsquos Modulus (E)

As shown in Fig 2-1 as long as the external load is not greater than the Proportional Limit the Stress

(σ) and Strain (ε) remain as a linear relation fulfilling Hookersquos Law

σ = Eε

The slope is the constant factor the inverse of the modulus of elasticity E also called Youngrsquos

modulus When the external load goes over the proportional limit the stress-strain relationship doesnrsquot

follow the linear relation anymore but the deformation remains flexible When the load is released the

deformation is completely eliminated and the specimen goes back to its original state This is called

15

Elastic Deformation When the external load goes over the Elastic limit only then does the specimen

presents Plastic Deformation This type of deformation which is irreversible even when the load is

removed comes after the material does under elastic deformation so this means the object will first come

part way to its original shape Common metals and ceramics have roughly the same elastic limits

212 Yield Strength and Yield Point

Some materials display very evident yield phenomena while some materials donrsquot as shown in Fig

2-2 After we exceed the elastic limit if we continue to exert load when we arrive to a certain value

which differs under different materials and external conditions there is sudden decrease in stress and this

is called the Yield Strength and can be defined as the stress at which a material begins to deform

plastically using the equation

σyield =

Where P is the tension force and Ao is the original cut-off area

The stress remain at a certain value after the decrease but the strain increases this phenomena can be

easily appreciated when studying the behavior of common Carbon Steel Fig2-2 (a) but most metals (like

Aluminum Copper or High Steel Carbon) donrsquot display this kind of behavior as shown in Fig 2-2 (b)

Arriving to this point is very difficult and the most commonly used method for this is to add a 02 or

0002 offset yield strength to the curve This point is held constant on the strain axis of the curve and

from the 0002 position we draw a straight line parallel to the linear relationship line the point at where

this line and the stress-strain curve intercept is the point we take as the 02 offset yield strength

(a)Evident (b) Non-evident

Fig2-2 Stress-Strain Curve Comparison on Metals

16

213 Ultimate Tensile Strength and Breaking Strength

After materials undergo yield they keep lending strength and hardening phenomena occurs (work

hardening) on the material and the external load increases When it has reached the highest point this is

called the Ultimate Tensile Strength (UTS) as shown in Fig2-1 The UTS is defined as

σUTS =

Where Pmax is the load at the materialrsquos ultimate tensile strength point and Ao is the original cut-off

area For brittle materials the ultimate tensile strength is the most important mechanical property for

ductile materials the ultimate tensile strength is not commonly used for industrial and designing purposes

because upon arriving to this value the material already has forgone great plastic deformation After the

specimen goes through UTS there will be necking phenomena which is a mode of tensile deformation

where relatively large amounts of strain localize disproportionately in a small region of the material It

results from instability during tensile deformation when a materialrsquos cross-sectional area decreases by a

greater proportion than the material strain hardens The specimen continues to elongate until it finally

breaks and the load at this point is called Breaking Strength The breaking strength is defined as the

greatest stress in tension that a material is capable of withstanding without rupture

Where Pf is the load at the materialrsquos breaking strength point and Ao is the original cut-off area

214 Poissonrsquos Ratio (ν)

For elastic deformation when materials are compressed in one direction they tend to expand in the

other two directions perpendicular to the direction of compression This is called the Poissonrsquos Effect

The Poison Ratio is a measure of the Poissonrsquos effect It is the ratio of the fraction of expansion divided

by the fraction of compression for small values of these changes

ν=-

215 Strain Gauge Basic Principles

The strain gauge is a device used to measure the strain of an object Itrsquos an elongated metal resistor

which is attached to the specimen being measured and when the specimen is under strain and starts to

deform the strain gauge will have a change in the resistance With the change in value we can calculate

the elementrsquos strain or elastic modulus and the Poissonrsquos ratio

It takes advantage of the physical property of electrical conductance and its dependence on the

conductorrsquos geometry When the electrical conductor (the specimen being tested) is stretched within the

limits of elasticity such that it does not break or deform plastically it will become narrower and longer

17

which increases the electrical resistance through-out From the measured resistance of the strain gauge

the amount of stress may be inferred by using the relations

R=

Where R is the original resistance value is the electrical resistivity lo is the original length of the

conductor and Ao is the original cross sectional area of the conductor If after the application of tension

the change in length is Δl let the length of the specimen be l = l + Δlo and the tension is the same

through-out So

And the resistance is

The Gauge Factor is the ratio of relative change in electrical resistance to the mechanical strain in

other words it is the relative change in length It is defined as

The strain gauge was invented in 1938 by Edward E Simmons and Arthur C Ruge and the most

common type consists of an insulating flexible backing which supports a metallic foil usually made of a

brass-nickel alloy It is attached to the specimen by a suitable adhesive As the object is deformed the foil

also deforms and this causes the electrical resistance to change Then this is usually measured using a

Wheatstone bridge shown below and is related to the strain by the Gauge Factor

Fig2-3 Basic Structure of Strain Gauge

18

Fig 2-4 Strain gauge attached to Wheatstone bridge

22 Hardness Testing Basic Principles

221 Brinell Scale BHN

The Brinell Scale characterizes the indentation hardness of materials through the scale of penetration

of an indenter loaded on a material specimen The typical test uses a 10mm diameter steel ball as indenter

(usually of value equal to BHN450) with a 29kN force For softer materials smaller force is used The

indentation is measured and BHN is calculated using the relation

BHN =

radic

Where F is the applied force usually within the range of 100 250 500 750 1000 1500 2000 2500

and 3000 kgf D is the diameter of indenter usually within the range of 5mm or 10mm plusmn0005 margin

and d is the diameter of indentation usually around 2mm Its units are of Kgmmsup2 but are not normally

written

First proposed by Swedish engineer Johan August Brinell in 1900 it was the first widely used and

standardized hardness test in engineering and metallurgy although the large size of indentation and

possible damage to specimen limits its usefulness

Fig 2-5 Brinell Indentation Fig2-6 Brinell Hardness Tester

19

222 Rockwell Scale HR

The Rockwell scale is a hardness scale based on the indentation hardness of a material The Rockwell

test determines the hardness by measuring the depth of penetration of an indenter under a large load

compared to the penetration made by a preload The indenter is forced into the specimen under a

preliminary load When equilibrium is reached a measuring device follows the movements of the

indenter and responds to changes in depth of penetration of the indenter While the preload is still being

applied additional major load is applied resulting in increased penetration When equilibrium is reached

again the major load is removed but the preload is maintained Removing the major load allows partial

recovery and reduces the depth of penetration The permanent increase in depth of penetration resulting

from the application and removal of the major load is used to calculate the Rockwell number using the

relation

HR = E ndash e

Where E is a constant depending on the form of the indenter 100 units for diamond indenter and 130

units for steel ball indenter e is the permanent increase in depth of penetration due to the major load

measured in units of 0002mm

Fig 2-7 Rockwell Indentation

When testing materials indentation hardness is related linearly to the tensile strength The important

relation permits economically important nondestructive testing of bulk metal deliveries with lightweight

equipment like the Rockwell tester shown below in figure 2-7

Fig 2-8 Rockwell Hardness Tester

20

There are different scales denoted by a single letter that use different loads or different indenters

The result is a dimensionless number denoted as HR X where X will be the letter denoting the scale as

shown below in table 2-1

Table 2-1 Rockwell Hardness Test Scale

Differential depth hardness measurement was first conceived in 1908 by Viennese professor Paul

Ludwik It eliminated the errors associated with the mechanical imperfections of the system such as

backlash and surface imperfections in the specimen Rockwell testing has an advantage over Brinell

testing because the latter was slow itrsquos not useful on fully hardened steel and left too large an impression

to be considered nondestructive

The tester was co-invented by Hugh M Rockwell and Stanley P Rockwell The requirement for this

tester was to quickly determine the effects of heat treatment on steel bearing races

21

223 Vickers Hardness Test HV

This is a type of microindentation hardness test where a diamond indenter of specific geometry is

impressed into the surface of the test specimen using a known applied force ranging from 10 to 1000

grams This type of tests usually has forces of 2N and produce indentations of about 50μm They can be

used to observe changes in hardness on the microscopic scale It is difficult to standardize the

microhardness measurements because it has been found that the microhardness of almost any material is

higher than its macrohardness The values also vary with load and work-hardening effects of materials

The Vickers test is often easier to use than other hardness tests because the required calculations are

independent of the size of the indenter and the indenter can be used for all materials It can be used for all

metals and has one of the widest scales among hardness tests The unit of the Vickers test is denoted as

HV and can be converted to units of Pascal (Pa) but it is not a measurement of pressure The hardness

number is determined by the load over the surface area of the indentation and not the area normal to the

force

A square-based pyramid shaped diamond is use as the indenter It has been established that the ideal

size of a Brinell impression was 38 of the ball diameter As two tangents to the circle at the ends of a

chord 3d8 long intersect at 136plusmn05deg it was decided to use this as the angle of the indenter giving an

angle to the horizontal plane of 22deg on each side The HV number is determined by the ratio FA where F

is the force applied to the diamond in kgf and A is the surface area of the resulting indentation in mmsup2 A

can be determined by the relation

A =

Where A is the surface area of indentation and d is the average length diagonal left by the indenter

This can be approximated as

A =

Then the Vickers Number is

HV =

=

Vickers hardness number is reported as xxxHVyy or xxxHVyyzz (if duration of applied force differs

from 10s to 15s) where xxx are replaced by the hardness number yy is the load in kg and zz indicates

loading time The values are generally independent of test force

The test was developed in 1921 by Robert L Smith and George E Sandland at Vickers Ltd as an

alternative to Brinell method to measure the hardness of materials

22

Fig 2-9 Vickers Indentation Fig 2-10 Vickers Hardness Tester

23 AR Coating

231 Bose-Einstein Condensate

The Bose-Einstein Condensate or BEC is a state of matter of a dilute gas of bosons cooled to

temperatures very near absolute zero around 0K or -27315degC Under such conditions a large fraction of

the bosons occupy the lowest quantum state where the quantum effects become apparent on a

macroscopic scale This gave birth to the Bose-Einstein Statistics which are the rules that govern the

behavior at this state It is one of the two possible ways in which a collection of indistinguishable particles

may occupy a set of available discrete energy states The aggregation of particles in the same state

accounts for the cohesive streaming of laser light and the frictionless creeping of superfluid helium (an

application discussed later) Bose and Einstein recognized that a collection of identical and

indistinguishable particles can be distributed this way This theory applies only to those particles not

limited to single occupancy of the same state particles that do not obey the Pauli Exclusion Principle

restrictions Such particles are the Bosons named after the statistics that correctly describe their behavior

This phenomenon was first predicted by Satyendra Nath Bose around 1924 when he considered how

groups of photons behave He then asked Albert Einstein for help publishing his discoveries to which

Einstein agreed and gave follow up supporting these findings The resulting efforts became the concept of

a Bose gas governed by the Bose-Einstein Statistics described above Einstein demonstrated that cooling

bosonic atoms to a very low temperature would cause them to condense into the lowest accessible

quantum state resulting in a new form of matter

The first gaseous condensate we produced by Eric Cornell and Carl Wieman at the University of

Colorado at Boulder NIST ndash JILA lab sung a gas of rubidium atoms cooled to 170 nK which earned

them the 2001 Nobel Prize in physics together with Wolfgang Ketterle from MIT The transition to BEC

occurs below a critical temperature which for a uniform three dimensional gas consisting of

non-interacting particles with no apparent internal degrees of freedom is given by

23

Tc =

(

)

asymp 33125

Where Tc is the critical temperature n is the particle density m is the mass per boson h is the

reduced Planck constant k is the Boltzmann constant and ζ is the Riemann zeta function

There are two classes of elementary particles defined by whether their quantum spin is a nonnegative

integer or an odd half integer A Bose-Einstein Condensate is shown below in figure 2-11

Fig 2-11 Bose Einstein Condensate at different scales

Bosons are the particles whose quantum spin is a nonnegative integer (s = 0 1 2 etc) Examples of

bosons include fundamental particles (Higgs Boson Photons W and Z Bosons Gluons Gravitons etc)

composite particles (Mesons Hadrons Nuclei and Atoms of Carbon-12 and Helium-4) and

quasi-particles Bosons are considered force carrier particles The Bosons differ from Fermions in that

there is no limit to the number that can occupy the same quantum state This is called the Pauli Exclusion

Principle

The Pauli Exclusion Principle says that no two identical fermions may occupy the same quantum state

simultaneously in other words this means that the total wave function for two identical fermions is

anti-symmetric with respect to exchange of the particles This means that no two electrons in a single

atom can have the same four quantum numbers

Fermion is any particle characterized by Fermi-Dirac Statistics and follows the Pauli Exclusion

Principle described above Quarks Leptons and composite particles (Hadrons Nuclei and Atoms of

Carbon-13 and Helium-3) made of an odd number of these are considered Fermions It can be an

elementary particle such as the electron or a composite particle such as the protons Following the Pauli

24

Exclusion Principle only one fermion can occupy a particular quantum state at any given time If multiple

fermions have the same spatial probability distribution then at least one property of each fermion must be

different Fermions are usually associated with matter because composite fermions are key building

blocks of matter (neutrons and protons)

Fermionsrsquo behavior by the Fermi-Dirac Statistics which describes the energies of single particles in a

system comprising of many identical particles It applies to identical particles with half-odd integer spin

in a system of thermal equilibrium The particles in the system are assumed to have negligible mutual

interaction This allows the many-particle system to be described in terms of single-particle energy states

The result is the Fermi-Dirac distribution of particles over these states and includes the condition that no

two particles can occupy the same state which has considerable effect on the properties of the system

In quantum mechanics the position of an object is uncertain An object has a definite probability of

being at any given point in space This probability is encoded in the wave function mentioned earlier If

one concentrates a large number of identical bosons in a small region then it is possible for their wave

functions to overlap so much that the bosons lose their identity When this happens thatrsquos a Bose-Einstein

Condensate It is only possible at very low temperatures because at high temperatures the individual

bosons have small wave functions and move rapidly which causes them to fly apart

For now applications are still restricted because there are still some setbacks regarding BECs They

are extremely fragile they are being produced in small quantities with just a few million atoms at a time

and finally they can only be made from certain types of atoms Some examples are the atom laser Ketterle

in which a conventional light lase emits a beam of coherent photons this means they are all in phase and

can be concentrated to an extremely small bright spot BECs can slow down light as demonstrated by

Prof Lene Hau PhD in 2001 by the use of a superfluid [7] These manipulations could develop into

new types of telecommunications technology optical storage and quantum computing

BECs are related to super-fluidity and super-conductivity Super-fluidity is the state of matter in

which the behavior is that of a fluid with zero viscosity It was discovered in liquid helium but now it has

applications in astrophysics high-energy physics and theories of quantum gravity

Super-conductivity is a phenomenon of exactly zero electrical resistance and expulsion of magnetic

fields occurring in certain materials when cooled below a characteristic critical temperature A

super-conductor is shown below in figure 2-12

Fig2-12 Super Conductor

25

232 AR Coating Basic Principles

Anti-reflective (AR) coating is a type of optical coating applied to the surface of lenses and other

optical devices (in our case we planned to apply it to a laser diode) to reduce reflection This improves

the efficiency of the system since less light is lost The primary benefit is the elimination of the reflection

itself

When light the medium (glass) it will produce reflection if 100 of the light comes from the air and

enters the glass because therersquos a difference between the index of refraction some of the light will go out

and when the light is coming out of the glass into the air once again because of the difference between

index of refraction some of the light wonrsquot be able to pass through the medium

When the light makes the first trip into the glass there was a loss of about 4 in the reflection and

when the light makes the trip back outside there was another loss of about 4 so when we assume that

100 of the light interacts with the medium actually therersquos just about 92 acting (we neglect the light

absorbed by the glass around 05) To illustrate this idea please refer to figure 2-13

Fig 2-13 Simple Model for Light in Glass Medium

When we apply the AR Coating the light that enters will only have a loss of about 05 and when

making the trip back outside again only 05 of light is loss so we get the result of increasing the light

passing through up to 99 (again neglecting the light absorbed by the glass around 05) To illustrate

this idea please refer to figure 2-14

26

Fig 2-14 Simple Model for Light in Glass Medium after AR Coating

The AR Coating can reduce reflection of incoming light In the case that light hits perpendicular to

the surface of the medium the intensity of the reflection can be calculated using the Reflection

Coefficient

Where n0 and ns are the refractive indices of the first and second media respectively The value of R

varies from 0 (no reflection) to 1 (all light reflected) and is usually quoted as a percentage

Complementary to R is the transmission coefficient or Transmittance If absorption and scattering are

neglected then the value of Transmittance is always 1-R then if a beam of light with intensity I is

incident on the surface a beam of intensity RI is reflected and a beam with intensity TI is transmitted to

the medium

The optimal value is called the Optimal Index of Refraction and is described as

For glass with ns around 15 in air (n0 around 10) then the optimum refractive index will be n1 =

1225

To reduce the refraction in this case we now mean the one that is produced inside the chamber of the

Laser diode the easiest way is to apply a low reflectivity AR coating on the surface of the laser To

measure the appropriate thickness of the coating layer we can use the equations described above By

applying a coat exactly

thickness film we can assure that a certain wavelength is transmitted The

27

reflected waves from the back of the glass medium will be half a wavelength out of phase So they

interfere destructively Because all reflected waves are interfered the maximum amount of light passes

through the coating Please refer to figure 2-15 to illustrate this idea

Fig 2-15 Light Passing through AR Coat and Glass

The most common process to attain this final product is by vacuum deposition For the best coating

results we need to lower the pressure inside the vacuum system to torr

Fig 2-16 Lens without (Top) and With (Bottom) AR Coating

28

233 Laser Diode Basic Principles

A laser diode is a laser whose active medium is a semiconductor similar to that found in

light-emitting diodes (LEDs) Please refer to figure 2-17 The most common type of laser diode is formed

from a p-n junction and powered by injected electric current

Fig 2-17 Laser Diode

Laser diodes are formed by doping a very thin layer on the surface of a crystal wafer The crystal is

doped to produce the n-type region and a p-type region one above the other

By referring to figure 1-2 we can see the basic structure of a working laser When the laser diode has

a current passing through it the light will get excited inside its gain medium and then will start to

resonate this process is called pumping The current exceeds the critical current and then it comes out as

laser light Please refer to figure 1-3 Since we use an external cavity laser we need to apply the AR

coating to the diode and adjust a diffraction grating The laser light comes out the diode and bounces on

the grating making the resonance externally and this becomes the ldquocavityrdquo as shown in figure 2-18

Fig 2-18 Tunable Laser Basic Configuration

29

The most important feature of the external cavity laser is that we can adjust the wavelength easily just

by changing the diffraction gratingrsquos angle and in the end this is the output wavelength of the laser For

different wavelengths there will be different levels of visible light as shown in figure 2-19

Fig 2-19 Light Spectrum

234 Quartz Microbalance System

A Quartz Crystal Microbalance is an instrument that measures a mass per unit area by measuring the

change in frequency of a quartz crystal resonator The resonance is disturbed by the addition or removal

of a small mass due to oxide growthdecay or film deposition (which is the case in our study) at the

surface of the acoustic resonator The QCM can be used under vacuum in gas phase and more recently in

liquid environments It is useful for monitoring the rate of deposition in thin film deposition systems

under vacuum Frequency measurements are easily made with high precision

For our research we used the Sigma Instruments SQM-160 RateThickness Monitor shown in figure

2-20

Fig 2-20 Front and Back Panels of SQM-160

30

The microbalance uses Quartz as the resonator Quartz is one member of the family of crystals that

experience the Piezoelectric Effect

Piezoelectricity is the charge that accumulates in certain solid materials in response to applied

mechanical stress It means electricity resulting from pressure It was discovered in 1880 by Jacques and

Pierre Curie It is understood as the linear electromechanical interaction between the mechanical and the

electrical state in crystalline materials with no inversion symmetry It is a reversible process in that

materials exhibiting direct piezoelectricity also exhibit the reverse This means that the internal generation

of electrical resulting from applied mechanical force and vice versa

By using the piezoelectric effect we can probe as an acoustic resonance by electrical means Applying

alternating current to the quartz crystal induces oscillations This creates a shear wave We can use these

qualities to determine the resonance frequency at high accuracy

The frequency of oscillation of the crystal is partially dependent in the thickness of the crystal During

normal operation all the variables are held constant so a change in thickness correlates directly to a

change in frequency As mass is deposited or etched away the thickness increases or decreases and so the

frequency of oscillation changes accordingly With some simplifying assumptions the frequency change

can be quantified and correlated precisely to the mass change using the Sauerbreyrsquos Equation

Developed by G Sauerbrey in 1959 it is a method for correlating changes in the oscillation

frequency of a piezoelectric crystal with the mass deposited on it It is defined as below

Where f0 is the Resonant frequency Δf is the Frequency change Δm is the mass change A is the

piezoelectrically active area of the crystal q is the Density of quartz (2648 gcmsup3) and μq is the Shear

modulus of quarts(2947x gcmssup2)

Because the film is treated as an extension of thickness Sauerbreyrsquos equation only applies to systems

in which the following 3 conditions are met

Deposited mass must be rigid

Deposited mass must be distributed evenly

The frequency change

lt002

If the change is greater than 2 the Z-match method must be used to determine the change in mass

It is defined as

Where fL is the frequency of the loaded crystal fU is the resonant frequency Nq is the frequency

constant (1668x HzAring) Δm is the mass change A is the piezoelectrically active area of the crystal

31

q is the density of quartz Z is the method constant f is the density of film μq Is the shear modulus of

quarts and μf is the shear modulus of film

The Sauerbrey equation cannot be applied to systems under liquid medium

The crystals are seed crystals plated with gold on both top and bottom for applications A crystal is

shown in figure 2-21 The QCM consists of a thin piezoelectric plate with electrodes evaporated on both

sides Due to the piezoelectric effect AC voltage across the electrodes induces a shear deformation and

vice versa The electromechanical coupling provides a simple way to detect an acoustic resonance by

electrical means

The Z also called Z-factor is a constant value for different materials and it is shown together with the

density of different materials in table 2-2 below

Fig 2-21 QCM Crystals

The Oscillator of the SQM-160 is shown in figure 2-22 and the equivalent circuit for the Resonant

Oscillator is shown in figure 2-23

Fig 2-22 SQM-160 Oscillator

32

Fig 2-23 Oscillator Circuit

33

Table 2-2 Z-Ratios for Different Materials

Table 2-2 Continued

34

Table 2-2 Continued

35

Table 2-2 Continued

36

Table 2-2 Continued

37

Table 2-2 Continued

38

Table 2-2 Continued

235 Vacuum Chamber System

Vacuum Evaporation is the process of depositing thin films of materials onto surfaces The technique

consists of pumping a vacuum chamber to pressures of less than torr and heating a material to

produce a flux of vapor in order to deposit the material onto a surface The material to be vaporized is

typically heated until its vapor pressure is high enough to produce a flux several Angstrom per second by

using an electrically resistive heater or bombardment by a high voltage beam The process was invented

by Henri Nestle in 1886 for food industry

In here the system has been pumped to a vacuum of Torr When a high current is passed

through the filament boat the filament boat is heated over the desired metal evaporation temperature and

so evaporation starts When the evaporation process is finished and the metal cools down crystals

condensate in the surface of the wafer From the weight of the evaporated material the distance between

the filament boat and the wafer we are able to calculate the deposition thickness and we can also use the

mass detector follower like the Quartz crystal resonator microbalance system In the process of

evaporation we usually use a board in between the filament boat and the wafer This is because before we

arrive to the desired evaporation temperature there will be some impurities that will be vaporized in the

controlled environment so we first use a small current and the board in between to get rid of those

impurities and this raises the purity of the deposition material

39

A vacuum evaporation system is shown in figure 2-24

Fig 2-24 Vacuum Evaporation System

Rough Vacuum 760 ~ 1 torr

Medium Vacuum 1 ~ torr

High Vacuum ~ torr

Ultra-High Vacuum Lower than torr

Table 2-3 Classification of Vacuum

For our study we need to use a Turbo Pump A regular turbo pump is shown in figure 2-25

Fig 2-25 Turbo Pump

For our research we used the Pfeiffer TCP 015 Electronic Drive Unit and Granville Phillips 375

Convectron shown below in figure 2-26

40

Fig 2-26 Control and Measurement Equipment

The electronic drive controls the turbo pump and the Convectron measures the pressure inside our

chamber The turbo pump is a type of vacuum pump used to maintain high vacuum Most turbo pumps

are centrifugal When we start the pumping we need to use a mechanical pump so as to decrease the

pressure inside the system from constant atmospheric pressure to torr and then the use dispersion

pump to continue the vacuum until we get to the desired pressure We need to notice though when we

start the dispersion pump we canrsquot turn off the mechanical pump and they both need to run together If

we need to turn off the pumping we first turn off the dispersion pump wait for it to completely stop and

then turn off the mechanical pump

Our completely assembled system is shown in figure 2-27 below

Fig 2-27 Complete System

41

Chapter 3 TENSILE TESTING IN DEPTH

31 Experimentrsquos Purpose and Principles

By means of Universal testing machine and Strain gauges we were able to observe discuss and

analyze the phenomena created when a specimen of certain material is manipulated under an external load

and determine the stress strain and deformation values later we can use the graphing methods of

stress-strain diagram to describe it

The main point of this experiment is that after the tensile specimen is tested use computer analysis

and the actual strain data and after statistical adjustment make the final results report (Tensile testing

experiment is in accordance with ASTM E8)

32 Experimentrsquos Equipment

321 Universal Testing Machine

For the materials testing experiment part of this research we use a Universal Testing Machine as

shown in figure 31 The maximum load it can apply is 100 Ton After the test specimen is secured on the

device with the use of instrumentation the load exerted and the effects of this become apparent on the

specimen and even the smallest of changes can be recorded For our research we used the Chun Yen

Testing Machines Co Ltd 100 Ton Micro Computer Universal Tensile Tester

Fig 31 Universal Testing Machine

42

Table 31 shows the specifications for this machine

Max Capacity 100 Ton

Accuracy plusmn1

Tension (mm) Max Space 1150mm

Grip for Rod 20-70mm

Ram Stroke 250mm

Effective Column Interval 940mm

Crosshead Speed 300mmmin

Testing Speed 0-50mmmin

Volume of Machine 1700times1000times3350mm(LtimesWtimesH)

Volume of Control Panel 1000times800times1500mm(LtimesWtimesH)

Weight 8000kg

Power 3∮220V 20A

Computer AMD K6-2-350

OS Windows XP

Screen 15rdquo CRT

Table 3-1 Chun Yen Testing Machine Specs Table

The connections diagram is shown in figure 3-2

Fig 3-2 Diagram for System Connections

43

When the test specimen is placed when the external force is applied the Load Cell can measure the

size of the applied force and the Encoder measures the expansion rate of change The Local Controller

receives all the information from the 2 units after arranging the results they are displayed in the

computer and they can be afterwards submitted for more complex analysis such as Finite Element

Analysis and we can get the Stress-Strain Diagram

322 Strain Measurement Equipment

The equipment used in our research provides a four-channel measurement that means we can use up

to 4 strain gauges at a time to do our measurements and provides 3 different bridge arrangements as

shown in figure 3-3

(a) (b) (c)

Fig 3-3 Input Connections for Strain Indicator

Figure 3-3 (a) is the Quarter Bridge (b) is the Half Bridge and (c) is the Full Bridge and Transducers

For our study we used the Quarter Bridge and use the Strain Gauge values to decide the position of the

connecting wires The Strain indicator is shown in figure 3-4

Fig 3-4 Vishay Micro-Measurements Model P3 Strain Indicator and Recorder

44

Input Connections Tool Free eccentric lever release

4-channel input

Wire diameter16-28AWG

Bridge Configurations Quarter- Half- and Full Bridge

Bridge Impedance 60-2000Ω

Display 128 64 pixel FSTN positive gray LCD

Data Conversion AD Converter filter

Measurement Range Resolution Strain Range plusmn155mVV

Resolution plusmn00005mVV

Measurement Accuracy plusmn01 of reading plusmn3 counts

Gage Factor Control 0500-9900

Balance Control Software either manual or automatic

Bridge Excitation 15VDC nominal

Communication Interface USB Cable Included

Data Storage Removable Media Card

Shunt Calibration Across bridge completion resistors controlled

by software When Gage Factor=200

120Ω350Ω1000Ω

Analog Output Value 0 to 25V max

Ranges plusmn320 microε plusmn3200 microε plusmn32000 microε

Error 05 output voltage +5mV

Max Error 14 output voltage + 20mV

Update rate 480 samplessec

Output Load 2000Ω

Power Battery Two Alkaline D cells

Battery life 400 hours typ

USB 5V 100mA

Operational Environment Temperature 0-50

Humidity Up to 90 Non-condensing

Case Aluminum Alloy

Size and Weight 228times152times152(mm) 20(kg)

Table 3-2 Vishay Micro-Measurements Model P3 Strain Indicator and Recorder Specs

45

323 Strain Gauge

The strain gaugersquos main basic principle is to use a resistancersquos characteristics to measure the strain

The inside connections of the strain indicator are shown in figure 3-5

Fig 3-5 Inner Connections

As shown above this is a quarter-bridge connection We connect equal-length 3 wires to the 2

connections allowed by the strain gauge wire 1 and 3 can be used to cancel out the effects of temperature

to the resistance and because of the addition of wires 1 and 3 wire 2 can directly measure the experiment

results from the strain gauge and therefore the strain developed with no influence of temperature

If there were no two measuring leads then the relations will be

R 4 =R g +2R L

Where Rg is the Strain Gauge Value and RL is the wire resistance then

4

4

R

R=

Lg

g

RR

R

2

=

gL

gg

RR

RR

21

amp

4

4

R

R=

g

g

R

R(1- L)

Where L is the Signal Loss Factor and so

L =gL

gL

RR

RR

21

2

g

L

R

2R if

g

L

R

2Rltlt1

46

(Actual Value R g =120R L =08g

L

R

2Ris always much smaller than 1)

R 4 =R g +2R LR 2 =R 3 =rR gR 1 =R g 32 RR =0

V 0 =V 2)1( r

r

(

4

4

R

R-

1

1

R

R)

The first term describes loss attenuation effects second term describes loss of balancing capabilities

effects

V 0 =V 2)1( r

r

[

)2

(Lg

g

RR

R

+

T

Lg

g

RR

R

)

2( + T

Lg

L

RR

R

)

2

2( -(

g

g

R

R) T ]

The first term describes loss attenuation effects and loss of balancing capabilities effects the second

third and fourth terms describe the temperature effects on the wire

For the three-wire method we have

L =gL

gL

RR

RR

1

g

L

R

R if

g

L

R

Rltlt1

V 0 =V 2)1( r

r

[

)(Lg

g

RR

R

+

T

Lg

g

RR

R

)( + T

Lg

L

RR

R

)

2( -

T

Lg

g

RR

R

)( - T

Lg

L

RR

R

)

2( ]

V 0 = V2)1( r

r

)(

Lg

g

RR

R

In the last four terms inside parenthesis we can see the effects of temperature being cancelled out and the

effect on first term is not great so this is the reason why in our research we use three wires

47

324 Specimen Measurements

The tensile specimens used in this research are compliant of ASTM E8 Tensile parameters as shown

in figure 3-6

Fig 3-6 Tensile Specimen

Diameter

D(mm)

Gauge

Length

G(mm)

Smallest

Arc

Radius

R(mm)

Shortest

Area

A(mm)

Total

Length

L(mm)

Clamping

Area

Length

B(mm)

Clamping

Area

Diameter

C(mm)

Bar 125 02 625 01 gt10 gt75 ~ 145 ~ 35 20

Table 3-3 Specifications for Round Bar

33 Experiment Procedure

1 Attaching the Strain Gauge to the Tensile Specimen

(1) Prepare 1 ASTM E8 compliant tensile specimen round bar as shown in figure 3-7

(2) Prepare Strain Gauge as those described in table 3-4

(3) Prepare other consumables and adhesive agent such as epoxy adhesive or

cyanoacrylate adhesive as shown in figure 3-8

48

Fig 3-7 Actual Tensile Specimen

Fig 3-8 Other Materials Used (Such as Alcohol gauze transparent tape adhesive)

Gage Type

EA-06-120LZ-120E

Resistance in ohms at 24∘C

1200plusmn03

Gage Factor at 24∘C

2075plusmn05

Transverse Sensitivity at 24∘C

(+07plusmn02)

Table 3-4 Specifications for Strain Gauge

2 Attaching Strain Gauge

As shown in following figures we shall explain the attachment of the strain gauge

(1) Use sand paper and a rasp to clean thoroughly the surface where the strain gauge will be

attached to

49

(a)

(2) Use alcohol to wash the surface where the strain gauge will be attached and use gauze to rub

it off

(b)

(3) Find a clean surface and clean it with alcohol and gauze

(c)

(4) Place the strain gauge in the clean surface Use a piece of transparent tape on top of the strain

gauge after securely placed rip it off the surface carefully

50

(d)

(5) Use a piece of white paper to mark the place where the strain gauge will be attached and in

this way we can make sure that the strain gauge will be placed as horizontally and vertically

correct as possible

(e)

(6) In the place where we had our mark place the strain gauge

(f)

(7) Carefully lift one side of the tape and apply some of the adhesive agent to both the strain

gauge and specimenrsquos surface

(g)

51

(8) We need to make sure that the gauge and the specimen will be firmly attached so we gently

apply pressure with our thumb

(h)

(9) After the adhesive is fully dry we can carefully rip off the tape

(i)

(10) We need to do the whole process twice one for the horizontally placed strain gauge and one

for the vertically placed strain gauge

52

(j)

(11) We now proceed to solder the wires to the strain gauge

(k)

(12) After soldering we use a Volt Multimeter to measure that there is no contact between wires

If there is none then the specimen is ready for testing

(l)

(13) We now need to measure a 5cm distance and mark it to check and compare the elongation

before and after the tensile testing

(m)

53

Fig 3-9 Specimen-Strain Gauge Process

3 Tensile Test

(1) Enter the computer application that controls the tensile testing machine

(2) Turn on the tensile testing machine main switch

(3) Adjust the hydraulic pump to go back to its original position

(4) Bring the lowering motor down to a distance enough so as to attach the tensile specimen to the

system open the clamps and secure the specimen

(a)

(5) Connect all the necessary wires to the strain indicator equipment

54

(b)

(6) Start the ascending motor and wait for the expansion

(c)

Fig 3-10 Specimen-Tensile Testing Process

4 Start the Test

(1) Enter the software application and enter some variables needed for the experiment in the

specific screen

(2) Go back to the main screen and press the [測試] (measure) button to start the test and auto

recording in the software

(3) After the specimen breaks the mechanical device will automatically stop and ask the user to

enter the total displacement We take out the specimen from the testing machine and adjust the

machinersquos position back to its original position

(4) Save the results information

(5) Record the results from the strain indicator

34 Results

From this experiment we can get the Poissonrsquos Ratio Youngrsquos Modulus and Yield Strength etc and

because of the slippage phenomenon in the clamp at the moment of the test then the Elastic Limit will

display some yield phenomena So omit any undesirable results we just take the Yield portion of the

results as reference

In the process of the experiment the most important part to attend to is the attaching of the strain

gauge because the gaugersquos purpose is to measure the strain developed during the test and this strain

might be very small If the gaugersquos angle change during the test ie is not well attached this will affect

the accuracy of the measurements of Poissonrsquos ratio and Youngrsquos modulus

55

The materials provided by the manufacturer are SUM 23 and SUM 43 steel round bars and these two

types of materials have been through different heat treatment processes so they can be sub-divided

further into untreated material heat-treated material and black surface heat treated material for the two

materials with heat treatment the treatment process and finished are different In the end we only have

the mechanical properties that were calculated after our research of these materials

All of the specifications are identical to those shown in figure 3-6

341 SUM 23

Fig 3-11 SUM 23 Untreated Material

Number 7 10

Hardness(HRB) 74 75

Yield Stress (MPa) 448 440

Tensile Strength (MPa) 544 560

Poissonrsquos Ratio 029 027

Youngrsquos Modulus (GPa) 203 210

Cut-off Area Shrinking () 42 41

Elongation () 1125 1011

Table 3-5 Mechanical Properties of SUM 23 Untreated

56

Stress-Strain Diagram

(a)

(b)

57

Fig 3-12 Stress-Strain Diagrams for (a) 7 Round Bar and (b) 10 Round Bar

Cut-Off Area

(a)

(b)

Fig 3-13 Cut-Off Area of (a) 7 Round Bar and (b) 10 Round Bar

58

SUM 23 Nickel Round Bar

Fig 3-14 SUM 23 Nickel Material

Number 1 2 3 4

Hardness(HRB) 48 50 49 48

Yield Stress (MPa) 370 370 380 400

Tensile Strength (MPa) 455 451 450 450

Poissonrsquos Ratio 028 046 029 026

Youngrsquos Modulus (GPa) 243 303 246 206

Cut-off Area Shrinking () 803 803 726 601

Elongation () 566 65 602 647

Table 3-6 Mechanical Properties of SUM 23 Nickel

59

Stress-Strain Diagram

(a)

60

(b)

(c)

(d)

61

Fig 3-15 Stress-Strain Diagrams for (a) 1 Round Bar (b) 2 Round Bar (c) 3 Round Bar and (d)

4 Round Bar

Cut-Off Area

(a)

(b)

62

(c)

(d)

Fig 3-16 Cut-Off Area of (a) 1 Round Bar (b) 2 Round Bar (c) 3 Round Bar and (d) 4 Round

Bar

63

SUM 23 Black Surface Round Bar

Fig 3-17 SUM 23 Black Surface Material

Number 1 2 3

Hardness(HRB) 51 50 51

Yield Stress (MPa) 378 371 369

Tensile Strength (MPa) 467 465 464

Poissonrsquos Ratio 03 016 04

Youngrsquos Modulus (GPa) 215 266 266

Cut-off Area Shrinking () 986 94 848

Elongation () 748 805 761

Table 3-7 Mechanical Properties of SUM 23 Black Surface Material

64

Stress-Strain Diagram

(a)

(b)

65

(c)

Fig 3-18 Stress-Strain Diagrams for (a) 1 Round Bar 2 Round Bar and (c) 3 Round Bar

Cut-Off Surface

(a)

66

(b)

(c)

Fig 3-19 Cut-Off Surface of (a) 1 Round Bar 2 Round Bar and (c) 3 Round Bar

67

342 SUM 43

Fig 3-20 Untreated SUM 43 Untreated Material

Number 1 5

Hardness(HRB) 76 75

Yield Stress (MPa) 572 594

Tensile Strength (MPa) 743 785

Poissonrsquos Ratio 027 029

Youngrsquos Modulus (GPa) 200 202

Cut-off Area Shrinking () 338 2944

Elongation () 857 894

Table 3-8 Mechanical Properties of SUM 43 Untreated

68

Stress-Strain Diagrams

(a)

(b)

Fig 3-21 Stress-Strain Diagrams for SUM 43 (a) 1 Round Bar and (b) 5 Round Bar

69

Cut-Off Area

(a)

(b)

Fig 3-22 Cut-Off Area of SUM 43 (a) 1 Round Bar and (b) 5 Round Bar

70

SUM 43 Nickel Round Bar

Fig 3-23 SUM 43 Nickel Material

Number 4 5

Hardness(HRB) 51 50

Yield Stress (MPa) 1580 1544

Tensile Strength (MPa) 1639 1625

Poissonrsquos Ratio 03 028

Youngrsquos Modulus (GPa) 194 201

Cut-off Area Shrinking () 1697 137

Elongation () 376 265

Table 3-9 Mechanical Properties of SUM 43 Nickel

71

Stress-Strain Diagrams

(a)

(b)

Fig 3-24 Stress-Strain Diagrams for (a) 4 Round Bar and (b) 5 Round Bar

72

Cut-Off Area

(a)

(b)

Fig 3-25 Cut-Off Area of (a) 4 Round Bar and (b) 5 Round Bar

73

SUM 43 Black Surface Material

Fig 3-26 SUM 43 Black Surface Material

Number 3 5

Hardness(HRB) 56 56

Yield Stress (MPa) 1416 1361

Tensile Strength (MPa) 1591 1402

Poissonrsquos Ratio 029 031

Youngrsquos Modulus (GPa) 200 202

Cut-off Area Shrinking () 139 124

Elongation () 24 24

Table 3-10 Mechanical Properties of SUM 43 Black Surface Material

74

Stress-Strain Diagrams

0 2 4 6 8 10 12 14

-200

0

200

400

600

800

1000

1200

1400

1600

1800

應力 (MPa)

應變()

(a)

0 2 4 6 8 10

-200

0

200

400

600

800

1000

1200

1400

1600

應力

(MPa)

位移 ()

(b)

Fig 3-27 Stress-Strain Diagrams for (a) 3 Round Bar and (b) 5 Round Bar

(Note These curves were formulated using Visual Solutions Inc VisSim Software)

75

Cut-Off Area

(a)

(b)

Fig 3-28 Cut-Off Area of (a) 3 Round Bar and (b) 5 Round Bar

76

The force value (N) was retrieved from the Universal Testing Machine

The Poissonrsquos Ratio (ε) is calculated as

ε =

the values for the Poissonrsquos Ratio are in average around 0297

The Youngrsquos Modulus (E) is calculated as

E =

Where

Stress =

Cross-sectional Area =

where D is the Diameter

The value for D was in average around 1258 mm

The values shown by the computer because there is Slippage phenomena between the Clamp and the

specimen will not be taken into consideration for the elongation strain and Youngrsquos modulus and we will

refer to the values that we have meticulously calculated

77

Chapter 4 AR COATING IN DEPTH

41 Experimentrsquos Purpose and Principles

By means of a vacuum chamber and several other instruments we intend to apply Anti-Reflective

Coating using deposition process to a laser diode and in this way reduce its refraction so as to make it

lose less light in the process of amplification and we can control certain wavelengths we want produced

for certain desired applications in our case we are attempting to re-create a Bose-Einstein Condensate

An optimal BEC apparatus is shown in figure 4-1

Fig 4-1 BEC Apparatus

The main point of this experiment is to build a vacuum chamber system attach all the instrumentation

needed (Vacuum pump deposition meter and voltmeter) and use it to apply AR coating to a laser diode

After we have accomplished the AR coating other team will be in charge of designing the BEC apparatus

and use the results of our research

78

42 Experimentrsquos Equipment

421 Vacuum Chamber

For this research we designed a vacuum chamber whose main body is shown in figure 4-2 Its

dimensions are

Width 240 mm

Length 240 mm

Height 200 mm

Outer Diameter 4 in

Inner Diameter 15 in

Fig 4-2 Vacuum Chamber Main Body

The chamber is made up of 6 pass ways pass way A is the connection with the Laser Deposition

Equipment pass way B is the connection with the Turbo Pump and pass way C is for the connection with

the Deposition Source

A

C

B

79

Pass way C is for the deposition source as mentioned above This is a system where a thermal

resistance is heated by passing a high current through it which heats up a filament boat (made of tungsten)

where the material to be evaporated is place We control the temperature as such that the material will

evaporate and the heat will not cause the filament boat to crack

Because P = Isup2 R (where P is power I is current and R is resistance) to avoid the current to flow

where it is not desired we decided that the material for the Thermocouple shown in figure 4-3 should be

Copper ᴓ 63 mm We choose it that way because Copper has very good heat dissipation characteristics

and the resistance value is low It can reduce the value of the current enough to make the thermocouple to

create heat

Fig 4-3 Thermocouple

To the thermocouple we attach the tungsten filament boat We need to take notice of materials to be

used in this design because when using high current the tungsten filament boar will heat up and so the

material must be able to keep up with the heating potential of tungsten and has a low coefficient of heat

dissipation to avoid the tungsten to fail when heating up and therefore not evaporating Considering all

this we decide to use Stainless Steel

Because this clamp will be assembled inside the chamber after many revisions it was determined it

will have the shape shown in figure 4-4

Fig 4-4 Filament Boat Clamp Design

80

For the tungsten filament boat we bought the product from a distributor The dimensions are

Length 100 mm

Width 10 mm

Height 1 mm

Our thermocouple is 15 in but the pass way C is 4 in so we need to attach a Flange that connects

15in to 4in Because these specifications are quite difficult to achieve by Milling we had to use

electrical wire cutting

For the laser clamping system where the laser that is going to be AR coated will be placed will be

connected to pass way A the assembly is shown in figure 4-5 below

Fig 4-5 Cover Assembly

For this design we used an O-ring instead of a gasket so as to save time The design of the assembly

where the laser will be placed is shown in figure 4-6

Fig 4-6 Upper Cover Inner Assembly

D

E

F

81

Point D is the plate in the assembly where the laser diode will be fixed Because of the easy

processing we decide to use Aluminum and it is screwed to the top cover Point E is the connection for

the Quartz crystal resonator and it is designed in the same as point F in this way the results of the quartz

microbalance system will be more accurate in real time Point F is the final resting place for the laser

diode We use a Thor Labs Base with dimensions of ᴓ 9mm and ᴓ 56mm for two different size laser

diodes It just needs to be plugged in for easy installation

From figure 4-6 we know that the system needs signal system connections and because of the

change in temperature inside the chamber this could affect the functioning of the quartz microbalance so

we also need to install water tubes for cooling This is shown in figure 4-7 below

Fig 4-7 Diagram of Upper Cover Connections

In figure 4-8 we show the Feed through connections and their functions

Fig 4-8 Feed through Diagram

82

1 SQM-160 wire 5 Laser Connection 1 (Vin)

2 SQM-160 (G) 6 Laser Connection 2 (G)

3 K-Type-1 7 Laser Connection 3 (PD)

4 K-Type-2 8 Not In Use

The fully assembled chamber is shown in figure 4-9

Fig 4-9 Fully Assembled Chamber

422 Quartz Crystal Microbalance

For measuring the deposition on our target for coating we used the Inficon SQM-160 RateThickness

Monitor It is an easy to use instrument for measuring many types of thin-film coatings as shown in

figure 4-10

(a) Front Panel (b) Back Panel

Fig 4-10 Inficon SQM-160

83

Table 4-1 shows the technical specifications for this equipment

Number of sensors 2 Standard 4 additional optional

Sensor Frequency Range 40 MHz ~ 60 MHz

Reference Frequency Accuracy 002

Thickness Display Resolution 1 Aring

Thickness Resolution 015 Aring (Std) 0037 Aring (Hi Res)

Density of Stored Films 05-9999 gmcc

Tooling 10-399

Z-Factor 010-1000

Final Thickness 0000-9999k Aring

Measurement Period 15 to 2 sec

Simulation Mode Yes

Frequency Mode Yes

Rate Resolution 011 Arings

Dual Crystal Yes

Etch Mode Yes

Crystal Tooling 10-399

Crystal Fail Min Max 40 to 60 MHz 41 to 61 MHz

Power 100-120 200-240~plusmn10 nominal 20W

Operation Environment 0degC ~ 50degC

0 ~ 80 RH non-condensing

0 ~ 2000 meters

Class 1 Equipment

Pollution Degree 2

Rack Dimensions 885mm x 2127mm x 1969mm

Weight 27 kg

Table 4-1 Inficon SQM-160 RateThickness Monitor Specs

84

To the SQM-160 we need to connect an Oscillator We use the Sigma Instruments Remote Oscillator

Ser No 2 268 as shown in figure 4-11

Fig 4-11 Sigma Instruments Remote Oscillator

The connections diagram is shown in figure 4-12

Fig 4-12 SQM-160 Connections Diagram

85

423 Turbo Pump

For our experiments we used the Pfeiffer TCP 015 Electronic Drive Unit shown below in figure 4-13

Table 4-2 shows the technical specifications for this equipment

(a) Front Panel (b) Back Panel

Fig 4-13 Pfeiffer TCP 015 Electronic Drive

Connection Voltage (100V) 90-112

Mains Frequency 5060 Hz

Start-up Current 22 A

Nominal Frequency 1500 Hz

Rotation Speed 10V = 1500Hz plusmn2

Analog Output Current 10 V = 25 A plusmn 5

Rotation Speed Switchpoint 750 Hz

Works Setting 8 min

Permissible Ambient Temperature 0degC ~ 40degC

Dimensions Front Panel 1285mm x 1063mm

Insertion Length 227mm

Weight 27 Kg

Table 4-2 Pfeiffer TCP 015 Electronic Drive Specs

86

The connections diagram is shown in figure 4-14

Fig 4-14Connections Diagram for Pfeiffer TCP 015

To measure the pressure inside the chamber we use the Granville Phillips 375 Convectron Vacuum

Pressure Controller shown in figure 4-15

(a) Front Panel (b) Back Panel

Fig 4-15 Granville Phillips 375 Convectron

87

Its dimensions are shown in figure 4-16

Fig 4-16 Dimensions of Convectron

Table 4-3 shows the technical specifications for this equipment

Table 4-3 Granville Phillips 375 Convectron Vacuum Pressure Controller Specs

88

424 Multimeter

For our experiment we used the Keithley 2000 Digital Multimeter as shown in figure 4-17

(a) Front Panel (b) Back Panel

Fig 4-17 Keithley Model 2000 6-12-Digit Digital Multimeter

Its technical specifications are shown in table 4-4

Table 4-4 Keithley Model 2000 6-12-Digit Digital Multimeter Specs

89

43 Experiment Procedure

1 Connecting together the equipment and the chamber

(1) We first connect the resonator to the thickness monitor and connect the other side to the

chamber

(2) We now connect the flexible tubes to the turbo pump on one side and to the chamber on the

other

(3) We need to check that tubes are tightly connected to avoid any leaks in the vacuum pumping

process which will not allow us to get to our goal of Torr As shown in figure 4-18

(4) Connect the convectron to the system as shown in figure 4-19

Fig 4-18 checking for leaks using alcohol

Fig 4-19 Convectron attached to System

90

(5) Attach the clamps of the Multimeter to the bottom of the chamber as shown in figure 4-20

(6) Place the Quartz crystal in place

(7) Close tight vacuum chamber

(8) Connect all electrical appliances to power source

Fig 4-20 Multimeter Connections

2 Starting up the System

(1) We turn on all the devices as such Check all systems are ready to function Reset all values

that might be left over from previous tests

(2) Start the thickness monitor and set all values for this experiment In our case we got to testing

the system but not actual coating So we used the simulation mode of the thickness monitor as

shown in figure 4-21

Fig 4-21 Simulation Mode

91

(3) Start the turbo pump Make sure the lid on the vacuum chamber is tightly closed

(4) Start convectron and record initial pressure

(5) Start Multimeter and record initial current

3 Coating Process

(1) If we have the deposition material inside the filament boat the power source for the high

current must be started as well

(2) Record all initial values for thickness current pressure

(3) For an ideal experiment we need a thickness of around 101 nm a pressure of Torr and

a current of 300 A

44 Results

From previous experiments we have shown that we can turn a LED into a laser by means of AR

Coating In figure 4-22 shown below we can compare the actual results of a Diode before and after AR

coating From the blue line we can see that when the diode is at a current of 15mA its light will change

from LED to laser and if we look at the red line its critical current is around 30 to 35 mA

Fig 4-22 AR Coating Comparison for Laser Diodes

This means that the light emitted is not as strong as if the diode had been coated because inside the

chamber there must be some excitation first so the reflectivity of both sides inside the diode must be high

So because of the coating in one of the sides we have opened a door and let the light come out so the

critical current is risen as such and will be higher value than that of before the coating

92

In the following figures we can see the difference between before and after coating in a material The

thickness is around 1016 nm for this material

Fig 4-23 Before Coating

Fig 4-24 After Coating

93

Chapter 5 CONCLUSIONS AND RECOMMENDATIONS

51 Conclusions

For the first part of this independent study taking into consideration the data that came out of our

research and that sent by the provider we can say

1 SUM 23 after heat treatment will unexpectedly develop cracking in the middle of the tensile

testing process and suddenly break

2 Itrsquos possible that in the process of heat treatment to the SUM 23 material the treatment was not

uniform and this will create a pre-loaded moment force on one side that pushes on the other side

of the specimen resulting in material deformation

3 In the process of attaching the strain gauges to the materials it is very easy to make errors due to

poor adhesion or sudden removal in the tensile testing process

For our second part of the independent study the following can be made

1 At the beginning of this independent study we had no idea what Bose-Einstein Condensate was

or what was its purpose After much literature we finally comprehended the basic principles to

put into practice for our research

2 Our systemrsquos basic working principles and equipmentrsquos complexity are a little difficult to grasp

but hopefully we were able to understand enough of it

3 Theoretically from relation between the power and current we can know the advantages and

disadvantages of AR Coating

4 We were able to assemble the system and run test on its functions Even though we were able to

do this there is still much more work left to do with this system

52 Recommendations

For the Tensile Testing the following can be said

1 Ask the provider to check on the process of heat treatment on the SUM 23 material and give

them the information we have gathered through our test so they can correct for the mechanical

properties found if any change is needed

2 To avoid the problem of the inaccuracy of the poor adhesion of strain gauges we can attach

multiple strain gauges to the same one specimen so as to correlate data and improve our results

For the AR Coating the following can be said

1 We need to make sure that there are no physical defects on the main body of the chamber so as to

achieve maximum efficiency in the vacuum process If there was then the vacuum will arrive to

certain point and then start to decrease

2 It would be preferable to add some sort of visual aid that will allow the user to check the inside of

the chamber without actually opening it This will help us determine at what times we should

manipulate the current to better evaporate the substrate

94

REFERENCES

[1] A L Window Strain Gauge Technology Elsevier Applied Science London and New York 2nd

Edition 1992

[2] CC Perry and HR Lissner Strain Gauge Primer McGraw-Hill Book Co Inc New York 1955

[3] James W Dally William F Riley McGraw-Hill 1978

[4] University of Colorado Boulder BEC - What is it and where did the idea come from

httpwwwcoloradoeduphysics2000becwhat_is_ithtml

[5] Ultraslow Light amp Bose-Einstein Condensates Two-way Control with Coherent Light amp Atom

Fields Harvard Hau Lab Dr Lene Vestergaard Hau Optics amp Photonics News 16 1995

[6] The Art of Taming Light Ultra-slow and Stopped Light Harvard Hau Lab Dr Lene

Vestergaard Hau Europhysics News 2004

[7] Nonlinear Optics Shocking Superfluids Harvard Hau Lab Dr Lene Vestergaard Hau Nature

Physics 2007

[8] Model P3 Strain Indicator and Recorder Instruction Manual Vishay Micro-Measurements 2005

[9] Granville-Phillips Series 375 Convectron Vacuum Gauge Controller Instruction Manual Brooks

Automation 2008

[10] Effect of Film Thickness on the Validity of the Sauerbrey Equation for Hydrated Polyelectrolyte

Films Vogt Lin Wu White 2004

[11] Quartz Crystal Microbalance Study of DNA Immobilization and Hybridization for DNA Sensor

Development Chang Zhao 2008

[12] Installation of Strain Gages with SR-4 PrecoatAdhesive Vishay Micro-Measurements 2005

[13] Strain Gauge Measurement ndash A Tutorial National Instruments 1998

[14] Correlation between Vickers Hardness Number and Yield Stress of Cold-Formed Products

Yavuz Tekkaya

[15] httpsenwikipediaorg

Page 10: PC Hinge Materials Testing and AR Laser Diode Coating

10

Chapter 1 INTRODUCTION

11 Motivation and Background

In response that new generation computers are gradually reducing their size the diameter of

the structures of the hinges used by NB computers must also follow but the hinge strength may

also become smaller due to the reduction of diameter and result in the phenomenon of

insufficient strength In addition the disk-type spring that is source of the torque may also be

insufficient due to the narrowing of the structure Therefore it is necessary to direct a structural

analysis of the hinge for the existing laptops so that we can identify the stress concentration

point The stress concentration point is usually the point where material damage behavior is

encountered the easiest and if we can find the point where breaking occurs most often we can

improve the design of the existing structure to enhance the strength of the hinge structure

Second the structure of the hinge is too complicated the traditional mechanics of materials

analysis methods and formulas are no longer suitable for analysis of a wide arrange of hinge

design In recent years finite element analysis methods have been widely applied in various

fields such as electronics machinery aviation and so on

Therefore to meet the need of the industry and with the purpose of reducing design time

how to design a notebook computer hinge without compromising mechanical stability and

materialrsquos hardness which will operate equally under equal conditions In other words be able to

meet the needs of the size decreasing NB computers market as the needs for this kind of

accessories will increase in the near future If we take into consideration the traditional ways of

design we seek to reduce the costs of use of machinery and molding by applying Finite Element

Analysis methods to our study and also increase the flexibility of designing methods

The second project was brought in by Prof Chuang and it is to help in the further research of

the Bose-Einstein condensate This is a state of matter of a dilute gas weakly interacting bosons

(subatomic particles that obey the Bose-Einstein statistics) confined in an external potential and

cooled down to temperatures very near absolute zero (0 K or -27315deg C) Under these conditions

a large number of bosons occupy the lowest quantum state of the external potential at which

point quantum effects become apparent at macroscopic scale This state of matter was predicted

by Satyendra Nath Bose and Albert Einstein in 1924~1925 Then 70 years later the 1st gaseous

condensate was produced by Eric Cornell and Carl Wieman in 1995 at the University of

Colorado (Boulder) NIST-JILA lab and because of this along with Wolfgang Ketterle of MIT

they received the 2001 Nobel Prize in Physics

11

We wish to investigate the properties of Anti Reflecting Coating on laser diodes Hopefully

we will be able to achieve the desired effect of reducing the surface reflection coefficient and

find applications for it

12 Research Objective

We wish to analyze the normal composition of the notebook computerrsquos hinge at which

point in the assembly is clearly the weakest and at this time in the assembly the strength and

durability are influenced The main point is to see if we can affect the normal operation and work

life

The objective of this thesis is to present the results of the material properties under tensile

testing find the mechanical properties and after using finite element analysis determine what

material is the best for our purposes

Fig 1-1 Notebook Computer Hinge

For our second research we wish to produce and analyze laser diodes with anti-reflective

coating and test its properties and applications

When semi-conductor laser has been submitted to current it will produce resonance inside it

and light will be stimulated to come out Please refer to figure 1-2 for the basic structure of a

laser

Fig 1-2 Basic Structure of a Laser

1 Gain Medium

2 Laser Pumping Energy

3 High Reflector

4 Output Coupler

5 Laser Beam

12

But when the laser diode generates light but the laser diode canrsquot produce light on itself it

must wait for the current to be higher than certain value which is called the critical current Until

the light goes over this threshold then it is considered laser light if not it is just considered as a

common LED light source Please refer to figure 1-3

Fig 1-3 Comparison between LED and Laser Diode

As we can see from figure 1-3 all of the light that goes over the critical current is laser light

and so the external cavity semi-conductor laser that we built needs Anti-Reflective Coating

because the method we want to use needs an external cavity laser that has been covered with AR

Coating and a Diffraction Grating We use this configuration first by shooting the laser to the

grating and this will be shot back to the laser creating the external resonance cavity which is

shown in figure 1-4

Fig 1-4 External Cavity Design

13

Two configurations are shown the Littrow Configuration and the Littman-Metcalf

Configuration The Littrow configuration contains a collimating lens and a diffraction grating as

the end mirror The first order diffracted beam provides optical feedback to the laser diode which

has AR Coating The emission wavelength can be turned by rotating the diffraction grating A

disadvantage is that it also changes the direction of the output beam

In the Littman-Metcalf configuration the grating orientation is fixed and an additional mirror

is used to reflect the first order beam back to the laser diode The wavelength can be turned by

rotating that mirror This configuration offers a fixed direction of the output beam and also tends

to exhibit smaller line width as the wavelength selectivity is stronger A disadvantage is that

zero order reflection of the beam reflected by the tuning mirror is lost so that the output power is

less than that of a Littrow laser

13 Methodology

The aim of this research is to find the mechanical properties of materials after being

subjected to tensile testing through finite element analysis observations and determine what

material is best for our purposes taking into consideration the strength and durability of the

material among other properties to find use and applications for the AR coated laser diodes to

further improve the grasp of the Bose-Einstein condensation working principles

14 Organization of the Thesis

The research paper includes five chapters

1 Chapter 1 explains the motivation background objective and methodology of this study

2 Chapter 2 explains the working principles and basic knowledge needed to understand this

study

3 Chapter 3 explains the tensile testing in detail steps methods and results

4 Chapter 4 explains the AR coating in detail steps methods and results

5 Chapter 5 is the conclusions taken from the results shown in chapter 3 and 4 and

recommendations done after arranging and critical thinking

14

Chapter 2 BASICS THEORIES

21 Tensile Testing

After a specimen is tested with the use of tensile testing we can get the Stress-Strain Curve using the

relation between tension and displacement Typical curves are shown in Fig 2-1

(a) Ductile materials (b) Brittle materials

Fig 2-1 Stress-Strain Curve

The curve is unique for each material and is found by recording the amount of deformation at distinct

intervals of tensile or compressive loads Thanks to the use of the Stress-Strain curve we can get very

useful information such as

211 Youngrsquos Modulus (E)

As shown in Fig 2-1 as long as the external load is not greater than the Proportional Limit the Stress

(σ) and Strain (ε) remain as a linear relation fulfilling Hookersquos Law

σ = Eε

The slope is the constant factor the inverse of the modulus of elasticity E also called Youngrsquos

modulus When the external load goes over the proportional limit the stress-strain relationship doesnrsquot

follow the linear relation anymore but the deformation remains flexible When the load is released the

deformation is completely eliminated and the specimen goes back to its original state This is called

15

Elastic Deformation When the external load goes over the Elastic limit only then does the specimen

presents Plastic Deformation This type of deformation which is irreversible even when the load is

removed comes after the material does under elastic deformation so this means the object will first come

part way to its original shape Common metals and ceramics have roughly the same elastic limits

212 Yield Strength and Yield Point

Some materials display very evident yield phenomena while some materials donrsquot as shown in Fig

2-2 After we exceed the elastic limit if we continue to exert load when we arrive to a certain value

which differs under different materials and external conditions there is sudden decrease in stress and this

is called the Yield Strength and can be defined as the stress at which a material begins to deform

plastically using the equation

σyield =

Where P is the tension force and Ao is the original cut-off area

The stress remain at a certain value after the decrease but the strain increases this phenomena can be

easily appreciated when studying the behavior of common Carbon Steel Fig2-2 (a) but most metals (like

Aluminum Copper or High Steel Carbon) donrsquot display this kind of behavior as shown in Fig 2-2 (b)

Arriving to this point is very difficult and the most commonly used method for this is to add a 02 or

0002 offset yield strength to the curve This point is held constant on the strain axis of the curve and

from the 0002 position we draw a straight line parallel to the linear relationship line the point at where

this line and the stress-strain curve intercept is the point we take as the 02 offset yield strength

(a)Evident (b) Non-evident

Fig2-2 Stress-Strain Curve Comparison on Metals

16

213 Ultimate Tensile Strength and Breaking Strength

After materials undergo yield they keep lending strength and hardening phenomena occurs (work

hardening) on the material and the external load increases When it has reached the highest point this is

called the Ultimate Tensile Strength (UTS) as shown in Fig2-1 The UTS is defined as

σUTS =

Where Pmax is the load at the materialrsquos ultimate tensile strength point and Ao is the original cut-off

area For brittle materials the ultimate tensile strength is the most important mechanical property for

ductile materials the ultimate tensile strength is not commonly used for industrial and designing purposes

because upon arriving to this value the material already has forgone great plastic deformation After the

specimen goes through UTS there will be necking phenomena which is a mode of tensile deformation

where relatively large amounts of strain localize disproportionately in a small region of the material It

results from instability during tensile deformation when a materialrsquos cross-sectional area decreases by a

greater proportion than the material strain hardens The specimen continues to elongate until it finally

breaks and the load at this point is called Breaking Strength The breaking strength is defined as the

greatest stress in tension that a material is capable of withstanding without rupture

Where Pf is the load at the materialrsquos breaking strength point and Ao is the original cut-off area

214 Poissonrsquos Ratio (ν)

For elastic deformation when materials are compressed in one direction they tend to expand in the

other two directions perpendicular to the direction of compression This is called the Poissonrsquos Effect

The Poison Ratio is a measure of the Poissonrsquos effect It is the ratio of the fraction of expansion divided

by the fraction of compression for small values of these changes

ν=-

215 Strain Gauge Basic Principles

The strain gauge is a device used to measure the strain of an object Itrsquos an elongated metal resistor

which is attached to the specimen being measured and when the specimen is under strain and starts to

deform the strain gauge will have a change in the resistance With the change in value we can calculate

the elementrsquos strain or elastic modulus and the Poissonrsquos ratio

It takes advantage of the physical property of electrical conductance and its dependence on the

conductorrsquos geometry When the electrical conductor (the specimen being tested) is stretched within the

limits of elasticity such that it does not break or deform plastically it will become narrower and longer

17

which increases the electrical resistance through-out From the measured resistance of the strain gauge

the amount of stress may be inferred by using the relations

R=

Where R is the original resistance value is the electrical resistivity lo is the original length of the

conductor and Ao is the original cross sectional area of the conductor If after the application of tension

the change in length is Δl let the length of the specimen be l = l + Δlo and the tension is the same

through-out So

And the resistance is

The Gauge Factor is the ratio of relative change in electrical resistance to the mechanical strain in

other words it is the relative change in length It is defined as

The strain gauge was invented in 1938 by Edward E Simmons and Arthur C Ruge and the most

common type consists of an insulating flexible backing which supports a metallic foil usually made of a

brass-nickel alloy It is attached to the specimen by a suitable adhesive As the object is deformed the foil

also deforms and this causes the electrical resistance to change Then this is usually measured using a

Wheatstone bridge shown below and is related to the strain by the Gauge Factor

Fig2-3 Basic Structure of Strain Gauge

18

Fig 2-4 Strain gauge attached to Wheatstone bridge

22 Hardness Testing Basic Principles

221 Brinell Scale BHN

The Brinell Scale characterizes the indentation hardness of materials through the scale of penetration

of an indenter loaded on a material specimen The typical test uses a 10mm diameter steel ball as indenter

(usually of value equal to BHN450) with a 29kN force For softer materials smaller force is used The

indentation is measured and BHN is calculated using the relation

BHN =

radic

Where F is the applied force usually within the range of 100 250 500 750 1000 1500 2000 2500

and 3000 kgf D is the diameter of indenter usually within the range of 5mm or 10mm plusmn0005 margin

and d is the diameter of indentation usually around 2mm Its units are of Kgmmsup2 but are not normally

written

First proposed by Swedish engineer Johan August Brinell in 1900 it was the first widely used and

standardized hardness test in engineering and metallurgy although the large size of indentation and

possible damage to specimen limits its usefulness

Fig 2-5 Brinell Indentation Fig2-6 Brinell Hardness Tester

19

222 Rockwell Scale HR

The Rockwell scale is a hardness scale based on the indentation hardness of a material The Rockwell

test determines the hardness by measuring the depth of penetration of an indenter under a large load

compared to the penetration made by a preload The indenter is forced into the specimen under a

preliminary load When equilibrium is reached a measuring device follows the movements of the

indenter and responds to changes in depth of penetration of the indenter While the preload is still being

applied additional major load is applied resulting in increased penetration When equilibrium is reached

again the major load is removed but the preload is maintained Removing the major load allows partial

recovery and reduces the depth of penetration The permanent increase in depth of penetration resulting

from the application and removal of the major load is used to calculate the Rockwell number using the

relation

HR = E ndash e

Where E is a constant depending on the form of the indenter 100 units for diamond indenter and 130

units for steel ball indenter e is the permanent increase in depth of penetration due to the major load

measured in units of 0002mm

Fig 2-7 Rockwell Indentation

When testing materials indentation hardness is related linearly to the tensile strength The important

relation permits economically important nondestructive testing of bulk metal deliveries with lightweight

equipment like the Rockwell tester shown below in figure 2-7

Fig 2-8 Rockwell Hardness Tester

20

There are different scales denoted by a single letter that use different loads or different indenters

The result is a dimensionless number denoted as HR X where X will be the letter denoting the scale as

shown below in table 2-1

Table 2-1 Rockwell Hardness Test Scale

Differential depth hardness measurement was first conceived in 1908 by Viennese professor Paul

Ludwik It eliminated the errors associated with the mechanical imperfections of the system such as

backlash and surface imperfections in the specimen Rockwell testing has an advantage over Brinell

testing because the latter was slow itrsquos not useful on fully hardened steel and left too large an impression

to be considered nondestructive

The tester was co-invented by Hugh M Rockwell and Stanley P Rockwell The requirement for this

tester was to quickly determine the effects of heat treatment on steel bearing races

21

223 Vickers Hardness Test HV

This is a type of microindentation hardness test where a diamond indenter of specific geometry is

impressed into the surface of the test specimen using a known applied force ranging from 10 to 1000

grams This type of tests usually has forces of 2N and produce indentations of about 50μm They can be

used to observe changes in hardness on the microscopic scale It is difficult to standardize the

microhardness measurements because it has been found that the microhardness of almost any material is

higher than its macrohardness The values also vary with load and work-hardening effects of materials

The Vickers test is often easier to use than other hardness tests because the required calculations are

independent of the size of the indenter and the indenter can be used for all materials It can be used for all

metals and has one of the widest scales among hardness tests The unit of the Vickers test is denoted as

HV and can be converted to units of Pascal (Pa) but it is not a measurement of pressure The hardness

number is determined by the load over the surface area of the indentation and not the area normal to the

force

A square-based pyramid shaped diamond is use as the indenter It has been established that the ideal

size of a Brinell impression was 38 of the ball diameter As two tangents to the circle at the ends of a

chord 3d8 long intersect at 136plusmn05deg it was decided to use this as the angle of the indenter giving an

angle to the horizontal plane of 22deg on each side The HV number is determined by the ratio FA where F

is the force applied to the diamond in kgf and A is the surface area of the resulting indentation in mmsup2 A

can be determined by the relation

A =

Where A is the surface area of indentation and d is the average length diagonal left by the indenter

This can be approximated as

A =

Then the Vickers Number is

HV =

=

Vickers hardness number is reported as xxxHVyy or xxxHVyyzz (if duration of applied force differs

from 10s to 15s) where xxx are replaced by the hardness number yy is the load in kg and zz indicates

loading time The values are generally independent of test force

The test was developed in 1921 by Robert L Smith and George E Sandland at Vickers Ltd as an

alternative to Brinell method to measure the hardness of materials

22

Fig 2-9 Vickers Indentation Fig 2-10 Vickers Hardness Tester

23 AR Coating

231 Bose-Einstein Condensate

The Bose-Einstein Condensate or BEC is a state of matter of a dilute gas of bosons cooled to

temperatures very near absolute zero around 0K or -27315degC Under such conditions a large fraction of

the bosons occupy the lowest quantum state where the quantum effects become apparent on a

macroscopic scale This gave birth to the Bose-Einstein Statistics which are the rules that govern the

behavior at this state It is one of the two possible ways in which a collection of indistinguishable particles

may occupy a set of available discrete energy states The aggregation of particles in the same state

accounts for the cohesive streaming of laser light and the frictionless creeping of superfluid helium (an

application discussed later) Bose and Einstein recognized that a collection of identical and

indistinguishable particles can be distributed this way This theory applies only to those particles not

limited to single occupancy of the same state particles that do not obey the Pauli Exclusion Principle

restrictions Such particles are the Bosons named after the statistics that correctly describe their behavior

This phenomenon was first predicted by Satyendra Nath Bose around 1924 when he considered how

groups of photons behave He then asked Albert Einstein for help publishing his discoveries to which

Einstein agreed and gave follow up supporting these findings The resulting efforts became the concept of

a Bose gas governed by the Bose-Einstein Statistics described above Einstein demonstrated that cooling

bosonic atoms to a very low temperature would cause them to condense into the lowest accessible

quantum state resulting in a new form of matter

The first gaseous condensate we produced by Eric Cornell and Carl Wieman at the University of

Colorado at Boulder NIST ndash JILA lab sung a gas of rubidium atoms cooled to 170 nK which earned

them the 2001 Nobel Prize in physics together with Wolfgang Ketterle from MIT The transition to BEC

occurs below a critical temperature which for a uniform three dimensional gas consisting of

non-interacting particles with no apparent internal degrees of freedom is given by

23

Tc =

(

)

asymp 33125

Where Tc is the critical temperature n is the particle density m is the mass per boson h is the

reduced Planck constant k is the Boltzmann constant and ζ is the Riemann zeta function

There are two classes of elementary particles defined by whether their quantum spin is a nonnegative

integer or an odd half integer A Bose-Einstein Condensate is shown below in figure 2-11

Fig 2-11 Bose Einstein Condensate at different scales

Bosons are the particles whose quantum spin is a nonnegative integer (s = 0 1 2 etc) Examples of

bosons include fundamental particles (Higgs Boson Photons W and Z Bosons Gluons Gravitons etc)

composite particles (Mesons Hadrons Nuclei and Atoms of Carbon-12 and Helium-4) and

quasi-particles Bosons are considered force carrier particles The Bosons differ from Fermions in that

there is no limit to the number that can occupy the same quantum state This is called the Pauli Exclusion

Principle

The Pauli Exclusion Principle says that no two identical fermions may occupy the same quantum state

simultaneously in other words this means that the total wave function for two identical fermions is

anti-symmetric with respect to exchange of the particles This means that no two electrons in a single

atom can have the same four quantum numbers

Fermion is any particle characterized by Fermi-Dirac Statistics and follows the Pauli Exclusion

Principle described above Quarks Leptons and composite particles (Hadrons Nuclei and Atoms of

Carbon-13 and Helium-3) made of an odd number of these are considered Fermions It can be an

elementary particle such as the electron or a composite particle such as the protons Following the Pauli

24

Exclusion Principle only one fermion can occupy a particular quantum state at any given time If multiple

fermions have the same spatial probability distribution then at least one property of each fermion must be

different Fermions are usually associated with matter because composite fermions are key building

blocks of matter (neutrons and protons)

Fermionsrsquo behavior by the Fermi-Dirac Statistics which describes the energies of single particles in a

system comprising of many identical particles It applies to identical particles with half-odd integer spin

in a system of thermal equilibrium The particles in the system are assumed to have negligible mutual

interaction This allows the many-particle system to be described in terms of single-particle energy states

The result is the Fermi-Dirac distribution of particles over these states and includes the condition that no

two particles can occupy the same state which has considerable effect on the properties of the system

In quantum mechanics the position of an object is uncertain An object has a definite probability of

being at any given point in space This probability is encoded in the wave function mentioned earlier If

one concentrates a large number of identical bosons in a small region then it is possible for their wave

functions to overlap so much that the bosons lose their identity When this happens thatrsquos a Bose-Einstein

Condensate It is only possible at very low temperatures because at high temperatures the individual

bosons have small wave functions and move rapidly which causes them to fly apart

For now applications are still restricted because there are still some setbacks regarding BECs They

are extremely fragile they are being produced in small quantities with just a few million atoms at a time

and finally they can only be made from certain types of atoms Some examples are the atom laser Ketterle

in which a conventional light lase emits a beam of coherent photons this means they are all in phase and

can be concentrated to an extremely small bright spot BECs can slow down light as demonstrated by

Prof Lene Hau PhD in 2001 by the use of a superfluid [7] These manipulations could develop into

new types of telecommunications technology optical storage and quantum computing

BECs are related to super-fluidity and super-conductivity Super-fluidity is the state of matter in

which the behavior is that of a fluid with zero viscosity It was discovered in liquid helium but now it has

applications in astrophysics high-energy physics and theories of quantum gravity

Super-conductivity is a phenomenon of exactly zero electrical resistance and expulsion of magnetic

fields occurring in certain materials when cooled below a characteristic critical temperature A

super-conductor is shown below in figure 2-12

Fig2-12 Super Conductor

25

232 AR Coating Basic Principles

Anti-reflective (AR) coating is a type of optical coating applied to the surface of lenses and other

optical devices (in our case we planned to apply it to a laser diode) to reduce reflection This improves

the efficiency of the system since less light is lost The primary benefit is the elimination of the reflection

itself

When light the medium (glass) it will produce reflection if 100 of the light comes from the air and

enters the glass because therersquos a difference between the index of refraction some of the light will go out

and when the light is coming out of the glass into the air once again because of the difference between

index of refraction some of the light wonrsquot be able to pass through the medium

When the light makes the first trip into the glass there was a loss of about 4 in the reflection and

when the light makes the trip back outside there was another loss of about 4 so when we assume that

100 of the light interacts with the medium actually therersquos just about 92 acting (we neglect the light

absorbed by the glass around 05) To illustrate this idea please refer to figure 2-13

Fig 2-13 Simple Model for Light in Glass Medium

When we apply the AR Coating the light that enters will only have a loss of about 05 and when

making the trip back outside again only 05 of light is loss so we get the result of increasing the light

passing through up to 99 (again neglecting the light absorbed by the glass around 05) To illustrate

this idea please refer to figure 2-14

26

Fig 2-14 Simple Model for Light in Glass Medium after AR Coating

The AR Coating can reduce reflection of incoming light In the case that light hits perpendicular to

the surface of the medium the intensity of the reflection can be calculated using the Reflection

Coefficient

Where n0 and ns are the refractive indices of the first and second media respectively The value of R

varies from 0 (no reflection) to 1 (all light reflected) and is usually quoted as a percentage

Complementary to R is the transmission coefficient or Transmittance If absorption and scattering are

neglected then the value of Transmittance is always 1-R then if a beam of light with intensity I is

incident on the surface a beam of intensity RI is reflected and a beam with intensity TI is transmitted to

the medium

The optimal value is called the Optimal Index of Refraction and is described as

For glass with ns around 15 in air (n0 around 10) then the optimum refractive index will be n1 =

1225

To reduce the refraction in this case we now mean the one that is produced inside the chamber of the

Laser diode the easiest way is to apply a low reflectivity AR coating on the surface of the laser To

measure the appropriate thickness of the coating layer we can use the equations described above By

applying a coat exactly

thickness film we can assure that a certain wavelength is transmitted The

27

reflected waves from the back of the glass medium will be half a wavelength out of phase So they

interfere destructively Because all reflected waves are interfered the maximum amount of light passes

through the coating Please refer to figure 2-15 to illustrate this idea

Fig 2-15 Light Passing through AR Coat and Glass

The most common process to attain this final product is by vacuum deposition For the best coating

results we need to lower the pressure inside the vacuum system to torr

Fig 2-16 Lens without (Top) and With (Bottom) AR Coating

28

233 Laser Diode Basic Principles

A laser diode is a laser whose active medium is a semiconductor similar to that found in

light-emitting diodes (LEDs) Please refer to figure 2-17 The most common type of laser diode is formed

from a p-n junction and powered by injected electric current

Fig 2-17 Laser Diode

Laser diodes are formed by doping a very thin layer on the surface of a crystal wafer The crystal is

doped to produce the n-type region and a p-type region one above the other

By referring to figure 1-2 we can see the basic structure of a working laser When the laser diode has

a current passing through it the light will get excited inside its gain medium and then will start to

resonate this process is called pumping The current exceeds the critical current and then it comes out as

laser light Please refer to figure 1-3 Since we use an external cavity laser we need to apply the AR

coating to the diode and adjust a diffraction grating The laser light comes out the diode and bounces on

the grating making the resonance externally and this becomes the ldquocavityrdquo as shown in figure 2-18

Fig 2-18 Tunable Laser Basic Configuration

29

The most important feature of the external cavity laser is that we can adjust the wavelength easily just

by changing the diffraction gratingrsquos angle and in the end this is the output wavelength of the laser For

different wavelengths there will be different levels of visible light as shown in figure 2-19

Fig 2-19 Light Spectrum

234 Quartz Microbalance System

A Quartz Crystal Microbalance is an instrument that measures a mass per unit area by measuring the

change in frequency of a quartz crystal resonator The resonance is disturbed by the addition or removal

of a small mass due to oxide growthdecay or film deposition (which is the case in our study) at the

surface of the acoustic resonator The QCM can be used under vacuum in gas phase and more recently in

liquid environments It is useful for monitoring the rate of deposition in thin film deposition systems

under vacuum Frequency measurements are easily made with high precision

For our research we used the Sigma Instruments SQM-160 RateThickness Monitor shown in figure

2-20

Fig 2-20 Front and Back Panels of SQM-160

30

The microbalance uses Quartz as the resonator Quartz is one member of the family of crystals that

experience the Piezoelectric Effect

Piezoelectricity is the charge that accumulates in certain solid materials in response to applied

mechanical stress It means electricity resulting from pressure It was discovered in 1880 by Jacques and

Pierre Curie It is understood as the linear electromechanical interaction between the mechanical and the

electrical state in crystalline materials with no inversion symmetry It is a reversible process in that

materials exhibiting direct piezoelectricity also exhibit the reverse This means that the internal generation

of electrical resulting from applied mechanical force and vice versa

By using the piezoelectric effect we can probe as an acoustic resonance by electrical means Applying

alternating current to the quartz crystal induces oscillations This creates a shear wave We can use these

qualities to determine the resonance frequency at high accuracy

The frequency of oscillation of the crystal is partially dependent in the thickness of the crystal During

normal operation all the variables are held constant so a change in thickness correlates directly to a

change in frequency As mass is deposited or etched away the thickness increases or decreases and so the

frequency of oscillation changes accordingly With some simplifying assumptions the frequency change

can be quantified and correlated precisely to the mass change using the Sauerbreyrsquos Equation

Developed by G Sauerbrey in 1959 it is a method for correlating changes in the oscillation

frequency of a piezoelectric crystal with the mass deposited on it It is defined as below

Where f0 is the Resonant frequency Δf is the Frequency change Δm is the mass change A is the

piezoelectrically active area of the crystal q is the Density of quartz (2648 gcmsup3) and μq is the Shear

modulus of quarts(2947x gcmssup2)

Because the film is treated as an extension of thickness Sauerbreyrsquos equation only applies to systems

in which the following 3 conditions are met

Deposited mass must be rigid

Deposited mass must be distributed evenly

The frequency change

lt002

If the change is greater than 2 the Z-match method must be used to determine the change in mass

It is defined as

Where fL is the frequency of the loaded crystal fU is the resonant frequency Nq is the frequency

constant (1668x HzAring) Δm is the mass change A is the piezoelectrically active area of the crystal

31

q is the density of quartz Z is the method constant f is the density of film μq Is the shear modulus of

quarts and μf is the shear modulus of film

The Sauerbrey equation cannot be applied to systems under liquid medium

The crystals are seed crystals plated with gold on both top and bottom for applications A crystal is

shown in figure 2-21 The QCM consists of a thin piezoelectric plate with electrodes evaporated on both

sides Due to the piezoelectric effect AC voltage across the electrodes induces a shear deformation and

vice versa The electromechanical coupling provides a simple way to detect an acoustic resonance by

electrical means

The Z also called Z-factor is a constant value for different materials and it is shown together with the

density of different materials in table 2-2 below

Fig 2-21 QCM Crystals

The Oscillator of the SQM-160 is shown in figure 2-22 and the equivalent circuit for the Resonant

Oscillator is shown in figure 2-23

Fig 2-22 SQM-160 Oscillator

32

Fig 2-23 Oscillator Circuit

33

Table 2-2 Z-Ratios for Different Materials

Table 2-2 Continued

34

Table 2-2 Continued

35

Table 2-2 Continued

36

Table 2-2 Continued

37

Table 2-2 Continued

38

Table 2-2 Continued

235 Vacuum Chamber System

Vacuum Evaporation is the process of depositing thin films of materials onto surfaces The technique

consists of pumping a vacuum chamber to pressures of less than torr and heating a material to

produce a flux of vapor in order to deposit the material onto a surface The material to be vaporized is

typically heated until its vapor pressure is high enough to produce a flux several Angstrom per second by

using an electrically resistive heater or bombardment by a high voltage beam The process was invented

by Henri Nestle in 1886 for food industry

In here the system has been pumped to a vacuum of Torr When a high current is passed

through the filament boat the filament boat is heated over the desired metal evaporation temperature and

so evaporation starts When the evaporation process is finished and the metal cools down crystals

condensate in the surface of the wafer From the weight of the evaporated material the distance between

the filament boat and the wafer we are able to calculate the deposition thickness and we can also use the

mass detector follower like the Quartz crystal resonator microbalance system In the process of

evaporation we usually use a board in between the filament boat and the wafer This is because before we

arrive to the desired evaporation temperature there will be some impurities that will be vaporized in the

controlled environment so we first use a small current and the board in between to get rid of those

impurities and this raises the purity of the deposition material

39

A vacuum evaporation system is shown in figure 2-24

Fig 2-24 Vacuum Evaporation System

Rough Vacuum 760 ~ 1 torr

Medium Vacuum 1 ~ torr

High Vacuum ~ torr

Ultra-High Vacuum Lower than torr

Table 2-3 Classification of Vacuum

For our study we need to use a Turbo Pump A regular turbo pump is shown in figure 2-25

Fig 2-25 Turbo Pump

For our research we used the Pfeiffer TCP 015 Electronic Drive Unit and Granville Phillips 375

Convectron shown below in figure 2-26

40

Fig 2-26 Control and Measurement Equipment

The electronic drive controls the turbo pump and the Convectron measures the pressure inside our

chamber The turbo pump is a type of vacuum pump used to maintain high vacuum Most turbo pumps

are centrifugal When we start the pumping we need to use a mechanical pump so as to decrease the

pressure inside the system from constant atmospheric pressure to torr and then the use dispersion

pump to continue the vacuum until we get to the desired pressure We need to notice though when we

start the dispersion pump we canrsquot turn off the mechanical pump and they both need to run together If

we need to turn off the pumping we first turn off the dispersion pump wait for it to completely stop and

then turn off the mechanical pump

Our completely assembled system is shown in figure 2-27 below

Fig 2-27 Complete System

41

Chapter 3 TENSILE TESTING IN DEPTH

31 Experimentrsquos Purpose and Principles

By means of Universal testing machine and Strain gauges we were able to observe discuss and

analyze the phenomena created when a specimen of certain material is manipulated under an external load

and determine the stress strain and deformation values later we can use the graphing methods of

stress-strain diagram to describe it

The main point of this experiment is that after the tensile specimen is tested use computer analysis

and the actual strain data and after statistical adjustment make the final results report (Tensile testing

experiment is in accordance with ASTM E8)

32 Experimentrsquos Equipment

321 Universal Testing Machine

For the materials testing experiment part of this research we use a Universal Testing Machine as

shown in figure 31 The maximum load it can apply is 100 Ton After the test specimen is secured on the

device with the use of instrumentation the load exerted and the effects of this become apparent on the

specimen and even the smallest of changes can be recorded For our research we used the Chun Yen

Testing Machines Co Ltd 100 Ton Micro Computer Universal Tensile Tester

Fig 31 Universal Testing Machine

42

Table 31 shows the specifications for this machine

Max Capacity 100 Ton

Accuracy plusmn1

Tension (mm) Max Space 1150mm

Grip for Rod 20-70mm

Ram Stroke 250mm

Effective Column Interval 940mm

Crosshead Speed 300mmmin

Testing Speed 0-50mmmin

Volume of Machine 1700times1000times3350mm(LtimesWtimesH)

Volume of Control Panel 1000times800times1500mm(LtimesWtimesH)

Weight 8000kg

Power 3∮220V 20A

Computer AMD K6-2-350

OS Windows XP

Screen 15rdquo CRT

Table 3-1 Chun Yen Testing Machine Specs Table

The connections diagram is shown in figure 3-2

Fig 3-2 Diagram for System Connections

43

When the test specimen is placed when the external force is applied the Load Cell can measure the

size of the applied force and the Encoder measures the expansion rate of change The Local Controller

receives all the information from the 2 units after arranging the results they are displayed in the

computer and they can be afterwards submitted for more complex analysis such as Finite Element

Analysis and we can get the Stress-Strain Diagram

322 Strain Measurement Equipment

The equipment used in our research provides a four-channel measurement that means we can use up

to 4 strain gauges at a time to do our measurements and provides 3 different bridge arrangements as

shown in figure 3-3

(a) (b) (c)

Fig 3-3 Input Connections for Strain Indicator

Figure 3-3 (a) is the Quarter Bridge (b) is the Half Bridge and (c) is the Full Bridge and Transducers

For our study we used the Quarter Bridge and use the Strain Gauge values to decide the position of the

connecting wires The Strain indicator is shown in figure 3-4

Fig 3-4 Vishay Micro-Measurements Model P3 Strain Indicator and Recorder

44

Input Connections Tool Free eccentric lever release

4-channel input

Wire diameter16-28AWG

Bridge Configurations Quarter- Half- and Full Bridge

Bridge Impedance 60-2000Ω

Display 128 64 pixel FSTN positive gray LCD

Data Conversion AD Converter filter

Measurement Range Resolution Strain Range plusmn155mVV

Resolution plusmn00005mVV

Measurement Accuracy plusmn01 of reading plusmn3 counts

Gage Factor Control 0500-9900

Balance Control Software either manual or automatic

Bridge Excitation 15VDC nominal

Communication Interface USB Cable Included

Data Storage Removable Media Card

Shunt Calibration Across bridge completion resistors controlled

by software When Gage Factor=200

120Ω350Ω1000Ω

Analog Output Value 0 to 25V max

Ranges plusmn320 microε plusmn3200 microε plusmn32000 microε

Error 05 output voltage +5mV

Max Error 14 output voltage + 20mV

Update rate 480 samplessec

Output Load 2000Ω

Power Battery Two Alkaline D cells

Battery life 400 hours typ

USB 5V 100mA

Operational Environment Temperature 0-50

Humidity Up to 90 Non-condensing

Case Aluminum Alloy

Size and Weight 228times152times152(mm) 20(kg)

Table 3-2 Vishay Micro-Measurements Model P3 Strain Indicator and Recorder Specs

45

323 Strain Gauge

The strain gaugersquos main basic principle is to use a resistancersquos characteristics to measure the strain

The inside connections of the strain indicator are shown in figure 3-5

Fig 3-5 Inner Connections

As shown above this is a quarter-bridge connection We connect equal-length 3 wires to the 2

connections allowed by the strain gauge wire 1 and 3 can be used to cancel out the effects of temperature

to the resistance and because of the addition of wires 1 and 3 wire 2 can directly measure the experiment

results from the strain gauge and therefore the strain developed with no influence of temperature

If there were no two measuring leads then the relations will be

R 4 =R g +2R L

Where Rg is the Strain Gauge Value and RL is the wire resistance then

4

4

R

R=

Lg

g

RR

R

2

=

gL

gg

RR

RR

21

amp

4

4

R

R=

g

g

R

R(1- L)

Where L is the Signal Loss Factor and so

L =gL

gL

RR

RR

21

2

g

L

R

2R if

g

L

R

2Rltlt1

46

(Actual Value R g =120R L =08g

L

R

2Ris always much smaller than 1)

R 4 =R g +2R LR 2 =R 3 =rR gR 1 =R g 32 RR =0

V 0 =V 2)1( r

r

(

4

4

R

R-

1

1

R

R)

The first term describes loss attenuation effects second term describes loss of balancing capabilities

effects

V 0 =V 2)1( r

r

[

)2

(Lg

g

RR

R

+

T

Lg

g

RR

R

)

2( + T

Lg

L

RR

R

)

2

2( -(

g

g

R

R) T ]

The first term describes loss attenuation effects and loss of balancing capabilities effects the second

third and fourth terms describe the temperature effects on the wire

For the three-wire method we have

L =gL

gL

RR

RR

1

g

L

R

R if

g

L

R

Rltlt1

V 0 =V 2)1( r

r

[

)(Lg

g

RR

R

+

T

Lg

g

RR

R

)( + T

Lg

L

RR

R

)

2( -

T

Lg

g

RR

R

)( - T

Lg

L

RR

R

)

2( ]

V 0 = V2)1( r

r

)(

Lg

g

RR

R

In the last four terms inside parenthesis we can see the effects of temperature being cancelled out and the

effect on first term is not great so this is the reason why in our research we use three wires

47

324 Specimen Measurements

The tensile specimens used in this research are compliant of ASTM E8 Tensile parameters as shown

in figure 3-6

Fig 3-6 Tensile Specimen

Diameter

D(mm)

Gauge

Length

G(mm)

Smallest

Arc

Radius

R(mm)

Shortest

Area

A(mm)

Total

Length

L(mm)

Clamping

Area

Length

B(mm)

Clamping

Area

Diameter

C(mm)

Bar 125 02 625 01 gt10 gt75 ~ 145 ~ 35 20

Table 3-3 Specifications for Round Bar

33 Experiment Procedure

1 Attaching the Strain Gauge to the Tensile Specimen

(1) Prepare 1 ASTM E8 compliant tensile specimen round bar as shown in figure 3-7

(2) Prepare Strain Gauge as those described in table 3-4

(3) Prepare other consumables and adhesive agent such as epoxy adhesive or

cyanoacrylate adhesive as shown in figure 3-8

48

Fig 3-7 Actual Tensile Specimen

Fig 3-8 Other Materials Used (Such as Alcohol gauze transparent tape adhesive)

Gage Type

EA-06-120LZ-120E

Resistance in ohms at 24∘C

1200plusmn03

Gage Factor at 24∘C

2075plusmn05

Transverse Sensitivity at 24∘C

(+07plusmn02)

Table 3-4 Specifications for Strain Gauge

2 Attaching Strain Gauge

As shown in following figures we shall explain the attachment of the strain gauge

(1) Use sand paper and a rasp to clean thoroughly the surface where the strain gauge will be

attached to

49

(a)

(2) Use alcohol to wash the surface where the strain gauge will be attached and use gauze to rub

it off

(b)

(3) Find a clean surface and clean it with alcohol and gauze

(c)

(4) Place the strain gauge in the clean surface Use a piece of transparent tape on top of the strain

gauge after securely placed rip it off the surface carefully

50

(d)

(5) Use a piece of white paper to mark the place where the strain gauge will be attached and in

this way we can make sure that the strain gauge will be placed as horizontally and vertically

correct as possible

(e)

(6) In the place where we had our mark place the strain gauge

(f)

(7) Carefully lift one side of the tape and apply some of the adhesive agent to both the strain

gauge and specimenrsquos surface

(g)

51

(8) We need to make sure that the gauge and the specimen will be firmly attached so we gently

apply pressure with our thumb

(h)

(9) After the adhesive is fully dry we can carefully rip off the tape

(i)

(10) We need to do the whole process twice one for the horizontally placed strain gauge and one

for the vertically placed strain gauge

52

(j)

(11) We now proceed to solder the wires to the strain gauge

(k)

(12) After soldering we use a Volt Multimeter to measure that there is no contact between wires

If there is none then the specimen is ready for testing

(l)

(13) We now need to measure a 5cm distance and mark it to check and compare the elongation

before and after the tensile testing

(m)

53

Fig 3-9 Specimen-Strain Gauge Process

3 Tensile Test

(1) Enter the computer application that controls the tensile testing machine

(2) Turn on the tensile testing machine main switch

(3) Adjust the hydraulic pump to go back to its original position

(4) Bring the lowering motor down to a distance enough so as to attach the tensile specimen to the

system open the clamps and secure the specimen

(a)

(5) Connect all the necessary wires to the strain indicator equipment

54

(b)

(6) Start the ascending motor and wait for the expansion

(c)

Fig 3-10 Specimen-Tensile Testing Process

4 Start the Test

(1) Enter the software application and enter some variables needed for the experiment in the

specific screen

(2) Go back to the main screen and press the [測試] (measure) button to start the test and auto

recording in the software

(3) After the specimen breaks the mechanical device will automatically stop and ask the user to

enter the total displacement We take out the specimen from the testing machine and adjust the

machinersquos position back to its original position

(4) Save the results information

(5) Record the results from the strain indicator

34 Results

From this experiment we can get the Poissonrsquos Ratio Youngrsquos Modulus and Yield Strength etc and

because of the slippage phenomenon in the clamp at the moment of the test then the Elastic Limit will

display some yield phenomena So omit any undesirable results we just take the Yield portion of the

results as reference

In the process of the experiment the most important part to attend to is the attaching of the strain

gauge because the gaugersquos purpose is to measure the strain developed during the test and this strain

might be very small If the gaugersquos angle change during the test ie is not well attached this will affect

the accuracy of the measurements of Poissonrsquos ratio and Youngrsquos modulus

55

The materials provided by the manufacturer are SUM 23 and SUM 43 steel round bars and these two

types of materials have been through different heat treatment processes so they can be sub-divided

further into untreated material heat-treated material and black surface heat treated material for the two

materials with heat treatment the treatment process and finished are different In the end we only have

the mechanical properties that were calculated after our research of these materials

All of the specifications are identical to those shown in figure 3-6

341 SUM 23

Fig 3-11 SUM 23 Untreated Material

Number 7 10

Hardness(HRB) 74 75

Yield Stress (MPa) 448 440

Tensile Strength (MPa) 544 560

Poissonrsquos Ratio 029 027

Youngrsquos Modulus (GPa) 203 210

Cut-off Area Shrinking () 42 41

Elongation () 1125 1011

Table 3-5 Mechanical Properties of SUM 23 Untreated

56

Stress-Strain Diagram

(a)

(b)

57

Fig 3-12 Stress-Strain Diagrams for (a) 7 Round Bar and (b) 10 Round Bar

Cut-Off Area

(a)

(b)

Fig 3-13 Cut-Off Area of (a) 7 Round Bar and (b) 10 Round Bar

58

SUM 23 Nickel Round Bar

Fig 3-14 SUM 23 Nickel Material

Number 1 2 3 4

Hardness(HRB) 48 50 49 48

Yield Stress (MPa) 370 370 380 400

Tensile Strength (MPa) 455 451 450 450

Poissonrsquos Ratio 028 046 029 026

Youngrsquos Modulus (GPa) 243 303 246 206

Cut-off Area Shrinking () 803 803 726 601

Elongation () 566 65 602 647

Table 3-6 Mechanical Properties of SUM 23 Nickel

59

Stress-Strain Diagram

(a)

60

(b)

(c)

(d)

61

Fig 3-15 Stress-Strain Diagrams for (a) 1 Round Bar (b) 2 Round Bar (c) 3 Round Bar and (d)

4 Round Bar

Cut-Off Area

(a)

(b)

62

(c)

(d)

Fig 3-16 Cut-Off Area of (a) 1 Round Bar (b) 2 Round Bar (c) 3 Round Bar and (d) 4 Round

Bar

63

SUM 23 Black Surface Round Bar

Fig 3-17 SUM 23 Black Surface Material

Number 1 2 3

Hardness(HRB) 51 50 51

Yield Stress (MPa) 378 371 369

Tensile Strength (MPa) 467 465 464

Poissonrsquos Ratio 03 016 04

Youngrsquos Modulus (GPa) 215 266 266

Cut-off Area Shrinking () 986 94 848

Elongation () 748 805 761

Table 3-7 Mechanical Properties of SUM 23 Black Surface Material

64

Stress-Strain Diagram

(a)

(b)

65

(c)

Fig 3-18 Stress-Strain Diagrams for (a) 1 Round Bar 2 Round Bar and (c) 3 Round Bar

Cut-Off Surface

(a)

66

(b)

(c)

Fig 3-19 Cut-Off Surface of (a) 1 Round Bar 2 Round Bar and (c) 3 Round Bar

67

342 SUM 43

Fig 3-20 Untreated SUM 43 Untreated Material

Number 1 5

Hardness(HRB) 76 75

Yield Stress (MPa) 572 594

Tensile Strength (MPa) 743 785

Poissonrsquos Ratio 027 029

Youngrsquos Modulus (GPa) 200 202

Cut-off Area Shrinking () 338 2944

Elongation () 857 894

Table 3-8 Mechanical Properties of SUM 43 Untreated

68

Stress-Strain Diagrams

(a)

(b)

Fig 3-21 Stress-Strain Diagrams for SUM 43 (a) 1 Round Bar and (b) 5 Round Bar

69

Cut-Off Area

(a)

(b)

Fig 3-22 Cut-Off Area of SUM 43 (a) 1 Round Bar and (b) 5 Round Bar

70

SUM 43 Nickel Round Bar

Fig 3-23 SUM 43 Nickel Material

Number 4 5

Hardness(HRB) 51 50

Yield Stress (MPa) 1580 1544

Tensile Strength (MPa) 1639 1625

Poissonrsquos Ratio 03 028

Youngrsquos Modulus (GPa) 194 201

Cut-off Area Shrinking () 1697 137

Elongation () 376 265

Table 3-9 Mechanical Properties of SUM 43 Nickel

71

Stress-Strain Diagrams

(a)

(b)

Fig 3-24 Stress-Strain Diagrams for (a) 4 Round Bar and (b) 5 Round Bar

72

Cut-Off Area

(a)

(b)

Fig 3-25 Cut-Off Area of (a) 4 Round Bar and (b) 5 Round Bar

73

SUM 43 Black Surface Material

Fig 3-26 SUM 43 Black Surface Material

Number 3 5

Hardness(HRB) 56 56

Yield Stress (MPa) 1416 1361

Tensile Strength (MPa) 1591 1402

Poissonrsquos Ratio 029 031

Youngrsquos Modulus (GPa) 200 202

Cut-off Area Shrinking () 139 124

Elongation () 24 24

Table 3-10 Mechanical Properties of SUM 43 Black Surface Material

74

Stress-Strain Diagrams

0 2 4 6 8 10 12 14

-200

0

200

400

600

800

1000

1200

1400

1600

1800

應力 (MPa)

應變()

(a)

0 2 4 6 8 10

-200

0

200

400

600

800

1000

1200

1400

1600

應力

(MPa)

位移 ()

(b)

Fig 3-27 Stress-Strain Diagrams for (a) 3 Round Bar and (b) 5 Round Bar

(Note These curves were formulated using Visual Solutions Inc VisSim Software)

75

Cut-Off Area

(a)

(b)

Fig 3-28 Cut-Off Area of (a) 3 Round Bar and (b) 5 Round Bar

76

The force value (N) was retrieved from the Universal Testing Machine

The Poissonrsquos Ratio (ε) is calculated as

ε =

the values for the Poissonrsquos Ratio are in average around 0297

The Youngrsquos Modulus (E) is calculated as

E =

Where

Stress =

Cross-sectional Area =

where D is the Diameter

The value for D was in average around 1258 mm

The values shown by the computer because there is Slippage phenomena between the Clamp and the

specimen will not be taken into consideration for the elongation strain and Youngrsquos modulus and we will

refer to the values that we have meticulously calculated

77

Chapter 4 AR COATING IN DEPTH

41 Experimentrsquos Purpose and Principles

By means of a vacuum chamber and several other instruments we intend to apply Anti-Reflective

Coating using deposition process to a laser diode and in this way reduce its refraction so as to make it

lose less light in the process of amplification and we can control certain wavelengths we want produced

for certain desired applications in our case we are attempting to re-create a Bose-Einstein Condensate

An optimal BEC apparatus is shown in figure 4-1

Fig 4-1 BEC Apparatus

The main point of this experiment is to build a vacuum chamber system attach all the instrumentation

needed (Vacuum pump deposition meter and voltmeter) and use it to apply AR coating to a laser diode

After we have accomplished the AR coating other team will be in charge of designing the BEC apparatus

and use the results of our research

78

42 Experimentrsquos Equipment

421 Vacuum Chamber

For this research we designed a vacuum chamber whose main body is shown in figure 4-2 Its

dimensions are

Width 240 mm

Length 240 mm

Height 200 mm

Outer Diameter 4 in

Inner Diameter 15 in

Fig 4-2 Vacuum Chamber Main Body

The chamber is made up of 6 pass ways pass way A is the connection with the Laser Deposition

Equipment pass way B is the connection with the Turbo Pump and pass way C is for the connection with

the Deposition Source

A

C

B

79

Pass way C is for the deposition source as mentioned above This is a system where a thermal

resistance is heated by passing a high current through it which heats up a filament boat (made of tungsten)

where the material to be evaporated is place We control the temperature as such that the material will

evaporate and the heat will not cause the filament boat to crack

Because P = Isup2 R (where P is power I is current and R is resistance) to avoid the current to flow

where it is not desired we decided that the material for the Thermocouple shown in figure 4-3 should be

Copper ᴓ 63 mm We choose it that way because Copper has very good heat dissipation characteristics

and the resistance value is low It can reduce the value of the current enough to make the thermocouple to

create heat

Fig 4-3 Thermocouple

To the thermocouple we attach the tungsten filament boat We need to take notice of materials to be

used in this design because when using high current the tungsten filament boar will heat up and so the

material must be able to keep up with the heating potential of tungsten and has a low coefficient of heat

dissipation to avoid the tungsten to fail when heating up and therefore not evaporating Considering all

this we decide to use Stainless Steel

Because this clamp will be assembled inside the chamber after many revisions it was determined it

will have the shape shown in figure 4-4

Fig 4-4 Filament Boat Clamp Design

80

For the tungsten filament boat we bought the product from a distributor The dimensions are

Length 100 mm

Width 10 mm

Height 1 mm

Our thermocouple is 15 in but the pass way C is 4 in so we need to attach a Flange that connects

15in to 4in Because these specifications are quite difficult to achieve by Milling we had to use

electrical wire cutting

For the laser clamping system where the laser that is going to be AR coated will be placed will be

connected to pass way A the assembly is shown in figure 4-5 below

Fig 4-5 Cover Assembly

For this design we used an O-ring instead of a gasket so as to save time The design of the assembly

where the laser will be placed is shown in figure 4-6

Fig 4-6 Upper Cover Inner Assembly

D

E

F

81

Point D is the plate in the assembly where the laser diode will be fixed Because of the easy

processing we decide to use Aluminum and it is screwed to the top cover Point E is the connection for

the Quartz crystal resonator and it is designed in the same as point F in this way the results of the quartz

microbalance system will be more accurate in real time Point F is the final resting place for the laser

diode We use a Thor Labs Base with dimensions of ᴓ 9mm and ᴓ 56mm for two different size laser

diodes It just needs to be plugged in for easy installation

From figure 4-6 we know that the system needs signal system connections and because of the

change in temperature inside the chamber this could affect the functioning of the quartz microbalance so

we also need to install water tubes for cooling This is shown in figure 4-7 below

Fig 4-7 Diagram of Upper Cover Connections

In figure 4-8 we show the Feed through connections and their functions

Fig 4-8 Feed through Diagram

82

1 SQM-160 wire 5 Laser Connection 1 (Vin)

2 SQM-160 (G) 6 Laser Connection 2 (G)

3 K-Type-1 7 Laser Connection 3 (PD)

4 K-Type-2 8 Not In Use

The fully assembled chamber is shown in figure 4-9

Fig 4-9 Fully Assembled Chamber

422 Quartz Crystal Microbalance

For measuring the deposition on our target for coating we used the Inficon SQM-160 RateThickness

Monitor It is an easy to use instrument for measuring many types of thin-film coatings as shown in

figure 4-10

(a) Front Panel (b) Back Panel

Fig 4-10 Inficon SQM-160

83

Table 4-1 shows the technical specifications for this equipment

Number of sensors 2 Standard 4 additional optional

Sensor Frequency Range 40 MHz ~ 60 MHz

Reference Frequency Accuracy 002

Thickness Display Resolution 1 Aring

Thickness Resolution 015 Aring (Std) 0037 Aring (Hi Res)

Density of Stored Films 05-9999 gmcc

Tooling 10-399

Z-Factor 010-1000

Final Thickness 0000-9999k Aring

Measurement Period 15 to 2 sec

Simulation Mode Yes

Frequency Mode Yes

Rate Resolution 011 Arings

Dual Crystal Yes

Etch Mode Yes

Crystal Tooling 10-399

Crystal Fail Min Max 40 to 60 MHz 41 to 61 MHz

Power 100-120 200-240~plusmn10 nominal 20W

Operation Environment 0degC ~ 50degC

0 ~ 80 RH non-condensing

0 ~ 2000 meters

Class 1 Equipment

Pollution Degree 2

Rack Dimensions 885mm x 2127mm x 1969mm

Weight 27 kg

Table 4-1 Inficon SQM-160 RateThickness Monitor Specs

84

To the SQM-160 we need to connect an Oscillator We use the Sigma Instruments Remote Oscillator

Ser No 2 268 as shown in figure 4-11

Fig 4-11 Sigma Instruments Remote Oscillator

The connections diagram is shown in figure 4-12

Fig 4-12 SQM-160 Connections Diagram

85

423 Turbo Pump

For our experiments we used the Pfeiffer TCP 015 Electronic Drive Unit shown below in figure 4-13

Table 4-2 shows the technical specifications for this equipment

(a) Front Panel (b) Back Panel

Fig 4-13 Pfeiffer TCP 015 Electronic Drive

Connection Voltage (100V) 90-112

Mains Frequency 5060 Hz

Start-up Current 22 A

Nominal Frequency 1500 Hz

Rotation Speed 10V = 1500Hz plusmn2

Analog Output Current 10 V = 25 A plusmn 5

Rotation Speed Switchpoint 750 Hz

Works Setting 8 min

Permissible Ambient Temperature 0degC ~ 40degC

Dimensions Front Panel 1285mm x 1063mm

Insertion Length 227mm

Weight 27 Kg

Table 4-2 Pfeiffer TCP 015 Electronic Drive Specs

86

The connections diagram is shown in figure 4-14

Fig 4-14Connections Diagram for Pfeiffer TCP 015

To measure the pressure inside the chamber we use the Granville Phillips 375 Convectron Vacuum

Pressure Controller shown in figure 4-15

(a) Front Panel (b) Back Panel

Fig 4-15 Granville Phillips 375 Convectron

87

Its dimensions are shown in figure 4-16

Fig 4-16 Dimensions of Convectron

Table 4-3 shows the technical specifications for this equipment

Table 4-3 Granville Phillips 375 Convectron Vacuum Pressure Controller Specs

88

424 Multimeter

For our experiment we used the Keithley 2000 Digital Multimeter as shown in figure 4-17

(a) Front Panel (b) Back Panel

Fig 4-17 Keithley Model 2000 6-12-Digit Digital Multimeter

Its technical specifications are shown in table 4-4

Table 4-4 Keithley Model 2000 6-12-Digit Digital Multimeter Specs

89

43 Experiment Procedure

1 Connecting together the equipment and the chamber

(1) We first connect the resonator to the thickness monitor and connect the other side to the

chamber

(2) We now connect the flexible tubes to the turbo pump on one side and to the chamber on the

other

(3) We need to check that tubes are tightly connected to avoid any leaks in the vacuum pumping

process which will not allow us to get to our goal of Torr As shown in figure 4-18

(4) Connect the convectron to the system as shown in figure 4-19

Fig 4-18 checking for leaks using alcohol

Fig 4-19 Convectron attached to System

90

(5) Attach the clamps of the Multimeter to the bottom of the chamber as shown in figure 4-20

(6) Place the Quartz crystal in place

(7) Close tight vacuum chamber

(8) Connect all electrical appliances to power source

Fig 4-20 Multimeter Connections

2 Starting up the System

(1) We turn on all the devices as such Check all systems are ready to function Reset all values

that might be left over from previous tests

(2) Start the thickness monitor and set all values for this experiment In our case we got to testing

the system but not actual coating So we used the simulation mode of the thickness monitor as

shown in figure 4-21

Fig 4-21 Simulation Mode

91

(3) Start the turbo pump Make sure the lid on the vacuum chamber is tightly closed

(4) Start convectron and record initial pressure

(5) Start Multimeter and record initial current

3 Coating Process

(1) If we have the deposition material inside the filament boat the power source for the high

current must be started as well

(2) Record all initial values for thickness current pressure

(3) For an ideal experiment we need a thickness of around 101 nm a pressure of Torr and

a current of 300 A

44 Results

From previous experiments we have shown that we can turn a LED into a laser by means of AR

Coating In figure 4-22 shown below we can compare the actual results of a Diode before and after AR

coating From the blue line we can see that when the diode is at a current of 15mA its light will change

from LED to laser and if we look at the red line its critical current is around 30 to 35 mA

Fig 4-22 AR Coating Comparison for Laser Diodes

This means that the light emitted is not as strong as if the diode had been coated because inside the

chamber there must be some excitation first so the reflectivity of both sides inside the diode must be high

So because of the coating in one of the sides we have opened a door and let the light come out so the

critical current is risen as such and will be higher value than that of before the coating

92

In the following figures we can see the difference between before and after coating in a material The

thickness is around 1016 nm for this material

Fig 4-23 Before Coating

Fig 4-24 After Coating

93

Chapter 5 CONCLUSIONS AND RECOMMENDATIONS

51 Conclusions

For the first part of this independent study taking into consideration the data that came out of our

research and that sent by the provider we can say

1 SUM 23 after heat treatment will unexpectedly develop cracking in the middle of the tensile

testing process and suddenly break

2 Itrsquos possible that in the process of heat treatment to the SUM 23 material the treatment was not

uniform and this will create a pre-loaded moment force on one side that pushes on the other side

of the specimen resulting in material deformation

3 In the process of attaching the strain gauges to the materials it is very easy to make errors due to

poor adhesion or sudden removal in the tensile testing process

For our second part of the independent study the following can be made

1 At the beginning of this independent study we had no idea what Bose-Einstein Condensate was

or what was its purpose After much literature we finally comprehended the basic principles to

put into practice for our research

2 Our systemrsquos basic working principles and equipmentrsquos complexity are a little difficult to grasp

but hopefully we were able to understand enough of it

3 Theoretically from relation between the power and current we can know the advantages and

disadvantages of AR Coating

4 We were able to assemble the system and run test on its functions Even though we were able to

do this there is still much more work left to do with this system

52 Recommendations

For the Tensile Testing the following can be said

1 Ask the provider to check on the process of heat treatment on the SUM 23 material and give

them the information we have gathered through our test so they can correct for the mechanical

properties found if any change is needed

2 To avoid the problem of the inaccuracy of the poor adhesion of strain gauges we can attach

multiple strain gauges to the same one specimen so as to correlate data and improve our results

For the AR Coating the following can be said

1 We need to make sure that there are no physical defects on the main body of the chamber so as to

achieve maximum efficiency in the vacuum process If there was then the vacuum will arrive to

certain point and then start to decrease

2 It would be preferable to add some sort of visual aid that will allow the user to check the inside of

the chamber without actually opening it This will help us determine at what times we should

manipulate the current to better evaporate the substrate

94

REFERENCES

[1] A L Window Strain Gauge Technology Elsevier Applied Science London and New York 2nd

Edition 1992

[2] CC Perry and HR Lissner Strain Gauge Primer McGraw-Hill Book Co Inc New York 1955

[3] James W Dally William F Riley McGraw-Hill 1978

[4] University of Colorado Boulder BEC - What is it and where did the idea come from

httpwwwcoloradoeduphysics2000becwhat_is_ithtml

[5] Ultraslow Light amp Bose-Einstein Condensates Two-way Control with Coherent Light amp Atom

Fields Harvard Hau Lab Dr Lene Vestergaard Hau Optics amp Photonics News 16 1995

[6] The Art of Taming Light Ultra-slow and Stopped Light Harvard Hau Lab Dr Lene

Vestergaard Hau Europhysics News 2004

[7] Nonlinear Optics Shocking Superfluids Harvard Hau Lab Dr Lene Vestergaard Hau Nature

Physics 2007

[8] Model P3 Strain Indicator and Recorder Instruction Manual Vishay Micro-Measurements 2005

[9] Granville-Phillips Series 375 Convectron Vacuum Gauge Controller Instruction Manual Brooks

Automation 2008

[10] Effect of Film Thickness on the Validity of the Sauerbrey Equation for Hydrated Polyelectrolyte

Films Vogt Lin Wu White 2004

[11] Quartz Crystal Microbalance Study of DNA Immobilization and Hybridization for DNA Sensor

Development Chang Zhao 2008

[12] Installation of Strain Gages with SR-4 PrecoatAdhesive Vishay Micro-Measurements 2005

[13] Strain Gauge Measurement ndash A Tutorial National Instruments 1998

[14] Correlation between Vickers Hardness Number and Yield Stress of Cold-Formed Products

Yavuz Tekkaya

[15] httpsenwikipediaorg

Page 11: PC Hinge Materials Testing and AR Laser Diode Coating

11

We wish to investigate the properties of Anti Reflecting Coating on laser diodes Hopefully

we will be able to achieve the desired effect of reducing the surface reflection coefficient and

find applications for it

12 Research Objective

We wish to analyze the normal composition of the notebook computerrsquos hinge at which

point in the assembly is clearly the weakest and at this time in the assembly the strength and

durability are influenced The main point is to see if we can affect the normal operation and work

life

The objective of this thesis is to present the results of the material properties under tensile

testing find the mechanical properties and after using finite element analysis determine what

material is the best for our purposes

Fig 1-1 Notebook Computer Hinge

For our second research we wish to produce and analyze laser diodes with anti-reflective

coating and test its properties and applications

When semi-conductor laser has been submitted to current it will produce resonance inside it

and light will be stimulated to come out Please refer to figure 1-2 for the basic structure of a

laser

Fig 1-2 Basic Structure of a Laser

1 Gain Medium

2 Laser Pumping Energy

3 High Reflector

4 Output Coupler

5 Laser Beam

12

But when the laser diode generates light but the laser diode canrsquot produce light on itself it

must wait for the current to be higher than certain value which is called the critical current Until

the light goes over this threshold then it is considered laser light if not it is just considered as a

common LED light source Please refer to figure 1-3

Fig 1-3 Comparison between LED and Laser Diode

As we can see from figure 1-3 all of the light that goes over the critical current is laser light

and so the external cavity semi-conductor laser that we built needs Anti-Reflective Coating

because the method we want to use needs an external cavity laser that has been covered with AR

Coating and a Diffraction Grating We use this configuration first by shooting the laser to the

grating and this will be shot back to the laser creating the external resonance cavity which is

shown in figure 1-4

Fig 1-4 External Cavity Design

13

Two configurations are shown the Littrow Configuration and the Littman-Metcalf

Configuration The Littrow configuration contains a collimating lens and a diffraction grating as

the end mirror The first order diffracted beam provides optical feedback to the laser diode which

has AR Coating The emission wavelength can be turned by rotating the diffraction grating A

disadvantage is that it also changes the direction of the output beam

In the Littman-Metcalf configuration the grating orientation is fixed and an additional mirror

is used to reflect the first order beam back to the laser diode The wavelength can be turned by

rotating that mirror This configuration offers a fixed direction of the output beam and also tends

to exhibit smaller line width as the wavelength selectivity is stronger A disadvantage is that

zero order reflection of the beam reflected by the tuning mirror is lost so that the output power is

less than that of a Littrow laser

13 Methodology

The aim of this research is to find the mechanical properties of materials after being

subjected to tensile testing through finite element analysis observations and determine what

material is best for our purposes taking into consideration the strength and durability of the

material among other properties to find use and applications for the AR coated laser diodes to

further improve the grasp of the Bose-Einstein condensation working principles

14 Organization of the Thesis

The research paper includes five chapters

1 Chapter 1 explains the motivation background objective and methodology of this study

2 Chapter 2 explains the working principles and basic knowledge needed to understand this

study

3 Chapter 3 explains the tensile testing in detail steps methods and results

4 Chapter 4 explains the AR coating in detail steps methods and results

5 Chapter 5 is the conclusions taken from the results shown in chapter 3 and 4 and

recommendations done after arranging and critical thinking

14

Chapter 2 BASICS THEORIES

21 Tensile Testing

After a specimen is tested with the use of tensile testing we can get the Stress-Strain Curve using the

relation between tension and displacement Typical curves are shown in Fig 2-1

(a) Ductile materials (b) Brittle materials

Fig 2-1 Stress-Strain Curve

The curve is unique for each material and is found by recording the amount of deformation at distinct

intervals of tensile or compressive loads Thanks to the use of the Stress-Strain curve we can get very

useful information such as

211 Youngrsquos Modulus (E)

As shown in Fig 2-1 as long as the external load is not greater than the Proportional Limit the Stress

(σ) and Strain (ε) remain as a linear relation fulfilling Hookersquos Law

σ = Eε

The slope is the constant factor the inverse of the modulus of elasticity E also called Youngrsquos

modulus When the external load goes over the proportional limit the stress-strain relationship doesnrsquot

follow the linear relation anymore but the deformation remains flexible When the load is released the

deformation is completely eliminated and the specimen goes back to its original state This is called

15

Elastic Deformation When the external load goes over the Elastic limit only then does the specimen

presents Plastic Deformation This type of deformation which is irreversible even when the load is

removed comes after the material does under elastic deformation so this means the object will first come

part way to its original shape Common metals and ceramics have roughly the same elastic limits

212 Yield Strength and Yield Point

Some materials display very evident yield phenomena while some materials donrsquot as shown in Fig

2-2 After we exceed the elastic limit if we continue to exert load when we arrive to a certain value

which differs under different materials and external conditions there is sudden decrease in stress and this

is called the Yield Strength and can be defined as the stress at which a material begins to deform

plastically using the equation

σyield =

Where P is the tension force and Ao is the original cut-off area

The stress remain at a certain value after the decrease but the strain increases this phenomena can be

easily appreciated when studying the behavior of common Carbon Steel Fig2-2 (a) but most metals (like

Aluminum Copper or High Steel Carbon) donrsquot display this kind of behavior as shown in Fig 2-2 (b)

Arriving to this point is very difficult and the most commonly used method for this is to add a 02 or

0002 offset yield strength to the curve This point is held constant on the strain axis of the curve and

from the 0002 position we draw a straight line parallel to the linear relationship line the point at where

this line and the stress-strain curve intercept is the point we take as the 02 offset yield strength

(a)Evident (b) Non-evident

Fig2-2 Stress-Strain Curve Comparison on Metals

16

213 Ultimate Tensile Strength and Breaking Strength

After materials undergo yield they keep lending strength and hardening phenomena occurs (work

hardening) on the material and the external load increases When it has reached the highest point this is

called the Ultimate Tensile Strength (UTS) as shown in Fig2-1 The UTS is defined as

σUTS =

Where Pmax is the load at the materialrsquos ultimate tensile strength point and Ao is the original cut-off

area For brittle materials the ultimate tensile strength is the most important mechanical property for

ductile materials the ultimate tensile strength is not commonly used for industrial and designing purposes

because upon arriving to this value the material already has forgone great plastic deformation After the

specimen goes through UTS there will be necking phenomena which is a mode of tensile deformation

where relatively large amounts of strain localize disproportionately in a small region of the material It

results from instability during tensile deformation when a materialrsquos cross-sectional area decreases by a

greater proportion than the material strain hardens The specimen continues to elongate until it finally

breaks and the load at this point is called Breaking Strength The breaking strength is defined as the

greatest stress in tension that a material is capable of withstanding without rupture

Where Pf is the load at the materialrsquos breaking strength point and Ao is the original cut-off area

214 Poissonrsquos Ratio (ν)

For elastic deformation when materials are compressed in one direction they tend to expand in the

other two directions perpendicular to the direction of compression This is called the Poissonrsquos Effect

The Poison Ratio is a measure of the Poissonrsquos effect It is the ratio of the fraction of expansion divided

by the fraction of compression for small values of these changes

ν=-

215 Strain Gauge Basic Principles

The strain gauge is a device used to measure the strain of an object Itrsquos an elongated metal resistor

which is attached to the specimen being measured and when the specimen is under strain and starts to

deform the strain gauge will have a change in the resistance With the change in value we can calculate

the elementrsquos strain or elastic modulus and the Poissonrsquos ratio

It takes advantage of the physical property of electrical conductance and its dependence on the

conductorrsquos geometry When the electrical conductor (the specimen being tested) is stretched within the

limits of elasticity such that it does not break or deform plastically it will become narrower and longer

17

which increases the electrical resistance through-out From the measured resistance of the strain gauge

the amount of stress may be inferred by using the relations

R=

Where R is the original resistance value is the electrical resistivity lo is the original length of the

conductor and Ao is the original cross sectional area of the conductor If after the application of tension

the change in length is Δl let the length of the specimen be l = l + Δlo and the tension is the same

through-out So

And the resistance is

The Gauge Factor is the ratio of relative change in electrical resistance to the mechanical strain in

other words it is the relative change in length It is defined as

The strain gauge was invented in 1938 by Edward E Simmons and Arthur C Ruge and the most

common type consists of an insulating flexible backing which supports a metallic foil usually made of a

brass-nickel alloy It is attached to the specimen by a suitable adhesive As the object is deformed the foil

also deforms and this causes the electrical resistance to change Then this is usually measured using a

Wheatstone bridge shown below and is related to the strain by the Gauge Factor

Fig2-3 Basic Structure of Strain Gauge

18

Fig 2-4 Strain gauge attached to Wheatstone bridge

22 Hardness Testing Basic Principles

221 Brinell Scale BHN

The Brinell Scale characterizes the indentation hardness of materials through the scale of penetration

of an indenter loaded on a material specimen The typical test uses a 10mm diameter steel ball as indenter

(usually of value equal to BHN450) with a 29kN force For softer materials smaller force is used The

indentation is measured and BHN is calculated using the relation

BHN =

radic

Where F is the applied force usually within the range of 100 250 500 750 1000 1500 2000 2500

and 3000 kgf D is the diameter of indenter usually within the range of 5mm or 10mm plusmn0005 margin

and d is the diameter of indentation usually around 2mm Its units are of Kgmmsup2 but are not normally

written

First proposed by Swedish engineer Johan August Brinell in 1900 it was the first widely used and

standardized hardness test in engineering and metallurgy although the large size of indentation and

possible damage to specimen limits its usefulness

Fig 2-5 Brinell Indentation Fig2-6 Brinell Hardness Tester

19

222 Rockwell Scale HR

The Rockwell scale is a hardness scale based on the indentation hardness of a material The Rockwell

test determines the hardness by measuring the depth of penetration of an indenter under a large load

compared to the penetration made by a preload The indenter is forced into the specimen under a

preliminary load When equilibrium is reached a measuring device follows the movements of the

indenter and responds to changes in depth of penetration of the indenter While the preload is still being

applied additional major load is applied resulting in increased penetration When equilibrium is reached

again the major load is removed but the preload is maintained Removing the major load allows partial

recovery and reduces the depth of penetration The permanent increase in depth of penetration resulting

from the application and removal of the major load is used to calculate the Rockwell number using the

relation

HR = E ndash e

Where E is a constant depending on the form of the indenter 100 units for diamond indenter and 130

units for steel ball indenter e is the permanent increase in depth of penetration due to the major load

measured in units of 0002mm

Fig 2-7 Rockwell Indentation

When testing materials indentation hardness is related linearly to the tensile strength The important

relation permits economically important nondestructive testing of bulk metal deliveries with lightweight

equipment like the Rockwell tester shown below in figure 2-7

Fig 2-8 Rockwell Hardness Tester

20

There are different scales denoted by a single letter that use different loads or different indenters

The result is a dimensionless number denoted as HR X where X will be the letter denoting the scale as

shown below in table 2-1

Table 2-1 Rockwell Hardness Test Scale

Differential depth hardness measurement was first conceived in 1908 by Viennese professor Paul

Ludwik It eliminated the errors associated with the mechanical imperfections of the system such as

backlash and surface imperfections in the specimen Rockwell testing has an advantage over Brinell

testing because the latter was slow itrsquos not useful on fully hardened steel and left too large an impression

to be considered nondestructive

The tester was co-invented by Hugh M Rockwell and Stanley P Rockwell The requirement for this

tester was to quickly determine the effects of heat treatment on steel bearing races

21

223 Vickers Hardness Test HV

This is a type of microindentation hardness test where a diamond indenter of specific geometry is

impressed into the surface of the test specimen using a known applied force ranging from 10 to 1000

grams This type of tests usually has forces of 2N and produce indentations of about 50μm They can be

used to observe changes in hardness on the microscopic scale It is difficult to standardize the

microhardness measurements because it has been found that the microhardness of almost any material is

higher than its macrohardness The values also vary with load and work-hardening effects of materials

The Vickers test is often easier to use than other hardness tests because the required calculations are

independent of the size of the indenter and the indenter can be used for all materials It can be used for all

metals and has one of the widest scales among hardness tests The unit of the Vickers test is denoted as

HV and can be converted to units of Pascal (Pa) but it is not a measurement of pressure The hardness

number is determined by the load over the surface area of the indentation and not the area normal to the

force

A square-based pyramid shaped diamond is use as the indenter It has been established that the ideal

size of a Brinell impression was 38 of the ball diameter As two tangents to the circle at the ends of a

chord 3d8 long intersect at 136plusmn05deg it was decided to use this as the angle of the indenter giving an

angle to the horizontal plane of 22deg on each side The HV number is determined by the ratio FA where F

is the force applied to the diamond in kgf and A is the surface area of the resulting indentation in mmsup2 A

can be determined by the relation

A =

Where A is the surface area of indentation and d is the average length diagonal left by the indenter

This can be approximated as

A =

Then the Vickers Number is

HV =

=

Vickers hardness number is reported as xxxHVyy or xxxHVyyzz (if duration of applied force differs

from 10s to 15s) where xxx are replaced by the hardness number yy is the load in kg and zz indicates

loading time The values are generally independent of test force

The test was developed in 1921 by Robert L Smith and George E Sandland at Vickers Ltd as an

alternative to Brinell method to measure the hardness of materials

22

Fig 2-9 Vickers Indentation Fig 2-10 Vickers Hardness Tester

23 AR Coating

231 Bose-Einstein Condensate

The Bose-Einstein Condensate or BEC is a state of matter of a dilute gas of bosons cooled to

temperatures very near absolute zero around 0K or -27315degC Under such conditions a large fraction of

the bosons occupy the lowest quantum state where the quantum effects become apparent on a

macroscopic scale This gave birth to the Bose-Einstein Statistics which are the rules that govern the

behavior at this state It is one of the two possible ways in which a collection of indistinguishable particles

may occupy a set of available discrete energy states The aggregation of particles in the same state

accounts for the cohesive streaming of laser light and the frictionless creeping of superfluid helium (an

application discussed later) Bose and Einstein recognized that a collection of identical and

indistinguishable particles can be distributed this way This theory applies only to those particles not

limited to single occupancy of the same state particles that do not obey the Pauli Exclusion Principle

restrictions Such particles are the Bosons named after the statistics that correctly describe their behavior

This phenomenon was first predicted by Satyendra Nath Bose around 1924 when he considered how

groups of photons behave He then asked Albert Einstein for help publishing his discoveries to which

Einstein agreed and gave follow up supporting these findings The resulting efforts became the concept of

a Bose gas governed by the Bose-Einstein Statistics described above Einstein demonstrated that cooling

bosonic atoms to a very low temperature would cause them to condense into the lowest accessible

quantum state resulting in a new form of matter

The first gaseous condensate we produced by Eric Cornell and Carl Wieman at the University of

Colorado at Boulder NIST ndash JILA lab sung a gas of rubidium atoms cooled to 170 nK which earned

them the 2001 Nobel Prize in physics together with Wolfgang Ketterle from MIT The transition to BEC

occurs below a critical temperature which for a uniform three dimensional gas consisting of

non-interacting particles with no apparent internal degrees of freedom is given by

23

Tc =

(

)

asymp 33125

Where Tc is the critical temperature n is the particle density m is the mass per boson h is the

reduced Planck constant k is the Boltzmann constant and ζ is the Riemann zeta function

There are two classes of elementary particles defined by whether their quantum spin is a nonnegative

integer or an odd half integer A Bose-Einstein Condensate is shown below in figure 2-11

Fig 2-11 Bose Einstein Condensate at different scales

Bosons are the particles whose quantum spin is a nonnegative integer (s = 0 1 2 etc) Examples of

bosons include fundamental particles (Higgs Boson Photons W and Z Bosons Gluons Gravitons etc)

composite particles (Mesons Hadrons Nuclei and Atoms of Carbon-12 and Helium-4) and

quasi-particles Bosons are considered force carrier particles The Bosons differ from Fermions in that

there is no limit to the number that can occupy the same quantum state This is called the Pauli Exclusion

Principle

The Pauli Exclusion Principle says that no two identical fermions may occupy the same quantum state

simultaneously in other words this means that the total wave function for two identical fermions is

anti-symmetric with respect to exchange of the particles This means that no two electrons in a single

atom can have the same four quantum numbers

Fermion is any particle characterized by Fermi-Dirac Statistics and follows the Pauli Exclusion

Principle described above Quarks Leptons and composite particles (Hadrons Nuclei and Atoms of

Carbon-13 and Helium-3) made of an odd number of these are considered Fermions It can be an

elementary particle such as the electron or a composite particle such as the protons Following the Pauli

24

Exclusion Principle only one fermion can occupy a particular quantum state at any given time If multiple

fermions have the same spatial probability distribution then at least one property of each fermion must be

different Fermions are usually associated with matter because composite fermions are key building

blocks of matter (neutrons and protons)

Fermionsrsquo behavior by the Fermi-Dirac Statistics which describes the energies of single particles in a

system comprising of many identical particles It applies to identical particles with half-odd integer spin

in a system of thermal equilibrium The particles in the system are assumed to have negligible mutual

interaction This allows the many-particle system to be described in terms of single-particle energy states

The result is the Fermi-Dirac distribution of particles over these states and includes the condition that no

two particles can occupy the same state which has considerable effect on the properties of the system

In quantum mechanics the position of an object is uncertain An object has a definite probability of

being at any given point in space This probability is encoded in the wave function mentioned earlier If

one concentrates a large number of identical bosons in a small region then it is possible for their wave

functions to overlap so much that the bosons lose their identity When this happens thatrsquos a Bose-Einstein

Condensate It is only possible at very low temperatures because at high temperatures the individual

bosons have small wave functions and move rapidly which causes them to fly apart

For now applications are still restricted because there are still some setbacks regarding BECs They

are extremely fragile they are being produced in small quantities with just a few million atoms at a time

and finally they can only be made from certain types of atoms Some examples are the atom laser Ketterle

in which a conventional light lase emits a beam of coherent photons this means they are all in phase and

can be concentrated to an extremely small bright spot BECs can slow down light as demonstrated by

Prof Lene Hau PhD in 2001 by the use of a superfluid [7] These manipulations could develop into

new types of telecommunications technology optical storage and quantum computing

BECs are related to super-fluidity and super-conductivity Super-fluidity is the state of matter in

which the behavior is that of a fluid with zero viscosity It was discovered in liquid helium but now it has

applications in astrophysics high-energy physics and theories of quantum gravity

Super-conductivity is a phenomenon of exactly zero electrical resistance and expulsion of magnetic

fields occurring in certain materials when cooled below a characteristic critical temperature A

super-conductor is shown below in figure 2-12

Fig2-12 Super Conductor

25

232 AR Coating Basic Principles

Anti-reflective (AR) coating is a type of optical coating applied to the surface of lenses and other

optical devices (in our case we planned to apply it to a laser diode) to reduce reflection This improves

the efficiency of the system since less light is lost The primary benefit is the elimination of the reflection

itself

When light the medium (glass) it will produce reflection if 100 of the light comes from the air and

enters the glass because therersquos a difference between the index of refraction some of the light will go out

and when the light is coming out of the glass into the air once again because of the difference between

index of refraction some of the light wonrsquot be able to pass through the medium

When the light makes the first trip into the glass there was a loss of about 4 in the reflection and

when the light makes the trip back outside there was another loss of about 4 so when we assume that

100 of the light interacts with the medium actually therersquos just about 92 acting (we neglect the light

absorbed by the glass around 05) To illustrate this idea please refer to figure 2-13

Fig 2-13 Simple Model for Light in Glass Medium

When we apply the AR Coating the light that enters will only have a loss of about 05 and when

making the trip back outside again only 05 of light is loss so we get the result of increasing the light

passing through up to 99 (again neglecting the light absorbed by the glass around 05) To illustrate

this idea please refer to figure 2-14

26

Fig 2-14 Simple Model for Light in Glass Medium after AR Coating

The AR Coating can reduce reflection of incoming light In the case that light hits perpendicular to

the surface of the medium the intensity of the reflection can be calculated using the Reflection

Coefficient

Where n0 and ns are the refractive indices of the first and second media respectively The value of R

varies from 0 (no reflection) to 1 (all light reflected) and is usually quoted as a percentage

Complementary to R is the transmission coefficient or Transmittance If absorption and scattering are

neglected then the value of Transmittance is always 1-R then if a beam of light with intensity I is

incident on the surface a beam of intensity RI is reflected and a beam with intensity TI is transmitted to

the medium

The optimal value is called the Optimal Index of Refraction and is described as

For glass with ns around 15 in air (n0 around 10) then the optimum refractive index will be n1 =

1225

To reduce the refraction in this case we now mean the one that is produced inside the chamber of the

Laser diode the easiest way is to apply a low reflectivity AR coating on the surface of the laser To

measure the appropriate thickness of the coating layer we can use the equations described above By

applying a coat exactly

thickness film we can assure that a certain wavelength is transmitted The

27

reflected waves from the back of the glass medium will be half a wavelength out of phase So they

interfere destructively Because all reflected waves are interfered the maximum amount of light passes

through the coating Please refer to figure 2-15 to illustrate this idea

Fig 2-15 Light Passing through AR Coat and Glass

The most common process to attain this final product is by vacuum deposition For the best coating

results we need to lower the pressure inside the vacuum system to torr

Fig 2-16 Lens without (Top) and With (Bottom) AR Coating

28

233 Laser Diode Basic Principles

A laser diode is a laser whose active medium is a semiconductor similar to that found in

light-emitting diodes (LEDs) Please refer to figure 2-17 The most common type of laser diode is formed

from a p-n junction and powered by injected electric current

Fig 2-17 Laser Diode

Laser diodes are formed by doping a very thin layer on the surface of a crystal wafer The crystal is

doped to produce the n-type region and a p-type region one above the other

By referring to figure 1-2 we can see the basic structure of a working laser When the laser diode has

a current passing through it the light will get excited inside its gain medium and then will start to

resonate this process is called pumping The current exceeds the critical current and then it comes out as

laser light Please refer to figure 1-3 Since we use an external cavity laser we need to apply the AR

coating to the diode and adjust a diffraction grating The laser light comes out the diode and bounces on

the grating making the resonance externally and this becomes the ldquocavityrdquo as shown in figure 2-18

Fig 2-18 Tunable Laser Basic Configuration

29

The most important feature of the external cavity laser is that we can adjust the wavelength easily just

by changing the diffraction gratingrsquos angle and in the end this is the output wavelength of the laser For

different wavelengths there will be different levels of visible light as shown in figure 2-19

Fig 2-19 Light Spectrum

234 Quartz Microbalance System

A Quartz Crystal Microbalance is an instrument that measures a mass per unit area by measuring the

change in frequency of a quartz crystal resonator The resonance is disturbed by the addition or removal

of a small mass due to oxide growthdecay or film deposition (which is the case in our study) at the

surface of the acoustic resonator The QCM can be used under vacuum in gas phase and more recently in

liquid environments It is useful for monitoring the rate of deposition in thin film deposition systems

under vacuum Frequency measurements are easily made with high precision

For our research we used the Sigma Instruments SQM-160 RateThickness Monitor shown in figure

2-20

Fig 2-20 Front and Back Panels of SQM-160

30

The microbalance uses Quartz as the resonator Quartz is one member of the family of crystals that

experience the Piezoelectric Effect

Piezoelectricity is the charge that accumulates in certain solid materials in response to applied

mechanical stress It means electricity resulting from pressure It was discovered in 1880 by Jacques and

Pierre Curie It is understood as the linear electromechanical interaction between the mechanical and the

electrical state in crystalline materials with no inversion symmetry It is a reversible process in that

materials exhibiting direct piezoelectricity also exhibit the reverse This means that the internal generation

of electrical resulting from applied mechanical force and vice versa

By using the piezoelectric effect we can probe as an acoustic resonance by electrical means Applying

alternating current to the quartz crystal induces oscillations This creates a shear wave We can use these

qualities to determine the resonance frequency at high accuracy

The frequency of oscillation of the crystal is partially dependent in the thickness of the crystal During

normal operation all the variables are held constant so a change in thickness correlates directly to a

change in frequency As mass is deposited or etched away the thickness increases or decreases and so the

frequency of oscillation changes accordingly With some simplifying assumptions the frequency change

can be quantified and correlated precisely to the mass change using the Sauerbreyrsquos Equation

Developed by G Sauerbrey in 1959 it is a method for correlating changes in the oscillation

frequency of a piezoelectric crystal with the mass deposited on it It is defined as below

Where f0 is the Resonant frequency Δf is the Frequency change Δm is the mass change A is the

piezoelectrically active area of the crystal q is the Density of quartz (2648 gcmsup3) and μq is the Shear

modulus of quarts(2947x gcmssup2)

Because the film is treated as an extension of thickness Sauerbreyrsquos equation only applies to systems

in which the following 3 conditions are met

Deposited mass must be rigid

Deposited mass must be distributed evenly

The frequency change

lt002

If the change is greater than 2 the Z-match method must be used to determine the change in mass

It is defined as

Where fL is the frequency of the loaded crystal fU is the resonant frequency Nq is the frequency

constant (1668x HzAring) Δm is the mass change A is the piezoelectrically active area of the crystal

31

q is the density of quartz Z is the method constant f is the density of film μq Is the shear modulus of

quarts and μf is the shear modulus of film

The Sauerbrey equation cannot be applied to systems under liquid medium

The crystals are seed crystals plated with gold on both top and bottom for applications A crystal is

shown in figure 2-21 The QCM consists of a thin piezoelectric plate with electrodes evaporated on both

sides Due to the piezoelectric effect AC voltage across the electrodes induces a shear deformation and

vice versa The electromechanical coupling provides a simple way to detect an acoustic resonance by

electrical means

The Z also called Z-factor is a constant value for different materials and it is shown together with the

density of different materials in table 2-2 below

Fig 2-21 QCM Crystals

The Oscillator of the SQM-160 is shown in figure 2-22 and the equivalent circuit for the Resonant

Oscillator is shown in figure 2-23

Fig 2-22 SQM-160 Oscillator

32

Fig 2-23 Oscillator Circuit

33

Table 2-2 Z-Ratios for Different Materials

Table 2-2 Continued

34

Table 2-2 Continued

35

Table 2-2 Continued

36

Table 2-2 Continued

37

Table 2-2 Continued

38

Table 2-2 Continued

235 Vacuum Chamber System

Vacuum Evaporation is the process of depositing thin films of materials onto surfaces The technique

consists of pumping a vacuum chamber to pressures of less than torr and heating a material to

produce a flux of vapor in order to deposit the material onto a surface The material to be vaporized is

typically heated until its vapor pressure is high enough to produce a flux several Angstrom per second by

using an electrically resistive heater or bombardment by a high voltage beam The process was invented

by Henri Nestle in 1886 for food industry

In here the system has been pumped to a vacuum of Torr When a high current is passed

through the filament boat the filament boat is heated over the desired metal evaporation temperature and

so evaporation starts When the evaporation process is finished and the metal cools down crystals

condensate in the surface of the wafer From the weight of the evaporated material the distance between

the filament boat and the wafer we are able to calculate the deposition thickness and we can also use the

mass detector follower like the Quartz crystal resonator microbalance system In the process of

evaporation we usually use a board in between the filament boat and the wafer This is because before we

arrive to the desired evaporation temperature there will be some impurities that will be vaporized in the

controlled environment so we first use a small current and the board in between to get rid of those

impurities and this raises the purity of the deposition material

39

A vacuum evaporation system is shown in figure 2-24

Fig 2-24 Vacuum Evaporation System

Rough Vacuum 760 ~ 1 torr

Medium Vacuum 1 ~ torr

High Vacuum ~ torr

Ultra-High Vacuum Lower than torr

Table 2-3 Classification of Vacuum

For our study we need to use a Turbo Pump A regular turbo pump is shown in figure 2-25

Fig 2-25 Turbo Pump

For our research we used the Pfeiffer TCP 015 Electronic Drive Unit and Granville Phillips 375

Convectron shown below in figure 2-26

40

Fig 2-26 Control and Measurement Equipment

The electronic drive controls the turbo pump and the Convectron measures the pressure inside our

chamber The turbo pump is a type of vacuum pump used to maintain high vacuum Most turbo pumps

are centrifugal When we start the pumping we need to use a mechanical pump so as to decrease the

pressure inside the system from constant atmospheric pressure to torr and then the use dispersion

pump to continue the vacuum until we get to the desired pressure We need to notice though when we

start the dispersion pump we canrsquot turn off the mechanical pump and they both need to run together If

we need to turn off the pumping we first turn off the dispersion pump wait for it to completely stop and

then turn off the mechanical pump

Our completely assembled system is shown in figure 2-27 below

Fig 2-27 Complete System

41

Chapter 3 TENSILE TESTING IN DEPTH

31 Experimentrsquos Purpose and Principles

By means of Universal testing machine and Strain gauges we were able to observe discuss and

analyze the phenomena created when a specimen of certain material is manipulated under an external load

and determine the stress strain and deformation values later we can use the graphing methods of

stress-strain diagram to describe it

The main point of this experiment is that after the tensile specimen is tested use computer analysis

and the actual strain data and after statistical adjustment make the final results report (Tensile testing

experiment is in accordance with ASTM E8)

32 Experimentrsquos Equipment

321 Universal Testing Machine

For the materials testing experiment part of this research we use a Universal Testing Machine as

shown in figure 31 The maximum load it can apply is 100 Ton After the test specimen is secured on the

device with the use of instrumentation the load exerted and the effects of this become apparent on the

specimen and even the smallest of changes can be recorded For our research we used the Chun Yen

Testing Machines Co Ltd 100 Ton Micro Computer Universal Tensile Tester

Fig 31 Universal Testing Machine

42

Table 31 shows the specifications for this machine

Max Capacity 100 Ton

Accuracy plusmn1

Tension (mm) Max Space 1150mm

Grip for Rod 20-70mm

Ram Stroke 250mm

Effective Column Interval 940mm

Crosshead Speed 300mmmin

Testing Speed 0-50mmmin

Volume of Machine 1700times1000times3350mm(LtimesWtimesH)

Volume of Control Panel 1000times800times1500mm(LtimesWtimesH)

Weight 8000kg

Power 3∮220V 20A

Computer AMD K6-2-350

OS Windows XP

Screen 15rdquo CRT

Table 3-1 Chun Yen Testing Machine Specs Table

The connections diagram is shown in figure 3-2

Fig 3-2 Diagram for System Connections

43

When the test specimen is placed when the external force is applied the Load Cell can measure the

size of the applied force and the Encoder measures the expansion rate of change The Local Controller

receives all the information from the 2 units after arranging the results they are displayed in the

computer and they can be afterwards submitted for more complex analysis such as Finite Element

Analysis and we can get the Stress-Strain Diagram

322 Strain Measurement Equipment

The equipment used in our research provides a four-channel measurement that means we can use up

to 4 strain gauges at a time to do our measurements and provides 3 different bridge arrangements as

shown in figure 3-3

(a) (b) (c)

Fig 3-3 Input Connections for Strain Indicator

Figure 3-3 (a) is the Quarter Bridge (b) is the Half Bridge and (c) is the Full Bridge and Transducers

For our study we used the Quarter Bridge and use the Strain Gauge values to decide the position of the

connecting wires The Strain indicator is shown in figure 3-4

Fig 3-4 Vishay Micro-Measurements Model P3 Strain Indicator and Recorder

44

Input Connections Tool Free eccentric lever release

4-channel input

Wire diameter16-28AWG

Bridge Configurations Quarter- Half- and Full Bridge

Bridge Impedance 60-2000Ω

Display 128 64 pixel FSTN positive gray LCD

Data Conversion AD Converter filter

Measurement Range Resolution Strain Range plusmn155mVV

Resolution plusmn00005mVV

Measurement Accuracy plusmn01 of reading plusmn3 counts

Gage Factor Control 0500-9900

Balance Control Software either manual or automatic

Bridge Excitation 15VDC nominal

Communication Interface USB Cable Included

Data Storage Removable Media Card

Shunt Calibration Across bridge completion resistors controlled

by software When Gage Factor=200

120Ω350Ω1000Ω

Analog Output Value 0 to 25V max

Ranges plusmn320 microε plusmn3200 microε plusmn32000 microε

Error 05 output voltage +5mV

Max Error 14 output voltage + 20mV

Update rate 480 samplessec

Output Load 2000Ω

Power Battery Two Alkaline D cells

Battery life 400 hours typ

USB 5V 100mA

Operational Environment Temperature 0-50

Humidity Up to 90 Non-condensing

Case Aluminum Alloy

Size and Weight 228times152times152(mm) 20(kg)

Table 3-2 Vishay Micro-Measurements Model P3 Strain Indicator and Recorder Specs

45

323 Strain Gauge

The strain gaugersquos main basic principle is to use a resistancersquos characteristics to measure the strain

The inside connections of the strain indicator are shown in figure 3-5

Fig 3-5 Inner Connections

As shown above this is a quarter-bridge connection We connect equal-length 3 wires to the 2

connections allowed by the strain gauge wire 1 and 3 can be used to cancel out the effects of temperature

to the resistance and because of the addition of wires 1 and 3 wire 2 can directly measure the experiment

results from the strain gauge and therefore the strain developed with no influence of temperature

If there were no two measuring leads then the relations will be

R 4 =R g +2R L

Where Rg is the Strain Gauge Value and RL is the wire resistance then

4

4

R

R=

Lg

g

RR

R

2

=

gL

gg

RR

RR

21

amp

4

4

R

R=

g

g

R

R(1- L)

Where L is the Signal Loss Factor and so

L =gL

gL

RR

RR

21

2

g

L

R

2R if

g

L

R

2Rltlt1

46

(Actual Value R g =120R L =08g

L

R

2Ris always much smaller than 1)

R 4 =R g +2R LR 2 =R 3 =rR gR 1 =R g 32 RR =0

V 0 =V 2)1( r

r

(

4

4

R

R-

1

1

R

R)

The first term describes loss attenuation effects second term describes loss of balancing capabilities

effects

V 0 =V 2)1( r

r

[

)2

(Lg

g

RR

R

+

T

Lg

g

RR

R

)

2( + T

Lg

L

RR

R

)

2

2( -(

g

g

R

R) T ]

The first term describes loss attenuation effects and loss of balancing capabilities effects the second

third and fourth terms describe the temperature effects on the wire

For the three-wire method we have

L =gL

gL

RR

RR

1

g

L

R

R if

g

L

R

Rltlt1

V 0 =V 2)1( r

r

[

)(Lg

g

RR

R

+

T

Lg

g

RR

R

)( + T

Lg

L

RR

R

)

2( -

T

Lg

g

RR

R

)( - T

Lg

L

RR

R

)

2( ]

V 0 = V2)1( r

r

)(

Lg

g

RR

R

In the last four terms inside parenthesis we can see the effects of temperature being cancelled out and the

effect on first term is not great so this is the reason why in our research we use three wires

47

324 Specimen Measurements

The tensile specimens used in this research are compliant of ASTM E8 Tensile parameters as shown

in figure 3-6

Fig 3-6 Tensile Specimen

Diameter

D(mm)

Gauge

Length

G(mm)

Smallest

Arc

Radius

R(mm)

Shortest

Area

A(mm)

Total

Length

L(mm)

Clamping

Area

Length

B(mm)

Clamping

Area

Diameter

C(mm)

Bar 125 02 625 01 gt10 gt75 ~ 145 ~ 35 20

Table 3-3 Specifications for Round Bar

33 Experiment Procedure

1 Attaching the Strain Gauge to the Tensile Specimen

(1) Prepare 1 ASTM E8 compliant tensile specimen round bar as shown in figure 3-7

(2) Prepare Strain Gauge as those described in table 3-4

(3) Prepare other consumables and adhesive agent such as epoxy adhesive or

cyanoacrylate adhesive as shown in figure 3-8

48

Fig 3-7 Actual Tensile Specimen

Fig 3-8 Other Materials Used (Such as Alcohol gauze transparent tape adhesive)

Gage Type

EA-06-120LZ-120E

Resistance in ohms at 24∘C

1200plusmn03

Gage Factor at 24∘C

2075plusmn05

Transverse Sensitivity at 24∘C

(+07plusmn02)

Table 3-4 Specifications for Strain Gauge

2 Attaching Strain Gauge

As shown in following figures we shall explain the attachment of the strain gauge

(1) Use sand paper and a rasp to clean thoroughly the surface where the strain gauge will be

attached to

49

(a)

(2) Use alcohol to wash the surface where the strain gauge will be attached and use gauze to rub

it off

(b)

(3) Find a clean surface and clean it with alcohol and gauze

(c)

(4) Place the strain gauge in the clean surface Use a piece of transparent tape on top of the strain

gauge after securely placed rip it off the surface carefully

50

(d)

(5) Use a piece of white paper to mark the place where the strain gauge will be attached and in

this way we can make sure that the strain gauge will be placed as horizontally and vertically

correct as possible

(e)

(6) In the place where we had our mark place the strain gauge

(f)

(7) Carefully lift one side of the tape and apply some of the adhesive agent to both the strain

gauge and specimenrsquos surface

(g)

51

(8) We need to make sure that the gauge and the specimen will be firmly attached so we gently

apply pressure with our thumb

(h)

(9) After the adhesive is fully dry we can carefully rip off the tape

(i)

(10) We need to do the whole process twice one for the horizontally placed strain gauge and one

for the vertically placed strain gauge

52

(j)

(11) We now proceed to solder the wires to the strain gauge

(k)

(12) After soldering we use a Volt Multimeter to measure that there is no contact between wires

If there is none then the specimen is ready for testing

(l)

(13) We now need to measure a 5cm distance and mark it to check and compare the elongation

before and after the tensile testing

(m)

53

Fig 3-9 Specimen-Strain Gauge Process

3 Tensile Test

(1) Enter the computer application that controls the tensile testing machine

(2) Turn on the tensile testing machine main switch

(3) Adjust the hydraulic pump to go back to its original position

(4) Bring the lowering motor down to a distance enough so as to attach the tensile specimen to the

system open the clamps and secure the specimen

(a)

(5) Connect all the necessary wires to the strain indicator equipment

54

(b)

(6) Start the ascending motor and wait for the expansion

(c)

Fig 3-10 Specimen-Tensile Testing Process

4 Start the Test

(1) Enter the software application and enter some variables needed for the experiment in the

specific screen

(2) Go back to the main screen and press the [測試] (measure) button to start the test and auto

recording in the software

(3) After the specimen breaks the mechanical device will automatically stop and ask the user to

enter the total displacement We take out the specimen from the testing machine and adjust the

machinersquos position back to its original position

(4) Save the results information

(5) Record the results from the strain indicator

34 Results

From this experiment we can get the Poissonrsquos Ratio Youngrsquos Modulus and Yield Strength etc and

because of the slippage phenomenon in the clamp at the moment of the test then the Elastic Limit will

display some yield phenomena So omit any undesirable results we just take the Yield portion of the

results as reference

In the process of the experiment the most important part to attend to is the attaching of the strain

gauge because the gaugersquos purpose is to measure the strain developed during the test and this strain

might be very small If the gaugersquos angle change during the test ie is not well attached this will affect

the accuracy of the measurements of Poissonrsquos ratio and Youngrsquos modulus

55

The materials provided by the manufacturer are SUM 23 and SUM 43 steel round bars and these two

types of materials have been through different heat treatment processes so they can be sub-divided

further into untreated material heat-treated material and black surface heat treated material for the two

materials with heat treatment the treatment process and finished are different In the end we only have

the mechanical properties that were calculated after our research of these materials

All of the specifications are identical to those shown in figure 3-6

341 SUM 23

Fig 3-11 SUM 23 Untreated Material

Number 7 10

Hardness(HRB) 74 75

Yield Stress (MPa) 448 440

Tensile Strength (MPa) 544 560

Poissonrsquos Ratio 029 027

Youngrsquos Modulus (GPa) 203 210

Cut-off Area Shrinking () 42 41

Elongation () 1125 1011

Table 3-5 Mechanical Properties of SUM 23 Untreated

56

Stress-Strain Diagram

(a)

(b)

57

Fig 3-12 Stress-Strain Diagrams for (a) 7 Round Bar and (b) 10 Round Bar

Cut-Off Area

(a)

(b)

Fig 3-13 Cut-Off Area of (a) 7 Round Bar and (b) 10 Round Bar

58

SUM 23 Nickel Round Bar

Fig 3-14 SUM 23 Nickel Material

Number 1 2 3 4

Hardness(HRB) 48 50 49 48

Yield Stress (MPa) 370 370 380 400

Tensile Strength (MPa) 455 451 450 450

Poissonrsquos Ratio 028 046 029 026

Youngrsquos Modulus (GPa) 243 303 246 206

Cut-off Area Shrinking () 803 803 726 601

Elongation () 566 65 602 647

Table 3-6 Mechanical Properties of SUM 23 Nickel

59

Stress-Strain Diagram

(a)

60

(b)

(c)

(d)

61

Fig 3-15 Stress-Strain Diagrams for (a) 1 Round Bar (b) 2 Round Bar (c) 3 Round Bar and (d)

4 Round Bar

Cut-Off Area

(a)

(b)

62

(c)

(d)

Fig 3-16 Cut-Off Area of (a) 1 Round Bar (b) 2 Round Bar (c) 3 Round Bar and (d) 4 Round

Bar

63

SUM 23 Black Surface Round Bar

Fig 3-17 SUM 23 Black Surface Material

Number 1 2 3

Hardness(HRB) 51 50 51

Yield Stress (MPa) 378 371 369

Tensile Strength (MPa) 467 465 464

Poissonrsquos Ratio 03 016 04

Youngrsquos Modulus (GPa) 215 266 266

Cut-off Area Shrinking () 986 94 848

Elongation () 748 805 761

Table 3-7 Mechanical Properties of SUM 23 Black Surface Material

64

Stress-Strain Diagram

(a)

(b)

65

(c)

Fig 3-18 Stress-Strain Diagrams for (a) 1 Round Bar 2 Round Bar and (c) 3 Round Bar

Cut-Off Surface

(a)

66

(b)

(c)

Fig 3-19 Cut-Off Surface of (a) 1 Round Bar 2 Round Bar and (c) 3 Round Bar

67

342 SUM 43

Fig 3-20 Untreated SUM 43 Untreated Material

Number 1 5

Hardness(HRB) 76 75

Yield Stress (MPa) 572 594

Tensile Strength (MPa) 743 785

Poissonrsquos Ratio 027 029

Youngrsquos Modulus (GPa) 200 202

Cut-off Area Shrinking () 338 2944

Elongation () 857 894

Table 3-8 Mechanical Properties of SUM 43 Untreated

68

Stress-Strain Diagrams

(a)

(b)

Fig 3-21 Stress-Strain Diagrams for SUM 43 (a) 1 Round Bar and (b) 5 Round Bar

69

Cut-Off Area

(a)

(b)

Fig 3-22 Cut-Off Area of SUM 43 (a) 1 Round Bar and (b) 5 Round Bar

70

SUM 43 Nickel Round Bar

Fig 3-23 SUM 43 Nickel Material

Number 4 5

Hardness(HRB) 51 50

Yield Stress (MPa) 1580 1544

Tensile Strength (MPa) 1639 1625

Poissonrsquos Ratio 03 028

Youngrsquos Modulus (GPa) 194 201

Cut-off Area Shrinking () 1697 137

Elongation () 376 265

Table 3-9 Mechanical Properties of SUM 43 Nickel

71

Stress-Strain Diagrams

(a)

(b)

Fig 3-24 Stress-Strain Diagrams for (a) 4 Round Bar and (b) 5 Round Bar

72

Cut-Off Area

(a)

(b)

Fig 3-25 Cut-Off Area of (a) 4 Round Bar and (b) 5 Round Bar

73

SUM 43 Black Surface Material

Fig 3-26 SUM 43 Black Surface Material

Number 3 5

Hardness(HRB) 56 56

Yield Stress (MPa) 1416 1361

Tensile Strength (MPa) 1591 1402

Poissonrsquos Ratio 029 031

Youngrsquos Modulus (GPa) 200 202

Cut-off Area Shrinking () 139 124

Elongation () 24 24

Table 3-10 Mechanical Properties of SUM 43 Black Surface Material

74

Stress-Strain Diagrams

0 2 4 6 8 10 12 14

-200

0

200

400

600

800

1000

1200

1400

1600

1800

應力 (MPa)

應變()

(a)

0 2 4 6 8 10

-200

0

200

400

600

800

1000

1200

1400

1600

應力

(MPa)

位移 ()

(b)

Fig 3-27 Stress-Strain Diagrams for (a) 3 Round Bar and (b) 5 Round Bar

(Note These curves were formulated using Visual Solutions Inc VisSim Software)

75

Cut-Off Area

(a)

(b)

Fig 3-28 Cut-Off Area of (a) 3 Round Bar and (b) 5 Round Bar

76

The force value (N) was retrieved from the Universal Testing Machine

The Poissonrsquos Ratio (ε) is calculated as

ε =

the values for the Poissonrsquos Ratio are in average around 0297

The Youngrsquos Modulus (E) is calculated as

E =

Where

Stress =

Cross-sectional Area =

where D is the Diameter

The value for D was in average around 1258 mm

The values shown by the computer because there is Slippage phenomena between the Clamp and the

specimen will not be taken into consideration for the elongation strain and Youngrsquos modulus and we will

refer to the values that we have meticulously calculated

77

Chapter 4 AR COATING IN DEPTH

41 Experimentrsquos Purpose and Principles

By means of a vacuum chamber and several other instruments we intend to apply Anti-Reflective

Coating using deposition process to a laser diode and in this way reduce its refraction so as to make it

lose less light in the process of amplification and we can control certain wavelengths we want produced

for certain desired applications in our case we are attempting to re-create a Bose-Einstein Condensate

An optimal BEC apparatus is shown in figure 4-1

Fig 4-1 BEC Apparatus

The main point of this experiment is to build a vacuum chamber system attach all the instrumentation

needed (Vacuum pump deposition meter and voltmeter) and use it to apply AR coating to a laser diode

After we have accomplished the AR coating other team will be in charge of designing the BEC apparatus

and use the results of our research

78

42 Experimentrsquos Equipment

421 Vacuum Chamber

For this research we designed a vacuum chamber whose main body is shown in figure 4-2 Its

dimensions are

Width 240 mm

Length 240 mm

Height 200 mm

Outer Diameter 4 in

Inner Diameter 15 in

Fig 4-2 Vacuum Chamber Main Body

The chamber is made up of 6 pass ways pass way A is the connection with the Laser Deposition

Equipment pass way B is the connection with the Turbo Pump and pass way C is for the connection with

the Deposition Source

A

C

B

79

Pass way C is for the deposition source as mentioned above This is a system where a thermal

resistance is heated by passing a high current through it which heats up a filament boat (made of tungsten)

where the material to be evaporated is place We control the temperature as such that the material will

evaporate and the heat will not cause the filament boat to crack

Because P = Isup2 R (where P is power I is current and R is resistance) to avoid the current to flow

where it is not desired we decided that the material for the Thermocouple shown in figure 4-3 should be

Copper ᴓ 63 mm We choose it that way because Copper has very good heat dissipation characteristics

and the resistance value is low It can reduce the value of the current enough to make the thermocouple to

create heat

Fig 4-3 Thermocouple

To the thermocouple we attach the tungsten filament boat We need to take notice of materials to be

used in this design because when using high current the tungsten filament boar will heat up and so the

material must be able to keep up with the heating potential of tungsten and has a low coefficient of heat

dissipation to avoid the tungsten to fail when heating up and therefore not evaporating Considering all

this we decide to use Stainless Steel

Because this clamp will be assembled inside the chamber after many revisions it was determined it

will have the shape shown in figure 4-4

Fig 4-4 Filament Boat Clamp Design

80

For the tungsten filament boat we bought the product from a distributor The dimensions are

Length 100 mm

Width 10 mm

Height 1 mm

Our thermocouple is 15 in but the pass way C is 4 in so we need to attach a Flange that connects

15in to 4in Because these specifications are quite difficult to achieve by Milling we had to use

electrical wire cutting

For the laser clamping system where the laser that is going to be AR coated will be placed will be

connected to pass way A the assembly is shown in figure 4-5 below

Fig 4-5 Cover Assembly

For this design we used an O-ring instead of a gasket so as to save time The design of the assembly

where the laser will be placed is shown in figure 4-6

Fig 4-6 Upper Cover Inner Assembly

D

E

F

81

Point D is the plate in the assembly where the laser diode will be fixed Because of the easy

processing we decide to use Aluminum and it is screwed to the top cover Point E is the connection for

the Quartz crystal resonator and it is designed in the same as point F in this way the results of the quartz

microbalance system will be more accurate in real time Point F is the final resting place for the laser

diode We use a Thor Labs Base with dimensions of ᴓ 9mm and ᴓ 56mm for two different size laser

diodes It just needs to be plugged in for easy installation

From figure 4-6 we know that the system needs signal system connections and because of the

change in temperature inside the chamber this could affect the functioning of the quartz microbalance so

we also need to install water tubes for cooling This is shown in figure 4-7 below

Fig 4-7 Diagram of Upper Cover Connections

In figure 4-8 we show the Feed through connections and their functions

Fig 4-8 Feed through Diagram

82

1 SQM-160 wire 5 Laser Connection 1 (Vin)

2 SQM-160 (G) 6 Laser Connection 2 (G)

3 K-Type-1 7 Laser Connection 3 (PD)

4 K-Type-2 8 Not In Use

The fully assembled chamber is shown in figure 4-9

Fig 4-9 Fully Assembled Chamber

422 Quartz Crystal Microbalance

For measuring the deposition on our target for coating we used the Inficon SQM-160 RateThickness

Monitor It is an easy to use instrument for measuring many types of thin-film coatings as shown in

figure 4-10

(a) Front Panel (b) Back Panel

Fig 4-10 Inficon SQM-160

83

Table 4-1 shows the technical specifications for this equipment

Number of sensors 2 Standard 4 additional optional

Sensor Frequency Range 40 MHz ~ 60 MHz

Reference Frequency Accuracy 002

Thickness Display Resolution 1 Aring

Thickness Resolution 015 Aring (Std) 0037 Aring (Hi Res)

Density of Stored Films 05-9999 gmcc

Tooling 10-399

Z-Factor 010-1000

Final Thickness 0000-9999k Aring

Measurement Period 15 to 2 sec

Simulation Mode Yes

Frequency Mode Yes

Rate Resolution 011 Arings

Dual Crystal Yes

Etch Mode Yes

Crystal Tooling 10-399

Crystal Fail Min Max 40 to 60 MHz 41 to 61 MHz

Power 100-120 200-240~plusmn10 nominal 20W

Operation Environment 0degC ~ 50degC

0 ~ 80 RH non-condensing

0 ~ 2000 meters

Class 1 Equipment

Pollution Degree 2

Rack Dimensions 885mm x 2127mm x 1969mm

Weight 27 kg

Table 4-1 Inficon SQM-160 RateThickness Monitor Specs

84

To the SQM-160 we need to connect an Oscillator We use the Sigma Instruments Remote Oscillator

Ser No 2 268 as shown in figure 4-11

Fig 4-11 Sigma Instruments Remote Oscillator

The connections diagram is shown in figure 4-12

Fig 4-12 SQM-160 Connections Diagram

85

423 Turbo Pump

For our experiments we used the Pfeiffer TCP 015 Electronic Drive Unit shown below in figure 4-13

Table 4-2 shows the technical specifications for this equipment

(a) Front Panel (b) Back Panel

Fig 4-13 Pfeiffer TCP 015 Electronic Drive

Connection Voltage (100V) 90-112

Mains Frequency 5060 Hz

Start-up Current 22 A

Nominal Frequency 1500 Hz

Rotation Speed 10V = 1500Hz plusmn2

Analog Output Current 10 V = 25 A plusmn 5

Rotation Speed Switchpoint 750 Hz

Works Setting 8 min

Permissible Ambient Temperature 0degC ~ 40degC

Dimensions Front Panel 1285mm x 1063mm

Insertion Length 227mm

Weight 27 Kg

Table 4-2 Pfeiffer TCP 015 Electronic Drive Specs

86

The connections diagram is shown in figure 4-14

Fig 4-14Connections Diagram for Pfeiffer TCP 015

To measure the pressure inside the chamber we use the Granville Phillips 375 Convectron Vacuum

Pressure Controller shown in figure 4-15

(a) Front Panel (b) Back Panel

Fig 4-15 Granville Phillips 375 Convectron

87

Its dimensions are shown in figure 4-16

Fig 4-16 Dimensions of Convectron

Table 4-3 shows the technical specifications for this equipment

Table 4-3 Granville Phillips 375 Convectron Vacuum Pressure Controller Specs

88

424 Multimeter

For our experiment we used the Keithley 2000 Digital Multimeter as shown in figure 4-17

(a) Front Panel (b) Back Panel

Fig 4-17 Keithley Model 2000 6-12-Digit Digital Multimeter

Its technical specifications are shown in table 4-4

Table 4-4 Keithley Model 2000 6-12-Digit Digital Multimeter Specs

89

43 Experiment Procedure

1 Connecting together the equipment and the chamber

(1) We first connect the resonator to the thickness monitor and connect the other side to the

chamber

(2) We now connect the flexible tubes to the turbo pump on one side and to the chamber on the

other

(3) We need to check that tubes are tightly connected to avoid any leaks in the vacuum pumping

process which will not allow us to get to our goal of Torr As shown in figure 4-18

(4) Connect the convectron to the system as shown in figure 4-19

Fig 4-18 checking for leaks using alcohol

Fig 4-19 Convectron attached to System

90

(5) Attach the clamps of the Multimeter to the bottom of the chamber as shown in figure 4-20

(6) Place the Quartz crystal in place

(7) Close tight vacuum chamber

(8) Connect all electrical appliances to power source

Fig 4-20 Multimeter Connections

2 Starting up the System

(1) We turn on all the devices as such Check all systems are ready to function Reset all values

that might be left over from previous tests

(2) Start the thickness monitor and set all values for this experiment In our case we got to testing

the system but not actual coating So we used the simulation mode of the thickness monitor as

shown in figure 4-21

Fig 4-21 Simulation Mode

91

(3) Start the turbo pump Make sure the lid on the vacuum chamber is tightly closed

(4) Start convectron and record initial pressure

(5) Start Multimeter and record initial current

3 Coating Process

(1) If we have the deposition material inside the filament boat the power source for the high

current must be started as well

(2) Record all initial values for thickness current pressure

(3) For an ideal experiment we need a thickness of around 101 nm a pressure of Torr and

a current of 300 A

44 Results

From previous experiments we have shown that we can turn a LED into a laser by means of AR

Coating In figure 4-22 shown below we can compare the actual results of a Diode before and after AR

coating From the blue line we can see that when the diode is at a current of 15mA its light will change

from LED to laser and if we look at the red line its critical current is around 30 to 35 mA

Fig 4-22 AR Coating Comparison for Laser Diodes

This means that the light emitted is not as strong as if the diode had been coated because inside the

chamber there must be some excitation first so the reflectivity of both sides inside the diode must be high

So because of the coating in one of the sides we have opened a door and let the light come out so the

critical current is risen as such and will be higher value than that of before the coating

92

In the following figures we can see the difference between before and after coating in a material The

thickness is around 1016 nm for this material

Fig 4-23 Before Coating

Fig 4-24 After Coating

93

Chapter 5 CONCLUSIONS AND RECOMMENDATIONS

51 Conclusions

For the first part of this independent study taking into consideration the data that came out of our

research and that sent by the provider we can say

1 SUM 23 after heat treatment will unexpectedly develop cracking in the middle of the tensile

testing process and suddenly break

2 Itrsquos possible that in the process of heat treatment to the SUM 23 material the treatment was not

uniform and this will create a pre-loaded moment force on one side that pushes on the other side

of the specimen resulting in material deformation

3 In the process of attaching the strain gauges to the materials it is very easy to make errors due to

poor adhesion or sudden removal in the tensile testing process

For our second part of the independent study the following can be made

1 At the beginning of this independent study we had no idea what Bose-Einstein Condensate was

or what was its purpose After much literature we finally comprehended the basic principles to

put into practice for our research

2 Our systemrsquos basic working principles and equipmentrsquos complexity are a little difficult to grasp

but hopefully we were able to understand enough of it

3 Theoretically from relation between the power and current we can know the advantages and

disadvantages of AR Coating

4 We were able to assemble the system and run test on its functions Even though we were able to

do this there is still much more work left to do with this system

52 Recommendations

For the Tensile Testing the following can be said

1 Ask the provider to check on the process of heat treatment on the SUM 23 material and give

them the information we have gathered through our test so they can correct for the mechanical

properties found if any change is needed

2 To avoid the problem of the inaccuracy of the poor adhesion of strain gauges we can attach

multiple strain gauges to the same one specimen so as to correlate data and improve our results

For the AR Coating the following can be said

1 We need to make sure that there are no physical defects on the main body of the chamber so as to

achieve maximum efficiency in the vacuum process If there was then the vacuum will arrive to

certain point and then start to decrease

2 It would be preferable to add some sort of visual aid that will allow the user to check the inside of

the chamber without actually opening it This will help us determine at what times we should

manipulate the current to better evaporate the substrate

94

REFERENCES

[1] A L Window Strain Gauge Technology Elsevier Applied Science London and New York 2nd

Edition 1992

[2] CC Perry and HR Lissner Strain Gauge Primer McGraw-Hill Book Co Inc New York 1955

[3] James W Dally William F Riley McGraw-Hill 1978

[4] University of Colorado Boulder BEC - What is it and where did the idea come from

httpwwwcoloradoeduphysics2000becwhat_is_ithtml

[5] Ultraslow Light amp Bose-Einstein Condensates Two-way Control with Coherent Light amp Atom

Fields Harvard Hau Lab Dr Lene Vestergaard Hau Optics amp Photonics News 16 1995

[6] The Art of Taming Light Ultra-slow and Stopped Light Harvard Hau Lab Dr Lene

Vestergaard Hau Europhysics News 2004

[7] Nonlinear Optics Shocking Superfluids Harvard Hau Lab Dr Lene Vestergaard Hau Nature

Physics 2007

[8] Model P3 Strain Indicator and Recorder Instruction Manual Vishay Micro-Measurements 2005

[9] Granville-Phillips Series 375 Convectron Vacuum Gauge Controller Instruction Manual Brooks

Automation 2008

[10] Effect of Film Thickness on the Validity of the Sauerbrey Equation for Hydrated Polyelectrolyte

Films Vogt Lin Wu White 2004

[11] Quartz Crystal Microbalance Study of DNA Immobilization and Hybridization for DNA Sensor

Development Chang Zhao 2008

[12] Installation of Strain Gages with SR-4 PrecoatAdhesive Vishay Micro-Measurements 2005

[13] Strain Gauge Measurement ndash A Tutorial National Instruments 1998

[14] Correlation between Vickers Hardness Number and Yield Stress of Cold-Formed Products

Yavuz Tekkaya

[15] httpsenwikipediaorg

Page 12: PC Hinge Materials Testing and AR Laser Diode Coating

12

But when the laser diode generates light but the laser diode canrsquot produce light on itself it

must wait for the current to be higher than certain value which is called the critical current Until

the light goes over this threshold then it is considered laser light if not it is just considered as a

common LED light source Please refer to figure 1-3

Fig 1-3 Comparison between LED and Laser Diode

As we can see from figure 1-3 all of the light that goes over the critical current is laser light

and so the external cavity semi-conductor laser that we built needs Anti-Reflective Coating

because the method we want to use needs an external cavity laser that has been covered with AR

Coating and a Diffraction Grating We use this configuration first by shooting the laser to the

grating and this will be shot back to the laser creating the external resonance cavity which is

shown in figure 1-4

Fig 1-4 External Cavity Design

13

Two configurations are shown the Littrow Configuration and the Littman-Metcalf

Configuration The Littrow configuration contains a collimating lens and a diffraction grating as

the end mirror The first order diffracted beam provides optical feedback to the laser diode which

has AR Coating The emission wavelength can be turned by rotating the diffraction grating A

disadvantage is that it also changes the direction of the output beam

In the Littman-Metcalf configuration the grating orientation is fixed and an additional mirror

is used to reflect the first order beam back to the laser diode The wavelength can be turned by

rotating that mirror This configuration offers a fixed direction of the output beam and also tends

to exhibit smaller line width as the wavelength selectivity is stronger A disadvantage is that

zero order reflection of the beam reflected by the tuning mirror is lost so that the output power is

less than that of a Littrow laser

13 Methodology

The aim of this research is to find the mechanical properties of materials after being

subjected to tensile testing through finite element analysis observations and determine what

material is best for our purposes taking into consideration the strength and durability of the

material among other properties to find use and applications for the AR coated laser diodes to

further improve the grasp of the Bose-Einstein condensation working principles

14 Organization of the Thesis

The research paper includes five chapters

1 Chapter 1 explains the motivation background objective and methodology of this study

2 Chapter 2 explains the working principles and basic knowledge needed to understand this

study

3 Chapter 3 explains the tensile testing in detail steps methods and results

4 Chapter 4 explains the AR coating in detail steps methods and results

5 Chapter 5 is the conclusions taken from the results shown in chapter 3 and 4 and

recommendations done after arranging and critical thinking

14

Chapter 2 BASICS THEORIES

21 Tensile Testing

After a specimen is tested with the use of tensile testing we can get the Stress-Strain Curve using the

relation between tension and displacement Typical curves are shown in Fig 2-1

(a) Ductile materials (b) Brittle materials

Fig 2-1 Stress-Strain Curve

The curve is unique for each material and is found by recording the amount of deformation at distinct

intervals of tensile or compressive loads Thanks to the use of the Stress-Strain curve we can get very

useful information such as

211 Youngrsquos Modulus (E)

As shown in Fig 2-1 as long as the external load is not greater than the Proportional Limit the Stress

(σ) and Strain (ε) remain as a linear relation fulfilling Hookersquos Law

σ = Eε

The slope is the constant factor the inverse of the modulus of elasticity E also called Youngrsquos

modulus When the external load goes over the proportional limit the stress-strain relationship doesnrsquot

follow the linear relation anymore but the deformation remains flexible When the load is released the

deformation is completely eliminated and the specimen goes back to its original state This is called

15

Elastic Deformation When the external load goes over the Elastic limit only then does the specimen

presents Plastic Deformation This type of deformation which is irreversible even when the load is

removed comes after the material does under elastic deformation so this means the object will first come

part way to its original shape Common metals and ceramics have roughly the same elastic limits

212 Yield Strength and Yield Point

Some materials display very evident yield phenomena while some materials donrsquot as shown in Fig

2-2 After we exceed the elastic limit if we continue to exert load when we arrive to a certain value

which differs under different materials and external conditions there is sudden decrease in stress and this

is called the Yield Strength and can be defined as the stress at which a material begins to deform

plastically using the equation

σyield =

Where P is the tension force and Ao is the original cut-off area

The stress remain at a certain value after the decrease but the strain increases this phenomena can be

easily appreciated when studying the behavior of common Carbon Steel Fig2-2 (a) but most metals (like

Aluminum Copper or High Steel Carbon) donrsquot display this kind of behavior as shown in Fig 2-2 (b)

Arriving to this point is very difficult and the most commonly used method for this is to add a 02 or

0002 offset yield strength to the curve This point is held constant on the strain axis of the curve and

from the 0002 position we draw a straight line parallel to the linear relationship line the point at where

this line and the stress-strain curve intercept is the point we take as the 02 offset yield strength

(a)Evident (b) Non-evident

Fig2-2 Stress-Strain Curve Comparison on Metals

16

213 Ultimate Tensile Strength and Breaking Strength

After materials undergo yield they keep lending strength and hardening phenomena occurs (work

hardening) on the material and the external load increases When it has reached the highest point this is

called the Ultimate Tensile Strength (UTS) as shown in Fig2-1 The UTS is defined as

σUTS =

Where Pmax is the load at the materialrsquos ultimate tensile strength point and Ao is the original cut-off

area For brittle materials the ultimate tensile strength is the most important mechanical property for

ductile materials the ultimate tensile strength is not commonly used for industrial and designing purposes

because upon arriving to this value the material already has forgone great plastic deformation After the

specimen goes through UTS there will be necking phenomena which is a mode of tensile deformation

where relatively large amounts of strain localize disproportionately in a small region of the material It

results from instability during tensile deformation when a materialrsquos cross-sectional area decreases by a

greater proportion than the material strain hardens The specimen continues to elongate until it finally

breaks and the load at this point is called Breaking Strength The breaking strength is defined as the

greatest stress in tension that a material is capable of withstanding without rupture

Where Pf is the load at the materialrsquos breaking strength point and Ao is the original cut-off area

214 Poissonrsquos Ratio (ν)

For elastic deformation when materials are compressed in one direction they tend to expand in the

other two directions perpendicular to the direction of compression This is called the Poissonrsquos Effect

The Poison Ratio is a measure of the Poissonrsquos effect It is the ratio of the fraction of expansion divided

by the fraction of compression for small values of these changes

ν=-

215 Strain Gauge Basic Principles

The strain gauge is a device used to measure the strain of an object Itrsquos an elongated metal resistor

which is attached to the specimen being measured and when the specimen is under strain and starts to

deform the strain gauge will have a change in the resistance With the change in value we can calculate

the elementrsquos strain or elastic modulus and the Poissonrsquos ratio

It takes advantage of the physical property of electrical conductance and its dependence on the

conductorrsquos geometry When the electrical conductor (the specimen being tested) is stretched within the

limits of elasticity such that it does not break or deform plastically it will become narrower and longer

17

which increases the electrical resistance through-out From the measured resistance of the strain gauge

the amount of stress may be inferred by using the relations

R=

Where R is the original resistance value is the electrical resistivity lo is the original length of the

conductor and Ao is the original cross sectional area of the conductor If after the application of tension

the change in length is Δl let the length of the specimen be l = l + Δlo and the tension is the same

through-out So

And the resistance is

The Gauge Factor is the ratio of relative change in electrical resistance to the mechanical strain in

other words it is the relative change in length It is defined as

The strain gauge was invented in 1938 by Edward E Simmons and Arthur C Ruge and the most

common type consists of an insulating flexible backing which supports a metallic foil usually made of a

brass-nickel alloy It is attached to the specimen by a suitable adhesive As the object is deformed the foil

also deforms and this causes the electrical resistance to change Then this is usually measured using a

Wheatstone bridge shown below and is related to the strain by the Gauge Factor

Fig2-3 Basic Structure of Strain Gauge

18

Fig 2-4 Strain gauge attached to Wheatstone bridge

22 Hardness Testing Basic Principles

221 Brinell Scale BHN

The Brinell Scale characterizes the indentation hardness of materials through the scale of penetration

of an indenter loaded on a material specimen The typical test uses a 10mm diameter steel ball as indenter

(usually of value equal to BHN450) with a 29kN force For softer materials smaller force is used The

indentation is measured and BHN is calculated using the relation

BHN =

radic

Where F is the applied force usually within the range of 100 250 500 750 1000 1500 2000 2500

and 3000 kgf D is the diameter of indenter usually within the range of 5mm or 10mm plusmn0005 margin

and d is the diameter of indentation usually around 2mm Its units are of Kgmmsup2 but are not normally

written

First proposed by Swedish engineer Johan August Brinell in 1900 it was the first widely used and

standardized hardness test in engineering and metallurgy although the large size of indentation and

possible damage to specimen limits its usefulness

Fig 2-5 Brinell Indentation Fig2-6 Brinell Hardness Tester

19

222 Rockwell Scale HR

The Rockwell scale is a hardness scale based on the indentation hardness of a material The Rockwell

test determines the hardness by measuring the depth of penetration of an indenter under a large load

compared to the penetration made by a preload The indenter is forced into the specimen under a

preliminary load When equilibrium is reached a measuring device follows the movements of the

indenter and responds to changes in depth of penetration of the indenter While the preload is still being

applied additional major load is applied resulting in increased penetration When equilibrium is reached

again the major load is removed but the preload is maintained Removing the major load allows partial

recovery and reduces the depth of penetration The permanent increase in depth of penetration resulting

from the application and removal of the major load is used to calculate the Rockwell number using the

relation

HR = E ndash e

Where E is a constant depending on the form of the indenter 100 units for diamond indenter and 130

units for steel ball indenter e is the permanent increase in depth of penetration due to the major load

measured in units of 0002mm

Fig 2-7 Rockwell Indentation

When testing materials indentation hardness is related linearly to the tensile strength The important

relation permits economically important nondestructive testing of bulk metal deliveries with lightweight

equipment like the Rockwell tester shown below in figure 2-7

Fig 2-8 Rockwell Hardness Tester

20

There are different scales denoted by a single letter that use different loads or different indenters

The result is a dimensionless number denoted as HR X where X will be the letter denoting the scale as

shown below in table 2-1

Table 2-1 Rockwell Hardness Test Scale

Differential depth hardness measurement was first conceived in 1908 by Viennese professor Paul

Ludwik It eliminated the errors associated with the mechanical imperfections of the system such as

backlash and surface imperfections in the specimen Rockwell testing has an advantage over Brinell

testing because the latter was slow itrsquos not useful on fully hardened steel and left too large an impression

to be considered nondestructive

The tester was co-invented by Hugh M Rockwell and Stanley P Rockwell The requirement for this

tester was to quickly determine the effects of heat treatment on steel bearing races

21

223 Vickers Hardness Test HV

This is a type of microindentation hardness test where a diamond indenter of specific geometry is

impressed into the surface of the test specimen using a known applied force ranging from 10 to 1000

grams This type of tests usually has forces of 2N and produce indentations of about 50μm They can be

used to observe changes in hardness on the microscopic scale It is difficult to standardize the

microhardness measurements because it has been found that the microhardness of almost any material is

higher than its macrohardness The values also vary with load and work-hardening effects of materials

The Vickers test is often easier to use than other hardness tests because the required calculations are

independent of the size of the indenter and the indenter can be used for all materials It can be used for all

metals and has one of the widest scales among hardness tests The unit of the Vickers test is denoted as

HV and can be converted to units of Pascal (Pa) but it is not a measurement of pressure The hardness

number is determined by the load over the surface area of the indentation and not the area normal to the

force

A square-based pyramid shaped diamond is use as the indenter It has been established that the ideal

size of a Brinell impression was 38 of the ball diameter As two tangents to the circle at the ends of a

chord 3d8 long intersect at 136plusmn05deg it was decided to use this as the angle of the indenter giving an

angle to the horizontal plane of 22deg on each side The HV number is determined by the ratio FA where F

is the force applied to the diamond in kgf and A is the surface area of the resulting indentation in mmsup2 A

can be determined by the relation

A =

Where A is the surface area of indentation and d is the average length diagonal left by the indenter

This can be approximated as

A =

Then the Vickers Number is

HV =

=

Vickers hardness number is reported as xxxHVyy or xxxHVyyzz (if duration of applied force differs

from 10s to 15s) where xxx are replaced by the hardness number yy is the load in kg and zz indicates

loading time The values are generally independent of test force

The test was developed in 1921 by Robert L Smith and George E Sandland at Vickers Ltd as an

alternative to Brinell method to measure the hardness of materials

22

Fig 2-9 Vickers Indentation Fig 2-10 Vickers Hardness Tester

23 AR Coating

231 Bose-Einstein Condensate

The Bose-Einstein Condensate or BEC is a state of matter of a dilute gas of bosons cooled to

temperatures very near absolute zero around 0K or -27315degC Under such conditions a large fraction of

the bosons occupy the lowest quantum state where the quantum effects become apparent on a

macroscopic scale This gave birth to the Bose-Einstein Statistics which are the rules that govern the

behavior at this state It is one of the two possible ways in which a collection of indistinguishable particles

may occupy a set of available discrete energy states The aggregation of particles in the same state

accounts for the cohesive streaming of laser light and the frictionless creeping of superfluid helium (an

application discussed later) Bose and Einstein recognized that a collection of identical and

indistinguishable particles can be distributed this way This theory applies only to those particles not

limited to single occupancy of the same state particles that do not obey the Pauli Exclusion Principle

restrictions Such particles are the Bosons named after the statistics that correctly describe their behavior

This phenomenon was first predicted by Satyendra Nath Bose around 1924 when he considered how

groups of photons behave He then asked Albert Einstein for help publishing his discoveries to which

Einstein agreed and gave follow up supporting these findings The resulting efforts became the concept of

a Bose gas governed by the Bose-Einstein Statistics described above Einstein demonstrated that cooling

bosonic atoms to a very low temperature would cause them to condense into the lowest accessible

quantum state resulting in a new form of matter

The first gaseous condensate we produced by Eric Cornell and Carl Wieman at the University of

Colorado at Boulder NIST ndash JILA lab sung a gas of rubidium atoms cooled to 170 nK which earned

them the 2001 Nobel Prize in physics together with Wolfgang Ketterle from MIT The transition to BEC

occurs below a critical temperature which for a uniform three dimensional gas consisting of

non-interacting particles with no apparent internal degrees of freedom is given by

23

Tc =

(

)

asymp 33125

Where Tc is the critical temperature n is the particle density m is the mass per boson h is the

reduced Planck constant k is the Boltzmann constant and ζ is the Riemann zeta function

There are two classes of elementary particles defined by whether their quantum spin is a nonnegative

integer or an odd half integer A Bose-Einstein Condensate is shown below in figure 2-11

Fig 2-11 Bose Einstein Condensate at different scales

Bosons are the particles whose quantum spin is a nonnegative integer (s = 0 1 2 etc) Examples of

bosons include fundamental particles (Higgs Boson Photons W and Z Bosons Gluons Gravitons etc)

composite particles (Mesons Hadrons Nuclei and Atoms of Carbon-12 and Helium-4) and

quasi-particles Bosons are considered force carrier particles The Bosons differ from Fermions in that

there is no limit to the number that can occupy the same quantum state This is called the Pauli Exclusion

Principle

The Pauli Exclusion Principle says that no two identical fermions may occupy the same quantum state

simultaneously in other words this means that the total wave function for two identical fermions is

anti-symmetric with respect to exchange of the particles This means that no two electrons in a single

atom can have the same four quantum numbers

Fermion is any particle characterized by Fermi-Dirac Statistics and follows the Pauli Exclusion

Principle described above Quarks Leptons and composite particles (Hadrons Nuclei and Atoms of

Carbon-13 and Helium-3) made of an odd number of these are considered Fermions It can be an

elementary particle such as the electron or a composite particle such as the protons Following the Pauli

24

Exclusion Principle only one fermion can occupy a particular quantum state at any given time If multiple

fermions have the same spatial probability distribution then at least one property of each fermion must be

different Fermions are usually associated with matter because composite fermions are key building

blocks of matter (neutrons and protons)

Fermionsrsquo behavior by the Fermi-Dirac Statistics which describes the energies of single particles in a

system comprising of many identical particles It applies to identical particles with half-odd integer spin

in a system of thermal equilibrium The particles in the system are assumed to have negligible mutual

interaction This allows the many-particle system to be described in terms of single-particle energy states

The result is the Fermi-Dirac distribution of particles over these states and includes the condition that no

two particles can occupy the same state which has considerable effect on the properties of the system

In quantum mechanics the position of an object is uncertain An object has a definite probability of

being at any given point in space This probability is encoded in the wave function mentioned earlier If

one concentrates a large number of identical bosons in a small region then it is possible for their wave

functions to overlap so much that the bosons lose their identity When this happens thatrsquos a Bose-Einstein

Condensate It is only possible at very low temperatures because at high temperatures the individual

bosons have small wave functions and move rapidly which causes them to fly apart

For now applications are still restricted because there are still some setbacks regarding BECs They

are extremely fragile they are being produced in small quantities with just a few million atoms at a time

and finally they can only be made from certain types of atoms Some examples are the atom laser Ketterle

in which a conventional light lase emits a beam of coherent photons this means they are all in phase and

can be concentrated to an extremely small bright spot BECs can slow down light as demonstrated by

Prof Lene Hau PhD in 2001 by the use of a superfluid [7] These manipulations could develop into

new types of telecommunications technology optical storage and quantum computing

BECs are related to super-fluidity and super-conductivity Super-fluidity is the state of matter in

which the behavior is that of a fluid with zero viscosity It was discovered in liquid helium but now it has

applications in astrophysics high-energy physics and theories of quantum gravity

Super-conductivity is a phenomenon of exactly zero electrical resistance and expulsion of magnetic

fields occurring in certain materials when cooled below a characteristic critical temperature A

super-conductor is shown below in figure 2-12

Fig2-12 Super Conductor

25

232 AR Coating Basic Principles

Anti-reflective (AR) coating is a type of optical coating applied to the surface of lenses and other

optical devices (in our case we planned to apply it to a laser diode) to reduce reflection This improves

the efficiency of the system since less light is lost The primary benefit is the elimination of the reflection

itself

When light the medium (glass) it will produce reflection if 100 of the light comes from the air and

enters the glass because therersquos a difference between the index of refraction some of the light will go out

and when the light is coming out of the glass into the air once again because of the difference between

index of refraction some of the light wonrsquot be able to pass through the medium

When the light makes the first trip into the glass there was a loss of about 4 in the reflection and

when the light makes the trip back outside there was another loss of about 4 so when we assume that

100 of the light interacts with the medium actually therersquos just about 92 acting (we neglect the light

absorbed by the glass around 05) To illustrate this idea please refer to figure 2-13

Fig 2-13 Simple Model for Light in Glass Medium

When we apply the AR Coating the light that enters will only have a loss of about 05 and when

making the trip back outside again only 05 of light is loss so we get the result of increasing the light

passing through up to 99 (again neglecting the light absorbed by the glass around 05) To illustrate

this idea please refer to figure 2-14

26

Fig 2-14 Simple Model for Light in Glass Medium after AR Coating

The AR Coating can reduce reflection of incoming light In the case that light hits perpendicular to

the surface of the medium the intensity of the reflection can be calculated using the Reflection

Coefficient

Where n0 and ns are the refractive indices of the first and second media respectively The value of R

varies from 0 (no reflection) to 1 (all light reflected) and is usually quoted as a percentage

Complementary to R is the transmission coefficient or Transmittance If absorption and scattering are

neglected then the value of Transmittance is always 1-R then if a beam of light with intensity I is

incident on the surface a beam of intensity RI is reflected and a beam with intensity TI is transmitted to

the medium

The optimal value is called the Optimal Index of Refraction and is described as

For glass with ns around 15 in air (n0 around 10) then the optimum refractive index will be n1 =

1225

To reduce the refraction in this case we now mean the one that is produced inside the chamber of the

Laser diode the easiest way is to apply a low reflectivity AR coating on the surface of the laser To

measure the appropriate thickness of the coating layer we can use the equations described above By

applying a coat exactly

thickness film we can assure that a certain wavelength is transmitted The

27

reflected waves from the back of the glass medium will be half a wavelength out of phase So they

interfere destructively Because all reflected waves are interfered the maximum amount of light passes

through the coating Please refer to figure 2-15 to illustrate this idea

Fig 2-15 Light Passing through AR Coat and Glass

The most common process to attain this final product is by vacuum deposition For the best coating

results we need to lower the pressure inside the vacuum system to torr

Fig 2-16 Lens without (Top) and With (Bottom) AR Coating

28

233 Laser Diode Basic Principles

A laser diode is a laser whose active medium is a semiconductor similar to that found in

light-emitting diodes (LEDs) Please refer to figure 2-17 The most common type of laser diode is formed

from a p-n junction and powered by injected electric current

Fig 2-17 Laser Diode

Laser diodes are formed by doping a very thin layer on the surface of a crystal wafer The crystal is

doped to produce the n-type region and a p-type region one above the other

By referring to figure 1-2 we can see the basic structure of a working laser When the laser diode has

a current passing through it the light will get excited inside its gain medium and then will start to

resonate this process is called pumping The current exceeds the critical current and then it comes out as

laser light Please refer to figure 1-3 Since we use an external cavity laser we need to apply the AR

coating to the diode and adjust a diffraction grating The laser light comes out the diode and bounces on

the grating making the resonance externally and this becomes the ldquocavityrdquo as shown in figure 2-18

Fig 2-18 Tunable Laser Basic Configuration

29

The most important feature of the external cavity laser is that we can adjust the wavelength easily just

by changing the diffraction gratingrsquos angle and in the end this is the output wavelength of the laser For

different wavelengths there will be different levels of visible light as shown in figure 2-19

Fig 2-19 Light Spectrum

234 Quartz Microbalance System

A Quartz Crystal Microbalance is an instrument that measures a mass per unit area by measuring the

change in frequency of a quartz crystal resonator The resonance is disturbed by the addition or removal

of a small mass due to oxide growthdecay or film deposition (which is the case in our study) at the

surface of the acoustic resonator The QCM can be used under vacuum in gas phase and more recently in

liquid environments It is useful for monitoring the rate of deposition in thin film deposition systems

under vacuum Frequency measurements are easily made with high precision

For our research we used the Sigma Instruments SQM-160 RateThickness Monitor shown in figure

2-20

Fig 2-20 Front and Back Panels of SQM-160

30

The microbalance uses Quartz as the resonator Quartz is one member of the family of crystals that

experience the Piezoelectric Effect

Piezoelectricity is the charge that accumulates in certain solid materials in response to applied

mechanical stress It means electricity resulting from pressure It was discovered in 1880 by Jacques and

Pierre Curie It is understood as the linear electromechanical interaction between the mechanical and the

electrical state in crystalline materials with no inversion symmetry It is a reversible process in that

materials exhibiting direct piezoelectricity also exhibit the reverse This means that the internal generation

of electrical resulting from applied mechanical force and vice versa

By using the piezoelectric effect we can probe as an acoustic resonance by electrical means Applying

alternating current to the quartz crystal induces oscillations This creates a shear wave We can use these

qualities to determine the resonance frequency at high accuracy

The frequency of oscillation of the crystal is partially dependent in the thickness of the crystal During

normal operation all the variables are held constant so a change in thickness correlates directly to a

change in frequency As mass is deposited or etched away the thickness increases or decreases and so the

frequency of oscillation changes accordingly With some simplifying assumptions the frequency change

can be quantified and correlated precisely to the mass change using the Sauerbreyrsquos Equation

Developed by G Sauerbrey in 1959 it is a method for correlating changes in the oscillation

frequency of a piezoelectric crystal with the mass deposited on it It is defined as below

Where f0 is the Resonant frequency Δf is the Frequency change Δm is the mass change A is the

piezoelectrically active area of the crystal q is the Density of quartz (2648 gcmsup3) and μq is the Shear

modulus of quarts(2947x gcmssup2)

Because the film is treated as an extension of thickness Sauerbreyrsquos equation only applies to systems

in which the following 3 conditions are met

Deposited mass must be rigid

Deposited mass must be distributed evenly

The frequency change

lt002

If the change is greater than 2 the Z-match method must be used to determine the change in mass

It is defined as

Where fL is the frequency of the loaded crystal fU is the resonant frequency Nq is the frequency

constant (1668x HzAring) Δm is the mass change A is the piezoelectrically active area of the crystal

31

q is the density of quartz Z is the method constant f is the density of film μq Is the shear modulus of

quarts and μf is the shear modulus of film

The Sauerbrey equation cannot be applied to systems under liquid medium

The crystals are seed crystals plated with gold on both top and bottom for applications A crystal is

shown in figure 2-21 The QCM consists of a thin piezoelectric plate with electrodes evaporated on both

sides Due to the piezoelectric effect AC voltage across the electrodes induces a shear deformation and

vice versa The electromechanical coupling provides a simple way to detect an acoustic resonance by

electrical means

The Z also called Z-factor is a constant value for different materials and it is shown together with the

density of different materials in table 2-2 below

Fig 2-21 QCM Crystals

The Oscillator of the SQM-160 is shown in figure 2-22 and the equivalent circuit for the Resonant

Oscillator is shown in figure 2-23

Fig 2-22 SQM-160 Oscillator

32

Fig 2-23 Oscillator Circuit

33

Table 2-2 Z-Ratios for Different Materials

Table 2-2 Continued

34

Table 2-2 Continued

35

Table 2-2 Continued

36

Table 2-2 Continued

37

Table 2-2 Continued

38

Table 2-2 Continued

235 Vacuum Chamber System

Vacuum Evaporation is the process of depositing thin films of materials onto surfaces The technique

consists of pumping a vacuum chamber to pressures of less than torr and heating a material to

produce a flux of vapor in order to deposit the material onto a surface The material to be vaporized is

typically heated until its vapor pressure is high enough to produce a flux several Angstrom per second by

using an electrically resistive heater or bombardment by a high voltage beam The process was invented

by Henri Nestle in 1886 for food industry

In here the system has been pumped to a vacuum of Torr When a high current is passed

through the filament boat the filament boat is heated over the desired metal evaporation temperature and

so evaporation starts When the evaporation process is finished and the metal cools down crystals

condensate in the surface of the wafer From the weight of the evaporated material the distance between

the filament boat and the wafer we are able to calculate the deposition thickness and we can also use the

mass detector follower like the Quartz crystal resonator microbalance system In the process of

evaporation we usually use a board in between the filament boat and the wafer This is because before we

arrive to the desired evaporation temperature there will be some impurities that will be vaporized in the

controlled environment so we first use a small current and the board in between to get rid of those

impurities and this raises the purity of the deposition material

39

A vacuum evaporation system is shown in figure 2-24

Fig 2-24 Vacuum Evaporation System

Rough Vacuum 760 ~ 1 torr

Medium Vacuum 1 ~ torr

High Vacuum ~ torr

Ultra-High Vacuum Lower than torr

Table 2-3 Classification of Vacuum

For our study we need to use a Turbo Pump A regular turbo pump is shown in figure 2-25

Fig 2-25 Turbo Pump

For our research we used the Pfeiffer TCP 015 Electronic Drive Unit and Granville Phillips 375

Convectron shown below in figure 2-26

40

Fig 2-26 Control and Measurement Equipment

The electronic drive controls the turbo pump and the Convectron measures the pressure inside our

chamber The turbo pump is a type of vacuum pump used to maintain high vacuum Most turbo pumps

are centrifugal When we start the pumping we need to use a mechanical pump so as to decrease the

pressure inside the system from constant atmospheric pressure to torr and then the use dispersion

pump to continue the vacuum until we get to the desired pressure We need to notice though when we

start the dispersion pump we canrsquot turn off the mechanical pump and they both need to run together If

we need to turn off the pumping we first turn off the dispersion pump wait for it to completely stop and

then turn off the mechanical pump

Our completely assembled system is shown in figure 2-27 below

Fig 2-27 Complete System

41

Chapter 3 TENSILE TESTING IN DEPTH

31 Experimentrsquos Purpose and Principles

By means of Universal testing machine and Strain gauges we were able to observe discuss and

analyze the phenomena created when a specimen of certain material is manipulated under an external load

and determine the stress strain and deformation values later we can use the graphing methods of

stress-strain diagram to describe it

The main point of this experiment is that after the tensile specimen is tested use computer analysis

and the actual strain data and after statistical adjustment make the final results report (Tensile testing

experiment is in accordance with ASTM E8)

32 Experimentrsquos Equipment

321 Universal Testing Machine

For the materials testing experiment part of this research we use a Universal Testing Machine as

shown in figure 31 The maximum load it can apply is 100 Ton After the test specimen is secured on the

device with the use of instrumentation the load exerted and the effects of this become apparent on the

specimen and even the smallest of changes can be recorded For our research we used the Chun Yen

Testing Machines Co Ltd 100 Ton Micro Computer Universal Tensile Tester

Fig 31 Universal Testing Machine

42

Table 31 shows the specifications for this machine

Max Capacity 100 Ton

Accuracy plusmn1

Tension (mm) Max Space 1150mm

Grip for Rod 20-70mm

Ram Stroke 250mm

Effective Column Interval 940mm

Crosshead Speed 300mmmin

Testing Speed 0-50mmmin

Volume of Machine 1700times1000times3350mm(LtimesWtimesH)

Volume of Control Panel 1000times800times1500mm(LtimesWtimesH)

Weight 8000kg

Power 3∮220V 20A

Computer AMD K6-2-350

OS Windows XP

Screen 15rdquo CRT

Table 3-1 Chun Yen Testing Machine Specs Table

The connections diagram is shown in figure 3-2

Fig 3-2 Diagram for System Connections

43

When the test specimen is placed when the external force is applied the Load Cell can measure the

size of the applied force and the Encoder measures the expansion rate of change The Local Controller

receives all the information from the 2 units after arranging the results they are displayed in the

computer and they can be afterwards submitted for more complex analysis such as Finite Element

Analysis and we can get the Stress-Strain Diagram

322 Strain Measurement Equipment

The equipment used in our research provides a four-channel measurement that means we can use up

to 4 strain gauges at a time to do our measurements and provides 3 different bridge arrangements as

shown in figure 3-3

(a) (b) (c)

Fig 3-3 Input Connections for Strain Indicator

Figure 3-3 (a) is the Quarter Bridge (b) is the Half Bridge and (c) is the Full Bridge and Transducers

For our study we used the Quarter Bridge and use the Strain Gauge values to decide the position of the

connecting wires The Strain indicator is shown in figure 3-4

Fig 3-4 Vishay Micro-Measurements Model P3 Strain Indicator and Recorder

44

Input Connections Tool Free eccentric lever release

4-channel input

Wire diameter16-28AWG

Bridge Configurations Quarter- Half- and Full Bridge

Bridge Impedance 60-2000Ω

Display 128 64 pixel FSTN positive gray LCD

Data Conversion AD Converter filter

Measurement Range Resolution Strain Range plusmn155mVV

Resolution plusmn00005mVV

Measurement Accuracy plusmn01 of reading plusmn3 counts

Gage Factor Control 0500-9900

Balance Control Software either manual or automatic

Bridge Excitation 15VDC nominal

Communication Interface USB Cable Included

Data Storage Removable Media Card

Shunt Calibration Across bridge completion resistors controlled

by software When Gage Factor=200

120Ω350Ω1000Ω

Analog Output Value 0 to 25V max

Ranges plusmn320 microε plusmn3200 microε plusmn32000 microε

Error 05 output voltage +5mV

Max Error 14 output voltage + 20mV

Update rate 480 samplessec

Output Load 2000Ω

Power Battery Two Alkaline D cells

Battery life 400 hours typ

USB 5V 100mA

Operational Environment Temperature 0-50

Humidity Up to 90 Non-condensing

Case Aluminum Alloy

Size and Weight 228times152times152(mm) 20(kg)

Table 3-2 Vishay Micro-Measurements Model P3 Strain Indicator and Recorder Specs

45

323 Strain Gauge

The strain gaugersquos main basic principle is to use a resistancersquos characteristics to measure the strain

The inside connections of the strain indicator are shown in figure 3-5

Fig 3-5 Inner Connections

As shown above this is a quarter-bridge connection We connect equal-length 3 wires to the 2

connections allowed by the strain gauge wire 1 and 3 can be used to cancel out the effects of temperature

to the resistance and because of the addition of wires 1 and 3 wire 2 can directly measure the experiment

results from the strain gauge and therefore the strain developed with no influence of temperature

If there were no two measuring leads then the relations will be

R 4 =R g +2R L

Where Rg is the Strain Gauge Value and RL is the wire resistance then

4

4

R

R=

Lg

g

RR

R

2

=

gL

gg

RR

RR

21

amp

4

4

R

R=

g

g

R

R(1- L)

Where L is the Signal Loss Factor and so

L =gL

gL

RR

RR

21

2

g

L

R

2R if

g

L

R

2Rltlt1

46

(Actual Value R g =120R L =08g

L

R

2Ris always much smaller than 1)

R 4 =R g +2R LR 2 =R 3 =rR gR 1 =R g 32 RR =0

V 0 =V 2)1( r

r

(

4

4

R

R-

1

1

R

R)

The first term describes loss attenuation effects second term describes loss of balancing capabilities

effects

V 0 =V 2)1( r

r

[

)2

(Lg

g

RR

R

+

T

Lg

g

RR

R

)

2( + T

Lg

L

RR

R

)

2

2( -(

g

g

R

R) T ]

The first term describes loss attenuation effects and loss of balancing capabilities effects the second

third and fourth terms describe the temperature effects on the wire

For the three-wire method we have

L =gL

gL

RR

RR

1

g

L

R

R if

g

L

R

Rltlt1

V 0 =V 2)1( r

r

[

)(Lg

g

RR

R

+

T

Lg

g

RR

R

)( + T

Lg

L

RR

R

)

2( -

T

Lg

g

RR

R

)( - T

Lg

L

RR

R

)

2( ]

V 0 = V2)1( r

r

)(

Lg

g

RR

R

In the last four terms inside parenthesis we can see the effects of temperature being cancelled out and the

effect on first term is not great so this is the reason why in our research we use three wires

47

324 Specimen Measurements

The tensile specimens used in this research are compliant of ASTM E8 Tensile parameters as shown

in figure 3-6

Fig 3-6 Tensile Specimen

Diameter

D(mm)

Gauge

Length

G(mm)

Smallest

Arc

Radius

R(mm)

Shortest

Area

A(mm)

Total

Length

L(mm)

Clamping

Area

Length

B(mm)

Clamping

Area

Diameter

C(mm)

Bar 125 02 625 01 gt10 gt75 ~ 145 ~ 35 20

Table 3-3 Specifications for Round Bar

33 Experiment Procedure

1 Attaching the Strain Gauge to the Tensile Specimen

(1) Prepare 1 ASTM E8 compliant tensile specimen round bar as shown in figure 3-7

(2) Prepare Strain Gauge as those described in table 3-4

(3) Prepare other consumables and adhesive agent such as epoxy adhesive or

cyanoacrylate adhesive as shown in figure 3-8

48

Fig 3-7 Actual Tensile Specimen

Fig 3-8 Other Materials Used (Such as Alcohol gauze transparent tape adhesive)

Gage Type

EA-06-120LZ-120E

Resistance in ohms at 24∘C

1200plusmn03

Gage Factor at 24∘C

2075plusmn05

Transverse Sensitivity at 24∘C

(+07plusmn02)

Table 3-4 Specifications for Strain Gauge

2 Attaching Strain Gauge

As shown in following figures we shall explain the attachment of the strain gauge

(1) Use sand paper and a rasp to clean thoroughly the surface where the strain gauge will be

attached to

49

(a)

(2) Use alcohol to wash the surface where the strain gauge will be attached and use gauze to rub

it off

(b)

(3) Find a clean surface and clean it with alcohol and gauze

(c)

(4) Place the strain gauge in the clean surface Use a piece of transparent tape on top of the strain

gauge after securely placed rip it off the surface carefully

50

(d)

(5) Use a piece of white paper to mark the place where the strain gauge will be attached and in

this way we can make sure that the strain gauge will be placed as horizontally and vertically

correct as possible

(e)

(6) In the place where we had our mark place the strain gauge

(f)

(7) Carefully lift one side of the tape and apply some of the adhesive agent to both the strain

gauge and specimenrsquos surface

(g)

51

(8) We need to make sure that the gauge and the specimen will be firmly attached so we gently

apply pressure with our thumb

(h)

(9) After the adhesive is fully dry we can carefully rip off the tape

(i)

(10) We need to do the whole process twice one for the horizontally placed strain gauge and one

for the vertically placed strain gauge

52

(j)

(11) We now proceed to solder the wires to the strain gauge

(k)

(12) After soldering we use a Volt Multimeter to measure that there is no contact between wires

If there is none then the specimen is ready for testing

(l)

(13) We now need to measure a 5cm distance and mark it to check and compare the elongation

before and after the tensile testing

(m)

53

Fig 3-9 Specimen-Strain Gauge Process

3 Tensile Test

(1) Enter the computer application that controls the tensile testing machine

(2) Turn on the tensile testing machine main switch

(3) Adjust the hydraulic pump to go back to its original position

(4) Bring the lowering motor down to a distance enough so as to attach the tensile specimen to the

system open the clamps and secure the specimen

(a)

(5) Connect all the necessary wires to the strain indicator equipment

54

(b)

(6) Start the ascending motor and wait for the expansion

(c)

Fig 3-10 Specimen-Tensile Testing Process

4 Start the Test

(1) Enter the software application and enter some variables needed for the experiment in the

specific screen

(2) Go back to the main screen and press the [測試] (measure) button to start the test and auto

recording in the software

(3) After the specimen breaks the mechanical device will automatically stop and ask the user to

enter the total displacement We take out the specimen from the testing machine and adjust the

machinersquos position back to its original position

(4) Save the results information

(5) Record the results from the strain indicator

34 Results

From this experiment we can get the Poissonrsquos Ratio Youngrsquos Modulus and Yield Strength etc and

because of the slippage phenomenon in the clamp at the moment of the test then the Elastic Limit will

display some yield phenomena So omit any undesirable results we just take the Yield portion of the

results as reference

In the process of the experiment the most important part to attend to is the attaching of the strain

gauge because the gaugersquos purpose is to measure the strain developed during the test and this strain

might be very small If the gaugersquos angle change during the test ie is not well attached this will affect

the accuracy of the measurements of Poissonrsquos ratio and Youngrsquos modulus

55

The materials provided by the manufacturer are SUM 23 and SUM 43 steel round bars and these two

types of materials have been through different heat treatment processes so they can be sub-divided

further into untreated material heat-treated material and black surface heat treated material for the two

materials with heat treatment the treatment process and finished are different In the end we only have

the mechanical properties that were calculated after our research of these materials

All of the specifications are identical to those shown in figure 3-6

341 SUM 23

Fig 3-11 SUM 23 Untreated Material

Number 7 10

Hardness(HRB) 74 75

Yield Stress (MPa) 448 440

Tensile Strength (MPa) 544 560

Poissonrsquos Ratio 029 027

Youngrsquos Modulus (GPa) 203 210

Cut-off Area Shrinking () 42 41

Elongation () 1125 1011

Table 3-5 Mechanical Properties of SUM 23 Untreated

56

Stress-Strain Diagram

(a)

(b)

57

Fig 3-12 Stress-Strain Diagrams for (a) 7 Round Bar and (b) 10 Round Bar

Cut-Off Area

(a)

(b)

Fig 3-13 Cut-Off Area of (a) 7 Round Bar and (b) 10 Round Bar

58

SUM 23 Nickel Round Bar

Fig 3-14 SUM 23 Nickel Material

Number 1 2 3 4

Hardness(HRB) 48 50 49 48

Yield Stress (MPa) 370 370 380 400

Tensile Strength (MPa) 455 451 450 450

Poissonrsquos Ratio 028 046 029 026

Youngrsquos Modulus (GPa) 243 303 246 206

Cut-off Area Shrinking () 803 803 726 601

Elongation () 566 65 602 647

Table 3-6 Mechanical Properties of SUM 23 Nickel

59

Stress-Strain Diagram

(a)

60

(b)

(c)

(d)

61

Fig 3-15 Stress-Strain Diagrams for (a) 1 Round Bar (b) 2 Round Bar (c) 3 Round Bar and (d)

4 Round Bar

Cut-Off Area

(a)

(b)

62

(c)

(d)

Fig 3-16 Cut-Off Area of (a) 1 Round Bar (b) 2 Round Bar (c) 3 Round Bar and (d) 4 Round

Bar

63

SUM 23 Black Surface Round Bar

Fig 3-17 SUM 23 Black Surface Material

Number 1 2 3

Hardness(HRB) 51 50 51

Yield Stress (MPa) 378 371 369

Tensile Strength (MPa) 467 465 464

Poissonrsquos Ratio 03 016 04

Youngrsquos Modulus (GPa) 215 266 266

Cut-off Area Shrinking () 986 94 848

Elongation () 748 805 761

Table 3-7 Mechanical Properties of SUM 23 Black Surface Material

64

Stress-Strain Diagram

(a)

(b)

65

(c)

Fig 3-18 Stress-Strain Diagrams for (a) 1 Round Bar 2 Round Bar and (c) 3 Round Bar

Cut-Off Surface

(a)

66

(b)

(c)

Fig 3-19 Cut-Off Surface of (a) 1 Round Bar 2 Round Bar and (c) 3 Round Bar

67

342 SUM 43

Fig 3-20 Untreated SUM 43 Untreated Material

Number 1 5

Hardness(HRB) 76 75

Yield Stress (MPa) 572 594

Tensile Strength (MPa) 743 785

Poissonrsquos Ratio 027 029

Youngrsquos Modulus (GPa) 200 202

Cut-off Area Shrinking () 338 2944

Elongation () 857 894

Table 3-8 Mechanical Properties of SUM 43 Untreated

68

Stress-Strain Diagrams

(a)

(b)

Fig 3-21 Stress-Strain Diagrams for SUM 43 (a) 1 Round Bar and (b) 5 Round Bar

69

Cut-Off Area

(a)

(b)

Fig 3-22 Cut-Off Area of SUM 43 (a) 1 Round Bar and (b) 5 Round Bar

70

SUM 43 Nickel Round Bar

Fig 3-23 SUM 43 Nickel Material

Number 4 5

Hardness(HRB) 51 50

Yield Stress (MPa) 1580 1544

Tensile Strength (MPa) 1639 1625

Poissonrsquos Ratio 03 028

Youngrsquos Modulus (GPa) 194 201

Cut-off Area Shrinking () 1697 137

Elongation () 376 265

Table 3-9 Mechanical Properties of SUM 43 Nickel

71

Stress-Strain Diagrams

(a)

(b)

Fig 3-24 Stress-Strain Diagrams for (a) 4 Round Bar and (b) 5 Round Bar

72

Cut-Off Area

(a)

(b)

Fig 3-25 Cut-Off Area of (a) 4 Round Bar and (b) 5 Round Bar

73

SUM 43 Black Surface Material

Fig 3-26 SUM 43 Black Surface Material

Number 3 5

Hardness(HRB) 56 56

Yield Stress (MPa) 1416 1361

Tensile Strength (MPa) 1591 1402

Poissonrsquos Ratio 029 031

Youngrsquos Modulus (GPa) 200 202

Cut-off Area Shrinking () 139 124

Elongation () 24 24

Table 3-10 Mechanical Properties of SUM 43 Black Surface Material

74

Stress-Strain Diagrams

0 2 4 6 8 10 12 14

-200

0

200

400

600

800

1000

1200

1400

1600

1800

應力 (MPa)

應變()

(a)

0 2 4 6 8 10

-200

0

200

400

600

800

1000

1200

1400

1600

應力

(MPa)

位移 ()

(b)

Fig 3-27 Stress-Strain Diagrams for (a) 3 Round Bar and (b) 5 Round Bar

(Note These curves were formulated using Visual Solutions Inc VisSim Software)

75

Cut-Off Area

(a)

(b)

Fig 3-28 Cut-Off Area of (a) 3 Round Bar and (b) 5 Round Bar

76

The force value (N) was retrieved from the Universal Testing Machine

The Poissonrsquos Ratio (ε) is calculated as

ε =

the values for the Poissonrsquos Ratio are in average around 0297

The Youngrsquos Modulus (E) is calculated as

E =

Where

Stress =

Cross-sectional Area =

where D is the Diameter

The value for D was in average around 1258 mm

The values shown by the computer because there is Slippage phenomena between the Clamp and the

specimen will not be taken into consideration for the elongation strain and Youngrsquos modulus and we will

refer to the values that we have meticulously calculated

77

Chapter 4 AR COATING IN DEPTH

41 Experimentrsquos Purpose and Principles

By means of a vacuum chamber and several other instruments we intend to apply Anti-Reflective

Coating using deposition process to a laser diode and in this way reduce its refraction so as to make it

lose less light in the process of amplification and we can control certain wavelengths we want produced

for certain desired applications in our case we are attempting to re-create a Bose-Einstein Condensate

An optimal BEC apparatus is shown in figure 4-1

Fig 4-1 BEC Apparatus

The main point of this experiment is to build a vacuum chamber system attach all the instrumentation

needed (Vacuum pump deposition meter and voltmeter) and use it to apply AR coating to a laser diode

After we have accomplished the AR coating other team will be in charge of designing the BEC apparatus

and use the results of our research

78

42 Experimentrsquos Equipment

421 Vacuum Chamber

For this research we designed a vacuum chamber whose main body is shown in figure 4-2 Its

dimensions are

Width 240 mm

Length 240 mm

Height 200 mm

Outer Diameter 4 in

Inner Diameter 15 in

Fig 4-2 Vacuum Chamber Main Body

The chamber is made up of 6 pass ways pass way A is the connection with the Laser Deposition

Equipment pass way B is the connection with the Turbo Pump and pass way C is for the connection with

the Deposition Source

A

C

B

79

Pass way C is for the deposition source as mentioned above This is a system where a thermal

resistance is heated by passing a high current through it which heats up a filament boat (made of tungsten)

where the material to be evaporated is place We control the temperature as such that the material will

evaporate and the heat will not cause the filament boat to crack

Because P = Isup2 R (where P is power I is current and R is resistance) to avoid the current to flow

where it is not desired we decided that the material for the Thermocouple shown in figure 4-3 should be

Copper ᴓ 63 mm We choose it that way because Copper has very good heat dissipation characteristics

and the resistance value is low It can reduce the value of the current enough to make the thermocouple to

create heat

Fig 4-3 Thermocouple

To the thermocouple we attach the tungsten filament boat We need to take notice of materials to be

used in this design because when using high current the tungsten filament boar will heat up and so the

material must be able to keep up with the heating potential of tungsten and has a low coefficient of heat

dissipation to avoid the tungsten to fail when heating up and therefore not evaporating Considering all

this we decide to use Stainless Steel

Because this clamp will be assembled inside the chamber after many revisions it was determined it

will have the shape shown in figure 4-4

Fig 4-4 Filament Boat Clamp Design

80

For the tungsten filament boat we bought the product from a distributor The dimensions are

Length 100 mm

Width 10 mm

Height 1 mm

Our thermocouple is 15 in but the pass way C is 4 in so we need to attach a Flange that connects

15in to 4in Because these specifications are quite difficult to achieve by Milling we had to use

electrical wire cutting

For the laser clamping system where the laser that is going to be AR coated will be placed will be

connected to pass way A the assembly is shown in figure 4-5 below

Fig 4-5 Cover Assembly

For this design we used an O-ring instead of a gasket so as to save time The design of the assembly

where the laser will be placed is shown in figure 4-6

Fig 4-6 Upper Cover Inner Assembly

D

E

F

81

Point D is the plate in the assembly where the laser diode will be fixed Because of the easy

processing we decide to use Aluminum and it is screwed to the top cover Point E is the connection for

the Quartz crystal resonator and it is designed in the same as point F in this way the results of the quartz

microbalance system will be more accurate in real time Point F is the final resting place for the laser

diode We use a Thor Labs Base with dimensions of ᴓ 9mm and ᴓ 56mm for two different size laser

diodes It just needs to be plugged in for easy installation

From figure 4-6 we know that the system needs signal system connections and because of the

change in temperature inside the chamber this could affect the functioning of the quartz microbalance so

we also need to install water tubes for cooling This is shown in figure 4-7 below

Fig 4-7 Diagram of Upper Cover Connections

In figure 4-8 we show the Feed through connections and their functions

Fig 4-8 Feed through Diagram

82

1 SQM-160 wire 5 Laser Connection 1 (Vin)

2 SQM-160 (G) 6 Laser Connection 2 (G)

3 K-Type-1 7 Laser Connection 3 (PD)

4 K-Type-2 8 Not In Use

The fully assembled chamber is shown in figure 4-9

Fig 4-9 Fully Assembled Chamber

422 Quartz Crystal Microbalance

For measuring the deposition on our target for coating we used the Inficon SQM-160 RateThickness

Monitor It is an easy to use instrument for measuring many types of thin-film coatings as shown in

figure 4-10

(a) Front Panel (b) Back Panel

Fig 4-10 Inficon SQM-160

83

Table 4-1 shows the technical specifications for this equipment

Number of sensors 2 Standard 4 additional optional

Sensor Frequency Range 40 MHz ~ 60 MHz

Reference Frequency Accuracy 002

Thickness Display Resolution 1 Aring

Thickness Resolution 015 Aring (Std) 0037 Aring (Hi Res)

Density of Stored Films 05-9999 gmcc

Tooling 10-399

Z-Factor 010-1000

Final Thickness 0000-9999k Aring

Measurement Period 15 to 2 sec

Simulation Mode Yes

Frequency Mode Yes

Rate Resolution 011 Arings

Dual Crystal Yes

Etch Mode Yes

Crystal Tooling 10-399

Crystal Fail Min Max 40 to 60 MHz 41 to 61 MHz

Power 100-120 200-240~plusmn10 nominal 20W

Operation Environment 0degC ~ 50degC

0 ~ 80 RH non-condensing

0 ~ 2000 meters

Class 1 Equipment

Pollution Degree 2

Rack Dimensions 885mm x 2127mm x 1969mm

Weight 27 kg

Table 4-1 Inficon SQM-160 RateThickness Monitor Specs

84

To the SQM-160 we need to connect an Oscillator We use the Sigma Instruments Remote Oscillator

Ser No 2 268 as shown in figure 4-11

Fig 4-11 Sigma Instruments Remote Oscillator

The connections diagram is shown in figure 4-12

Fig 4-12 SQM-160 Connections Diagram

85

423 Turbo Pump

For our experiments we used the Pfeiffer TCP 015 Electronic Drive Unit shown below in figure 4-13

Table 4-2 shows the technical specifications for this equipment

(a) Front Panel (b) Back Panel

Fig 4-13 Pfeiffer TCP 015 Electronic Drive

Connection Voltage (100V) 90-112

Mains Frequency 5060 Hz

Start-up Current 22 A

Nominal Frequency 1500 Hz

Rotation Speed 10V = 1500Hz plusmn2

Analog Output Current 10 V = 25 A plusmn 5

Rotation Speed Switchpoint 750 Hz

Works Setting 8 min

Permissible Ambient Temperature 0degC ~ 40degC

Dimensions Front Panel 1285mm x 1063mm

Insertion Length 227mm

Weight 27 Kg

Table 4-2 Pfeiffer TCP 015 Electronic Drive Specs

86

The connections diagram is shown in figure 4-14

Fig 4-14Connections Diagram for Pfeiffer TCP 015

To measure the pressure inside the chamber we use the Granville Phillips 375 Convectron Vacuum

Pressure Controller shown in figure 4-15

(a) Front Panel (b) Back Panel

Fig 4-15 Granville Phillips 375 Convectron

87

Its dimensions are shown in figure 4-16

Fig 4-16 Dimensions of Convectron

Table 4-3 shows the technical specifications for this equipment

Table 4-3 Granville Phillips 375 Convectron Vacuum Pressure Controller Specs

88

424 Multimeter

For our experiment we used the Keithley 2000 Digital Multimeter as shown in figure 4-17

(a) Front Panel (b) Back Panel

Fig 4-17 Keithley Model 2000 6-12-Digit Digital Multimeter

Its technical specifications are shown in table 4-4

Table 4-4 Keithley Model 2000 6-12-Digit Digital Multimeter Specs

89

43 Experiment Procedure

1 Connecting together the equipment and the chamber

(1) We first connect the resonator to the thickness monitor and connect the other side to the

chamber

(2) We now connect the flexible tubes to the turbo pump on one side and to the chamber on the

other

(3) We need to check that tubes are tightly connected to avoid any leaks in the vacuum pumping

process which will not allow us to get to our goal of Torr As shown in figure 4-18

(4) Connect the convectron to the system as shown in figure 4-19

Fig 4-18 checking for leaks using alcohol

Fig 4-19 Convectron attached to System

90

(5) Attach the clamps of the Multimeter to the bottom of the chamber as shown in figure 4-20

(6) Place the Quartz crystal in place

(7) Close tight vacuum chamber

(8) Connect all electrical appliances to power source

Fig 4-20 Multimeter Connections

2 Starting up the System

(1) We turn on all the devices as such Check all systems are ready to function Reset all values

that might be left over from previous tests

(2) Start the thickness monitor and set all values for this experiment In our case we got to testing

the system but not actual coating So we used the simulation mode of the thickness monitor as

shown in figure 4-21

Fig 4-21 Simulation Mode

91

(3) Start the turbo pump Make sure the lid on the vacuum chamber is tightly closed

(4) Start convectron and record initial pressure

(5) Start Multimeter and record initial current

3 Coating Process

(1) If we have the deposition material inside the filament boat the power source for the high

current must be started as well

(2) Record all initial values for thickness current pressure

(3) For an ideal experiment we need a thickness of around 101 nm a pressure of Torr and

a current of 300 A

44 Results

From previous experiments we have shown that we can turn a LED into a laser by means of AR

Coating In figure 4-22 shown below we can compare the actual results of a Diode before and after AR

coating From the blue line we can see that when the diode is at a current of 15mA its light will change

from LED to laser and if we look at the red line its critical current is around 30 to 35 mA

Fig 4-22 AR Coating Comparison for Laser Diodes

This means that the light emitted is not as strong as if the diode had been coated because inside the

chamber there must be some excitation first so the reflectivity of both sides inside the diode must be high

So because of the coating in one of the sides we have opened a door and let the light come out so the

critical current is risen as such and will be higher value than that of before the coating

92

In the following figures we can see the difference between before and after coating in a material The

thickness is around 1016 nm for this material

Fig 4-23 Before Coating

Fig 4-24 After Coating

93

Chapter 5 CONCLUSIONS AND RECOMMENDATIONS

51 Conclusions

For the first part of this independent study taking into consideration the data that came out of our

research and that sent by the provider we can say

1 SUM 23 after heat treatment will unexpectedly develop cracking in the middle of the tensile

testing process and suddenly break

2 Itrsquos possible that in the process of heat treatment to the SUM 23 material the treatment was not

uniform and this will create a pre-loaded moment force on one side that pushes on the other side

of the specimen resulting in material deformation

3 In the process of attaching the strain gauges to the materials it is very easy to make errors due to

poor adhesion or sudden removal in the tensile testing process

For our second part of the independent study the following can be made

1 At the beginning of this independent study we had no idea what Bose-Einstein Condensate was

or what was its purpose After much literature we finally comprehended the basic principles to

put into practice for our research

2 Our systemrsquos basic working principles and equipmentrsquos complexity are a little difficult to grasp

but hopefully we were able to understand enough of it

3 Theoretically from relation between the power and current we can know the advantages and

disadvantages of AR Coating

4 We were able to assemble the system and run test on its functions Even though we were able to

do this there is still much more work left to do with this system

52 Recommendations

For the Tensile Testing the following can be said

1 Ask the provider to check on the process of heat treatment on the SUM 23 material and give

them the information we have gathered through our test so they can correct for the mechanical

properties found if any change is needed

2 To avoid the problem of the inaccuracy of the poor adhesion of strain gauges we can attach

multiple strain gauges to the same one specimen so as to correlate data and improve our results

For the AR Coating the following can be said

1 We need to make sure that there are no physical defects on the main body of the chamber so as to

achieve maximum efficiency in the vacuum process If there was then the vacuum will arrive to

certain point and then start to decrease

2 It would be preferable to add some sort of visual aid that will allow the user to check the inside of

the chamber without actually opening it This will help us determine at what times we should

manipulate the current to better evaporate the substrate

94

REFERENCES

[1] A L Window Strain Gauge Technology Elsevier Applied Science London and New York 2nd

Edition 1992

[2] CC Perry and HR Lissner Strain Gauge Primer McGraw-Hill Book Co Inc New York 1955

[3] James W Dally William F Riley McGraw-Hill 1978

[4] University of Colorado Boulder BEC - What is it and where did the idea come from

httpwwwcoloradoeduphysics2000becwhat_is_ithtml

[5] Ultraslow Light amp Bose-Einstein Condensates Two-way Control with Coherent Light amp Atom

Fields Harvard Hau Lab Dr Lene Vestergaard Hau Optics amp Photonics News 16 1995

[6] The Art of Taming Light Ultra-slow and Stopped Light Harvard Hau Lab Dr Lene

Vestergaard Hau Europhysics News 2004

[7] Nonlinear Optics Shocking Superfluids Harvard Hau Lab Dr Lene Vestergaard Hau Nature

Physics 2007

[8] Model P3 Strain Indicator and Recorder Instruction Manual Vishay Micro-Measurements 2005

[9] Granville-Phillips Series 375 Convectron Vacuum Gauge Controller Instruction Manual Brooks

Automation 2008

[10] Effect of Film Thickness on the Validity of the Sauerbrey Equation for Hydrated Polyelectrolyte

Films Vogt Lin Wu White 2004

[11] Quartz Crystal Microbalance Study of DNA Immobilization and Hybridization for DNA Sensor

Development Chang Zhao 2008

[12] Installation of Strain Gages with SR-4 PrecoatAdhesive Vishay Micro-Measurements 2005

[13] Strain Gauge Measurement ndash A Tutorial National Instruments 1998

[14] Correlation between Vickers Hardness Number and Yield Stress of Cold-Formed Products

Yavuz Tekkaya

[15] httpsenwikipediaorg

Page 13: PC Hinge Materials Testing and AR Laser Diode Coating

13

Two configurations are shown the Littrow Configuration and the Littman-Metcalf

Configuration The Littrow configuration contains a collimating lens and a diffraction grating as

the end mirror The first order diffracted beam provides optical feedback to the laser diode which

has AR Coating The emission wavelength can be turned by rotating the diffraction grating A

disadvantage is that it also changes the direction of the output beam

In the Littman-Metcalf configuration the grating orientation is fixed and an additional mirror

is used to reflect the first order beam back to the laser diode The wavelength can be turned by

rotating that mirror This configuration offers a fixed direction of the output beam and also tends

to exhibit smaller line width as the wavelength selectivity is stronger A disadvantage is that

zero order reflection of the beam reflected by the tuning mirror is lost so that the output power is

less than that of a Littrow laser

13 Methodology

The aim of this research is to find the mechanical properties of materials after being

subjected to tensile testing through finite element analysis observations and determine what

material is best for our purposes taking into consideration the strength and durability of the

material among other properties to find use and applications for the AR coated laser diodes to

further improve the grasp of the Bose-Einstein condensation working principles

14 Organization of the Thesis

The research paper includes five chapters

1 Chapter 1 explains the motivation background objective and methodology of this study

2 Chapter 2 explains the working principles and basic knowledge needed to understand this

study

3 Chapter 3 explains the tensile testing in detail steps methods and results

4 Chapter 4 explains the AR coating in detail steps methods and results

5 Chapter 5 is the conclusions taken from the results shown in chapter 3 and 4 and

recommendations done after arranging and critical thinking

14

Chapter 2 BASICS THEORIES

21 Tensile Testing

After a specimen is tested with the use of tensile testing we can get the Stress-Strain Curve using the

relation between tension and displacement Typical curves are shown in Fig 2-1

(a) Ductile materials (b) Brittle materials

Fig 2-1 Stress-Strain Curve

The curve is unique for each material and is found by recording the amount of deformation at distinct

intervals of tensile or compressive loads Thanks to the use of the Stress-Strain curve we can get very

useful information such as

211 Youngrsquos Modulus (E)

As shown in Fig 2-1 as long as the external load is not greater than the Proportional Limit the Stress

(σ) and Strain (ε) remain as a linear relation fulfilling Hookersquos Law

σ = Eε

The slope is the constant factor the inverse of the modulus of elasticity E also called Youngrsquos

modulus When the external load goes over the proportional limit the stress-strain relationship doesnrsquot

follow the linear relation anymore but the deformation remains flexible When the load is released the

deformation is completely eliminated and the specimen goes back to its original state This is called

15

Elastic Deformation When the external load goes over the Elastic limit only then does the specimen

presents Plastic Deformation This type of deformation which is irreversible even when the load is

removed comes after the material does under elastic deformation so this means the object will first come

part way to its original shape Common metals and ceramics have roughly the same elastic limits

212 Yield Strength and Yield Point

Some materials display very evident yield phenomena while some materials donrsquot as shown in Fig

2-2 After we exceed the elastic limit if we continue to exert load when we arrive to a certain value

which differs under different materials and external conditions there is sudden decrease in stress and this

is called the Yield Strength and can be defined as the stress at which a material begins to deform

plastically using the equation

σyield =

Where P is the tension force and Ao is the original cut-off area

The stress remain at a certain value after the decrease but the strain increases this phenomena can be

easily appreciated when studying the behavior of common Carbon Steel Fig2-2 (a) but most metals (like

Aluminum Copper or High Steel Carbon) donrsquot display this kind of behavior as shown in Fig 2-2 (b)

Arriving to this point is very difficult and the most commonly used method for this is to add a 02 or

0002 offset yield strength to the curve This point is held constant on the strain axis of the curve and

from the 0002 position we draw a straight line parallel to the linear relationship line the point at where

this line and the stress-strain curve intercept is the point we take as the 02 offset yield strength

(a)Evident (b) Non-evident

Fig2-2 Stress-Strain Curve Comparison on Metals

16

213 Ultimate Tensile Strength and Breaking Strength

After materials undergo yield they keep lending strength and hardening phenomena occurs (work

hardening) on the material and the external load increases When it has reached the highest point this is

called the Ultimate Tensile Strength (UTS) as shown in Fig2-1 The UTS is defined as

σUTS =

Where Pmax is the load at the materialrsquos ultimate tensile strength point and Ao is the original cut-off

area For brittle materials the ultimate tensile strength is the most important mechanical property for

ductile materials the ultimate tensile strength is not commonly used for industrial and designing purposes

because upon arriving to this value the material already has forgone great plastic deformation After the

specimen goes through UTS there will be necking phenomena which is a mode of tensile deformation

where relatively large amounts of strain localize disproportionately in a small region of the material It

results from instability during tensile deformation when a materialrsquos cross-sectional area decreases by a

greater proportion than the material strain hardens The specimen continues to elongate until it finally

breaks and the load at this point is called Breaking Strength The breaking strength is defined as the

greatest stress in tension that a material is capable of withstanding without rupture

Where Pf is the load at the materialrsquos breaking strength point and Ao is the original cut-off area

214 Poissonrsquos Ratio (ν)

For elastic deformation when materials are compressed in one direction they tend to expand in the

other two directions perpendicular to the direction of compression This is called the Poissonrsquos Effect

The Poison Ratio is a measure of the Poissonrsquos effect It is the ratio of the fraction of expansion divided

by the fraction of compression for small values of these changes

ν=-

215 Strain Gauge Basic Principles

The strain gauge is a device used to measure the strain of an object Itrsquos an elongated metal resistor

which is attached to the specimen being measured and when the specimen is under strain and starts to

deform the strain gauge will have a change in the resistance With the change in value we can calculate

the elementrsquos strain or elastic modulus and the Poissonrsquos ratio

It takes advantage of the physical property of electrical conductance and its dependence on the

conductorrsquos geometry When the electrical conductor (the specimen being tested) is stretched within the

limits of elasticity such that it does not break or deform plastically it will become narrower and longer

17

which increases the electrical resistance through-out From the measured resistance of the strain gauge

the amount of stress may be inferred by using the relations

R=

Where R is the original resistance value is the electrical resistivity lo is the original length of the

conductor and Ao is the original cross sectional area of the conductor If after the application of tension

the change in length is Δl let the length of the specimen be l = l + Δlo and the tension is the same

through-out So

And the resistance is

The Gauge Factor is the ratio of relative change in electrical resistance to the mechanical strain in

other words it is the relative change in length It is defined as

The strain gauge was invented in 1938 by Edward E Simmons and Arthur C Ruge and the most

common type consists of an insulating flexible backing which supports a metallic foil usually made of a

brass-nickel alloy It is attached to the specimen by a suitable adhesive As the object is deformed the foil

also deforms and this causes the electrical resistance to change Then this is usually measured using a

Wheatstone bridge shown below and is related to the strain by the Gauge Factor

Fig2-3 Basic Structure of Strain Gauge

18

Fig 2-4 Strain gauge attached to Wheatstone bridge

22 Hardness Testing Basic Principles

221 Brinell Scale BHN

The Brinell Scale characterizes the indentation hardness of materials through the scale of penetration

of an indenter loaded on a material specimen The typical test uses a 10mm diameter steel ball as indenter

(usually of value equal to BHN450) with a 29kN force For softer materials smaller force is used The

indentation is measured and BHN is calculated using the relation

BHN =

radic

Where F is the applied force usually within the range of 100 250 500 750 1000 1500 2000 2500

and 3000 kgf D is the diameter of indenter usually within the range of 5mm or 10mm plusmn0005 margin

and d is the diameter of indentation usually around 2mm Its units are of Kgmmsup2 but are not normally

written

First proposed by Swedish engineer Johan August Brinell in 1900 it was the first widely used and

standardized hardness test in engineering and metallurgy although the large size of indentation and

possible damage to specimen limits its usefulness

Fig 2-5 Brinell Indentation Fig2-6 Brinell Hardness Tester

19

222 Rockwell Scale HR

The Rockwell scale is a hardness scale based on the indentation hardness of a material The Rockwell

test determines the hardness by measuring the depth of penetration of an indenter under a large load

compared to the penetration made by a preload The indenter is forced into the specimen under a

preliminary load When equilibrium is reached a measuring device follows the movements of the

indenter and responds to changes in depth of penetration of the indenter While the preload is still being

applied additional major load is applied resulting in increased penetration When equilibrium is reached

again the major load is removed but the preload is maintained Removing the major load allows partial

recovery and reduces the depth of penetration The permanent increase in depth of penetration resulting

from the application and removal of the major load is used to calculate the Rockwell number using the

relation

HR = E ndash e

Where E is a constant depending on the form of the indenter 100 units for diamond indenter and 130

units for steel ball indenter e is the permanent increase in depth of penetration due to the major load

measured in units of 0002mm

Fig 2-7 Rockwell Indentation

When testing materials indentation hardness is related linearly to the tensile strength The important

relation permits economically important nondestructive testing of bulk metal deliveries with lightweight

equipment like the Rockwell tester shown below in figure 2-7

Fig 2-8 Rockwell Hardness Tester

20

There are different scales denoted by a single letter that use different loads or different indenters

The result is a dimensionless number denoted as HR X where X will be the letter denoting the scale as

shown below in table 2-1

Table 2-1 Rockwell Hardness Test Scale

Differential depth hardness measurement was first conceived in 1908 by Viennese professor Paul

Ludwik It eliminated the errors associated with the mechanical imperfections of the system such as

backlash and surface imperfections in the specimen Rockwell testing has an advantage over Brinell

testing because the latter was slow itrsquos not useful on fully hardened steel and left too large an impression

to be considered nondestructive

The tester was co-invented by Hugh M Rockwell and Stanley P Rockwell The requirement for this

tester was to quickly determine the effects of heat treatment on steel bearing races

21

223 Vickers Hardness Test HV

This is a type of microindentation hardness test where a diamond indenter of specific geometry is

impressed into the surface of the test specimen using a known applied force ranging from 10 to 1000

grams This type of tests usually has forces of 2N and produce indentations of about 50μm They can be

used to observe changes in hardness on the microscopic scale It is difficult to standardize the

microhardness measurements because it has been found that the microhardness of almost any material is

higher than its macrohardness The values also vary with load and work-hardening effects of materials

The Vickers test is often easier to use than other hardness tests because the required calculations are

independent of the size of the indenter and the indenter can be used for all materials It can be used for all

metals and has one of the widest scales among hardness tests The unit of the Vickers test is denoted as

HV and can be converted to units of Pascal (Pa) but it is not a measurement of pressure The hardness

number is determined by the load over the surface area of the indentation and not the area normal to the

force

A square-based pyramid shaped diamond is use as the indenter It has been established that the ideal

size of a Brinell impression was 38 of the ball diameter As two tangents to the circle at the ends of a

chord 3d8 long intersect at 136plusmn05deg it was decided to use this as the angle of the indenter giving an

angle to the horizontal plane of 22deg on each side The HV number is determined by the ratio FA where F

is the force applied to the diamond in kgf and A is the surface area of the resulting indentation in mmsup2 A

can be determined by the relation

A =

Where A is the surface area of indentation and d is the average length diagonal left by the indenter

This can be approximated as

A =

Then the Vickers Number is

HV =

=

Vickers hardness number is reported as xxxHVyy or xxxHVyyzz (if duration of applied force differs

from 10s to 15s) where xxx are replaced by the hardness number yy is the load in kg and zz indicates

loading time The values are generally independent of test force

The test was developed in 1921 by Robert L Smith and George E Sandland at Vickers Ltd as an

alternative to Brinell method to measure the hardness of materials

22

Fig 2-9 Vickers Indentation Fig 2-10 Vickers Hardness Tester

23 AR Coating

231 Bose-Einstein Condensate

The Bose-Einstein Condensate or BEC is a state of matter of a dilute gas of bosons cooled to

temperatures very near absolute zero around 0K or -27315degC Under such conditions a large fraction of

the bosons occupy the lowest quantum state where the quantum effects become apparent on a

macroscopic scale This gave birth to the Bose-Einstein Statistics which are the rules that govern the

behavior at this state It is one of the two possible ways in which a collection of indistinguishable particles

may occupy a set of available discrete energy states The aggregation of particles in the same state

accounts for the cohesive streaming of laser light and the frictionless creeping of superfluid helium (an

application discussed later) Bose and Einstein recognized that a collection of identical and

indistinguishable particles can be distributed this way This theory applies only to those particles not

limited to single occupancy of the same state particles that do not obey the Pauli Exclusion Principle

restrictions Such particles are the Bosons named after the statistics that correctly describe their behavior

This phenomenon was first predicted by Satyendra Nath Bose around 1924 when he considered how

groups of photons behave He then asked Albert Einstein for help publishing his discoveries to which

Einstein agreed and gave follow up supporting these findings The resulting efforts became the concept of

a Bose gas governed by the Bose-Einstein Statistics described above Einstein demonstrated that cooling

bosonic atoms to a very low temperature would cause them to condense into the lowest accessible

quantum state resulting in a new form of matter

The first gaseous condensate we produced by Eric Cornell and Carl Wieman at the University of

Colorado at Boulder NIST ndash JILA lab sung a gas of rubidium atoms cooled to 170 nK which earned

them the 2001 Nobel Prize in physics together with Wolfgang Ketterle from MIT The transition to BEC

occurs below a critical temperature which for a uniform three dimensional gas consisting of

non-interacting particles with no apparent internal degrees of freedom is given by

23

Tc =

(

)

asymp 33125

Where Tc is the critical temperature n is the particle density m is the mass per boson h is the

reduced Planck constant k is the Boltzmann constant and ζ is the Riemann zeta function

There are two classes of elementary particles defined by whether their quantum spin is a nonnegative

integer or an odd half integer A Bose-Einstein Condensate is shown below in figure 2-11

Fig 2-11 Bose Einstein Condensate at different scales

Bosons are the particles whose quantum spin is a nonnegative integer (s = 0 1 2 etc) Examples of

bosons include fundamental particles (Higgs Boson Photons W and Z Bosons Gluons Gravitons etc)

composite particles (Mesons Hadrons Nuclei and Atoms of Carbon-12 and Helium-4) and

quasi-particles Bosons are considered force carrier particles The Bosons differ from Fermions in that

there is no limit to the number that can occupy the same quantum state This is called the Pauli Exclusion

Principle

The Pauli Exclusion Principle says that no two identical fermions may occupy the same quantum state

simultaneously in other words this means that the total wave function for two identical fermions is

anti-symmetric with respect to exchange of the particles This means that no two electrons in a single

atom can have the same four quantum numbers

Fermion is any particle characterized by Fermi-Dirac Statistics and follows the Pauli Exclusion

Principle described above Quarks Leptons and composite particles (Hadrons Nuclei and Atoms of

Carbon-13 and Helium-3) made of an odd number of these are considered Fermions It can be an

elementary particle such as the electron or a composite particle such as the protons Following the Pauli

24

Exclusion Principle only one fermion can occupy a particular quantum state at any given time If multiple

fermions have the same spatial probability distribution then at least one property of each fermion must be

different Fermions are usually associated with matter because composite fermions are key building

blocks of matter (neutrons and protons)

Fermionsrsquo behavior by the Fermi-Dirac Statistics which describes the energies of single particles in a

system comprising of many identical particles It applies to identical particles with half-odd integer spin

in a system of thermal equilibrium The particles in the system are assumed to have negligible mutual

interaction This allows the many-particle system to be described in terms of single-particle energy states

The result is the Fermi-Dirac distribution of particles over these states and includes the condition that no

two particles can occupy the same state which has considerable effect on the properties of the system

In quantum mechanics the position of an object is uncertain An object has a definite probability of

being at any given point in space This probability is encoded in the wave function mentioned earlier If

one concentrates a large number of identical bosons in a small region then it is possible for their wave

functions to overlap so much that the bosons lose their identity When this happens thatrsquos a Bose-Einstein

Condensate It is only possible at very low temperatures because at high temperatures the individual

bosons have small wave functions and move rapidly which causes them to fly apart

For now applications are still restricted because there are still some setbacks regarding BECs They

are extremely fragile they are being produced in small quantities with just a few million atoms at a time

and finally they can only be made from certain types of atoms Some examples are the atom laser Ketterle

in which a conventional light lase emits a beam of coherent photons this means they are all in phase and

can be concentrated to an extremely small bright spot BECs can slow down light as demonstrated by

Prof Lene Hau PhD in 2001 by the use of a superfluid [7] These manipulations could develop into

new types of telecommunications technology optical storage and quantum computing

BECs are related to super-fluidity and super-conductivity Super-fluidity is the state of matter in

which the behavior is that of a fluid with zero viscosity It was discovered in liquid helium but now it has

applications in astrophysics high-energy physics and theories of quantum gravity

Super-conductivity is a phenomenon of exactly zero electrical resistance and expulsion of magnetic

fields occurring in certain materials when cooled below a characteristic critical temperature A

super-conductor is shown below in figure 2-12

Fig2-12 Super Conductor

25

232 AR Coating Basic Principles

Anti-reflective (AR) coating is a type of optical coating applied to the surface of lenses and other

optical devices (in our case we planned to apply it to a laser diode) to reduce reflection This improves

the efficiency of the system since less light is lost The primary benefit is the elimination of the reflection

itself

When light the medium (glass) it will produce reflection if 100 of the light comes from the air and

enters the glass because therersquos a difference between the index of refraction some of the light will go out

and when the light is coming out of the glass into the air once again because of the difference between

index of refraction some of the light wonrsquot be able to pass through the medium

When the light makes the first trip into the glass there was a loss of about 4 in the reflection and

when the light makes the trip back outside there was another loss of about 4 so when we assume that

100 of the light interacts with the medium actually therersquos just about 92 acting (we neglect the light

absorbed by the glass around 05) To illustrate this idea please refer to figure 2-13

Fig 2-13 Simple Model for Light in Glass Medium

When we apply the AR Coating the light that enters will only have a loss of about 05 and when

making the trip back outside again only 05 of light is loss so we get the result of increasing the light

passing through up to 99 (again neglecting the light absorbed by the glass around 05) To illustrate

this idea please refer to figure 2-14

26

Fig 2-14 Simple Model for Light in Glass Medium after AR Coating

The AR Coating can reduce reflection of incoming light In the case that light hits perpendicular to

the surface of the medium the intensity of the reflection can be calculated using the Reflection

Coefficient

Where n0 and ns are the refractive indices of the first and second media respectively The value of R

varies from 0 (no reflection) to 1 (all light reflected) and is usually quoted as a percentage

Complementary to R is the transmission coefficient or Transmittance If absorption and scattering are

neglected then the value of Transmittance is always 1-R then if a beam of light with intensity I is

incident on the surface a beam of intensity RI is reflected and a beam with intensity TI is transmitted to

the medium

The optimal value is called the Optimal Index of Refraction and is described as

For glass with ns around 15 in air (n0 around 10) then the optimum refractive index will be n1 =

1225

To reduce the refraction in this case we now mean the one that is produced inside the chamber of the

Laser diode the easiest way is to apply a low reflectivity AR coating on the surface of the laser To

measure the appropriate thickness of the coating layer we can use the equations described above By

applying a coat exactly

thickness film we can assure that a certain wavelength is transmitted The

27

reflected waves from the back of the glass medium will be half a wavelength out of phase So they

interfere destructively Because all reflected waves are interfered the maximum amount of light passes

through the coating Please refer to figure 2-15 to illustrate this idea

Fig 2-15 Light Passing through AR Coat and Glass

The most common process to attain this final product is by vacuum deposition For the best coating

results we need to lower the pressure inside the vacuum system to torr

Fig 2-16 Lens without (Top) and With (Bottom) AR Coating

28

233 Laser Diode Basic Principles

A laser diode is a laser whose active medium is a semiconductor similar to that found in

light-emitting diodes (LEDs) Please refer to figure 2-17 The most common type of laser diode is formed

from a p-n junction and powered by injected electric current

Fig 2-17 Laser Diode

Laser diodes are formed by doping a very thin layer on the surface of a crystal wafer The crystal is

doped to produce the n-type region and a p-type region one above the other

By referring to figure 1-2 we can see the basic structure of a working laser When the laser diode has

a current passing through it the light will get excited inside its gain medium and then will start to

resonate this process is called pumping The current exceeds the critical current and then it comes out as

laser light Please refer to figure 1-3 Since we use an external cavity laser we need to apply the AR

coating to the diode and adjust a diffraction grating The laser light comes out the diode and bounces on

the grating making the resonance externally and this becomes the ldquocavityrdquo as shown in figure 2-18

Fig 2-18 Tunable Laser Basic Configuration

29

The most important feature of the external cavity laser is that we can adjust the wavelength easily just

by changing the diffraction gratingrsquos angle and in the end this is the output wavelength of the laser For

different wavelengths there will be different levels of visible light as shown in figure 2-19

Fig 2-19 Light Spectrum

234 Quartz Microbalance System

A Quartz Crystal Microbalance is an instrument that measures a mass per unit area by measuring the

change in frequency of a quartz crystal resonator The resonance is disturbed by the addition or removal

of a small mass due to oxide growthdecay or film deposition (which is the case in our study) at the

surface of the acoustic resonator The QCM can be used under vacuum in gas phase and more recently in

liquid environments It is useful for monitoring the rate of deposition in thin film deposition systems

under vacuum Frequency measurements are easily made with high precision

For our research we used the Sigma Instruments SQM-160 RateThickness Monitor shown in figure

2-20

Fig 2-20 Front and Back Panels of SQM-160

30

The microbalance uses Quartz as the resonator Quartz is one member of the family of crystals that

experience the Piezoelectric Effect

Piezoelectricity is the charge that accumulates in certain solid materials in response to applied

mechanical stress It means electricity resulting from pressure It was discovered in 1880 by Jacques and

Pierre Curie It is understood as the linear electromechanical interaction between the mechanical and the

electrical state in crystalline materials with no inversion symmetry It is a reversible process in that

materials exhibiting direct piezoelectricity also exhibit the reverse This means that the internal generation

of electrical resulting from applied mechanical force and vice versa

By using the piezoelectric effect we can probe as an acoustic resonance by electrical means Applying

alternating current to the quartz crystal induces oscillations This creates a shear wave We can use these

qualities to determine the resonance frequency at high accuracy

The frequency of oscillation of the crystal is partially dependent in the thickness of the crystal During

normal operation all the variables are held constant so a change in thickness correlates directly to a

change in frequency As mass is deposited or etched away the thickness increases or decreases and so the

frequency of oscillation changes accordingly With some simplifying assumptions the frequency change

can be quantified and correlated precisely to the mass change using the Sauerbreyrsquos Equation

Developed by G Sauerbrey in 1959 it is a method for correlating changes in the oscillation

frequency of a piezoelectric crystal with the mass deposited on it It is defined as below

Where f0 is the Resonant frequency Δf is the Frequency change Δm is the mass change A is the

piezoelectrically active area of the crystal q is the Density of quartz (2648 gcmsup3) and μq is the Shear

modulus of quarts(2947x gcmssup2)

Because the film is treated as an extension of thickness Sauerbreyrsquos equation only applies to systems

in which the following 3 conditions are met

Deposited mass must be rigid

Deposited mass must be distributed evenly

The frequency change

lt002

If the change is greater than 2 the Z-match method must be used to determine the change in mass

It is defined as

Where fL is the frequency of the loaded crystal fU is the resonant frequency Nq is the frequency

constant (1668x HzAring) Δm is the mass change A is the piezoelectrically active area of the crystal

31

q is the density of quartz Z is the method constant f is the density of film μq Is the shear modulus of

quarts and μf is the shear modulus of film

The Sauerbrey equation cannot be applied to systems under liquid medium

The crystals are seed crystals plated with gold on both top and bottom for applications A crystal is

shown in figure 2-21 The QCM consists of a thin piezoelectric plate with electrodes evaporated on both

sides Due to the piezoelectric effect AC voltage across the electrodes induces a shear deformation and

vice versa The electromechanical coupling provides a simple way to detect an acoustic resonance by

electrical means

The Z also called Z-factor is a constant value for different materials and it is shown together with the

density of different materials in table 2-2 below

Fig 2-21 QCM Crystals

The Oscillator of the SQM-160 is shown in figure 2-22 and the equivalent circuit for the Resonant

Oscillator is shown in figure 2-23

Fig 2-22 SQM-160 Oscillator

32

Fig 2-23 Oscillator Circuit

33

Table 2-2 Z-Ratios for Different Materials

Table 2-2 Continued

34

Table 2-2 Continued

35

Table 2-2 Continued

36

Table 2-2 Continued

37

Table 2-2 Continued

38

Table 2-2 Continued

235 Vacuum Chamber System

Vacuum Evaporation is the process of depositing thin films of materials onto surfaces The technique

consists of pumping a vacuum chamber to pressures of less than torr and heating a material to

produce a flux of vapor in order to deposit the material onto a surface The material to be vaporized is

typically heated until its vapor pressure is high enough to produce a flux several Angstrom per second by

using an electrically resistive heater or bombardment by a high voltage beam The process was invented

by Henri Nestle in 1886 for food industry

In here the system has been pumped to a vacuum of Torr When a high current is passed

through the filament boat the filament boat is heated over the desired metal evaporation temperature and

so evaporation starts When the evaporation process is finished and the metal cools down crystals

condensate in the surface of the wafer From the weight of the evaporated material the distance between

the filament boat and the wafer we are able to calculate the deposition thickness and we can also use the

mass detector follower like the Quartz crystal resonator microbalance system In the process of

evaporation we usually use a board in between the filament boat and the wafer This is because before we

arrive to the desired evaporation temperature there will be some impurities that will be vaporized in the

controlled environment so we first use a small current and the board in between to get rid of those

impurities and this raises the purity of the deposition material

39

A vacuum evaporation system is shown in figure 2-24

Fig 2-24 Vacuum Evaporation System

Rough Vacuum 760 ~ 1 torr

Medium Vacuum 1 ~ torr

High Vacuum ~ torr

Ultra-High Vacuum Lower than torr

Table 2-3 Classification of Vacuum

For our study we need to use a Turbo Pump A regular turbo pump is shown in figure 2-25

Fig 2-25 Turbo Pump

For our research we used the Pfeiffer TCP 015 Electronic Drive Unit and Granville Phillips 375

Convectron shown below in figure 2-26

40

Fig 2-26 Control and Measurement Equipment

The electronic drive controls the turbo pump and the Convectron measures the pressure inside our

chamber The turbo pump is a type of vacuum pump used to maintain high vacuum Most turbo pumps

are centrifugal When we start the pumping we need to use a mechanical pump so as to decrease the

pressure inside the system from constant atmospheric pressure to torr and then the use dispersion

pump to continue the vacuum until we get to the desired pressure We need to notice though when we

start the dispersion pump we canrsquot turn off the mechanical pump and they both need to run together If

we need to turn off the pumping we first turn off the dispersion pump wait for it to completely stop and

then turn off the mechanical pump

Our completely assembled system is shown in figure 2-27 below

Fig 2-27 Complete System

41

Chapter 3 TENSILE TESTING IN DEPTH

31 Experimentrsquos Purpose and Principles

By means of Universal testing machine and Strain gauges we were able to observe discuss and

analyze the phenomena created when a specimen of certain material is manipulated under an external load

and determine the stress strain and deformation values later we can use the graphing methods of

stress-strain diagram to describe it

The main point of this experiment is that after the tensile specimen is tested use computer analysis

and the actual strain data and after statistical adjustment make the final results report (Tensile testing

experiment is in accordance with ASTM E8)

32 Experimentrsquos Equipment

321 Universal Testing Machine

For the materials testing experiment part of this research we use a Universal Testing Machine as

shown in figure 31 The maximum load it can apply is 100 Ton After the test specimen is secured on the

device with the use of instrumentation the load exerted and the effects of this become apparent on the

specimen and even the smallest of changes can be recorded For our research we used the Chun Yen

Testing Machines Co Ltd 100 Ton Micro Computer Universal Tensile Tester

Fig 31 Universal Testing Machine

42

Table 31 shows the specifications for this machine

Max Capacity 100 Ton

Accuracy plusmn1

Tension (mm) Max Space 1150mm

Grip for Rod 20-70mm

Ram Stroke 250mm

Effective Column Interval 940mm

Crosshead Speed 300mmmin

Testing Speed 0-50mmmin

Volume of Machine 1700times1000times3350mm(LtimesWtimesH)

Volume of Control Panel 1000times800times1500mm(LtimesWtimesH)

Weight 8000kg

Power 3∮220V 20A

Computer AMD K6-2-350

OS Windows XP

Screen 15rdquo CRT

Table 3-1 Chun Yen Testing Machine Specs Table

The connections diagram is shown in figure 3-2

Fig 3-2 Diagram for System Connections

43

When the test specimen is placed when the external force is applied the Load Cell can measure the

size of the applied force and the Encoder measures the expansion rate of change The Local Controller

receives all the information from the 2 units after arranging the results they are displayed in the

computer and they can be afterwards submitted for more complex analysis such as Finite Element

Analysis and we can get the Stress-Strain Diagram

322 Strain Measurement Equipment

The equipment used in our research provides a four-channel measurement that means we can use up

to 4 strain gauges at a time to do our measurements and provides 3 different bridge arrangements as

shown in figure 3-3

(a) (b) (c)

Fig 3-3 Input Connections for Strain Indicator

Figure 3-3 (a) is the Quarter Bridge (b) is the Half Bridge and (c) is the Full Bridge and Transducers

For our study we used the Quarter Bridge and use the Strain Gauge values to decide the position of the

connecting wires The Strain indicator is shown in figure 3-4

Fig 3-4 Vishay Micro-Measurements Model P3 Strain Indicator and Recorder

44

Input Connections Tool Free eccentric lever release

4-channel input

Wire diameter16-28AWG

Bridge Configurations Quarter- Half- and Full Bridge

Bridge Impedance 60-2000Ω

Display 128 64 pixel FSTN positive gray LCD

Data Conversion AD Converter filter

Measurement Range Resolution Strain Range plusmn155mVV

Resolution plusmn00005mVV

Measurement Accuracy plusmn01 of reading plusmn3 counts

Gage Factor Control 0500-9900

Balance Control Software either manual or automatic

Bridge Excitation 15VDC nominal

Communication Interface USB Cable Included

Data Storage Removable Media Card

Shunt Calibration Across bridge completion resistors controlled

by software When Gage Factor=200

120Ω350Ω1000Ω

Analog Output Value 0 to 25V max

Ranges plusmn320 microε plusmn3200 microε plusmn32000 microε

Error 05 output voltage +5mV

Max Error 14 output voltage + 20mV

Update rate 480 samplessec

Output Load 2000Ω

Power Battery Two Alkaline D cells

Battery life 400 hours typ

USB 5V 100mA

Operational Environment Temperature 0-50

Humidity Up to 90 Non-condensing

Case Aluminum Alloy

Size and Weight 228times152times152(mm) 20(kg)

Table 3-2 Vishay Micro-Measurements Model P3 Strain Indicator and Recorder Specs

45

323 Strain Gauge

The strain gaugersquos main basic principle is to use a resistancersquos characteristics to measure the strain

The inside connections of the strain indicator are shown in figure 3-5

Fig 3-5 Inner Connections

As shown above this is a quarter-bridge connection We connect equal-length 3 wires to the 2

connections allowed by the strain gauge wire 1 and 3 can be used to cancel out the effects of temperature

to the resistance and because of the addition of wires 1 and 3 wire 2 can directly measure the experiment

results from the strain gauge and therefore the strain developed with no influence of temperature

If there were no two measuring leads then the relations will be

R 4 =R g +2R L

Where Rg is the Strain Gauge Value and RL is the wire resistance then

4

4

R

R=

Lg

g

RR

R

2

=

gL

gg

RR

RR

21

amp

4

4

R

R=

g

g

R

R(1- L)

Where L is the Signal Loss Factor and so

L =gL

gL

RR

RR

21

2

g

L

R

2R if

g

L

R

2Rltlt1

46

(Actual Value R g =120R L =08g

L

R

2Ris always much smaller than 1)

R 4 =R g +2R LR 2 =R 3 =rR gR 1 =R g 32 RR =0

V 0 =V 2)1( r

r

(

4

4

R

R-

1

1

R

R)

The first term describes loss attenuation effects second term describes loss of balancing capabilities

effects

V 0 =V 2)1( r

r

[

)2

(Lg

g

RR

R

+

T

Lg

g

RR

R

)

2( + T

Lg

L

RR

R

)

2

2( -(

g

g

R

R) T ]

The first term describes loss attenuation effects and loss of balancing capabilities effects the second

third and fourth terms describe the temperature effects on the wire

For the three-wire method we have

L =gL

gL

RR

RR

1

g

L

R

R if

g

L

R

Rltlt1

V 0 =V 2)1( r

r

[

)(Lg

g

RR

R

+

T

Lg

g

RR

R

)( + T

Lg

L

RR

R

)

2( -

T

Lg

g

RR

R

)( - T

Lg

L

RR

R

)

2( ]

V 0 = V2)1( r

r

)(

Lg

g

RR

R

In the last four terms inside parenthesis we can see the effects of temperature being cancelled out and the

effect on first term is not great so this is the reason why in our research we use three wires

47

324 Specimen Measurements

The tensile specimens used in this research are compliant of ASTM E8 Tensile parameters as shown

in figure 3-6

Fig 3-6 Tensile Specimen

Diameter

D(mm)

Gauge

Length

G(mm)

Smallest

Arc

Radius

R(mm)

Shortest

Area

A(mm)

Total

Length

L(mm)

Clamping

Area

Length

B(mm)

Clamping

Area

Diameter

C(mm)

Bar 125 02 625 01 gt10 gt75 ~ 145 ~ 35 20

Table 3-3 Specifications for Round Bar

33 Experiment Procedure

1 Attaching the Strain Gauge to the Tensile Specimen

(1) Prepare 1 ASTM E8 compliant tensile specimen round bar as shown in figure 3-7

(2) Prepare Strain Gauge as those described in table 3-4

(3) Prepare other consumables and adhesive agent such as epoxy adhesive or

cyanoacrylate adhesive as shown in figure 3-8

48

Fig 3-7 Actual Tensile Specimen

Fig 3-8 Other Materials Used (Such as Alcohol gauze transparent tape adhesive)

Gage Type

EA-06-120LZ-120E

Resistance in ohms at 24∘C

1200plusmn03

Gage Factor at 24∘C

2075plusmn05

Transverse Sensitivity at 24∘C

(+07plusmn02)

Table 3-4 Specifications for Strain Gauge

2 Attaching Strain Gauge

As shown in following figures we shall explain the attachment of the strain gauge

(1) Use sand paper and a rasp to clean thoroughly the surface where the strain gauge will be

attached to

49

(a)

(2) Use alcohol to wash the surface where the strain gauge will be attached and use gauze to rub

it off

(b)

(3) Find a clean surface and clean it with alcohol and gauze

(c)

(4) Place the strain gauge in the clean surface Use a piece of transparent tape on top of the strain

gauge after securely placed rip it off the surface carefully

50

(d)

(5) Use a piece of white paper to mark the place where the strain gauge will be attached and in

this way we can make sure that the strain gauge will be placed as horizontally and vertically

correct as possible

(e)

(6) In the place where we had our mark place the strain gauge

(f)

(7) Carefully lift one side of the tape and apply some of the adhesive agent to both the strain

gauge and specimenrsquos surface

(g)

51

(8) We need to make sure that the gauge and the specimen will be firmly attached so we gently

apply pressure with our thumb

(h)

(9) After the adhesive is fully dry we can carefully rip off the tape

(i)

(10) We need to do the whole process twice one for the horizontally placed strain gauge and one

for the vertically placed strain gauge

52

(j)

(11) We now proceed to solder the wires to the strain gauge

(k)

(12) After soldering we use a Volt Multimeter to measure that there is no contact between wires

If there is none then the specimen is ready for testing

(l)

(13) We now need to measure a 5cm distance and mark it to check and compare the elongation

before and after the tensile testing

(m)

53

Fig 3-9 Specimen-Strain Gauge Process

3 Tensile Test

(1) Enter the computer application that controls the tensile testing machine

(2) Turn on the tensile testing machine main switch

(3) Adjust the hydraulic pump to go back to its original position

(4) Bring the lowering motor down to a distance enough so as to attach the tensile specimen to the

system open the clamps and secure the specimen

(a)

(5) Connect all the necessary wires to the strain indicator equipment

54

(b)

(6) Start the ascending motor and wait for the expansion

(c)

Fig 3-10 Specimen-Tensile Testing Process

4 Start the Test

(1) Enter the software application and enter some variables needed for the experiment in the

specific screen

(2) Go back to the main screen and press the [測試] (measure) button to start the test and auto

recording in the software

(3) After the specimen breaks the mechanical device will automatically stop and ask the user to

enter the total displacement We take out the specimen from the testing machine and adjust the

machinersquos position back to its original position

(4) Save the results information

(5) Record the results from the strain indicator

34 Results

From this experiment we can get the Poissonrsquos Ratio Youngrsquos Modulus and Yield Strength etc and

because of the slippage phenomenon in the clamp at the moment of the test then the Elastic Limit will

display some yield phenomena So omit any undesirable results we just take the Yield portion of the

results as reference

In the process of the experiment the most important part to attend to is the attaching of the strain

gauge because the gaugersquos purpose is to measure the strain developed during the test and this strain

might be very small If the gaugersquos angle change during the test ie is not well attached this will affect

the accuracy of the measurements of Poissonrsquos ratio and Youngrsquos modulus

55

The materials provided by the manufacturer are SUM 23 and SUM 43 steel round bars and these two

types of materials have been through different heat treatment processes so they can be sub-divided

further into untreated material heat-treated material and black surface heat treated material for the two

materials with heat treatment the treatment process and finished are different In the end we only have

the mechanical properties that were calculated after our research of these materials

All of the specifications are identical to those shown in figure 3-6

341 SUM 23

Fig 3-11 SUM 23 Untreated Material

Number 7 10

Hardness(HRB) 74 75

Yield Stress (MPa) 448 440

Tensile Strength (MPa) 544 560

Poissonrsquos Ratio 029 027

Youngrsquos Modulus (GPa) 203 210

Cut-off Area Shrinking () 42 41

Elongation () 1125 1011

Table 3-5 Mechanical Properties of SUM 23 Untreated

56

Stress-Strain Diagram

(a)

(b)

57

Fig 3-12 Stress-Strain Diagrams for (a) 7 Round Bar and (b) 10 Round Bar

Cut-Off Area

(a)

(b)

Fig 3-13 Cut-Off Area of (a) 7 Round Bar and (b) 10 Round Bar

58

SUM 23 Nickel Round Bar

Fig 3-14 SUM 23 Nickel Material

Number 1 2 3 4

Hardness(HRB) 48 50 49 48

Yield Stress (MPa) 370 370 380 400

Tensile Strength (MPa) 455 451 450 450

Poissonrsquos Ratio 028 046 029 026

Youngrsquos Modulus (GPa) 243 303 246 206

Cut-off Area Shrinking () 803 803 726 601

Elongation () 566 65 602 647

Table 3-6 Mechanical Properties of SUM 23 Nickel

59

Stress-Strain Diagram

(a)

60

(b)

(c)

(d)

61

Fig 3-15 Stress-Strain Diagrams for (a) 1 Round Bar (b) 2 Round Bar (c) 3 Round Bar and (d)

4 Round Bar

Cut-Off Area

(a)

(b)

62

(c)

(d)

Fig 3-16 Cut-Off Area of (a) 1 Round Bar (b) 2 Round Bar (c) 3 Round Bar and (d) 4 Round

Bar

63

SUM 23 Black Surface Round Bar

Fig 3-17 SUM 23 Black Surface Material

Number 1 2 3

Hardness(HRB) 51 50 51

Yield Stress (MPa) 378 371 369

Tensile Strength (MPa) 467 465 464

Poissonrsquos Ratio 03 016 04

Youngrsquos Modulus (GPa) 215 266 266

Cut-off Area Shrinking () 986 94 848

Elongation () 748 805 761

Table 3-7 Mechanical Properties of SUM 23 Black Surface Material

64

Stress-Strain Diagram

(a)

(b)

65

(c)

Fig 3-18 Stress-Strain Diagrams for (a) 1 Round Bar 2 Round Bar and (c) 3 Round Bar

Cut-Off Surface

(a)

66

(b)

(c)

Fig 3-19 Cut-Off Surface of (a) 1 Round Bar 2 Round Bar and (c) 3 Round Bar

67

342 SUM 43

Fig 3-20 Untreated SUM 43 Untreated Material

Number 1 5

Hardness(HRB) 76 75

Yield Stress (MPa) 572 594

Tensile Strength (MPa) 743 785

Poissonrsquos Ratio 027 029

Youngrsquos Modulus (GPa) 200 202

Cut-off Area Shrinking () 338 2944

Elongation () 857 894

Table 3-8 Mechanical Properties of SUM 43 Untreated

68

Stress-Strain Diagrams

(a)

(b)

Fig 3-21 Stress-Strain Diagrams for SUM 43 (a) 1 Round Bar and (b) 5 Round Bar

69

Cut-Off Area

(a)

(b)

Fig 3-22 Cut-Off Area of SUM 43 (a) 1 Round Bar and (b) 5 Round Bar

70

SUM 43 Nickel Round Bar

Fig 3-23 SUM 43 Nickel Material

Number 4 5

Hardness(HRB) 51 50

Yield Stress (MPa) 1580 1544

Tensile Strength (MPa) 1639 1625

Poissonrsquos Ratio 03 028

Youngrsquos Modulus (GPa) 194 201

Cut-off Area Shrinking () 1697 137

Elongation () 376 265

Table 3-9 Mechanical Properties of SUM 43 Nickel

71

Stress-Strain Diagrams

(a)

(b)

Fig 3-24 Stress-Strain Diagrams for (a) 4 Round Bar and (b) 5 Round Bar

72

Cut-Off Area

(a)

(b)

Fig 3-25 Cut-Off Area of (a) 4 Round Bar and (b) 5 Round Bar

73

SUM 43 Black Surface Material

Fig 3-26 SUM 43 Black Surface Material

Number 3 5

Hardness(HRB) 56 56

Yield Stress (MPa) 1416 1361

Tensile Strength (MPa) 1591 1402

Poissonrsquos Ratio 029 031

Youngrsquos Modulus (GPa) 200 202

Cut-off Area Shrinking () 139 124

Elongation () 24 24

Table 3-10 Mechanical Properties of SUM 43 Black Surface Material

74

Stress-Strain Diagrams

0 2 4 6 8 10 12 14

-200

0

200

400

600

800

1000

1200

1400

1600

1800

應力 (MPa)

應變()

(a)

0 2 4 6 8 10

-200

0

200

400

600

800

1000

1200

1400

1600

應力

(MPa)

位移 ()

(b)

Fig 3-27 Stress-Strain Diagrams for (a) 3 Round Bar and (b) 5 Round Bar

(Note These curves were formulated using Visual Solutions Inc VisSim Software)

75

Cut-Off Area

(a)

(b)

Fig 3-28 Cut-Off Area of (a) 3 Round Bar and (b) 5 Round Bar

76

The force value (N) was retrieved from the Universal Testing Machine

The Poissonrsquos Ratio (ε) is calculated as

ε =

the values for the Poissonrsquos Ratio are in average around 0297

The Youngrsquos Modulus (E) is calculated as

E =

Where

Stress =

Cross-sectional Area =

where D is the Diameter

The value for D was in average around 1258 mm

The values shown by the computer because there is Slippage phenomena between the Clamp and the

specimen will not be taken into consideration for the elongation strain and Youngrsquos modulus and we will

refer to the values that we have meticulously calculated

77

Chapter 4 AR COATING IN DEPTH

41 Experimentrsquos Purpose and Principles

By means of a vacuum chamber and several other instruments we intend to apply Anti-Reflective

Coating using deposition process to a laser diode and in this way reduce its refraction so as to make it

lose less light in the process of amplification and we can control certain wavelengths we want produced

for certain desired applications in our case we are attempting to re-create a Bose-Einstein Condensate

An optimal BEC apparatus is shown in figure 4-1

Fig 4-1 BEC Apparatus

The main point of this experiment is to build a vacuum chamber system attach all the instrumentation

needed (Vacuum pump deposition meter and voltmeter) and use it to apply AR coating to a laser diode

After we have accomplished the AR coating other team will be in charge of designing the BEC apparatus

and use the results of our research

78

42 Experimentrsquos Equipment

421 Vacuum Chamber

For this research we designed a vacuum chamber whose main body is shown in figure 4-2 Its

dimensions are

Width 240 mm

Length 240 mm

Height 200 mm

Outer Diameter 4 in

Inner Diameter 15 in

Fig 4-2 Vacuum Chamber Main Body

The chamber is made up of 6 pass ways pass way A is the connection with the Laser Deposition

Equipment pass way B is the connection with the Turbo Pump and pass way C is for the connection with

the Deposition Source

A

C

B

79

Pass way C is for the deposition source as mentioned above This is a system where a thermal

resistance is heated by passing a high current through it which heats up a filament boat (made of tungsten)

where the material to be evaporated is place We control the temperature as such that the material will

evaporate and the heat will not cause the filament boat to crack

Because P = Isup2 R (where P is power I is current and R is resistance) to avoid the current to flow

where it is not desired we decided that the material for the Thermocouple shown in figure 4-3 should be

Copper ᴓ 63 mm We choose it that way because Copper has very good heat dissipation characteristics

and the resistance value is low It can reduce the value of the current enough to make the thermocouple to

create heat

Fig 4-3 Thermocouple

To the thermocouple we attach the tungsten filament boat We need to take notice of materials to be

used in this design because when using high current the tungsten filament boar will heat up and so the

material must be able to keep up with the heating potential of tungsten and has a low coefficient of heat

dissipation to avoid the tungsten to fail when heating up and therefore not evaporating Considering all

this we decide to use Stainless Steel

Because this clamp will be assembled inside the chamber after many revisions it was determined it

will have the shape shown in figure 4-4

Fig 4-4 Filament Boat Clamp Design

80

For the tungsten filament boat we bought the product from a distributor The dimensions are

Length 100 mm

Width 10 mm

Height 1 mm

Our thermocouple is 15 in but the pass way C is 4 in so we need to attach a Flange that connects

15in to 4in Because these specifications are quite difficult to achieve by Milling we had to use

electrical wire cutting

For the laser clamping system where the laser that is going to be AR coated will be placed will be

connected to pass way A the assembly is shown in figure 4-5 below

Fig 4-5 Cover Assembly

For this design we used an O-ring instead of a gasket so as to save time The design of the assembly

where the laser will be placed is shown in figure 4-6

Fig 4-6 Upper Cover Inner Assembly

D

E

F

81

Point D is the plate in the assembly where the laser diode will be fixed Because of the easy

processing we decide to use Aluminum and it is screwed to the top cover Point E is the connection for

the Quartz crystal resonator and it is designed in the same as point F in this way the results of the quartz

microbalance system will be more accurate in real time Point F is the final resting place for the laser

diode We use a Thor Labs Base with dimensions of ᴓ 9mm and ᴓ 56mm for two different size laser

diodes It just needs to be plugged in for easy installation

From figure 4-6 we know that the system needs signal system connections and because of the

change in temperature inside the chamber this could affect the functioning of the quartz microbalance so

we also need to install water tubes for cooling This is shown in figure 4-7 below

Fig 4-7 Diagram of Upper Cover Connections

In figure 4-8 we show the Feed through connections and their functions

Fig 4-8 Feed through Diagram

82

1 SQM-160 wire 5 Laser Connection 1 (Vin)

2 SQM-160 (G) 6 Laser Connection 2 (G)

3 K-Type-1 7 Laser Connection 3 (PD)

4 K-Type-2 8 Not In Use

The fully assembled chamber is shown in figure 4-9

Fig 4-9 Fully Assembled Chamber

422 Quartz Crystal Microbalance

For measuring the deposition on our target for coating we used the Inficon SQM-160 RateThickness

Monitor It is an easy to use instrument for measuring many types of thin-film coatings as shown in

figure 4-10

(a) Front Panel (b) Back Panel

Fig 4-10 Inficon SQM-160

83

Table 4-1 shows the technical specifications for this equipment

Number of sensors 2 Standard 4 additional optional

Sensor Frequency Range 40 MHz ~ 60 MHz

Reference Frequency Accuracy 002

Thickness Display Resolution 1 Aring

Thickness Resolution 015 Aring (Std) 0037 Aring (Hi Res)

Density of Stored Films 05-9999 gmcc

Tooling 10-399

Z-Factor 010-1000

Final Thickness 0000-9999k Aring

Measurement Period 15 to 2 sec

Simulation Mode Yes

Frequency Mode Yes

Rate Resolution 011 Arings

Dual Crystal Yes

Etch Mode Yes

Crystal Tooling 10-399

Crystal Fail Min Max 40 to 60 MHz 41 to 61 MHz

Power 100-120 200-240~plusmn10 nominal 20W

Operation Environment 0degC ~ 50degC

0 ~ 80 RH non-condensing

0 ~ 2000 meters

Class 1 Equipment

Pollution Degree 2

Rack Dimensions 885mm x 2127mm x 1969mm

Weight 27 kg

Table 4-1 Inficon SQM-160 RateThickness Monitor Specs

84

To the SQM-160 we need to connect an Oscillator We use the Sigma Instruments Remote Oscillator

Ser No 2 268 as shown in figure 4-11

Fig 4-11 Sigma Instruments Remote Oscillator

The connections diagram is shown in figure 4-12

Fig 4-12 SQM-160 Connections Diagram

85

423 Turbo Pump

For our experiments we used the Pfeiffer TCP 015 Electronic Drive Unit shown below in figure 4-13

Table 4-2 shows the technical specifications for this equipment

(a) Front Panel (b) Back Panel

Fig 4-13 Pfeiffer TCP 015 Electronic Drive

Connection Voltage (100V) 90-112

Mains Frequency 5060 Hz

Start-up Current 22 A

Nominal Frequency 1500 Hz

Rotation Speed 10V = 1500Hz plusmn2

Analog Output Current 10 V = 25 A plusmn 5

Rotation Speed Switchpoint 750 Hz

Works Setting 8 min

Permissible Ambient Temperature 0degC ~ 40degC

Dimensions Front Panel 1285mm x 1063mm

Insertion Length 227mm

Weight 27 Kg

Table 4-2 Pfeiffer TCP 015 Electronic Drive Specs

86

The connections diagram is shown in figure 4-14

Fig 4-14Connections Diagram for Pfeiffer TCP 015

To measure the pressure inside the chamber we use the Granville Phillips 375 Convectron Vacuum

Pressure Controller shown in figure 4-15

(a) Front Panel (b) Back Panel

Fig 4-15 Granville Phillips 375 Convectron

87

Its dimensions are shown in figure 4-16

Fig 4-16 Dimensions of Convectron

Table 4-3 shows the technical specifications for this equipment

Table 4-3 Granville Phillips 375 Convectron Vacuum Pressure Controller Specs

88

424 Multimeter

For our experiment we used the Keithley 2000 Digital Multimeter as shown in figure 4-17

(a) Front Panel (b) Back Panel

Fig 4-17 Keithley Model 2000 6-12-Digit Digital Multimeter

Its technical specifications are shown in table 4-4

Table 4-4 Keithley Model 2000 6-12-Digit Digital Multimeter Specs

89

43 Experiment Procedure

1 Connecting together the equipment and the chamber

(1) We first connect the resonator to the thickness monitor and connect the other side to the

chamber

(2) We now connect the flexible tubes to the turbo pump on one side and to the chamber on the

other

(3) We need to check that tubes are tightly connected to avoid any leaks in the vacuum pumping

process which will not allow us to get to our goal of Torr As shown in figure 4-18

(4) Connect the convectron to the system as shown in figure 4-19

Fig 4-18 checking for leaks using alcohol

Fig 4-19 Convectron attached to System

90

(5) Attach the clamps of the Multimeter to the bottom of the chamber as shown in figure 4-20

(6) Place the Quartz crystal in place

(7) Close tight vacuum chamber

(8) Connect all electrical appliances to power source

Fig 4-20 Multimeter Connections

2 Starting up the System

(1) We turn on all the devices as such Check all systems are ready to function Reset all values

that might be left over from previous tests

(2) Start the thickness monitor and set all values for this experiment In our case we got to testing

the system but not actual coating So we used the simulation mode of the thickness monitor as

shown in figure 4-21

Fig 4-21 Simulation Mode

91

(3) Start the turbo pump Make sure the lid on the vacuum chamber is tightly closed

(4) Start convectron and record initial pressure

(5) Start Multimeter and record initial current

3 Coating Process

(1) If we have the deposition material inside the filament boat the power source for the high

current must be started as well

(2) Record all initial values for thickness current pressure

(3) For an ideal experiment we need a thickness of around 101 nm a pressure of Torr and

a current of 300 A

44 Results

From previous experiments we have shown that we can turn a LED into a laser by means of AR

Coating In figure 4-22 shown below we can compare the actual results of a Diode before and after AR

coating From the blue line we can see that when the diode is at a current of 15mA its light will change

from LED to laser and if we look at the red line its critical current is around 30 to 35 mA

Fig 4-22 AR Coating Comparison for Laser Diodes

This means that the light emitted is not as strong as if the diode had been coated because inside the

chamber there must be some excitation first so the reflectivity of both sides inside the diode must be high

So because of the coating in one of the sides we have opened a door and let the light come out so the

critical current is risen as such and will be higher value than that of before the coating

92

In the following figures we can see the difference between before and after coating in a material The

thickness is around 1016 nm for this material

Fig 4-23 Before Coating

Fig 4-24 After Coating

93

Chapter 5 CONCLUSIONS AND RECOMMENDATIONS

51 Conclusions

For the first part of this independent study taking into consideration the data that came out of our

research and that sent by the provider we can say

1 SUM 23 after heat treatment will unexpectedly develop cracking in the middle of the tensile

testing process and suddenly break

2 Itrsquos possible that in the process of heat treatment to the SUM 23 material the treatment was not

uniform and this will create a pre-loaded moment force on one side that pushes on the other side

of the specimen resulting in material deformation

3 In the process of attaching the strain gauges to the materials it is very easy to make errors due to

poor adhesion or sudden removal in the tensile testing process

For our second part of the independent study the following can be made

1 At the beginning of this independent study we had no idea what Bose-Einstein Condensate was

or what was its purpose After much literature we finally comprehended the basic principles to

put into practice for our research

2 Our systemrsquos basic working principles and equipmentrsquos complexity are a little difficult to grasp

but hopefully we were able to understand enough of it

3 Theoretically from relation between the power and current we can know the advantages and

disadvantages of AR Coating

4 We were able to assemble the system and run test on its functions Even though we were able to

do this there is still much more work left to do with this system

52 Recommendations

For the Tensile Testing the following can be said

1 Ask the provider to check on the process of heat treatment on the SUM 23 material and give

them the information we have gathered through our test so they can correct for the mechanical

properties found if any change is needed

2 To avoid the problem of the inaccuracy of the poor adhesion of strain gauges we can attach

multiple strain gauges to the same one specimen so as to correlate data and improve our results

For the AR Coating the following can be said

1 We need to make sure that there are no physical defects on the main body of the chamber so as to

achieve maximum efficiency in the vacuum process If there was then the vacuum will arrive to

certain point and then start to decrease

2 It would be preferable to add some sort of visual aid that will allow the user to check the inside of

the chamber without actually opening it This will help us determine at what times we should

manipulate the current to better evaporate the substrate

94

REFERENCES

[1] A L Window Strain Gauge Technology Elsevier Applied Science London and New York 2nd

Edition 1992

[2] CC Perry and HR Lissner Strain Gauge Primer McGraw-Hill Book Co Inc New York 1955

[3] James W Dally William F Riley McGraw-Hill 1978

[4] University of Colorado Boulder BEC - What is it and where did the idea come from

httpwwwcoloradoeduphysics2000becwhat_is_ithtml

[5] Ultraslow Light amp Bose-Einstein Condensates Two-way Control with Coherent Light amp Atom

Fields Harvard Hau Lab Dr Lene Vestergaard Hau Optics amp Photonics News 16 1995

[6] The Art of Taming Light Ultra-slow and Stopped Light Harvard Hau Lab Dr Lene

Vestergaard Hau Europhysics News 2004

[7] Nonlinear Optics Shocking Superfluids Harvard Hau Lab Dr Lene Vestergaard Hau Nature

Physics 2007

[8] Model P3 Strain Indicator and Recorder Instruction Manual Vishay Micro-Measurements 2005

[9] Granville-Phillips Series 375 Convectron Vacuum Gauge Controller Instruction Manual Brooks

Automation 2008

[10] Effect of Film Thickness on the Validity of the Sauerbrey Equation for Hydrated Polyelectrolyte

Films Vogt Lin Wu White 2004

[11] Quartz Crystal Microbalance Study of DNA Immobilization and Hybridization for DNA Sensor

Development Chang Zhao 2008

[12] Installation of Strain Gages with SR-4 PrecoatAdhesive Vishay Micro-Measurements 2005

[13] Strain Gauge Measurement ndash A Tutorial National Instruments 1998

[14] Correlation between Vickers Hardness Number and Yield Stress of Cold-Formed Products

Yavuz Tekkaya

[15] httpsenwikipediaorg

Page 14: PC Hinge Materials Testing and AR Laser Diode Coating

14

Chapter 2 BASICS THEORIES

21 Tensile Testing

After a specimen is tested with the use of tensile testing we can get the Stress-Strain Curve using the

relation between tension and displacement Typical curves are shown in Fig 2-1

(a) Ductile materials (b) Brittle materials

Fig 2-1 Stress-Strain Curve

The curve is unique for each material and is found by recording the amount of deformation at distinct

intervals of tensile or compressive loads Thanks to the use of the Stress-Strain curve we can get very

useful information such as

211 Youngrsquos Modulus (E)

As shown in Fig 2-1 as long as the external load is not greater than the Proportional Limit the Stress

(σ) and Strain (ε) remain as a linear relation fulfilling Hookersquos Law

σ = Eε

The slope is the constant factor the inverse of the modulus of elasticity E also called Youngrsquos

modulus When the external load goes over the proportional limit the stress-strain relationship doesnrsquot

follow the linear relation anymore but the deformation remains flexible When the load is released the

deformation is completely eliminated and the specimen goes back to its original state This is called

15

Elastic Deformation When the external load goes over the Elastic limit only then does the specimen

presents Plastic Deformation This type of deformation which is irreversible even when the load is

removed comes after the material does under elastic deformation so this means the object will first come

part way to its original shape Common metals and ceramics have roughly the same elastic limits

212 Yield Strength and Yield Point

Some materials display very evident yield phenomena while some materials donrsquot as shown in Fig

2-2 After we exceed the elastic limit if we continue to exert load when we arrive to a certain value

which differs under different materials and external conditions there is sudden decrease in stress and this

is called the Yield Strength and can be defined as the stress at which a material begins to deform

plastically using the equation

σyield =

Where P is the tension force and Ao is the original cut-off area

The stress remain at a certain value after the decrease but the strain increases this phenomena can be

easily appreciated when studying the behavior of common Carbon Steel Fig2-2 (a) but most metals (like

Aluminum Copper or High Steel Carbon) donrsquot display this kind of behavior as shown in Fig 2-2 (b)

Arriving to this point is very difficult and the most commonly used method for this is to add a 02 or

0002 offset yield strength to the curve This point is held constant on the strain axis of the curve and

from the 0002 position we draw a straight line parallel to the linear relationship line the point at where

this line and the stress-strain curve intercept is the point we take as the 02 offset yield strength

(a)Evident (b) Non-evident

Fig2-2 Stress-Strain Curve Comparison on Metals

16

213 Ultimate Tensile Strength and Breaking Strength

After materials undergo yield they keep lending strength and hardening phenomena occurs (work

hardening) on the material and the external load increases When it has reached the highest point this is

called the Ultimate Tensile Strength (UTS) as shown in Fig2-1 The UTS is defined as

σUTS =

Where Pmax is the load at the materialrsquos ultimate tensile strength point and Ao is the original cut-off

area For brittle materials the ultimate tensile strength is the most important mechanical property for

ductile materials the ultimate tensile strength is not commonly used for industrial and designing purposes

because upon arriving to this value the material already has forgone great plastic deformation After the

specimen goes through UTS there will be necking phenomena which is a mode of tensile deformation

where relatively large amounts of strain localize disproportionately in a small region of the material It

results from instability during tensile deformation when a materialrsquos cross-sectional area decreases by a

greater proportion than the material strain hardens The specimen continues to elongate until it finally

breaks and the load at this point is called Breaking Strength The breaking strength is defined as the

greatest stress in tension that a material is capable of withstanding without rupture

Where Pf is the load at the materialrsquos breaking strength point and Ao is the original cut-off area

214 Poissonrsquos Ratio (ν)

For elastic deformation when materials are compressed in one direction they tend to expand in the

other two directions perpendicular to the direction of compression This is called the Poissonrsquos Effect

The Poison Ratio is a measure of the Poissonrsquos effect It is the ratio of the fraction of expansion divided

by the fraction of compression for small values of these changes

ν=-

215 Strain Gauge Basic Principles

The strain gauge is a device used to measure the strain of an object Itrsquos an elongated metal resistor

which is attached to the specimen being measured and when the specimen is under strain and starts to

deform the strain gauge will have a change in the resistance With the change in value we can calculate

the elementrsquos strain or elastic modulus and the Poissonrsquos ratio

It takes advantage of the physical property of electrical conductance and its dependence on the

conductorrsquos geometry When the electrical conductor (the specimen being tested) is stretched within the

limits of elasticity such that it does not break or deform plastically it will become narrower and longer

17

which increases the electrical resistance through-out From the measured resistance of the strain gauge

the amount of stress may be inferred by using the relations

R=

Where R is the original resistance value is the electrical resistivity lo is the original length of the

conductor and Ao is the original cross sectional area of the conductor If after the application of tension

the change in length is Δl let the length of the specimen be l = l + Δlo and the tension is the same

through-out So

And the resistance is

The Gauge Factor is the ratio of relative change in electrical resistance to the mechanical strain in

other words it is the relative change in length It is defined as

The strain gauge was invented in 1938 by Edward E Simmons and Arthur C Ruge and the most

common type consists of an insulating flexible backing which supports a metallic foil usually made of a

brass-nickel alloy It is attached to the specimen by a suitable adhesive As the object is deformed the foil

also deforms and this causes the electrical resistance to change Then this is usually measured using a

Wheatstone bridge shown below and is related to the strain by the Gauge Factor

Fig2-3 Basic Structure of Strain Gauge

18

Fig 2-4 Strain gauge attached to Wheatstone bridge

22 Hardness Testing Basic Principles

221 Brinell Scale BHN

The Brinell Scale characterizes the indentation hardness of materials through the scale of penetration

of an indenter loaded on a material specimen The typical test uses a 10mm diameter steel ball as indenter

(usually of value equal to BHN450) with a 29kN force For softer materials smaller force is used The

indentation is measured and BHN is calculated using the relation

BHN =

radic

Where F is the applied force usually within the range of 100 250 500 750 1000 1500 2000 2500

and 3000 kgf D is the diameter of indenter usually within the range of 5mm or 10mm plusmn0005 margin

and d is the diameter of indentation usually around 2mm Its units are of Kgmmsup2 but are not normally

written

First proposed by Swedish engineer Johan August Brinell in 1900 it was the first widely used and

standardized hardness test in engineering and metallurgy although the large size of indentation and

possible damage to specimen limits its usefulness

Fig 2-5 Brinell Indentation Fig2-6 Brinell Hardness Tester

19

222 Rockwell Scale HR

The Rockwell scale is a hardness scale based on the indentation hardness of a material The Rockwell

test determines the hardness by measuring the depth of penetration of an indenter under a large load

compared to the penetration made by a preload The indenter is forced into the specimen under a

preliminary load When equilibrium is reached a measuring device follows the movements of the

indenter and responds to changes in depth of penetration of the indenter While the preload is still being

applied additional major load is applied resulting in increased penetration When equilibrium is reached

again the major load is removed but the preload is maintained Removing the major load allows partial

recovery and reduces the depth of penetration The permanent increase in depth of penetration resulting

from the application and removal of the major load is used to calculate the Rockwell number using the

relation

HR = E ndash e

Where E is a constant depending on the form of the indenter 100 units for diamond indenter and 130

units for steel ball indenter e is the permanent increase in depth of penetration due to the major load

measured in units of 0002mm

Fig 2-7 Rockwell Indentation

When testing materials indentation hardness is related linearly to the tensile strength The important

relation permits economically important nondestructive testing of bulk metal deliveries with lightweight

equipment like the Rockwell tester shown below in figure 2-7

Fig 2-8 Rockwell Hardness Tester

20

There are different scales denoted by a single letter that use different loads or different indenters

The result is a dimensionless number denoted as HR X where X will be the letter denoting the scale as

shown below in table 2-1

Table 2-1 Rockwell Hardness Test Scale

Differential depth hardness measurement was first conceived in 1908 by Viennese professor Paul

Ludwik It eliminated the errors associated with the mechanical imperfections of the system such as

backlash and surface imperfections in the specimen Rockwell testing has an advantage over Brinell

testing because the latter was slow itrsquos not useful on fully hardened steel and left too large an impression

to be considered nondestructive

The tester was co-invented by Hugh M Rockwell and Stanley P Rockwell The requirement for this

tester was to quickly determine the effects of heat treatment on steel bearing races

21

223 Vickers Hardness Test HV

This is a type of microindentation hardness test where a diamond indenter of specific geometry is

impressed into the surface of the test specimen using a known applied force ranging from 10 to 1000

grams This type of tests usually has forces of 2N and produce indentations of about 50μm They can be

used to observe changes in hardness on the microscopic scale It is difficult to standardize the

microhardness measurements because it has been found that the microhardness of almost any material is

higher than its macrohardness The values also vary with load and work-hardening effects of materials

The Vickers test is often easier to use than other hardness tests because the required calculations are

independent of the size of the indenter and the indenter can be used for all materials It can be used for all

metals and has one of the widest scales among hardness tests The unit of the Vickers test is denoted as

HV and can be converted to units of Pascal (Pa) but it is not a measurement of pressure The hardness

number is determined by the load over the surface area of the indentation and not the area normal to the

force

A square-based pyramid shaped diamond is use as the indenter It has been established that the ideal

size of a Brinell impression was 38 of the ball diameter As two tangents to the circle at the ends of a

chord 3d8 long intersect at 136plusmn05deg it was decided to use this as the angle of the indenter giving an

angle to the horizontal plane of 22deg on each side The HV number is determined by the ratio FA where F

is the force applied to the diamond in kgf and A is the surface area of the resulting indentation in mmsup2 A

can be determined by the relation

A =

Where A is the surface area of indentation and d is the average length diagonal left by the indenter

This can be approximated as

A =

Then the Vickers Number is

HV =

=

Vickers hardness number is reported as xxxHVyy or xxxHVyyzz (if duration of applied force differs

from 10s to 15s) where xxx are replaced by the hardness number yy is the load in kg and zz indicates

loading time The values are generally independent of test force

The test was developed in 1921 by Robert L Smith and George E Sandland at Vickers Ltd as an

alternative to Brinell method to measure the hardness of materials

22

Fig 2-9 Vickers Indentation Fig 2-10 Vickers Hardness Tester

23 AR Coating

231 Bose-Einstein Condensate

The Bose-Einstein Condensate or BEC is a state of matter of a dilute gas of bosons cooled to

temperatures very near absolute zero around 0K or -27315degC Under such conditions a large fraction of

the bosons occupy the lowest quantum state where the quantum effects become apparent on a

macroscopic scale This gave birth to the Bose-Einstein Statistics which are the rules that govern the

behavior at this state It is one of the two possible ways in which a collection of indistinguishable particles

may occupy a set of available discrete energy states The aggregation of particles in the same state

accounts for the cohesive streaming of laser light and the frictionless creeping of superfluid helium (an

application discussed later) Bose and Einstein recognized that a collection of identical and

indistinguishable particles can be distributed this way This theory applies only to those particles not

limited to single occupancy of the same state particles that do not obey the Pauli Exclusion Principle

restrictions Such particles are the Bosons named after the statistics that correctly describe their behavior

This phenomenon was first predicted by Satyendra Nath Bose around 1924 when he considered how

groups of photons behave He then asked Albert Einstein for help publishing his discoveries to which

Einstein agreed and gave follow up supporting these findings The resulting efforts became the concept of

a Bose gas governed by the Bose-Einstein Statistics described above Einstein demonstrated that cooling

bosonic atoms to a very low temperature would cause them to condense into the lowest accessible

quantum state resulting in a new form of matter

The first gaseous condensate we produced by Eric Cornell and Carl Wieman at the University of

Colorado at Boulder NIST ndash JILA lab sung a gas of rubidium atoms cooled to 170 nK which earned

them the 2001 Nobel Prize in physics together with Wolfgang Ketterle from MIT The transition to BEC

occurs below a critical temperature which for a uniform three dimensional gas consisting of

non-interacting particles with no apparent internal degrees of freedom is given by

23

Tc =

(

)

asymp 33125

Where Tc is the critical temperature n is the particle density m is the mass per boson h is the

reduced Planck constant k is the Boltzmann constant and ζ is the Riemann zeta function

There are two classes of elementary particles defined by whether their quantum spin is a nonnegative

integer or an odd half integer A Bose-Einstein Condensate is shown below in figure 2-11

Fig 2-11 Bose Einstein Condensate at different scales

Bosons are the particles whose quantum spin is a nonnegative integer (s = 0 1 2 etc) Examples of

bosons include fundamental particles (Higgs Boson Photons W and Z Bosons Gluons Gravitons etc)

composite particles (Mesons Hadrons Nuclei and Atoms of Carbon-12 and Helium-4) and

quasi-particles Bosons are considered force carrier particles The Bosons differ from Fermions in that

there is no limit to the number that can occupy the same quantum state This is called the Pauli Exclusion

Principle

The Pauli Exclusion Principle says that no two identical fermions may occupy the same quantum state

simultaneously in other words this means that the total wave function for two identical fermions is

anti-symmetric with respect to exchange of the particles This means that no two electrons in a single

atom can have the same four quantum numbers

Fermion is any particle characterized by Fermi-Dirac Statistics and follows the Pauli Exclusion

Principle described above Quarks Leptons and composite particles (Hadrons Nuclei and Atoms of

Carbon-13 and Helium-3) made of an odd number of these are considered Fermions It can be an

elementary particle such as the electron or a composite particle such as the protons Following the Pauli

24

Exclusion Principle only one fermion can occupy a particular quantum state at any given time If multiple

fermions have the same spatial probability distribution then at least one property of each fermion must be

different Fermions are usually associated with matter because composite fermions are key building

blocks of matter (neutrons and protons)

Fermionsrsquo behavior by the Fermi-Dirac Statistics which describes the energies of single particles in a

system comprising of many identical particles It applies to identical particles with half-odd integer spin

in a system of thermal equilibrium The particles in the system are assumed to have negligible mutual

interaction This allows the many-particle system to be described in terms of single-particle energy states

The result is the Fermi-Dirac distribution of particles over these states and includes the condition that no

two particles can occupy the same state which has considerable effect on the properties of the system

In quantum mechanics the position of an object is uncertain An object has a definite probability of

being at any given point in space This probability is encoded in the wave function mentioned earlier If

one concentrates a large number of identical bosons in a small region then it is possible for their wave

functions to overlap so much that the bosons lose their identity When this happens thatrsquos a Bose-Einstein

Condensate It is only possible at very low temperatures because at high temperatures the individual

bosons have small wave functions and move rapidly which causes them to fly apart

For now applications are still restricted because there are still some setbacks regarding BECs They

are extremely fragile they are being produced in small quantities with just a few million atoms at a time

and finally they can only be made from certain types of atoms Some examples are the atom laser Ketterle

in which a conventional light lase emits a beam of coherent photons this means they are all in phase and

can be concentrated to an extremely small bright spot BECs can slow down light as demonstrated by

Prof Lene Hau PhD in 2001 by the use of a superfluid [7] These manipulations could develop into

new types of telecommunications technology optical storage and quantum computing

BECs are related to super-fluidity and super-conductivity Super-fluidity is the state of matter in

which the behavior is that of a fluid with zero viscosity It was discovered in liquid helium but now it has

applications in astrophysics high-energy physics and theories of quantum gravity

Super-conductivity is a phenomenon of exactly zero electrical resistance and expulsion of magnetic

fields occurring in certain materials when cooled below a characteristic critical temperature A

super-conductor is shown below in figure 2-12

Fig2-12 Super Conductor

25

232 AR Coating Basic Principles

Anti-reflective (AR) coating is a type of optical coating applied to the surface of lenses and other

optical devices (in our case we planned to apply it to a laser diode) to reduce reflection This improves

the efficiency of the system since less light is lost The primary benefit is the elimination of the reflection

itself

When light the medium (glass) it will produce reflection if 100 of the light comes from the air and

enters the glass because therersquos a difference between the index of refraction some of the light will go out

and when the light is coming out of the glass into the air once again because of the difference between

index of refraction some of the light wonrsquot be able to pass through the medium

When the light makes the first trip into the glass there was a loss of about 4 in the reflection and

when the light makes the trip back outside there was another loss of about 4 so when we assume that

100 of the light interacts with the medium actually therersquos just about 92 acting (we neglect the light

absorbed by the glass around 05) To illustrate this idea please refer to figure 2-13

Fig 2-13 Simple Model for Light in Glass Medium

When we apply the AR Coating the light that enters will only have a loss of about 05 and when

making the trip back outside again only 05 of light is loss so we get the result of increasing the light

passing through up to 99 (again neglecting the light absorbed by the glass around 05) To illustrate

this idea please refer to figure 2-14

26

Fig 2-14 Simple Model for Light in Glass Medium after AR Coating

The AR Coating can reduce reflection of incoming light In the case that light hits perpendicular to

the surface of the medium the intensity of the reflection can be calculated using the Reflection

Coefficient

Where n0 and ns are the refractive indices of the first and second media respectively The value of R

varies from 0 (no reflection) to 1 (all light reflected) and is usually quoted as a percentage

Complementary to R is the transmission coefficient or Transmittance If absorption and scattering are

neglected then the value of Transmittance is always 1-R then if a beam of light with intensity I is

incident on the surface a beam of intensity RI is reflected and a beam with intensity TI is transmitted to

the medium

The optimal value is called the Optimal Index of Refraction and is described as

For glass with ns around 15 in air (n0 around 10) then the optimum refractive index will be n1 =

1225

To reduce the refraction in this case we now mean the one that is produced inside the chamber of the

Laser diode the easiest way is to apply a low reflectivity AR coating on the surface of the laser To

measure the appropriate thickness of the coating layer we can use the equations described above By

applying a coat exactly

thickness film we can assure that a certain wavelength is transmitted The

27

reflected waves from the back of the glass medium will be half a wavelength out of phase So they

interfere destructively Because all reflected waves are interfered the maximum amount of light passes

through the coating Please refer to figure 2-15 to illustrate this idea

Fig 2-15 Light Passing through AR Coat and Glass

The most common process to attain this final product is by vacuum deposition For the best coating

results we need to lower the pressure inside the vacuum system to torr

Fig 2-16 Lens without (Top) and With (Bottom) AR Coating

28

233 Laser Diode Basic Principles

A laser diode is a laser whose active medium is a semiconductor similar to that found in

light-emitting diodes (LEDs) Please refer to figure 2-17 The most common type of laser diode is formed

from a p-n junction and powered by injected electric current

Fig 2-17 Laser Diode

Laser diodes are formed by doping a very thin layer on the surface of a crystal wafer The crystal is

doped to produce the n-type region and a p-type region one above the other

By referring to figure 1-2 we can see the basic structure of a working laser When the laser diode has

a current passing through it the light will get excited inside its gain medium and then will start to

resonate this process is called pumping The current exceeds the critical current and then it comes out as

laser light Please refer to figure 1-3 Since we use an external cavity laser we need to apply the AR

coating to the diode and adjust a diffraction grating The laser light comes out the diode and bounces on

the grating making the resonance externally and this becomes the ldquocavityrdquo as shown in figure 2-18

Fig 2-18 Tunable Laser Basic Configuration

29

The most important feature of the external cavity laser is that we can adjust the wavelength easily just

by changing the diffraction gratingrsquos angle and in the end this is the output wavelength of the laser For

different wavelengths there will be different levels of visible light as shown in figure 2-19

Fig 2-19 Light Spectrum

234 Quartz Microbalance System

A Quartz Crystal Microbalance is an instrument that measures a mass per unit area by measuring the

change in frequency of a quartz crystal resonator The resonance is disturbed by the addition or removal

of a small mass due to oxide growthdecay or film deposition (which is the case in our study) at the

surface of the acoustic resonator The QCM can be used under vacuum in gas phase and more recently in

liquid environments It is useful for monitoring the rate of deposition in thin film deposition systems

under vacuum Frequency measurements are easily made with high precision

For our research we used the Sigma Instruments SQM-160 RateThickness Monitor shown in figure

2-20

Fig 2-20 Front and Back Panels of SQM-160

30

The microbalance uses Quartz as the resonator Quartz is one member of the family of crystals that

experience the Piezoelectric Effect

Piezoelectricity is the charge that accumulates in certain solid materials in response to applied

mechanical stress It means electricity resulting from pressure It was discovered in 1880 by Jacques and

Pierre Curie It is understood as the linear electromechanical interaction between the mechanical and the

electrical state in crystalline materials with no inversion symmetry It is a reversible process in that

materials exhibiting direct piezoelectricity also exhibit the reverse This means that the internal generation

of electrical resulting from applied mechanical force and vice versa

By using the piezoelectric effect we can probe as an acoustic resonance by electrical means Applying

alternating current to the quartz crystal induces oscillations This creates a shear wave We can use these

qualities to determine the resonance frequency at high accuracy

The frequency of oscillation of the crystal is partially dependent in the thickness of the crystal During

normal operation all the variables are held constant so a change in thickness correlates directly to a

change in frequency As mass is deposited or etched away the thickness increases or decreases and so the

frequency of oscillation changes accordingly With some simplifying assumptions the frequency change

can be quantified and correlated precisely to the mass change using the Sauerbreyrsquos Equation

Developed by G Sauerbrey in 1959 it is a method for correlating changes in the oscillation

frequency of a piezoelectric crystal with the mass deposited on it It is defined as below

Where f0 is the Resonant frequency Δf is the Frequency change Δm is the mass change A is the

piezoelectrically active area of the crystal q is the Density of quartz (2648 gcmsup3) and μq is the Shear

modulus of quarts(2947x gcmssup2)

Because the film is treated as an extension of thickness Sauerbreyrsquos equation only applies to systems

in which the following 3 conditions are met

Deposited mass must be rigid

Deposited mass must be distributed evenly

The frequency change

lt002

If the change is greater than 2 the Z-match method must be used to determine the change in mass

It is defined as

Where fL is the frequency of the loaded crystal fU is the resonant frequency Nq is the frequency

constant (1668x HzAring) Δm is the mass change A is the piezoelectrically active area of the crystal

31

q is the density of quartz Z is the method constant f is the density of film μq Is the shear modulus of

quarts and μf is the shear modulus of film

The Sauerbrey equation cannot be applied to systems under liquid medium

The crystals are seed crystals plated with gold on both top and bottom for applications A crystal is

shown in figure 2-21 The QCM consists of a thin piezoelectric plate with electrodes evaporated on both

sides Due to the piezoelectric effect AC voltage across the electrodes induces a shear deformation and

vice versa The electromechanical coupling provides a simple way to detect an acoustic resonance by

electrical means

The Z also called Z-factor is a constant value for different materials and it is shown together with the

density of different materials in table 2-2 below

Fig 2-21 QCM Crystals

The Oscillator of the SQM-160 is shown in figure 2-22 and the equivalent circuit for the Resonant

Oscillator is shown in figure 2-23

Fig 2-22 SQM-160 Oscillator

32

Fig 2-23 Oscillator Circuit

33

Table 2-2 Z-Ratios for Different Materials

Table 2-2 Continued

34

Table 2-2 Continued

35

Table 2-2 Continued

36

Table 2-2 Continued

37

Table 2-2 Continued

38

Table 2-2 Continued

235 Vacuum Chamber System

Vacuum Evaporation is the process of depositing thin films of materials onto surfaces The technique

consists of pumping a vacuum chamber to pressures of less than torr and heating a material to

produce a flux of vapor in order to deposit the material onto a surface The material to be vaporized is

typically heated until its vapor pressure is high enough to produce a flux several Angstrom per second by

using an electrically resistive heater or bombardment by a high voltage beam The process was invented

by Henri Nestle in 1886 for food industry

In here the system has been pumped to a vacuum of Torr When a high current is passed

through the filament boat the filament boat is heated over the desired metal evaporation temperature and

so evaporation starts When the evaporation process is finished and the metal cools down crystals

condensate in the surface of the wafer From the weight of the evaporated material the distance between

the filament boat and the wafer we are able to calculate the deposition thickness and we can also use the

mass detector follower like the Quartz crystal resonator microbalance system In the process of

evaporation we usually use a board in between the filament boat and the wafer This is because before we

arrive to the desired evaporation temperature there will be some impurities that will be vaporized in the

controlled environment so we first use a small current and the board in between to get rid of those

impurities and this raises the purity of the deposition material

39

A vacuum evaporation system is shown in figure 2-24

Fig 2-24 Vacuum Evaporation System

Rough Vacuum 760 ~ 1 torr

Medium Vacuum 1 ~ torr

High Vacuum ~ torr

Ultra-High Vacuum Lower than torr

Table 2-3 Classification of Vacuum

For our study we need to use a Turbo Pump A regular turbo pump is shown in figure 2-25

Fig 2-25 Turbo Pump

For our research we used the Pfeiffer TCP 015 Electronic Drive Unit and Granville Phillips 375

Convectron shown below in figure 2-26

40

Fig 2-26 Control and Measurement Equipment

The electronic drive controls the turbo pump and the Convectron measures the pressure inside our

chamber The turbo pump is a type of vacuum pump used to maintain high vacuum Most turbo pumps

are centrifugal When we start the pumping we need to use a mechanical pump so as to decrease the

pressure inside the system from constant atmospheric pressure to torr and then the use dispersion

pump to continue the vacuum until we get to the desired pressure We need to notice though when we

start the dispersion pump we canrsquot turn off the mechanical pump and they both need to run together If

we need to turn off the pumping we first turn off the dispersion pump wait for it to completely stop and

then turn off the mechanical pump

Our completely assembled system is shown in figure 2-27 below

Fig 2-27 Complete System

41

Chapter 3 TENSILE TESTING IN DEPTH

31 Experimentrsquos Purpose and Principles

By means of Universal testing machine and Strain gauges we were able to observe discuss and

analyze the phenomena created when a specimen of certain material is manipulated under an external load

and determine the stress strain and deformation values later we can use the graphing methods of

stress-strain diagram to describe it

The main point of this experiment is that after the tensile specimen is tested use computer analysis

and the actual strain data and after statistical adjustment make the final results report (Tensile testing

experiment is in accordance with ASTM E8)

32 Experimentrsquos Equipment

321 Universal Testing Machine

For the materials testing experiment part of this research we use a Universal Testing Machine as

shown in figure 31 The maximum load it can apply is 100 Ton After the test specimen is secured on the

device with the use of instrumentation the load exerted and the effects of this become apparent on the

specimen and even the smallest of changes can be recorded For our research we used the Chun Yen

Testing Machines Co Ltd 100 Ton Micro Computer Universal Tensile Tester

Fig 31 Universal Testing Machine

42

Table 31 shows the specifications for this machine

Max Capacity 100 Ton

Accuracy plusmn1

Tension (mm) Max Space 1150mm

Grip for Rod 20-70mm

Ram Stroke 250mm

Effective Column Interval 940mm

Crosshead Speed 300mmmin

Testing Speed 0-50mmmin

Volume of Machine 1700times1000times3350mm(LtimesWtimesH)

Volume of Control Panel 1000times800times1500mm(LtimesWtimesH)

Weight 8000kg

Power 3∮220V 20A

Computer AMD K6-2-350

OS Windows XP

Screen 15rdquo CRT

Table 3-1 Chun Yen Testing Machine Specs Table

The connections diagram is shown in figure 3-2

Fig 3-2 Diagram for System Connections

43

When the test specimen is placed when the external force is applied the Load Cell can measure the

size of the applied force and the Encoder measures the expansion rate of change The Local Controller

receives all the information from the 2 units after arranging the results they are displayed in the

computer and they can be afterwards submitted for more complex analysis such as Finite Element

Analysis and we can get the Stress-Strain Diagram

322 Strain Measurement Equipment

The equipment used in our research provides a four-channel measurement that means we can use up

to 4 strain gauges at a time to do our measurements and provides 3 different bridge arrangements as

shown in figure 3-3

(a) (b) (c)

Fig 3-3 Input Connections for Strain Indicator

Figure 3-3 (a) is the Quarter Bridge (b) is the Half Bridge and (c) is the Full Bridge and Transducers

For our study we used the Quarter Bridge and use the Strain Gauge values to decide the position of the

connecting wires The Strain indicator is shown in figure 3-4

Fig 3-4 Vishay Micro-Measurements Model P3 Strain Indicator and Recorder

44

Input Connections Tool Free eccentric lever release

4-channel input

Wire diameter16-28AWG

Bridge Configurations Quarter- Half- and Full Bridge

Bridge Impedance 60-2000Ω

Display 128 64 pixel FSTN positive gray LCD

Data Conversion AD Converter filter

Measurement Range Resolution Strain Range plusmn155mVV

Resolution plusmn00005mVV

Measurement Accuracy plusmn01 of reading plusmn3 counts

Gage Factor Control 0500-9900

Balance Control Software either manual or automatic

Bridge Excitation 15VDC nominal

Communication Interface USB Cable Included

Data Storage Removable Media Card

Shunt Calibration Across bridge completion resistors controlled

by software When Gage Factor=200

120Ω350Ω1000Ω

Analog Output Value 0 to 25V max

Ranges plusmn320 microε plusmn3200 microε plusmn32000 microε

Error 05 output voltage +5mV

Max Error 14 output voltage + 20mV

Update rate 480 samplessec

Output Load 2000Ω

Power Battery Two Alkaline D cells

Battery life 400 hours typ

USB 5V 100mA

Operational Environment Temperature 0-50

Humidity Up to 90 Non-condensing

Case Aluminum Alloy

Size and Weight 228times152times152(mm) 20(kg)

Table 3-2 Vishay Micro-Measurements Model P3 Strain Indicator and Recorder Specs

45

323 Strain Gauge

The strain gaugersquos main basic principle is to use a resistancersquos characteristics to measure the strain

The inside connections of the strain indicator are shown in figure 3-5

Fig 3-5 Inner Connections

As shown above this is a quarter-bridge connection We connect equal-length 3 wires to the 2

connections allowed by the strain gauge wire 1 and 3 can be used to cancel out the effects of temperature

to the resistance and because of the addition of wires 1 and 3 wire 2 can directly measure the experiment

results from the strain gauge and therefore the strain developed with no influence of temperature

If there were no two measuring leads then the relations will be

R 4 =R g +2R L

Where Rg is the Strain Gauge Value and RL is the wire resistance then

4

4

R

R=

Lg

g

RR

R

2

=

gL

gg

RR

RR

21

amp

4

4

R

R=

g

g

R

R(1- L)

Where L is the Signal Loss Factor and so

L =gL

gL

RR

RR

21

2

g

L

R

2R if

g

L

R

2Rltlt1

46

(Actual Value R g =120R L =08g

L

R

2Ris always much smaller than 1)

R 4 =R g +2R LR 2 =R 3 =rR gR 1 =R g 32 RR =0

V 0 =V 2)1( r

r

(

4

4

R

R-

1

1

R

R)

The first term describes loss attenuation effects second term describes loss of balancing capabilities

effects

V 0 =V 2)1( r

r

[

)2

(Lg

g

RR

R

+

T

Lg

g

RR

R

)

2( + T

Lg

L

RR

R

)

2

2( -(

g

g

R

R) T ]

The first term describes loss attenuation effects and loss of balancing capabilities effects the second

third and fourth terms describe the temperature effects on the wire

For the three-wire method we have

L =gL

gL

RR

RR

1

g

L

R

R if

g

L

R

Rltlt1

V 0 =V 2)1( r

r

[

)(Lg

g

RR

R

+

T

Lg

g

RR

R

)( + T

Lg

L

RR

R

)

2( -

T

Lg

g

RR

R

)( - T

Lg

L

RR

R

)

2( ]

V 0 = V2)1( r

r

)(

Lg

g

RR

R

In the last four terms inside parenthesis we can see the effects of temperature being cancelled out and the

effect on first term is not great so this is the reason why in our research we use three wires

47

324 Specimen Measurements

The tensile specimens used in this research are compliant of ASTM E8 Tensile parameters as shown

in figure 3-6

Fig 3-6 Tensile Specimen

Diameter

D(mm)

Gauge

Length

G(mm)

Smallest

Arc

Radius

R(mm)

Shortest

Area

A(mm)

Total

Length

L(mm)

Clamping

Area

Length

B(mm)

Clamping

Area

Diameter

C(mm)

Bar 125 02 625 01 gt10 gt75 ~ 145 ~ 35 20

Table 3-3 Specifications for Round Bar

33 Experiment Procedure

1 Attaching the Strain Gauge to the Tensile Specimen

(1) Prepare 1 ASTM E8 compliant tensile specimen round bar as shown in figure 3-7

(2) Prepare Strain Gauge as those described in table 3-4

(3) Prepare other consumables and adhesive agent such as epoxy adhesive or

cyanoacrylate adhesive as shown in figure 3-8

48

Fig 3-7 Actual Tensile Specimen

Fig 3-8 Other Materials Used (Such as Alcohol gauze transparent tape adhesive)

Gage Type

EA-06-120LZ-120E

Resistance in ohms at 24∘C

1200plusmn03

Gage Factor at 24∘C

2075plusmn05

Transverse Sensitivity at 24∘C

(+07plusmn02)

Table 3-4 Specifications for Strain Gauge

2 Attaching Strain Gauge

As shown in following figures we shall explain the attachment of the strain gauge

(1) Use sand paper and a rasp to clean thoroughly the surface where the strain gauge will be

attached to

49

(a)

(2) Use alcohol to wash the surface where the strain gauge will be attached and use gauze to rub

it off

(b)

(3) Find a clean surface and clean it with alcohol and gauze

(c)

(4) Place the strain gauge in the clean surface Use a piece of transparent tape on top of the strain

gauge after securely placed rip it off the surface carefully

50

(d)

(5) Use a piece of white paper to mark the place where the strain gauge will be attached and in

this way we can make sure that the strain gauge will be placed as horizontally and vertically

correct as possible

(e)

(6) In the place where we had our mark place the strain gauge

(f)

(7) Carefully lift one side of the tape and apply some of the adhesive agent to both the strain

gauge and specimenrsquos surface

(g)

51

(8) We need to make sure that the gauge and the specimen will be firmly attached so we gently

apply pressure with our thumb

(h)

(9) After the adhesive is fully dry we can carefully rip off the tape

(i)

(10) We need to do the whole process twice one for the horizontally placed strain gauge and one

for the vertically placed strain gauge

52

(j)

(11) We now proceed to solder the wires to the strain gauge

(k)

(12) After soldering we use a Volt Multimeter to measure that there is no contact between wires

If there is none then the specimen is ready for testing

(l)

(13) We now need to measure a 5cm distance and mark it to check and compare the elongation

before and after the tensile testing

(m)

53

Fig 3-9 Specimen-Strain Gauge Process

3 Tensile Test

(1) Enter the computer application that controls the tensile testing machine

(2) Turn on the tensile testing machine main switch

(3) Adjust the hydraulic pump to go back to its original position

(4) Bring the lowering motor down to a distance enough so as to attach the tensile specimen to the

system open the clamps and secure the specimen

(a)

(5) Connect all the necessary wires to the strain indicator equipment

54

(b)

(6) Start the ascending motor and wait for the expansion

(c)

Fig 3-10 Specimen-Tensile Testing Process

4 Start the Test

(1) Enter the software application and enter some variables needed for the experiment in the

specific screen

(2) Go back to the main screen and press the [測試] (measure) button to start the test and auto

recording in the software

(3) After the specimen breaks the mechanical device will automatically stop and ask the user to

enter the total displacement We take out the specimen from the testing machine and adjust the

machinersquos position back to its original position

(4) Save the results information

(5) Record the results from the strain indicator

34 Results

From this experiment we can get the Poissonrsquos Ratio Youngrsquos Modulus and Yield Strength etc and

because of the slippage phenomenon in the clamp at the moment of the test then the Elastic Limit will

display some yield phenomena So omit any undesirable results we just take the Yield portion of the

results as reference

In the process of the experiment the most important part to attend to is the attaching of the strain

gauge because the gaugersquos purpose is to measure the strain developed during the test and this strain

might be very small If the gaugersquos angle change during the test ie is not well attached this will affect

the accuracy of the measurements of Poissonrsquos ratio and Youngrsquos modulus

55

The materials provided by the manufacturer are SUM 23 and SUM 43 steel round bars and these two

types of materials have been through different heat treatment processes so they can be sub-divided

further into untreated material heat-treated material and black surface heat treated material for the two

materials with heat treatment the treatment process and finished are different In the end we only have

the mechanical properties that were calculated after our research of these materials

All of the specifications are identical to those shown in figure 3-6

341 SUM 23

Fig 3-11 SUM 23 Untreated Material

Number 7 10

Hardness(HRB) 74 75

Yield Stress (MPa) 448 440

Tensile Strength (MPa) 544 560

Poissonrsquos Ratio 029 027

Youngrsquos Modulus (GPa) 203 210

Cut-off Area Shrinking () 42 41

Elongation () 1125 1011

Table 3-5 Mechanical Properties of SUM 23 Untreated

56

Stress-Strain Diagram

(a)

(b)

57

Fig 3-12 Stress-Strain Diagrams for (a) 7 Round Bar and (b) 10 Round Bar

Cut-Off Area

(a)

(b)

Fig 3-13 Cut-Off Area of (a) 7 Round Bar and (b) 10 Round Bar

58

SUM 23 Nickel Round Bar

Fig 3-14 SUM 23 Nickel Material

Number 1 2 3 4

Hardness(HRB) 48 50 49 48

Yield Stress (MPa) 370 370 380 400

Tensile Strength (MPa) 455 451 450 450

Poissonrsquos Ratio 028 046 029 026

Youngrsquos Modulus (GPa) 243 303 246 206

Cut-off Area Shrinking () 803 803 726 601

Elongation () 566 65 602 647

Table 3-6 Mechanical Properties of SUM 23 Nickel

59

Stress-Strain Diagram

(a)

60

(b)

(c)

(d)

61

Fig 3-15 Stress-Strain Diagrams for (a) 1 Round Bar (b) 2 Round Bar (c) 3 Round Bar and (d)

4 Round Bar

Cut-Off Area

(a)

(b)

62

(c)

(d)

Fig 3-16 Cut-Off Area of (a) 1 Round Bar (b) 2 Round Bar (c) 3 Round Bar and (d) 4 Round

Bar

63

SUM 23 Black Surface Round Bar

Fig 3-17 SUM 23 Black Surface Material

Number 1 2 3

Hardness(HRB) 51 50 51

Yield Stress (MPa) 378 371 369

Tensile Strength (MPa) 467 465 464

Poissonrsquos Ratio 03 016 04

Youngrsquos Modulus (GPa) 215 266 266

Cut-off Area Shrinking () 986 94 848

Elongation () 748 805 761

Table 3-7 Mechanical Properties of SUM 23 Black Surface Material

64

Stress-Strain Diagram

(a)

(b)

65

(c)

Fig 3-18 Stress-Strain Diagrams for (a) 1 Round Bar 2 Round Bar and (c) 3 Round Bar

Cut-Off Surface

(a)

66

(b)

(c)

Fig 3-19 Cut-Off Surface of (a) 1 Round Bar 2 Round Bar and (c) 3 Round Bar

67

342 SUM 43

Fig 3-20 Untreated SUM 43 Untreated Material

Number 1 5

Hardness(HRB) 76 75

Yield Stress (MPa) 572 594

Tensile Strength (MPa) 743 785

Poissonrsquos Ratio 027 029

Youngrsquos Modulus (GPa) 200 202

Cut-off Area Shrinking () 338 2944

Elongation () 857 894

Table 3-8 Mechanical Properties of SUM 43 Untreated

68

Stress-Strain Diagrams

(a)

(b)

Fig 3-21 Stress-Strain Diagrams for SUM 43 (a) 1 Round Bar and (b) 5 Round Bar

69

Cut-Off Area

(a)

(b)

Fig 3-22 Cut-Off Area of SUM 43 (a) 1 Round Bar and (b) 5 Round Bar

70

SUM 43 Nickel Round Bar

Fig 3-23 SUM 43 Nickel Material

Number 4 5

Hardness(HRB) 51 50

Yield Stress (MPa) 1580 1544

Tensile Strength (MPa) 1639 1625

Poissonrsquos Ratio 03 028

Youngrsquos Modulus (GPa) 194 201

Cut-off Area Shrinking () 1697 137

Elongation () 376 265

Table 3-9 Mechanical Properties of SUM 43 Nickel

71

Stress-Strain Diagrams

(a)

(b)

Fig 3-24 Stress-Strain Diagrams for (a) 4 Round Bar and (b) 5 Round Bar

72

Cut-Off Area

(a)

(b)

Fig 3-25 Cut-Off Area of (a) 4 Round Bar and (b) 5 Round Bar

73

SUM 43 Black Surface Material

Fig 3-26 SUM 43 Black Surface Material

Number 3 5

Hardness(HRB) 56 56

Yield Stress (MPa) 1416 1361

Tensile Strength (MPa) 1591 1402

Poissonrsquos Ratio 029 031

Youngrsquos Modulus (GPa) 200 202

Cut-off Area Shrinking () 139 124

Elongation () 24 24

Table 3-10 Mechanical Properties of SUM 43 Black Surface Material

74

Stress-Strain Diagrams

0 2 4 6 8 10 12 14

-200

0

200

400

600

800

1000

1200

1400

1600

1800

應力 (MPa)

應變()

(a)

0 2 4 6 8 10

-200

0

200

400

600

800

1000

1200

1400

1600

應力

(MPa)

位移 ()

(b)

Fig 3-27 Stress-Strain Diagrams for (a) 3 Round Bar and (b) 5 Round Bar

(Note These curves were formulated using Visual Solutions Inc VisSim Software)

75

Cut-Off Area

(a)

(b)

Fig 3-28 Cut-Off Area of (a) 3 Round Bar and (b) 5 Round Bar

76

The force value (N) was retrieved from the Universal Testing Machine

The Poissonrsquos Ratio (ε) is calculated as

ε =

the values for the Poissonrsquos Ratio are in average around 0297

The Youngrsquos Modulus (E) is calculated as

E =

Where

Stress =

Cross-sectional Area =

where D is the Diameter

The value for D was in average around 1258 mm

The values shown by the computer because there is Slippage phenomena between the Clamp and the

specimen will not be taken into consideration for the elongation strain and Youngrsquos modulus and we will

refer to the values that we have meticulously calculated

77

Chapter 4 AR COATING IN DEPTH

41 Experimentrsquos Purpose and Principles

By means of a vacuum chamber and several other instruments we intend to apply Anti-Reflective

Coating using deposition process to a laser diode and in this way reduce its refraction so as to make it

lose less light in the process of amplification and we can control certain wavelengths we want produced

for certain desired applications in our case we are attempting to re-create a Bose-Einstein Condensate

An optimal BEC apparatus is shown in figure 4-1

Fig 4-1 BEC Apparatus

The main point of this experiment is to build a vacuum chamber system attach all the instrumentation

needed (Vacuum pump deposition meter and voltmeter) and use it to apply AR coating to a laser diode

After we have accomplished the AR coating other team will be in charge of designing the BEC apparatus

and use the results of our research

78

42 Experimentrsquos Equipment

421 Vacuum Chamber

For this research we designed a vacuum chamber whose main body is shown in figure 4-2 Its

dimensions are

Width 240 mm

Length 240 mm

Height 200 mm

Outer Diameter 4 in

Inner Diameter 15 in

Fig 4-2 Vacuum Chamber Main Body

The chamber is made up of 6 pass ways pass way A is the connection with the Laser Deposition

Equipment pass way B is the connection with the Turbo Pump and pass way C is for the connection with

the Deposition Source

A

C

B

79

Pass way C is for the deposition source as mentioned above This is a system where a thermal

resistance is heated by passing a high current through it which heats up a filament boat (made of tungsten)

where the material to be evaporated is place We control the temperature as such that the material will

evaporate and the heat will not cause the filament boat to crack

Because P = Isup2 R (where P is power I is current and R is resistance) to avoid the current to flow

where it is not desired we decided that the material for the Thermocouple shown in figure 4-3 should be

Copper ᴓ 63 mm We choose it that way because Copper has very good heat dissipation characteristics

and the resistance value is low It can reduce the value of the current enough to make the thermocouple to

create heat

Fig 4-3 Thermocouple

To the thermocouple we attach the tungsten filament boat We need to take notice of materials to be

used in this design because when using high current the tungsten filament boar will heat up and so the

material must be able to keep up with the heating potential of tungsten and has a low coefficient of heat

dissipation to avoid the tungsten to fail when heating up and therefore not evaporating Considering all

this we decide to use Stainless Steel

Because this clamp will be assembled inside the chamber after many revisions it was determined it

will have the shape shown in figure 4-4

Fig 4-4 Filament Boat Clamp Design

80

For the tungsten filament boat we bought the product from a distributor The dimensions are

Length 100 mm

Width 10 mm

Height 1 mm

Our thermocouple is 15 in but the pass way C is 4 in so we need to attach a Flange that connects

15in to 4in Because these specifications are quite difficult to achieve by Milling we had to use

electrical wire cutting

For the laser clamping system where the laser that is going to be AR coated will be placed will be

connected to pass way A the assembly is shown in figure 4-5 below

Fig 4-5 Cover Assembly

For this design we used an O-ring instead of a gasket so as to save time The design of the assembly

where the laser will be placed is shown in figure 4-6

Fig 4-6 Upper Cover Inner Assembly

D

E

F

81

Point D is the plate in the assembly where the laser diode will be fixed Because of the easy

processing we decide to use Aluminum and it is screwed to the top cover Point E is the connection for

the Quartz crystal resonator and it is designed in the same as point F in this way the results of the quartz

microbalance system will be more accurate in real time Point F is the final resting place for the laser

diode We use a Thor Labs Base with dimensions of ᴓ 9mm and ᴓ 56mm for two different size laser

diodes It just needs to be plugged in for easy installation

From figure 4-6 we know that the system needs signal system connections and because of the

change in temperature inside the chamber this could affect the functioning of the quartz microbalance so

we also need to install water tubes for cooling This is shown in figure 4-7 below

Fig 4-7 Diagram of Upper Cover Connections

In figure 4-8 we show the Feed through connections and their functions

Fig 4-8 Feed through Diagram

82

1 SQM-160 wire 5 Laser Connection 1 (Vin)

2 SQM-160 (G) 6 Laser Connection 2 (G)

3 K-Type-1 7 Laser Connection 3 (PD)

4 K-Type-2 8 Not In Use

The fully assembled chamber is shown in figure 4-9

Fig 4-9 Fully Assembled Chamber

422 Quartz Crystal Microbalance

For measuring the deposition on our target for coating we used the Inficon SQM-160 RateThickness

Monitor It is an easy to use instrument for measuring many types of thin-film coatings as shown in

figure 4-10

(a) Front Panel (b) Back Panel

Fig 4-10 Inficon SQM-160

83

Table 4-1 shows the technical specifications for this equipment

Number of sensors 2 Standard 4 additional optional

Sensor Frequency Range 40 MHz ~ 60 MHz

Reference Frequency Accuracy 002

Thickness Display Resolution 1 Aring

Thickness Resolution 015 Aring (Std) 0037 Aring (Hi Res)

Density of Stored Films 05-9999 gmcc

Tooling 10-399

Z-Factor 010-1000

Final Thickness 0000-9999k Aring

Measurement Period 15 to 2 sec

Simulation Mode Yes

Frequency Mode Yes

Rate Resolution 011 Arings

Dual Crystal Yes

Etch Mode Yes

Crystal Tooling 10-399

Crystal Fail Min Max 40 to 60 MHz 41 to 61 MHz

Power 100-120 200-240~plusmn10 nominal 20W

Operation Environment 0degC ~ 50degC

0 ~ 80 RH non-condensing

0 ~ 2000 meters

Class 1 Equipment

Pollution Degree 2

Rack Dimensions 885mm x 2127mm x 1969mm

Weight 27 kg

Table 4-1 Inficon SQM-160 RateThickness Monitor Specs

84

To the SQM-160 we need to connect an Oscillator We use the Sigma Instruments Remote Oscillator

Ser No 2 268 as shown in figure 4-11

Fig 4-11 Sigma Instruments Remote Oscillator

The connections diagram is shown in figure 4-12

Fig 4-12 SQM-160 Connections Diagram

85

423 Turbo Pump

For our experiments we used the Pfeiffer TCP 015 Electronic Drive Unit shown below in figure 4-13

Table 4-2 shows the technical specifications for this equipment

(a) Front Panel (b) Back Panel

Fig 4-13 Pfeiffer TCP 015 Electronic Drive

Connection Voltage (100V) 90-112

Mains Frequency 5060 Hz

Start-up Current 22 A

Nominal Frequency 1500 Hz

Rotation Speed 10V = 1500Hz plusmn2

Analog Output Current 10 V = 25 A plusmn 5

Rotation Speed Switchpoint 750 Hz

Works Setting 8 min

Permissible Ambient Temperature 0degC ~ 40degC

Dimensions Front Panel 1285mm x 1063mm

Insertion Length 227mm

Weight 27 Kg

Table 4-2 Pfeiffer TCP 015 Electronic Drive Specs

86

The connections diagram is shown in figure 4-14

Fig 4-14Connections Diagram for Pfeiffer TCP 015

To measure the pressure inside the chamber we use the Granville Phillips 375 Convectron Vacuum

Pressure Controller shown in figure 4-15

(a) Front Panel (b) Back Panel

Fig 4-15 Granville Phillips 375 Convectron

87

Its dimensions are shown in figure 4-16

Fig 4-16 Dimensions of Convectron

Table 4-3 shows the technical specifications for this equipment

Table 4-3 Granville Phillips 375 Convectron Vacuum Pressure Controller Specs

88

424 Multimeter

For our experiment we used the Keithley 2000 Digital Multimeter as shown in figure 4-17

(a) Front Panel (b) Back Panel

Fig 4-17 Keithley Model 2000 6-12-Digit Digital Multimeter

Its technical specifications are shown in table 4-4

Table 4-4 Keithley Model 2000 6-12-Digit Digital Multimeter Specs

89

43 Experiment Procedure

1 Connecting together the equipment and the chamber

(1) We first connect the resonator to the thickness monitor and connect the other side to the

chamber

(2) We now connect the flexible tubes to the turbo pump on one side and to the chamber on the

other

(3) We need to check that tubes are tightly connected to avoid any leaks in the vacuum pumping

process which will not allow us to get to our goal of Torr As shown in figure 4-18

(4) Connect the convectron to the system as shown in figure 4-19

Fig 4-18 checking for leaks using alcohol

Fig 4-19 Convectron attached to System

90

(5) Attach the clamps of the Multimeter to the bottom of the chamber as shown in figure 4-20

(6) Place the Quartz crystal in place

(7) Close tight vacuum chamber

(8) Connect all electrical appliances to power source

Fig 4-20 Multimeter Connections

2 Starting up the System

(1) We turn on all the devices as such Check all systems are ready to function Reset all values

that might be left over from previous tests

(2) Start the thickness monitor and set all values for this experiment In our case we got to testing

the system but not actual coating So we used the simulation mode of the thickness monitor as

shown in figure 4-21

Fig 4-21 Simulation Mode

91

(3) Start the turbo pump Make sure the lid on the vacuum chamber is tightly closed

(4) Start convectron and record initial pressure

(5) Start Multimeter and record initial current

3 Coating Process

(1) If we have the deposition material inside the filament boat the power source for the high

current must be started as well

(2) Record all initial values for thickness current pressure

(3) For an ideal experiment we need a thickness of around 101 nm a pressure of Torr and

a current of 300 A

44 Results

From previous experiments we have shown that we can turn a LED into a laser by means of AR

Coating In figure 4-22 shown below we can compare the actual results of a Diode before and after AR

coating From the blue line we can see that when the diode is at a current of 15mA its light will change

from LED to laser and if we look at the red line its critical current is around 30 to 35 mA

Fig 4-22 AR Coating Comparison for Laser Diodes

This means that the light emitted is not as strong as if the diode had been coated because inside the

chamber there must be some excitation first so the reflectivity of both sides inside the diode must be high

So because of the coating in one of the sides we have opened a door and let the light come out so the

critical current is risen as such and will be higher value than that of before the coating

92

In the following figures we can see the difference between before and after coating in a material The

thickness is around 1016 nm for this material

Fig 4-23 Before Coating

Fig 4-24 After Coating

93

Chapter 5 CONCLUSIONS AND RECOMMENDATIONS

51 Conclusions

For the first part of this independent study taking into consideration the data that came out of our

research and that sent by the provider we can say

1 SUM 23 after heat treatment will unexpectedly develop cracking in the middle of the tensile

testing process and suddenly break

2 Itrsquos possible that in the process of heat treatment to the SUM 23 material the treatment was not

uniform and this will create a pre-loaded moment force on one side that pushes on the other side

of the specimen resulting in material deformation

3 In the process of attaching the strain gauges to the materials it is very easy to make errors due to

poor adhesion or sudden removal in the tensile testing process

For our second part of the independent study the following can be made

1 At the beginning of this independent study we had no idea what Bose-Einstein Condensate was

or what was its purpose After much literature we finally comprehended the basic principles to

put into practice for our research

2 Our systemrsquos basic working principles and equipmentrsquos complexity are a little difficult to grasp

but hopefully we were able to understand enough of it

3 Theoretically from relation between the power and current we can know the advantages and

disadvantages of AR Coating

4 We were able to assemble the system and run test on its functions Even though we were able to

do this there is still much more work left to do with this system

52 Recommendations

For the Tensile Testing the following can be said

1 Ask the provider to check on the process of heat treatment on the SUM 23 material and give

them the information we have gathered through our test so they can correct for the mechanical

properties found if any change is needed

2 To avoid the problem of the inaccuracy of the poor adhesion of strain gauges we can attach

multiple strain gauges to the same one specimen so as to correlate data and improve our results

For the AR Coating the following can be said

1 We need to make sure that there are no physical defects on the main body of the chamber so as to

achieve maximum efficiency in the vacuum process If there was then the vacuum will arrive to

certain point and then start to decrease

2 It would be preferable to add some sort of visual aid that will allow the user to check the inside of

the chamber without actually opening it This will help us determine at what times we should

manipulate the current to better evaporate the substrate

94

REFERENCES

[1] A L Window Strain Gauge Technology Elsevier Applied Science London and New York 2nd

Edition 1992

[2] CC Perry and HR Lissner Strain Gauge Primer McGraw-Hill Book Co Inc New York 1955

[3] James W Dally William F Riley McGraw-Hill 1978

[4] University of Colorado Boulder BEC - What is it and where did the idea come from

httpwwwcoloradoeduphysics2000becwhat_is_ithtml

[5] Ultraslow Light amp Bose-Einstein Condensates Two-way Control with Coherent Light amp Atom

Fields Harvard Hau Lab Dr Lene Vestergaard Hau Optics amp Photonics News 16 1995

[6] The Art of Taming Light Ultra-slow and Stopped Light Harvard Hau Lab Dr Lene

Vestergaard Hau Europhysics News 2004

[7] Nonlinear Optics Shocking Superfluids Harvard Hau Lab Dr Lene Vestergaard Hau Nature

Physics 2007

[8] Model P3 Strain Indicator and Recorder Instruction Manual Vishay Micro-Measurements 2005

[9] Granville-Phillips Series 375 Convectron Vacuum Gauge Controller Instruction Manual Brooks

Automation 2008

[10] Effect of Film Thickness on the Validity of the Sauerbrey Equation for Hydrated Polyelectrolyte

Films Vogt Lin Wu White 2004

[11] Quartz Crystal Microbalance Study of DNA Immobilization and Hybridization for DNA Sensor

Development Chang Zhao 2008

[12] Installation of Strain Gages with SR-4 PrecoatAdhesive Vishay Micro-Measurements 2005

[13] Strain Gauge Measurement ndash A Tutorial National Instruments 1998

[14] Correlation between Vickers Hardness Number and Yield Stress of Cold-Formed Products

Yavuz Tekkaya

[15] httpsenwikipediaorg

Page 15: PC Hinge Materials Testing and AR Laser Diode Coating

15

Elastic Deformation When the external load goes over the Elastic limit only then does the specimen

presents Plastic Deformation This type of deformation which is irreversible even when the load is

removed comes after the material does under elastic deformation so this means the object will first come

part way to its original shape Common metals and ceramics have roughly the same elastic limits

212 Yield Strength and Yield Point

Some materials display very evident yield phenomena while some materials donrsquot as shown in Fig

2-2 After we exceed the elastic limit if we continue to exert load when we arrive to a certain value

which differs under different materials and external conditions there is sudden decrease in stress and this

is called the Yield Strength and can be defined as the stress at which a material begins to deform

plastically using the equation

σyield =

Where P is the tension force and Ao is the original cut-off area

The stress remain at a certain value after the decrease but the strain increases this phenomena can be

easily appreciated when studying the behavior of common Carbon Steel Fig2-2 (a) but most metals (like

Aluminum Copper or High Steel Carbon) donrsquot display this kind of behavior as shown in Fig 2-2 (b)

Arriving to this point is very difficult and the most commonly used method for this is to add a 02 or

0002 offset yield strength to the curve This point is held constant on the strain axis of the curve and

from the 0002 position we draw a straight line parallel to the linear relationship line the point at where

this line and the stress-strain curve intercept is the point we take as the 02 offset yield strength

(a)Evident (b) Non-evident

Fig2-2 Stress-Strain Curve Comparison on Metals

16

213 Ultimate Tensile Strength and Breaking Strength

After materials undergo yield they keep lending strength and hardening phenomena occurs (work

hardening) on the material and the external load increases When it has reached the highest point this is

called the Ultimate Tensile Strength (UTS) as shown in Fig2-1 The UTS is defined as

σUTS =

Where Pmax is the load at the materialrsquos ultimate tensile strength point and Ao is the original cut-off

area For brittle materials the ultimate tensile strength is the most important mechanical property for

ductile materials the ultimate tensile strength is not commonly used for industrial and designing purposes

because upon arriving to this value the material already has forgone great plastic deformation After the

specimen goes through UTS there will be necking phenomena which is a mode of tensile deformation

where relatively large amounts of strain localize disproportionately in a small region of the material It

results from instability during tensile deformation when a materialrsquos cross-sectional area decreases by a

greater proportion than the material strain hardens The specimen continues to elongate until it finally

breaks and the load at this point is called Breaking Strength The breaking strength is defined as the

greatest stress in tension that a material is capable of withstanding without rupture

Where Pf is the load at the materialrsquos breaking strength point and Ao is the original cut-off area

214 Poissonrsquos Ratio (ν)

For elastic deformation when materials are compressed in one direction they tend to expand in the

other two directions perpendicular to the direction of compression This is called the Poissonrsquos Effect

The Poison Ratio is a measure of the Poissonrsquos effect It is the ratio of the fraction of expansion divided

by the fraction of compression for small values of these changes

ν=-

215 Strain Gauge Basic Principles

The strain gauge is a device used to measure the strain of an object Itrsquos an elongated metal resistor

which is attached to the specimen being measured and when the specimen is under strain and starts to

deform the strain gauge will have a change in the resistance With the change in value we can calculate

the elementrsquos strain or elastic modulus and the Poissonrsquos ratio

It takes advantage of the physical property of electrical conductance and its dependence on the

conductorrsquos geometry When the electrical conductor (the specimen being tested) is stretched within the

limits of elasticity such that it does not break or deform plastically it will become narrower and longer

17

which increases the electrical resistance through-out From the measured resistance of the strain gauge

the amount of stress may be inferred by using the relations

R=

Where R is the original resistance value is the electrical resistivity lo is the original length of the

conductor and Ao is the original cross sectional area of the conductor If after the application of tension

the change in length is Δl let the length of the specimen be l = l + Δlo and the tension is the same

through-out So

And the resistance is

The Gauge Factor is the ratio of relative change in electrical resistance to the mechanical strain in

other words it is the relative change in length It is defined as

The strain gauge was invented in 1938 by Edward E Simmons and Arthur C Ruge and the most

common type consists of an insulating flexible backing which supports a metallic foil usually made of a

brass-nickel alloy It is attached to the specimen by a suitable adhesive As the object is deformed the foil

also deforms and this causes the electrical resistance to change Then this is usually measured using a

Wheatstone bridge shown below and is related to the strain by the Gauge Factor

Fig2-3 Basic Structure of Strain Gauge

18

Fig 2-4 Strain gauge attached to Wheatstone bridge

22 Hardness Testing Basic Principles

221 Brinell Scale BHN

The Brinell Scale characterizes the indentation hardness of materials through the scale of penetration

of an indenter loaded on a material specimen The typical test uses a 10mm diameter steel ball as indenter

(usually of value equal to BHN450) with a 29kN force For softer materials smaller force is used The

indentation is measured and BHN is calculated using the relation

BHN =

radic

Where F is the applied force usually within the range of 100 250 500 750 1000 1500 2000 2500

and 3000 kgf D is the diameter of indenter usually within the range of 5mm or 10mm plusmn0005 margin

and d is the diameter of indentation usually around 2mm Its units are of Kgmmsup2 but are not normally

written

First proposed by Swedish engineer Johan August Brinell in 1900 it was the first widely used and

standardized hardness test in engineering and metallurgy although the large size of indentation and

possible damage to specimen limits its usefulness

Fig 2-5 Brinell Indentation Fig2-6 Brinell Hardness Tester

19

222 Rockwell Scale HR

The Rockwell scale is a hardness scale based on the indentation hardness of a material The Rockwell

test determines the hardness by measuring the depth of penetration of an indenter under a large load

compared to the penetration made by a preload The indenter is forced into the specimen under a

preliminary load When equilibrium is reached a measuring device follows the movements of the

indenter and responds to changes in depth of penetration of the indenter While the preload is still being

applied additional major load is applied resulting in increased penetration When equilibrium is reached

again the major load is removed but the preload is maintained Removing the major load allows partial

recovery and reduces the depth of penetration The permanent increase in depth of penetration resulting

from the application and removal of the major load is used to calculate the Rockwell number using the

relation

HR = E ndash e

Where E is a constant depending on the form of the indenter 100 units for diamond indenter and 130

units for steel ball indenter e is the permanent increase in depth of penetration due to the major load

measured in units of 0002mm

Fig 2-7 Rockwell Indentation

When testing materials indentation hardness is related linearly to the tensile strength The important

relation permits economically important nondestructive testing of bulk metal deliveries with lightweight

equipment like the Rockwell tester shown below in figure 2-7

Fig 2-8 Rockwell Hardness Tester

20

There are different scales denoted by a single letter that use different loads or different indenters

The result is a dimensionless number denoted as HR X where X will be the letter denoting the scale as

shown below in table 2-1

Table 2-1 Rockwell Hardness Test Scale

Differential depth hardness measurement was first conceived in 1908 by Viennese professor Paul

Ludwik It eliminated the errors associated with the mechanical imperfections of the system such as

backlash and surface imperfections in the specimen Rockwell testing has an advantage over Brinell

testing because the latter was slow itrsquos not useful on fully hardened steel and left too large an impression

to be considered nondestructive

The tester was co-invented by Hugh M Rockwell and Stanley P Rockwell The requirement for this

tester was to quickly determine the effects of heat treatment on steel bearing races

21

223 Vickers Hardness Test HV

This is a type of microindentation hardness test where a diamond indenter of specific geometry is

impressed into the surface of the test specimen using a known applied force ranging from 10 to 1000

grams This type of tests usually has forces of 2N and produce indentations of about 50μm They can be

used to observe changes in hardness on the microscopic scale It is difficult to standardize the

microhardness measurements because it has been found that the microhardness of almost any material is

higher than its macrohardness The values also vary with load and work-hardening effects of materials

The Vickers test is often easier to use than other hardness tests because the required calculations are

independent of the size of the indenter and the indenter can be used for all materials It can be used for all

metals and has one of the widest scales among hardness tests The unit of the Vickers test is denoted as

HV and can be converted to units of Pascal (Pa) but it is not a measurement of pressure The hardness

number is determined by the load over the surface area of the indentation and not the area normal to the

force

A square-based pyramid shaped diamond is use as the indenter It has been established that the ideal

size of a Brinell impression was 38 of the ball diameter As two tangents to the circle at the ends of a

chord 3d8 long intersect at 136plusmn05deg it was decided to use this as the angle of the indenter giving an

angle to the horizontal plane of 22deg on each side The HV number is determined by the ratio FA where F

is the force applied to the diamond in kgf and A is the surface area of the resulting indentation in mmsup2 A

can be determined by the relation

A =

Where A is the surface area of indentation and d is the average length diagonal left by the indenter

This can be approximated as

A =

Then the Vickers Number is

HV =

=

Vickers hardness number is reported as xxxHVyy or xxxHVyyzz (if duration of applied force differs

from 10s to 15s) where xxx are replaced by the hardness number yy is the load in kg and zz indicates

loading time The values are generally independent of test force

The test was developed in 1921 by Robert L Smith and George E Sandland at Vickers Ltd as an

alternative to Brinell method to measure the hardness of materials

22

Fig 2-9 Vickers Indentation Fig 2-10 Vickers Hardness Tester

23 AR Coating

231 Bose-Einstein Condensate

The Bose-Einstein Condensate or BEC is a state of matter of a dilute gas of bosons cooled to

temperatures very near absolute zero around 0K or -27315degC Under such conditions a large fraction of

the bosons occupy the lowest quantum state where the quantum effects become apparent on a

macroscopic scale This gave birth to the Bose-Einstein Statistics which are the rules that govern the

behavior at this state It is one of the two possible ways in which a collection of indistinguishable particles

may occupy a set of available discrete energy states The aggregation of particles in the same state

accounts for the cohesive streaming of laser light and the frictionless creeping of superfluid helium (an

application discussed later) Bose and Einstein recognized that a collection of identical and

indistinguishable particles can be distributed this way This theory applies only to those particles not

limited to single occupancy of the same state particles that do not obey the Pauli Exclusion Principle

restrictions Such particles are the Bosons named after the statistics that correctly describe their behavior

This phenomenon was first predicted by Satyendra Nath Bose around 1924 when he considered how

groups of photons behave He then asked Albert Einstein for help publishing his discoveries to which

Einstein agreed and gave follow up supporting these findings The resulting efforts became the concept of

a Bose gas governed by the Bose-Einstein Statistics described above Einstein demonstrated that cooling

bosonic atoms to a very low temperature would cause them to condense into the lowest accessible

quantum state resulting in a new form of matter

The first gaseous condensate we produced by Eric Cornell and Carl Wieman at the University of

Colorado at Boulder NIST ndash JILA lab sung a gas of rubidium atoms cooled to 170 nK which earned

them the 2001 Nobel Prize in physics together with Wolfgang Ketterle from MIT The transition to BEC

occurs below a critical temperature which for a uniform three dimensional gas consisting of

non-interacting particles with no apparent internal degrees of freedom is given by

23

Tc =

(

)

asymp 33125

Where Tc is the critical temperature n is the particle density m is the mass per boson h is the

reduced Planck constant k is the Boltzmann constant and ζ is the Riemann zeta function

There are two classes of elementary particles defined by whether their quantum spin is a nonnegative

integer or an odd half integer A Bose-Einstein Condensate is shown below in figure 2-11

Fig 2-11 Bose Einstein Condensate at different scales

Bosons are the particles whose quantum spin is a nonnegative integer (s = 0 1 2 etc) Examples of

bosons include fundamental particles (Higgs Boson Photons W and Z Bosons Gluons Gravitons etc)

composite particles (Mesons Hadrons Nuclei and Atoms of Carbon-12 and Helium-4) and

quasi-particles Bosons are considered force carrier particles The Bosons differ from Fermions in that

there is no limit to the number that can occupy the same quantum state This is called the Pauli Exclusion

Principle

The Pauli Exclusion Principle says that no two identical fermions may occupy the same quantum state

simultaneously in other words this means that the total wave function for two identical fermions is

anti-symmetric with respect to exchange of the particles This means that no two electrons in a single

atom can have the same four quantum numbers

Fermion is any particle characterized by Fermi-Dirac Statistics and follows the Pauli Exclusion

Principle described above Quarks Leptons and composite particles (Hadrons Nuclei and Atoms of

Carbon-13 and Helium-3) made of an odd number of these are considered Fermions It can be an

elementary particle such as the electron or a composite particle such as the protons Following the Pauli

24

Exclusion Principle only one fermion can occupy a particular quantum state at any given time If multiple

fermions have the same spatial probability distribution then at least one property of each fermion must be

different Fermions are usually associated with matter because composite fermions are key building

blocks of matter (neutrons and protons)

Fermionsrsquo behavior by the Fermi-Dirac Statistics which describes the energies of single particles in a

system comprising of many identical particles It applies to identical particles with half-odd integer spin

in a system of thermal equilibrium The particles in the system are assumed to have negligible mutual

interaction This allows the many-particle system to be described in terms of single-particle energy states

The result is the Fermi-Dirac distribution of particles over these states and includes the condition that no

two particles can occupy the same state which has considerable effect on the properties of the system

In quantum mechanics the position of an object is uncertain An object has a definite probability of

being at any given point in space This probability is encoded in the wave function mentioned earlier If

one concentrates a large number of identical bosons in a small region then it is possible for their wave

functions to overlap so much that the bosons lose their identity When this happens thatrsquos a Bose-Einstein

Condensate It is only possible at very low temperatures because at high temperatures the individual

bosons have small wave functions and move rapidly which causes them to fly apart

For now applications are still restricted because there are still some setbacks regarding BECs They

are extremely fragile they are being produced in small quantities with just a few million atoms at a time

and finally they can only be made from certain types of atoms Some examples are the atom laser Ketterle

in which a conventional light lase emits a beam of coherent photons this means they are all in phase and

can be concentrated to an extremely small bright spot BECs can slow down light as demonstrated by

Prof Lene Hau PhD in 2001 by the use of a superfluid [7] These manipulations could develop into

new types of telecommunications technology optical storage and quantum computing

BECs are related to super-fluidity and super-conductivity Super-fluidity is the state of matter in

which the behavior is that of a fluid with zero viscosity It was discovered in liquid helium but now it has

applications in astrophysics high-energy physics and theories of quantum gravity

Super-conductivity is a phenomenon of exactly zero electrical resistance and expulsion of magnetic

fields occurring in certain materials when cooled below a characteristic critical temperature A

super-conductor is shown below in figure 2-12

Fig2-12 Super Conductor

25

232 AR Coating Basic Principles

Anti-reflective (AR) coating is a type of optical coating applied to the surface of lenses and other

optical devices (in our case we planned to apply it to a laser diode) to reduce reflection This improves

the efficiency of the system since less light is lost The primary benefit is the elimination of the reflection

itself

When light the medium (glass) it will produce reflection if 100 of the light comes from the air and

enters the glass because therersquos a difference between the index of refraction some of the light will go out

and when the light is coming out of the glass into the air once again because of the difference between

index of refraction some of the light wonrsquot be able to pass through the medium

When the light makes the first trip into the glass there was a loss of about 4 in the reflection and

when the light makes the trip back outside there was another loss of about 4 so when we assume that

100 of the light interacts with the medium actually therersquos just about 92 acting (we neglect the light

absorbed by the glass around 05) To illustrate this idea please refer to figure 2-13

Fig 2-13 Simple Model for Light in Glass Medium

When we apply the AR Coating the light that enters will only have a loss of about 05 and when

making the trip back outside again only 05 of light is loss so we get the result of increasing the light

passing through up to 99 (again neglecting the light absorbed by the glass around 05) To illustrate

this idea please refer to figure 2-14

26

Fig 2-14 Simple Model for Light in Glass Medium after AR Coating

The AR Coating can reduce reflection of incoming light In the case that light hits perpendicular to

the surface of the medium the intensity of the reflection can be calculated using the Reflection

Coefficient

Where n0 and ns are the refractive indices of the first and second media respectively The value of R

varies from 0 (no reflection) to 1 (all light reflected) and is usually quoted as a percentage

Complementary to R is the transmission coefficient or Transmittance If absorption and scattering are

neglected then the value of Transmittance is always 1-R then if a beam of light with intensity I is

incident on the surface a beam of intensity RI is reflected and a beam with intensity TI is transmitted to

the medium

The optimal value is called the Optimal Index of Refraction and is described as

For glass with ns around 15 in air (n0 around 10) then the optimum refractive index will be n1 =

1225

To reduce the refraction in this case we now mean the one that is produced inside the chamber of the

Laser diode the easiest way is to apply a low reflectivity AR coating on the surface of the laser To

measure the appropriate thickness of the coating layer we can use the equations described above By

applying a coat exactly

thickness film we can assure that a certain wavelength is transmitted The

27

reflected waves from the back of the glass medium will be half a wavelength out of phase So they

interfere destructively Because all reflected waves are interfered the maximum amount of light passes

through the coating Please refer to figure 2-15 to illustrate this idea

Fig 2-15 Light Passing through AR Coat and Glass

The most common process to attain this final product is by vacuum deposition For the best coating

results we need to lower the pressure inside the vacuum system to torr

Fig 2-16 Lens without (Top) and With (Bottom) AR Coating

28

233 Laser Diode Basic Principles

A laser diode is a laser whose active medium is a semiconductor similar to that found in

light-emitting diodes (LEDs) Please refer to figure 2-17 The most common type of laser diode is formed

from a p-n junction and powered by injected electric current

Fig 2-17 Laser Diode

Laser diodes are formed by doping a very thin layer on the surface of a crystal wafer The crystal is

doped to produce the n-type region and a p-type region one above the other

By referring to figure 1-2 we can see the basic structure of a working laser When the laser diode has

a current passing through it the light will get excited inside its gain medium and then will start to

resonate this process is called pumping The current exceeds the critical current and then it comes out as

laser light Please refer to figure 1-3 Since we use an external cavity laser we need to apply the AR

coating to the diode and adjust a diffraction grating The laser light comes out the diode and bounces on

the grating making the resonance externally and this becomes the ldquocavityrdquo as shown in figure 2-18

Fig 2-18 Tunable Laser Basic Configuration

29

The most important feature of the external cavity laser is that we can adjust the wavelength easily just

by changing the diffraction gratingrsquos angle and in the end this is the output wavelength of the laser For

different wavelengths there will be different levels of visible light as shown in figure 2-19

Fig 2-19 Light Spectrum

234 Quartz Microbalance System

A Quartz Crystal Microbalance is an instrument that measures a mass per unit area by measuring the

change in frequency of a quartz crystal resonator The resonance is disturbed by the addition or removal

of a small mass due to oxide growthdecay or film deposition (which is the case in our study) at the

surface of the acoustic resonator The QCM can be used under vacuum in gas phase and more recently in

liquid environments It is useful for monitoring the rate of deposition in thin film deposition systems

under vacuum Frequency measurements are easily made with high precision

For our research we used the Sigma Instruments SQM-160 RateThickness Monitor shown in figure

2-20

Fig 2-20 Front and Back Panels of SQM-160

30

The microbalance uses Quartz as the resonator Quartz is one member of the family of crystals that

experience the Piezoelectric Effect

Piezoelectricity is the charge that accumulates in certain solid materials in response to applied

mechanical stress It means electricity resulting from pressure It was discovered in 1880 by Jacques and

Pierre Curie It is understood as the linear electromechanical interaction between the mechanical and the

electrical state in crystalline materials with no inversion symmetry It is a reversible process in that

materials exhibiting direct piezoelectricity also exhibit the reverse This means that the internal generation

of electrical resulting from applied mechanical force and vice versa

By using the piezoelectric effect we can probe as an acoustic resonance by electrical means Applying

alternating current to the quartz crystal induces oscillations This creates a shear wave We can use these

qualities to determine the resonance frequency at high accuracy

The frequency of oscillation of the crystal is partially dependent in the thickness of the crystal During

normal operation all the variables are held constant so a change in thickness correlates directly to a

change in frequency As mass is deposited or etched away the thickness increases or decreases and so the

frequency of oscillation changes accordingly With some simplifying assumptions the frequency change

can be quantified and correlated precisely to the mass change using the Sauerbreyrsquos Equation

Developed by G Sauerbrey in 1959 it is a method for correlating changes in the oscillation

frequency of a piezoelectric crystal with the mass deposited on it It is defined as below

Where f0 is the Resonant frequency Δf is the Frequency change Δm is the mass change A is the

piezoelectrically active area of the crystal q is the Density of quartz (2648 gcmsup3) and μq is the Shear

modulus of quarts(2947x gcmssup2)

Because the film is treated as an extension of thickness Sauerbreyrsquos equation only applies to systems

in which the following 3 conditions are met

Deposited mass must be rigid

Deposited mass must be distributed evenly

The frequency change

lt002

If the change is greater than 2 the Z-match method must be used to determine the change in mass

It is defined as

Where fL is the frequency of the loaded crystal fU is the resonant frequency Nq is the frequency

constant (1668x HzAring) Δm is the mass change A is the piezoelectrically active area of the crystal

31

q is the density of quartz Z is the method constant f is the density of film μq Is the shear modulus of

quarts and μf is the shear modulus of film

The Sauerbrey equation cannot be applied to systems under liquid medium

The crystals are seed crystals plated with gold on both top and bottom for applications A crystal is

shown in figure 2-21 The QCM consists of a thin piezoelectric plate with electrodes evaporated on both

sides Due to the piezoelectric effect AC voltage across the electrodes induces a shear deformation and

vice versa The electromechanical coupling provides a simple way to detect an acoustic resonance by

electrical means

The Z also called Z-factor is a constant value for different materials and it is shown together with the

density of different materials in table 2-2 below

Fig 2-21 QCM Crystals

The Oscillator of the SQM-160 is shown in figure 2-22 and the equivalent circuit for the Resonant

Oscillator is shown in figure 2-23

Fig 2-22 SQM-160 Oscillator

32

Fig 2-23 Oscillator Circuit

33

Table 2-2 Z-Ratios for Different Materials

Table 2-2 Continued

34

Table 2-2 Continued

35

Table 2-2 Continued

36

Table 2-2 Continued

37

Table 2-2 Continued

38

Table 2-2 Continued

235 Vacuum Chamber System

Vacuum Evaporation is the process of depositing thin films of materials onto surfaces The technique

consists of pumping a vacuum chamber to pressures of less than torr and heating a material to

produce a flux of vapor in order to deposit the material onto a surface The material to be vaporized is

typically heated until its vapor pressure is high enough to produce a flux several Angstrom per second by

using an electrically resistive heater or bombardment by a high voltage beam The process was invented

by Henri Nestle in 1886 for food industry

In here the system has been pumped to a vacuum of Torr When a high current is passed

through the filament boat the filament boat is heated over the desired metal evaporation temperature and

so evaporation starts When the evaporation process is finished and the metal cools down crystals

condensate in the surface of the wafer From the weight of the evaporated material the distance between

the filament boat and the wafer we are able to calculate the deposition thickness and we can also use the

mass detector follower like the Quartz crystal resonator microbalance system In the process of

evaporation we usually use a board in between the filament boat and the wafer This is because before we

arrive to the desired evaporation temperature there will be some impurities that will be vaporized in the

controlled environment so we first use a small current and the board in between to get rid of those

impurities and this raises the purity of the deposition material

39

A vacuum evaporation system is shown in figure 2-24

Fig 2-24 Vacuum Evaporation System

Rough Vacuum 760 ~ 1 torr

Medium Vacuum 1 ~ torr

High Vacuum ~ torr

Ultra-High Vacuum Lower than torr

Table 2-3 Classification of Vacuum

For our study we need to use a Turbo Pump A regular turbo pump is shown in figure 2-25

Fig 2-25 Turbo Pump

For our research we used the Pfeiffer TCP 015 Electronic Drive Unit and Granville Phillips 375

Convectron shown below in figure 2-26

40

Fig 2-26 Control and Measurement Equipment

The electronic drive controls the turbo pump and the Convectron measures the pressure inside our

chamber The turbo pump is a type of vacuum pump used to maintain high vacuum Most turbo pumps

are centrifugal When we start the pumping we need to use a mechanical pump so as to decrease the

pressure inside the system from constant atmospheric pressure to torr and then the use dispersion

pump to continue the vacuum until we get to the desired pressure We need to notice though when we

start the dispersion pump we canrsquot turn off the mechanical pump and they both need to run together If

we need to turn off the pumping we first turn off the dispersion pump wait for it to completely stop and

then turn off the mechanical pump

Our completely assembled system is shown in figure 2-27 below

Fig 2-27 Complete System

41

Chapter 3 TENSILE TESTING IN DEPTH

31 Experimentrsquos Purpose and Principles

By means of Universal testing machine and Strain gauges we were able to observe discuss and

analyze the phenomena created when a specimen of certain material is manipulated under an external load

and determine the stress strain and deformation values later we can use the graphing methods of

stress-strain diagram to describe it

The main point of this experiment is that after the tensile specimen is tested use computer analysis

and the actual strain data and after statistical adjustment make the final results report (Tensile testing

experiment is in accordance with ASTM E8)

32 Experimentrsquos Equipment

321 Universal Testing Machine

For the materials testing experiment part of this research we use a Universal Testing Machine as

shown in figure 31 The maximum load it can apply is 100 Ton After the test specimen is secured on the

device with the use of instrumentation the load exerted and the effects of this become apparent on the

specimen and even the smallest of changes can be recorded For our research we used the Chun Yen

Testing Machines Co Ltd 100 Ton Micro Computer Universal Tensile Tester

Fig 31 Universal Testing Machine

42

Table 31 shows the specifications for this machine

Max Capacity 100 Ton

Accuracy plusmn1

Tension (mm) Max Space 1150mm

Grip for Rod 20-70mm

Ram Stroke 250mm

Effective Column Interval 940mm

Crosshead Speed 300mmmin

Testing Speed 0-50mmmin

Volume of Machine 1700times1000times3350mm(LtimesWtimesH)

Volume of Control Panel 1000times800times1500mm(LtimesWtimesH)

Weight 8000kg

Power 3∮220V 20A

Computer AMD K6-2-350

OS Windows XP

Screen 15rdquo CRT

Table 3-1 Chun Yen Testing Machine Specs Table

The connections diagram is shown in figure 3-2

Fig 3-2 Diagram for System Connections

43

When the test specimen is placed when the external force is applied the Load Cell can measure the

size of the applied force and the Encoder measures the expansion rate of change The Local Controller

receives all the information from the 2 units after arranging the results they are displayed in the

computer and they can be afterwards submitted for more complex analysis such as Finite Element

Analysis and we can get the Stress-Strain Diagram

322 Strain Measurement Equipment

The equipment used in our research provides a four-channel measurement that means we can use up

to 4 strain gauges at a time to do our measurements and provides 3 different bridge arrangements as

shown in figure 3-3

(a) (b) (c)

Fig 3-3 Input Connections for Strain Indicator

Figure 3-3 (a) is the Quarter Bridge (b) is the Half Bridge and (c) is the Full Bridge and Transducers

For our study we used the Quarter Bridge and use the Strain Gauge values to decide the position of the

connecting wires The Strain indicator is shown in figure 3-4

Fig 3-4 Vishay Micro-Measurements Model P3 Strain Indicator and Recorder

44

Input Connections Tool Free eccentric lever release

4-channel input

Wire diameter16-28AWG

Bridge Configurations Quarter- Half- and Full Bridge

Bridge Impedance 60-2000Ω

Display 128 64 pixel FSTN positive gray LCD

Data Conversion AD Converter filter

Measurement Range Resolution Strain Range plusmn155mVV

Resolution plusmn00005mVV

Measurement Accuracy plusmn01 of reading plusmn3 counts

Gage Factor Control 0500-9900

Balance Control Software either manual or automatic

Bridge Excitation 15VDC nominal

Communication Interface USB Cable Included

Data Storage Removable Media Card

Shunt Calibration Across bridge completion resistors controlled

by software When Gage Factor=200

120Ω350Ω1000Ω

Analog Output Value 0 to 25V max

Ranges plusmn320 microε plusmn3200 microε plusmn32000 microε

Error 05 output voltage +5mV

Max Error 14 output voltage + 20mV

Update rate 480 samplessec

Output Load 2000Ω

Power Battery Two Alkaline D cells

Battery life 400 hours typ

USB 5V 100mA

Operational Environment Temperature 0-50

Humidity Up to 90 Non-condensing

Case Aluminum Alloy

Size and Weight 228times152times152(mm) 20(kg)

Table 3-2 Vishay Micro-Measurements Model P3 Strain Indicator and Recorder Specs

45

323 Strain Gauge

The strain gaugersquos main basic principle is to use a resistancersquos characteristics to measure the strain

The inside connections of the strain indicator are shown in figure 3-5

Fig 3-5 Inner Connections

As shown above this is a quarter-bridge connection We connect equal-length 3 wires to the 2

connections allowed by the strain gauge wire 1 and 3 can be used to cancel out the effects of temperature

to the resistance and because of the addition of wires 1 and 3 wire 2 can directly measure the experiment

results from the strain gauge and therefore the strain developed with no influence of temperature

If there were no two measuring leads then the relations will be

R 4 =R g +2R L

Where Rg is the Strain Gauge Value and RL is the wire resistance then

4

4

R

R=

Lg

g

RR

R

2

=

gL

gg

RR

RR

21

amp

4

4

R

R=

g

g

R

R(1- L)

Where L is the Signal Loss Factor and so

L =gL

gL

RR

RR

21

2

g

L

R

2R if

g

L

R

2Rltlt1

46

(Actual Value R g =120R L =08g

L

R

2Ris always much smaller than 1)

R 4 =R g +2R LR 2 =R 3 =rR gR 1 =R g 32 RR =0

V 0 =V 2)1( r

r

(

4

4

R

R-

1

1

R

R)

The first term describes loss attenuation effects second term describes loss of balancing capabilities

effects

V 0 =V 2)1( r

r

[

)2

(Lg

g

RR

R

+

T

Lg

g

RR

R

)

2( + T

Lg

L

RR

R

)

2

2( -(

g

g

R

R) T ]

The first term describes loss attenuation effects and loss of balancing capabilities effects the second

third and fourth terms describe the temperature effects on the wire

For the three-wire method we have

L =gL

gL

RR

RR

1

g

L

R

R if

g

L

R

Rltlt1

V 0 =V 2)1( r

r

[

)(Lg

g

RR

R

+

T

Lg

g

RR

R

)( + T

Lg

L

RR

R

)

2( -

T

Lg

g

RR

R

)( - T

Lg

L

RR

R

)

2( ]

V 0 = V2)1( r

r

)(

Lg

g

RR

R

In the last four terms inside parenthesis we can see the effects of temperature being cancelled out and the

effect on first term is not great so this is the reason why in our research we use three wires

47

324 Specimen Measurements

The tensile specimens used in this research are compliant of ASTM E8 Tensile parameters as shown

in figure 3-6

Fig 3-6 Tensile Specimen

Diameter

D(mm)

Gauge

Length

G(mm)

Smallest

Arc

Radius

R(mm)

Shortest

Area

A(mm)

Total

Length

L(mm)

Clamping

Area

Length

B(mm)

Clamping

Area

Diameter

C(mm)

Bar 125 02 625 01 gt10 gt75 ~ 145 ~ 35 20

Table 3-3 Specifications for Round Bar

33 Experiment Procedure

1 Attaching the Strain Gauge to the Tensile Specimen

(1) Prepare 1 ASTM E8 compliant tensile specimen round bar as shown in figure 3-7

(2) Prepare Strain Gauge as those described in table 3-4

(3) Prepare other consumables and adhesive agent such as epoxy adhesive or

cyanoacrylate adhesive as shown in figure 3-8

48

Fig 3-7 Actual Tensile Specimen

Fig 3-8 Other Materials Used (Such as Alcohol gauze transparent tape adhesive)

Gage Type

EA-06-120LZ-120E

Resistance in ohms at 24∘C

1200plusmn03

Gage Factor at 24∘C

2075plusmn05

Transverse Sensitivity at 24∘C

(+07plusmn02)

Table 3-4 Specifications for Strain Gauge

2 Attaching Strain Gauge

As shown in following figures we shall explain the attachment of the strain gauge

(1) Use sand paper and a rasp to clean thoroughly the surface where the strain gauge will be

attached to

49

(a)

(2) Use alcohol to wash the surface where the strain gauge will be attached and use gauze to rub

it off

(b)

(3) Find a clean surface and clean it with alcohol and gauze

(c)

(4) Place the strain gauge in the clean surface Use a piece of transparent tape on top of the strain

gauge after securely placed rip it off the surface carefully

50

(d)

(5) Use a piece of white paper to mark the place where the strain gauge will be attached and in

this way we can make sure that the strain gauge will be placed as horizontally and vertically

correct as possible

(e)

(6) In the place where we had our mark place the strain gauge

(f)

(7) Carefully lift one side of the tape and apply some of the adhesive agent to both the strain

gauge and specimenrsquos surface

(g)

51

(8) We need to make sure that the gauge and the specimen will be firmly attached so we gently

apply pressure with our thumb

(h)

(9) After the adhesive is fully dry we can carefully rip off the tape

(i)

(10) We need to do the whole process twice one for the horizontally placed strain gauge and one

for the vertically placed strain gauge

52

(j)

(11) We now proceed to solder the wires to the strain gauge

(k)

(12) After soldering we use a Volt Multimeter to measure that there is no contact between wires

If there is none then the specimen is ready for testing

(l)

(13) We now need to measure a 5cm distance and mark it to check and compare the elongation

before and after the tensile testing

(m)

53

Fig 3-9 Specimen-Strain Gauge Process

3 Tensile Test

(1) Enter the computer application that controls the tensile testing machine

(2) Turn on the tensile testing machine main switch

(3) Adjust the hydraulic pump to go back to its original position

(4) Bring the lowering motor down to a distance enough so as to attach the tensile specimen to the

system open the clamps and secure the specimen

(a)

(5) Connect all the necessary wires to the strain indicator equipment

54

(b)

(6) Start the ascending motor and wait for the expansion

(c)

Fig 3-10 Specimen-Tensile Testing Process

4 Start the Test

(1) Enter the software application and enter some variables needed for the experiment in the

specific screen

(2) Go back to the main screen and press the [測試] (measure) button to start the test and auto

recording in the software

(3) After the specimen breaks the mechanical device will automatically stop and ask the user to

enter the total displacement We take out the specimen from the testing machine and adjust the

machinersquos position back to its original position

(4) Save the results information

(5) Record the results from the strain indicator

34 Results

From this experiment we can get the Poissonrsquos Ratio Youngrsquos Modulus and Yield Strength etc and

because of the slippage phenomenon in the clamp at the moment of the test then the Elastic Limit will

display some yield phenomena So omit any undesirable results we just take the Yield portion of the

results as reference

In the process of the experiment the most important part to attend to is the attaching of the strain

gauge because the gaugersquos purpose is to measure the strain developed during the test and this strain

might be very small If the gaugersquos angle change during the test ie is not well attached this will affect

the accuracy of the measurements of Poissonrsquos ratio and Youngrsquos modulus

55

The materials provided by the manufacturer are SUM 23 and SUM 43 steel round bars and these two

types of materials have been through different heat treatment processes so they can be sub-divided

further into untreated material heat-treated material and black surface heat treated material for the two

materials with heat treatment the treatment process and finished are different In the end we only have

the mechanical properties that were calculated after our research of these materials

All of the specifications are identical to those shown in figure 3-6

341 SUM 23

Fig 3-11 SUM 23 Untreated Material

Number 7 10

Hardness(HRB) 74 75

Yield Stress (MPa) 448 440

Tensile Strength (MPa) 544 560

Poissonrsquos Ratio 029 027

Youngrsquos Modulus (GPa) 203 210

Cut-off Area Shrinking () 42 41

Elongation () 1125 1011

Table 3-5 Mechanical Properties of SUM 23 Untreated

56

Stress-Strain Diagram

(a)

(b)

57

Fig 3-12 Stress-Strain Diagrams for (a) 7 Round Bar and (b) 10 Round Bar

Cut-Off Area

(a)

(b)

Fig 3-13 Cut-Off Area of (a) 7 Round Bar and (b) 10 Round Bar

58

SUM 23 Nickel Round Bar

Fig 3-14 SUM 23 Nickel Material

Number 1 2 3 4

Hardness(HRB) 48 50 49 48

Yield Stress (MPa) 370 370 380 400

Tensile Strength (MPa) 455 451 450 450

Poissonrsquos Ratio 028 046 029 026

Youngrsquos Modulus (GPa) 243 303 246 206

Cut-off Area Shrinking () 803 803 726 601

Elongation () 566 65 602 647

Table 3-6 Mechanical Properties of SUM 23 Nickel

59

Stress-Strain Diagram

(a)

60

(b)

(c)

(d)

61

Fig 3-15 Stress-Strain Diagrams for (a) 1 Round Bar (b) 2 Round Bar (c) 3 Round Bar and (d)

4 Round Bar

Cut-Off Area

(a)

(b)

62

(c)

(d)

Fig 3-16 Cut-Off Area of (a) 1 Round Bar (b) 2 Round Bar (c) 3 Round Bar and (d) 4 Round

Bar

63

SUM 23 Black Surface Round Bar

Fig 3-17 SUM 23 Black Surface Material

Number 1 2 3

Hardness(HRB) 51 50 51

Yield Stress (MPa) 378 371 369

Tensile Strength (MPa) 467 465 464

Poissonrsquos Ratio 03 016 04

Youngrsquos Modulus (GPa) 215 266 266

Cut-off Area Shrinking () 986 94 848

Elongation () 748 805 761

Table 3-7 Mechanical Properties of SUM 23 Black Surface Material

64

Stress-Strain Diagram

(a)

(b)

65

(c)

Fig 3-18 Stress-Strain Diagrams for (a) 1 Round Bar 2 Round Bar and (c) 3 Round Bar

Cut-Off Surface

(a)

66

(b)

(c)

Fig 3-19 Cut-Off Surface of (a) 1 Round Bar 2 Round Bar and (c) 3 Round Bar

67

342 SUM 43

Fig 3-20 Untreated SUM 43 Untreated Material

Number 1 5

Hardness(HRB) 76 75

Yield Stress (MPa) 572 594

Tensile Strength (MPa) 743 785

Poissonrsquos Ratio 027 029

Youngrsquos Modulus (GPa) 200 202

Cut-off Area Shrinking () 338 2944

Elongation () 857 894

Table 3-8 Mechanical Properties of SUM 43 Untreated

68

Stress-Strain Diagrams

(a)

(b)

Fig 3-21 Stress-Strain Diagrams for SUM 43 (a) 1 Round Bar and (b) 5 Round Bar

69

Cut-Off Area

(a)

(b)

Fig 3-22 Cut-Off Area of SUM 43 (a) 1 Round Bar and (b) 5 Round Bar

70

SUM 43 Nickel Round Bar

Fig 3-23 SUM 43 Nickel Material

Number 4 5

Hardness(HRB) 51 50

Yield Stress (MPa) 1580 1544

Tensile Strength (MPa) 1639 1625

Poissonrsquos Ratio 03 028

Youngrsquos Modulus (GPa) 194 201

Cut-off Area Shrinking () 1697 137

Elongation () 376 265

Table 3-9 Mechanical Properties of SUM 43 Nickel

71

Stress-Strain Diagrams

(a)

(b)

Fig 3-24 Stress-Strain Diagrams for (a) 4 Round Bar and (b) 5 Round Bar

72

Cut-Off Area

(a)

(b)

Fig 3-25 Cut-Off Area of (a) 4 Round Bar and (b) 5 Round Bar

73

SUM 43 Black Surface Material

Fig 3-26 SUM 43 Black Surface Material

Number 3 5

Hardness(HRB) 56 56

Yield Stress (MPa) 1416 1361

Tensile Strength (MPa) 1591 1402

Poissonrsquos Ratio 029 031

Youngrsquos Modulus (GPa) 200 202

Cut-off Area Shrinking () 139 124

Elongation () 24 24

Table 3-10 Mechanical Properties of SUM 43 Black Surface Material

74

Stress-Strain Diagrams

0 2 4 6 8 10 12 14

-200

0

200

400

600

800

1000

1200

1400

1600

1800

應力 (MPa)

應變()

(a)

0 2 4 6 8 10

-200

0

200

400

600

800

1000

1200

1400

1600

應力

(MPa)

位移 ()

(b)

Fig 3-27 Stress-Strain Diagrams for (a) 3 Round Bar and (b) 5 Round Bar

(Note These curves were formulated using Visual Solutions Inc VisSim Software)

75

Cut-Off Area

(a)

(b)

Fig 3-28 Cut-Off Area of (a) 3 Round Bar and (b) 5 Round Bar

76

The force value (N) was retrieved from the Universal Testing Machine

The Poissonrsquos Ratio (ε) is calculated as

ε =

the values for the Poissonrsquos Ratio are in average around 0297

The Youngrsquos Modulus (E) is calculated as

E =

Where

Stress =

Cross-sectional Area =

where D is the Diameter

The value for D was in average around 1258 mm

The values shown by the computer because there is Slippage phenomena between the Clamp and the

specimen will not be taken into consideration for the elongation strain and Youngrsquos modulus and we will

refer to the values that we have meticulously calculated

77

Chapter 4 AR COATING IN DEPTH

41 Experimentrsquos Purpose and Principles

By means of a vacuum chamber and several other instruments we intend to apply Anti-Reflective

Coating using deposition process to a laser diode and in this way reduce its refraction so as to make it

lose less light in the process of amplification and we can control certain wavelengths we want produced

for certain desired applications in our case we are attempting to re-create a Bose-Einstein Condensate

An optimal BEC apparatus is shown in figure 4-1

Fig 4-1 BEC Apparatus

The main point of this experiment is to build a vacuum chamber system attach all the instrumentation

needed (Vacuum pump deposition meter and voltmeter) and use it to apply AR coating to a laser diode

After we have accomplished the AR coating other team will be in charge of designing the BEC apparatus

and use the results of our research

78

42 Experimentrsquos Equipment

421 Vacuum Chamber

For this research we designed a vacuum chamber whose main body is shown in figure 4-2 Its

dimensions are

Width 240 mm

Length 240 mm

Height 200 mm

Outer Diameter 4 in

Inner Diameter 15 in

Fig 4-2 Vacuum Chamber Main Body

The chamber is made up of 6 pass ways pass way A is the connection with the Laser Deposition

Equipment pass way B is the connection with the Turbo Pump and pass way C is for the connection with

the Deposition Source

A

C

B

79

Pass way C is for the deposition source as mentioned above This is a system where a thermal

resistance is heated by passing a high current through it which heats up a filament boat (made of tungsten)

where the material to be evaporated is place We control the temperature as such that the material will

evaporate and the heat will not cause the filament boat to crack

Because P = Isup2 R (where P is power I is current and R is resistance) to avoid the current to flow

where it is not desired we decided that the material for the Thermocouple shown in figure 4-3 should be

Copper ᴓ 63 mm We choose it that way because Copper has very good heat dissipation characteristics

and the resistance value is low It can reduce the value of the current enough to make the thermocouple to

create heat

Fig 4-3 Thermocouple

To the thermocouple we attach the tungsten filament boat We need to take notice of materials to be

used in this design because when using high current the tungsten filament boar will heat up and so the

material must be able to keep up with the heating potential of tungsten and has a low coefficient of heat

dissipation to avoid the tungsten to fail when heating up and therefore not evaporating Considering all

this we decide to use Stainless Steel

Because this clamp will be assembled inside the chamber after many revisions it was determined it

will have the shape shown in figure 4-4

Fig 4-4 Filament Boat Clamp Design

80

For the tungsten filament boat we bought the product from a distributor The dimensions are

Length 100 mm

Width 10 mm

Height 1 mm

Our thermocouple is 15 in but the pass way C is 4 in so we need to attach a Flange that connects

15in to 4in Because these specifications are quite difficult to achieve by Milling we had to use

electrical wire cutting

For the laser clamping system where the laser that is going to be AR coated will be placed will be

connected to pass way A the assembly is shown in figure 4-5 below

Fig 4-5 Cover Assembly

For this design we used an O-ring instead of a gasket so as to save time The design of the assembly

where the laser will be placed is shown in figure 4-6

Fig 4-6 Upper Cover Inner Assembly

D

E

F

81

Point D is the plate in the assembly where the laser diode will be fixed Because of the easy

processing we decide to use Aluminum and it is screwed to the top cover Point E is the connection for

the Quartz crystal resonator and it is designed in the same as point F in this way the results of the quartz

microbalance system will be more accurate in real time Point F is the final resting place for the laser

diode We use a Thor Labs Base with dimensions of ᴓ 9mm and ᴓ 56mm for two different size laser

diodes It just needs to be plugged in for easy installation

From figure 4-6 we know that the system needs signal system connections and because of the

change in temperature inside the chamber this could affect the functioning of the quartz microbalance so

we also need to install water tubes for cooling This is shown in figure 4-7 below

Fig 4-7 Diagram of Upper Cover Connections

In figure 4-8 we show the Feed through connections and their functions

Fig 4-8 Feed through Diagram

82

1 SQM-160 wire 5 Laser Connection 1 (Vin)

2 SQM-160 (G) 6 Laser Connection 2 (G)

3 K-Type-1 7 Laser Connection 3 (PD)

4 K-Type-2 8 Not In Use

The fully assembled chamber is shown in figure 4-9

Fig 4-9 Fully Assembled Chamber

422 Quartz Crystal Microbalance

For measuring the deposition on our target for coating we used the Inficon SQM-160 RateThickness

Monitor It is an easy to use instrument for measuring many types of thin-film coatings as shown in

figure 4-10

(a) Front Panel (b) Back Panel

Fig 4-10 Inficon SQM-160

83

Table 4-1 shows the technical specifications for this equipment

Number of sensors 2 Standard 4 additional optional

Sensor Frequency Range 40 MHz ~ 60 MHz

Reference Frequency Accuracy 002

Thickness Display Resolution 1 Aring

Thickness Resolution 015 Aring (Std) 0037 Aring (Hi Res)

Density of Stored Films 05-9999 gmcc

Tooling 10-399

Z-Factor 010-1000

Final Thickness 0000-9999k Aring

Measurement Period 15 to 2 sec

Simulation Mode Yes

Frequency Mode Yes

Rate Resolution 011 Arings

Dual Crystal Yes

Etch Mode Yes

Crystal Tooling 10-399

Crystal Fail Min Max 40 to 60 MHz 41 to 61 MHz

Power 100-120 200-240~plusmn10 nominal 20W

Operation Environment 0degC ~ 50degC

0 ~ 80 RH non-condensing

0 ~ 2000 meters

Class 1 Equipment

Pollution Degree 2

Rack Dimensions 885mm x 2127mm x 1969mm

Weight 27 kg

Table 4-1 Inficon SQM-160 RateThickness Monitor Specs

84

To the SQM-160 we need to connect an Oscillator We use the Sigma Instruments Remote Oscillator

Ser No 2 268 as shown in figure 4-11

Fig 4-11 Sigma Instruments Remote Oscillator

The connections diagram is shown in figure 4-12

Fig 4-12 SQM-160 Connections Diagram

85

423 Turbo Pump

For our experiments we used the Pfeiffer TCP 015 Electronic Drive Unit shown below in figure 4-13

Table 4-2 shows the technical specifications for this equipment

(a) Front Panel (b) Back Panel

Fig 4-13 Pfeiffer TCP 015 Electronic Drive

Connection Voltage (100V) 90-112

Mains Frequency 5060 Hz

Start-up Current 22 A

Nominal Frequency 1500 Hz

Rotation Speed 10V = 1500Hz plusmn2

Analog Output Current 10 V = 25 A plusmn 5

Rotation Speed Switchpoint 750 Hz

Works Setting 8 min

Permissible Ambient Temperature 0degC ~ 40degC

Dimensions Front Panel 1285mm x 1063mm

Insertion Length 227mm

Weight 27 Kg

Table 4-2 Pfeiffer TCP 015 Electronic Drive Specs

86

The connections diagram is shown in figure 4-14

Fig 4-14Connections Diagram for Pfeiffer TCP 015

To measure the pressure inside the chamber we use the Granville Phillips 375 Convectron Vacuum

Pressure Controller shown in figure 4-15

(a) Front Panel (b) Back Panel

Fig 4-15 Granville Phillips 375 Convectron

87

Its dimensions are shown in figure 4-16

Fig 4-16 Dimensions of Convectron

Table 4-3 shows the technical specifications for this equipment

Table 4-3 Granville Phillips 375 Convectron Vacuum Pressure Controller Specs

88

424 Multimeter

For our experiment we used the Keithley 2000 Digital Multimeter as shown in figure 4-17

(a) Front Panel (b) Back Panel

Fig 4-17 Keithley Model 2000 6-12-Digit Digital Multimeter

Its technical specifications are shown in table 4-4

Table 4-4 Keithley Model 2000 6-12-Digit Digital Multimeter Specs

89

43 Experiment Procedure

1 Connecting together the equipment and the chamber

(1) We first connect the resonator to the thickness monitor and connect the other side to the

chamber

(2) We now connect the flexible tubes to the turbo pump on one side and to the chamber on the

other

(3) We need to check that tubes are tightly connected to avoid any leaks in the vacuum pumping

process which will not allow us to get to our goal of Torr As shown in figure 4-18

(4) Connect the convectron to the system as shown in figure 4-19

Fig 4-18 checking for leaks using alcohol

Fig 4-19 Convectron attached to System

90

(5) Attach the clamps of the Multimeter to the bottom of the chamber as shown in figure 4-20

(6) Place the Quartz crystal in place

(7) Close tight vacuum chamber

(8) Connect all electrical appliances to power source

Fig 4-20 Multimeter Connections

2 Starting up the System

(1) We turn on all the devices as such Check all systems are ready to function Reset all values

that might be left over from previous tests

(2) Start the thickness monitor and set all values for this experiment In our case we got to testing

the system but not actual coating So we used the simulation mode of the thickness monitor as

shown in figure 4-21

Fig 4-21 Simulation Mode

91

(3) Start the turbo pump Make sure the lid on the vacuum chamber is tightly closed

(4) Start convectron and record initial pressure

(5) Start Multimeter and record initial current

3 Coating Process

(1) If we have the deposition material inside the filament boat the power source for the high

current must be started as well

(2) Record all initial values for thickness current pressure

(3) For an ideal experiment we need a thickness of around 101 nm a pressure of Torr and

a current of 300 A

44 Results

From previous experiments we have shown that we can turn a LED into a laser by means of AR

Coating In figure 4-22 shown below we can compare the actual results of a Diode before and after AR

coating From the blue line we can see that when the diode is at a current of 15mA its light will change

from LED to laser and if we look at the red line its critical current is around 30 to 35 mA

Fig 4-22 AR Coating Comparison for Laser Diodes

This means that the light emitted is not as strong as if the diode had been coated because inside the

chamber there must be some excitation first so the reflectivity of both sides inside the diode must be high

So because of the coating in one of the sides we have opened a door and let the light come out so the

critical current is risen as such and will be higher value than that of before the coating

92

In the following figures we can see the difference between before and after coating in a material The

thickness is around 1016 nm for this material

Fig 4-23 Before Coating

Fig 4-24 After Coating

93

Chapter 5 CONCLUSIONS AND RECOMMENDATIONS

51 Conclusions

For the first part of this independent study taking into consideration the data that came out of our

research and that sent by the provider we can say

1 SUM 23 after heat treatment will unexpectedly develop cracking in the middle of the tensile

testing process and suddenly break

2 Itrsquos possible that in the process of heat treatment to the SUM 23 material the treatment was not

uniform and this will create a pre-loaded moment force on one side that pushes on the other side

of the specimen resulting in material deformation

3 In the process of attaching the strain gauges to the materials it is very easy to make errors due to

poor adhesion or sudden removal in the tensile testing process

For our second part of the independent study the following can be made

1 At the beginning of this independent study we had no idea what Bose-Einstein Condensate was

or what was its purpose After much literature we finally comprehended the basic principles to

put into practice for our research

2 Our systemrsquos basic working principles and equipmentrsquos complexity are a little difficult to grasp

but hopefully we were able to understand enough of it

3 Theoretically from relation between the power and current we can know the advantages and

disadvantages of AR Coating

4 We were able to assemble the system and run test on its functions Even though we were able to

do this there is still much more work left to do with this system

52 Recommendations

For the Tensile Testing the following can be said

1 Ask the provider to check on the process of heat treatment on the SUM 23 material and give

them the information we have gathered through our test so they can correct for the mechanical

properties found if any change is needed

2 To avoid the problem of the inaccuracy of the poor adhesion of strain gauges we can attach

multiple strain gauges to the same one specimen so as to correlate data and improve our results

For the AR Coating the following can be said

1 We need to make sure that there are no physical defects on the main body of the chamber so as to

achieve maximum efficiency in the vacuum process If there was then the vacuum will arrive to

certain point and then start to decrease

2 It would be preferable to add some sort of visual aid that will allow the user to check the inside of

the chamber without actually opening it This will help us determine at what times we should

manipulate the current to better evaporate the substrate

94

REFERENCES

[1] A L Window Strain Gauge Technology Elsevier Applied Science London and New York 2nd

Edition 1992

[2] CC Perry and HR Lissner Strain Gauge Primer McGraw-Hill Book Co Inc New York 1955

[3] James W Dally William F Riley McGraw-Hill 1978

[4] University of Colorado Boulder BEC - What is it and where did the idea come from

httpwwwcoloradoeduphysics2000becwhat_is_ithtml

[5] Ultraslow Light amp Bose-Einstein Condensates Two-way Control with Coherent Light amp Atom

Fields Harvard Hau Lab Dr Lene Vestergaard Hau Optics amp Photonics News 16 1995

[6] The Art of Taming Light Ultra-slow and Stopped Light Harvard Hau Lab Dr Lene

Vestergaard Hau Europhysics News 2004

[7] Nonlinear Optics Shocking Superfluids Harvard Hau Lab Dr Lene Vestergaard Hau Nature

Physics 2007

[8] Model P3 Strain Indicator and Recorder Instruction Manual Vishay Micro-Measurements 2005

[9] Granville-Phillips Series 375 Convectron Vacuum Gauge Controller Instruction Manual Brooks

Automation 2008

[10] Effect of Film Thickness on the Validity of the Sauerbrey Equation for Hydrated Polyelectrolyte

Films Vogt Lin Wu White 2004

[11] Quartz Crystal Microbalance Study of DNA Immobilization and Hybridization for DNA Sensor

Development Chang Zhao 2008

[12] Installation of Strain Gages with SR-4 PrecoatAdhesive Vishay Micro-Measurements 2005

[13] Strain Gauge Measurement ndash A Tutorial National Instruments 1998

[14] Correlation between Vickers Hardness Number and Yield Stress of Cold-Formed Products

Yavuz Tekkaya

[15] httpsenwikipediaorg

Page 16: PC Hinge Materials Testing and AR Laser Diode Coating

16

213 Ultimate Tensile Strength and Breaking Strength

After materials undergo yield they keep lending strength and hardening phenomena occurs (work

hardening) on the material and the external load increases When it has reached the highest point this is

called the Ultimate Tensile Strength (UTS) as shown in Fig2-1 The UTS is defined as

σUTS =

Where Pmax is the load at the materialrsquos ultimate tensile strength point and Ao is the original cut-off

area For brittle materials the ultimate tensile strength is the most important mechanical property for

ductile materials the ultimate tensile strength is not commonly used for industrial and designing purposes

because upon arriving to this value the material already has forgone great plastic deformation After the

specimen goes through UTS there will be necking phenomena which is a mode of tensile deformation

where relatively large amounts of strain localize disproportionately in a small region of the material It

results from instability during tensile deformation when a materialrsquos cross-sectional area decreases by a

greater proportion than the material strain hardens The specimen continues to elongate until it finally

breaks and the load at this point is called Breaking Strength The breaking strength is defined as the

greatest stress in tension that a material is capable of withstanding without rupture

Where Pf is the load at the materialrsquos breaking strength point and Ao is the original cut-off area

214 Poissonrsquos Ratio (ν)

For elastic deformation when materials are compressed in one direction they tend to expand in the

other two directions perpendicular to the direction of compression This is called the Poissonrsquos Effect

The Poison Ratio is a measure of the Poissonrsquos effect It is the ratio of the fraction of expansion divided

by the fraction of compression for small values of these changes

ν=-

215 Strain Gauge Basic Principles

The strain gauge is a device used to measure the strain of an object Itrsquos an elongated metal resistor

which is attached to the specimen being measured and when the specimen is under strain and starts to

deform the strain gauge will have a change in the resistance With the change in value we can calculate

the elementrsquos strain or elastic modulus and the Poissonrsquos ratio

It takes advantage of the physical property of electrical conductance and its dependence on the

conductorrsquos geometry When the electrical conductor (the specimen being tested) is stretched within the

limits of elasticity such that it does not break or deform plastically it will become narrower and longer

17

which increases the electrical resistance through-out From the measured resistance of the strain gauge

the amount of stress may be inferred by using the relations

R=

Where R is the original resistance value is the electrical resistivity lo is the original length of the

conductor and Ao is the original cross sectional area of the conductor If after the application of tension

the change in length is Δl let the length of the specimen be l = l + Δlo and the tension is the same

through-out So

And the resistance is

The Gauge Factor is the ratio of relative change in electrical resistance to the mechanical strain in

other words it is the relative change in length It is defined as

The strain gauge was invented in 1938 by Edward E Simmons and Arthur C Ruge and the most

common type consists of an insulating flexible backing which supports a metallic foil usually made of a

brass-nickel alloy It is attached to the specimen by a suitable adhesive As the object is deformed the foil

also deforms and this causes the electrical resistance to change Then this is usually measured using a

Wheatstone bridge shown below and is related to the strain by the Gauge Factor

Fig2-3 Basic Structure of Strain Gauge

18

Fig 2-4 Strain gauge attached to Wheatstone bridge

22 Hardness Testing Basic Principles

221 Brinell Scale BHN

The Brinell Scale characterizes the indentation hardness of materials through the scale of penetration

of an indenter loaded on a material specimen The typical test uses a 10mm diameter steel ball as indenter

(usually of value equal to BHN450) with a 29kN force For softer materials smaller force is used The

indentation is measured and BHN is calculated using the relation

BHN =

radic

Where F is the applied force usually within the range of 100 250 500 750 1000 1500 2000 2500

and 3000 kgf D is the diameter of indenter usually within the range of 5mm or 10mm plusmn0005 margin

and d is the diameter of indentation usually around 2mm Its units are of Kgmmsup2 but are not normally

written

First proposed by Swedish engineer Johan August Brinell in 1900 it was the first widely used and

standardized hardness test in engineering and metallurgy although the large size of indentation and

possible damage to specimen limits its usefulness

Fig 2-5 Brinell Indentation Fig2-6 Brinell Hardness Tester

19

222 Rockwell Scale HR

The Rockwell scale is a hardness scale based on the indentation hardness of a material The Rockwell

test determines the hardness by measuring the depth of penetration of an indenter under a large load

compared to the penetration made by a preload The indenter is forced into the specimen under a

preliminary load When equilibrium is reached a measuring device follows the movements of the

indenter and responds to changes in depth of penetration of the indenter While the preload is still being

applied additional major load is applied resulting in increased penetration When equilibrium is reached

again the major load is removed but the preload is maintained Removing the major load allows partial

recovery and reduces the depth of penetration The permanent increase in depth of penetration resulting

from the application and removal of the major load is used to calculate the Rockwell number using the

relation

HR = E ndash e

Where E is a constant depending on the form of the indenter 100 units for diamond indenter and 130

units for steel ball indenter e is the permanent increase in depth of penetration due to the major load

measured in units of 0002mm

Fig 2-7 Rockwell Indentation

When testing materials indentation hardness is related linearly to the tensile strength The important

relation permits economically important nondestructive testing of bulk metal deliveries with lightweight

equipment like the Rockwell tester shown below in figure 2-7

Fig 2-8 Rockwell Hardness Tester

20

There are different scales denoted by a single letter that use different loads or different indenters

The result is a dimensionless number denoted as HR X where X will be the letter denoting the scale as

shown below in table 2-1

Table 2-1 Rockwell Hardness Test Scale

Differential depth hardness measurement was first conceived in 1908 by Viennese professor Paul

Ludwik It eliminated the errors associated with the mechanical imperfections of the system such as

backlash and surface imperfections in the specimen Rockwell testing has an advantage over Brinell

testing because the latter was slow itrsquos not useful on fully hardened steel and left too large an impression

to be considered nondestructive

The tester was co-invented by Hugh M Rockwell and Stanley P Rockwell The requirement for this

tester was to quickly determine the effects of heat treatment on steel bearing races

21

223 Vickers Hardness Test HV

This is a type of microindentation hardness test where a diamond indenter of specific geometry is

impressed into the surface of the test specimen using a known applied force ranging from 10 to 1000

grams This type of tests usually has forces of 2N and produce indentations of about 50μm They can be

used to observe changes in hardness on the microscopic scale It is difficult to standardize the

microhardness measurements because it has been found that the microhardness of almost any material is

higher than its macrohardness The values also vary with load and work-hardening effects of materials

The Vickers test is often easier to use than other hardness tests because the required calculations are

independent of the size of the indenter and the indenter can be used for all materials It can be used for all

metals and has one of the widest scales among hardness tests The unit of the Vickers test is denoted as

HV and can be converted to units of Pascal (Pa) but it is not a measurement of pressure The hardness

number is determined by the load over the surface area of the indentation and not the area normal to the

force

A square-based pyramid shaped diamond is use as the indenter It has been established that the ideal

size of a Brinell impression was 38 of the ball diameter As two tangents to the circle at the ends of a

chord 3d8 long intersect at 136plusmn05deg it was decided to use this as the angle of the indenter giving an

angle to the horizontal plane of 22deg on each side The HV number is determined by the ratio FA where F

is the force applied to the diamond in kgf and A is the surface area of the resulting indentation in mmsup2 A

can be determined by the relation

A =

Where A is the surface area of indentation and d is the average length diagonal left by the indenter

This can be approximated as

A =

Then the Vickers Number is

HV =

=

Vickers hardness number is reported as xxxHVyy or xxxHVyyzz (if duration of applied force differs

from 10s to 15s) where xxx are replaced by the hardness number yy is the load in kg and zz indicates

loading time The values are generally independent of test force

The test was developed in 1921 by Robert L Smith and George E Sandland at Vickers Ltd as an

alternative to Brinell method to measure the hardness of materials

22

Fig 2-9 Vickers Indentation Fig 2-10 Vickers Hardness Tester

23 AR Coating

231 Bose-Einstein Condensate

The Bose-Einstein Condensate or BEC is a state of matter of a dilute gas of bosons cooled to

temperatures very near absolute zero around 0K or -27315degC Under such conditions a large fraction of

the bosons occupy the lowest quantum state where the quantum effects become apparent on a

macroscopic scale This gave birth to the Bose-Einstein Statistics which are the rules that govern the

behavior at this state It is one of the two possible ways in which a collection of indistinguishable particles

may occupy a set of available discrete energy states The aggregation of particles in the same state

accounts for the cohesive streaming of laser light and the frictionless creeping of superfluid helium (an

application discussed later) Bose and Einstein recognized that a collection of identical and

indistinguishable particles can be distributed this way This theory applies only to those particles not

limited to single occupancy of the same state particles that do not obey the Pauli Exclusion Principle

restrictions Such particles are the Bosons named after the statistics that correctly describe their behavior

This phenomenon was first predicted by Satyendra Nath Bose around 1924 when he considered how

groups of photons behave He then asked Albert Einstein for help publishing his discoveries to which

Einstein agreed and gave follow up supporting these findings The resulting efforts became the concept of

a Bose gas governed by the Bose-Einstein Statistics described above Einstein demonstrated that cooling

bosonic atoms to a very low temperature would cause them to condense into the lowest accessible

quantum state resulting in a new form of matter

The first gaseous condensate we produced by Eric Cornell and Carl Wieman at the University of

Colorado at Boulder NIST ndash JILA lab sung a gas of rubidium atoms cooled to 170 nK which earned

them the 2001 Nobel Prize in physics together with Wolfgang Ketterle from MIT The transition to BEC

occurs below a critical temperature which for a uniform three dimensional gas consisting of

non-interacting particles with no apparent internal degrees of freedom is given by

23

Tc =

(

)

asymp 33125

Where Tc is the critical temperature n is the particle density m is the mass per boson h is the

reduced Planck constant k is the Boltzmann constant and ζ is the Riemann zeta function

There are two classes of elementary particles defined by whether their quantum spin is a nonnegative

integer or an odd half integer A Bose-Einstein Condensate is shown below in figure 2-11

Fig 2-11 Bose Einstein Condensate at different scales

Bosons are the particles whose quantum spin is a nonnegative integer (s = 0 1 2 etc) Examples of

bosons include fundamental particles (Higgs Boson Photons W and Z Bosons Gluons Gravitons etc)

composite particles (Mesons Hadrons Nuclei and Atoms of Carbon-12 and Helium-4) and

quasi-particles Bosons are considered force carrier particles The Bosons differ from Fermions in that

there is no limit to the number that can occupy the same quantum state This is called the Pauli Exclusion

Principle

The Pauli Exclusion Principle says that no two identical fermions may occupy the same quantum state

simultaneously in other words this means that the total wave function for two identical fermions is

anti-symmetric with respect to exchange of the particles This means that no two electrons in a single

atom can have the same four quantum numbers

Fermion is any particle characterized by Fermi-Dirac Statistics and follows the Pauli Exclusion

Principle described above Quarks Leptons and composite particles (Hadrons Nuclei and Atoms of

Carbon-13 and Helium-3) made of an odd number of these are considered Fermions It can be an

elementary particle such as the electron or a composite particle such as the protons Following the Pauli

24

Exclusion Principle only one fermion can occupy a particular quantum state at any given time If multiple

fermions have the same spatial probability distribution then at least one property of each fermion must be

different Fermions are usually associated with matter because composite fermions are key building

blocks of matter (neutrons and protons)

Fermionsrsquo behavior by the Fermi-Dirac Statistics which describes the energies of single particles in a

system comprising of many identical particles It applies to identical particles with half-odd integer spin

in a system of thermal equilibrium The particles in the system are assumed to have negligible mutual

interaction This allows the many-particle system to be described in terms of single-particle energy states

The result is the Fermi-Dirac distribution of particles over these states and includes the condition that no

two particles can occupy the same state which has considerable effect on the properties of the system

In quantum mechanics the position of an object is uncertain An object has a definite probability of

being at any given point in space This probability is encoded in the wave function mentioned earlier If

one concentrates a large number of identical bosons in a small region then it is possible for their wave

functions to overlap so much that the bosons lose their identity When this happens thatrsquos a Bose-Einstein

Condensate It is only possible at very low temperatures because at high temperatures the individual

bosons have small wave functions and move rapidly which causes them to fly apart

For now applications are still restricted because there are still some setbacks regarding BECs They

are extremely fragile they are being produced in small quantities with just a few million atoms at a time

and finally they can only be made from certain types of atoms Some examples are the atom laser Ketterle

in which a conventional light lase emits a beam of coherent photons this means they are all in phase and

can be concentrated to an extremely small bright spot BECs can slow down light as demonstrated by

Prof Lene Hau PhD in 2001 by the use of a superfluid [7] These manipulations could develop into

new types of telecommunications technology optical storage and quantum computing

BECs are related to super-fluidity and super-conductivity Super-fluidity is the state of matter in

which the behavior is that of a fluid with zero viscosity It was discovered in liquid helium but now it has

applications in astrophysics high-energy physics and theories of quantum gravity

Super-conductivity is a phenomenon of exactly zero electrical resistance and expulsion of magnetic

fields occurring in certain materials when cooled below a characteristic critical temperature A

super-conductor is shown below in figure 2-12

Fig2-12 Super Conductor

25

232 AR Coating Basic Principles

Anti-reflective (AR) coating is a type of optical coating applied to the surface of lenses and other

optical devices (in our case we planned to apply it to a laser diode) to reduce reflection This improves

the efficiency of the system since less light is lost The primary benefit is the elimination of the reflection

itself

When light the medium (glass) it will produce reflection if 100 of the light comes from the air and

enters the glass because therersquos a difference between the index of refraction some of the light will go out

and when the light is coming out of the glass into the air once again because of the difference between

index of refraction some of the light wonrsquot be able to pass through the medium

When the light makes the first trip into the glass there was a loss of about 4 in the reflection and

when the light makes the trip back outside there was another loss of about 4 so when we assume that

100 of the light interacts with the medium actually therersquos just about 92 acting (we neglect the light

absorbed by the glass around 05) To illustrate this idea please refer to figure 2-13

Fig 2-13 Simple Model for Light in Glass Medium

When we apply the AR Coating the light that enters will only have a loss of about 05 and when

making the trip back outside again only 05 of light is loss so we get the result of increasing the light

passing through up to 99 (again neglecting the light absorbed by the glass around 05) To illustrate

this idea please refer to figure 2-14

26

Fig 2-14 Simple Model for Light in Glass Medium after AR Coating

The AR Coating can reduce reflection of incoming light In the case that light hits perpendicular to

the surface of the medium the intensity of the reflection can be calculated using the Reflection

Coefficient

Where n0 and ns are the refractive indices of the first and second media respectively The value of R

varies from 0 (no reflection) to 1 (all light reflected) and is usually quoted as a percentage

Complementary to R is the transmission coefficient or Transmittance If absorption and scattering are

neglected then the value of Transmittance is always 1-R then if a beam of light with intensity I is

incident on the surface a beam of intensity RI is reflected and a beam with intensity TI is transmitted to

the medium

The optimal value is called the Optimal Index of Refraction and is described as

For glass with ns around 15 in air (n0 around 10) then the optimum refractive index will be n1 =

1225

To reduce the refraction in this case we now mean the one that is produced inside the chamber of the

Laser diode the easiest way is to apply a low reflectivity AR coating on the surface of the laser To

measure the appropriate thickness of the coating layer we can use the equations described above By

applying a coat exactly

thickness film we can assure that a certain wavelength is transmitted The

27

reflected waves from the back of the glass medium will be half a wavelength out of phase So they

interfere destructively Because all reflected waves are interfered the maximum amount of light passes

through the coating Please refer to figure 2-15 to illustrate this idea

Fig 2-15 Light Passing through AR Coat and Glass

The most common process to attain this final product is by vacuum deposition For the best coating

results we need to lower the pressure inside the vacuum system to torr

Fig 2-16 Lens without (Top) and With (Bottom) AR Coating

28

233 Laser Diode Basic Principles

A laser diode is a laser whose active medium is a semiconductor similar to that found in

light-emitting diodes (LEDs) Please refer to figure 2-17 The most common type of laser diode is formed

from a p-n junction and powered by injected electric current

Fig 2-17 Laser Diode

Laser diodes are formed by doping a very thin layer on the surface of a crystal wafer The crystal is

doped to produce the n-type region and a p-type region one above the other

By referring to figure 1-2 we can see the basic structure of a working laser When the laser diode has

a current passing through it the light will get excited inside its gain medium and then will start to

resonate this process is called pumping The current exceeds the critical current and then it comes out as

laser light Please refer to figure 1-3 Since we use an external cavity laser we need to apply the AR

coating to the diode and adjust a diffraction grating The laser light comes out the diode and bounces on

the grating making the resonance externally and this becomes the ldquocavityrdquo as shown in figure 2-18

Fig 2-18 Tunable Laser Basic Configuration

29

The most important feature of the external cavity laser is that we can adjust the wavelength easily just

by changing the diffraction gratingrsquos angle and in the end this is the output wavelength of the laser For

different wavelengths there will be different levels of visible light as shown in figure 2-19

Fig 2-19 Light Spectrum

234 Quartz Microbalance System

A Quartz Crystal Microbalance is an instrument that measures a mass per unit area by measuring the

change in frequency of a quartz crystal resonator The resonance is disturbed by the addition or removal

of a small mass due to oxide growthdecay or film deposition (which is the case in our study) at the

surface of the acoustic resonator The QCM can be used under vacuum in gas phase and more recently in

liquid environments It is useful for monitoring the rate of deposition in thin film deposition systems

under vacuum Frequency measurements are easily made with high precision

For our research we used the Sigma Instruments SQM-160 RateThickness Monitor shown in figure

2-20

Fig 2-20 Front and Back Panels of SQM-160

30

The microbalance uses Quartz as the resonator Quartz is one member of the family of crystals that

experience the Piezoelectric Effect

Piezoelectricity is the charge that accumulates in certain solid materials in response to applied

mechanical stress It means electricity resulting from pressure It was discovered in 1880 by Jacques and

Pierre Curie It is understood as the linear electromechanical interaction between the mechanical and the

electrical state in crystalline materials with no inversion symmetry It is a reversible process in that

materials exhibiting direct piezoelectricity also exhibit the reverse This means that the internal generation

of electrical resulting from applied mechanical force and vice versa

By using the piezoelectric effect we can probe as an acoustic resonance by electrical means Applying

alternating current to the quartz crystal induces oscillations This creates a shear wave We can use these

qualities to determine the resonance frequency at high accuracy

The frequency of oscillation of the crystal is partially dependent in the thickness of the crystal During

normal operation all the variables are held constant so a change in thickness correlates directly to a

change in frequency As mass is deposited or etched away the thickness increases or decreases and so the

frequency of oscillation changes accordingly With some simplifying assumptions the frequency change

can be quantified and correlated precisely to the mass change using the Sauerbreyrsquos Equation

Developed by G Sauerbrey in 1959 it is a method for correlating changes in the oscillation

frequency of a piezoelectric crystal with the mass deposited on it It is defined as below

Where f0 is the Resonant frequency Δf is the Frequency change Δm is the mass change A is the

piezoelectrically active area of the crystal q is the Density of quartz (2648 gcmsup3) and μq is the Shear

modulus of quarts(2947x gcmssup2)

Because the film is treated as an extension of thickness Sauerbreyrsquos equation only applies to systems

in which the following 3 conditions are met

Deposited mass must be rigid

Deposited mass must be distributed evenly

The frequency change

lt002

If the change is greater than 2 the Z-match method must be used to determine the change in mass

It is defined as

Where fL is the frequency of the loaded crystal fU is the resonant frequency Nq is the frequency

constant (1668x HzAring) Δm is the mass change A is the piezoelectrically active area of the crystal

31

q is the density of quartz Z is the method constant f is the density of film μq Is the shear modulus of

quarts and μf is the shear modulus of film

The Sauerbrey equation cannot be applied to systems under liquid medium

The crystals are seed crystals plated with gold on both top and bottom for applications A crystal is

shown in figure 2-21 The QCM consists of a thin piezoelectric plate with electrodes evaporated on both

sides Due to the piezoelectric effect AC voltage across the electrodes induces a shear deformation and

vice versa The electromechanical coupling provides a simple way to detect an acoustic resonance by

electrical means

The Z also called Z-factor is a constant value for different materials and it is shown together with the

density of different materials in table 2-2 below

Fig 2-21 QCM Crystals

The Oscillator of the SQM-160 is shown in figure 2-22 and the equivalent circuit for the Resonant

Oscillator is shown in figure 2-23

Fig 2-22 SQM-160 Oscillator

32

Fig 2-23 Oscillator Circuit

33

Table 2-2 Z-Ratios for Different Materials

Table 2-2 Continued

34

Table 2-2 Continued

35

Table 2-2 Continued

36

Table 2-2 Continued

37

Table 2-2 Continued

38

Table 2-2 Continued

235 Vacuum Chamber System

Vacuum Evaporation is the process of depositing thin films of materials onto surfaces The technique

consists of pumping a vacuum chamber to pressures of less than torr and heating a material to

produce a flux of vapor in order to deposit the material onto a surface The material to be vaporized is

typically heated until its vapor pressure is high enough to produce a flux several Angstrom per second by

using an electrically resistive heater or bombardment by a high voltage beam The process was invented

by Henri Nestle in 1886 for food industry

In here the system has been pumped to a vacuum of Torr When a high current is passed

through the filament boat the filament boat is heated over the desired metal evaporation temperature and

so evaporation starts When the evaporation process is finished and the metal cools down crystals

condensate in the surface of the wafer From the weight of the evaporated material the distance between

the filament boat and the wafer we are able to calculate the deposition thickness and we can also use the

mass detector follower like the Quartz crystal resonator microbalance system In the process of

evaporation we usually use a board in between the filament boat and the wafer This is because before we

arrive to the desired evaporation temperature there will be some impurities that will be vaporized in the

controlled environment so we first use a small current and the board in between to get rid of those

impurities and this raises the purity of the deposition material

39

A vacuum evaporation system is shown in figure 2-24

Fig 2-24 Vacuum Evaporation System

Rough Vacuum 760 ~ 1 torr

Medium Vacuum 1 ~ torr

High Vacuum ~ torr

Ultra-High Vacuum Lower than torr

Table 2-3 Classification of Vacuum

For our study we need to use a Turbo Pump A regular turbo pump is shown in figure 2-25

Fig 2-25 Turbo Pump

For our research we used the Pfeiffer TCP 015 Electronic Drive Unit and Granville Phillips 375

Convectron shown below in figure 2-26

40

Fig 2-26 Control and Measurement Equipment

The electronic drive controls the turbo pump and the Convectron measures the pressure inside our

chamber The turbo pump is a type of vacuum pump used to maintain high vacuum Most turbo pumps

are centrifugal When we start the pumping we need to use a mechanical pump so as to decrease the

pressure inside the system from constant atmospheric pressure to torr and then the use dispersion

pump to continue the vacuum until we get to the desired pressure We need to notice though when we

start the dispersion pump we canrsquot turn off the mechanical pump and they both need to run together If

we need to turn off the pumping we first turn off the dispersion pump wait for it to completely stop and

then turn off the mechanical pump

Our completely assembled system is shown in figure 2-27 below

Fig 2-27 Complete System

41

Chapter 3 TENSILE TESTING IN DEPTH

31 Experimentrsquos Purpose and Principles

By means of Universal testing machine and Strain gauges we were able to observe discuss and

analyze the phenomena created when a specimen of certain material is manipulated under an external load

and determine the stress strain and deformation values later we can use the graphing methods of

stress-strain diagram to describe it

The main point of this experiment is that after the tensile specimen is tested use computer analysis

and the actual strain data and after statistical adjustment make the final results report (Tensile testing

experiment is in accordance with ASTM E8)

32 Experimentrsquos Equipment

321 Universal Testing Machine

For the materials testing experiment part of this research we use a Universal Testing Machine as

shown in figure 31 The maximum load it can apply is 100 Ton After the test specimen is secured on the

device with the use of instrumentation the load exerted and the effects of this become apparent on the

specimen and even the smallest of changes can be recorded For our research we used the Chun Yen

Testing Machines Co Ltd 100 Ton Micro Computer Universal Tensile Tester

Fig 31 Universal Testing Machine

42

Table 31 shows the specifications for this machine

Max Capacity 100 Ton

Accuracy plusmn1

Tension (mm) Max Space 1150mm

Grip for Rod 20-70mm

Ram Stroke 250mm

Effective Column Interval 940mm

Crosshead Speed 300mmmin

Testing Speed 0-50mmmin

Volume of Machine 1700times1000times3350mm(LtimesWtimesH)

Volume of Control Panel 1000times800times1500mm(LtimesWtimesH)

Weight 8000kg

Power 3∮220V 20A

Computer AMD K6-2-350

OS Windows XP

Screen 15rdquo CRT

Table 3-1 Chun Yen Testing Machine Specs Table

The connections diagram is shown in figure 3-2

Fig 3-2 Diagram for System Connections

43

When the test specimen is placed when the external force is applied the Load Cell can measure the

size of the applied force and the Encoder measures the expansion rate of change The Local Controller

receives all the information from the 2 units after arranging the results they are displayed in the

computer and they can be afterwards submitted for more complex analysis such as Finite Element

Analysis and we can get the Stress-Strain Diagram

322 Strain Measurement Equipment

The equipment used in our research provides a four-channel measurement that means we can use up

to 4 strain gauges at a time to do our measurements and provides 3 different bridge arrangements as

shown in figure 3-3

(a) (b) (c)

Fig 3-3 Input Connections for Strain Indicator

Figure 3-3 (a) is the Quarter Bridge (b) is the Half Bridge and (c) is the Full Bridge and Transducers

For our study we used the Quarter Bridge and use the Strain Gauge values to decide the position of the

connecting wires The Strain indicator is shown in figure 3-4

Fig 3-4 Vishay Micro-Measurements Model P3 Strain Indicator and Recorder

44

Input Connections Tool Free eccentric lever release

4-channel input

Wire diameter16-28AWG

Bridge Configurations Quarter- Half- and Full Bridge

Bridge Impedance 60-2000Ω

Display 128 64 pixel FSTN positive gray LCD

Data Conversion AD Converter filter

Measurement Range Resolution Strain Range plusmn155mVV

Resolution plusmn00005mVV

Measurement Accuracy plusmn01 of reading plusmn3 counts

Gage Factor Control 0500-9900

Balance Control Software either manual or automatic

Bridge Excitation 15VDC nominal

Communication Interface USB Cable Included

Data Storage Removable Media Card

Shunt Calibration Across bridge completion resistors controlled

by software When Gage Factor=200

120Ω350Ω1000Ω

Analog Output Value 0 to 25V max

Ranges plusmn320 microε plusmn3200 microε plusmn32000 microε

Error 05 output voltage +5mV

Max Error 14 output voltage + 20mV

Update rate 480 samplessec

Output Load 2000Ω

Power Battery Two Alkaline D cells

Battery life 400 hours typ

USB 5V 100mA

Operational Environment Temperature 0-50

Humidity Up to 90 Non-condensing

Case Aluminum Alloy

Size and Weight 228times152times152(mm) 20(kg)

Table 3-2 Vishay Micro-Measurements Model P3 Strain Indicator and Recorder Specs

45

323 Strain Gauge

The strain gaugersquos main basic principle is to use a resistancersquos characteristics to measure the strain

The inside connections of the strain indicator are shown in figure 3-5

Fig 3-5 Inner Connections

As shown above this is a quarter-bridge connection We connect equal-length 3 wires to the 2

connections allowed by the strain gauge wire 1 and 3 can be used to cancel out the effects of temperature

to the resistance and because of the addition of wires 1 and 3 wire 2 can directly measure the experiment

results from the strain gauge and therefore the strain developed with no influence of temperature

If there were no two measuring leads then the relations will be

R 4 =R g +2R L

Where Rg is the Strain Gauge Value and RL is the wire resistance then

4

4

R

R=

Lg

g

RR

R

2

=

gL

gg

RR

RR

21

amp

4

4

R

R=

g

g

R

R(1- L)

Where L is the Signal Loss Factor and so

L =gL

gL

RR

RR

21

2

g

L

R

2R if

g

L

R

2Rltlt1

46

(Actual Value R g =120R L =08g

L

R

2Ris always much smaller than 1)

R 4 =R g +2R LR 2 =R 3 =rR gR 1 =R g 32 RR =0

V 0 =V 2)1( r

r

(

4

4

R

R-

1

1

R

R)

The first term describes loss attenuation effects second term describes loss of balancing capabilities

effects

V 0 =V 2)1( r

r

[

)2

(Lg

g

RR

R

+

T

Lg

g

RR

R

)

2( + T

Lg

L

RR

R

)

2

2( -(

g

g

R

R) T ]

The first term describes loss attenuation effects and loss of balancing capabilities effects the second

third and fourth terms describe the temperature effects on the wire

For the three-wire method we have

L =gL

gL

RR

RR

1

g

L

R

R if

g

L

R

Rltlt1

V 0 =V 2)1( r

r

[

)(Lg

g

RR

R

+

T

Lg

g

RR

R

)( + T

Lg

L

RR

R

)

2( -

T

Lg

g

RR

R

)( - T

Lg

L

RR

R

)

2( ]

V 0 = V2)1( r

r

)(

Lg

g

RR

R

In the last four terms inside parenthesis we can see the effects of temperature being cancelled out and the

effect on first term is not great so this is the reason why in our research we use three wires

47

324 Specimen Measurements

The tensile specimens used in this research are compliant of ASTM E8 Tensile parameters as shown

in figure 3-6

Fig 3-6 Tensile Specimen

Diameter

D(mm)

Gauge

Length

G(mm)

Smallest

Arc

Radius

R(mm)

Shortest

Area

A(mm)

Total

Length

L(mm)

Clamping

Area

Length

B(mm)

Clamping

Area

Diameter

C(mm)

Bar 125 02 625 01 gt10 gt75 ~ 145 ~ 35 20

Table 3-3 Specifications for Round Bar

33 Experiment Procedure

1 Attaching the Strain Gauge to the Tensile Specimen

(1) Prepare 1 ASTM E8 compliant tensile specimen round bar as shown in figure 3-7

(2) Prepare Strain Gauge as those described in table 3-4

(3) Prepare other consumables and adhesive agent such as epoxy adhesive or

cyanoacrylate adhesive as shown in figure 3-8

48

Fig 3-7 Actual Tensile Specimen

Fig 3-8 Other Materials Used (Such as Alcohol gauze transparent tape adhesive)

Gage Type

EA-06-120LZ-120E

Resistance in ohms at 24∘C

1200plusmn03

Gage Factor at 24∘C

2075plusmn05

Transverse Sensitivity at 24∘C

(+07plusmn02)

Table 3-4 Specifications for Strain Gauge

2 Attaching Strain Gauge

As shown in following figures we shall explain the attachment of the strain gauge

(1) Use sand paper and a rasp to clean thoroughly the surface where the strain gauge will be

attached to

49

(a)

(2) Use alcohol to wash the surface where the strain gauge will be attached and use gauze to rub

it off

(b)

(3) Find a clean surface and clean it with alcohol and gauze

(c)

(4) Place the strain gauge in the clean surface Use a piece of transparent tape on top of the strain

gauge after securely placed rip it off the surface carefully

50

(d)

(5) Use a piece of white paper to mark the place where the strain gauge will be attached and in

this way we can make sure that the strain gauge will be placed as horizontally and vertically

correct as possible

(e)

(6) In the place where we had our mark place the strain gauge

(f)

(7) Carefully lift one side of the tape and apply some of the adhesive agent to both the strain

gauge and specimenrsquos surface

(g)

51

(8) We need to make sure that the gauge and the specimen will be firmly attached so we gently

apply pressure with our thumb

(h)

(9) After the adhesive is fully dry we can carefully rip off the tape

(i)

(10) We need to do the whole process twice one for the horizontally placed strain gauge and one

for the vertically placed strain gauge

52

(j)

(11) We now proceed to solder the wires to the strain gauge

(k)

(12) After soldering we use a Volt Multimeter to measure that there is no contact between wires

If there is none then the specimen is ready for testing

(l)

(13) We now need to measure a 5cm distance and mark it to check and compare the elongation

before and after the tensile testing

(m)

53

Fig 3-9 Specimen-Strain Gauge Process

3 Tensile Test

(1) Enter the computer application that controls the tensile testing machine

(2) Turn on the tensile testing machine main switch

(3) Adjust the hydraulic pump to go back to its original position

(4) Bring the lowering motor down to a distance enough so as to attach the tensile specimen to the

system open the clamps and secure the specimen

(a)

(5) Connect all the necessary wires to the strain indicator equipment

54

(b)

(6) Start the ascending motor and wait for the expansion

(c)

Fig 3-10 Specimen-Tensile Testing Process

4 Start the Test

(1) Enter the software application and enter some variables needed for the experiment in the

specific screen

(2) Go back to the main screen and press the [測試] (measure) button to start the test and auto

recording in the software

(3) After the specimen breaks the mechanical device will automatically stop and ask the user to

enter the total displacement We take out the specimen from the testing machine and adjust the

machinersquos position back to its original position

(4) Save the results information

(5) Record the results from the strain indicator

34 Results

From this experiment we can get the Poissonrsquos Ratio Youngrsquos Modulus and Yield Strength etc and

because of the slippage phenomenon in the clamp at the moment of the test then the Elastic Limit will

display some yield phenomena So omit any undesirable results we just take the Yield portion of the

results as reference

In the process of the experiment the most important part to attend to is the attaching of the strain

gauge because the gaugersquos purpose is to measure the strain developed during the test and this strain

might be very small If the gaugersquos angle change during the test ie is not well attached this will affect

the accuracy of the measurements of Poissonrsquos ratio and Youngrsquos modulus

55

The materials provided by the manufacturer are SUM 23 and SUM 43 steel round bars and these two

types of materials have been through different heat treatment processes so they can be sub-divided

further into untreated material heat-treated material and black surface heat treated material for the two

materials with heat treatment the treatment process and finished are different In the end we only have

the mechanical properties that were calculated after our research of these materials

All of the specifications are identical to those shown in figure 3-6

341 SUM 23

Fig 3-11 SUM 23 Untreated Material

Number 7 10

Hardness(HRB) 74 75

Yield Stress (MPa) 448 440

Tensile Strength (MPa) 544 560

Poissonrsquos Ratio 029 027

Youngrsquos Modulus (GPa) 203 210

Cut-off Area Shrinking () 42 41

Elongation () 1125 1011

Table 3-5 Mechanical Properties of SUM 23 Untreated

56

Stress-Strain Diagram

(a)

(b)

57

Fig 3-12 Stress-Strain Diagrams for (a) 7 Round Bar and (b) 10 Round Bar

Cut-Off Area

(a)

(b)

Fig 3-13 Cut-Off Area of (a) 7 Round Bar and (b) 10 Round Bar

58

SUM 23 Nickel Round Bar

Fig 3-14 SUM 23 Nickel Material

Number 1 2 3 4

Hardness(HRB) 48 50 49 48

Yield Stress (MPa) 370 370 380 400

Tensile Strength (MPa) 455 451 450 450

Poissonrsquos Ratio 028 046 029 026

Youngrsquos Modulus (GPa) 243 303 246 206

Cut-off Area Shrinking () 803 803 726 601

Elongation () 566 65 602 647

Table 3-6 Mechanical Properties of SUM 23 Nickel

59

Stress-Strain Diagram

(a)

60

(b)

(c)

(d)

61

Fig 3-15 Stress-Strain Diagrams for (a) 1 Round Bar (b) 2 Round Bar (c) 3 Round Bar and (d)

4 Round Bar

Cut-Off Area

(a)

(b)

62

(c)

(d)

Fig 3-16 Cut-Off Area of (a) 1 Round Bar (b) 2 Round Bar (c) 3 Round Bar and (d) 4 Round

Bar

63

SUM 23 Black Surface Round Bar

Fig 3-17 SUM 23 Black Surface Material

Number 1 2 3

Hardness(HRB) 51 50 51

Yield Stress (MPa) 378 371 369

Tensile Strength (MPa) 467 465 464

Poissonrsquos Ratio 03 016 04

Youngrsquos Modulus (GPa) 215 266 266

Cut-off Area Shrinking () 986 94 848

Elongation () 748 805 761

Table 3-7 Mechanical Properties of SUM 23 Black Surface Material

64

Stress-Strain Diagram

(a)

(b)

65

(c)

Fig 3-18 Stress-Strain Diagrams for (a) 1 Round Bar 2 Round Bar and (c) 3 Round Bar

Cut-Off Surface

(a)

66

(b)

(c)

Fig 3-19 Cut-Off Surface of (a) 1 Round Bar 2 Round Bar and (c) 3 Round Bar

67

342 SUM 43

Fig 3-20 Untreated SUM 43 Untreated Material

Number 1 5

Hardness(HRB) 76 75

Yield Stress (MPa) 572 594

Tensile Strength (MPa) 743 785

Poissonrsquos Ratio 027 029

Youngrsquos Modulus (GPa) 200 202

Cut-off Area Shrinking () 338 2944

Elongation () 857 894

Table 3-8 Mechanical Properties of SUM 43 Untreated

68

Stress-Strain Diagrams

(a)

(b)

Fig 3-21 Stress-Strain Diagrams for SUM 43 (a) 1 Round Bar and (b) 5 Round Bar

69

Cut-Off Area

(a)

(b)

Fig 3-22 Cut-Off Area of SUM 43 (a) 1 Round Bar and (b) 5 Round Bar

70

SUM 43 Nickel Round Bar

Fig 3-23 SUM 43 Nickel Material

Number 4 5

Hardness(HRB) 51 50

Yield Stress (MPa) 1580 1544

Tensile Strength (MPa) 1639 1625

Poissonrsquos Ratio 03 028

Youngrsquos Modulus (GPa) 194 201

Cut-off Area Shrinking () 1697 137

Elongation () 376 265

Table 3-9 Mechanical Properties of SUM 43 Nickel

71

Stress-Strain Diagrams

(a)

(b)

Fig 3-24 Stress-Strain Diagrams for (a) 4 Round Bar and (b) 5 Round Bar

72

Cut-Off Area

(a)

(b)

Fig 3-25 Cut-Off Area of (a) 4 Round Bar and (b) 5 Round Bar

73

SUM 43 Black Surface Material

Fig 3-26 SUM 43 Black Surface Material

Number 3 5

Hardness(HRB) 56 56

Yield Stress (MPa) 1416 1361

Tensile Strength (MPa) 1591 1402

Poissonrsquos Ratio 029 031

Youngrsquos Modulus (GPa) 200 202

Cut-off Area Shrinking () 139 124

Elongation () 24 24

Table 3-10 Mechanical Properties of SUM 43 Black Surface Material

74

Stress-Strain Diagrams

0 2 4 6 8 10 12 14

-200

0

200

400

600

800

1000

1200

1400

1600

1800

應力 (MPa)

應變()

(a)

0 2 4 6 8 10

-200

0

200

400

600

800

1000

1200

1400

1600

應力

(MPa)

位移 ()

(b)

Fig 3-27 Stress-Strain Diagrams for (a) 3 Round Bar and (b) 5 Round Bar

(Note These curves were formulated using Visual Solutions Inc VisSim Software)

75

Cut-Off Area

(a)

(b)

Fig 3-28 Cut-Off Area of (a) 3 Round Bar and (b) 5 Round Bar

76

The force value (N) was retrieved from the Universal Testing Machine

The Poissonrsquos Ratio (ε) is calculated as

ε =

the values for the Poissonrsquos Ratio are in average around 0297

The Youngrsquos Modulus (E) is calculated as

E =

Where

Stress =

Cross-sectional Area =

where D is the Diameter

The value for D was in average around 1258 mm

The values shown by the computer because there is Slippage phenomena between the Clamp and the

specimen will not be taken into consideration for the elongation strain and Youngrsquos modulus and we will

refer to the values that we have meticulously calculated

77

Chapter 4 AR COATING IN DEPTH

41 Experimentrsquos Purpose and Principles

By means of a vacuum chamber and several other instruments we intend to apply Anti-Reflective

Coating using deposition process to a laser diode and in this way reduce its refraction so as to make it

lose less light in the process of amplification and we can control certain wavelengths we want produced

for certain desired applications in our case we are attempting to re-create a Bose-Einstein Condensate

An optimal BEC apparatus is shown in figure 4-1

Fig 4-1 BEC Apparatus

The main point of this experiment is to build a vacuum chamber system attach all the instrumentation

needed (Vacuum pump deposition meter and voltmeter) and use it to apply AR coating to a laser diode

After we have accomplished the AR coating other team will be in charge of designing the BEC apparatus

and use the results of our research

78

42 Experimentrsquos Equipment

421 Vacuum Chamber

For this research we designed a vacuum chamber whose main body is shown in figure 4-2 Its

dimensions are

Width 240 mm

Length 240 mm

Height 200 mm

Outer Diameter 4 in

Inner Diameter 15 in

Fig 4-2 Vacuum Chamber Main Body

The chamber is made up of 6 pass ways pass way A is the connection with the Laser Deposition

Equipment pass way B is the connection with the Turbo Pump and pass way C is for the connection with

the Deposition Source

A

C

B

79

Pass way C is for the deposition source as mentioned above This is a system where a thermal

resistance is heated by passing a high current through it which heats up a filament boat (made of tungsten)

where the material to be evaporated is place We control the temperature as such that the material will

evaporate and the heat will not cause the filament boat to crack

Because P = Isup2 R (where P is power I is current and R is resistance) to avoid the current to flow

where it is not desired we decided that the material for the Thermocouple shown in figure 4-3 should be

Copper ᴓ 63 mm We choose it that way because Copper has very good heat dissipation characteristics

and the resistance value is low It can reduce the value of the current enough to make the thermocouple to

create heat

Fig 4-3 Thermocouple

To the thermocouple we attach the tungsten filament boat We need to take notice of materials to be

used in this design because when using high current the tungsten filament boar will heat up and so the

material must be able to keep up with the heating potential of tungsten and has a low coefficient of heat

dissipation to avoid the tungsten to fail when heating up and therefore not evaporating Considering all

this we decide to use Stainless Steel

Because this clamp will be assembled inside the chamber after many revisions it was determined it

will have the shape shown in figure 4-4

Fig 4-4 Filament Boat Clamp Design

80

For the tungsten filament boat we bought the product from a distributor The dimensions are

Length 100 mm

Width 10 mm

Height 1 mm

Our thermocouple is 15 in but the pass way C is 4 in so we need to attach a Flange that connects

15in to 4in Because these specifications are quite difficult to achieve by Milling we had to use

electrical wire cutting

For the laser clamping system where the laser that is going to be AR coated will be placed will be

connected to pass way A the assembly is shown in figure 4-5 below

Fig 4-5 Cover Assembly

For this design we used an O-ring instead of a gasket so as to save time The design of the assembly

where the laser will be placed is shown in figure 4-6

Fig 4-6 Upper Cover Inner Assembly

D

E

F

81

Point D is the plate in the assembly where the laser diode will be fixed Because of the easy

processing we decide to use Aluminum and it is screwed to the top cover Point E is the connection for

the Quartz crystal resonator and it is designed in the same as point F in this way the results of the quartz

microbalance system will be more accurate in real time Point F is the final resting place for the laser

diode We use a Thor Labs Base with dimensions of ᴓ 9mm and ᴓ 56mm for two different size laser

diodes It just needs to be plugged in for easy installation

From figure 4-6 we know that the system needs signal system connections and because of the

change in temperature inside the chamber this could affect the functioning of the quartz microbalance so

we also need to install water tubes for cooling This is shown in figure 4-7 below

Fig 4-7 Diagram of Upper Cover Connections

In figure 4-8 we show the Feed through connections and their functions

Fig 4-8 Feed through Diagram

82

1 SQM-160 wire 5 Laser Connection 1 (Vin)

2 SQM-160 (G) 6 Laser Connection 2 (G)

3 K-Type-1 7 Laser Connection 3 (PD)

4 K-Type-2 8 Not In Use

The fully assembled chamber is shown in figure 4-9

Fig 4-9 Fully Assembled Chamber

422 Quartz Crystal Microbalance

For measuring the deposition on our target for coating we used the Inficon SQM-160 RateThickness

Monitor It is an easy to use instrument for measuring many types of thin-film coatings as shown in

figure 4-10

(a) Front Panel (b) Back Panel

Fig 4-10 Inficon SQM-160

83

Table 4-1 shows the technical specifications for this equipment

Number of sensors 2 Standard 4 additional optional

Sensor Frequency Range 40 MHz ~ 60 MHz

Reference Frequency Accuracy 002

Thickness Display Resolution 1 Aring

Thickness Resolution 015 Aring (Std) 0037 Aring (Hi Res)

Density of Stored Films 05-9999 gmcc

Tooling 10-399

Z-Factor 010-1000

Final Thickness 0000-9999k Aring

Measurement Period 15 to 2 sec

Simulation Mode Yes

Frequency Mode Yes

Rate Resolution 011 Arings

Dual Crystal Yes

Etch Mode Yes

Crystal Tooling 10-399

Crystal Fail Min Max 40 to 60 MHz 41 to 61 MHz

Power 100-120 200-240~plusmn10 nominal 20W

Operation Environment 0degC ~ 50degC

0 ~ 80 RH non-condensing

0 ~ 2000 meters

Class 1 Equipment

Pollution Degree 2

Rack Dimensions 885mm x 2127mm x 1969mm

Weight 27 kg

Table 4-1 Inficon SQM-160 RateThickness Monitor Specs

84

To the SQM-160 we need to connect an Oscillator We use the Sigma Instruments Remote Oscillator

Ser No 2 268 as shown in figure 4-11

Fig 4-11 Sigma Instruments Remote Oscillator

The connections diagram is shown in figure 4-12

Fig 4-12 SQM-160 Connections Diagram

85

423 Turbo Pump

For our experiments we used the Pfeiffer TCP 015 Electronic Drive Unit shown below in figure 4-13

Table 4-2 shows the technical specifications for this equipment

(a) Front Panel (b) Back Panel

Fig 4-13 Pfeiffer TCP 015 Electronic Drive

Connection Voltage (100V) 90-112

Mains Frequency 5060 Hz

Start-up Current 22 A

Nominal Frequency 1500 Hz

Rotation Speed 10V = 1500Hz plusmn2

Analog Output Current 10 V = 25 A plusmn 5

Rotation Speed Switchpoint 750 Hz

Works Setting 8 min

Permissible Ambient Temperature 0degC ~ 40degC

Dimensions Front Panel 1285mm x 1063mm

Insertion Length 227mm

Weight 27 Kg

Table 4-2 Pfeiffer TCP 015 Electronic Drive Specs

86

The connections diagram is shown in figure 4-14

Fig 4-14Connections Diagram for Pfeiffer TCP 015

To measure the pressure inside the chamber we use the Granville Phillips 375 Convectron Vacuum

Pressure Controller shown in figure 4-15

(a) Front Panel (b) Back Panel

Fig 4-15 Granville Phillips 375 Convectron

87

Its dimensions are shown in figure 4-16

Fig 4-16 Dimensions of Convectron

Table 4-3 shows the technical specifications for this equipment

Table 4-3 Granville Phillips 375 Convectron Vacuum Pressure Controller Specs

88

424 Multimeter

For our experiment we used the Keithley 2000 Digital Multimeter as shown in figure 4-17

(a) Front Panel (b) Back Panel

Fig 4-17 Keithley Model 2000 6-12-Digit Digital Multimeter

Its technical specifications are shown in table 4-4

Table 4-4 Keithley Model 2000 6-12-Digit Digital Multimeter Specs

89

43 Experiment Procedure

1 Connecting together the equipment and the chamber

(1) We first connect the resonator to the thickness monitor and connect the other side to the

chamber

(2) We now connect the flexible tubes to the turbo pump on one side and to the chamber on the

other

(3) We need to check that tubes are tightly connected to avoid any leaks in the vacuum pumping

process which will not allow us to get to our goal of Torr As shown in figure 4-18

(4) Connect the convectron to the system as shown in figure 4-19

Fig 4-18 checking for leaks using alcohol

Fig 4-19 Convectron attached to System

90

(5) Attach the clamps of the Multimeter to the bottom of the chamber as shown in figure 4-20

(6) Place the Quartz crystal in place

(7) Close tight vacuum chamber

(8) Connect all electrical appliances to power source

Fig 4-20 Multimeter Connections

2 Starting up the System

(1) We turn on all the devices as such Check all systems are ready to function Reset all values

that might be left over from previous tests

(2) Start the thickness monitor and set all values for this experiment In our case we got to testing

the system but not actual coating So we used the simulation mode of the thickness monitor as

shown in figure 4-21

Fig 4-21 Simulation Mode

91

(3) Start the turbo pump Make sure the lid on the vacuum chamber is tightly closed

(4) Start convectron and record initial pressure

(5) Start Multimeter and record initial current

3 Coating Process

(1) If we have the deposition material inside the filament boat the power source for the high

current must be started as well

(2) Record all initial values for thickness current pressure

(3) For an ideal experiment we need a thickness of around 101 nm a pressure of Torr and

a current of 300 A

44 Results

From previous experiments we have shown that we can turn a LED into a laser by means of AR

Coating In figure 4-22 shown below we can compare the actual results of a Diode before and after AR

coating From the blue line we can see that when the diode is at a current of 15mA its light will change

from LED to laser and if we look at the red line its critical current is around 30 to 35 mA

Fig 4-22 AR Coating Comparison for Laser Diodes

This means that the light emitted is not as strong as if the diode had been coated because inside the

chamber there must be some excitation first so the reflectivity of both sides inside the diode must be high

So because of the coating in one of the sides we have opened a door and let the light come out so the

critical current is risen as such and will be higher value than that of before the coating

92

In the following figures we can see the difference between before and after coating in a material The

thickness is around 1016 nm for this material

Fig 4-23 Before Coating

Fig 4-24 After Coating

93

Chapter 5 CONCLUSIONS AND RECOMMENDATIONS

51 Conclusions

For the first part of this independent study taking into consideration the data that came out of our

research and that sent by the provider we can say

1 SUM 23 after heat treatment will unexpectedly develop cracking in the middle of the tensile

testing process and suddenly break

2 Itrsquos possible that in the process of heat treatment to the SUM 23 material the treatment was not

uniform and this will create a pre-loaded moment force on one side that pushes on the other side

of the specimen resulting in material deformation

3 In the process of attaching the strain gauges to the materials it is very easy to make errors due to

poor adhesion or sudden removal in the tensile testing process

For our second part of the independent study the following can be made

1 At the beginning of this independent study we had no idea what Bose-Einstein Condensate was

or what was its purpose After much literature we finally comprehended the basic principles to

put into practice for our research

2 Our systemrsquos basic working principles and equipmentrsquos complexity are a little difficult to grasp

but hopefully we were able to understand enough of it

3 Theoretically from relation between the power and current we can know the advantages and

disadvantages of AR Coating

4 We were able to assemble the system and run test on its functions Even though we were able to

do this there is still much more work left to do with this system

52 Recommendations

For the Tensile Testing the following can be said

1 Ask the provider to check on the process of heat treatment on the SUM 23 material and give

them the information we have gathered through our test so they can correct for the mechanical

properties found if any change is needed

2 To avoid the problem of the inaccuracy of the poor adhesion of strain gauges we can attach

multiple strain gauges to the same one specimen so as to correlate data and improve our results

For the AR Coating the following can be said

1 We need to make sure that there are no physical defects on the main body of the chamber so as to

achieve maximum efficiency in the vacuum process If there was then the vacuum will arrive to

certain point and then start to decrease

2 It would be preferable to add some sort of visual aid that will allow the user to check the inside of

the chamber without actually opening it This will help us determine at what times we should

manipulate the current to better evaporate the substrate

94

REFERENCES

[1] A L Window Strain Gauge Technology Elsevier Applied Science London and New York 2nd

Edition 1992

[2] CC Perry and HR Lissner Strain Gauge Primer McGraw-Hill Book Co Inc New York 1955

[3] James W Dally William F Riley McGraw-Hill 1978

[4] University of Colorado Boulder BEC - What is it and where did the idea come from

httpwwwcoloradoeduphysics2000becwhat_is_ithtml

[5] Ultraslow Light amp Bose-Einstein Condensates Two-way Control with Coherent Light amp Atom

Fields Harvard Hau Lab Dr Lene Vestergaard Hau Optics amp Photonics News 16 1995

[6] The Art of Taming Light Ultra-slow and Stopped Light Harvard Hau Lab Dr Lene

Vestergaard Hau Europhysics News 2004

[7] Nonlinear Optics Shocking Superfluids Harvard Hau Lab Dr Lene Vestergaard Hau Nature

Physics 2007

[8] Model P3 Strain Indicator and Recorder Instruction Manual Vishay Micro-Measurements 2005

[9] Granville-Phillips Series 375 Convectron Vacuum Gauge Controller Instruction Manual Brooks

Automation 2008

[10] Effect of Film Thickness on the Validity of the Sauerbrey Equation for Hydrated Polyelectrolyte

Films Vogt Lin Wu White 2004

[11] Quartz Crystal Microbalance Study of DNA Immobilization and Hybridization for DNA Sensor

Development Chang Zhao 2008

[12] Installation of Strain Gages with SR-4 PrecoatAdhesive Vishay Micro-Measurements 2005

[13] Strain Gauge Measurement ndash A Tutorial National Instruments 1998

[14] Correlation between Vickers Hardness Number and Yield Stress of Cold-Formed Products

Yavuz Tekkaya

[15] httpsenwikipediaorg

Page 17: PC Hinge Materials Testing and AR Laser Diode Coating

17

which increases the electrical resistance through-out From the measured resistance of the strain gauge

the amount of stress may be inferred by using the relations

R=

Where R is the original resistance value is the electrical resistivity lo is the original length of the

conductor and Ao is the original cross sectional area of the conductor If after the application of tension

the change in length is Δl let the length of the specimen be l = l + Δlo and the tension is the same

through-out So

And the resistance is

The Gauge Factor is the ratio of relative change in electrical resistance to the mechanical strain in

other words it is the relative change in length It is defined as

The strain gauge was invented in 1938 by Edward E Simmons and Arthur C Ruge and the most

common type consists of an insulating flexible backing which supports a metallic foil usually made of a

brass-nickel alloy It is attached to the specimen by a suitable adhesive As the object is deformed the foil

also deforms and this causes the electrical resistance to change Then this is usually measured using a

Wheatstone bridge shown below and is related to the strain by the Gauge Factor

Fig2-3 Basic Structure of Strain Gauge

18

Fig 2-4 Strain gauge attached to Wheatstone bridge

22 Hardness Testing Basic Principles

221 Brinell Scale BHN

The Brinell Scale characterizes the indentation hardness of materials through the scale of penetration

of an indenter loaded on a material specimen The typical test uses a 10mm diameter steel ball as indenter

(usually of value equal to BHN450) with a 29kN force For softer materials smaller force is used The

indentation is measured and BHN is calculated using the relation

BHN =

radic

Where F is the applied force usually within the range of 100 250 500 750 1000 1500 2000 2500

and 3000 kgf D is the diameter of indenter usually within the range of 5mm or 10mm plusmn0005 margin

and d is the diameter of indentation usually around 2mm Its units are of Kgmmsup2 but are not normally

written

First proposed by Swedish engineer Johan August Brinell in 1900 it was the first widely used and

standardized hardness test in engineering and metallurgy although the large size of indentation and

possible damage to specimen limits its usefulness

Fig 2-5 Brinell Indentation Fig2-6 Brinell Hardness Tester

19

222 Rockwell Scale HR

The Rockwell scale is a hardness scale based on the indentation hardness of a material The Rockwell

test determines the hardness by measuring the depth of penetration of an indenter under a large load

compared to the penetration made by a preload The indenter is forced into the specimen under a

preliminary load When equilibrium is reached a measuring device follows the movements of the

indenter and responds to changes in depth of penetration of the indenter While the preload is still being

applied additional major load is applied resulting in increased penetration When equilibrium is reached

again the major load is removed but the preload is maintained Removing the major load allows partial

recovery and reduces the depth of penetration The permanent increase in depth of penetration resulting

from the application and removal of the major load is used to calculate the Rockwell number using the

relation

HR = E ndash e

Where E is a constant depending on the form of the indenter 100 units for diamond indenter and 130

units for steel ball indenter e is the permanent increase in depth of penetration due to the major load

measured in units of 0002mm

Fig 2-7 Rockwell Indentation

When testing materials indentation hardness is related linearly to the tensile strength The important

relation permits economically important nondestructive testing of bulk metal deliveries with lightweight

equipment like the Rockwell tester shown below in figure 2-7

Fig 2-8 Rockwell Hardness Tester

20

There are different scales denoted by a single letter that use different loads or different indenters

The result is a dimensionless number denoted as HR X where X will be the letter denoting the scale as

shown below in table 2-1

Table 2-1 Rockwell Hardness Test Scale

Differential depth hardness measurement was first conceived in 1908 by Viennese professor Paul

Ludwik It eliminated the errors associated with the mechanical imperfections of the system such as

backlash and surface imperfections in the specimen Rockwell testing has an advantage over Brinell

testing because the latter was slow itrsquos not useful on fully hardened steel and left too large an impression

to be considered nondestructive

The tester was co-invented by Hugh M Rockwell and Stanley P Rockwell The requirement for this

tester was to quickly determine the effects of heat treatment on steel bearing races

21

223 Vickers Hardness Test HV

This is a type of microindentation hardness test where a diamond indenter of specific geometry is

impressed into the surface of the test specimen using a known applied force ranging from 10 to 1000

grams This type of tests usually has forces of 2N and produce indentations of about 50μm They can be

used to observe changes in hardness on the microscopic scale It is difficult to standardize the

microhardness measurements because it has been found that the microhardness of almost any material is

higher than its macrohardness The values also vary with load and work-hardening effects of materials

The Vickers test is often easier to use than other hardness tests because the required calculations are

independent of the size of the indenter and the indenter can be used for all materials It can be used for all

metals and has one of the widest scales among hardness tests The unit of the Vickers test is denoted as

HV and can be converted to units of Pascal (Pa) but it is not a measurement of pressure The hardness

number is determined by the load over the surface area of the indentation and not the area normal to the

force

A square-based pyramid shaped diamond is use as the indenter It has been established that the ideal

size of a Brinell impression was 38 of the ball diameter As two tangents to the circle at the ends of a

chord 3d8 long intersect at 136plusmn05deg it was decided to use this as the angle of the indenter giving an

angle to the horizontal plane of 22deg on each side The HV number is determined by the ratio FA where F

is the force applied to the diamond in kgf and A is the surface area of the resulting indentation in mmsup2 A

can be determined by the relation

A =

Where A is the surface area of indentation and d is the average length diagonal left by the indenter

This can be approximated as

A =

Then the Vickers Number is

HV =

=

Vickers hardness number is reported as xxxHVyy or xxxHVyyzz (if duration of applied force differs

from 10s to 15s) where xxx are replaced by the hardness number yy is the load in kg and zz indicates

loading time The values are generally independent of test force

The test was developed in 1921 by Robert L Smith and George E Sandland at Vickers Ltd as an

alternative to Brinell method to measure the hardness of materials

22

Fig 2-9 Vickers Indentation Fig 2-10 Vickers Hardness Tester

23 AR Coating

231 Bose-Einstein Condensate

The Bose-Einstein Condensate or BEC is a state of matter of a dilute gas of bosons cooled to

temperatures very near absolute zero around 0K or -27315degC Under such conditions a large fraction of

the bosons occupy the lowest quantum state where the quantum effects become apparent on a

macroscopic scale This gave birth to the Bose-Einstein Statistics which are the rules that govern the

behavior at this state It is one of the two possible ways in which a collection of indistinguishable particles

may occupy a set of available discrete energy states The aggregation of particles in the same state

accounts for the cohesive streaming of laser light and the frictionless creeping of superfluid helium (an

application discussed later) Bose and Einstein recognized that a collection of identical and

indistinguishable particles can be distributed this way This theory applies only to those particles not

limited to single occupancy of the same state particles that do not obey the Pauli Exclusion Principle

restrictions Such particles are the Bosons named after the statistics that correctly describe their behavior

This phenomenon was first predicted by Satyendra Nath Bose around 1924 when he considered how

groups of photons behave He then asked Albert Einstein for help publishing his discoveries to which

Einstein agreed and gave follow up supporting these findings The resulting efforts became the concept of

a Bose gas governed by the Bose-Einstein Statistics described above Einstein demonstrated that cooling

bosonic atoms to a very low temperature would cause them to condense into the lowest accessible

quantum state resulting in a new form of matter

The first gaseous condensate we produced by Eric Cornell and Carl Wieman at the University of

Colorado at Boulder NIST ndash JILA lab sung a gas of rubidium atoms cooled to 170 nK which earned

them the 2001 Nobel Prize in physics together with Wolfgang Ketterle from MIT The transition to BEC

occurs below a critical temperature which for a uniform three dimensional gas consisting of

non-interacting particles with no apparent internal degrees of freedom is given by

23

Tc =

(

)

asymp 33125

Where Tc is the critical temperature n is the particle density m is the mass per boson h is the

reduced Planck constant k is the Boltzmann constant and ζ is the Riemann zeta function

There are two classes of elementary particles defined by whether their quantum spin is a nonnegative

integer or an odd half integer A Bose-Einstein Condensate is shown below in figure 2-11

Fig 2-11 Bose Einstein Condensate at different scales

Bosons are the particles whose quantum spin is a nonnegative integer (s = 0 1 2 etc) Examples of

bosons include fundamental particles (Higgs Boson Photons W and Z Bosons Gluons Gravitons etc)

composite particles (Mesons Hadrons Nuclei and Atoms of Carbon-12 and Helium-4) and

quasi-particles Bosons are considered force carrier particles The Bosons differ from Fermions in that

there is no limit to the number that can occupy the same quantum state This is called the Pauli Exclusion

Principle

The Pauli Exclusion Principle says that no two identical fermions may occupy the same quantum state

simultaneously in other words this means that the total wave function for two identical fermions is

anti-symmetric with respect to exchange of the particles This means that no two electrons in a single

atom can have the same four quantum numbers

Fermion is any particle characterized by Fermi-Dirac Statistics and follows the Pauli Exclusion

Principle described above Quarks Leptons and composite particles (Hadrons Nuclei and Atoms of

Carbon-13 and Helium-3) made of an odd number of these are considered Fermions It can be an

elementary particle such as the electron or a composite particle such as the protons Following the Pauli

24

Exclusion Principle only one fermion can occupy a particular quantum state at any given time If multiple

fermions have the same spatial probability distribution then at least one property of each fermion must be

different Fermions are usually associated with matter because composite fermions are key building

blocks of matter (neutrons and protons)

Fermionsrsquo behavior by the Fermi-Dirac Statistics which describes the energies of single particles in a

system comprising of many identical particles It applies to identical particles with half-odd integer spin

in a system of thermal equilibrium The particles in the system are assumed to have negligible mutual

interaction This allows the many-particle system to be described in terms of single-particle energy states

The result is the Fermi-Dirac distribution of particles over these states and includes the condition that no

two particles can occupy the same state which has considerable effect on the properties of the system

In quantum mechanics the position of an object is uncertain An object has a definite probability of

being at any given point in space This probability is encoded in the wave function mentioned earlier If

one concentrates a large number of identical bosons in a small region then it is possible for their wave

functions to overlap so much that the bosons lose their identity When this happens thatrsquos a Bose-Einstein

Condensate It is only possible at very low temperatures because at high temperatures the individual

bosons have small wave functions and move rapidly which causes them to fly apart

For now applications are still restricted because there are still some setbacks regarding BECs They

are extremely fragile they are being produced in small quantities with just a few million atoms at a time

and finally they can only be made from certain types of atoms Some examples are the atom laser Ketterle

in which a conventional light lase emits a beam of coherent photons this means they are all in phase and

can be concentrated to an extremely small bright spot BECs can slow down light as demonstrated by

Prof Lene Hau PhD in 2001 by the use of a superfluid [7] These manipulations could develop into

new types of telecommunications technology optical storage and quantum computing

BECs are related to super-fluidity and super-conductivity Super-fluidity is the state of matter in

which the behavior is that of a fluid with zero viscosity It was discovered in liquid helium but now it has

applications in astrophysics high-energy physics and theories of quantum gravity

Super-conductivity is a phenomenon of exactly zero electrical resistance and expulsion of magnetic

fields occurring in certain materials when cooled below a characteristic critical temperature A

super-conductor is shown below in figure 2-12

Fig2-12 Super Conductor

25

232 AR Coating Basic Principles

Anti-reflective (AR) coating is a type of optical coating applied to the surface of lenses and other

optical devices (in our case we planned to apply it to a laser diode) to reduce reflection This improves

the efficiency of the system since less light is lost The primary benefit is the elimination of the reflection

itself

When light the medium (glass) it will produce reflection if 100 of the light comes from the air and

enters the glass because therersquos a difference between the index of refraction some of the light will go out

and when the light is coming out of the glass into the air once again because of the difference between

index of refraction some of the light wonrsquot be able to pass through the medium

When the light makes the first trip into the glass there was a loss of about 4 in the reflection and

when the light makes the trip back outside there was another loss of about 4 so when we assume that

100 of the light interacts with the medium actually therersquos just about 92 acting (we neglect the light

absorbed by the glass around 05) To illustrate this idea please refer to figure 2-13

Fig 2-13 Simple Model for Light in Glass Medium

When we apply the AR Coating the light that enters will only have a loss of about 05 and when

making the trip back outside again only 05 of light is loss so we get the result of increasing the light

passing through up to 99 (again neglecting the light absorbed by the glass around 05) To illustrate

this idea please refer to figure 2-14

26

Fig 2-14 Simple Model for Light in Glass Medium after AR Coating

The AR Coating can reduce reflection of incoming light In the case that light hits perpendicular to

the surface of the medium the intensity of the reflection can be calculated using the Reflection

Coefficient

Where n0 and ns are the refractive indices of the first and second media respectively The value of R

varies from 0 (no reflection) to 1 (all light reflected) and is usually quoted as a percentage

Complementary to R is the transmission coefficient or Transmittance If absorption and scattering are

neglected then the value of Transmittance is always 1-R then if a beam of light with intensity I is

incident on the surface a beam of intensity RI is reflected and a beam with intensity TI is transmitted to

the medium

The optimal value is called the Optimal Index of Refraction and is described as

For glass with ns around 15 in air (n0 around 10) then the optimum refractive index will be n1 =

1225

To reduce the refraction in this case we now mean the one that is produced inside the chamber of the

Laser diode the easiest way is to apply a low reflectivity AR coating on the surface of the laser To

measure the appropriate thickness of the coating layer we can use the equations described above By

applying a coat exactly

thickness film we can assure that a certain wavelength is transmitted The

27

reflected waves from the back of the glass medium will be half a wavelength out of phase So they

interfere destructively Because all reflected waves are interfered the maximum amount of light passes

through the coating Please refer to figure 2-15 to illustrate this idea

Fig 2-15 Light Passing through AR Coat and Glass

The most common process to attain this final product is by vacuum deposition For the best coating

results we need to lower the pressure inside the vacuum system to torr

Fig 2-16 Lens without (Top) and With (Bottom) AR Coating

28

233 Laser Diode Basic Principles

A laser diode is a laser whose active medium is a semiconductor similar to that found in

light-emitting diodes (LEDs) Please refer to figure 2-17 The most common type of laser diode is formed

from a p-n junction and powered by injected electric current

Fig 2-17 Laser Diode

Laser diodes are formed by doping a very thin layer on the surface of a crystal wafer The crystal is

doped to produce the n-type region and a p-type region one above the other

By referring to figure 1-2 we can see the basic structure of a working laser When the laser diode has

a current passing through it the light will get excited inside its gain medium and then will start to

resonate this process is called pumping The current exceeds the critical current and then it comes out as

laser light Please refer to figure 1-3 Since we use an external cavity laser we need to apply the AR

coating to the diode and adjust a diffraction grating The laser light comes out the diode and bounces on

the grating making the resonance externally and this becomes the ldquocavityrdquo as shown in figure 2-18

Fig 2-18 Tunable Laser Basic Configuration

29

The most important feature of the external cavity laser is that we can adjust the wavelength easily just

by changing the diffraction gratingrsquos angle and in the end this is the output wavelength of the laser For

different wavelengths there will be different levels of visible light as shown in figure 2-19

Fig 2-19 Light Spectrum

234 Quartz Microbalance System

A Quartz Crystal Microbalance is an instrument that measures a mass per unit area by measuring the

change in frequency of a quartz crystal resonator The resonance is disturbed by the addition or removal

of a small mass due to oxide growthdecay or film deposition (which is the case in our study) at the

surface of the acoustic resonator The QCM can be used under vacuum in gas phase and more recently in

liquid environments It is useful for monitoring the rate of deposition in thin film deposition systems

under vacuum Frequency measurements are easily made with high precision

For our research we used the Sigma Instruments SQM-160 RateThickness Monitor shown in figure

2-20

Fig 2-20 Front and Back Panels of SQM-160

30

The microbalance uses Quartz as the resonator Quartz is one member of the family of crystals that

experience the Piezoelectric Effect

Piezoelectricity is the charge that accumulates in certain solid materials in response to applied

mechanical stress It means electricity resulting from pressure It was discovered in 1880 by Jacques and

Pierre Curie It is understood as the linear electromechanical interaction between the mechanical and the

electrical state in crystalline materials with no inversion symmetry It is a reversible process in that

materials exhibiting direct piezoelectricity also exhibit the reverse This means that the internal generation

of electrical resulting from applied mechanical force and vice versa

By using the piezoelectric effect we can probe as an acoustic resonance by electrical means Applying

alternating current to the quartz crystal induces oscillations This creates a shear wave We can use these

qualities to determine the resonance frequency at high accuracy

The frequency of oscillation of the crystal is partially dependent in the thickness of the crystal During

normal operation all the variables are held constant so a change in thickness correlates directly to a

change in frequency As mass is deposited or etched away the thickness increases or decreases and so the

frequency of oscillation changes accordingly With some simplifying assumptions the frequency change

can be quantified and correlated precisely to the mass change using the Sauerbreyrsquos Equation

Developed by G Sauerbrey in 1959 it is a method for correlating changes in the oscillation

frequency of a piezoelectric crystal with the mass deposited on it It is defined as below

Where f0 is the Resonant frequency Δf is the Frequency change Δm is the mass change A is the

piezoelectrically active area of the crystal q is the Density of quartz (2648 gcmsup3) and μq is the Shear

modulus of quarts(2947x gcmssup2)

Because the film is treated as an extension of thickness Sauerbreyrsquos equation only applies to systems

in which the following 3 conditions are met

Deposited mass must be rigid

Deposited mass must be distributed evenly

The frequency change

lt002

If the change is greater than 2 the Z-match method must be used to determine the change in mass

It is defined as

Where fL is the frequency of the loaded crystal fU is the resonant frequency Nq is the frequency

constant (1668x HzAring) Δm is the mass change A is the piezoelectrically active area of the crystal

31

q is the density of quartz Z is the method constant f is the density of film μq Is the shear modulus of

quarts and μf is the shear modulus of film

The Sauerbrey equation cannot be applied to systems under liquid medium

The crystals are seed crystals plated with gold on both top and bottom for applications A crystal is

shown in figure 2-21 The QCM consists of a thin piezoelectric plate with electrodes evaporated on both

sides Due to the piezoelectric effect AC voltage across the electrodes induces a shear deformation and

vice versa The electromechanical coupling provides a simple way to detect an acoustic resonance by

electrical means

The Z also called Z-factor is a constant value for different materials and it is shown together with the

density of different materials in table 2-2 below

Fig 2-21 QCM Crystals

The Oscillator of the SQM-160 is shown in figure 2-22 and the equivalent circuit for the Resonant

Oscillator is shown in figure 2-23

Fig 2-22 SQM-160 Oscillator

32

Fig 2-23 Oscillator Circuit

33

Table 2-2 Z-Ratios for Different Materials

Table 2-2 Continued

34

Table 2-2 Continued

35

Table 2-2 Continued

36

Table 2-2 Continued

37

Table 2-2 Continued

38

Table 2-2 Continued

235 Vacuum Chamber System

Vacuum Evaporation is the process of depositing thin films of materials onto surfaces The technique

consists of pumping a vacuum chamber to pressures of less than torr and heating a material to

produce a flux of vapor in order to deposit the material onto a surface The material to be vaporized is

typically heated until its vapor pressure is high enough to produce a flux several Angstrom per second by

using an electrically resistive heater or bombardment by a high voltage beam The process was invented

by Henri Nestle in 1886 for food industry

In here the system has been pumped to a vacuum of Torr When a high current is passed

through the filament boat the filament boat is heated over the desired metal evaporation temperature and

so evaporation starts When the evaporation process is finished and the metal cools down crystals

condensate in the surface of the wafer From the weight of the evaporated material the distance between

the filament boat and the wafer we are able to calculate the deposition thickness and we can also use the

mass detector follower like the Quartz crystal resonator microbalance system In the process of

evaporation we usually use a board in between the filament boat and the wafer This is because before we

arrive to the desired evaporation temperature there will be some impurities that will be vaporized in the

controlled environment so we first use a small current and the board in between to get rid of those

impurities and this raises the purity of the deposition material

39

A vacuum evaporation system is shown in figure 2-24

Fig 2-24 Vacuum Evaporation System

Rough Vacuum 760 ~ 1 torr

Medium Vacuum 1 ~ torr

High Vacuum ~ torr

Ultra-High Vacuum Lower than torr

Table 2-3 Classification of Vacuum

For our study we need to use a Turbo Pump A regular turbo pump is shown in figure 2-25

Fig 2-25 Turbo Pump

For our research we used the Pfeiffer TCP 015 Electronic Drive Unit and Granville Phillips 375

Convectron shown below in figure 2-26

40

Fig 2-26 Control and Measurement Equipment

The electronic drive controls the turbo pump and the Convectron measures the pressure inside our

chamber The turbo pump is a type of vacuum pump used to maintain high vacuum Most turbo pumps

are centrifugal When we start the pumping we need to use a mechanical pump so as to decrease the

pressure inside the system from constant atmospheric pressure to torr and then the use dispersion

pump to continue the vacuum until we get to the desired pressure We need to notice though when we

start the dispersion pump we canrsquot turn off the mechanical pump and they both need to run together If

we need to turn off the pumping we first turn off the dispersion pump wait for it to completely stop and

then turn off the mechanical pump

Our completely assembled system is shown in figure 2-27 below

Fig 2-27 Complete System

41

Chapter 3 TENSILE TESTING IN DEPTH

31 Experimentrsquos Purpose and Principles

By means of Universal testing machine and Strain gauges we were able to observe discuss and

analyze the phenomena created when a specimen of certain material is manipulated under an external load

and determine the stress strain and deformation values later we can use the graphing methods of

stress-strain diagram to describe it

The main point of this experiment is that after the tensile specimen is tested use computer analysis

and the actual strain data and after statistical adjustment make the final results report (Tensile testing

experiment is in accordance with ASTM E8)

32 Experimentrsquos Equipment

321 Universal Testing Machine

For the materials testing experiment part of this research we use a Universal Testing Machine as

shown in figure 31 The maximum load it can apply is 100 Ton After the test specimen is secured on the

device with the use of instrumentation the load exerted and the effects of this become apparent on the

specimen and even the smallest of changes can be recorded For our research we used the Chun Yen

Testing Machines Co Ltd 100 Ton Micro Computer Universal Tensile Tester

Fig 31 Universal Testing Machine

42

Table 31 shows the specifications for this machine

Max Capacity 100 Ton

Accuracy plusmn1

Tension (mm) Max Space 1150mm

Grip for Rod 20-70mm

Ram Stroke 250mm

Effective Column Interval 940mm

Crosshead Speed 300mmmin

Testing Speed 0-50mmmin

Volume of Machine 1700times1000times3350mm(LtimesWtimesH)

Volume of Control Panel 1000times800times1500mm(LtimesWtimesH)

Weight 8000kg

Power 3∮220V 20A

Computer AMD K6-2-350

OS Windows XP

Screen 15rdquo CRT

Table 3-1 Chun Yen Testing Machine Specs Table

The connections diagram is shown in figure 3-2

Fig 3-2 Diagram for System Connections

43

When the test specimen is placed when the external force is applied the Load Cell can measure the

size of the applied force and the Encoder measures the expansion rate of change The Local Controller

receives all the information from the 2 units after arranging the results they are displayed in the

computer and they can be afterwards submitted for more complex analysis such as Finite Element

Analysis and we can get the Stress-Strain Diagram

322 Strain Measurement Equipment

The equipment used in our research provides a four-channel measurement that means we can use up

to 4 strain gauges at a time to do our measurements and provides 3 different bridge arrangements as

shown in figure 3-3

(a) (b) (c)

Fig 3-3 Input Connections for Strain Indicator

Figure 3-3 (a) is the Quarter Bridge (b) is the Half Bridge and (c) is the Full Bridge and Transducers

For our study we used the Quarter Bridge and use the Strain Gauge values to decide the position of the

connecting wires The Strain indicator is shown in figure 3-4

Fig 3-4 Vishay Micro-Measurements Model P3 Strain Indicator and Recorder

44

Input Connections Tool Free eccentric lever release

4-channel input

Wire diameter16-28AWG

Bridge Configurations Quarter- Half- and Full Bridge

Bridge Impedance 60-2000Ω

Display 128 64 pixel FSTN positive gray LCD

Data Conversion AD Converter filter

Measurement Range Resolution Strain Range plusmn155mVV

Resolution plusmn00005mVV

Measurement Accuracy plusmn01 of reading plusmn3 counts

Gage Factor Control 0500-9900

Balance Control Software either manual or automatic

Bridge Excitation 15VDC nominal

Communication Interface USB Cable Included

Data Storage Removable Media Card

Shunt Calibration Across bridge completion resistors controlled

by software When Gage Factor=200

120Ω350Ω1000Ω

Analog Output Value 0 to 25V max

Ranges plusmn320 microε plusmn3200 microε plusmn32000 microε

Error 05 output voltage +5mV

Max Error 14 output voltage + 20mV

Update rate 480 samplessec

Output Load 2000Ω

Power Battery Two Alkaline D cells

Battery life 400 hours typ

USB 5V 100mA

Operational Environment Temperature 0-50

Humidity Up to 90 Non-condensing

Case Aluminum Alloy

Size and Weight 228times152times152(mm) 20(kg)

Table 3-2 Vishay Micro-Measurements Model P3 Strain Indicator and Recorder Specs

45

323 Strain Gauge

The strain gaugersquos main basic principle is to use a resistancersquos characteristics to measure the strain

The inside connections of the strain indicator are shown in figure 3-5

Fig 3-5 Inner Connections

As shown above this is a quarter-bridge connection We connect equal-length 3 wires to the 2

connections allowed by the strain gauge wire 1 and 3 can be used to cancel out the effects of temperature

to the resistance and because of the addition of wires 1 and 3 wire 2 can directly measure the experiment

results from the strain gauge and therefore the strain developed with no influence of temperature

If there were no two measuring leads then the relations will be

R 4 =R g +2R L

Where Rg is the Strain Gauge Value and RL is the wire resistance then

4

4

R

R=

Lg

g

RR

R

2

=

gL

gg

RR

RR

21

amp

4

4

R

R=

g

g

R

R(1- L)

Where L is the Signal Loss Factor and so

L =gL

gL

RR

RR

21

2

g

L

R

2R if

g

L

R

2Rltlt1

46

(Actual Value R g =120R L =08g

L

R

2Ris always much smaller than 1)

R 4 =R g +2R LR 2 =R 3 =rR gR 1 =R g 32 RR =0

V 0 =V 2)1( r

r

(

4

4

R

R-

1

1

R

R)

The first term describes loss attenuation effects second term describes loss of balancing capabilities

effects

V 0 =V 2)1( r

r

[

)2

(Lg

g

RR

R

+

T

Lg

g

RR

R

)

2( + T

Lg

L

RR

R

)

2

2( -(

g

g

R

R) T ]

The first term describes loss attenuation effects and loss of balancing capabilities effects the second

third and fourth terms describe the temperature effects on the wire

For the three-wire method we have

L =gL

gL

RR

RR

1

g

L

R

R if

g

L

R

Rltlt1

V 0 =V 2)1( r

r

[

)(Lg

g

RR

R

+

T

Lg

g

RR

R

)( + T

Lg

L

RR

R

)

2( -

T

Lg

g

RR

R

)( - T

Lg

L

RR

R

)

2( ]

V 0 = V2)1( r

r

)(

Lg

g

RR

R

In the last four terms inside parenthesis we can see the effects of temperature being cancelled out and the

effect on first term is not great so this is the reason why in our research we use three wires

47

324 Specimen Measurements

The tensile specimens used in this research are compliant of ASTM E8 Tensile parameters as shown

in figure 3-6

Fig 3-6 Tensile Specimen

Diameter

D(mm)

Gauge

Length

G(mm)

Smallest

Arc

Radius

R(mm)

Shortest

Area

A(mm)

Total

Length

L(mm)

Clamping

Area

Length

B(mm)

Clamping

Area

Diameter

C(mm)

Bar 125 02 625 01 gt10 gt75 ~ 145 ~ 35 20

Table 3-3 Specifications for Round Bar

33 Experiment Procedure

1 Attaching the Strain Gauge to the Tensile Specimen

(1) Prepare 1 ASTM E8 compliant tensile specimen round bar as shown in figure 3-7

(2) Prepare Strain Gauge as those described in table 3-4

(3) Prepare other consumables and adhesive agent such as epoxy adhesive or

cyanoacrylate adhesive as shown in figure 3-8

48

Fig 3-7 Actual Tensile Specimen

Fig 3-8 Other Materials Used (Such as Alcohol gauze transparent tape adhesive)

Gage Type

EA-06-120LZ-120E

Resistance in ohms at 24∘C

1200plusmn03

Gage Factor at 24∘C

2075plusmn05

Transverse Sensitivity at 24∘C

(+07plusmn02)

Table 3-4 Specifications for Strain Gauge

2 Attaching Strain Gauge

As shown in following figures we shall explain the attachment of the strain gauge

(1) Use sand paper and a rasp to clean thoroughly the surface where the strain gauge will be

attached to

49

(a)

(2) Use alcohol to wash the surface where the strain gauge will be attached and use gauze to rub

it off

(b)

(3) Find a clean surface and clean it with alcohol and gauze

(c)

(4) Place the strain gauge in the clean surface Use a piece of transparent tape on top of the strain

gauge after securely placed rip it off the surface carefully

50

(d)

(5) Use a piece of white paper to mark the place where the strain gauge will be attached and in

this way we can make sure that the strain gauge will be placed as horizontally and vertically

correct as possible

(e)

(6) In the place where we had our mark place the strain gauge

(f)

(7) Carefully lift one side of the tape and apply some of the adhesive agent to both the strain

gauge and specimenrsquos surface

(g)

51

(8) We need to make sure that the gauge and the specimen will be firmly attached so we gently

apply pressure with our thumb

(h)

(9) After the adhesive is fully dry we can carefully rip off the tape

(i)

(10) We need to do the whole process twice one for the horizontally placed strain gauge and one

for the vertically placed strain gauge

52

(j)

(11) We now proceed to solder the wires to the strain gauge

(k)

(12) After soldering we use a Volt Multimeter to measure that there is no contact between wires

If there is none then the specimen is ready for testing

(l)

(13) We now need to measure a 5cm distance and mark it to check and compare the elongation

before and after the tensile testing

(m)

53

Fig 3-9 Specimen-Strain Gauge Process

3 Tensile Test

(1) Enter the computer application that controls the tensile testing machine

(2) Turn on the tensile testing machine main switch

(3) Adjust the hydraulic pump to go back to its original position

(4) Bring the lowering motor down to a distance enough so as to attach the tensile specimen to the

system open the clamps and secure the specimen

(a)

(5) Connect all the necessary wires to the strain indicator equipment

54

(b)

(6) Start the ascending motor and wait for the expansion

(c)

Fig 3-10 Specimen-Tensile Testing Process

4 Start the Test

(1) Enter the software application and enter some variables needed for the experiment in the

specific screen

(2) Go back to the main screen and press the [測試] (measure) button to start the test and auto

recording in the software

(3) After the specimen breaks the mechanical device will automatically stop and ask the user to

enter the total displacement We take out the specimen from the testing machine and adjust the

machinersquos position back to its original position

(4) Save the results information

(5) Record the results from the strain indicator

34 Results

From this experiment we can get the Poissonrsquos Ratio Youngrsquos Modulus and Yield Strength etc and

because of the slippage phenomenon in the clamp at the moment of the test then the Elastic Limit will

display some yield phenomena So omit any undesirable results we just take the Yield portion of the

results as reference

In the process of the experiment the most important part to attend to is the attaching of the strain

gauge because the gaugersquos purpose is to measure the strain developed during the test and this strain

might be very small If the gaugersquos angle change during the test ie is not well attached this will affect

the accuracy of the measurements of Poissonrsquos ratio and Youngrsquos modulus

55

The materials provided by the manufacturer are SUM 23 and SUM 43 steel round bars and these two

types of materials have been through different heat treatment processes so they can be sub-divided

further into untreated material heat-treated material and black surface heat treated material for the two

materials with heat treatment the treatment process and finished are different In the end we only have

the mechanical properties that were calculated after our research of these materials

All of the specifications are identical to those shown in figure 3-6

341 SUM 23

Fig 3-11 SUM 23 Untreated Material

Number 7 10

Hardness(HRB) 74 75

Yield Stress (MPa) 448 440

Tensile Strength (MPa) 544 560

Poissonrsquos Ratio 029 027

Youngrsquos Modulus (GPa) 203 210

Cut-off Area Shrinking () 42 41

Elongation () 1125 1011

Table 3-5 Mechanical Properties of SUM 23 Untreated

56

Stress-Strain Diagram

(a)

(b)

57

Fig 3-12 Stress-Strain Diagrams for (a) 7 Round Bar and (b) 10 Round Bar

Cut-Off Area

(a)

(b)

Fig 3-13 Cut-Off Area of (a) 7 Round Bar and (b) 10 Round Bar

58

SUM 23 Nickel Round Bar

Fig 3-14 SUM 23 Nickel Material

Number 1 2 3 4

Hardness(HRB) 48 50 49 48

Yield Stress (MPa) 370 370 380 400

Tensile Strength (MPa) 455 451 450 450

Poissonrsquos Ratio 028 046 029 026

Youngrsquos Modulus (GPa) 243 303 246 206

Cut-off Area Shrinking () 803 803 726 601

Elongation () 566 65 602 647

Table 3-6 Mechanical Properties of SUM 23 Nickel

59

Stress-Strain Diagram

(a)

60

(b)

(c)

(d)

61

Fig 3-15 Stress-Strain Diagrams for (a) 1 Round Bar (b) 2 Round Bar (c) 3 Round Bar and (d)

4 Round Bar

Cut-Off Area

(a)

(b)

62

(c)

(d)

Fig 3-16 Cut-Off Area of (a) 1 Round Bar (b) 2 Round Bar (c) 3 Round Bar and (d) 4 Round

Bar

63

SUM 23 Black Surface Round Bar

Fig 3-17 SUM 23 Black Surface Material

Number 1 2 3

Hardness(HRB) 51 50 51

Yield Stress (MPa) 378 371 369

Tensile Strength (MPa) 467 465 464

Poissonrsquos Ratio 03 016 04

Youngrsquos Modulus (GPa) 215 266 266

Cut-off Area Shrinking () 986 94 848

Elongation () 748 805 761

Table 3-7 Mechanical Properties of SUM 23 Black Surface Material

64

Stress-Strain Diagram

(a)

(b)

65

(c)

Fig 3-18 Stress-Strain Diagrams for (a) 1 Round Bar 2 Round Bar and (c) 3 Round Bar

Cut-Off Surface

(a)

66

(b)

(c)

Fig 3-19 Cut-Off Surface of (a) 1 Round Bar 2 Round Bar and (c) 3 Round Bar

67

342 SUM 43

Fig 3-20 Untreated SUM 43 Untreated Material

Number 1 5

Hardness(HRB) 76 75

Yield Stress (MPa) 572 594

Tensile Strength (MPa) 743 785

Poissonrsquos Ratio 027 029

Youngrsquos Modulus (GPa) 200 202

Cut-off Area Shrinking () 338 2944

Elongation () 857 894

Table 3-8 Mechanical Properties of SUM 43 Untreated

68

Stress-Strain Diagrams

(a)

(b)

Fig 3-21 Stress-Strain Diagrams for SUM 43 (a) 1 Round Bar and (b) 5 Round Bar

69

Cut-Off Area

(a)

(b)

Fig 3-22 Cut-Off Area of SUM 43 (a) 1 Round Bar and (b) 5 Round Bar

70

SUM 43 Nickel Round Bar

Fig 3-23 SUM 43 Nickel Material

Number 4 5

Hardness(HRB) 51 50

Yield Stress (MPa) 1580 1544

Tensile Strength (MPa) 1639 1625

Poissonrsquos Ratio 03 028

Youngrsquos Modulus (GPa) 194 201

Cut-off Area Shrinking () 1697 137

Elongation () 376 265

Table 3-9 Mechanical Properties of SUM 43 Nickel

71

Stress-Strain Diagrams

(a)

(b)

Fig 3-24 Stress-Strain Diagrams for (a) 4 Round Bar and (b) 5 Round Bar

72

Cut-Off Area

(a)

(b)

Fig 3-25 Cut-Off Area of (a) 4 Round Bar and (b) 5 Round Bar

73

SUM 43 Black Surface Material

Fig 3-26 SUM 43 Black Surface Material

Number 3 5

Hardness(HRB) 56 56

Yield Stress (MPa) 1416 1361

Tensile Strength (MPa) 1591 1402

Poissonrsquos Ratio 029 031

Youngrsquos Modulus (GPa) 200 202

Cut-off Area Shrinking () 139 124

Elongation () 24 24

Table 3-10 Mechanical Properties of SUM 43 Black Surface Material

74

Stress-Strain Diagrams

0 2 4 6 8 10 12 14

-200

0

200

400

600

800

1000

1200

1400

1600

1800

應力 (MPa)

應變()

(a)

0 2 4 6 8 10

-200

0

200

400

600

800

1000

1200

1400

1600

應力

(MPa)

位移 ()

(b)

Fig 3-27 Stress-Strain Diagrams for (a) 3 Round Bar and (b) 5 Round Bar

(Note These curves were formulated using Visual Solutions Inc VisSim Software)

75

Cut-Off Area

(a)

(b)

Fig 3-28 Cut-Off Area of (a) 3 Round Bar and (b) 5 Round Bar

76

The force value (N) was retrieved from the Universal Testing Machine

The Poissonrsquos Ratio (ε) is calculated as

ε =

the values for the Poissonrsquos Ratio are in average around 0297

The Youngrsquos Modulus (E) is calculated as

E =

Where

Stress =

Cross-sectional Area =

where D is the Diameter

The value for D was in average around 1258 mm

The values shown by the computer because there is Slippage phenomena between the Clamp and the

specimen will not be taken into consideration for the elongation strain and Youngrsquos modulus and we will

refer to the values that we have meticulously calculated

77

Chapter 4 AR COATING IN DEPTH

41 Experimentrsquos Purpose and Principles

By means of a vacuum chamber and several other instruments we intend to apply Anti-Reflective

Coating using deposition process to a laser diode and in this way reduce its refraction so as to make it

lose less light in the process of amplification and we can control certain wavelengths we want produced

for certain desired applications in our case we are attempting to re-create a Bose-Einstein Condensate

An optimal BEC apparatus is shown in figure 4-1

Fig 4-1 BEC Apparatus

The main point of this experiment is to build a vacuum chamber system attach all the instrumentation

needed (Vacuum pump deposition meter and voltmeter) and use it to apply AR coating to a laser diode

After we have accomplished the AR coating other team will be in charge of designing the BEC apparatus

and use the results of our research

78

42 Experimentrsquos Equipment

421 Vacuum Chamber

For this research we designed a vacuum chamber whose main body is shown in figure 4-2 Its

dimensions are

Width 240 mm

Length 240 mm

Height 200 mm

Outer Diameter 4 in

Inner Diameter 15 in

Fig 4-2 Vacuum Chamber Main Body

The chamber is made up of 6 pass ways pass way A is the connection with the Laser Deposition

Equipment pass way B is the connection with the Turbo Pump and pass way C is for the connection with

the Deposition Source

A

C

B

79

Pass way C is for the deposition source as mentioned above This is a system where a thermal

resistance is heated by passing a high current through it which heats up a filament boat (made of tungsten)

where the material to be evaporated is place We control the temperature as such that the material will

evaporate and the heat will not cause the filament boat to crack

Because P = Isup2 R (where P is power I is current and R is resistance) to avoid the current to flow

where it is not desired we decided that the material for the Thermocouple shown in figure 4-3 should be

Copper ᴓ 63 mm We choose it that way because Copper has very good heat dissipation characteristics

and the resistance value is low It can reduce the value of the current enough to make the thermocouple to

create heat

Fig 4-3 Thermocouple

To the thermocouple we attach the tungsten filament boat We need to take notice of materials to be

used in this design because when using high current the tungsten filament boar will heat up and so the

material must be able to keep up with the heating potential of tungsten and has a low coefficient of heat

dissipation to avoid the tungsten to fail when heating up and therefore not evaporating Considering all

this we decide to use Stainless Steel

Because this clamp will be assembled inside the chamber after many revisions it was determined it

will have the shape shown in figure 4-4

Fig 4-4 Filament Boat Clamp Design

80

For the tungsten filament boat we bought the product from a distributor The dimensions are

Length 100 mm

Width 10 mm

Height 1 mm

Our thermocouple is 15 in but the pass way C is 4 in so we need to attach a Flange that connects

15in to 4in Because these specifications are quite difficult to achieve by Milling we had to use

electrical wire cutting

For the laser clamping system where the laser that is going to be AR coated will be placed will be

connected to pass way A the assembly is shown in figure 4-5 below

Fig 4-5 Cover Assembly

For this design we used an O-ring instead of a gasket so as to save time The design of the assembly

where the laser will be placed is shown in figure 4-6

Fig 4-6 Upper Cover Inner Assembly

D

E

F

81

Point D is the plate in the assembly where the laser diode will be fixed Because of the easy

processing we decide to use Aluminum and it is screwed to the top cover Point E is the connection for

the Quartz crystal resonator and it is designed in the same as point F in this way the results of the quartz

microbalance system will be more accurate in real time Point F is the final resting place for the laser

diode We use a Thor Labs Base with dimensions of ᴓ 9mm and ᴓ 56mm for two different size laser

diodes It just needs to be plugged in for easy installation

From figure 4-6 we know that the system needs signal system connections and because of the

change in temperature inside the chamber this could affect the functioning of the quartz microbalance so

we also need to install water tubes for cooling This is shown in figure 4-7 below

Fig 4-7 Diagram of Upper Cover Connections

In figure 4-8 we show the Feed through connections and their functions

Fig 4-8 Feed through Diagram

82

1 SQM-160 wire 5 Laser Connection 1 (Vin)

2 SQM-160 (G) 6 Laser Connection 2 (G)

3 K-Type-1 7 Laser Connection 3 (PD)

4 K-Type-2 8 Not In Use

The fully assembled chamber is shown in figure 4-9

Fig 4-9 Fully Assembled Chamber

422 Quartz Crystal Microbalance

For measuring the deposition on our target for coating we used the Inficon SQM-160 RateThickness

Monitor It is an easy to use instrument for measuring many types of thin-film coatings as shown in

figure 4-10

(a) Front Panel (b) Back Panel

Fig 4-10 Inficon SQM-160

83

Table 4-1 shows the technical specifications for this equipment

Number of sensors 2 Standard 4 additional optional

Sensor Frequency Range 40 MHz ~ 60 MHz

Reference Frequency Accuracy 002

Thickness Display Resolution 1 Aring

Thickness Resolution 015 Aring (Std) 0037 Aring (Hi Res)

Density of Stored Films 05-9999 gmcc

Tooling 10-399

Z-Factor 010-1000

Final Thickness 0000-9999k Aring

Measurement Period 15 to 2 sec

Simulation Mode Yes

Frequency Mode Yes

Rate Resolution 011 Arings

Dual Crystal Yes

Etch Mode Yes

Crystal Tooling 10-399

Crystal Fail Min Max 40 to 60 MHz 41 to 61 MHz

Power 100-120 200-240~plusmn10 nominal 20W

Operation Environment 0degC ~ 50degC

0 ~ 80 RH non-condensing

0 ~ 2000 meters

Class 1 Equipment

Pollution Degree 2

Rack Dimensions 885mm x 2127mm x 1969mm

Weight 27 kg

Table 4-1 Inficon SQM-160 RateThickness Monitor Specs

84

To the SQM-160 we need to connect an Oscillator We use the Sigma Instruments Remote Oscillator

Ser No 2 268 as shown in figure 4-11

Fig 4-11 Sigma Instruments Remote Oscillator

The connections diagram is shown in figure 4-12

Fig 4-12 SQM-160 Connections Diagram

85

423 Turbo Pump

For our experiments we used the Pfeiffer TCP 015 Electronic Drive Unit shown below in figure 4-13

Table 4-2 shows the technical specifications for this equipment

(a) Front Panel (b) Back Panel

Fig 4-13 Pfeiffer TCP 015 Electronic Drive

Connection Voltage (100V) 90-112

Mains Frequency 5060 Hz

Start-up Current 22 A

Nominal Frequency 1500 Hz

Rotation Speed 10V = 1500Hz plusmn2

Analog Output Current 10 V = 25 A plusmn 5

Rotation Speed Switchpoint 750 Hz

Works Setting 8 min

Permissible Ambient Temperature 0degC ~ 40degC

Dimensions Front Panel 1285mm x 1063mm

Insertion Length 227mm

Weight 27 Kg

Table 4-2 Pfeiffer TCP 015 Electronic Drive Specs

86

The connections diagram is shown in figure 4-14

Fig 4-14Connections Diagram for Pfeiffer TCP 015

To measure the pressure inside the chamber we use the Granville Phillips 375 Convectron Vacuum

Pressure Controller shown in figure 4-15

(a) Front Panel (b) Back Panel

Fig 4-15 Granville Phillips 375 Convectron

87

Its dimensions are shown in figure 4-16

Fig 4-16 Dimensions of Convectron

Table 4-3 shows the technical specifications for this equipment

Table 4-3 Granville Phillips 375 Convectron Vacuum Pressure Controller Specs

88

424 Multimeter

For our experiment we used the Keithley 2000 Digital Multimeter as shown in figure 4-17

(a) Front Panel (b) Back Panel

Fig 4-17 Keithley Model 2000 6-12-Digit Digital Multimeter

Its technical specifications are shown in table 4-4

Table 4-4 Keithley Model 2000 6-12-Digit Digital Multimeter Specs

89

43 Experiment Procedure

1 Connecting together the equipment and the chamber

(1) We first connect the resonator to the thickness monitor and connect the other side to the

chamber

(2) We now connect the flexible tubes to the turbo pump on one side and to the chamber on the

other

(3) We need to check that tubes are tightly connected to avoid any leaks in the vacuum pumping

process which will not allow us to get to our goal of Torr As shown in figure 4-18

(4) Connect the convectron to the system as shown in figure 4-19

Fig 4-18 checking for leaks using alcohol

Fig 4-19 Convectron attached to System

90

(5) Attach the clamps of the Multimeter to the bottom of the chamber as shown in figure 4-20

(6) Place the Quartz crystal in place

(7) Close tight vacuum chamber

(8) Connect all electrical appliances to power source

Fig 4-20 Multimeter Connections

2 Starting up the System

(1) We turn on all the devices as such Check all systems are ready to function Reset all values

that might be left over from previous tests

(2) Start the thickness monitor and set all values for this experiment In our case we got to testing

the system but not actual coating So we used the simulation mode of the thickness monitor as

shown in figure 4-21

Fig 4-21 Simulation Mode

91

(3) Start the turbo pump Make sure the lid on the vacuum chamber is tightly closed

(4) Start convectron and record initial pressure

(5) Start Multimeter and record initial current

3 Coating Process

(1) If we have the deposition material inside the filament boat the power source for the high

current must be started as well

(2) Record all initial values for thickness current pressure

(3) For an ideal experiment we need a thickness of around 101 nm a pressure of Torr and

a current of 300 A

44 Results

From previous experiments we have shown that we can turn a LED into a laser by means of AR

Coating In figure 4-22 shown below we can compare the actual results of a Diode before and after AR

coating From the blue line we can see that when the diode is at a current of 15mA its light will change

from LED to laser and if we look at the red line its critical current is around 30 to 35 mA

Fig 4-22 AR Coating Comparison for Laser Diodes

This means that the light emitted is not as strong as if the diode had been coated because inside the

chamber there must be some excitation first so the reflectivity of both sides inside the diode must be high

So because of the coating in one of the sides we have opened a door and let the light come out so the

critical current is risen as such and will be higher value than that of before the coating

92

In the following figures we can see the difference between before and after coating in a material The

thickness is around 1016 nm for this material

Fig 4-23 Before Coating

Fig 4-24 After Coating

93

Chapter 5 CONCLUSIONS AND RECOMMENDATIONS

51 Conclusions

For the first part of this independent study taking into consideration the data that came out of our

research and that sent by the provider we can say

1 SUM 23 after heat treatment will unexpectedly develop cracking in the middle of the tensile

testing process and suddenly break

2 Itrsquos possible that in the process of heat treatment to the SUM 23 material the treatment was not

uniform and this will create a pre-loaded moment force on one side that pushes on the other side

of the specimen resulting in material deformation

3 In the process of attaching the strain gauges to the materials it is very easy to make errors due to

poor adhesion or sudden removal in the tensile testing process

For our second part of the independent study the following can be made

1 At the beginning of this independent study we had no idea what Bose-Einstein Condensate was

or what was its purpose After much literature we finally comprehended the basic principles to

put into practice for our research

2 Our systemrsquos basic working principles and equipmentrsquos complexity are a little difficult to grasp

but hopefully we were able to understand enough of it

3 Theoretically from relation between the power and current we can know the advantages and

disadvantages of AR Coating

4 We were able to assemble the system and run test on its functions Even though we were able to

do this there is still much more work left to do with this system

52 Recommendations

For the Tensile Testing the following can be said

1 Ask the provider to check on the process of heat treatment on the SUM 23 material and give

them the information we have gathered through our test so they can correct for the mechanical

properties found if any change is needed

2 To avoid the problem of the inaccuracy of the poor adhesion of strain gauges we can attach

multiple strain gauges to the same one specimen so as to correlate data and improve our results

For the AR Coating the following can be said

1 We need to make sure that there are no physical defects on the main body of the chamber so as to

achieve maximum efficiency in the vacuum process If there was then the vacuum will arrive to

certain point and then start to decrease

2 It would be preferable to add some sort of visual aid that will allow the user to check the inside of

the chamber without actually opening it This will help us determine at what times we should

manipulate the current to better evaporate the substrate

94

REFERENCES

[1] A L Window Strain Gauge Technology Elsevier Applied Science London and New York 2nd

Edition 1992

[2] CC Perry and HR Lissner Strain Gauge Primer McGraw-Hill Book Co Inc New York 1955

[3] James W Dally William F Riley McGraw-Hill 1978

[4] University of Colorado Boulder BEC - What is it and where did the idea come from

httpwwwcoloradoeduphysics2000becwhat_is_ithtml

[5] Ultraslow Light amp Bose-Einstein Condensates Two-way Control with Coherent Light amp Atom

Fields Harvard Hau Lab Dr Lene Vestergaard Hau Optics amp Photonics News 16 1995

[6] The Art of Taming Light Ultra-slow and Stopped Light Harvard Hau Lab Dr Lene

Vestergaard Hau Europhysics News 2004

[7] Nonlinear Optics Shocking Superfluids Harvard Hau Lab Dr Lene Vestergaard Hau Nature

Physics 2007

[8] Model P3 Strain Indicator and Recorder Instruction Manual Vishay Micro-Measurements 2005

[9] Granville-Phillips Series 375 Convectron Vacuum Gauge Controller Instruction Manual Brooks

Automation 2008

[10] Effect of Film Thickness on the Validity of the Sauerbrey Equation for Hydrated Polyelectrolyte

Films Vogt Lin Wu White 2004

[11] Quartz Crystal Microbalance Study of DNA Immobilization and Hybridization for DNA Sensor

Development Chang Zhao 2008

[12] Installation of Strain Gages with SR-4 PrecoatAdhesive Vishay Micro-Measurements 2005

[13] Strain Gauge Measurement ndash A Tutorial National Instruments 1998

[14] Correlation between Vickers Hardness Number and Yield Stress of Cold-Formed Products

Yavuz Tekkaya

[15] httpsenwikipediaorg

Page 18: PC Hinge Materials Testing and AR Laser Diode Coating

18

Fig 2-4 Strain gauge attached to Wheatstone bridge

22 Hardness Testing Basic Principles

221 Brinell Scale BHN

The Brinell Scale characterizes the indentation hardness of materials through the scale of penetration

of an indenter loaded on a material specimen The typical test uses a 10mm diameter steel ball as indenter

(usually of value equal to BHN450) with a 29kN force For softer materials smaller force is used The

indentation is measured and BHN is calculated using the relation

BHN =

radic

Where F is the applied force usually within the range of 100 250 500 750 1000 1500 2000 2500

and 3000 kgf D is the diameter of indenter usually within the range of 5mm or 10mm plusmn0005 margin

and d is the diameter of indentation usually around 2mm Its units are of Kgmmsup2 but are not normally

written

First proposed by Swedish engineer Johan August Brinell in 1900 it was the first widely used and

standardized hardness test in engineering and metallurgy although the large size of indentation and

possible damage to specimen limits its usefulness

Fig 2-5 Brinell Indentation Fig2-6 Brinell Hardness Tester

19

222 Rockwell Scale HR

The Rockwell scale is a hardness scale based on the indentation hardness of a material The Rockwell

test determines the hardness by measuring the depth of penetration of an indenter under a large load

compared to the penetration made by a preload The indenter is forced into the specimen under a

preliminary load When equilibrium is reached a measuring device follows the movements of the

indenter and responds to changes in depth of penetration of the indenter While the preload is still being

applied additional major load is applied resulting in increased penetration When equilibrium is reached

again the major load is removed but the preload is maintained Removing the major load allows partial

recovery and reduces the depth of penetration The permanent increase in depth of penetration resulting

from the application and removal of the major load is used to calculate the Rockwell number using the

relation

HR = E ndash e

Where E is a constant depending on the form of the indenter 100 units for diamond indenter and 130

units for steel ball indenter e is the permanent increase in depth of penetration due to the major load

measured in units of 0002mm

Fig 2-7 Rockwell Indentation

When testing materials indentation hardness is related linearly to the tensile strength The important

relation permits economically important nondestructive testing of bulk metal deliveries with lightweight

equipment like the Rockwell tester shown below in figure 2-7

Fig 2-8 Rockwell Hardness Tester

20

There are different scales denoted by a single letter that use different loads or different indenters

The result is a dimensionless number denoted as HR X where X will be the letter denoting the scale as

shown below in table 2-1

Table 2-1 Rockwell Hardness Test Scale

Differential depth hardness measurement was first conceived in 1908 by Viennese professor Paul

Ludwik It eliminated the errors associated with the mechanical imperfections of the system such as

backlash and surface imperfections in the specimen Rockwell testing has an advantage over Brinell

testing because the latter was slow itrsquos not useful on fully hardened steel and left too large an impression

to be considered nondestructive

The tester was co-invented by Hugh M Rockwell and Stanley P Rockwell The requirement for this

tester was to quickly determine the effects of heat treatment on steel bearing races

21

223 Vickers Hardness Test HV

This is a type of microindentation hardness test where a diamond indenter of specific geometry is

impressed into the surface of the test specimen using a known applied force ranging from 10 to 1000

grams This type of tests usually has forces of 2N and produce indentations of about 50μm They can be

used to observe changes in hardness on the microscopic scale It is difficult to standardize the

microhardness measurements because it has been found that the microhardness of almost any material is

higher than its macrohardness The values also vary with load and work-hardening effects of materials

The Vickers test is often easier to use than other hardness tests because the required calculations are

independent of the size of the indenter and the indenter can be used for all materials It can be used for all

metals and has one of the widest scales among hardness tests The unit of the Vickers test is denoted as

HV and can be converted to units of Pascal (Pa) but it is not a measurement of pressure The hardness

number is determined by the load over the surface area of the indentation and not the area normal to the

force

A square-based pyramid shaped diamond is use as the indenter It has been established that the ideal

size of a Brinell impression was 38 of the ball diameter As two tangents to the circle at the ends of a

chord 3d8 long intersect at 136plusmn05deg it was decided to use this as the angle of the indenter giving an

angle to the horizontal plane of 22deg on each side The HV number is determined by the ratio FA where F

is the force applied to the diamond in kgf and A is the surface area of the resulting indentation in mmsup2 A

can be determined by the relation

A =

Where A is the surface area of indentation and d is the average length diagonal left by the indenter

This can be approximated as

A =

Then the Vickers Number is

HV =

=

Vickers hardness number is reported as xxxHVyy or xxxHVyyzz (if duration of applied force differs

from 10s to 15s) where xxx are replaced by the hardness number yy is the load in kg and zz indicates

loading time The values are generally independent of test force

The test was developed in 1921 by Robert L Smith and George E Sandland at Vickers Ltd as an

alternative to Brinell method to measure the hardness of materials

22

Fig 2-9 Vickers Indentation Fig 2-10 Vickers Hardness Tester

23 AR Coating

231 Bose-Einstein Condensate

The Bose-Einstein Condensate or BEC is a state of matter of a dilute gas of bosons cooled to

temperatures very near absolute zero around 0K or -27315degC Under such conditions a large fraction of

the bosons occupy the lowest quantum state where the quantum effects become apparent on a

macroscopic scale This gave birth to the Bose-Einstein Statistics which are the rules that govern the

behavior at this state It is one of the two possible ways in which a collection of indistinguishable particles

may occupy a set of available discrete energy states The aggregation of particles in the same state

accounts for the cohesive streaming of laser light and the frictionless creeping of superfluid helium (an

application discussed later) Bose and Einstein recognized that a collection of identical and

indistinguishable particles can be distributed this way This theory applies only to those particles not

limited to single occupancy of the same state particles that do not obey the Pauli Exclusion Principle

restrictions Such particles are the Bosons named after the statistics that correctly describe their behavior

This phenomenon was first predicted by Satyendra Nath Bose around 1924 when he considered how

groups of photons behave He then asked Albert Einstein for help publishing his discoveries to which

Einstein agreed and gave follow up supporting these findings The resulting efforts became the concept of

a Bose gas governed by the Bose-Einstein Statistics described above Einstein demonstrated that cooling

bosonic atoms to a very low temperature would cause them to condense into the lowest accessible

quantum state resulting in a new form of matter

The first gaseous condensate we produced by Eric Cornell and Carl Wieman at the University of

Colorado at Boulder NIST ndash JILA lab sung a gas of rubidium atoms cooled to 170 nK which earned

them the 2001 Nobel Prize in physics together with Wolfgang Ketterle from MIT The transition to BEC

occurs below a critical temperature which for a uniform three dimensional gas consisting of

non-interacting particles with no apparent internal degrees of freedom is given by

23

Tc =

(

)

asymp 33125

Where Tc is the critical temperature n is the particle density m is the mass per boson h is the

reduced Planck constant k is the Boltzmann constant and ζ is the Riemann zeta function

There are two classes of elementary particles defined by whether their quantum spin is a nonnegative

integer or an odd half integer A Bose-Einstein Condensate is shown below in figure 2-11

Fig 2-11 Bose Einstein Condensate at different scales

Bosons are the particles whose quantum spin is a nonnegative integer (s = 0 1 2 etc) Examples of

bosons include fundamental particles (Higgs Boson Photons W and Z Bosons Gluons Gravitons etc)

composite particles (Mesons Hadrons Nuclei and Atoms of Carbon-12 and Helium-4) and

quasi-particles Bosons are considered force carrier particles The Bosons differ from Fermions in that

there is no limit to the number that can occupy the same quantum state This is called the Pauli Exclusion

Principle

The Pauli Exclusion Principle says that no two identical fermions may occupy the same quantum state

simultaneously in other words this means that the total wave function for two identical fermions is

anti-symmetric with respect to exchange of the particles This means that no two electrons in a single

atom can have the same four quantum numbers

Fermion is any particle characterized by Fermi-Dirac Statistics and follows the Pauli Exclusion

Principle described above Quarks Leptons and composite particles (Hadrons Nuclei and Atoms of

Carbon-13 and Helium-3) made of an odd number of these are considered Fermions It can be an

elementary particle such as the electron or a composite particle such as the protons Following the Pauli

24

Exclusion Principle only one fermion can occupy a particular quantum state at any given time If multiple

fermions have the same spatial probability distribution then at least one property of each fermion must be

different Fermions are usually associated with matter because composite fermions are key building

blocks of matter (neutrons and protons)

Fermionsrsquo behavior by the Fermi-Dirac Statistics which describes the energies of single particles in a

system comprising of many identical particles It applies to identical particles with half-odd integer spin

in a system of thermal equilibrium The particles in the system are assumed to have negligible mutual

interaction This allows the many-particle system to be described in terms of single-particle energy states

The result is the Fermi-Dirac distribution of particles over these states and includes the condition that no

two particles can occupy the same state which has considerable effect on the properties of the system

In quantum mechanics the position of an object is uncertain An object has a definite probability of

being at any given point in space This probability is encoded in the wave function mentioned earlier If

one concentrates a large number of identical bosons in a small region then it is possible for their wave

functions to overlap so much that the bosons lose their identity When this happens thatrsquos a Bose-Einstein

Condensate It is only possible at very low temperatures because at high temperatures the individual

bosons have small wave functions and move rapidly which causes them to fly apart

For now applications are still restricted because there are still some setbacks regarding BECs They

are extremely fragile they are being produced in small quantities with just a few million atoms at a time

and finally they can only be made from certain types of atoms Some examples are the atom laser Ketterle

in which a conventional light lase emits a beam of coherent photons this means they are all in phase and

can be concentrated to an extremely small bright spot BECs can slow down light as demonstrated by

Prof Lene Hau PhD in 2001 by the use of a superfluid [7] These manipulations could develop into

new types of telecommunications technology optical storage and quantum computing

BECs are related to super-fluidity and super-conductivity Super-fluidity is the state of matter in

which the behavior is that of a fluid with zero viscosity It was discovered in liquid helium but now it has

applications in astrophysics high-energy physics and theories of quantum gravity

Super-conductivity is a phenomenon of exactly zero electrical resistance and expulsion of magnetic

fields occurring in certain materials when cooled below a characteristic critical temperature A

super-conductor is shown below in figure 2-12

Fig2-12 Super Conductor

25

232 AR Coating Basic Principles

Anti-reflective (AR) coating is a type of optical coating applied to the surface of lenses and other

optical devices (in our case we planned to apply it to a laser diode) to reduce reflection This improves

the efficiency of the system since less light is lost The primary benefit is the elimination of the reflection

itself

When light the medium (glass) it will produce reflection if 100 of the light comes from the air and

enters the glass because therersquos a difference between the index of refraction some of the light will go out

and when the light is coming out of the glass into the air once again because of the difference between

index of refraction some of the light wonrsquot be able to pass through the medium

When the light makes the first trip into the glass there was a loss of about 4 in the reflection and

when the light makes the trip back outside there was another loss of about 4 so when we assume that

100 of the light interacts with the medium actually therersquos just about 92 acting (we neglect the light

absorbed by the glass around 05) To illustrate this idea please refer to figure 2-13

Fig 2-13 Simple Model for Light in Glass Medium

When we apply the AR Coating the light that enters will only have a loss of about 05 and when

making the trip back outside again only 05 of light is loss so we get the result of increasing the light

passing through up to 99 (again neglecting the light absorbed by the glass around 05) To illustrate

this idea please refer to figure 2-14

26

Fig 2-14 Simple Model for Light in Glass Medium after AR Coating

The AR Coating can reduce reflection of incoming light In the case that light hits perpendicular to

the surface of the medium the intensity of the reflection can be calculated using the Reflection

Coefficient

Where n0 and ns are the refractive indices of the first and second media respectively The value of R

varies from 0 (no reflection) to 1 (all light reflected) and is usually quoted as a percentage

Complementary to R is the transmission coefficient or Transmittance If absorption and scattering are

neglected then the value of Transmittance is always 1-R then if a beam of light with intensity I is

incident on the surface a beam of intensity RI is reflected and a beam with intensity TI is transmitted to

the medium

The optimal value is called the Optimal Index of Refraction and is described as

For glass with ns around 15 in air (n0 around 10) then the optimum refractive index will be n1 =

1225

To reduce the refraction in this case we now mean the one that is produced inside the chamber of the

Laser diode the easiest way is to apply a low reflectivity AR coating on the surface of the laser To

measure the appropriate thickness of the coating layer we can use the equations described above By

applying a coat exactly

thickness film we can assure that a certain wavelength is transmitted The

27

reflected waves from the back of the glass medium will be half a wavelength out of phase So they

interfere destructively Because all reflected waves are interfered the maximum amount of light passes

through the coating Please refer to figure 2-15 to illustrate this idea

Fig 2-15 Light Passing through AR Coat and Glass

The most common process to attain this final product is by vacuum deposition For the best coating

results we need to lower the pressure inside the vacuum system to torr

Fig 2-16 Lens without (Top) and With (Bottom) AR Coating

28

233 Laser Diode Basic Principles

A laser diode is a laser whose active medium is a semiconductor similar to that found in

light-emitting diodes (LEDs) Please refer to figure 2-17 The most common type of laser diode is formed

from a p-n junction and powered by injected electric current

Fig 2-17 Laser Diode

Laser diodes are formed by doping a very thin layer on the surface of a crystal wafer The crystal is

doped to produce the n-type region and a p-type region one above the other

By referring to figure 1-2 we can see the basic structure of a working laser When the laser diode has

a current passing through it the light will get excited inside its gain medium and then will start to

resonate this process is called pumping The current exceeds the critical current and then it comes out as

laser light Please refer to figure 1-3 Since we use an external cavity laser we need to apply the AR

coating to the diode and adjust a diffraction grating The laser light comes out the diode and bounces on

the grating making the resonance externally and this becomes the ldquocavityrdquo as shown in figure 2-18

Fig 2-18 Tunable Laser Basic Configuration

29

The most important feature of the external cavity laser is that we can adjust the wavelength easily just

by changing the diffraction gratingrsquos angle and in the end this is the output wavelength of the laser For

different wavelengths there will be different levels of visible light as shown in figure 2-19

Fig 2-19 Light Spectrum

234 Quartz Microbalance System

A Quartz Crystal Microbalance is an instrument that measures a mass per unit area by measuring the

change in frequency of a quartz crystal resonator The resonance is disturbed by the addition or removal

of a small mass due to oxide growthdecay or film deposition (which is the case in our study) at the

surface of the acoustic resonator The QCM can be used under vacuum in gas phase and more recently in

liquid environments It is useful for monitoring the rate of deposition in thin film deposition systems

under vacuum Frequency measurements are easily made with high precision

For our research we used the Sigma Instruments SQM-160 RateThickness Monitor shown in figure

2-20

Fig 2-20 Front and Back Panels of SQM-160

30

The microbalance uses Quartz as the resonator Quartz is one member of the family of crystals that

experience the Piezoelectric Effect

Piezoelectricity is the charge that accumulates in certain solid materials in response to applied

mechanical stress It means electricity resulting from pressure It was discovered in 1880 by Jacques and

Pierre Curie It is understood as the linear electromechanical interaction between the mechanical and the

electrical state in crystalline materials with no inversion symmetry It is a reversible process in that

materials exhibiting direct piezoelectricity also exhibit the reverse This means that the internal generation

of electrical resulting from applied mechanical force and vice versa

By using the piezoelectric effect we can probe as an acoustic resonance by electrical means Applying

alternating current to the quartz crystal induces oscillations This creates a shear wave We can use these

qualities to determine the resonance frequency at high accuracy

The frequency of oscillation of the crystal is partially dependent in the thickness of the crystal During

normal operation all the variables are held constant so a change in thickness correlates directly to a

change in frequency As mass is deposited or etched away the thickness increases or decreases and so the

frequency of oscillation changes accordingly With some simplifying assumptions the frequency change

can be quantified and correlated precisely to the mass change using the Sauerbreyrsquos Equation

Developed by G Sauerbrey in 1959 it is a method for correlating changes in the oscillation

frequency of a piezoelectric crystal with the mass deposited on it It is defined as below

Where f0 is the Resonant frequency Δf is the Frequency change Δm is the mass change A is the

piezoelectrically active area of the crystal q is the Density of quartz (2648 gcmsup3) and μq is the Shear

modulus of quarts(2947x gcmssup2)

Because the film is treated as an extension of thickness Sauerbreyrsquos equation only applies to systems

in which the following 3 conditions are met

Deposited mass must be rigid

Deposited mass must be distributed evenly

The frequency change

lt002

If the change is greater than 2 the Z-match method must be used to determine the change in mass

It is defined as

Where fL is the frequency of the loaded crystal fU is the resonant frequency Nq is the frequency

constant (1668x HzAring) Δm is the mass change A is the piezoelectrically active area of the crystal

31

q is the density of quartz Z is the method constant f is the density of film μq Is the shear modulus of

quarts and μf is the shear modulus of film

The Sauerbrey equation cannot be applied to systems under liquid medium

The crystals are seed crystals plated with gold on both top and bottom for applications A crystal is

shown in figure 2-21 The QCM consists of a thin piezoelectric plate with electrodes evaporated on both

sides Due to the piezoelectric effect AC voltage across the electrodes induces a shear deformation and

vice versa The electromechanical coupling provides a simple way to detect an acoustic resonance by

electrical means

The Z also called Z-factor is a constant value for different materials and it is shown together with the

density of different materials in table 2-2 below

Fig 2-21 QCM Crystals

The Oscillator of the SQM-160 is shown in figure 2-22 and the equivalent circuit for the Resonant

Oscillator is shown in figure 2-23

Fig 2-22 SQM-160 Oscillator

32

Fig 2-23 Oscillator Circuit

33

Table 2-2 Z-Ratios for Different Materials

Table 2-2 Continued

34

Table 2-2 Continued

35

Table 2-2 Continued

36

Table 2-2 Continued

37

Table 2-2 Continued

38

Table 2-2 Continued

235 Vacuum Chamber System

Vacuum Evaporation is the process of depositing thin films of materials onto surfaces The technique

consists of pumping a vacuum chamber to pressures of less than torr and heating a material to

produce a flux of vapor in order to deposit the material onto a surface The material to be vaporized is

typically heated until its vapor pressure is high enough to produce a flux several Angstrom per second by

using an electrically resistive heater or bombardment by a high voltage beam The process was invented

by Henri Nestle in 1886 for food industry

In here the system has been pumped to a vacuum of Torr When a high current is passed

through the filament boat the filament boat is heated over the desired metal evaporation temperature and

so evaporation starts When the evaporation process is finished and the metal cools down crystals

condensate in the surface of the wafer From the weight of the evaporated material the distance between

the filament boat and the wafer we are able to calculate the deposition thickness and we can also use the

mass detector follower like the Quartz crystal resonator microbalance system In the process of

evaporation we usually use a board in between the filament boat and the wafer This is because before we

arrive to the desired evaporation temperature there will be some impurities that will be vaporized in the

controlled environment so we first use a small current and the board in between to get rid of those

impurities and this raises the purity of the deposition material

39

A vacuum evaporation system is shown in figure 2-24

Fig 2-24 Vacuum Evaporation System

Rough Vacuum 760 ~ 1 torr

Medium Vacuum 1 ~ torr

High Vacuum ~ torr

Ultra-High Vacuum Lower than torr

Table 2-3 Classification of Vacuum

For our study we need to use a Turbo Pump A regular turbo pump is shown in figure 2-25

Fig 2-25 Turbo Pump

For our research we used the Pfeiffer TCP 015 Electronic Drive Unit and Granville Phillips 375

Convectron shown below in figure 2-26

40

Fig 2-26 Control and Measurement Equipment

The electronic drive controls the turbo pump and the Convectron measures the pressure inside our

chamber The turbo pump is a type of vacuum pump used to maintain high vacuum Most turbo pumps

are centrifugal When we start the pumping we need to use a mechanical pump so as to decrease the

pressure inside the system from constant atmospheric pressure to torr and then the use dispersion

pump to continue the vacuum until we get to the desired pressure We need to notice though when we

start the dispersion pump we canrsquot turn off the mechanical pump and they both need to run together If

we need to turn off the pumping we first turn off the dispersion pump wait for it to completely stop and

then turn off the mechanical pump

Our completely assembled system is shown in figure 2-27 below

Fig 2-27 Complete System

41

Chapter 3 TENSILE TESTING IN DEPTH

31 Experimentrsquos Purpose and Principles

By means of Universal testing machine and Strain gauges we were able to observe discuss and

analyze the phenomena created when a specimen of certain material is manipulated under an external load

and determine the stress strain and deformation values later we can use the graphing methods of

stress-strain diagram to describe it

The main point of this experiment is that after the tensile specimen is tested use computer analysis

and the actual strain data and after statistical adjustment make the final results report (Tensile testing

experiment is in accordance with ASTM E8)

32 Experimentrsquos Equipment

321 Universal Testing Machine

For the materials testing experiment part of this research we use a Universal Testing Machine as

shown in figure 31 The maximum load it can apply is 100 Ton After the test specimen is secured on the

device with the use of instrumentation the load exerted and the effects of this become apparent on the

specimen and even the smallest of changes can be recorded For our research we used the Chun Yen

Testing Machines Co Ltd 100 Ton Micro Computer Universal Tensile Tester

Fig 31 Universal Testing Machine

42

Table 31 shows the specifications for this machine

Max Capacity 100 Ton

Accuracy plusmn1

Tension (mm) Max Space 1150mm

Grip for Rod 20-70mm

Ram Stroke 250mm

Effective Column Interval 940mm

Crosshead Speed 300mmmin

Testing Speed 0-50mmmin

Volume of Machine 1700times1000times3350mm(LtimesWtimesH)

Volume of Control Panel 1000times800times1500mm(LtimesWtimesH)

Weight 8000kg

Power 3∮220V 20A

Computer AMD K6-2-350

OS Windows XP

Screen 15rdquo CRT

Table 3-1 Chun Yen Testing Machine Specs Table

The connections diagram is shown in figure 3-2

Fig 3-2 Diagram for System Connections

43

When the test specimen is placed when the external force is applied the Load Cell can measure the

size of the applied force and the Encoder measures the expansion rate of change The Local Controller

receives all the information from the 2 units after arranging the results they are displayed in the

computer and they can be afterwards submitted for more complex analysis such as Finite Element

Analysis and we can get the Stress-Strain Diagram

322 Strain Measurement Equipment

The equipment used in our research provides a four-channel measurement that means we can use up

to 4 strain gauges at a time to do our measurements and provides 3 different bridge arrangements as

shown in figure 3-3

(a) (b) (c)

Fig 3-3 Input Connections for Strain Indicator

Figure 3-3 (a) is the Quarter Bridge (b) is the Half Bridge and (c) is the Full Bridge and Transducers

For our study we used the Quarter Bridge and use the Strain Gauge values to decide the position of the

connecting wires The Strain indicator is shown in figure 3-4

Fig 3-4 Vishay Micro-Measurements Model P3 Strain Indicator and Recorder

44

Input Connections Tool Free eccentric lever release

4-channel input

Wire diameter16-28AWG

Bridge Configurations Quarter- Half- and Full Bridge

Bridge Impedance 60-2000Ω

Display 128 64 pixel FSTN positive gray LCD

Data Conversion AD Converter filter

Measurement Range Resolution Strain Range plusmn155mVV

Resolution plusmn00005mVV

Measurement Accuracy plusmn01 of reading plusmn3 counts

Gage Factor Control 0500-9900

Balance Control Software either manual or automatic

Bridge Excitation 15VDC nominal

Communication Interface USB Cable Included

Data Storage Removable Media Card

Shunt Calibration Across bridge completion resistors controlled

by software When Gage Factor=200

120Ω350Ω1000Ω

Analog Output Value 0 to 25V max

Ranges plusmn320 microε plusmn3200 microε plusmn32000 microε

Error 05 output voltage +5mV

Max Error 14 output voltage + 20mV

Update rate 480 samplessec

Output Load 2000Ω

Power Battery Two Alkaline D cells

Battery life 400 hours typ

USB 5V 100mA

Operational Environment Temperature 0-50

Humidity Up to 90 Non-condensing

Case Aluminum Alloy

Size and Weight 228times152times152(mm) 20(kg)

Table 3-2 Vishay Micro-Measurements Model P3 Strain Indicator and Recorder Specs

45

323 Strain Gauge

The strain gaugersquos main basic principle is to use a resistancersquos characteristics to measure the strain

The inside connections of the strain indicator are shown in figure 3-5

Fig 3-5 Inner Connections

As shown above this is a quarter-bridge connection We connect equal-length 3 wires to the 2

connections allowed by the strain gauge wire 1 and 3 can be used to cancel out the effects of temperature

to the resistance and because of the addition of wires 1 and 3 wire 2 can directly measure the experiment

results from the strain gauge and therefore the strain developed with no influence of temperature

If there were no two measuring leads then the relations will be

R 4 =R g +2R L

Where Rg is the Strain Gauge Value and RL is the wire resistance then

4

4

R

R=

Lg

g

RR

R

2

=

gL

gg

RR

RR

21

amp

4

4

R

R=

g

g

R

R(1- L)

Where L is the Signal Loss Factor and so

L =gL

gL

RR

RR

21

2

g

L

R

2R if

g

L

R

2Rltlt1

46

(Actual Value R g =120R L =08g

L

R

2Ris always much smaller than 1)

R 4 =R g +2R LR 2 =R 3 =rR gR 1 =R g 32 RR =0

V 0 =V 2)1( r

r

(

4

4

R

R-

1

1

R

R)

The first term describes loss attenuation effects second term describes loss of balancing capabilities

effects

V 0 =V 2)1( r

r

[

)2

(Lg

g

RR

R

+

T

Lg

g

RR

R

)

2( + T

Lg

L

RR

R

)

2

2( -(

g

g

R

R) T ]

The first term describes loss attenuation effects and loss of balancing capabilities effects the second

third and fourth terms describe the temperature effects on the wire

For the three-wire method we have

L =gL

gL

RR

RR

1

g

L

R

R if

g

L

R

Rltlt1

V 0 =V 2)1( r

r

[

)(Lg

g

RR

R

+

T

Lg

g

RR

R

)( + T

Lg

L

RR

R

)

2( -

T

Lg

g

RR

R

)( - T

Lg

L

RR

R

)

2( ]

V 0 = V2)1( r

r

)(

Lg

g

RR

R

In the last four terms inside parenthesis we can see the effects of temperature being cancelled out and the

effect on first term is not great so this is the reason why in our research we use three wires

47

324 Specimen Measurements

The tensile specimens used in this research are compliant of ASTM E8 Tensile parameters as shown

in figure 3-6

Fig 3-6 Tensile Specimen

Diameter

D(mm)

Gauge

Length

G(mm)

Smallest

Arc

Radius

R(mm)

Shortest

Area

A(mm)

Total

Length

L(mm)

Clamping

Area

Length

B(mm)

Clamping

Area

Diameter

C(mm)

Bar 125 02 625 01 gt10 gt75 ~ 145 ~ 35 20

Table 3-3 Specifications for Round Bar

33 Experiment Procedure

1 Attaching the Strain Gauge to the Tensile Specimen

(1) Prepare 1 ASTM E8 compliant tensile specimen round bar as shown in figure 3-7

(2) Prepare Strain Gauge as those described in table 3-4

(3) Prepare other consumables and adhesive agent such as epoxy adhesive or

cyanoacrylate adhesive as shown in figure 3-8

48

Fig 3-7 Actual Tensile Specimen

Fig 3-8 Other Materials Used (Such as Alcohol gauze transparent tape adhesive)

Gage Type

EA-06-120LZ-120E

Resistance in ohms at 24∘C

1200plusmn03

Gage Factor at 24∘C

2075plusmn05

Transverse Sensitivity at 24∘C

(+07plusmn02)

Table 3-4 Specifications for Strain Gauge

2 Attaching Strain Gauge

As shown in following figures we shall explain the attachment of the strain gauge

(1) Use sand paper and a rasp to clean thoroughly the surface where the strain gauge will be

attached to

49

(a)

(2) Use alcohol to wash the surface where the strain gauge will be attached and use gauze to rub

it off

(b)

(3) Find a clean surface and clean it with alcohol and gauze

(c)

(4) Place the strain gauge in the clean surface Use a piece of transparent tape on top of the strain

gauge after securely placed rip it off the surface carefully

50

(d)

(5) Use a piece of white paper to mark the place where the strain gauge will be attached and in

this way we can make sure that the strain gauge will be placed as horizontally and vertically

correct as possible

(e)

(6) In the place where we had our mark place the strain gauge

(f)

(7) Carefully lift one side of the tape and apply some of the adhesive agent to both the strain

gauge and specimenrsquos surface

(g)

51

(8) We need to make sure that the gauge and the specimen will be firmly attached so we gently

apply pressure with our thumb

(h)

(9) After the adhesive is fully dry we can carefully rip off the tape

(i)

(10) We need to do the whole process twice one for the horizontally placed strain gauge and one

for the vertically placed strain gauge

52

(j)

(11) We now proceed to solder the wires to the strain gauge

(k)

(12) After soldering we use a Volt Multimeter to measure that there is no contact between wires

If there is none then the specimen is ready for testing

(l)

(13) We now need to measure a 5cm distance and mark it to check and compare the elongation

before and after the tensile testing

(m)

53

Fig 3-9 Specimen-Strain Gauge Process

3 Tensile Test

(1) Enter the computer application that controls the tensile testing machine

(2) Turn on the tensile testing machine main switch

(3) Adjust the hydraulic pump to go back to its original position

(4) Bring the lowering motor down to a distance enough so as to attach the tensile specimen to the

system open the clamps and secure the specimen

(a)

(5) Connect all the necessary wires to the strain indicator equipment

54

(b)

(6) Start the ascending motor and wait for the expansion

(c)

Fig 3-10 Specimen-Tensile Testing Process

4 Start the Test

(1) Enter the software application and enter some variables needed for the experiment in the

specific screen

(2) Go back to the main screen and press the [測試] (measure) button to start the test and auto

recording in the software

(3) After the specimen breaks the mechanical device will automatically stop and ask the user to

enter the total displacement We take out the specimen from the testing machine and adjust the

machinersquos position back to its original position

(4) Save the results information

(5) Record the results from the strain indicator

34 Results

From this experiment we can get the Poissonrsquos Ratio Youngrsquos Modulus and Yield Strength etc and

because of the slippage phenomenon in the clamp at the moment of the test then the Elastic Limit will

display some yield phenomena So omit any undesirable results we just take the Yield portion of the

results as reference

In the process of the experiment the most important part to attend to is the attaching of the strain

gauge because the gaugersquos purpose is to measure the strain developed during the test and this strain

might be very small If the gaugersquos angle change during the test ie is not well attached this will affect

the accuracy of the measurements of Poissonrsquos ratio and Youngrsquos modulus

55

The materials provided by the manufacturer are SUM 23 and SUM 43 steel round bars and these two

types of materials have been through different heat treatment processes so they can be sub-divided

further into untreated material heat-treated material and black surface heat treated material for the two

materials with heat treatment the treatment process and finished are different In the end we only have

the mechanical properties that were calculated after our research of these materials

All of the specifications are identical to those shown in figure 3-6

341 SUM 23

Fig 3-11 SUM 23 Untreated Material

Number 7 10

Hardness(HRB) 74 75

Yield Stress (MPa) 448 440

Tensile Strength (MPa) 544 560

Poissonrsquos Ratio 029 027

Youngrsquos Modulus (GPa) 203 210

Cut-off Area Shrinking () 42 41

Elongation () 1125 1011

Table 3-5 Mechanical Properties of SUM 23 Untreated

56

Stress-Strain Diagram

(a)

(b)

57

Fig 3-12 Stress-Strain Diagrams for (a) 7 Round Bar and (b) 10 Round Bar

Cut-Off Area

(a)

(b)

Fig 3-13 Cut-Off Area of (a) 7 Round Bar and (b) 10 Round Bar

58

SUM 23 Nickel Round Bar

Fig 3-14 SUM 23 Nickel Material

Number 1 2 3 4

Hardness(HRB) 48 50 49 48

Yield Stress (MPa) 370 370 380 400

Tensile Strength (MPa) 455 451 450 450

Poissonrsquos Ratio 028 046 029 026

Youngrsquos Modulus (GPa) 243 303 246 206

Cut-off Area Shrinking () 803 803 726 601

Elongation () 566 65 602 647

Table 3-6 Mechanical Properties of SUM 23 Nickel

59

Stress-Strain Diagram

(a)

60

(b)

(c)

(d)

61

Fig 3-15 Stress-Strain Diagrams for (a) 1 Round Bar (b) 2 Round Bar (c) 3 Round Bar and (d)

4 Round Bar

Cut-Off Area

(a)

(b)

62

(c)

(d)

Fig 3-16 Cut-Off Area of (a) 1 Round Bar (b) 2 Round Bar (c) 3 Round Bar and (d) 4 Round

Bar

63

SUM 23 Black Surface Round Bar

Fig 3-17 SUM 23 Black Surface Material

Number 1 2 3

Hardness(HRB) 51 50 51

Yield Stress (MPa) 378 371 369

Tensile Strength (MPa) 467 465 464

Poissonrsquos Ratio 03 016 04

Youngrsquos Modulus (GPa) 215 266 266

Cut-off Area Shrinking () 986 94 848

Elongation () 748 805 761

Table 3-7 Mechanical Properties of SUM 23 Black Surface Material

64

Stress-Strain Diagram

(a)

(b)

65

(c)

Fig 3-18 Stress-Strain Diagrams for (a) 1 Round Bar 2 Round Bar and (c) 3 Round Bar

Cut-Off Surface

(a)

66

(b)

(c)

Fig 3-19 Cut-Off Surface of (a) 1 Round Bar 2 Round Bar and (c) 3 Round Bar

67

342 SUM 43

Fig 3-20 Untreated SUM 43 Untreated Material

Number 1 5

Hardness(HRB) 76 75

Yield Stress (MPa) 572 594

Tensile Strength (MPa) 743 785

Poissonrsquos Ratio 027 029

Youngrsquos Modulus (GPa) 200 202

Cut-off Area Shrinking () 338 2944

Elongation () 857 894

Table 3-8 Mechanical Properties of SUM 43 Untreated

68

Stress-Strain Diagrams

(a)

(b)

Fig 3-21 Stress-Strain Diagrams for SUM 43 (a) 1 Round Bar and (b) 5 Round Bar

69

Cut-Off Area

(a)

(b)

Fig 3-22 Cut-Off Area of SUM 43 (a) 1 Round Bar and (b) 5 Round Bar

70

SUM 43 Nickel Round Bar

Fig 3-23 SUM 43 Nickel Material

Number 4 5

Hardness(HRB) 51 50

Yield Stress (MPa) 1580 1544

Tensile Strength (MPa) 1639 1625

Poissonrsquos Ratio 03 028

Youngrsquos Modulus (GPa) 194 201

Cut-off Area Shrinking () 1697 137

Elongation () 376 265

Table 3-9 Mechanical Properties of SUM 43 Nickel

71

Stress-Strain Diagrams

(a)

(b)

Fig 3-24 Stress-Strain Diagrams for (a) 4 Round Bar and (b) 5 Round Bar

72

Cut-Off Area

(a)

(b)

Fig 3-25 Cut-Off Area of (a) 4 Round Bar and (b) 5 Round Bar

73

SUM 43 Black Surface Material

Fig 3-26 SUM 43 Black Surface Material

Number 3 5

Hardness(HRB) 56 56

Yield Stress (MPa) 1416 1361

Tensile Strength (MPa) 1591 1402

Poissonrsquos Ratio 029 031

Youngrsquos Modulus (GPa) 200 202

Cut-off Area Shrinking () 139 124

Elongation () 24 24

Table 3-10 Mechanical Properties of SUM 43 Black Surface Material

74

Stress-Strain Diagrams

0 2 4 6 8 10 12 14

-200

0

200

400

600

800

1000

1200

1400

1600

1800

應力 (MPa)

應變()

(a)

0 2 4 6 8 10

-200

0

200

400

600

800

1000

1200

1400

1600

應力

(MPa)

位移 ()

(b)

Fig 3-27 Stress-Strain Diagrams for (a) 3 Round Bar and (b) 5 Round Bar

(Note These curves were formulated using Visual Solutions Inc VisSim Software)

75

Cut-Off Area

(a)

(b)

Fig 3-28 Cut-Off Area of (a) 3 Round Bar and (b) 5 Round Bar

76

The force value (N) was retrieved from the Universal Testing Machine

The Poissonrsquos Ratio (ε) is calculated as

ε =

the values for the Poissonrsquos Ratio are in average around 0297

The Youngrsquos Modulus (E) is calculated as

E =

Where

Stress =

Cross-sectional Area =

where D is the Diameter

The value for D was in average around 1258 mm

The values shown by the computer because there is Slippage phenomena between the Clamp and the

specimen will not be taken into consideration for the elongation strain and Youngrsquos modulus and we will

refer to the values that we have meticulously calculated

77

Chapter 4 AR COATING IN DEPTH

41 Experimentrsquos Purpose and Principles

By means of a vacuum chamber and several other instruments we intend to apply Anti-Reflective

Coating using deposition process to a laser diode and in this way reduce its refraction so as to make it

lose less light in the process of amplification and we can control certain wavelengths we want produced

for certain desired applications in our case we are attempting to re-create a Bose-Einstein Condensate

An optimal BEC apparatus is shown in figure 4-1

Fig 4-1 BEC Apparatus

The main point of this experiment is to build a vacuum chamber system attach all the instrumentation

needed (Vacuum pump deposition meter and voltmeter) and use it to apply AR coating to a laser diode

After we have accomplished the AR coating other team will be in charge of designing the BEC apparatus

and use the results of our research

78

42 Experimentrsquos Equipment

421 Vacuum Chamber

For this research we designed a vacuum chamber whose main body is shown in figure 4-2 Its

dimensions are

Width 240 mm

Length 240 mm

Height 200 mm

Outer Diameter 4 in

Inner Diameter 15 in

Fig 4-2 Vacuum Chamber Main Body

The chamber is made up of 6 pass ways pass way A is the connection with the Laser Deposition

Equipment pass way B is the connection with the Turbo Pump and pass way C is for the connection with

the Deposition Source

A

C

B

79

Pass way C is for the deposition source as mentioned above This is a system where a thermal

resistance is heated by passing a high current through it which heats up a filament boat (made of tungsten)

where the material to be evaporated is place We control the temperature as such that the material will

evaporate and the heat will not cause the filament boat to crack

Because P = Isup2 R (where P is power I is current and R is resistance) to avoid the current to flow

where it is not desired we decided that the material for the Thermocouple shown in figure 4-3 should be

Copper ᴓ 63 mm We choose it that way because Copper has very good heat dissipation characteristics

and the resistance value is low It can reduce the value of the current enough to make the thermocouple to

create heat

Fig 4-3 Thermocouple

To the thermocouple we attach the tungsten filament boat We need to take notice of materials to be

used in this design because when using high current the tungsten filament boar will heat up and so the

material must be able to keep up with the heating potential of tungsten and has a low coefficient of heat

dissipation to avoid the tungsten to fail when heating up and therefore not evaporating Considering all

this we decide to use Stainless Steel

Because this clamp will be assembled inside the chamber after many revisions it was determined it

will have the shape shown in figure 4-4

Fig 4-4 Filament Boat Clamp Design

80

For the tungsten filament boat we bought the product from a distributor The dimensions are

Length 100 mm

Width 10 mm

Height 1 mm

Our thermocouple is 15 in but the pass way C is 4 in so we need to attach a Flange that connects

15in to 4in Because these specifications are quite difficult to achieve by Milling we had to use

electrical wire cutting

For the laser clamping system where the laser that is going to be AR coated will be placed will be

connected to pass way A the assembly is shown in figure 4-5 below

Fig 4-5 Cover Assembly

For this design we used an O-ring instead of a gasket so as to save time The design of the assembly

where the laser will be placed is shown in figure 4-6

Fig 4-6 Upper Cover Inner Assembly

D

E

F

81

Point D is the plate in the assembly where the laser diode will be fixed Because of the easy

processing we decide to use Aluminum and it is screwed to the top cover Point E is the connection for

the Quartz crystal resonator and it is designed in the same as point F in this way the results of the quartz

microbalance system will be more accurate in real time Point F is the final resting place for the laser

diode We use a Thor Labs Base with dimensions of ᴓ 9mm and ᴓ 56mm for two different size laser

diodes It just needs to be plugged in for easy installation

From figure 4-6 we know that the system needs signal system connections and because of the

change in temperature inside the chamber this could affect the functioning of the quartz microbalance so

we also need to install water tubes for cooling This is shown in figure 4-7 below

Fig 4-7 Diagram of Upper Cover Connections

In figure 4-8 we show the Feed through connections and their functions

Fig 4-8 Feed through Diagram

82

1 SQM-160 wire 5 Laser Connection 1 (Vin)

2 SQM-160 (G) 6 Laser Connection 2 (G)

3 K-Type-1 7 Laser Connection 3 (PD)

4 K-Type-2 8 Not In Use

The fully assembled chamber is shown in figure 4-9

Fig 4-9 Fully Assembled Chamber

422 Quartz Crystal Microbalance

For measuring the deposition on our target for coating we used the Inficon SQM-160 RateThickness

Monitor It is an easy to use instrument for measuring many types of thin-film coatings as shown in

figure 4-10

(a) Front Panel (b) Back Panel

Fig 4-10 Inficon SQM-160

83

Table 4-1 shows the technical specifications for this equipment

Number of sensors 2 Standard 4 additional optional

Sensor Frequency Range 40 MHz ~ 60 MHz

Reference Frequency Accuracy 002

Thickness Display Resolution 1 Aring

Thickness Resolution 015 Aring (Std) 0037 Aring (Hi Res)

Density of Stored Films 05-9999 gmcc

Tooling 10-399

Z-Factor 010-1000

Final Thickness 0000-9999k Aring

Measurement Period 15 to 2 sec

Simulation Mode Yes

Frequency Mode Yes

Rate Resolution 011 Arings

Dual Crystal Yes

Etch Mode Yes

Crystal Tooling 10-399

Crystal Fail Min Max 40 to 60 MHz 41 to 61 MHz

Power 100-120 200-240~plusmn10 nominal 20W

Operation Environment 0degC ~ 50degC

0 ~ 80 RH non-condensing

0 ~ 2000 meters

Class 1 Equipment

Pollution Degree 2

Rack Dimensions 885mm x 2127mm x 1969mm

Weight 27 kg

Table 4-1 Inficon SQM-160 RateThickness Monitor Specs

84

To the SQM-160 we need to connect an Oscillator We use the Sigma Instruments Remote Oscillator

Ser No 2 268 as shown in figure 4-11

Fig 4-11 Sigma Instruments Remote Oscillator

The connections diagram is shown in figure 4-12

Fig 4-12 SQM-160 Connections Diagram

85

423 Turbo Pump

For our experiments we used the Pfeiffer TCP 015 Electronic Drive Unit shown below in figure 4-13

Table 4-2 shows the technical specifications for this equipment

(a) Front Panel (b) Back Panel

Fig 4-13 Pfeiffer TCP 015 Electronic Drive

Connection Voltage (100V) 90-112

Mains Frequency 5060 Hz

Start-up Current 22 A

Nominal Frequency 1500 Hz

Rotation Speed 10V = 1500Hz plusmn2

Analog Output Current 10 V = 25 A plusmn 5

Rotation Speed Switchpoint 750 Hz

Works Setting 8 min

Permissible Ambient Temperature 0degC ~ 40degC

Dimensions Front Panel 1285mm x 1063mm

Insertion Length 227mm

Weight 27 Kg

Table 4-2 Pfeiffer TCP 015 Electronic Drive Specs

86

The connections diagram is shown in figure 4-14

Fig 4-14Connections Diagram for Pfeiffer TCP 015

To measure the pressure inside the chamber we use the Granville Phillips 375 Convectron Vacuum

Pressure Controller shown in figure 4-15

(a) Front Panel (b) Back Panel

Fig 4-15 Granville Phillips 375 Convectron

87

Its dimensions are shown in figure 4-16

Fig 4-16 Dimensions of Convectron

Table 4-3 shows the technical specifications for this equipment

Table 4-3 Granville Phillips 375 Convectron Vacuum Pressure Controller Specs

88

424 Multimeter

For our experiment we used the Keithley 2000 Digital Multimeter as shown in figure 4-17

(a) Front Panel (b) Back Panel

Fig 4-17 Keithley Model 2000 6-12-Digit Digital Multimeter

Its technical specifications are shown in table 4-4

Table 4-4 Keithley Model 2000 6-12-Digit Digital Multimeter Specs

89

43 Experiment Procedure

1 Connecting together the equipment and the chamber

(1) We first connect the resonator to the thickness monitor and connect the other side to the

chamber

(2) We now connect the flexible tubes to the turbo pump on one side and to the chamber on the

other

(3) We need to check that tubes are tightly connected to avoid any leaks in the vacuum pumping

process which will not allow us to get to our goal of Torr As shown in figure 4-18

(4) Connect the convectron to the system as shown in figure 4-19

Fig 4-18 checking for leaks using alcohol

Fig 4-19 Convectron attached to System

90

(5) Attach the clamps of the Multimeter to the bottom of the chamber as shown in figure 4-20

(6) Place the Quartz crystal in place

(7) Close tight vacuum chamber

(8) Connect all electrical appliances to power source

Fig 4-20 Multimeter Connections

2 Starting up the System

(1) We turn on all the devices as such Check all systems are ready to function Reset all values

that might be left over from previous tests

(2) Start the thickness monitor and set all values for this experiment In our case we got to testing

the system but not actual coating So we used the simulation mode of the thickness monitor as

shown in figure 4-21

Fig 4-21 Simulation Mode

91

(3) Start the turbo pump Make sure the lid on the vacuum chamber is tightly closed

(4) Start convectron and record initial pressure

(5) Start Multimeter and record initial current

3 Coating Process

(1) If we have the deposition material inside the filament boat the power source for the high

current must be started as well

(2) Record all initial values for thickness current pressure

(3) For an ideal experiment we need a thickness of around 101 nm a pressure of Torr and

a current of 300 A

44 Results

From previous experiments we have shown that we can turn a LED into a laser by means of AR

Coating In figure 4-22 shown below we can compare the actual results of a Diode before and after AR

coating From the blue line we can see that when the diode is at a current of 15mA its light will change

from LED to laser and if we look at the red line its critical current is around 30 to 35 mA

Fig 4-22 AR Coating Comparison for Laser Diodes

This means that the light emitted is not as strong as if the diode had been coated because inside the

chamber there must be some excitation first so the reflectivity of both sides inside the diode must be high

So because of the coating in one of the sides we have opened a door and let the light come out so the

critical current is risen as such and will be higher value than that of before the coating

92

In the following figures we can see the difference between before and after coating in a material The

thickness is around 1016 nm for this material

Fig 4-23 Before Coating

Fig 4-24 After Coating

93

Chapter 5 CONCLUSIONS AND RECOMMENDATIONS

51 Conclusions

For the first part of this independent study taking into consideration the data that came out of our

research and that sent by the provider we can say

1 SUM 23 after heat treatment will unexpectedly develop cracking in the middle of the tensile

testing process and suddenly break

2 Itrsquos possible that in the process of heat treatment to the SUM 23 material the treatment was not

uniform and this will create a pre-loaded moment force on one side that pushes on the other side

of the specimen resulting in material deformation

3 In the process of attaching the strain gauges to the materials it is very easy to make errors due to

poor adhesion or sudden removal in the tensile testing process

For our second part of the independent study the following can be made

1 At the beginning of this independent study we had no idea what Bose-Einstein Condensate was

or what was its purpose After much literature we finally comprehended the basic principles to

put into practice for our research

2 Our systemrsquos basic working principles and equipmentrsquos complexity are a little difficult to grasp

but hopefully we were able to understand enough of it

3 Theoretically from relation between the power and current we can know the advantages and

disadvantages of AR Coating

4 We were able to assemble the system and run test on its functions Even though we were able to

do this there is still much more work left to do with this system

52 Recommendations

For the Tensile Testing the following can be said

1 Ask the provider to check on the process of heat treatment on the SUM 23 material and give

them the information we have gathered through our test so they can correct for the mechanical

properties found if any change is needed

2 To avoid the problem of the inaccuracy of the poor adhesion of strain gauges we can attach

multiple strain gauges to the same one specimen so as to correlate data and improve our results

For the AR Coating the following can be said

1 We need to make sure that there are no physical defects on the main body of the chamber so as to

achieve maximum efficiency in the vacuum process If there was then the vacuum will arrive to

certain point and then start to decrease

2 It would be preferable to add some sort of visual aid that will allow the user to check the inside of

the chamber without actually opening it This will help us determine at what times we should

manipulate the current to better evaporate the substrate

94

REFERENCES

[1] A L Window Strain Gauge Technology Elsevier Applied Science London and New York 2nd

Edition 1992

[2] CC Perry and HR Lissner Strain Gauge Primer McGraw-Hill Book Co Inc New York 1955

[3] James W Dally William F Riley McGraw-Hill 1978

[4] University of Colorado Boulder BEC - What is it and where did the idea come from

httpwwwcoloradoeduphysics2000becwhat_is_ithtml

[5] Ultraslow Light amp Bose-Einstein Condensates Two-way Control with Coherent Light amp Atom

Fields Harvard Hau Lab Dr Lene Vestergaard Hau Optics amp Photonics News 16 1995

[6] The Art of Taming Light Ultra-slow and Stopped Light Harvard Hau Lab Dr Lene

Vestergaard Hau Europhysics News 2004

[7] Nonlinear Optics Shocking Superfluids Harvard Hau Lab Dr Lene Vestergaard Hau Nature

Physics 2007

[8] Model P3 Strain Indicator and Recorder Instruction Manual Vishay Micro-Measurements 2005

[9] Granville-Phillips Series 375 Convectron Vacuum Gauge Controller Instruction Manual Brooks

Automation 2008

[10] Effect of Film Thickness on the Validity of the Sauerbrey Equation for Hydrated Polyelectrolyte

Films Vogt Lin Wu White 2004

[11] Quartz Crystal Microbalance Study of DNA Immobilization and Hybridization for DNA Sensor

Development Chang Zhao 2008

[12] Installation of Strain Gages with SR-4 PrecoatAdhesive Vishay Micro-Measurements 2005

[13] Strain Gauge Measurement ndash A Tutorial National Instruments 1998

[14] Correlation between Vickers Hardness Number and Yield Stress of Cold-Formed Products

Yavuz Tekkaya

[15] httpsenwikipediaorg

Page 19: PC Hinge Materials Testing and AR Laser Diode Coating

19

222 Rockwell Scale HR

The Rockwell scale is a hardness scale based on the indentation hardness of a material The Rockwell

test determines the hardness by measuring the depth of penetration of an indenter under a large load

compared to the penetration made by a preload The indenter is forced into the specimen under a

preliminary load When equilibrium is reached a measuring device follows the movements of the

indenter and responds to changes in depth of penetration of the indenter While the preload is still being

applied additional major load is applied resulting in increased penetration When equilibrium is reached

again the major load is removed but the preload is maintained Removing the major load allows partial

recovery and reduces the depth of penetration The permanent increase in depth of penetration resulting

from the application and removal of the major load is used to calculate the Rockwell number using the

relation

HR = E ndash e

Where E is a constant depending on the form of the indenter 100 units for diamond indenter and 130

units for steel ball indenter e is the permanent increase in depth of penetration due to the major load

measured in units of 0002mm

Fig 2-7 Rockwell Indentation

When testing materials indentation hardness is related linearly to the tensile strength The important

relation permits economically important nondestructive testing of bulk metal deliveries with lightweight

equipment like the Rockwell tester shown below in figure 2-7

Fig 2-8 Rockwell Hardness Tester

20

There are different scales denoted by a single letter that use different loads or different indenters

The result is a dimensionless number denoted as HR X where X will be the letter denoting the scale as

shown below in table 2-1

Table 2-1 Rockwell Hardness Test Scale

Differential depth hardness measurement was first conceived in 1908 by Viennese professor Paul

Ludwik It eliminated the errors associated with the mechanical imperfections of the system such as

backlash and surface imperfections in the specimen Rockwell testing has an advantage over Brinell

testing because the latter was slow itrsquos not useful on fully hardened steel and left too large an impression

to be considered nondestructive

The tester was co-invented by Hugh M Rockwell and Stanley P Rockwell The requirement for this

tester was to quickly determine the effects of heat treatment on steel bearing races

21

223 Vickers Hardness Test HV

This is a type of microindentation hardness test where a diamond indenter of specific geometry is

impressed into the surface of the test specimen using a known applied force ranging from 10 to 1000

grams This type of tests usually has forces of 2N and produce indentations of about 50μm They can be

used to observe changes in hardness on the microscopic scale It is difficult to standardize the

microhardness measurements because it has been found that the microhardness of almost any material is

higher than its macrohardness The values also vary with load and work-hardening effects of materials

The Vickers test is often easier to use than other hardness tests because the required calculations are

independent of the size of the indenter and the indenter can be used for all materials It can be used for all

metals and has one of the widest scales among hardness tests The unit of the Vickers test is denoted as

HV and can be converted to units of Pascal (Pa) but it is not a measurement of pressure The hardness

number is determined by the load over the surface area of the indentation and not the area normal to the

force

A square-based pyramid shaped diamond is use as the indenter It has been established that the ideal

size of a Brinell impression was 38 of the ball diameter As two tangents to the circle at the ends of a

chord 3d8 long intersect at 136plusmn05deg it was decided to use this as the angle of the indenter giving an

angle to the horizontal plane of 22deg on each side The HV number is determined by the ratio FA where F

is the force applied to the diamond in kgf and A is the surface area of the resulting indentation in mmsup2 A

can be determined by the relation

A =

Where A is the surface area of indentation and d is the average length diagonal left by the indenter

This can be approximated as

A =

Then the Vickers Number is

HV =

=

Vickers hardness number is reported as xxxHVyy or xxxHVyyzz (if duration of applied force differs

from 10s to 15s) where xxx are replaced by the hardness number yy is the load in kg and zz indicates

loading time The values are generally independent of test force

The test was developed in 1921 by Robert L Smith and George E Sandland at Vickers Ltd as an

alternative to Brinell method to measure the hardness of materials

22

Fig 2-9 Vickers Indentation Fig 2-10 Vickers Hardness Tester

23 AR Coating

231 Bose-Einstein Condensate

The Bose-Einstein Condensate or BEC is a state of matter of a dilute gas of bosons cooled to

temperatures very near absolute zero around 0K or -27315degC Under such conditions a large fraction of

the bosons occupy the lowest quantum state where the quantum effects become apparent on a

macroscopic scale This gave birth to the Bose-Einstein Statistics which are the rules that govern the

behavior at this state It is one of the two possible ways in which a collection of indistinguishable particles

may occupy a set of available discrete energy states The aggregation of particles in the same state

accounts for the cohesive streaming of laser light and the frictionless creeping of superfluid helium (an

application discussed later) Bose and Einstein recognized that a collection of identical and

indistinguishable particles can be distributed this way This theory applies only to those particles not

limited to single occupancy of the same state particles that do not obey the Pauli Exclusion Principle

restrictions Such particles are the Bosons named after the statistics that correctly describe their behavior

This phenomenon was first predicted by Satyendra Nath Bose around 1924 when he considered how

groups of photons behave He then asked Albert Einstein for help publishing his discoveries to which

Einstein agreed and gave follow up supporting these findings The resulting efforts became the concept of

a Bose gas governed by the Bose-Einstein Statistics described above Einstein demonstrated that cooling

bosonic atoms to a very low temperature would cause them to condense into the lowest accessible

quantum state resulting in a new form of matter

The first gaseous condensate we produced by Eric Cornell and Carl Wieman at the University of

Colorado at Boulder NIST ndash JILA lab sung a gas of rubidium atoms cooled to 170 nK which earned

them the 2001 Nobel Prize in physics together with Wolfgang Ketterle from MIT The transition to BEC

occurs below a critical temperature which for a uniform three dimensional gas consisting of

non-interacting particles with no apparent internal degrees of freedom is given by

23

Tc =

(

)

asymp 33125

Where Tc is the critical temperature n is the particle density m is the mass per boson h is the

reduced Planck constant k is the Boltzmann constant and ζ is the Riemann zeta function

There are two classes of elementary particles defined by whether their quantum spin is a nonnegative

integer or an odd half integer A Bose-Einstein Condensate is shown below in figure 2-11

Fig 2-11 Bose Einstein Condensate at different scales

Bosons are the particles whose quantum spin is a nonnegative integer (s = 0 1 2 etc) Examples of

bosons include fundamental particles (Higgs Boson Photons W and Z Bosons Gluons Gravitons etc)

composite particles (Mesons Hadrons Nuclei and Atoms of Carbon-12 and Helium-4) and

quasi-particles Bosons are considered force carrier particles The Bosons differ from Fermions in that

there is no limit to the number that can occupy the same quantum state This is called the Pauli Exclusion

Principle

The Pauli Exclusion Principle says that no two identical fermions may occupy the same quantum state

simultaneously in other words this means that the total wave function for two identical fermions is

anti-symmetric with respect to exchange of the particles This means that no two electrons in a single

atom can have the same four quantum numbers

Fermion is any particle characterized by Fermi-Dirac Statistics and follows the Pauli Exclusion

Principle described above Quarks Leptons and composite particles (Hadrons Nuclei and Atoms of

Carbon-13 and Helium-3) made of an odd number of these are considered Fermions It can be an

elementary particle such as the electron or a composite particle such as the protons Following the Pauli

24

Exclusion Principle only one fermion can occupy a particular quantum state at any given time If multiple

fermions have the same spatial probability distribution then at least one property of each fermion must be

different Fermions are usually associated with matter because composite fermions are key building

blocks of matter (neutrons and protons)

Fermionsrsquo behavior by the Fermi-Dirac Statistics which describes the energies of single particles in a

system comprising of many identical particles It applies to identical particles with half-odd integer spin

in a system of thermal equilibrium The particles in the system are assumed to have negligible mutual

interaction This allows the many-particle system to be described in terms of single-particle energy states

The result is the Fermi-Dirac distribution of particles over these states and includes the condition that no

two particles can occupy the same state which has considerable effect on the properties of the system

In quantum mechanics the position of an object is uncertain An object has a definite probability of

being at any given point in space This probability is encoded in the wave function mentioned earlier If

one concentrates a large number of identical bosons in a small region then it is possible for their wave

functions to overlap so much that the bosons lose their identity When this happens thatrsquos a Bose-Einstein

Condensate It is only possible at very low temperatures because at high temperatures the individual

bosons have small wave functions and move rapidly which causes them to fly apart

For now applications are still restricted because there are still some setbacks regarding BECs They

are extremely fragile they are being produced in small quantities with just a few million atoms at a time

and finally they can only be made from certain types of atoms Some examples are the atom laser Ketterle

in which a conventional light lase emits a beam of coherent photons this means they are all in phase and

can be concentrated to an extremely small bright spot BECs can slow down light as demonstrated by

Prof Lene Hau PhD in 2001 by the use of a superfluid [7] These manipulations could develop into

new types of telecommunications technology optical storage and quantum computing

BECs are related to super-fluidity and super-conductivity Super-fluidity is the state of matter in

which the behavior is that of a fluid with zero viscosity It was discovered in liquid helium but now it has

applications in astrophysics high-energy physics and theories of quantum gravity

Super-conductivity is a phenomenon of exactly zero electrical resistance and expulsion of magnetic

fields occurring in certain materials when cooled below a characteristic critical temperature A

super-conductor is shown below in figure 2-12

Fig2-12 Super Conductor

25

232 AR Coating Basic Principles

Anti-reflective (AR) coating is a type of optical coating applied to the surface of lenses and other

optical devices (in our case we planned to apply it to a laser diode) to reduce reflection This improves

the efficiency of the system since less light is lost The primary benefit is the elimination of the reflection

itself

When light the medium (glass) it will produce reflection if 100 of the light comes from the air and

enters the glass because therersquos a difference between the index of refraction some of the light will go out

and when the light is coming out of the glass into the air once again because of the difference between

index of refraction some of the light wonrsquot be able to pass through the medium

When the light makes the first trip into the glass there was a loss of about 4 in the reflection and

when the light makes the trip back outside there was another loss of about 4 so when we assume that

100 of the light interacts with the medium actually therersquos just about 92 acting (we neglect the light

absorbed by the glass around 05) To illustrate this idea please refer to figure 2-13

Fig 2-13 Simple Model for Light in Glass Medium

When we apply the AR Coating the light that enters will only have a loss of about 05 and when

making the trip back outside again only 05 of light is loss so we get the result of increasing the light

passing through up to 99 (again neglecting the light absorbed by the glass around 05) To illustrate

this idea please refer to figure 2-14

26

Fig 2-14 Simple Model for Light in Glass Medium after AR Coating

The AR Coating can reduce reflection of incoming light In the case that light hits perpendicular to

the surface of the medium the intensity of the reflection can be calculated using the Reflection

Coefficient

Where n0 and ns are the refractive indices of the first and second media respectively The value of R

varies from 0 (no reflection) to 1 (all light reflected) and is usually quoted as a percentage

Complementary to R is the transmission coefficient or Transmittance If absorption and scattering are

neglected then the value of Transmittance is always 1-R then if a beam of light with intensity I is

incident on the surface a beam of intensity RI is reflected and a beam with intensity TI is transmitted to

the medium

The optimal value is called the Optimal Index of Refraction and is described as

For glass with ns around 15 in air (n0 around 10) then the optimum refractive index will be n1 =

1225

To reduce the refraction in this case we now mean the one that is produced inside the chamber of the

Laser diode the easiest way is to apply a low reflectivity AR coating on the surface of the laser To

measure the appropriate thickness of the coating layer we can use the equations described above By

applying a coat exactly

thickness film we can assure that a certain wavelength is transmitted The

27

reflected waves from the back of the glass medium will be half a wavelength out of phase So they

interfere destructively Because all reflected waves are interfered the maximum amount of light passes

through the coating Please refer to figure 2-15 to illustrate this idea

Fig 2-15 Light Passing through AR Coat and Glass

The most common process to attain this final product is by vacuum deposition For the best coating

results we need to lower the pressure inside the vacuum system to torr

Fig 2-16 Lens without (Top) and With (Bottom) AR Coating

28

233 Laser Diode Basic Principles

A laser diode is a laser whose active medium is a semiconductor similar to that found in

light-emitting diodes (LEDs) Please refer to figure 2-17 The most common type of laser diode is formed

from a p-n junction and powered by injected electric current

Fig 2-17 Laser Diode

Laser diodes are formed by doping a very thin layer on the surface of a crystal wafer The crystal is

doped to produce the n-type region and a p-type region one above the other

By referring to figure 1-2 we can see the basic structure of a working laser When the laser diode has

a current passing through it the light will get excited inside its gain medium and then will start to

resonate this process is called pumping The current exceeds the critical current and then it comes out as

laser light Please refer to figure 1-3 Since we use an external cavity laser we need to apply the AR

coating to the diode and adjust a diffraction grating The laser light comes out the diode and bounces on

the grating making the resonance externally and this becomes the ldquocavityrdquo as shown in figure 2-18

Fig 2-18 Tunable Laser Basic Configuration

29

The most important feature of the external cavity laser is that we can adjust the wavelength easily just

by changing the diffraction gratingrsquos angle and in the end this is the output wavelength of the laser For

different wavelengths there will be different levels of visible light as shown in figure 2-19

Fig 2-19 Light Spectrum

234 Quartz Microbalance System

A Quartz Crystal Microbalance is an instrument that measures a mass per unit area by measuring the

change in frequency of a quartz crystal resonator The resonance is disturbed by the addition or removal

of a small mass due to oxide growthdecay or film deposition (which is the case in our study) at the

surface of the acoustic resonator The QCM can be used under vacuum in gas phase and more recently in

liquid environments It is useful for monitoring the rate of deposition in thin film deposition systems

under vacuum Frequency measurements are easily made with high precision

For our research we used the Sigma Instruments SQM-160 RateThickness Monitor shown in figure

2-20

Fig 2-20 Front and Back Panels of SQM-160

30

The microbalance uses Quartz as the resonator Quartz is one member of the family of crystals that

experience the Piezoelectric Effect

Piezoelectricity is the charge that accumulates in certain solid materials in response to applied

mechanical stress It means electricity resulting from pressure It was discovered in 1880 by Jacques and

Pierre Curie It is understood as the linear electromechanical interaction between the mechanical and the

electrical state in crystalline materials with no inversion symmetry It is a reversible process in that

materials exhibiting direct piezoelectricity also exhibit the reverse This means that the internal generation

of electrical resulting from applied mechanical force and vice versa

By using the piezoelectric effect we can probe as an acoustic resonance by electrical means Applying

alternating current to the quartz crystal induces oscillations This creates a shear wave We can use these

qualities to determine the resonance frequency at high accuracy

The frequency of oscillation of the crystal is partially dependent in the thickness of the crystal During

normal operation all the variables are held constant so a change in thickness correlates directly to a

change in frequency As mass is deposited or etched away the thickness increases or decreases and so the

frequency of oscillation changes accordingly With some simplifying assumptions the frequency change

can be quantified and correlated precisely to the mass change using the Sauerbreyrsquos Equation

Developed by G Sauerbrey in 1959 it is a method for correlating changes in the oscillation

frequency of a piezoelectric crystal with the mass deposited on it It is defined as below

Where f0 is the Resonant frequency Δf is the Frequency change Δm is the mass change A is the

piezoelectrically active area of the crystal q is the Density of quartz (2648 gcmsup3) and μq is the Shear

modulus of quarts(2947x gcmssup2)

Because the film is treated as an extension of thickness Sauerbreyrsquos equation only applies to systems

in which the following 3 conditions are met

Deposited mass must be rigid

Deposited mass must be distributed evenly

The frequency change

lt002

If the change is greater than 2 the Z-match method must be used to determine the change in mass

It is defined as

Where fL is the frequency of the loaded crystal fU is the resonant frequency Nq is the frequency

constant (1668x HzAring) Δm is the mass change A is the piezoelectrically active area of the crystal

31

q is the density of quartz Z is the method constant f is the density of film μq Is the shear modulus of

quarts and μf is the shear modulus of film

The Sauerbrey equation cannot be applied to systems under liquid medium

The crystals are seed crystals plated with gold on both top and bottom for applications A crystal is

shown in figure 2-21 The QCM consists of a thin piezoelectric plate with electrodes evaporated on both

sides Due to the piezoelectric effect AC voltage across the electrodes induces a shear deformation and

vice versa The electromechanical coupling provides a simple way to detect an acoustic resonance by

electrical means

The Z also called Z-factor is a constant value for different materials and it is shown together with the

density of different materials in table 2-2 below

Fig 2-21 QCM Crystals

The Oscillator of the SQM-160 is shown in figure 2-22 and the equivalent circuit for the Resonant

Oscillator is shown in figure 2-23

Fig 2-22 SQM-160 Oscillator

32

Fig 2-23 Oscillator Circuit

33

Table 2-2 Z-Ratios for Different Materials

Table 2-2 Continued

34

Table 2-2 Continued

35

Table 2-2 Continued

36

Table 2-2 Continued

37

Table 2-2 Continued

38

Table 2-2 Continued

235 Vacuum Chamber System

Vacuum Evaporation is the process of depositing thin films of materials onto surfaces The technique

consists of pumping a vacuum chamber to pressures of less than torr and heating a material to

produce a flux of vapor in order to deposit the material onto a surface The material to be vaporized is

typically heated until its vapor pressure is high enough to produce a flux several Angstrom per second by

using an electrically resistive heater or bombardment by a high voltage beam The process was invented

by Henri Nestle in 1886 for food industry

In here the system has been pumped to a vacuum of Torr When a high current is passed

through the filament boat the filament boat is heated over the desired metal evaporation temperature and

so evaporation starts When the evaporation process is finished and the metal cools down crystals

condensate in the surface of the wafer From the weight of the evaporated material the distance between

the filament boat and the wafer we are able to calculate the deposition thickness and we can also use the

mass detector follower like the Quartz crystal resonator microbalance system In the process of

evaporation we usually use a board in between the filament boat and the wafer This is because before we

arrive to the desired evaporation temperature there will be some impurities that will be vaporized in the

controlled environment so we first use a small current and the board in between to get rid of those

impurities and this raises the purity of the deposition material

39

A vacuum evaporation system is shown in figure 2-24

Fig 2-24 Vacuum Evaporation System

Rough Vacuum 760 ~ 1 torr

Medium Vacuum 1 ~ torr

High Vacuum ~ torr

Ultra-High Vacuum Lower than torr

Table 2-3 Classification of Vacuum

For our study we need to use a Turbo Pump A regular turbo pump is shown in figure 2-25

Fig 2-25 Turbo Pump

For our research we used the Pfeiffer TCP 015 Electronic Drive Unit and Granville Phillips 375

Convectron shown below in figure 2-26

40

Fig 2-26 Control and Measurement Equipment

The electronic drive controls the turbo pump and the Convectron measures the pressure inside our

chamber The turbo pump is a type of vacuum pump used to maintain high vacuum Most turbo pumps

are centrifugal When we start the pumping we need to use a mechanical pump so as to decrease the

pressure inside the system from constant atmospheric pressure to torr and then the use dispersion

pump to continue the vacuum until we get to the desired pressure We need to notice though when we

start the dispersion pump we canrsquot turn off the mechanical pump and they both need to run together If

we need to turn off the pumping we first turn off the dispersion pump wait for it to completely stop and

then turn off the mechanical pump

Our completely assembled system is shown in figure 2-27 below

Fig 2-27 Complete System

41

Chapter 3 TENSILE TESTING IN DEPTH

31 Experimentrsquos Purpose and Principles

By means of Universal testing machine and Strain gauges we were able to observe discuss and

analyze the phenomena created when a specimen of certain material is manipulated under an external load

and determine the stress strain and deformation values later we can use the graphing methods of

stress-strain diagram to describe it

The main point of this experiment is that after the tensile specimen is tested use computer analysis

and the actual strain data and after statistical adjustment make the final results report (Tensile testing

experiment is in accordance with ASTM E8)

32 Experimentrsquos Equipment

321 Universal Testing Machine

For the materials testing experiment part of this research we use a Universal Testing Machine as

shown in figure 31 The maximum load it can apply is 100 Ton After the test specimen is secured on the

device with the use of instrumentation the load exerted and the effects of this become apparent on the

specimen and even the smallest of changes can be recorded For our research we used the Chun Yen

Testing Machines Co Ltd 100 Ton Micro Computer Universal Tensile Tester

Fig 31 Universal Testing Machine

42

Table 31 shows the specifications for this machine

Max Capacity 100 Ton

Accuracy plusmn1

Tension (mm) Max Space 1150mm

Grip for Rod 20-70mm

Ram Stroke 250mm

Effective Column Interval 940mm

Crosshead Speed 300mmmin

Testing Speed 0-50mmmin

Volume of Machine 1700times1000times3350mm(LtimesWtimesH)

Volume of Control Panel 1000times800times1500mm(LtimesWtimesH)

Weight 8000kg

Power 3∮220V 20A

Computer AMD K6-2-350

OS Windows XP

Screen 15rdquo CRT

Table 3-1 Chun Yen Testing Machine Specs Table

The connections diagram is shown in figure 3-2

Fig 3-2 Diagram for System Connections

43

When the test specimen is placed when the external force is applied the Load Cell can measure the

size of the applied force and the Encoder measures the expansion rate of change The Local Controller

receives all the information from the 2 units after arranging the results they are displayed in the

computer and they can be afterwards submitted for more complex analysis such as Finite Element

Analysis and we can get the Stress-Strain Diagram

322 Strain Measurement Equipment

The equipment used in our research provides a four-channel measurement that means we can use up

to 4 strain gauges at a time to do our measurements and provides 3 different bridge arrangements as

shown in figure 3-3

(a) (b) (c)

Fig 3-3 Input Connections for Strain Indicator

Figure 3-3 (a) is the Quarter Bridge (b) is the Half Bridge and (c) is the Full Bridge and Transducers

For our study we used the Quarter Bridge and use the Strain Gauge values to decide the position of the

connecting wires The Strain indicator is shown in figure 3-4

Fig 3-4 Vishay Micro-Measurements Model P3 Strain Indicator and Recorder

44

Input Connections Tool Free eccentric lever release

4-channel input

Wire diameter16-28AWG

Bridge Configurations Quarter- Half- and Full Bridge

Bridge Impedance 60-2000Ω

Display 128 64 pixel FSTN positive gray LCD

Data Conversion AD Converter filter

Measurement Range Resolution Strain Range plusmn155mVV

Resolution plusmn00005mVV

Measurement Accuracy plusmn01 of reading plusmn3 counts

Gage Factor Control 0500-9900

Balance Control Software either manual or automatic

Bridge Excitation 15VDC nominal

Communication Interface USB Cable Included

Data Storage Removable Media Card

Shunt Calibration Across bridge completion resistors controlled

by software When Gage Factor=200

120Ω350Ω1000Ω

Analog Output Value 0 to 25V max

Ranges plusmn320 microε plusmn3200 microε plusmn32000 microε

Error 05 output voltage +5mV

Max Error 14 output voltage + 20mV

Update rate 480 samplessec

Output Load 2000Ω

Power Battery Two Alkaline D cells

Battery life 400 hours typ

USB 5V 100mA

Operational Environment Temperature 0-50

Humidity Up to 90 Non-condensing

Case Aluminum Alloy

Size and Weight 228times152times152(mm) 20(kg)

Table 3-2 Vishay Micro-Measurements Model P3 Strain Indicator and Recorder Specs

45

323 Strain Gauge

The strain gaugersquos main basic principle is to use a resistancersquos characteristics to measure the strain

The inside connections of the strain indicator are shown in figure 3-5

Fig 3-5 Inner Connections

As shown above this is a quarter-bridge connection We connect equal-length 3 wires to the 2

connections allowed by the strain gauge wire 1 and 3 can be used to cancel out the effects of temperature

to the resistance and because of the addition of wires 1 and 3 wire 2 can directly measure the experiment

results from the strain gauge and therefore the strain developed with no influence of temperature

If there were no two measuring leads then the relations will be

R 4 =R g +2R L

Where Rg is the Strain Gauge Value and RL is the wire resistance then

4

4

R

R=

Lg

g

RR

R

2

=

gL

gg

RR

RR

21

amp

4

4

R

R=

g

g

R

R(1- L)

Where L is the Signal Loss Factor and so

L =gL

gL

RR

RR

21

2

g

L

R

2R if

g

L

R

2Rltlt1

46

(Actual Value R g =120R L =08g

L

R

2Ris always much smaller than 1)

R 4 =R g +2R LR 2 =R 3 =rR gR 1 =R g 32 RR =0

V 0 =V 2)1( r

r

(

4

4

R

R-

1

1

R

R)

The first term describes loss attenuation effects second term describes loss of balancing capabilities

effects

V 0 =V 2)1( r

r

[

)2

(Lg

g

RR

R

+

T

Lg

g

RR

R

)

2( + T

Lg

L

RR

R

)

2

2( -(

g

g

R

R) T ]

The first term describes loss attenuation effects and loss of balancing capabilities effects the second

third and fourth terms describe the temperature effects on the wire

For the three-wire method we have

L =gL

gL

RR

RR

1

g

L

R

R if

g

L

R

Rltlt1

V 0 =V 2)1( r

r

[

)(Lg

g

RR

R

+

T

Lg

g

RR

R

)( + T

Lg

L

RR

R

)

2( -

T

Lg

g

RR

R

)( - T

Lg

L

RR

R

)

2( ]

V 0 = V2)1( r

r

)(

Lg

g

RR

R

In the last four terms inside parenthesis we can see the effects of temperature being cancelled out and the

effect on first term is not great so this is the reason why in our research we use three wires

47

324 Specimen Measurements

The tensile specimens used in this research are compliant of ASTM E8 Tensile parameters as shown

in figure 3-6

Fig 3-6 Tensile Specimen

Diameter

D(mm)

Gauge

Length

G(mm)

Smallest

Arc

Radius

R(mm)

Shortest

Area

A(mm)

Total

Length

L(mm)

Clamping

Area

Length

B(mm)

Clamping

Area

Diameter

C(mm)

Bar 125 02 625 01 gt10 gt75 ~ 145 ~ 35 20

Table 3-3 Specifications for Round Bar

33 Experiment Procedure

1 Attaching the Strain Gauge to the Tensile Specimen

(1) Prepare 1 ASTM E8 compliant tensile specimen round bar as shown in figure 3-7

(2) Prepare Strain Gauge as those described in table 3-4

(3) Prepare other consumables and adhesive agent such as epoxy adhesive or

cyanoacrylate adhesive as shown in figure 3-8

48

Fig 3-7 Actual Tensile Specimen

Fig 3-8 Other Materials Used (Such as Alcohol gauze transparent tape adhesive)

Gage Type

EA-06-120LZ-120E

Resistance in ohms at 24∘C

1200plusmn03

Gage Factor at 24∘C

2075plusmn05

Transverse Sensitivity at 24∘C

(+07plusmn02)

Table 3-4 Specifications for Strain Gauge

2 Attaching Strain Gauge

As shown in following figures we shall explain the attachment of the strain gauge

(1) Use sand paper and a rasp to clean thoroughly the surface where the strain gauge will be

attached to

49

(a)

(2) Use alcohol to wash the surface where the strain gauge will be attached and use gauze to rub

it off

(b)

(3) Find a clean surface and clean it with alcohol and gauze

(c)

(4) Place the strain gauge in the clean surface Use a piece of transparent tape on top of the strain

gauge after securely placed rip it off the surface carefully

50

(d)

(5) Use a piece of white paper to mark the place where the strain gauge will be attached and in

this way we can make sure that the strain gauge will be placed as horizontally and vertically

correct as possible

(e)

(6) In the place where we had our mark place the strain gauge

(f)

(7) Carefully lift one side of the tape and apply some of the adhesive agent to both the strain

gauge and specimenrsquos surface

(g)

51

(8) We need to make sure that the gauge and the specimen will be firmly attached so we gently

apply pressure with our thumb

(h)

(9) After the adhesive is fully dry we can carefully rip off the tape

(i)

(10) We need to do the whole process twice one for the horizontally placed strain gauge and one

for the vertically placed strain gauge

52

(j)

(11) We now proceed to solder the wires to the strain gauge

(k)

(12) After soldering we use a Volt Multimeter to measure that there is no contact between wires

If there is none then the specimen is ready for testing

(l)

(13) We now need to measure a 5cm distance and mark it to check and compare the elongation

before and after the tensile testing

(m)

53

Fig 3-9 Specimen-Strain Gauge Process

3 Tensile Test

(1) Enter the computer application that controls the tensile testing machine

(2) Turn on the tensile testing machine main switch

(3) Adjust the hydraulic pump to go back to its original position

(4) Bring the lowering motor down to a distance enough so as to attach the tensile specimen to the

system open the clamps and secure the specimen

(a)

(5) Connect all the necessary wires to the strain indicator equipment

54

(b)

(6) Start the ascending motor and wait for the expansion

(c)

Fig 3-10 Specimen-Tensile Testing Process

4 Start the Test

(1) Enter the software application and enter some variables needed for the experiment in the

specific screen

(2) Go back to the main screen and press the [測試] (measure) button to start the test and auto

recording in the software

(3) After the specimen breaks the mechanical device will automatically stop and ask the user to

enter the total displacement We take out the specimen from the testing machine and adjust the

machinersquos position back to its original position

(4) Save the results information

(5) Record the results from the strain indicator

34 Results

From this experiment we can get the Poissonrsquos Ratio Youngrsquos Modulus and Yield Strength etc and

because of the slippage phenomenon in the clamp at the moment of the test then the Elastic Limit will

display some yield phenomena So omit any undesirable results we just take the Yield portion of the

results as reference

In the process of the experiment the most important part to attend to is the attaching of the strain

gauge because the gaugersquos purpose is to measure the strain developed during the test and this strain

might be very small If the gaugersquos angle change during the test ie is not well attached this will affect

the accuracy of the measurements of Poissonrsquos ratio and Youngrsquos modulus

55

The materials provided by the manufacturer are SUM 23 and SUM 43 steel round bars and these two

types of materials have been through different heat treatment processes so they can be sub-divided

further into untreated material heat-treated material and black surface heat treated material for the two

materials with heat treatment the treatment process and finished are different In the end we only have

the mechanical properties that were calculated after our research of these materials

All of the specifications are identical to those shown in figure 3-6

341 SUM 23

Fig 3-11 SUM 23 Untreated Material

Number 7 10

Hardness(HRB) 74 75

Yield Stress (MPa) 448 440

Tensile Strength (MPa) 544 560

Poissonrsquos Ratio 029 027

Youngrsquos Modulus (GPa) 203 210

Cut-off Area Shrinking () 42 41

Elongation () 1125 1011

Table 3-5 Mechanical Properties of SUM 23 Untreated

56

Stress-Strain Diagram

(a)

(b)

57

Fig 3-12 Stress-Strain Diagrams for (a) 7 Round Bar and (b) 10 Round Bar

Cut-Off Area

(a)

(b)

Fig 3-13 Cut-Off Area of (a) 7 Round Bar and (b) 10 Round Bar

58

SUM 23 Nickel Round Bar

Fig 3-14 SUM 23 Nickel Material

Number 1 2 3 4

Hardness(HRB) 48 50 49 48

Yield Stress (MPa) 370 370 380 400

Tensile Strength (MPa) 455 451 450 450

Poissonrsquos Ratio 028 046 029 026

Youngrsquos Modulus (GPa) 243 303 246 206

Cut-off Area Shrinking () 803 803 726 601

Elongation () 566 65 602 647

Table 3-6 Mechanical Properties of SUM 23 Nickel

59

Stress-Strain Diagram

(a)

60

(b)

(c)

(d)

61

Fig 3-15 Stress-Strain Diagrams for (a) 1 Round Bar (b) 2 Round Bar (c) 3 Round Bar and (d)

4 Round Bar

Cut-Off Area

(a)

(b)

62

(c)

(d)

Fig 3-16 Cut-Off Area of (a) 1 Round Bar (b) 2 Round Bar (c) 3 Round Bar and (d) 4 Round

Bar

63

SUM 23 Black Surface Round Bar

Fig 3-17 SUM 23 Black Surface Material

Number 1 2 3

Hardness(HRB) 51 50 51

Yield Stress (MPa) 378 371 369

Tensile Strength (MPa) 467 465 464

Poissonrsquos Ratio 03 016 04

Youngrsquos Modulus (GPa) 215 266 266

Cut-off Area Shrinking () 986 94 848

Elongation () 748 805 761

Table 3-7 Mechanical Properties of SUM 23 Black Surface Material

64

Stress-Strain Diagram

(a)

(b)

65

(c)

Fig 3-18 Stress-Strain Diagrams for (a) 1 Round Bar 2 Round Bar and (c) 3 Round Bar

Cut-Off Surface

(a)

66

(b)

(c)

Fig 3-19 Cut-Off Surface of (a) 1 Round Bar 2 Round Bar and (c) 3 Round Bar

67

342 SUM 43

Fig 3-20 Untreated SUM 43 Untreated Material

Number 1 5

Hardness(HRB) 76 75

Yield Stress (MPa) 572 594

Tensile Strength (MPa) 743 785

Poissonrsquos Ratio 027 029

Youngrsquos Modulus (GPa) 200 202

Cut-off Area Shrinking () 338 2944

Elongation () 857 894

Table 3-8 Mechanical Properties of SUM 43 Untreated

68

Stress-Strain Diagrams

(a)

(b)

Fig 3-21 Stress-Strain Diagrams for SUM 43 (a) 1 Round Bar and (b) 5 Round Bar

69

Cut-Off Area

(a)

(b)

Fig 3-22 Cut-Off Area of SUM 43 (a) 1 Round Bar and (b) 5 Round Bar

70

SUM 43 Nickel Round Bar

Fig 3-23 SUM 43 Nickel Material

Number 4 5

Hardness(HRB) 51 50

Yield Stress (MPa) 1580 1544

Tensile Strength (MPa) 1639 1625

Poissonrsquos Ratio 03 028

Youngrsquos Modulus (GPa) 194 201

Cut-off Area Shrinking () 1697 137

Elongation () 376 265

Table 3-9 Mechanical Properties of SUM 43 Nickel

71

Stress-Strain Diagrams

(a)

(b)

Fig 3-24 Stress-Strain Diagrams for (a) 4 Round Bar and (b) 5 Round Bar

72

Cut-Off Area

(a)

(b)

Fig 3-25 Cut-Off Area of (a) 4 Round Bar and (b) 5 Round Bar

73

SUM 43 Black Surface Material

Fig 3-26 SUM 43 Black Surface Material

Number 3 5

Hardness(HRB) 56 56

Yield Stress (MPa) 1416 1361

Tensile Strength (MPa) 1591 1402

Poissonrsquos Ratio 029 031

Youngrsquos Modulus (GPa) 200 202

Cut-off Area Shrinking () 139 124

Elongation () 24 24

Table 3-10 Mechanical Properties of SUM 43 Black Surface Material

74

Stress-Strain Diagrams

0 2 4 6 8 10 12 14

-200

0

200

400

600

800

1000

1200

1400

1600

1800

應力 (MPa)

應變()

(a)

0 2 4 6 8 10

-200

0

200

400

600

800

1000

1200

1400

1600

應力

(MPa)

位移 ()

(b)

Fig 3-27 Stress-Strain Diagrams for (a) 3 Round Bar and (b) 5 Round Bar

(Note These curves were formulated using Visual Solutions Inc VisSim Software)

75

Cut-Off Area

(a)

(b)

Fig 3-28 Cut-Off Area of (a) 3 Round Bar and (b) 5 Round Bar

76

The force value (N) was retrieved from the Universal Testing Machine

The Poissonrsquos Ratio (ε) is calculated as

ε =

the values for the Poissonrsquos Ratio are in average around 0297

The Youngrsquos Modulus (E) is calculated as

E =

Where

Stress =

Cross-sectional Area =

where D is the Diameter

The value for D was in average around 1258 mm

The values shown by the computer because there is Slippage phenomena between the Clamp and the

specimen will not be taken into consideration for the elongation strain and Youngrsquos modulus and we will

refer to the values that we have meticulously calculated

77

Chapter 4 AR COATING IN DEPTH

41 Experimentrsquos Purpose and Principles

By means of a vacuum chamber and several other instruments we intend to apply Anti-Reflective

Coating using deposition process to a laser diode and in this way reduce its refraction so as to make it

lose less light in the process of amplification and we can control certain wavelengths we want produced

for certain desired applications in our case we are attempting to re-create a Bose-Einstein Condensate

An optimal BEC apparatus is shown in figure 4-1

Fig 4-1 BEC Apparatus

The main point of this experiment is to build a vacuum chamber system attach all the instrumentation

needed (Vacuum pump deposition meter and voltmeter) and use it to apply AR coating to a laser diode

After we have accomplished the AR coating other team will be in charge of designing the BEC apparatus

and use the results of our research

78

42 Experimentrsquos Equipment

421 Vacuum Chamber

For this research we designed a vacuum chamber whose main body is shown in figure 4-2 Its

dimensions are

Width 240 mm

Length 240 mm

Height 200 mm

Outer Diameter 4 in

Inner Diameter 15 in

Fig 4-2 Vacuum Chamber Main Body

The chamber is made up of 6 pass ways pass way A is the connection with the Laser Deposition

Equipment pass way B is the connection with the Turbo Pump and pass way C is for the connection with

the Deposition Source

A

C

B

79

Pass way C is for the deposition source as mentioned above This is a system where a thermal

resistance is heated by passing a high current through it which heats up a filament boat (made of tungsten)

where the material to be evaporated is place We control the temperature as such that the material will

evaporate and the heat will not cause the filament boat to crack

Because P = Isup2 R (where P is power I is current and R is resistance) to avoid the current to flow

where it is not desired we decided that the material for the Thermocouple shown in figure 4-3 should be

Copper ᴓ 63 mm We choose it that way because Copper has very good heat dissipation characteristics

and the resistance value is low It can reduce the value of the current enough to make the thermocouple to

create heat

Fig 4-3 Thermocouple

To the thermocouple we attach the tungsten filament boat We need to take notice of materials to be

used in this design because when using high current the tungsten filament boar will heat up and so the

material must be able to keep up with the heating potential of tungsten and has a low coefficient of heat

dissipation to avoid the tungsten to fail when heating up and therefore not evaporating Considering all

this we decide to use Stainless Steel

Because this clamp will be assembled inside the chamber after many revisions it was determined it

will have the shape shown in figure 4-4

Fig 4-4 Filament Boat Clamp Design

80

For the tungsten filament boat we bought the product from a distributor The dimensions are

Length 100 mm

Width 10 mm

Height 1 mm

Our thermocouple is 15 in but the pass way C is 4 in so we need to attach a Flange that connects

15in to 4in Because these specifications are quite difficult to achieve by Milling we had to use

electrical wire cutting

For the laser clamping system where the laser that is going to be AR coated will be placed will be

connected to pass way A the assembly is shown in figure 4-5 below

Fig 4-5 Cover Assembly

For this design we used an O-ring instead of a gasket so as to save time The design of the assembly

where the laser will be placed is shown in figure 4-6

Fig 4-6 Upper Cover Inner Assembly

D

E

F

81

Point D is the plate in the assembly where the laser diode will be fixed Because of the easy

processing we decide to use Aluminum and it is screwed to the top cover Point E is the connection for

the Quartz crystal resonator and it is designed in the same as point F in this way the results of the quartz

microbalance system will be more accurate in real time Point F is the final resting place for the laser

diode We use a Thor Labs Base with dimensions of ᴓ 9mm and ᴓ 56mm for two different size laser

diodes It just needs to be plugged in for easy installation

From figure 4-6 we know that the system needs signal system connections and because of the

change in temperature inside the chamber this could affect the functioning of the quartz microbalance so

we also need to install water tubes for cooling This is shown in figure 4-7 below

Fig 4-7 Diagram of Upper Cover Connections

In figure 4-8 we show the Feed through connections and their functions

Fig 4-8 Feed through Diagram

82

1 SQM-160 wire 5 Laser Connection 1 (Vin)

2 SQM-160 (G) 6 Laser Connection 2 (G)

3 K-Type-1 7 Laser Connection 3 (PD)

4 K-Type-2 8 Not In Use

The fully assembled chamber is shown in figure 4-9

Fig 4-9 Fully Assembled Chamber

422 Quartz Crystal Microbalance

For measuring the deposition on our target for coating we used the Inficon SQM-160 RateThickness

Monitor It is an easy to use instrument for measuring many types of thin-film coatings as shown in

figure 4-10

(a) Front Panel (b) Back Panel

Fig 4-10 Inficon SQM-160

83

Table 4-1 shows the technical specifications for this equipment

Number of sensors 2 Standard 4 additional optional

Sensor Frequency Range 40 MHz ~ 60 MHz

Reference Frequency Accuracy 002

Thickness Display Resolution 1 Aring

Thickness Resolution 015 Aring (Std) 0037 Aring (Hi Res)

Density of Stored Films 05-9999 gmcc

Tooling 10-399

Z-Factor 010-1000

Final Thickness 0000-9999k Aring

Measurement Period 15 to 2 sec

Simulation Mode Yes

Frequency Mode Yes

Rate Resolution 011 Arings

Dual Crystal Yes

Etch Mode Yes

Crystal Tooling 10-399

Crystal Fail Min Max 40 to 60 MHz 41 to 61 MHz

Power 100-120 200-240~plusmn10 nominal 20W

Operation Environment 0degC ~ 50degC

0 ~ 80 RH non-condensing

0 ~ 2000 meters

Class 1 Equipment

Pollution Degree 2

Rack Dimensions 885mm x 2127mm x 1969mm

Weight 27 kg

Table 4-1 Inficon SQM-160 RateThickness Monitor Specs

84

To the SQM-160 we need to connect an Oscillator We use the Sigma Instruments Remote Oscillator

Ser No 2 268 as shown in figure 4-11

Fig 4-11 Sigma Instruments Remote Oscillator

The connections diagram is shown in figure 4-12

Fig 4-12 SQM-160 Connections Diagram

85

423 Turbo Pump

For our experiments we used the Pfeiffer TCP 015 Electronic Drive Unit shown below in figure 4-13

Table 4-2 shows the technical specifications for this equipment

(a) Front Panel (b) Back Panel

Fig 4-13 Pfeiffer TCP 015 Electronic Drive

Connection Voltage (100V) 90-112

Mains Frequency 5060 Hz

Start-up Current 22 A

Nominal Frequency 1500 Hz

Rotation Speed 10V = 1500Hz plusmn2

Analog Output Current 10 V = 25 A plusmn 5

Rotation Speed Switchpoint 750 Hz

Works Setting 8 min

Permissible Ambient Temperature 0degC ~ 40degC

Dimensions Front Panel 1285mm x 1063mm

Insertion Length 227mm

Weight 27 Kg

Table 4-2 Pfeiffer TCP 015 Electronic Drive Specs

86

The connections diagram is shown in figure 4-14

Fig 4-14Connections Diagram for Pfeiffer TCP 015

To measure the pressure inside the chamber we use the Granville Phillips 375 Convectron Vacuum

Pressure Controller shown in figure 4-15

(a) Front Panel (b) Back Panel

Fig 4-15 Granville Phillips 375 Convectron

87

Its dimensions are shown in figure 4-16

Fig 4-16 Dimensions of Convectron

Table 4-3 shows the technical specifications for this equipment

Table 4-3 Granville Phillips 375 Convectron Vacuum Pressure Controller Specs

88

424 Multimeter

For our experiment we used the Keithley 2000 Digital Multimeter as shown in figure 4-17

(a) Front Panel (b) Back Panel

Fig 4-17 Keithley Model 2000 6-12-Digit Digital Multimeter

Its technical specifications are shown in table 4-4

Table 4-4 Keithley Model 2000 6-12-Digit Digital Multimeter Specs

89

43 Experiment Procedure

1 Connecting together the equipment and the chamber

(1) We first connect the resonator to the thickness monitor and connect the other side to the

chamber

(2) We now connect the flexible tubes to the turbo pump on one side and to the chamber on the

other

(3) We need to check that tubes are tightly connected to avoid any leaks in the vacuum pumping

process which will not allow us to get to our goal of Torr As shown in figure 4-18

(4) Connect the convectron to the system as shown in figure 4-19

Fig 4-18 checking for leaks using alcohol

Fig 4-19 Convectron attached to System

90

(5) Attach the clamps of the Multimeter to the bottom of the chamber as shown in figure 4-20

(6) Place the Quartz crystal in place

(7) Close tight vacuum chamber

(8) Connect all electrical appliances to power source

Fig 4-20 Multimeter Connections

2 Starting up the System

(1) We turn on all the devices as such Check all systems are ready to function Reset all values

that might be left over from previous tests

(2) Start the thickness monitor and set all values for this experiment In our case we got to testing

the system but not actual coating So we used the simulation mode of the thickness monitor as

shown in figure 4-21

Fig 4-21 Simulation Mode

91

(3) Start the turbo pump Make sure the lid on the vacuum chamber is tightly closed

(4) Start convectron and record initial pressure

(5) Start Multimeter and record initial current

3 Coating Process

(1) If we have the deposition material inside the filament boat the power source for the high

current must be started as well

(2) Record all initial values for thickness current pressure

(3) For an ideal experiment we need a thickness of around 101 nm a pressure of Torr and

a current of 300 A

44 Results

From previous experiments we have shown that we can turn a LED into a laser by means of AR

Coating In figure 4-22 shown below we can compare the actual results of a Diode before and after AR

coating From the blue line we can see that when the diode is at a current of 15mA its light will change

from LED to laser and if we look at the red line its critical current is around 30 to 35 mA

Fig 4-22 AR Coating Comparison for Laser Diodes

This means that the light emitted is not as strong as if the diode had been coated because inside the

chamber there must be some excitation first so the reflectivity of both sides inside the diode must be high

So because of the coating in one of the sides we have opened a door and let the light come out so the

critical current is risen as such and will be higher value than that of before the coating

92

In the following figures we can see the difference between before and after coating in a material The

thickness is around 1016 nm for this material

Fig 4-23 Before Coating

Fig 4-24 After Coating

93

Chapter 5 CONCLUSIONS AND RECOMMENDATIONS

51 Conclusions

For the first part of this independent study taking into consideration the data that came out of our

research and that sent by the provider we can say

1 SUM 23 after heat treatment will unexpectedly develop cracking in the middle of the tensile

testing process and suddenly break

2 Itrsquos possible that in the process of heat treatment to the SUM 23 material the treatment was not

uniform and this will create a pre-loaded moment force on one side that pushes on the other side

of the specimen resulting in material deformation

3 In the process of attaching the strain gauges to the materials it is very easy to make errors due to

poor adhesion or sudden removal in the tensile testing process

For our second part of the independent study the following can be made

1 At the beginning of this independent study we had no idea what Bose-Einstein Condensate was

or what was its purpose After much literature we finally comprehended the basic principles to

put into practice for our research

2 Our systemrsquos basic working principles and equipmentrsquos complexity are a little difficult to grasp

but hopefully we were able to understand enough of it

3 Theoretically from relation between the power and current we can know the advantages and

disadvantages of AR Coating

4 We were able to assemble the system and run test on its functions Even though we were able to

do this there is still much more work left to do with this system

52 Recommendations

For the Tensile Testing the following can be said

1 Ask the provider to check on the process of heat treatment on the SUM 23 material and give

them the information we have gathered through our test so they can correct for the mechanical

properties found if any change is needed

2 To avoid the problem of the inaccuracy of the poor adhesion of strain gauges we can attach

multiple strain gauges to the same one specimen so as to correlate data and improve our results

For the AR Coating the following can be said

1 We need to make sure that there are no physical defects on the main body of the chamber so as to

achieve maximum efficiency in the vacuum process If there was then the vacuum will arrive to

certain point and then start to decrease

2 It would be preferable to add some sort of visual aid that will allow the user to check the inside of

the chamber without actually opening it This will help us determine at what times we should

manipulate the current to better evaporate the substrate

94

REFERENCES

[1] A L Window Strain Gauge Technology Elsevier Applied Science London and New York 2nd

Edition 1992

[2] CC Perry and HR Lissner Strain Gauge Primer McGraw-Hill Book Co Inc New York 1955

[3] James W Dally William F Riley McGraw-Hill 1978

[4] University of Colorado Boulder BEC - What is it and where did the idea come from

httpwwwcoloradoeduphysics2000becwhat_is_ithtml

[5] Ultraslow Light amp Bose-Einstein Condensates Two-way Control with Coherent Light amp Atom

Fields Harvard Hau Lab Dr Lene Vestergaard Hau Optics amp Photonics News 16 1995

[6] The Art of Taming Light Ultra-slow and Stopped Light Harvard Hau Lab Dr Lene

Vestergaard Hau Europhysics News 2004

[7] Nonlinear Optics Shocking Superfluids Harvard Hau Lab Dr Lene Vestergaard Hau Nature

Physics 2007

[8] Model P3 Strain Indicator and Recorder Instruction Manual Vishay Micro-Measurements 2005

[9] Granville-Phillips Series 375 Convectron Vacuum Gauge Controller Instruction Manual Brooks

Automation 2008

[10] Effect of Film Thickness on the Validity of the Sauerbrey Equation for Hydrated Polyelectrolyte

Films Vogt Lin Wu White 2004

[11] Quartz Crystal Microbalance Study of DNA Immobilization and Hybridization for DNA Sensor

Development Chang Zhao 2008

[12] Installation of Strain Gages with SR-4 PrecoatAdhesive Vishay Micro-Measurements 2005

[13] Strain Gauge Measurement ndash A Tutorial National Instruments 1998

[14] Correlation between Vickers Hardness Number and Yield Stress of Cold-Formed Products

Yavuz Tekkaya

[15] httpsenwikipediaorg

Page 20: PC Hinge Materials Testing and AR Laser Diode Coating

20

There are different scales denoted by a single letter that use different loads or different indenters

The result is a dimensionless number denoted as HR X where X will be the letter denoting the scale as

shown below in table 2-1

Table 2-1 Rockwell Hardness Test Scale

Differential depth hardness measurement was first conceived in 1908 by Viennese professor Paul

Ludwik It eliminated the errors associated with the mechanical imperfections of the system such as

backlash and surface imperfections in the specimen Rockwell testing has an advantage over Brinell

testing because the latter was slow itrsquos not useful on fully hardened steel and left too large an impression

to be considered nondestructive

The tester was co-invented by Hugh M Rockwell and Stanley P Rockwell The requirement for this

tester was to quickly determine the effects of heat treatment on steel bearing races

21

223 Vickers Hardness Test HV

This is a type of microindentation hardness test where a diamond indenter of specific geometry is

impressed into the surface of the test specimen using a known applied force ranging from 10 to 1000

grams This type of tests usually has forces of 2N and produce indentations of about 50μm They can be

used to observe changes in hardness on the microscopic scale It is difficult to standardize the

microhardness measurements because it has been found that the microhardness of almost any material is

higher than its macrohardness The values also vary with load and work-hardening effects of materials

The Vickers test is often easier to use than other hardness tests because the required calculations are

independent of the size of the indenter and the indenter can be used for all materials It can be used for all

metals and has one of the widest scales among hardness tests The unit of the Vickers test is denoted as

HV and can be converted to units of Pascal (Pa) but it is not a measurement of pressure The hardness

number is determined by the load over the surface area of the indentation and not the area normal to the

force

A square-based pyramid shaped diamond is use as the indenter It has been established that the ideal

size of a Brinell impression was 38 of the ball diameter As two tangents to the circle at the ends of a

chord 3d8 long intersect at 136plusmn05deg it was decided to use this as the angle of the indenter giving an

angle to the horizontal plane of 22deg on each side The HV number is determined by the ratio FA where F

is the force applied to the diamond in kgf and A is the surface area of the resulting indentation in mmsup2 A

can be determined by the relation

A =

Where A is the surface area of indentation and d is the average length diagonal left by the indenter

This can be approximated as

A =

Then the Vickers Number is

HV =

=

Vickers hardness number is reported as xxxHVyy or xxxHVyyzz (if duration of applied force differs

from 10s to 15s) where xxx are replaced by the hardness number yy is the load in kg and zz indicates

loading time The values are generally independent of test force

The test was developed in 1921 by Robert L Smith and George E Sandland at Vickers Ltd as an

alternative to Brinell method to measure the hardness of materials

22

Fig 2-9 Vickers Indentation Fig 2-10 Vickers Hardness Tester

23 AR Coating

231 Bose-Einstein Condensate

The Bose-Einstein Condensate or BEC is a state of matter of a dilute gas of bosons cooled to

temperatures very near absolute zero around 0K or -27315degC Under such conditions a large fraction of

the bosons occupy the lowest quantum state where the quantum effects become apparent on a

macroscopic scale This gave birth to the Bose-Einstein Statistics which are the rules that govern the

behavior at this state It is one of the two possible ways in which a collection of indistinguishable particles

may occupy a set of available discrete energy states The aggregation of particles in the same state

accounts for the cohesive streaming of laser light and the frictionless creeping of superfluid helium (an

application discussed later) Bose and Einstein recognized that a collection of identical and

indistinguishable particles can be distributed this way This theory applies only to those particles not

limited to single occupancy of the same state particles that do not obey the Pauli Exclusion Principle

restrictions Such particles are the Bosons named after the statistics that correctly describe their behavior

This phenomenon was first predicted by Satyendra Nath Bose around 1924 when he considered how

groups of photons behave He then asked Albert Einstein for help publishing his discoveries to which

Einstein agreed and gave follow up supporting these findings The resulting efforts became the concept of

a Bose gas governed by the Bose-Einstein Statistics described above Einstein demonstrated that cooling

bosonic atoms to a very low temperature would cause them to condense into the lowest accessible

quantum state resulting in a new form of matter

The first gaseous condensate we produced by Eric Cornell and Carl Wieman at the University of

Colorado at Boulder NIST ndash JILA lab sung a gas of rubidium atoms cooled to 170 nK which earned

them the 2001 Nobel Prize in physics together with Wolfgang Ketterle from MIT The transition to BEC

occurs below a critical temperature which for a uniform three dimensional gas consisting of

non-interacting particles with no apparent internal degrees of freedom is given by

23

Tc =

(

)

asymp 33125

Where Tc is the critical temperature n is the particle density m is the mass per boson h is the

reduced Planck constant k is the Boltzmann constant and ζ is the Riemann zeta function

There are two classes of elementary particles defined by whether their quantum spin is a nonnegative

integer or an odd half integer A Bose-Einstein Condensate is shown below in figure 2-11

Fig 2-11 Bose Einstein Condensate at different scales

Bosons are the particles whose quantum spin is a nonnegative integer (s = 0 1 2 etc) Examples of

bosons include fundamental particles (Higgs Boson Photons W and Z Bosons Gluons Gravitons etc)

composite particles (Mesons Hadrons Nuclei and Atoms of Carbon-12 and Helium-4) and

quasi-particles Bosons are considered force carrier particles The Bosons differ from Fermions in that

there is no limit to the number that can occupy the same quantum state This is called the Pauli Exclusion

Principle

The Pauli Exclusion Principle says that no two identical fermions may occupy the same quantum state

simultaneously in other words this means that the total wave function for two identical fermions is

anti-symmetric with respect to exchange of the particles This means that no two electrons in a single

atom can have the same four quantum numbers

Fermion is any particle characterized by Fermi-Dirac Statistics and follows the Pauli Exclusion

Principle described above Quarks Leptons and composite particles (Hadrons Nuclei and Atoms of

Carbon-13 and Helium-3) made of an odd number of these are considered Fermions It can be an

elementary particle such as the electron or a composite particle such as the protons Following the Pauli

24

Exclusion Principle only one fermion can occupy a particular quantum state at any given time If multiple

fermions have the same spatial probability distribution then at least one property of each fermion must be

different Fermions are usually associated with matter because composite fermions are key building

blocks of matter (neutrons and protons)

Fermionsrsquo behavior by the Fermi-Dirac Statistics which describes the energies of single particles in a

system comprising of many identical particles It applies to identical particles with half-odd integer spin

in a system of thermal equilibrium The particles in the system are assumed to have negligible mutual

interaction This allows the many-particle system to be described in terms of single-particle energy states

The result is the Fermi-Dirac distribution of particles over these states and includes the condition that no

two particles can occupy the same state which has considerable effect on the properties of the system

In quantum mechanics the position of an object is uncertain An object has a definite probability of

being at any given point in space This probability is encoded in the wave function mentioned earlier If

one concentrates a large number of identical bosons in a small region then it is possible for their wave

functions to overlap so much that the bosons lose their identity When this happens thatrsquos a Bose-Einstein

Condensate It is only possible at very low temperatures because at high temperatures the individual

bosons have small wave functions and move rapidly which causes them to fly apart

For now applications are still restricted because there are still some setbacks regarding BECs They

are extremely fragile they are being produced in small quantities with just a few million atoms at a time

and finally they can only be made from certain types of atoms Some examples are the atom laser Ketterle

in which a conventional light lase emits a beam of coherent photons this means they are all in phase and

can be concentrated to an extremely small bright spot BECs can slow down light as demonstrated by

Prof Lene Hau PhD in 2001 by the use of a superfluid [7] These manipulations could develop into

new types of telecommunications technology optical storage and quantum computing

BECs are related to super-fluidity and super-conductivity Super-fluidity is the state of matter in

which the behavior is that of a fluid with zero viscosity It was discovered in liquid helium but now it has

applications in astrophysics high-energy physics and theories of quantum gravity

Super-conductivity is a phenomenon of exactly zero electrical resistance and expulsion of magnetic

fields occurring in certain materials when cooled below a characteristic critical temperature A

super-conductor is shown below in figure 2-12

Fig2-12 Super Conductor

25

232 AR Coating Basic Principles

Anti-reflective (AR) coating is a type of optical coating applied to the surface of lenses and other

optical devices (in our case we planned to apply it to a laser diode) to reduce reflection This improves

the efficiency of the system since less light is lost The primary benefit is the elimination of the reflection

itself

When light the medium (glass) it will produce reflection if 100 of the light comes from the air and

enters the glass because therersquos a difference between the index of refraction some of the light will go out

and when the light is coming out of the glass into the air once again because of the difference between

index of refraction some of the light wonrsquot be able to pass through the medium

When the light makes the first trip into the glass there was a loss of about 4 in the reflection and

when the light makes the trip back outside there was another loss of about 4 so when we assume that

100 of the light interacts with the medium actually therersquos just about 92 acting (we neglect the light

absorbed by the glass around 05) To illustrate this idea please refer to figure 2-13

Fig 2-13 Simple Model for Light in Glass Medium

When we apply the AR Coating the light that enters will only have a loss of about 05 and when

making the trip back outside again only 05 of light is loss so we get the result of increasing the light

passing through up to 99 (again neglecting the light absorbed by the glass around 05) To illustrate

this idea please refer to figure 2-14

26

Fig 2-14 Simple Model for Light in Glass Medium after AR Coating

The AR Coating can reduce reflection of incoming light In the case that light hits perpendicular to

the surface of the medium the intensity of the reflection can be calculated using the Reflection

Coefficient

Where n0 and ns are the refractive indices of the first and second media respectively The value of R

varies from 0 (no reflection) to 1 (all light reflected) and is usually quoted as a percentage

Complementary to R is the transmission coefficient or Transmittance If absorption and scattering are

neglected then the value of Transmittance is always 1-R then if a beam of light with intensity I is

incident on the surface a beam of intensity RI is reflected and a beam with intensity TI is transmitted to

the medium

The optimal value is called the Optimal Index of Refraction and is described as

For glass with ns around 15 in air (n0 around 10) then the optimum refractive index will be n1 =

1225

To reduce the refraction in this case we now mean the one that is produced inside the chamber of the

Laser diode the easiest way is to apply a low reflectivity AR coating on the surface of the laser To

measure the appropriate thickness of the coating layer we can use the equations described above By

applying a coat exactly

thickness film we can assure that a certain wavelength is transmitted The

27

reflected waves from the back of the glass medium will be half a wavelength out of phase So they

interfere destructively Because all reflected waves are interfered the maximum amount of light passes

through the coating Please refer to figure 2-15 to illustrate this idea

Fig 2-15 Light Passing through AR Coat and Glass

The most common process to attain this final product is by vacuum deposition For the best coating

results we need to lower the pressure inside the vacuum system to torr

Fig 2-16 Lens without (Top) and With (Bottom) AR Coating

28

233 Laser Diode Basic Principles

A laser diode is a laser whose active medium is a semiconductor similar to that found in

light-emitting diodes (LEDs) Please refer to figure 2-17 The most common type of laser diode is formed

from a p-n junction and powered by injected electric current

Fig 2-17 Laser Diode

Laser diodes are formed by doping a very thin layer on the surface of a crystal wafer The crystal is

doped to produce the n-type region and a p-type region one above the other

By referring to figure 1-2 we can see the basic structure of a working laser When the laser diode has

a current passing through it the light will get excited inside its gain medium and then will start to

resonate this process is called pumping The current exceeds the critical current and then it comes out as

laser light Please refer to figure 1-3 Since we use an external cavity laser we need to apply the AR

coating to the diode and adjust a diffraction grating The laser light comes out the diode and bounces on

the grating making the resonance externally and this becomes the ldquocavityrdquo as shown in figure 2-18

Fig 2-18 Tunable Laser Basic Configuration

29

The most important feature of the external cavity laser is that we can adjust the wavelength easily just

by changing the diffraction gratingrsquos angle and in the end this is the output wavelength of the laser For

different wavelengths there will be different levels of visible light as shown in figure 2-19

Fig 2-19 Light Spectrum

234 Quartz Microbalance System

A Quartz Crystal Microbalance is an instrument that measures a mass per unit area by measuring the

change in frequency of a quartz crystal resonator The resonance is disturbed by the addition or removal

of a small mass due to oxide growthdecay or film deposition (which is the case in our study) at the

surface of the acoustic resonator The QCM can be used under vacuum in gas phase and more recently in

liquid environments It is useful for monitoring the rate of deposition in thin film deposition systems

under vacuum Frequency measurements are easily made with high precision

For our research we used the Sigma Instruments SQM-160 RateThickness Monitor shown in figure

2-20

Fig 2-20 Front and Back Panels of SQM-160

30

The microbalance uses Quartz as the resonator Quartz is one member of the family of crystals that

experience the Piezoelectric Effect

Piezoelectricity is the charge that accumulates in certain solid materials in response to applied

mechanical stress It means electricity resulting from pressure It was discovered in 1880 by Jacques and

Pierre Curie It is understood as the linear electromechanical interaction between the mechanical and the

electrical state in crystalline materials with no inversion symmetry It is a reversible process in that

materials exhibiting direct piezoelectricity also exhibit the reverse This means that the internal generation

of electrical resulting from applied mechanical force and vice versa

By using the piezoelectric effect we can probe as an acoustic resonance by electrical means Applying

alternating current to the quartz crystal induces oscillations This creates a shear wave We can use these

qualities to determine the resonance frequency at high accuracy

The frequency of oscillation of the crystal is partially dependent in the thickness of the crystal During

normal operation all the variables are held constant so a change in thickness correlates directly to a

change in frequency As mass is deposited or etched away the thickness increases or decreases and so the

frequency of oscillation changes accordingly With some simplifying assumptions the frequency change

can be quantified and correlated precisely to the mass change using the Sauerbreyrsquos Equation

Developed by G Sauerbrey in 1959 it is a method for correlating changes in the oscillation

frequency of a piezoelectric crystal with the mass deposited on it It is defined as below

Where f0 is the Resonant frequency Δf is the Frequency change Δm is the mass change A is the

piezoelectrically active area of the crystal q is the Density of quartz (2648 gcmsup3) and μq is the Shear

modulus of quarts(2947x gcmssup2)

Because the film is treated as an extension of thickness Sauerbreyrsquos equation only applies to systems

in which the following 3 conditions are met

Deposited mass must be rigid

Deposited mass must be distributed evenly

The frequency change

lt002

If the change is greater than 2 the Z-match method must be used to determine the change in mass

It is defined as

Where fL is the frequency of the loaded crystal fU is the resonant frequency Nq is the frequency

constant (1668x HzAring) Δm is the mass change A is the piezoelectrically active area of the crystal

31

q is the density of quartz Z is the method constant f is the density of film μq Is the shear modulus of

quarts and μf is the shear modulus of film

The Sauerbrey equation cannot be applied to systems under liquid medium

The crystals are seed crystals plated with gold on both top and bottom for applications A crystal is

shown in figure 2-21 The QCM consists of a thin piezoelectric plate with electrodes evaporated on both

sides Due to the piezoelectric effect AC voltage across the electrodes induces a shear deformation and

vice versa The electromechanical coupling provides a simple way to detect an acoustic resonance by

electrical means

The Z also called Z-factor is a constant value for different materials and it is shown together with the

density of different materials in table 2-2 below

Fig 2-21 QCM Crystals

The Oscillator of the SQM-160 is shown in figure 2-22 and the equivalent circuit for the Resonant

Oscillator is shown in figure 2-23

Fig 2-22 SQM-160 Oscillator

32

Fig 2-23 Oscillator Circuit

33

Table 2-2 Z-Ratios for Different Materials

Table 2-2 Continued

34

Table 2-2 Continued

35

Table 2-2 Continued

36

Table 2-2 Continued

37

Table 2-2 Continued

38

Table 2-2 Continued

235 Vacuum Chamber System

Vacuum Evaporation is the process of depositing thin films of materials onto surfaces The technique

consists of pumping a vacuum chamber to pressures of less than torr and heating a material to

produce a flux of vapor in order to deposit the material onto a surface The material to be vaporized is

typically heated until its vapor pressure is high enough to produce a flux several Angstrom per second by

using an electrically resistive heater or bombardment by a high voltage beam The process was invented

by Henri Nestle in 1886 for food industry

In here the system has been pumped to a vacuum of Torr When a high current is passed

through the filament boat the filament boat is heated over the desired metal evaporation temperature and

so evaporation starts When the evaporation process is finished and the metal cools down crystals

condensate in the surface of the wafer From the weight of the evaporated material the distance between

the filament boat and the wafer we are able to calculate the deposition thickness and we can also use the

mass detector follower like the Quartz crystal resonator microbalance system In the process of

evaporation we usually use a board in between the filament boat and the wafer This is because before we

arrive to the desired evaporation temperature there will be some impurities that will be vaporized in the

controlled environment so we first use a small current and the board in between to get rid of those

impurities and this raises the purity of the deposition material

39

A vacuum evaporation system is shown in figure 2-24

Fig 2-24 Vacuum Evaporation System

Rough Vacuum 760 ~ 1 torr

Medium Vacuum 1 ~ torr

High Vacuum ~ torr

Ultra-High Vacuum Lower than torr

Table 2-3 Classification of Vacuum

For our study we need to use a Turbo Pump A regular turbo pump is shown in figure 2-25

Fig 2-25 Turbo Pump

For our research we used the Pfeiffer TCP 015 Electronic Drive Unit and Granville Phillips 375

Convectron shown below in figure 2-26

40

Fig 2-26 Control and Measurement Equipment

The electronic drive controls the turbo pump and the Convectron measures the pressure inside our

chamber The turbo pump is a type of vacuum pump used to maintain high vacuum Most turbo pumps

are centrifugal When we start the pumping we need to use a mechanical pump so as to decrease the

pressure inside the system from constant atmospheric pressure to torr and then the use dispersion

pump to continue the vacuum until we get to the desired pressure We need to notice though when we

start the dispersion pump we canrsquot turn off the mechanical pump and they both need to run together If

we need to turn off the pumping we first turn off the dispersion pump wait for it to completely stop and

then turn off the mechanical pump

Our completely assembled system is shown in figure 2-27 below

Fig 2-27 Complete System

41

Chapter 3 TENSILE TESTING IN DEPTH

31 Experimentrsquos Purpose and Principles

By means of Universal testing machine and Strain gauges we were able to observe discuss and

analyze the phenomena created when a specimen of certain material is manipulated under an external load

and determine the stress strain and deformation values later we can use the graphing methods of

stress-strain diagram to describe it

The main point of this experiment is that after the tensile specimen is tested use computer analysis

and the actual strain data and after statistical adjustment make the final results report (Tensile testing

experiment is in accordance with ASTM E8)

32 Experimentrsquos Equipment

321 Universal Testing Machine

For the materials testing experiment part of this research we use a Universal Testing Machine as

shown in figure 31 The maximum load it can apply is 100 Ton After the test specimen is secured on the

device with the use of instrumentation the load exerted and the effects of this become apparent on the

specimen and even the smallest of changes can be recorded For our research we used the Chun Yen

Testing Machines Co Ltd 100 Ton Micro Computer Universal Tensile Tester

Fig 31 Universal Testing Machine

42

Table 31 shows the specifications for this machine

Max Capacity 100 Ton

Accuracy plusmn1

Tension (mm) Max Space 1150mm

Grip for Rod 20-70mm

Ram Stroke 250mm

Effective Column Interval 940mm

Crosshead Speed 300mmmin

Testing Speed 0-50mmmin

Volume of Machine 1700times1000times3350mm(LtimesWtimesH)

Volume of Control Panel 1000times800times1500mm(LtimesWtimesH)

Weight 8000kg

Power 3∮220V 20A

Computer AMD K6-2-350

OS Windows XP

Screen 15rdquo CRT

Table 3-1 Chun Yen Testing Machine Specs Table

The connections diagram is shown in figure 3-2

Fig 3-2 Diagram for System Connections

43

When the test specimen is placed when the external force is applied the Load Cell can measure the

size of the applied force and the Encoder measures the expansion rate of change The Local Controller

receives all the information from the 2 units after arranging the results they are displayed in the

computer and they can be afterwards submitted for more complex analysis such as Finite Element

Analysis and we can get the Stress-Strain Diagram

322 Strain Measurement Equipment

The equipment used in our research provides a four-channel measurement that means we can use up

to 4 strain gauges at a time to do our measurements and provides 3 different bridge arrangements as

shown in figure 3-3

(a) (b) (c)

Fig 3-3 Input Connections for Strain Indicator

Figure 3-3 (a) is the Quarter Bridge (b) is the Half Bridge and (c) is the Full Bridge and Transducers

For our study we used the Quarter Bridge and use the Strain Gauge values to decide the position of the

connecting wires The Strain indicator is shown in figure 3-4

Fig 3-4 Vishay Micro-Measurements Model P3 Strain Indicator and Recorder

44

Input Connections Tool Free eccentric lever release

4-channel input

Wire diameter16-28AWG

Bridge Configurations Quarter- Half- and Full Bridge

Bridge Impedance 60-2000Ω

Display 128 64 pixel FSTN positive gray LCD

Data Conversion AD Converter filter

Measurement Range Resolution Strain Range plusmn155mVV

Resolution plusmn00005mVV

Measurement Accuracy plusmn01 of reading plusmn3 counts

Gage Factor Control 0500-9900

Balance Control Software either manual or automatic

Bridge Excitation 15VDC nominal

Communication Interface USB Cable Included

Data Storage Removable Media Card

Shunt Calibration Across bridge completion resistors controlled

by software When Gage Factor=200

120Ω350Ω1000Ω

Analog Output Value 0 to 25V max

Ranges plusmn320 microε plusmn3200 microε plusmn32000 microε

Error 05 output voltage +5mV

Max Error 14 output voltage + 20mV

Update rate 480 samplessec

Output Load 2000Ω

Power Battery Two Alkaline D cells

Battery life 400 hours typ

USB 5V 100mA

Operational Environment Temperature 0-50

Humidity Up to 90 Non-condensing

Case Aluminum Alloy

Size and Weight 228times152times152(mm) 20(kg)

Table 3-2 Vishay Micro-Measurements Model P3 Strain Indicator and Recorder Specs

45

323 Strain Gauge

The strain gaugersquos main basic principle is to use a resistancersquos characteristics to measure the strain

The inside connections of the strain indicator are shown in figure 3-5

Fig 3-5 Inner Connections

As shown above this is a quarter-bridge connection We connect equal-length 3 wires to the 2

connections allowed by the strain gauge wire 1 and 3 can be used to cancel out the effects of temperature

to the resistance and because of the addition of wires 1 and 3 wire 2 can directly measure the experiment

results from the strain gauge and therefore the strain developed with no influence of temperature

If there were no two measuring leads then the relations will be

R 4 =R g +2R L

Where Rg is the Strain Gauge Value and RL is the wire resistance then

4

4

R

R=

Lg

g

RR

R

2

=

gL

gg

RR

RR

21

amp

4

4

R

R=

g

g

R

R(1- L)

Where L is the Signal Loss Factor and so

L =gL

gL

RR

RR

21

2

g

L

R

2R if

g

L

R

2Rltlt1

46

(Actual Value R g =120R L =08g

L

R

2Ris always much smaller than 1)

R 4 =R g +2R LR 2 =R 3 =rR gR 1 =R g 32 RR =0

V 0 =V 2)1( r

r

(

4

4

R

R-

1

1

R

R)

The first term describes loss attenuation effects second term describes loss of balancing capabilities

effects

V 0 =V 2)1( r

r

[

)2

(Lg

g

RR

R

+

T

Lg

g

RR

R

)

2( + T

Lg

L

RR

R

)

2

2( -(

g

g

R

R) T ]

The first term describes loss attenuation effects and loss of balancing capabilities effects the second

third and fourth terms describe the temperature effects on the wire

For the three-wire method we have

L =gL

gL

RR

RR

1

g

L

R

R if

g

L

R

Rltlt1

V 0 =V 2)1( r

r

[

)(Lg

g

RR

R

+

T

Lg

g

RR

R

)( + T

Lg

L

RR

R

)

2( -

T

Lg

g

RR

R

)( - T

Lg

L

RR

R

)

2( ]

V 0 = V2)1( r

r

)(

Lg

g

RR

R

In the last four terms inside parenthesis we can see the effects of temperature being cancelled out and the

effect on first term is not great so this is the reason why in our research we use three wires

47

324 Specimen Measurements

The tensile specimens used in this research are compliant of ASTM E8 Tensile parameters as shown

in figure 3-6

Fig 3-6 Tensile Specimen

Diameter

D(mm)

Gauge

Length

G(mm)

Smallest

Arc

Radius

R(mm)

Shortest

Area

A(mm)

Total

Length

L(mm)

Clamping

Area

Length

B(mm)

Clamping

Area

Diameter

C(mm)

Bar 125 02 625 01 gt10 gt75 ~ 145 ~ 35 20

Table 3-3 Specifications for Round Bar

33 Experiment Procedure

1 Attaching the Strain Gauge to the Tensile Specimen

(1) Prepare 1 ASTM E8 compliant tensile specimen round bar as shown in figure 3-7

(2) Prepare Strain Gauge as those described in table 3-4

(3) Prepare other consumables and adhesive agent such as epoxy adhesive or

cyanoacrylate adhesive as shown in figure 3-8

48

Fig 3-7 Actual Tensile Specimen

Fig 3-8 Other Materials Used (Such as Alcohol gauze transparent tape adhesive)

Gage Type

EA-06-120LZ-120E

Resistance in ohms at 24∘C

1200plusmn03

Gage Factor at 24∘C

2075plusmn05

Transverse Sensitivity at 24∘C

(+07plusmn02)

Table 3-4 Specifications for Strain Gauge

2 Attaching Strain Gauge

As shown in following figures we shall explain the attachment of the strain gauge

(1) Use sand paper and a rasp to clean thoroughly the surface where the strain gauge will be

attached to

49

(a)

(2) Use alcohol to wash the surface where the strain gauge will be attached and use gauze to rub

it off

(b)

(3) Find a clean surface and clean it with alcohol and gauze

(c)

(4) Place the strain gauge in the clean surface Use a piece of transparent tape on top of the strain

gauge after securely placed rip it off the surface carefully

50

(d)

(5) Use a piece of white paper to mark the place where the strain gauge will be attached and in

this way we can make sure that the strain gauge will be placed as horizontally and vertically

correct as possible

(e)

(6) In the place where we had our mark place the strain gauge

(f)

(7) Carefully lift one side of the tape and apply some of the adhesive agent to both the strain

gauge and specimenrsquos surface

(g)

51

(8) We need to make sure that the gauge and the specimen will be firmly attached so we gently

apply pressure with our thumb

(h)

(9) After the adhesive is fully dry we can carefully rip off the tape

(i)

(10) We need to do the whole process twice one for the horizontally placed strain gauge and one

for the vertically placed strain gauge

52

(j)

(11) We now proceed to solder the wires to the strain gauge

(k)

(12) After soldering we use a Volt Multimeter to measure that there is no contact between wires

If there is none then the specimen is ready for testing

(l)

(13) We now need to measure a 5cm distance and mark it to check and compare the elongation

before and after the tensile testing

(m)

53

Fig 3-9 Specimen-Strain Gauge Process

3 Tensile Test

(1) Enter the computer application that controls the tensile testing machine

(2) Turn on the tensile testing machine main switch

(3) Adjust the hydraulic pump to go back to its original position

(4) Bring the lowering motor down to a distance enough so as to attach the tensile specimen to the

system open the clamps and secure the specimen

(a)

(5) Connect all the necessary wires to the strain indicator equipment

54

(b)

(6) Start the ascending motor and wait for the expansion

(c)

Fig 3-10 Specimen-Tensile Testing Process

4 Start the Test

(1) Enter the software application and enter some variables needed for the experiment in the

specific screen

(2) Go back to the main screen and press the [測試] (measure) button to start the test and auto

recording in the software

(3) After the specimen breaks the mechanical device will automatically stop and ask the user to

enter the total displacement We take out the specimen from the testing machine and adjust the

machinersquos position back to its original position

(4) Save the results information

(5) Record the results from the strain indicator

34 Results

From this experiment we can get the Poissonrsquos Ratio Youngrsquos Modulus and Yield Strength etc and

because of the slippage phenomenon in the clamp at the moment of the test then the Elastic Limit will

display some yield phenomena So omit any undesirable results we just take the Yield portion of the

results as reference

In the process of the experiment the most important part to attend to is the attaching of the strain

gauge because the gaugersquos purpose is to measure the strain developed during the test and this strain

might be very small If the gaugersquos angle change during the test ie is not well attached this will affect

the accuracy of the measurements of Poissonrsquos ratio and Youngrsquos modulus

55

The materials provided by the manufacturer are SUM 23 and SUM 43 steel round bars and these two

types of materials have been through different heat treatment processes so they can be sub-divided

further into untreated material heat-treated material and black surface heat treated material for the two

materials with heat treatment the treatment process and finished are different In the end we only have

the mechanical properties that were calculated after our research of these materials

All of the specifications are identical to those shown in figure 3-6

341 SUM 23

Fig 3-11 SUM 23 Untreated Material

Number 7 10

Hardness(HRB) 74 75

Yield Stress (MPa) 448 440

Tensile Strength (MPa) 544 560

Poissonrsquos Ratio 029 027

Youngrsquos Modulus (GPa) 203 210

Cut-off Area Shrinking () 42 41

Elongation () 1125 1011

Table 3-5 Mechanical Properties of SUM 23 Untreated

56

Stress-Strain Diagram

(a)

(b)

57

Fig 3-12 Stress-Strain Diagrams for (a) 7 Round Bar and (b) 10 Round Bar

Cut-Off Area

(a)

(b)

Fig 3-13 Cut-Off Area of (a) 7 Round Bar and (b) 10 Round Bar

58

SUM 23 Nickel Round Bar

Fig 3-14 SUM 23 Nickel Material

Number 1 2 3 4

Hardness(HRB) 48 50 49 48

Yield Stress (MPa) 370 370 380 400

Tensile Strength (MPa) 455 451 450 450

Poissonrsquos Ratio 028 046 029 026

Youngrsquos Modulus (GPa) 243 303 246 206

Cut-off Area Shrinking () 803 803 726 601

Elongation () 566 65 602 647

Table 3-6 Mechanical Properties of SUM 23 Nickel

59

Stress-Strain Diagram

(a)

60

(b)

(c)

(d)

61

Fig 3-15 Stress-Strain Diagrams for (a) 1 Round Bar (b) 2 Round Bar (c) 3 Round Bar and (d)

4 Round Bar

Cut-Off Area

(a)

(b)

62

(c)

(d)

Fig 3-16 Cut-Off Area of (a) 1 Round Bar (b) 2 Round Bar (c) 3 Round Bar and (d) 4 Round

Bar

63

SUM 23 Black Surface Round Bar

Fig 3-17 SUM 23 Black Surface Material

Number 1 2 3

Hardness(HRB) 51 50 51

Yield Stress (MPa) 378 371 369

Tensile Strength (MPa) 467 465 464

Poissonrsquos Ratio 03 016 04

Youngrsquos Modulus (GPa) 215 266 266

Cut-off Area Shrinking () 986 94 848

Elongation () 748 805 761

Table 3-7 Mechanical Properties of SUM 23 Black Surface Material

64

Stress-Strain Diagram

(a)

(b)

65

(c)

Fig 3-18 Stress-Strain Diagrams for (a) 1 Round Bar 2 Round Bar and (c) 3 Round Bar

Cut-Off Surface

(a)

66

(b)

(c)

Fig 3-19 Cut-Off Surface of (a) 1 Round Bar 2 Round Bar and (c) 3 Round Bar

67

342 SUM 43

Fig 3-20 Untreated SUM 43 Untreated Material

Number 1 5

Hardness(HRB) 76 75

Yield Stress (MPa) 572 594

Tensile Strength (MPa) 743 785

Poissonrsquos Ratio 027 029

Youngrsquos Modulus (GPa) 200 202

Cut-off Area Shrinking () 338 2944

Elongation () 857 894

Table 3-8 Mechanical Properties of SUM 43 Untreated

68

Stress-Strain Diagrams

(a)

(b)

Fig 3-21 Stress-Strain Diagrams for SUM 43 (a) 1 Round Bar and (b) 5 Round Bar

69

Cut-Off Area

(a)

(b)

Fig 3-22 Cut-Off Area of SUM 43 (a) 1 Round Bar and (b) 5 Round Bar

70

SUM 43 Nickel Round Bar

Fig 3-23 SUM 43 Nickel Material

Number 4 5

Hardness(HRB) 51 50

Yield Stress (MPa) 1580 1544

Tensile Strength (MPa) 1639 1625

Poissonrsquos Ratio 03 028

Youngrsquos Modulus (GPa) 194 201

Cut-off Area Shrinking () 1697 137

Elongation () 376 265

Table 3-9 Mechanical Properties of SUM 43 Nickel

71

Stress-Strain Diagrams

(a)

(b)

Fig 3-24 Stress-Strain Diagrams for (a) 4 Round Bar and (b) 5 Round Bar

72

Cut-Off Area

(a)

(b)

Fig 3-25 Cut-Off Area of (a) 4 Round Bar and (b) 5 Round Bar

73

SUM 43 Black Surface Material

Fig 3-26 SUM 43 Black Surface Material

Number 3 5

Hardness(HRB) 56 56

Yield Stress (MPa) 1416 1361

Tensile Strength (MPa) 1591 1402

Poissonrsquos Ratio 029 031

Youngrsquos Modulus (GPa) 200 202

Cut-off Area Shrinking () 139 124

Elongation () 24 24

Table 3-10 Mechanical Properties of SUM 43 Black Surface Material

74

Stress-Strain Diagrams

0 2 4 6 8 10 12 14

-200

0

200

400

600

800

1000

1200

1400

1600

1800

應力 (MPa)

應變()

(a)

0 2 4 6 8 10

-200

0

200

400

600

800

1000

1200

1400

1600

應力

(MPa)

位移 ()

(b)

Fig 3-27 Stress-Strain Diagrams for (a) 3 Round Bar and (b) 5 Round Bar

(Note These curves were formulated using Visual Solutions Inc VisSim Software)

75

Cut-Off Area

(a)

(b)

Fig 3-28 Cut-Off Area of (a) 3 Round Bar and (b) 5 Round Bar

76

The force value (N) was retrieved from the Universal Testing Machine

The Poissonrsquos Ratio (ε) is calculated as

ε =

the values for the Poissonrsquos Ratio are in average around 0297

The Youngrsquos Modulus (E) is calculated as

E =

Where

Stress =

Cross-sectional Area =

where D is the Diameter

The value for D was in average around 1258 mm

The values shown by the computer because there is Slippage phenomena between the Clamp and the

specimen will not be taken into consideration for the elongation strain and Youngrsquos modulus and we will

refer to the values that we have meticulously calculated

77

Chapter 4 AR COATING IN DEPTH

41 Experimentrsquos Purpose and Principles

By means of a vacuum chamber and several other instruments we intend to apply Anti-Reflective

Coating using deposition process to a laser diode and in this way reduce its refraction so as to make it

lose less light in the process of amplification and we can control certain wavelengths we want produced

for certain desired applications in our case we are attempting to re-create a Bose-Einstein Condensate

An optimal BEC apparatus is shown in figure 4-1

Fig 4-1 BEC Apparatus

The main point of this experiment is to build a vacuum chamber system attach all the instrumentation

needed (Vacuum pump deposition meter and voltmeter) and use it to apply AR coating to a laser diode

After we have accomplished the AR coating other team will be in charge of designing the BEC apparatus

and use the results of our research

78

42 Experimentrsquos Equipment

421 Vacuum Chamber

For this research we designed a vacuum chamber whose main body is shown in figure 4-2 Its

dimensions are

Width 240 mm

Length 240 mm

Height 200 mm

Outer Diameter 4 in

Inner Diameter 15 in

Fig 4-2 Vacuum Chamber Main Body

The chamber is made up of 6 pass ways pass way A is the connection with the Laser Deposition

Equipment pass way B is the connection with the Turbo Pump and pass way C is for the connection with

the Deposition Source

A

C

B

79

Pass way C is for the deposition source as mentioned above This is a system where a thermal

resistance is heated by passing a high current through it which heats up a filament boat (made of tungsten)

where the material to be evaporated is place We control the temperature as such that the material will

evaporate and the heat will not cause the filament boat to crack

Because P = Isup2 R (where P is power I is current and R is resistance) to avoid the current to flow

where it is not desired we decided that the material for the Thermocouple shown in figure 4-3 should be

Copper ᴓ 63 mm We choose it that way because Copper has very good heat dissipation characteristics

and the resistance value is low It can reduce the value of the current enough to make the thermocouple to

create heat

Fig 4-3 Thermocouple

To the thermocouple we attach the tungsten filament boat We need to take notice of materials to be

used in this design because when using high current the tungsten filament boar will heat up and so the

material must be able to keep up with the heating potential of tungsten and has a low coefficient of heat

dissipation to avoid the tungsten to fail when heating up and therefore not evaporating Considering all

this we decide to use Stainless Steel

Because this clamp will be assembled inside the chamber after many revisions it was determined it

will have the shape shown in figure 4-4

Fig 4-4 Filament Boat Clamp Design

80

For the tungsten filament boat we bought the product from a distributor The dimensions are

Length 100 mm

Width 10 mm

Height 1 mm

Our thermocouple is 15 in but the pass way C is 4 in so we need to attach a Flange that connects

15in to 4in Because these specifications are quite difficult to achieve by Milling we had to use

electrical wire cutting

For the laser clamping system where the laser that is going to be AR coated will be placed will be

connected to pass way A the assembly is shown in figure 4-5 below

Fig 4-5 Cover Assembly

For this design we used an O-ring instead of a gasket so as to save time The design of the assembly

where the laser will be placed is shown in figure 4-6

Fig 4-6 Upper Cover Inner Assembly

D

E

F

81

Point D is the plate in the assembly where the laser diode will be fixed Because of the easy

processing we decide to use Aluminum and it is screwed to the top cover Point E is the connection for

the Quartz crystal resonator and it is designed in the same as point F in this way the results of the quartz

microbalance system will be more accurate in real time Point F is the final resting place for the laser

diode We use a Thor Labs Base with dimensions of ᴓ 9mm and ᴓ 56mm for two different size laser

diodes It just needs to be plugged in for easy installation

From figure 4-6 we know that the system needs signal system connections and because of the

change in temperature inside the chamber this could affect the functioning of the quartz microbalance so

we also need to install water tubes for cooling This is shown in figure 4-7 below

Fig 4-7 Diagram of Upper Cover Connections

In figure 4-8 we show the Feed through connections and their functions

Fig 4-8 Feed through Diagram

82

1 SQM-160 wire 5 Laser Connection 1 (Vin)

2 SQM-160 (G) 6 Laser Connection 2 (G)

3 K-Type-1 7 Laser Connection 3 (PD)

4 K-Type-2 8 Not In Use

The fully assembled chamber is shown in figure 4-9

Fig 4-9 Fully Assembled Chamber

422 Quartz Crystal Microbalance

For measuring the deposition on our target for coating we used the Inficon SQM-160 RateThickness

Monitor It is an easy to use instrument for measuring many types of thin-film coatings as shown in

figure 4-10

(a) Front Panel (b) Back Panel

Fig 4-10 Inficon SQM-160

83

Table 4-1 shows the technical specifications for this equipment

Number of sensors 2 Standard 4 additional optional

Sensor Frequency Range 40 MHz ~ 60 MHz

Reference Frequency Accuracy 002

Thickness Display Resolution 1 Aring

Thickness Resolution 015 Aring (Std) 0037 Aring (Hi Res)

Density of Stored Films 05-9999 gmcc

Tooling 10-399

Z-Factor 010-1000

Final Thickness 0000-9999k Aring

Measurement Period 15 to 2 sec

Simulation Mode Yes

Frequency Mode Yes

Rate Resolution 011 Arings

Dual Crystal Yes

Etch Mode Yes

Crystal Tooling 10-399

Crystal Fail Min Max 40 to 60 MHz 41 to 61 MHz

Power 100-120 200-240~plusmn10 nominal 20W

Operation Environment 0degC ~ 50degC

0 ~ 80 RH non-condensing

0 ~ 2000 meters

Class 1 Equipment

Pollution Degree 2

Rack Dimensions 885mm x 2127mm x 1969mm

Weight 27 kg

Table 4-1 Inficon SQM-160 RateThickness Monitor Specs

84

To the SQM-160 we need to connect an Oscillator We use the Sigma Instruments Remote Oscillator

Ser No 2 268 as shown in figure 4-11

Fig 4-11 Sigma Instruments Remote Oscillator

The connections diagram is shown in figure 4-12

Fig 4-12 SQM-160 Connections Diagram

85

423 Turbo Pump

For our experiments we used the Pfeiffer TCP 015 Electronic Drive Unit shown below in figure 4-13

Table 4-2 shows the technical specifications for this equipment

(a) Front Panel (b) Back Panel

Fig 4-13 Pfeiffer TCP 015 Electronic Drive

Connection Voltage (100V) 90-112

Mains Frequency 5060 Hz

Start-up Current 22 A

Nominal Frequency 1500 Hz

Rotation Speed 10V = 1500Hz plusmn2

Analog Output Current 10 V = 25 A plusmn 5

Rotation Speed Switchpoint 750 Hz

Works Setting 8 min

Permissible Ambient Temperature 0degC ~ 40degC

Dimensions Front Panel 1285mm x 1063mm

Insertion Length 227mm

Weight 27 Kg

Table 4-2 Pfeiffer TCP 015 Electronic Drive Specs

86

The connections diagram is shown in figure 4-14

Fig 4-14Connections Diagram for Pfeiffer TCP 015

To measure the pressure inside the chamber we use the Granville Phillips 375 Convectron Vacuum

Pressure Controller shown in figure 4-15

(a) Front Panel (b) Back Panel

Fig 4-15 Granville Phillips 375 Convectron

87

Its dimensions are shown in figure 4-16

Fig 4-16 Dimensions of Convectron

Table 4-3 shows the technical specifications for this equipment

Table 4-3 Granville Phillips 375 Convectron Vacuum Pressure Controller Specs

88

424 Multimeter

For our experiment we used the Keithley 2000 Digital Multimeter as shown in figure 4-17

(a) Front Panel (b) Back Panel

Fig 4-17 Keithley Model 2000 6-12-Digit Digital Multimeter

Its technical specifications are shown in table 4-4

Table 4-4 Keithley Model 2000 6-12-Digit Digital Multimeter Specs

89

43 Experiment Procedure

1 Connecting together the equipment and the chamber

(1) We first connect the resonator to the thickness monitor and connect the other side to the

chamber

(2) We now connect the flexible tubes to the turbo pump on one side and to the chamber on the

other

(3) We need to check that tubes are tightly connected to avoid any leaks in the vacuum pumping

process which will not allow us to get to our goal of Torr As shown in figure 4-18

(4) Connect the convectron to the system as shown in figure 4-19

Fig 4-18 checking for leaks using alcohol

Fig 4-19 Convectron attached to System

90

(5) Attach the clamps of the Multimeter to the bottom of the chamber as shown in figure 4-20

(6) Place the Quartz crystal in place

(7) Close tight vacuum chamber

(8) Connect all electrical appliances to power source

Fig 4-20 Multimeter Connections

2 Starting up the System

(1) We turn on all the devices as such Check all systems are ready to function Reset all values

that might be left over from previous tests

(2) Start the thickness monitor and set all values for this experiment In our case we got to testing

the system but not actual coating So we used the simulation mode of the thickness monitor as

shown in figure 4-21

Fig 4-21 Simulation Mode

91

(3) Start the turbo pump Make sure the lid on the vacuum chamber is tightly closed

(4) Start convectron and record initial pressure

(5) Start Multimeter and record initial current

3 Coating Process

(1) If we have the deposition material inside the filament boat the power source for the high

current must be started as well

(2) Record all initial values for thickness current pressure

(3) For an ideal experiment we need a thickness of around 101 nm a pressure of Torr and

a current of 300 A

44 Results

From previous experiments we have shown that we can turn a LED into a laser by means of AR

Coating In figure 4-22 shown below we can compare the actual results of a Diode before and after AR

coating From the blue line we can see that when the diode is at a current of 15mA its light will change

from LED to laser and if we look at the red line its critical current is around 30 to 35 mA

Fig 4-22 AR Coating Comparison for Laser Diodes

This means that the light emitted is not as strong as if the diode had been coated because inside the

chamber there must be some excitation first so the reflectivity of both sides inside the diode must be high

So because of the coating in one of the sides we have opened a door and let the light come out so the

critical current is risen as such and will be higher value than that of before the coating

92

In the following figures we can see the difference between before and after coating in a material The

thickness is around 1016 nm for this material

Fig 4-23 Before Coating

Fig 4-24 After Coating

93

Chapter 5 CONCLUSIONS AND RECOMMENDATIONS

51 Conclusions

For the first part of this independent study taking into consideration the data that came out of our

research and that sent by the provider we can say

1 SUM 23 after heat treatment will unexpectedly develop cracking in the middle of the tensile

testing process and suddenly break

2 Itrsquos possible that in the process of heat treatment to the SUM 23 material the treatment was not

uniform and this will create a pre-loaded moment force on one side that pushes on the other side

of the specimen resulting in material deformation

3 In the process of attaching the strain gauges to the materials it is very easy to make errors due to

poor adhesion or sudden removal in the tensile testing process

For our second part of the independent study the following can be made

1 At the beginning of this independent study we had no idea what Bose-Einstein Condensate was

or what was its purpose After much literature we finally comprehended the basic principles to

put into practice for our research

2 Our systemrsquos basic working principles and equipmentrsquos complexity are a little difficult to grasp

but hopefully we were able to understand enough of it

3 Theoretically from relation between the power and current we can know the advantages and

disadvantages of AR Coating

4 We were able to assemble the system and run test on its functions Even though we were able to

do this there is still much more work left to do with this system

52 Recommendations

For the Tensile Testing the following can be said

1 Ask the provider to check on the process of heat treatment on the SUM 23 material and give

them the information we have gathered through our test so they can correct for the mechanical

properties found if any change is needed

2 To avoid the problem of the inaccuracy of the poor adhesion of strain gauges we can attach

multiple strain gauges to the same one specimen so as to correlate data and improve our results

For the AR Coating the following can be said

1 We need to make sure that there are no physical defects on the main body of the chamber so as to

achieve maximum efficiency in the vacuum process If there was then the vacuum will arrive to

certain point and then start to decrease

2 It would be preferable to add some sort of visual aid that will allow the user to check the inside of

the chamber without actually opening it This will help us determine at what times we should

manipulate the current to better evaporate the substrate

94

REFERENCES

[1] A L Window Strain Gauge Technology Elsevier Applied Science London and New York 2nd

Edition 1992

[2] CC Perry and HR Lissner Strain Gauge Primer McGraw-Hill Book Co Inc New York 1955

[3] James W Dally William F Riley McGraw-Hill 1978

[4] University of Colorado Boulder BEC - What is it and where did the idea come from

httpwwwcoloradoeduphysics2000becwhat_is_ithtml

[5] Ultraslow Light amp Bose-Einstein Condensates Two-way Control with Coherent Light amp Atom

Fields Harvard Hau Lab Dr Lene Vestergaard Hau Optics amp Photonics News 16 1995

[6] The Art of Taming Light Ultra-slow and Stopped Light Harvard Hau Lab Dr Lene

Vestergaard Hau Europhysics News 2004

[7] Nonlinear Optics Shocking Superfluids Harvard Hau Lab Dr Lene Vestergaard Hau Nature

Physics 2007

[8] Model P3 Strain Indicator and Recorder Instruction Manual Vishay Micro-Measurements 2005

[9] Granville-Phillips Series 375 Convectron Vacuum Gauge Controller Instruction Manual Brooks

Automation 2008

[10] Effect of Film Thickness on the Validity of the Sauerbrey Equation for Hydrated Polyelectrolyte

Films Vogt Lin Wu White 2004

[11] Quartz Crystal Microbalance Study of DNA Immobilization and Hybridization for DNA Sensor

Development Chang Zhao 2008

[12] Installation of Strain Gages with SR-4 PrecoatAdhesive Vishay Micro-Measurements 2005

[13] Strain Gauge Measurement ndash A Tutorial National Instruments 1998

[14] Correlation between Vickers Hardness Number and Yield Stress of Cold-Formed Products

Yavuz Tekkaya

[15] httpsenwikipediaorg

Page 21: PC Hinge Materials Testing and AR Laser Diode Coating

21

223 Vickers Hardness Test HV

This is a type of microindentation hardness test where a diamond indenter of specific geometry is

impressed into the surface of the test specimen using a known applied force ranging from 10 to 1000

grams This type of tests usually has forces of 2N and produce indentations of about 50μm They can be

used to observe changes in hardness on the microscopic scale It is difficult to standardize the

microhardness measurements because it has been found that the microhardness of almost any material is

higher than its macrohardness The values also vary with load and work-hardening effects of materials

The Vickers test is often easier to use than other hardness tests because the required calculations are

independent of the size of the indenter and the indenter can be used for all materials It can be used for all

metals and has one of the widest scales among hardness tests The unit of the Vickers test is denoted as

HV and can be converted to units of Pascal (Pa) but it is not a measurement of pressure The hardness

number is determined by the load over the surface area of the indentation and not the area normal to the

force

A square-based pyramid shaped diamond is use as the indenter It has been established that the ideal

size of a Brinell impression was 38 of the ball diameter As two tangents to the circle at the ends of a

chord 3d8 long intersect at 136plusmn05deg it was decided to use this as the angle of the indenter giving an

angle to the horizontal plane of 22deg on each side The HV number is determined by the ratio FA where F

is the force applied to the diamond in kgf and A is the surface area of the resulting indentation in mmsup2 A

can be determined by the relation

A =

Where A is the surface area of indentation and d is the average length diagonal left by the indenter

This can be approximated as

A =

Then the Vickers Number is

HV =

=

Vickers hardness number is reported as xxxHVyy or xxxHVyyzz (if duration of applied force differs

from 10s to 15s) where xxx are replaced by the hardness number yy is the load in kg and zz indicates

loading time The values are generally independent of test force

The test was developed in 1921 by Robert L Smith and George E Sandland at Vickers Ltd as an

alternative to Brinell method to measure the hardness of materials

22

Fig 2-9 Vickers Indentation Fig 2-10 Vickers Hardness Tester

23 AR Coating

231 Bose-Einstein Condensate

The Bose-Einstein Condensate or BEC is a state of matter of a dilute gas of bosons cooled to

temperatures very near absolute zero around 0K or -27315degC Under such conditions a large fraction of

the bosons occupy the lowest quantum state where the quantum effects become apparent on a

macroscopic scale This gave birth to the Bose-Einstein Statistics which are the rules that govern the

behavior at this state It is one of the two possible ways in which a collection of indistinguishable particles

may occupy a set of available discrete energy states The aggregation of particles in the same state

accounts for the cohesive streaming of laser light and the frictionless creeping of superfluid helium (an

application discussed later) Bose and Einstein recognized that a collection of identical and

indistinguishable particles can be distributed this way This theory applies only to those particles not

limited to single occupancy of the same state particles that do not obey the Pauli Exclusion Principle

restrictions Such particles are the Bosons named after the statistics that correctly describe their behavior

This phenomenon was first predicted by Satyendra Nath Bose around 1924 when he considered how

groups of photons behave He then asked Albert Einstein for help publishing his discoveries to which

Einstein agreed and gave follow up supporting these findings The resulting efforts became the concept of

a Bose gas governed by the Bose-Einstein Statistics described above Einstein demonstrated that cooling

bosonic atoms to a very low temperature would cause them to condense into the lowest accessible

quantum state resulting in a new form of matter

The first gaseous condensate we produced by Eric Cornell and Carl Wieman at the University of

Colorado at Boulder NIST ndash JILA lab sung a gas of rubidium atoms cooled to 170 nK which earned

them the 2001 Nobel Prize in physics together with Wolfgang Ketterle from MIT The transition to BEC

occurs below a critical temperature which for a uniform three dimensional gas consisting of

non-interacting particles with no apparent internal degrees of freedom is given by

23

Tc =

(

)

asymp 33125

Where Tc is the critical temperature n is the particle density m is the mass per boson h is the

reduced Planck constant k is the Boltzmann constant and ζ is the Riemann zeta function

There are two classes of elementary particles defined by whether their quantum spin is a nonnegative

integer or an odd half integer A Bose-Einstein Condensate is shown below in figure 2-11

Fig 2-11 Bose Einstein Condensate at different scales

Bosons are the particles whose quantum spin is a nonnegative integer (s = 0 1 2 etc) Examples of

bosons include fundamental particles (Higgs Boson Photons W and Z Bosons Gluons Gravitons etc)

composite particles (Mesons Hadrons Nuclei and Atoms of Carbon-12 and Helium-4) and

quasi-particles Bosons are considered force carrier particles The Bosons differ from Fermions in that

there is no limit to the number that can occupy the same quantum state This is called the Pauli Exclusion

Principle

The Pauli Exclusion Principle says that no two identical fermions may occupy the same quantum state

simultaneously in other words this means that the total wave function for two identical fermions is

anti-symmetric with respect to exchange of the particles This means that no two electrons in a single

atom can have the same four quantum numbers

Fermion is any particle characterized by Fermi-Dirac Statistics and follows the Pauli Exclusion

Principle described above Quarks Leptons and composite particles (Hadrons Nuclei and Atoms of

Carbon-13 and Helium-3) made of an odd number of these are considered Fermions It can be an

elementary particle such as the electron or a composite particle such as the protons Following the Pauli

24

Exclusion Principle only one fermion can occupy a particular quantum state at any given time If multiple

fermions have the same spatial probability distribution then at least one property of each fermion must be

different Fermions are usually associated with matter because composite fermions are key building

blocks of matter (neutrons and protons)

Fermionsrsquo behavior by the Fermi-Dirac Statistics which describes the energies of single particles in a

system comprising of many identical particles It applies to identical particles with half-odd integer spin

in a system of thermal equilibrium The particles in the system are assumed to have negligible mutual

interaction This allows the many-particle system to be described in terms of single-particle energy states

The result is the Fermi-Dirac distribution of particles over these states and includes the condition that no

two particles can occupy the same state which has considerable effect on the properties of the system

In quantum mechanics the position of an object is uncertain An object has a definite probability of

being at any given point in space This probability is encoded in the wave function mentioned earlier If

one concentrates a large number of identical bosons in a small region then it is possible for their wave

functions to overlap so much that the bosons lose their identity When this happens thatrsquos a Bose-Einstein

Condensate It is only possible at very low temperatures because at high temperatures the individual

bosons have small wave functions and move rapidly which causes them to fly apart

For now applications are still restricted because there are still some setbacks regarding BECs They

are extremely fragile they are being produced in small quantities with just a few million atoms at a time

and finally they can only be made from certain types of atoms Some examples are the atom laser Ketterle

in which a conventional light lase emits a beam of coherent photons this means they are all in phase and

can be concentrated to an extremely small bright spot BECs can slow down light as demonstrated by

Prof Lene Hau PhD in 2001 by the use of a superfluid [7] These manipulations could develop into

new types of telecommunications technology optical storage and quantum computing

BECs are related to super-fluidity and super-conductivity Super-fluidity is the state of matter in

which the behavior is that of a fluid with zero viscosity It was discovered in liquid helium but now it has

applications in astrophysics high-energy physics and theories of quantum gravity

Super-conductivity is a phenomenon of exactly zero electrical resistance and expulsion of magnetic

fields occurring in certain materials when cooled below a characteristic critical temperature A

super-conductor is shown below in figure 2-12

Fig2-12 Super Conductor

25

232 AR Coating Basic Principles

Anti-reflective (AR) coating is a type of optical coating applied to the surface of lenses and other

optical devices (in our case we planned to apply it to a laser diode) to reduce reflection This improves

the efficiency of the system since less light is lost The primary benefit is the elimination of the reflection

itself

When light the medium (glass) it will produce reflection if 100 of the light comes from the air and

enters the glass because therersquos a difference between the index of refraction some of the light will go out

and when the light is coming out of the glass into the air once again because of the difference between

index of refraction some of the light wonrsquot be able to pass through the medium

When the light makes the first trip into the glass there was a loss of about 4 in the reflection and

when the light makes the trip back outside there was another loss of about 4 so when we assume that

100 of the light interacts with the medium actually therersquos just about 92 acting (we neglect the light

absorbed by the glass around 05) To illustrate this idea please refer to figure 2-13

Fig 2-13 Simple Model for Light in Glass Medium

When we apply the AR Coating the light that enters will only have a loss of about 05 and when

making the trip back outside again only 05 of light is loss so we get the result of increasing the light

passing through up to 99 (again neglecting the light absorbed by the glass around 05) To illustrate

this idea please refer to figure 2-14

26

Fig 2-14 Simple Model for Light in Glass Medium after AR Coating

The AR Coating can reduce reflection of incoming light In the case that light hits perpendicular to

the surface of the medium the intensity of the reflection can be calculated using the Reflection

Coefficient

Where n0 and ns are the refractive indices of the first and second media respectively The value of R

varies from 0 (no reflection) to 1 (all light reflected) and is usually quoted as a percentage

Complementary to R is the transmission coefficient or Transmittance If absorption and scattering are

neglected then the value of Transmittance is always 1-R then if a beam of light with intensity I is

incident on the surface a beam of intensity RI is reflected and a beam with intensity TI is transmitted to

the medium

The optimal value is called the Optimal Index of Refraction and is described as

For glass with ns around 15 in air (n0 around 10) then the optimum refractive index will be n1 =

1225

To reduce the refraction in this case we now mean the one that is produced inside the chamber of the

Laser diode the easiest way is to apply a low reflectivity AR coating on the surface of the laser To

measure the appropriate thickness of the coating layer we can use the equations described above By

applying a coat exactly

thickness film we can assure that a certain wavelength is transmitted The

27

reflected waves from the back of the glass medium will be half a wavelength out of phase So they

interfere destructively Because all reflected waves are interfered the maximum amount of light passes

through the coating Please refer to figure 2-15 to illustrate this idea

Fig 2-15 Light Passing through AR Coat and Glass

The most common process to attain this final product is by vacuum deposition For the best coating

results we need to lower the pressure inside the vacuum system to torr

Fig 2-16 Lens without (Top) and With (Bottom) AR Coating

28

233 Laser Diode Basic Principles

A laser diode is a laser whose active medium is a semiconductor similar to that found in

light-emitting diodes (LEDs) Please refer to figure 2-17 The most common type of laser diode is formed

from a p-n junction and powered by injected electric current

Fig 2-17 Laser Diode

Laser diodes are formed by doping a very thin layer on the surface of a crystal wafer The crystal is

doped to produce the n-type region and a p-type region one above the other

By referring to figure 1-2 we can see the basic structure of a working laser When the laser diode has

a current passing through it the light will get excited inside its gain medium and then will start to

resonate this process is called pumping The current exceeds the critical current and then it comes out as

laser light Please refer to figure 1-3 Since we use an external cavity laser we need to apply the AR

coating to the diode and adjust a diffraction grating The laser light comes out the diode and bounces on

the grating making the resonance externally and this becomes the ldquocavityrdquo as shown in figure 2-18

Fig 2-18 Tunable Laser Basic Configuration

29

The most important feature of the external cavity laser is that we can adjust the wavelength easily just

by changing the diffraction gratingrsquos angle and in the end this is the output wavelength of the laser For

different wavelengths there will be different levels of visible light as shown in figure 2-19

Fig 2-19 Light Spectrum

234 Quartz Microbalance System

A Quartz Crystal Microbalance is an instrument that measures a mass per unit area by measuring the

change in frequency of a quartz crystal resonator The resonance is disturbed by the addition or removal

of a small mass due to oxide growthdecay or film deposition (which is the case in our study) at the

surface of the acoustic resonator The QCM can be used under vacuum in gas phase and more recently in

liquid environments It is useful for monitoring the rate of deposition in thin film deposition systems

under vacuum Frequency measurements are easily made with high precision

For our research we used the Sigma Instruments SQM-160 RateThickness Monitor shown in figure

2-20

Fig 2-20 Front and Back Panels of SQM-160

30

The microbalance uses Quartz as the resonator Quartz is one member of the family of crystals that

experience the Piezoelectric Effect

Piezoelectricity is the charge that accumulates in certain solid materials in response to applied

mechanical stress It means electricity resulting from pressure It was discovered in 1880 by Jacques and

Pierre Curie It is understood as the linear electromechanical interaction between the mechanical and the

electrical state in crystalline materials with no inversion symmetry It is a reversible process in that

materials exhibiting direct piezoelectricity also exhibit the reverse This means that the internal generation

of electrical resulting from applied mechanical force and vice versa

By using the piezoelectric effect we can probe as an acoustic resonance by electrical means Applying

alternating current to the quartz crystal induces oscillations This creates a shear wave We can use these

qualities to determine the resonance frequency at high accuracy

The frequency of oscillation of the crystal is partially dependent in the thickness of the crystal During

normal operation all the variables are held constant so a change in thickness correlates directly to a

change in frequency As mass is deposited or etched away the thickness increases or decreases and so the

frequency of oscillation changes accordingly With some simplifying assumptions the frequency change

can be quantified and correlated precisely to the mass change using the Sauerbreyrsquos Equation

Developed by G Sauerbrey in 1959 it is a method for correlating changes in the oscillation

frequency of a piezoelectric crystal with the mass deposited on it It is defined as below

Where f0 is the Resonant frequency Δf is the Frequency change Δm is the mass change A is the

piezoelectrically active area of the crystal q is the Density of quartz (2648 gcmsup3) and μq is the Shear

modulus of quarts(2947x gcmssup2)

Because the film is treated as an extension of thickness Sauerbreyrsquos equation only applies to systems

in which the following 3 conditions are met

Deposited mass must be rigid

Deposited mass must be distributed evenly

The frequency change

lt002

If the change is greater than 2 the Z-match method must be used to determine the change in mass

It is defined as

Where fL is the frequency of the loaded crystal fU is the resonant frequency Nq is the frequency

constant (1668x HzAring) Δm is the mass change A is the piezoelectrically active area of the crystal

31

q is the density of quartz Z is the method constant f is the density of film μq Is the shear modulus of

quarts and μf is the shear modulus of film

The Sauerbrey equation cannot be applied to systems under liquid medium

The crystals are seed crystals plated with gold on both top and bottom for applications A crystal is

shown in figure 2-21 The QCM consists of a thin piezoelectric plate with electrodes evaporated on both

sides Due to the piezoelectric effect AC voltage across the electrodes induces a shear deformation and

vice versa The electromechanical coupling provides a simple way to detect an acoustic resonance by

electrical means

The Z also called Z-factor is a constant value for different materials and it is shown together with the

density of different materials in table 2-2 below

Fig 2-21 QCM Crystals

The Oscillator of the SQM-160 is shown in figure 2-22 and the equivalent circuit for the Resonant

Oscillator is shown in figure 2-23

Fig 2-22 SQM-160 Oscillator

32

Fig 2-23 Oscillator Circuit

33

Table 2-2 Z-Ratios for Different Materials

Table 2-2 Continued

34

Table 2-2 Continued

35

Table 2-2 Continued

36

Table 2-2 Continued

37

Table 2-2 Continued

38

Table 2-2 Continued

235 Vacuum Chamber System

Vacuum Evaporation is the process of depositing thin films of materials onto surfaces The technique

consists of pumping a vacuum chamber to pressures of less than torr and heating a material to

produce a flux of vapor in order to deposit the material onto a surface The material to be vaporized is

typically heated until its vapor pressure is high enough to produce a flux several Angstrom per second by

using an electrically resistive heater or bombardment by a high voltage beam The process was invented

by Henri Nestle in 1886 for food industry

In here the system has been pumped to a vacuum of Torr When a high current is passed

through the filament boat the filament boat is heated over the desired metal evaporation temperature and

so evaporation starts When the evaporation process is finished and the metal cools down crystals

condensate in the surface of the wafer From the weight of the evaporated material the distance between

the filament boat and the wafer we are able to calculate the deposition thickness and we can also use the

mass detector follower like the Quartz crystal resonator microbalance system In the process of

evaporation we usually use a board in between the filament boat and the wafer This is because before we

arrive to the desired evaporation temperature there will be some impurities that will be vaporized in the

controlled environment so we first use a small current and the board in between to get rid of those

impurities and this raises the purity of the deposition material

39

A vacuum evaporation system is shown in figure 2-24

Fig 2-24 Vacuum Evaporation System

Rough Vacuum 760 ~ 1 torr

Medium Vacuum 1 ~ torr

High Vacuum ~ torr

Ultra-High Vacuum Lower than torr

Table 2-3 Classification of Vacuum

For our study we need to use a Turbo Pump A regular turbo pump is shown in figure 2-25

Fig 2-25 Turbo Pump

For our research we used the Pfeiffer TCP 015 Electronic Drive Unit and Granville Phillips 375

Convectron shown below in figure 2-26

40

Fig 2-26 Control and Measurement Equipment

The electronic drive controls the turbo pump and the Convectron measures the pressure inside our

chamber The turbo pump is a type of vacuum pump used to maintain high vacuum Most turbo pumps

are centrifugal When we start the pumping we need to use a mechanical pump so as to decrease the

pressure inside the system from constant atmospheric pressure to torr and then the use dispersion

pump to continue the vacuum until we get to the desired pressure We need to notice though when we

start the dispersion pump we canrsquot turn off the mechanical pump and they both need to run together If

we need to turn off the pumping we first turn off the dispersion pump wait for it to completely stop and

then turn off the mechanical pump

Our completely assembled system is shown in figure 2-27 below

Fig 2-27 Complete System

41

Chapter 3 TENSILE TESTING IN DEPTH

31 Experimentrsquos Purpose and Principles

By means of Universal testing machine and Strain gauges we were able to observe discuss and

analyze the phenomena created when a specimen of certain material is manipulated under an external load

and determine the stress strain and deformation values later we can use the graphing methods of

stress-strain diagram to describe it

The main point of this experiment is that after the tensile specimen is tested use computer analysis

and the actual strain data and after statistical adjustment make the final results report (Tensile testing

experiment is in accordance with ASTM E8)

32 Experimentrsquos Equipment

321 Universal Testing Machine

For the materials testing experiment part of this research we use a Universal Testing Machine as

shown in figure 31 The maximum load it can apply is 100 Ton After the test specimen is secured on the

device with the use of instrumentation the load exerted and the effects of this become apparent on the

specimen and even the smallest of changes can be recorded For our research we used the Chun Yen

Testing Machines Co Ltd 100 Ton Micro Computer Universal Tensile Tester

Fig 31 Universal Testing Machine

42

Table 31 shows the specifications for this machine

Max Capacity 100 Ton

Accuracy plusmn1

Tension (mm) Max Space 1150mm

Grip for Rod 20-70mm

Ram Stroke 250mm

Effective Column Interval 940mm

Crosshead Speed 300mmmin

Testing Speed 0-50mmmin

Volume of Machine 1700times1000times3350mm(LtimesWtimesH)

Volume of Control Panel 1000times800times1500mm(LtimesWtimesH)

Weight 8000kg

Power 3∮220V 20A

Computer AMD K6-2-350

OS Windows XP

Screen 15rdquo CRT

Table 3-1 Chun Yen Testing Machine Specs Table

The connections diagram is shown in figure 3-2

Fig 3-2 Diagram for System Connections

43

When the test specimen is placed when the external force is applied the Load Cell can measure the

size of the applied force and the Encoder measures the expansion rate of change The Local Controller

receives all the information from the 2 units after arranging the results they are displayed in the

computer and they can be afterwards submitted for more complex analysis such as Finite Element

Analysis and we can get the Stress-Strain Diagram

322 Strain Measurement Equipment

The equipment used in our research provides a four-channel measurement that means we can use up

to 4 strain gauges at a time to do our measurements and provides 3 different bridge arrangements as

shown in figure 3-3

(a) (b) (c)

Fig 3-3 Input Connections for Strain Indicator

Figure 3-3 (a) is the Quarter Bridge (b) is the Half Bridge and (c) is the Full Bridge and Transducers

For our study we used the Quarter Bridge and use the Strain Gauge values to decide the position of the

connecting wires The Strain indicator is shown in figure 3-4

Fig 3-4 Vishay Micro-Measurements Model P3 Strain Indicator and Recorder

44

Input Connections Tool Free eccentric lever release

4-channel input

Wire diameter16-28AWG

Bridge Configurations Quarter- Half- and Full Bridge

Bridge Impedance 60-2000Ω

Display 128 64 pixel FSTN positive gray LCD

Data Conversion AD Converter filter

Measurement Range Resolution Strain Range plusmn155mVV

Resolution plusmn00005mVV

Measurement Accuracy plusmn01 of reading plusmn3 counts

Gage Factor Control 0500-9900

Balance Control Software either manual or automatic

Bridge Excitation 15VDC nominal

Communication Interface USB Cable Included

Data Storage Removable Media Card

Shunt Calibration Across bridge completion resistors controlled

by software When Gage Factor=200

120Ω350Ω1000Ω

Analog Output Value 0 to 25V max

Ranges plusmn320 microε plusmn3200 microε plusmn32000 microε

Error 05 output voltage +5mV

Max Error 14 output voltage + 20mV

Update rate 480 samplessec

Output Load 2000Ω

Power Battery Two Alkaline D cells

Battery life 400 hours typ

USB 5V 100mA

Operational Environment Temperature 0-50

Humidity Up to 90 Non-condensing

Case Aluminum Alloy

Size and Weight 228times152times152(mm) 20(kg)

Table 3-2 Vishay Micro-Measurements Model P3 Strain Indicator and Recorder Specs

45

323 Strain Gauge

The strain gaugersquos main basic principle is to use a resistancersquos characteristics to measure the strain

The inside connections of the strain indicator are shown in figure 3-5

Fig 3-5 Inner Connections

As shown above this is a quarter-bridge connection We connect equal-length 3 wires to the 2

connections allowed by the strain gauge wire 1 and 3 can be used to cancel out the effects of temperature

to the resistance and because of the addition of wires 1 and 3 wire 2 can directly measure the experiment

results from the strain gauge and therefore the strain developed with no influence of temperature

If there were no two measuring leads then the relations will be

R 4 =R g +2R L

Where Rg is the Strain Gauge Value and RL is the wire resistance then

4

4

R

R=

Lg

g

RR

R

2

=

gL

gg

RR

RR

21

amp

4

4

R

R=

g

g

R

R(1- L)

Where L is the Signal Loss Factor and so

L =gL

gL

RR

RR

21

2

g

L

R

2R if

g

L

R

2Rltlt1

46

(Actual Value R g =120R L =08g

L

R

2Ris always much smaller than 1)

R 4 =R g +2R LR 2 =R 3 =rR gR 1 =R g 32 RR =0

V 0 =V 2)1( r

r

(

4

4

R

R-

1

1

R

R)

The first term describes loss attenuation effects second term describes loss of balancing capabilities

effects

V 0 =V 2)1( r

r

[

)2

(Lg

g

RR

R

+

T

Lg

g

RR

R

)

2( + T

Lg

L

RR

R

)

2

2( -(

g

g

R

R) T ]

The first term describes loss attenuation effects and loss of balancing capabilities effects the second

third and fourth terms describe the temperature effects on the wire

For the three-wire method we have

L =gL

gL

RR

RR

1

g

L

R

R if

g

L

R

Rltlt1

V 0 =V 2)1( r

r

[

)(Lg

g

RR

R

+

T

Lg

g

RR

R

)( + T

Lg

L

RR

R

)

2( -

T

Lg

g

RR

R

)( - T

Lg

L

RR

R

)

2( ]

V 0 = V2)1( r

r

)(

Lg

g

RR

R

In the last four terms inside parenthesis we can see the effects of temperature being cancelled out and the

effect on first term is not great so this is the reason why in our research we use three wires

47

324 Specimen Measurements

The tensile specimens used in this research are compliant of ASTM E8 Tensile parameters as shown

in figure 3-6

Fig 3-6 Tensile Specimen

Diameter

D(mm)

Gauge

Length

G(mm)

Smallest

Arc

Radius

R(mm)

Shortest

Area

A(mm)

Total

Length

L(mm)

Clamping

Area

Length

B(mm)

Clamping

Area

Diameter

C(mm)

Bar 125 02 625 01 gt10 gt75 ~ 145 ~ 35 20

Table 3-3 Specifications for Round Bar

33 Experiment Procedure

1 Attaching the Strain Gauge to the Tensile Specimen

(1) Prepare 1 ASTM E8 compliant tensile specimen round bar as shown in figure 3-7

(2) Prepare Strain Gauge as those described in table 3-4

(3) Prepare other consumables and adhesive agent such as epoxy adhesive or

cyanoacrylate adhesive as shown in figure 3-8

48

Fig 3-7 Actual Tensile Specimen

Fig 3-8 Other Materials Used (Such as Alcohol gauze transparent tape adhesive)

Gage Type

EA-06-120LZ-120E

Resistance in ohms at 24∘C

1200plusmn03

Gage Factor at 24∘C

2075plusmn05

Transverse Sensitivity at 24∘C

(+07plusmn02)

Table 3-4 Specifications for Strain Gauge

2 Attaching Strain Gauge

As shown in following figures we shall explain the attachment of the strain gauge

(1) Use sand paper and a rasp to clean thoroughly the surface where the strain gauge will be

attached to

49

(a)

(2) Use alcohol to wash the surface where the strain gauge will be attached and use gauze to rub

it off

(b)

(3) Find a clean surface and clean it with alcohol and gauze

(c)

(4) Place the strain gauge in the clean surface Use a piece of transparent tape on top of the strain

gauge after securely placed rip it off the surface carefully

50

(d)

(5) Use a piece of white paper to mark the place where the strain gauge will be attached and in

this way we can make sure that the strain gauge will be placed as horizontally and vertically

correct as possible

(e)

(6) In the place where we had our mark place the strain gauge

(f)

(7) Carefully lift one side of the tape and apply some of the adhesive agent to both the strain

gauge and specimenrsquos surface

(g)

51

(8) We need to make sure that the gauge and the specimen will be firmly attached so we gently

apply pressure with our thumb

(h)

(9) After the adhesive is fully dry we can carefully rip off the tape

(i)

(10) We need to do the whole process twice one for the horizontally placed strain gauge and one

for the vertically placed strain gauge

52

(j)

(11) We now proceed to solder the wires to the strain gauge

(k)

(12) After soldering we use a Volt Multimeter to measure that there is no contact between wires

If there is none then the specimen is ready for testing

(l)

(13) We now need to measure a 5cm distance and mark it to check and compare the elongation

before and after the tensile testing

(m)

53

Fig 3-9 Specimen-Strain Gauge Process

3 Tensile Test

(1) Enter the computer application that controls the tensile testing machine

(2) Turn on the tensile testing machine main switch

(3) Adjust the hydraulic pump to go back to its original position

(4) Bring the lowering motor down to a distance enough so as to attach the tensile specimen to the

system open the clamps and secure the specimen

(a)

(5) Connect all the necessary wires to the strain indicator equipment

54

(b)

(6) Start the ascending motor and wait for the expansion

(c)

Fig 3-10 Specimen-Tensile Testing Process

4 Start the Test

(1) Enter the software application and enter some variables needed for the experiment in the

specific screen

(2) Go back to the main screen and press the [測試] (measure) button to start the test and auto

recording in the software

(3) After the specimen breaks the mechanical device will automatically stop and ask the user to

enter the total displacement We take out the specimen from the testing machine and adjust the

machinersquos position back to its original position

(4) Save the results information

(5) Record the results from the strain indicator

34 Results

From this experiment we can get the Poissonrsquos Ratio Youngrsquos Modulus and Yield Strength etc and

because of the slippage phenomenon in the clamp at the moment of the test then the Elastic Limit will

display some yield phenomena So omit any undesirable results we just take the Yield portion of the

results as reference

In the process of the experiment the most important part to attend to is the attaching of the strain

gauge because the gaugersquos purpose is to measure the strain developed during the test and this strain

might be very small If the gaugersquos angle change during the test ie is not well attached this will affect

the accuracy of the measurements of Poissonrsquos ratio and Youngrsquos modulus

55

The materials provided by the manufacturer are SUM 23 and SUM 43 steel round bars and these two

types of materials have been through different heat treatment processes so they can be sub-divided

further into untreated material heat-treated material and black surface heat treated material for the two

materials with heat treatment the treatment process and finished are different In the end we only have

the mechanical properties that were calculated after our research of these materials

All of the specifications are identical to those shown in figure 3-6

341 SUM 23

Fig 3-11 SUM 23 Untreated Material

Number 7 10

Hardness(HRB) 74 75

Yield Stress (MPa) 448 440

Tensile Strength (MPa) 544 560

Poissonrsquos Ratio 029 027

Youngrsquos Modulus (GPa) 203 210

Cut-off Area Shrinking () 42 41

Elongation () 1125 1011

Table 3-5 Mechanical Properties of SUM 23 Untreated

56

Stress-Strain Diagram

(a)

(b)

57

Fig 3-12 Stress-Strain Diagrams for (a) 7 Round Bar and (b) 10 Round Bar

Cut-Off Area

(a)

(b)

Fig 3-13 Cut-Off Area of (a) 7 Round Bar and (b) 10 Round Bar

58

SUM 23 Nickel Round Bar

Fig 3-14 SUM 23 Nickel Material

Number 1 2 3 4

Hardness(HRB) 48 50 49 48

Yield Stress (MPa) 370 370 380 400

Tensile Strength (MPa) 455 451 450 450

Poissonrsquos Ratio 028 046 029 026

Youngrsquos Modulus (GPa) 243 303 246 206

Cut-off Area Shrinking () 803 803 726 601

Elongation () 566 65 602 647

Table 3-6 Mechanical Properties of SUM 23 Nickel

59

Stress-Strain Diagram

(a)

60

(b)

(c)

(d)

61

Fig 3-15 Stress-Strain Diagrams for (a) 1 Round Bar (b) 2 Round Bar (c) 3 Round Bar and (d)

4 Round Bar

Cut-Off Area

(a)

(b)

62

(c)

(d)

Fig 3-16 Cut-Off Area of (a) 1 Round Bar (b) 2 Round Bar (c) 3 Round Bar and (d) 4 Round

Bar

63

SUM 23 Black Surface Round Bar

Fig 3-17 SUM 23 Black Surface Material

Number 1 2 3

Hardness(HRB) 51 50 51

Yield Stress (MPa) 378 371 369

Tensile Strength (MPa) 467 465 464

Poissonrsquos Ratio 03 016 04

Youngrsquos Modulus (GPa) 215 266 266

Cut-off Area Shrinking () 986 94 848

Elongation () 748 805 761

Table 3-7 Mechanical Properties of SUM 23 Black Surface Material

64

Stress-Strain Diagram

(a)

(b)

65

(c)

Fig 3-18 Stress-Strain Diagrams for (a) 1 Round Bar 2 Round Bar and (c) 3 Round Bar

Cut-Off Surface

(a)

66

(b)

(c)

Fig 3-19 Cut-Off Surface of (a) 1 Round Bar 2 Round Bar and (c) 3 Round Bar

67

342 SUM 43

Fig 3-20 Untreated SUM 43 Untreated Material

Number 1 5

Hardness(HRB) 76 75

Yield Stress (MPa) 572 594

Tensile Strength (MPa) 743 785

Poissonrsquos Ratio 027 029

Youngrsquos Modulus (GPa) 200 202

Cut-off Area Shrinking () 338 2944

Elongation () 857 894

Table 3-8 Mechanical Properties of SUM 43 Untreated

68

Stress-Strain Diagrams

(a)

(b)

Fig 3-21 Stress-Strain Diagrams for SUM 43 (a) 1 Round Bar and (b) 5 Round Bar

69

Cut-Off Area

(a)

(b)

Fig 3-22 Cut-Off Area of SUM 43 (a) 1 Round Bar and (b) 5 Round Bar

70

SUM 43 Nickel Round Bar

Fig 3-23 SUM 43 Nickel Material

Number 4 5

Hardness(HRB) 51 50

Yield Stress (MPa) 1580 1544

Tensile Strength (MPa) 1639 1625

Poissonrsquos Ratio 03 028

Youngrsquos Modulus (GPa) 194 201

Cut-off Area Shrinking () 1697 137

Elongation () 376 265

Table 3-9 Mechanical Properties of SUM 43 Nickel

71

Stress-Strain Diagrams

(a)

(b)

Fig 3-24 Stress-Strain Diagrams for (a) 4 Round Bar and (b) 5 Round Bar

72

Cut-Off Area

(a)

(b)

Fig 3-25 Cut-Off Area of (a) 4 Round Bar and (b) 5 Round Bar

73

SUM 43 Black Surface Material

Fig 3-26 SUM 43 Black Surface Material

Number 3 5

Hardness(HRB) 56 56

Yield Stress (MPa) 1416 1361

Tensile Strength (MPa) 1591 1402

Poissonrsquos Ratio 029 031

Youngrsquos Modulus (GPa) 200 202

Cut-off Area Shrinking () 139 124

Elongation () 24 24

Table 3-10 Mechanical Properties of SUM 43 Black Surface Material

74

Stress-Strain Diagrams

0 2 4 6 8 10 12 14

-200

0

200

400

600

800

1000

1200

1400

1600

1800

應力 (MPa)

應變()

(a)

0 2 4 6 8 10

-200

0

200

400

600

800

1000

1200

1400

1600

應力

(MPa)

位移 ()

(b)

Fig 3-27 Stress-Strain Diagrams for (a) 3 Round Bar and (b) 5 Round Bar

(Note These curves were formulated using Visual Solutions Inc VisSim Software)

75

Cut-Off Area

(a)

(b)

Fig 3-28 Cut-Off Area of (a) 3 Round Bar and (b) 5 Round Bar

76

The force value (N) was retrieved from the Universal Testing Machine

The Poissonrsquos Ratio (ε) is calculated as

ε =

the values for the Poissonrsquos Ratio are in average around 0297

The Youngrsquos Modulus (E) is calculated as

E =

Where

Stress =

Cross-sectional Area =

where D is the Diameter

The value for D was in average around 1258 mm

The values shown by the computer because there is Slippage phenomena between the Clamp and the

specimen will not be taken into consideration for the elongation strain and Youngrsquos modulus and we will

refer to the values that we have meticulously calculated

77

Chapter 4 AR COATING IN DEPTH

41 Experimentrsquos Purpose and Principles

By means of a vacuum chamber and several other instruments we intend to apply Anti-Reflective

Coating using deposition process to a laser diode and in this way reduce its refraction so as to make it

lose less light in the process of amplification and we can control certain wavelengths we want produced

for certain desired applications in our case we are attempting to re-create a Bose-Einstein Condensate

An optimal BEC apparatus is shown in figure 4-1

Fig 4-1 BEC Apparatus

The main point of this experiment is to build a vacuum chamber system attach all the instrumentation

needed (Vacuum pump deposition meter and voltmeter) and use it to apply AR coating to a laser diode

After we have accomplished the AR coating other team will be in charge of designing the BEC apparatus

and use the results of our research

78

42 Experimentrsquos Equipment

421 Vacuum Chamber

For this research we designed a vacuum chamber whose main body is shown in figure 4-2 Its

dimensions are

Width 240 mm

Length 240 mm

Height 200 mm

Outer Diameter 4 in

Inner Diameter 15 in

Fig 4-2 Vacuum Chamber Main Body

The chamber is made up of 6 pass ways pass way A is the connection with the Laser Deposition

Equipment pass way B is the connection with the Turbo Pump and pass way C is for the connection with

the Deposition Source

A

C

B

79

Pass way C is for the deposition source as mentioned above This is a system where a thermal

resistance is heated by passing a high current through it which heats up a filament boat (made of tungsten)

where the material to be evaporated is place We control the temperature as such that the material will

evaporate and the heat will not cause the filament boat to crack

Because P = Isup2 R (where P is power I is current and R is resistance) to avoid the current to flow

where it is not desired we decided that the material for the Thermocouple shown in figure 4-3 should be

Copper ᴓ 63 mm We choose it that way because Copper has very good heat dissipation characteristics

and the resistance value is low It can reduce the value of the current enough to make the thermocouple to

create heat

Fig 4-3 Thermocouple

To the thermocouple we attach the tungsten filament boat We need to take notice of materials to be

used in this design because when using high current the tungsten filament boar will heat up and so the

material must be able to keep up with the heating potential of tungsten and has a low coefficient of heat

dissipation to avoid the tungsten to fail when heating up and therefore not evaporating Considering all

this we decide to use Stainless Steel

Because this clamp will be assembled inside the chamber after many revisions it was determined it

will have the shape shown in figure 4-4

Fig 4-4 Filament Boat Clamp Design

80

For the tungsten filament boat we bought the product from a distributor The dimensions are

Length 100 mm

Width 10 mm

Height 1 mm

Our thermocouple is 15 in but the pass way C is 4 in so we need to attach a Flange that connects

15in to 4in Because these specifications are quite difficult to achieve by Milling we had to use

electrical wire cutting

For the laser clamping system where the laser that is going to be AR coated will be placed will be

connected to pass way A the assembly is shown in figure 4-5 below

Fig 4-5 Cover Assembly

For this design we used an O-ring instead of a gasket so as to save time The design of the assembly

where the laser will be placed is shown in figure 4-6

Fig 4-6 Upper Cover Inner Assembly

D

E

F

81

Point D is the plate in the assembly where the laser diode will be fixed Because of the easy

processing we decide to use Aluminum and it is screwed to the top cover Point E is the connection for

the Quartz crystal resonator and it is designed in the same as point F in this way the results of the quartz

microbalance system will be more accurate in real time Point F is the final resting place for the laser

diode We use a Thor Labs Base with dimensions of ᴓ 9mm and ᴓ 56mm for two different size laser

diodes It just needs to be plugged in for easy installation

From figure 4-6 we know that the system needs signal system connections and because of the

change in temperature inside the chamber this could affect the functioning of the quartz microbalance so

we also need to install water tubes for cooling This is shown in figure 4-7 below

Fig 4-7 Diagram of Upper Cover Connections

In figure 4-8 we show the Feed through connections and their functions

Fig 4-8 Feed through Diagram

82

1 SQM-160 wire 5 Laser Connection 1 (Vin)

2 SQM-160 (G) 6 Laser Connection 2 (G)

3 K-Type-1 7 Laser Connection 3 (PD)

4 K-Type-2 8 Not In Use

The fully assembled chamber is shown in figure 4-9

Fig 4-9 Fully Assembled Chamber

422 Quartz Crystal Microbalance

For measuring the deposition on our target for coating we used the Inficon SQM-160 RateThickness

Monitor It is an easy to use instrument for measuring many types of thin-film coatings as shown in

figure 4-10

(a) Front Panel (b) Back Panel

Fig 4-10 Inficon SQM-160

83

Table 4-1 shows the technical specifications for this equipment

Number of sensors 2 Standard 4 additional optional

Sensor Frequency Range 40 MHz ~ 60 MHz

Reference Frequency Accuracy 002

Thickness Display Resolution 1 Aring

Thickness Resolution 015 Aring (Std) 0037 Aring (Hi Res)

Density of Stored Films 05-9999 gmcc

Tooling 10-399

Z-Factor 010-1000

Final Thickness 0000-9999k Aring

Measurement Period 15 to 2 sec

Simulation Mode Yes

Frequency Mode Yes

Rate Resolution 011 Arings

Dual Crystal Yes

Etch Mode Yes

Crystal Tooling 10-399

Crystal Fail Min Max 40 to 60 MHz 41 to 61 MHz

Power 100-120 200-240~plusmn10 nominal 20W

Operation Environment 0degC ~ 50degC

0 ~ 80 RH non-condensing

0 ~ 2000 meters

Class 1 Equipment

Pollution Degree 2

Rack Dimensions 885mm x 2127mm x 1969mm

Weight 27 kg

Table 4-1 Inficon SQM-160 RateThickness Monitor Specs

84

To the SQM-160 we need to connect an Oscillator We use the Sigma Instruments Remote Oscillator

Ser No 2 268 as shown in figure 4-11

Fig 4-11 Sigma Instruments Remote Oscillator

The connections diagram is shown in figure 4-12

Fig 4-12 SQM-160 Connections Diagram

85

423 Turbo Pump

For our experiments we used the Pfeiffer TCP 015 Electronic Drive Unit shown below in figure 4-13

Table 4-2 shows the technical specifications for this equipment

(a) Front Panel (b) Back Panel

Fig 4-13 Pfeiffer TCP 015 Electronic Drive

Connection Voltage (100V) 90-112

Mains Frequency 5060 Hz

Start-up Current 22 A

Nominal Frequency 1500 Hz

Rotation Speed 10V = 1500Hz plusmn2

Analog Output Current 10 V = 25 A plusmn 5

Rotation Speed Switchpoint 750 Hz

Works Setting 8 min

Permissible Ambient Temperature 0degC ~ 40degC

Dimensions Front Panel 1285mm x 1063mm

Insertion Length 227mm

Weight 27 Kg

Table 4-2 Pfeiffer TCP 015 Electronic Drive Specs

86

The connections diagram is shown in figure 4-14

Fig 4-14Connections Diagram for Pfeiffer TCP 015

To measure the pressure inside the chamber we use the Granville Phillips 375 Convectron Vacuum

Pressure Controller shown in figure 4-15

(a) Front Panel (b) Back Panel

Fig 4-15 Granville Phillips 375 Convectron

87

Its dimensions are shown in figure 4-16

Fig 4-16 Dimensions of Convectron

Table 4-3 shows the technical specifications for this equipment

Table 4-3 Granville Phillips 375 Convectron Vacuum Pressure Controller Specs

88

424 Multimeter

For our experiment we used the Keithley 2000 Digital Multimeter as shown in figure 4-17

(a) Front Panel (b) Back Panel

Fig 4-17 Keithley Model 2000 6-12-Digit Digital Multimeter

Its technical specifications are shown in table 4-4

Table 4-4 Keithley Model 2000 6-12-Digit Digital Multimeter Specs

89

43 Experiment Procedure

1 Connecting together the equipment and the chamber

(1) We first connect the resonator to the thickness monitor and connect the other side to the

chamber

(2) We now connect the flexible tubes to the turbo pump on one side and to the chamber on the

other

(3) We need to check that tubes are tightly connected to avoid any leaks in the vacuum pumping

process which will not allow us to get to our goal of Torr As shown in figure 4-18

(4) Connect the convectron to the system as shown in figure 4-19

Fig 4-18 checking for leaks using alcohol

Fig 4-19 Convectron attached to System

90

(5) Attach the clamps of the Multimeter to the bottom of the chamber as shown in figure 4-20

(6) Place the Quartz crystal in place

(7) Close tight vacuum chamber

(8) Connect all electrical appliances to power source

Fig 4-20 Multimeter Connections

2 Starting up the System

(1) We turn on all the devices as such Check all systems are ready to function Reset all values

that might be left over from previous tests

(2) Start the thickness monitor and set all values for this experiment In our case we got to testing

the system but not actual coating So we used the simulation mode of the thickness monitor as

shown in figure 4-21

Fig 4-21 Simulation Mode

91

(3) Start the turbo pump Make sure the lid on the vacuum chamber is tightly closed

(4) Start convectron and record initial pressure

(5) Start Multimeter and record initial current

3 Coating Process

(1) If we have the deposition material inside the filament boat the power source for the high

current must be started as well

(2) Record all initial values for thickness current pressure

(3) For an ideal experiment we need a thickness of around 101 nm a pressure of Torr and

a current of 300 A

44 Results

From previous experiments we have shown that we can turn a LED into a laser by means of AR

Coating In figure 4-22 shown below we can compare the actual results of a Diode before and after AR

coating From the blue line we can see that when the diode is at a current of 15mA its light will change

from LED to laser and if we look at the red line its critical current is around 30 to 35 mA

Fig 4-22 AR Coating Comparison for Laser Diodes

This means that the light emitted is not as strong as if the diode had been coated because inside the

chamber there must be some excitation first so the reflectivity of both sides inside the diode must be high

So because of the coating in one of the sides we have opened a door and let the light come out so the

critical current is risen as such and will be higher value than that of before the coating

92

In the following figures we can see the difference between before and after coating in a material The

thickness is around 1016 nm for this material

Fig 4-23 Before Coating

Fig 4-24 After Coating

93

Chapter 5 CONCLUSIONS AND RECOMMENDATIONS

51 Conclusions

For the first part of this independent study taking into consideration the data that came out of our

research and that sent by the provider we can say

1 SUM 23 after heat treatment will unexpectedly develop cracking in the middle of the tensile

testing process and suddenly break

2 Itrsquos possible that in the process of heat treatment to the SUM 23 material the treatment was not

uniform and this will create a pre-loaded moment force on one side that pushes on the other side

of the specimen resulting in material deformation

3 In the process of attaching the strain gauges to the materials it is very easy to make errors due to

poor adhesion or sudden removal in the tensile testing process

For our second part of the independent study the following can be made

1 At the beginning of this independent study we had no idea what Bose-Einstein Condensate was

or what was its purpose After much literature we finally comprehended the basic principles to

put into practice for our research

2 Our systemrsquos basic working principles and equipmentrsquos complexity are a little difficult to grasp

but hopefully we were able to understand enough of it

3 Theoretically from relation between the power and current we can know the advantages and

disadvantages of AR Coating

4 We were able to assemble the system and run test on its functions Even though we were able to

do this there is still much more work left to do with this system

52 Recommendations

For the Tensile Testing the following can be said

1 Ask the provider to check on the process of heat treatment on the SUM 23 material and give

them the information we have gathered through our test so they can correct for the mechanical

properties found if any change is needed

2 To avoid the problem of the inaccuracy of the poor adhesion of strain gauges we can attach

multiple strain gauges to the same one specimen so as to correlate data and improve our results

For the AR Coating the following can be said

1 We need to make sure that there are no physical defects on the main body of the chamber so as to

achieve maximum efficiency in the vacuum process If there was then the vacuum will arrive to

certain point and then start to decrease

2 It would be preferable to add some sort of visual aid that will allow the user to check the inside of

the chamber without actually opening it This will help us determine at what times we should

manipulate the current to better evaporate the substrate

94

REFERENCES

[1] A L Window Strain Gauge Technology Elsevier Applied Science London and New York 2nd

Edition 1992

[2] CC Perry and HR Lissner Strain Gauge Primer McGraw-Hill Book Co Inc New York 1955

[3] James W Dally William F Riley McGraw-Hill 1978

[4] University of Colorado Boulder BEC - What is it and where did the idea come from

httpwwwcoloradoeduphysics2000becwhat_is_ithtml

[5] Ultraslow Light amp Bose-Einstein Condensates Two-way Control with Coherent Light amp Atom

Fields Harvard Hau Lab Dr Lene Vestergaard Hau Optics amp Photonics News 16 1995

[6] The Art of Taming Light Ultra-slow and Stopped Light Harvard Hau Lab Dr Lene

Vestergaard Hau Europhysics News 2004

[7] Nonlinear Optics Shocking Superfluids Harvard Hau Lab Dr Lene Vestergaard Hau Nature

Physics 2007

[8] Model P3 Strain Indicator and Recorder Instruction Manual Vishay Micro-Measurements 2005

[9] Granville-Phillips Series 375 Convectron Vacuum Gauge Controller Instruction Manual Brooks

Automation 2008

[10] Effect of Film Thickness on the Validity of the Sauerbrey Equation for Hydrated Polyelectrolyte

Films Vogt Lin Wu White 2004

[11] Quartz Crystal Microbalance Study of DNA Immobilization and Hybridization for DNA Sensor

Development Chang Zhao 2008

[12] Installation of Strain Gages with SR-4 PrecoatAdhesive Vishay Micro-Measurements 2005

[13] Strain Gauge Measurement ndash A Tutorial National Instruments 1998

[14] Correlation between Vickers Hardness Number and Yield Stress of Cold-Formed Products

Yavuz Tekkaya

[15] httpsenwikipediaorg

Page 22: PC Hinge Materials Testing and AR Laser Diode Coating

22

Fig 2-9 Vickers Indentation Fig 2-10 Vickers Hardness Tester

23 AR Coating

231 Bose-Einstein Condensate

The Bose-Einstein Condensate or BEC is a state of matter of a dilute gas of bosons cooled to

temperatures very near absolute zero around 0K or -27315degC Under such conditions a large fraction of

the bosons occupy the lowest quantum state where the quantum effects become apparent on a

macroscopic scale This gave birth to the Bose-Einstein Statistics which are the rules that govern the

behavior at this state It is one of the two possible ways in which a collection of indistinguishable particles

may occupy a set of available discrete energy states The aggregation of particles in the same state

accounts for the cohesive streaming of laser light and the frictionless creeping of superfluid helium (an

application discussed later) Bose and Einstein recognized that a collection of identical and

indistinguishable particles can be distributed this way This theory applies only to those particles not

limited to single occupancy of the same state particles that do not obey the Pauli Exclusion Principle

restrictions Such particles are the Bosons named after the statistics that correctly describe their behavior

This phenomenon was first predicted by Satyendra Nath Bose around 1924 when he considered how

groups of photons behave He then asked Albert Einstein for help publishing his discoveries to which

Einstein agreed and gave follow up supporting these findings The resulting efforts became the concept of

a Bose gas governed by the Bose-Einstein Statistics described above Einstein demonstrated that cooling

bosonic atoms to a very low temperature would cause them to condense into the lowest accessible

quantum state resulting in a new form of matter

The first gaseous condensate we produced by Eric Cornell and Carl Wieman at the University of

Colorado at Boulder NIST ndash JILA lab sung a gas of rubidium atoms cooled to 170 nK which earned

them the 2001 Nobel Prize in physics together with Wolfgang Ketterle from MIT The transition to BEC

occurs below a critical temperature which for a uniform three dimensional gas consisting of

non-interacting particles with no apparent internal degrees of freedom is given by

23

Tc =

(

)

asymp 33125

Where Tc is the critical temperature n is the particle density m is the mass per boson h is the

reduced Planck constant k is the Boltzmann constant and ζ is the Riemann zeta function

There are two classes of elementary particles defined by whether their quantum spin is a nonnegative

integer or an odd half integer A Bose-Einstein Condensate is shown below in figure 2-11

Fig 2-11 Bose Einstein Condensate at different scales

Bosons are the particles whose quantum spin is a nonnegative integer (s = 0 1 2 etc) Examples of

bosons include fundamental particles (Higgs Boson Photons W and Z Bosons Gluons Gravitons etc)

composite particles (Mesons Hadrons Nuclei and Atoms of Carbon-12 and Helium-4) and

quasi-particles Bosons are considered force carrier particles The Bosons differ from Fermions in that

there is no limit to the number that can occupy the same quantum state This is called the Pauli Exclusion

Principle

The Pauli Exclusion Principle says that no two identical fermions may occupy the same quantum state

simultaneously in other words this means that the total wave function for two identical fermions is

anti-symmetric with respect to exchange of the particles This means that no two electrons in a single

atom can have the same four quantum numbers

Fermion is any particle characterized by Fermi-Dirac Statistics and follows the Pauli Exclusion

Principle described above Quarks Leptons and composite particles (Hadrons Nuclei and Atoms of

Carbon-13 and Helium-3) made of an odd number of these are considered Fermions It can be an

elementary particle such as the electron or a composite particle such as the protons Following the Pauli

24

Exclusion Principle only one fermion can occupy a particular quantum state at any given time If multiple

fermions have the same spatial probability distribution then at least one property of each fermion must be

different Fermions are usually associated with matter because composite fermions are key building

blocks of matter (neutrons and protons)

Fermionsrsquo behavior by the Fermi-Dirac Statistics which describes the energies of single particles in a

system comprising of many identical particles It applies to identical particles with half-odd integer spin

in a system of thermal equilibrium The particles in the system are assumed to have negligible mutual

interaction This allows the many-particle system to be described in terms of single-particle energy states

The result is the Fermi-Dirac distribution of particles over these states and includes the condition that no

two particles can occupy the same state which has considerable effect on the properties of the system

In quantum mechanics the position of an object is uncertain An object has a definite probability of

being at any given point in space This probability is encoded in the wave function mentioned earlier If

one concentrates a large number of identical bosons in a small region then it is possible for their wave

functions to overlap so much that the bosons lose their identity When this happens thatrsquos a Bose-Einstein

Condensate It is only possible at very low temperatures because at high temperatures the individual

bosons have small wave functions and move rapidly which causes them to fly apart

For now applications are still restricted because there are still some setbacks regarding BECs They

are extremely fragile they are being produced in small quantities with just a few million atoms at a time

and finally they can only be made from certain types of atoms Some examples are the atom laser Ketterle

in which a conventional light lase emits a beam of coherent photons this means they are all in phase and

can be concentrated to an extremely small bright spot BECs can slow down light as demonstrated by

Prof Lene Hau PhD in 2001 by the use of a superfluid [7] These manipulations could develop into

new types of telecommunications technology optical storage and quantum computing

BECs are related to super-fluidity and super-conductivity Super-fluidity is the state of matter in

which the behavior is that of a fluid with zero viscosity It was discovered in liquid helium but now it has

applications in astrophysics high-energy physics and theories of quantum gravity

Super-conductivity is a phenomenon of exactly zero electrical resistance and expulsion of magnetic

fields occurring in certain materials when cooled below a characteristic critical temperature A

super-conductor is shown below in figure 2-12

Fig2-12 Super Conductor

25

232 AR Coating Basic Principles

Anti-reflective (AR) coating is a type of optical coating applied to the surface of lenses and other

optical devices (in our case we planned to apply it to a laser diode) to reduce reflection This improves

the efficiency of the system since less light is lost The primary benefit is the elimination of the reflection

itself

When light the medium (glass) it will produce reflection if 100 of the light comes from the air and

enters the glass because therersquos a difference between the index of refraction some of the light will go out

and when the light is coming out of the glass into the air once again because of the difference between

index of refraction some of the light wonrsquot be able to pass through the medium

When the light makes the first trip into the glass there was a loss of about 4 in the reflection and

when the light makes the trip back outside there was another loss of about 4 so when we assume that

100 of the light interacts with the medium actually therersquos just about 92 acting (we neglect the light

absorbed by the glass around 05) To illustrate this idea please refer to figure 2-13

Fig 2-13 Simple Model for Light in Glass Medium

When we apply the AR Coating the light that enters will only have a loss of about 05 and when

making the trip back outside again only 05 of light is loss so we get the result of increasing the light

passing through up to 99 (again neglecting the light absorbed by the glass around 05) To illustrate

this idea please refer to figure 2-14

26

Fig 2-14 Simple Model for Light in Glass Medium after AR Coating

The AR Coating can reduce reflection of incoming light In the case that light hits perpendicular to

the surface of the medium the intensity of the reflection can be calculated using the Reflection

Coefficient

Where n0 and ns are the refractive indices of the first and second media respectively The value of R

varies from 0 (no reflection) to 1 (all light reflected) and is usually quoted as a percentage

Complementary to R is the transmission coefficient or Transmittance If absorption and scattering are

neglected then the value of Transmittance is always 1-R then if a beam of light with intensity I is

incident on the surface a beam of intensity RI is reflected and a beam with intensity TI is transmitted to

the medium

The optimal value is called the Optimal Index of Refraction and is described as

For glass with ns around 15 in air (n0 around 10) then the optimum refractive index will be n1 =

1225

To reduce the refraction in this case we now mean the one that is produced inside the chamber of the

Laser diode the easiest way is to apply a low reflectivity AR coating on the surface of the laser To

measure the appropriate thickness of the coating layer we can use the equations described above By

applying a coat exactly

thickness film we can assure that a certain wavelength is transmitted The

27

reflected waves from the back of the glass medium will be half a wavelength out of phase So they

interfere destructively Because all reflected waves are interfered the maximum amount of light passes

through the coating Please refer to figure 2-15 to illustrate this idea

Fig 2-15 Light Passing through AR Coat and Glass

The most common process to attain this final product is by vacuum deposition For the best coating

results we need to lower the pressure inside the vacuum system to torr

Fig 2-16 Lens without (Top) and With (Bottom) AR Coating

28

233 Laser Diode Basic Principles

A laser diode is a laser whose active medium is a semiconductor similar to that found in

light-emitting diodes (LEDs) Please refer to figure 2-17 The most common type of laser diode is formed

from a p-n junction and powered by injected electric current

Fig 2-17 Laser Diode

Laser diodes are formed by doping a very thin layer on the surface of a crystal wafer The crystal is

doped to produce the n-type region and a p-type region one above the other

By referring to figure 1-2 we can see the basic structure of a working laser When the laser diode has

a current passing through it the light will get excited inside its gain medium and then will start to

resonate this process is called pumping The current exceeds the critical current and then it comes out as

laser light Please refer to figure 1-3 Since we use an external cavity laser we need to apply the AR

coating to the diode and adjust a diffraction grating The laser light comes out the diode and bounces on

the grating making the resonance externally and this becomes the ldquocavityrdquo as shown in figure 2-18

Fig 2-18 Tunable Laser Basic Configuration

29

The most important feature of the external cavity laser is that we can adjust the wavelength easily just

by changing the diffraction gratingrsquos angle and in the end this is the output wavelength of the laser For

different wavelengths there will be different levels of visible light as shown in figure 2-19

Fig 2-19 Light Spectrum

234 Quartz Microbalance System

A Quartz Crystal Microbalance is an instrument that measures a mass per unit area by measuring the

change in frequency of a quartz crystal resonator The resonance is disturbed by the addition or removal

of a small mass due to oxide growthdecay or film deposition (which is the case in our study) at the

surface of the acoustic resonator The QCM can be used under vacuum in gas phase and more recently in

liquid environments It is useful for monitoring the rate of deposition in thin film deposition systems

under vacuum Frequency measurements are easily made with high precision

For our research we used the Sigma Instruments SQM-160 RateThickness Monitor shown in figure

2-20

Fig 2-20 Front and Back Panels of SQM-160

30

The microbalance uses Quartz as the resonator Quartz is one member of the family of crystals that

experience the Piezoelectric Effect

Piezoelectricity is the charge that accumulates in certain solid materials in response to applied

mechanical stress It means electricity resulting from pressure It was discovered in 1880 by Jacques and

Pierre Curie It is understood as the linear electromechanical interaction between the mechanical and the

electrical state in crystalline materials with no inversion symmetry It is a reversible process in that

materials exhibiting direct piezoelectricity also exhibit the reverse This means that the internal generation

of electrical resulting from applied mechanical force and vice versa

By using the piezoelectric effect we can probe as an acoustic resonance by electrical means Applying

alternating current to the quartz crystal induces oscillations This creates a shear wave We can use these

qualities to determine the resonance frequency at high accuracy

The frequency of oscillation of the crystal is partially dependent in the thickness of the crystal During

normal operation all the variables are held constant so a change in thickness correlates directly to a

change in frequency As mass is deposited or etched away the thickness increases or decreases and so the

frequency of oscillation changes accordingly With some simplifying assumptions the frequency change

can be quantified and correlated precisely to the mass change using the Sauerbreyrsquos Equation

Developed by G Sauerbrey in 1959 it is a method for correlating changes in the oscillation

frequency of a piezoelectric crystal with the mass deposited on it It is defined as below

Where f0 is the Resonant frequency Δf is the Frequency change Δm is the mass change A is the

piezoelectrically active area of the crystal q is the Density of quartz (2648 gcmsup3) and μq is the Shear

modulus of quarts(2947x gcmssup2)

Because the film is treated as an extension of thickness Sauerbreyrsquos equation only applies to systems

in which the following 3 conditions are met

Deposited mass must be rigid

Deposited mass must be distributed evenly

The frequency change

lt002

If the change is greater than 2 the Z-match method must be used to determine the change in mass

It is defined as

Where fL is the frequency of the loaded crystal fU is the resonant frequency Nq is the frequency

constant (1668x HzAring) Δm is the mass change A is the piezoelectrically active area of the crystal

31

q is the density of quartz Z is the method constant f is the density of film μq Is the shear modulus of

quarts and μf is the shear modulus of film

The Sauerbrey equation cannot be applied to systems under liquid medium

The crystals are seed crystals plated with gold on both top and bottom for applications A crystal is

shown in figure 2-21 The QCM consists of a thin piezoelectric plate with electrodes evaporated on both

sides Due to the piezoelectric effect AC voltage across the electrodes induces a shear deformation and

vice versa The electromechanical coupling provides a simple way to detect an acoustic resonance by

electrical means

The Z also called Z-factor is a constant value for different materials and it is shown together with the

density of different materials in table 2-2 below

Fig 2-21 QCM Crystals

The Oscillator of the SQM-160 is shown in figure 2-22 and the equivalent circuit for the Resonant

Oscillator is shown in figure 2-23

Fig 2-22 SQM-160 Oscillator

32

Fig 2-23 Oscillator Circuit

33

Table 2-2 Z-Ratios for Different Materials

Table 2-2 Continued

34

Table 2-2 Continued

35

Table 2-2 Continued

36

Table 2-2 Continued

37

Table 2-2 Continued

38

Table 2-2 Continued

235 Vacuum Chamber System

Vacuum Evaporation is the process of depositing thin films of materials onto surfaces The technique

consists of pumping a vacuum chamber to pressures of less than torr and heating a material to

produce a flux of vapor in order to deposit the material onto a surface The material to be vaporized is

typically heated until its vapor pressure is high enough to produce a flux several Angstrom per second by

using an electrically resistive heater or bombardment by a high voltage beam The process was invented

by Henri Nestle in 1886 for food industry

In here the system has been pumped to a vacuum of Torr When a high current is passed

through the filament boat the filament boat is heated over the desired metal evaporation temperature and

so evaporation starts When the evaporation process is finished and the metal cools down crystals

condensate in the surface of the wafer From the weight of the evaporated material the distance between

the filament boat and the wafer we are able to calculate the deposition thickness and we can also use the

mass detector follower like the Quartz crystal resonator microbalance system In the process of

evaporation we usually use a board in between the filament boat and the wafer This is because before we

arrive to the desired evaporation temperature there will be some impurities that will be vaporized in the

controlled environment so we first use a small current and the board in between to get rid of those

impurities and this raises the purity of the deposition material

39

A vacuum evaporation system is shown in figure 2-24

Fig 2-24 Vacuum Evaporation System

Rough Vacuum 760 ~ 1 torr

Medium Vacuum 1 ~ torr

High Vacuum ~ torr

Ultra-High Vacuum Lower than torr

Table 2-3 Classification of Vacuum

For our study we need to use a Turbo Pump A regular turbo pump is shown in figure 2-25

Fig 2-25 Turbo Pump

For our research we used the Pfeiffer TCP 015 Electronic Drive Unit and Granville Phillips 375

Convectron shown below in figure 2-26

40

Fig 2-26 Control and Measurement Equipment

The electronic drive controls the turbo pump and the Convectron measures the pressure inside our

chamber The turbo pump is a type of vacuum pump used to maintain high vacuum Most turbo pumps

are centrifugal When we start the pumping we need to use a mechanical pump so as to decrease the

pressure inside the system from constant atmospheric pressure to torr and then the use dispersion

pump to continue the vacuum until we get to the desired pressure We need to notice though when we

start the dispersion pump we canrsquot turn off the mechanical pump and they both need to run together If

we need to turn off the pumping we first turn off the dispersion pump wait for it to completely stop and

then turn off the mechanical pump

Our completely assembled system is shown in figure 2-27 below

Fig 2-27 Complete System

41

Chapter 3 TENSILE TESTING IN DEPTH

31 Experimentrsquos Purpose and Principles

By means of Universal testing machine and Strain gauges we were able to observe discuss and

analyze the phenomena created when a specimen of certain material is manipulated under an external load

and determine the stress strain and deformation values later we can use the graphing methods of

stress-strain diagram to describe it

The main point of this experiment is that after the tensile specimen is tested use computer analysis

and the actual strain data and after statistical adjustment make the final results report (Tensile testing

experiment is in accordance with ASTM E8)

32 Experimentrsquos Equipment

321 Universal Testing Machine

For the materials testing experiment part of this research we use a Universal Testing Machine as

shown in figure 31 The maximum load it can apply is 100 Ton After the test specimen is secured on the

device with the use of instrumentation the load exerted and the effects of this become apparent on the

specimen and even the smallest of changes can be recorded For our research we used the Chun Yen

Testing Machines Co Ltd 100 Ton Micro Computer Universal Tensile Tester

Fig 31 Universal Testing Machine

42

Table 31 shows the specifications for this machine

Max Capacity 100 Ton

Accuracy plusmn1

Tension (mm) Max Space 1150mm

Grip for Rod 20-70mm

Ram Stroke 250mm

Effective Column Interval 940mm

Crosshead Speed 300mmmin

Testing Speed 0-50mmmin

Volume of Machine 1700times1000times3350mm(LtimesWtimesH)

Volume of Control Panel 1000times800times1500mm(LtimesWtimesH)

Weight 8000kg

Power 3∮220V 20A

Computer AMD K6-2-350

OS Windows XP

Screen 15rdquo CRT

Table 3-1 Chun Yen Testing Machine Specs Table

The connections diagram is shown in figure 3-2

Fig 3-2 Diagram for System Connections

43

When the test specimen is placed when the external force is applied the Load Cell can measure the

size of the applied force and the Encoder measures the expansion rate of change The Local Controller

receives all the information from the 2 units after arranging the results they are displayed in the

computer and they can be afterwards submitted for more complex analysis such as Finite Element

Analysis and we can get the Stress-Strain Diagram

322 Strain Measurement Equipment

The equipment used in our research provides a four-channel measurement that means we can use up

to 4 strain gauges at a time to do our measurements and provides 3 different bridge arrangements as

shown in figure 3-3

(a) (b) (c)

Fig 3-3 Input Connections for Strain Indicator

Figure 3-3 (a) is the Quarter Bridge (b) is the Half Bridge and (c) is the Full Bridge and Transducers

For our study we used the Quarter Bridge and use the Strain Gauge values to decide the position of the

connecting wires The Strain indicator is shown in figure 3-4

Fig 3-4 Vishay Micro-Measurements Model P3 Strain Indicator and Recorder

44

Input Connections Tool Free eccentric lever release

4-channel input

Wire diameter16-28AWG

Bridge Configurations Quarter- Half- and Full Bridge

Bridge Impedance 60-2000Ω

Display 128 64 pixel FSTN positive gray LCD

Data Conversion AD Converter filter

Measurement Range Resolution Strain Range plusmn155mVV

Resolution plusmn00005mVV

Measurement Accuracy plusmn01 of reading plusmn3 counts

Gage Factor Control 0500-9900

Balance Control Software either manual or automatic

Bridge Excitation 15VDC nominal

Communication Interface USB Cable Included

Data Storage Removable Media Card

Shunt Calibration Across bridge completion resistors controlled

by software When Gage Factor=200

120Ω350Ω1000Ω

Analog Output Value 0 to 25V max

Ranges plusmn320 microε plusmn3200 microε plusmn32000 microε

Error 05 output voltage +5mV

Max Error 14 output voltage + 20mV

Update rate 480 samplessec

Output Load 2000Ω

Power Battery Two Alkaline D cells

Battery life 400 hours typ

USB 5V 100mA

Operational Environment Temperature 0-50

Humidity Up to 90 Non-condensing

Case Aluminum Alloy

Size and Weight 228times152times152(mm) 20(kg)

Table 3-2 Vishay Micro-Measurements Model P3 Strain Indicator and Recorder Specs

45

323 Strain Gauge

The strain gaugersquos main basic principle is to use a resistancersquos characteristics to measure the strain

The inside connections of the strain indicator are shown in figure 3-5

Fig 3-5 Inner Connections

As shown above this is a quarter-bridge connection We connect equal-length 3 wires to the 2

connections allowed by the strain gauge wire 1 and 3 can be used to cancel out the effects of temperature

to the resistance and because of the addition of wires 1 and 3 wire 2 can directly measure the experiment

results from the strain gauge and therefore the strain developed with no influence of temperature

If there were no two measuring leads then the relations will be

R 4 =R g +2R L

Where Rg is the Strain Gauge Value and RL is the wire resistance then

4

4

R

R=

Lg

g

RR

R

2

=

gL

gg

RR

RR

21

amp

4

4

R

R=

g

g

R

R(1- L)

Where L is the Signal Loss Factor and so

L =gL

gL

RR

RR

21

2

g

L

R

2R if

g

L

R

2Rltlt1

46

(Actual Value R g =120R L =08g

L

R

2Ris always much smaller than 1)

R 4 =R g +2R LR 2 =R 3 =rR gR 1 =R g 32 RR =0

V 0 =V 2)1( r

r

(

4

4

R

R-

1

1

R

R)

The first term describes loss attenuation effects second term describes loss of balancing capabilities

effects

V 0 =V 2)1( r

r

[

)2

(Lg

g

RR

R

+

T

Lg

g

RR

R

)

2( + T

Lg

L

RR

R

)

2

2( -(

g

g

R

R) T ]

The first term describes loss attenuation effects and loss of balancing capabilities effects the second

third and fourth terms describe the temperature effects on the wire

For the three-wire method we have

L =gL

gL

RR

RR

1

g

L

R

R if

g

L

R

Rltlt1

V 0 =V 2)1( r

r

[

)(Lg

g

RR

R

+

T

Lg

g

RR

R

)( + T

Lg

L

RR

R

)

2( -

T

Lg

g

RR

R

)( - T

Lg

L

RR

R

)

2( ]

V 0 = V2)1( r

r

)(

Lg

g

RR

R

In the last four terms inside parenthesis we can see the effects of temperature being cancelled out and the

effect on first term is not great so this is the reason why in our research we use three wires

47

324 Specimen Measurements

The tensile specimens used in this research are compliant of ASTM E8 Tensile parameters as shown

in figure 3-6

Fig 3-6 Tensile Specimen

Diameter

D(mm)

Gauge

Length

G(mm)

Smallest

Arc

Radius

R(mm)

Shortest

Area

A(mm)

Total

Length

L(mm)

Clamping

Area

Length

B(mm)

Clamping

Area

Diameter

C(mm)

Bar 125 02 625 01 gt10 gt75 ~ 145 ~ 35 20

Table 3-3 Specifications for Round Bar

33 Experiment Procedure

1 Attaching the Strain Gauge to the Tensile Specimen

(1) Prepare 1 ASTM E8 compliant tensile specimen round bar as shown in figure 3-7

(2) Prepare Strain Gauge as those described in table 3-4

(3) Prepare other consumables and adhesive agent such as epoxy adhesive or

cyanoacrylate adhesive as shown in figure 3-8

48

Fig 3-7 Actual Tensile Specimen

Fig 3-8 Other Materials Used (Such as Alcohol gauze transparent tape adhesive)

Gage Type

EA-06-120LZ-120E

Resistance in ohms at 24∘C

1200plusmn03

Gage Factor at 24∘C

2075plusmn05

Transverse Sensitivity at 24∘C

(+07plusmn02)

Table 3-4 Specifications for Strain Gauge

2 Attaching Strain Gauge

As shown in following figures we shall explain the attachment of the strain gauge

(1) Use sand paper and a rasp to clean thoroughly the surface where the strain gauge will be

attached to

49

(a)

(2) Use alcohol to wash the surface where the strain gauge will be attached and use gauze to rub

it off

(b)

(3) Find a clean surface and clean it with alcohol and gauze

(c)

(4) Place the strain gauge in the clean surface Use a piece of transparent tape on top of the strain

gauge after securely placed rip it off the surface carefully

50

(d)

(5) Use a piece of white paper to mark the place where the strain gauge will be attached and in

this way we can make sure that the strain gauge will be placed as horizontally and vertically

correct as possible

(e)

(6) In the place where we had our mark place the strain gauge

(f)

(7) Carefully lift one side of the tape and apply some of the adhesive agent to both the strain

gauge and specimenrsquos surface

(g)

51

(8) We need to make sure that the gauge and the specimen will be firmly attached so we gently

apply pressure with our thumb

(h)

(9) After the adhesive is fully dry we can carefully rip off the tape

(i)

(10) We need to do the whole process twice one for the horizontally placed strain gauge and one

for the vertically placed strain gauge

52

(j)

(11) We now proceed to solder the wires to the strain gauge

(k)

(12) After soldering we use a Volt Multimeter to measure that there is no contact between wires

If there is none then the specimen is ready for testing

(l)

(13) We now need to measure a 5cm distance and mark it to check and compare the elongation

before and after the tensile testing

(m)

53

Fig 3-9 Specimen-Strain Gauge Process

3 Tensile Test

(1) Enter the computer application that controls the tensile testing machine

(2) Turn on the tensile testing machine main switch

(3) Adjust the hydraulic pump to go back to its original position

(4) Bring the lowering motor down to a distance enough so as to attach the tensile specimen to the

system open the clamps and secure the specimen

(a)

(5) Connect all the necessary wires to the strain indicator equipment

54

(b)

(6) Start the ascending motor and wait for the expansion

(c)

Fig 3-10 Specimen-Tensile Testing Process

4 Start the Test

(1) Enter the software application and enter some variables needed for the experiment in the

specific screen

(2) Go back to the main screen and press the [測試] (measure) button to start the test and auto

recording in the software

(3) After the specimen breaks the mechanical device will automatically stop and ask the user to

enter the total displacement We take out the specimen from the testing machine and adjust the

machinersquos position back to its original position

(4) Save the results information

(5) Record the results from the strain indicator

34 Results

From this experiment we can get the Poissonrsquos Ratio Youngrsquos Modulus and Yield Strength etc and

because of the slippage phenomenon in the clamp at the moment of the test then the Elastic Limit will

display some yield phenomena So omit any undesirable results we just take the Yield portion of the

results as reference

In the process of the experiment the most important part to attend to is the attaching of the strain

gauge because the gaugersquos purpose is to measure the strain developed during the test and this strain

might be very small If the gaugersquos angle change during the test ie is not well attached this will affect

the accuracy of the measurements of Poissonrsquos ratio and Youngrsquos modulus

55

The materials provided by the manufacturer are SUM 23 and SUM 43 steel round bars and these two

types of materials have been through different heat treatment processes so they can be sub-divided

further into untreated material heat-treated material and black surface heat treated material for the two

materials with heat treatment the treatment process and finished are different In the end we only have

the mechanical properties that were calculated after our research of these materials

All of the specifications are identical to those shown in figure 3-6

341 SUM 23

Fig 3-11 SUM 23 Untreated Material

Number 7 10

Hardness(HRB) 74 75

Yield Stress (MPa) 448 440

Tensile Strength (MPa) 544 560

Poissonrsquos Ratio 029 027

Youngrsquos Modulus (GPa) 203 210

Cut-off Area Shrinking () 42 41

Elongation () 1125 1011

Table 3-5 Mechanical Properties of SUM 23 Untreated

56

Stress-Strain Diagram

(a)

(b)

57

Fig 3-12 Stress-Strain Diagrams for (a) 7 Round Bar and (b) 10 Round Bar

Cut-Off Area

(a)

(b)

Fig 3-13 Cut-Off Area of (a) 7 Round Bar and (b) 10 Round Bar

58

SUM 23 Nickel Round Bar

Fig 3-14 SUM 23 Nickel Material

Number 1 2 3 4

Hardness(HRB) 48 50 49 48

Yield Stress (MPa) 370 370 380 400

Tensile Strength (MPa) 455 451 450 450

Poissonrsquos Ratio 028 046 029 026

Youngrsquos Modulus (GPa) 243 303 246 206

Cut-off Area Shrinking () 803 803 726 601

Elongation () 566 65 602 647

Table 3-6 Mechanical Properties of SUM 23 Nickel

59

Stress-Strain Diagram

(a)

60

(b)

(c)

(d)

61

Fig 3-15 Stress-Strain Diagrams for (a) 1 Round Bar (b) 2 Round Bar (c) 3 Round Bar and (d)

4 Round Bar

Cut-Off Area

(a)

(b)

62

(c)

(d)

Fig 3-16 Cut-Off Area of (a) 1 Round Bar (b) 2 Round Bar (c) 3 Round Bar and (d) 4 Round

Bar

63

SUM 23 Black Surface Round Bar

Fig 3-17 SUM 23 Black Surface Material

Number 1 2 3

Hardness(HRB) 51 50 51

Yield Stress (MPa) 378 371 369

Tensile Strength (MPa) 467 465 464

Poissonrsquos Ratio 03 016 04

Youngrsquos Modulus (GPa) 215 266 266

Cut-off Area Shrinking () 986 94 848

Elongation () 748 805 761

Table 3-7 Mechanical Properties of SUM 23 Black Surface Material

64

Stress-Strain Diagram

(a)

(b)

65

(c)

Fig 3-18 Stress-Strain Diagrams for (a) 1 Round Bar 2 Round Bar and (c) 3 Round Bar

Cut-Off Surface

(a)

66

(b)

(c)

Fig 3-19 Cut-Off Surface of (a) 1 Round Bar 2 Round Bar and (c) 3 Round Bar

67

342 SUM 43

Fig 3-20 Untreated SUM 43 Untreated Material

Number 1 5

Hardness(HRB) 76 75

Yield Stress (MPa) 572 594

Tensile Strength (MPa) 743 785

Poissonrsquos Ratio 027 029

Youngrsquos Modulus (GPa) 200 202

Cut-off Area Shrinking () 338 2944

Elongation () 857 894

Table 3-8 Mechanical Properties of SUM 43 Untreated

68

Stress-Strain Diagrams

(a)

(b)

Fig 3-21 Stress-Strain Diagrams for SUM 43 (a) 1 Round Bar and (b) 5 Round Bar

69

Cut-Off Area

(a)

(b)

Fig 3-22 Cut-Off Area of SUM 43 (a) 1 Round Bar and (b) 5 Round Bar

70

SUM 43 Nickel Round Bar

Fig 3-23 SUM 43 Nickel Material

Number 4 5

Hardness(HRB) 51 50

Yield Stress (MPa) 1580 1544

Tensile Strength (MPa) 1639 1625

Poissonrsquos Ratio 03 028

Youngrsquos Modulus (GPa) 194 201

Cut-off Area Shrinking () 1697 137

Elongation () 376 265

Table 3-9 Mechanical Properties of SUM 43 Nickel

71

Stress-Strain Diagrams

(a)

(b)

Fig 3-24 Stress-Strain Diagrams for (a) 4 Round Bar and (b) 5 Round Bar

72

Cut-Off Area

(a)

(b)

Fig 3-25 Cut-Off Area of (a) 4 Round Bar and (b) 5 Round Bar

73

SUM 43 Black Surface Material

Fig 3-26 SUM 43 Black Surface Material

Number 3 5

Hardness(HRB) 56 56

Yield Stress (MPa) 1416 1361

Tensile Strength (MPa) 1591 1402

Poissonrsquos Ratio 029 031

Youngrsquos Modulus (GPa) 200 202

Cut-off Area Shrinking () 139 124

Elongation () 24 24

Table 3-10 Mechanical Properties of SUM 43 Black Surface Material

74

Stress-Strain Diagrams

0 2 4 6 8 10 12 14

-200

0

200

400

600

800

1000

1200

1400

1600

1800

應力 (MPa)

應變()

(a)

0 2 4 6 8 10

-200

0

200

400

600

800

1000

1200

1400

1600

應力

(MPa)

位移 ()

(b)

Fig 3-27 Stress-Strain Diagrams for (a) 3 Round Bar and (b) 5 Round Bar

(Note These curves were formulated using Visual Solutions Inc VisSim Software)

75

Cut-Off Area

(a)

(b)

Fig 3-28 Cut-Off Area of (a) 3 Round Bar and (b) 5 Round Bar

76

The force value (N) was retrieved from the Universal Testing Machine

The Poissonrsquos Ratio (ε) is calculated as

ε =

the values for the Poissonrsquos Ratio are in average around 0297

The Youngrsquos Modulus (E) is calculated as

E =

Where

Stress =

Cross-sectional Area =

where D is the Diameter

The value for D was in average around 1258 mm

The values shown by the computer because there is Slippage phenomena between the Clamp and the

specimen will not be taken into consideration for the elongation strain and Youngrsquos modulus and we will

refer to the values that we have meticulously calculated

77

Chapter 4 AR COATING IN DEPTH

41 Experimentrsquos Purpose and Principles

By means of a vacuum chamber and several other instruments we intend to apply Anti-Reflective

Coating using deposition process to a laser diode and in this way reduce its refraction so as to make it

lose less light in the process of amplification and we can control certain wavelengths we want produced

for certain desired applications in our case we are attempting to re-create a Bose-Einstein Condensate

An optimal BEC apparatus is shown in figure 4-1

Fig 4-1 BEC Apparatus

The main point of this experiment is to build a vacuum chamber system attach all the instrumentation

needed (Vacuum pump deposition meter and voltmeter) and use it to apply AR coating to a laser diode

After we have accomplished the AR coating other team will be in charge of designing the BEC apparatus

and use the results of our research

78

42 Experimentrsquos Equipment

421 Vacuum Chamber

For this research we designed a vacuum chamber whose main body is shown in figure 4-2 Its

dimensions are

Width 240 mm

Length 240 mm

Height 200 mm

Outer Diameter 4 in

Inner Diameter 15 in

Fig 4-2 Vacuum Chamber Main Body

The chamber is made up of 6 pass ways pass way A is the connection with the Laser Deposition

Equipment pass way B is the connection with the Turbo Pump and pass way C is for the connection with

the Deposition Source

A

C

B

79

Pass way C is for the deposition source as mentioned above This is a system where a thermal

resistance is heated by passing a high current through it which heats up a filament boat (made of tungsten)

where the material to be evaporated is place We control the temperature as such that the material will

evaporate and the heat will not cause the filament boat to crack

Because P = Isup2 R (where P is power I is current and R is resistance) to avoid the current to flow

where it is not desired we decided that the material for the Thermocouple shown in figure 4-3 should be

Copper ᴓ 63 mm We choose it that way because Copper has very good heat dissipation characteristics

and the resistance value is low It can reduce the value of the current enough to make the thermocouple to

create heat

Fig 4-3 Thermocouple

To the thermocouple we attach the tungsten filament boat We need to take notice of materials to be

used in this design because when using high current the tungsten filament boar will heat up and so the

material must be able to keep up with the heating potential of tungsten and has a low coefficient of heat

dissipation to avoid the tungsten to fail when heating up and therefore not evaporating Considering all

this we decide to use Stainless Steel

Because this clamp will be assembled inside the chamber after many revisions it was determined it

will have the shape shown in figure 4-4

Fig 4-4 Filament Boat Clamp Design

80

For the tungsten filament boat we bought the product from a distributor The dimensions are

Length 100 mm

Width 10 mm

Height 1 mm

Our thermocouple is 15 in but the pass way C is 4 in so we need to attach a Flange that connects

15in to 4in Because these specifications are quite difficult to achieve by Milling we had to use

electrical wire cutting

For the laser clamping system where the laser that is going to be AR coated will be placed will be

connected to pass way A the assembly is shown in figure 4-5 below

Fig 4-5 Cover Assembly

For this design we used an O-ring instead of a gasket so as to save time The design of the assembly

where the laser will be placed is shown in figure 4-6

Fig 4-6 Upper Cover Inner Assembly

D

E

F

81

Point D is the plate in the assembly where the laser diode will be fixed Because of the easy

processing we decide to use Aluminum and it is screwed to the top cover Point E is the connection for

the Quartz crystal resonator and it is designed in the same as point F in this way the results of the quartz

microbalance system will be more accurate in real time Point F is the final resting place for the laser

diode We use a Thor Labs Base with dimensions of ᴓ 9mm and ᴓ 56mm for two different size laser

diodes It just needs to be plugged in for easy installation

From figure 4-6 we know that the system needs signal system connections and because of the

change in temperature inside the chamber this could affect the functioning of the quartz microbalance so

we also need to install water tubes for cooling This is shown in figure 4-7 below

Fig 4-7 Diagram of Upper Cover Connections

In figure 4-8 we show the Feed through connections and their functions

Fig 4-8 Feed through Diagram

82

1 SQM-160 wire 5 Laser Connection 1 (Vin)

2 SQM-160 (G) 6 Laser Connection 2 (G)

3 K-Type-1 7 Laser Connection 3 (PD)

4 K-Type-2 8 Not In Use

The fully assembled chamber is shown in figure 4-9

Fig 4-9 Fully Assembled Chamber

422 Quartz Crystal Microbalance

For measuring the deposition on our target for coating we used the Inficon SQM-160 RateThickness

Monitor It is an easy to use instrument for measuring many types of thin-film coatings as shown in

figure 4-10

(a) Front Panel (b) Back Panel

Fig 4-10 Inficon SQM-160

83

Table 4-1 shows the technical specifications for this equipment

Number of sensors 2 Standard 4 additional optional

Sensor Frequency Range 40 MHz ~ 60 MHz

Reference Frequency Accuracy 002

Thickness Display Resolution 1 Aring

Thickness Resolution 015 Aring (Std) 0037 Aring (Hi Res)

Density of Stored Films 05-9999 gmcc

Tooling 10-399

Z-Factor 010-1000

Final Thickness 0000-9999k Aring

Measurement Period 15 to 2 sec

Simulation Mode Yes

Frequency Mode Yes

Rate Resolution 011 Arings

Dual Crystal Yes

Etch Mode Yes

Crystal Tooling 10-399

Crystal Fail Min Max 40 to 60 MHz 41 to 61 MHz

Power 100-120 200-240~plusmn10 nominal 20W

Operation Environment 0degC ~ 50degC

0 ~ 80 RH non-condensing

0 ~ 2000 meters

Class 1 Equipment

Pollution Degree 2

Rack Dimensions 885mm x 2127mm x 1969mm

Weight 27 kg

Table 4-1 Inficon SQM-160 RateThickness Monitor Specs

84

To the SQM-160 we need to connect an Oscillator We use the Sigma Instruments Remote Oscillator

Ser No 2 268 as shown in figure 4-11

Fig 4-11 Sigma Instruments Remote Oscillator

The connections diagram is shown in figure 4-12

Fig 4-12 SQM-160 Connections Diagram

85

423 Turbo Pump

For our experiments we used the Pfeiffer TCP 015 Electronic Drive Unit shown below in figure 4-13

Table 4-2 shows the technical specifications for this equipment

(a) Front Panel (b) Back Panel

Fig 4-13 Pfeiffer TCP 015 Electronic Drive

Connection Voltage (100V) 90-112

Mains Frequency 5060 Hz

Start-up Current 22 A

Nominal Frequency 1500 Hz

Rotation Speed 10V = 1500Hz plusmn2

Analog Output Current 10 V = 25 A plusmn 5

Rotation Speed Switchpoint 750 Hz

Works Setting 8 min

Permissible Ambient Temperature 0degC ~ 40degC

Dimensions Front Panel 1285mm x 1063mm

Insertion Length 227mm

Weight 27 Kg

Table 4-2 Pfeiffer TCP 015 Electronic Drive Specs

86

The connections diagram is shown in figure 4-14

Fig 4-14Connections Diagram for Pfeiffer TCP 015

To measure the pressure inside the chamber we use the Granville Phillips 375 Convectron Vacuum

Pressure Controller shown in figure 4-15

(a) Front Panel (b) Back Panel

Fig 4-15 Granville Phillips 375 Convectron

87

Its dimensions are shown in figure 4-16

Fig 4-16 Dimensions of Convectron

Table 4-3 shows the technical specifications for this equipment

Table 4-3 Granville Phillips 375 Convectron Vacuum Pressure Controller Specs

88

424 Multimeter

For our experiment we used the Keithley 2000 Digital Multimeter as shown in figure 4-17

(a) Front Panel (b) Back Panel

Fig 4-17 Keithley Model 2000 6-12-Digit Digital Multimeter

Its technical specifications are shown in table 4-4

Table 4-4 Keithley Model 2000 6-12-Digit Digital Multimeter Specs

89

43 Experiment Procedure

1 Connecting together the equipment and the chamber

(1) We first connect the resonator to the thickness monitor and connect the other side to the

chamber

(2) We now connect the flexible tubes to the turbo pump on one side and to the chamber on the

other

(3) We need to check that tubes are tightly connected to avoid any leaks in the vacuum pumping

process which will not allow us to get to our goal of Torr As shown in figure 4-18

(4) Connect the convectron to the system as shown in figure 4-19

Fig 4-18 checking for leaks using alcohol

Fig 4-19 Convectron attached to System

90

(5) Attach the clamps of the Multimeter to the bottom of the chamber as shown in figure 4-20

(6) Place the Quartz crystal in place

(7) Close tight vacuum chamber

(8) Connect all electrical appliances to power source

Fig 4-20 Multimeter Connections

2 Starting up the System

(1) We turn on all the devices as such Check all systems are ready to function Reset all values

that might be left over from previous tests

(2) Start the thickness monitor and set all values for this experiment In our case we got to testing

the system but not actual coating So we used the simulation mode of the thickness monitor as

shown in figure 4-21

Fig 4-21 Simulation Mode

91

(3) Start the turbo pump Make sure the lid on the vacuum chamber is tightly closed

(4) Start convectron and record initial pressure

(5) Start Multimeter and record initial current

3 Coating Process

(1) If we have the deposition material inside the filament boat the power source for the high

current must be started as well

(2) Record all initial values for thickness current pressure

(3) For an ideal experiment we need a thickness of around 101 nm a pressure of Torr and

a current of 300 A

44 Results

From previous experiments we have shown that we can turn a LED into a laser by means of AR

Coating In figure 4-22 shown below we can compare the actual results of a Diode before and after AR

coating From the blue line we can see that when the diode is at a current of 15mA its light will change

from LED to laser and if we look at the red line its critical current is around 30 to 35 mA

Fig 4-22 AR Coating Comparison for Laser Diodes

This means that the light emitted is not as strong as if the diode had been coated because inside the

chamber there must be some excitation first so the reflectivity of both sides inside the diode must be high

So because of the coating in one of the sides we have opened a door and let the light come out so the

critical current is risen as such and will be higher value than that of before the coating

92

In the following figures we can see the difference between before and after coating in a material The

thickness is around 1016 nm for this material

Fig 4-23 Before Coating

Fig 4-24 After Coating

93

Chapter 5 CONCLUSIONS AND RECOMMENDATIONS

51 Conclusions

For the first part of this independent study taking into consideration the data that came out of our

research and that sent by the provider we can say

1 SUM 23 after heat treatment will unexpectedly develop cracking in the middle of the tensile

testing process and suddenly break

2 Itrsquos possible that in the process of heat treatment to the SUM 23 material the treatment was not

uniform and this will create a pre-loaded moment force on one side that pushes on the other side

of the specimen resulting in material deformation

3 In the process of attaching the strain gauges to the materials it is very easy to make errors due to

poor adhesion or sudden removal in the tensile testing process

For our second part of the independent study the following can be made

1 At the beginning of this independent study we had no idea what Bose-Einstein Condensate was

or what was its purpose After much literature we finally comprehended the basic principles to

put into practice for our research

2 Our systemrsquos basic working principles and equipmentrsquos complexity are a little difficult to grasp

but hopefully we were able to understand enough of it

3 Theoretically from relation between the power and current we can know the advantages and

disadvantages of AR Coating

4 We were able to assemble the system and run test on its functions Even though we were able to

do this there is still much more work left to do with this system

52 Recommendations

For the Tensile Testing the following can be said

1 Ask the provider to check on the process of heat treatment on the SUM 23 material and give

them the information we have gathered through our test so they can correct for the mechanical

properties found if any change is needed

2 To avoid the problem of the inaccuracy of the poor adhesion of strain gauges we can attach

multiple strain gauges to the same one specimen so as to correlate data and improve our results

For the AR Coating the following can be said

1 We need to make sure that there are no physical defects on the main body of the chamber so as to

achieve maximum efficiency in the vacuum process If there was then the vacuum will arrive to

certain point and then start to decrease

2 It would be preferable to add some sort of visual aid that will allow the user to check the inside of

the chamber without actually opening it This will help us determine at what times we should

manipulate the current to better evaporate the substrate

94

REFERENCES

[1] A L Window Strain Gauge Technology Elsevier Applied Science London and New York 2nd

Edition 1992

[2] CC Perry and HR Lissner Strain Gauge Primer McGraw-Hill Book Co Inc New York 1955

[3] James W Dally William F Riley McGraw-Hill 1978

[4] University of Colorado Boulder BEC - What is it and where did the idea come from

httpwwwcoloradoeduphysics2000becwhat_is_ithtml

[5] Ultraslow Light amp Bose-Einstein Condensates Two-way Control with Coherent Light amp Atom

Fields Harvard Hau Lab Dr Lene Vestergaard Hau Optics amp Photonics News 16 1995

[6] The Art of Taming Light Ultra-slow and Stopped Light Harvard Hau Lab Dr Lene

Vestergaard Hau Europhysics News 2004

[7] Nonlinear Optics Shocking Superfluids Harvard Hau Lab Dr Lene Vestergaard Hau Nature

Physics 2007

[8] Model P3 Strain Indicator and Recorder Instruction Manual Vishay Micro-Measurements 2005

[9] Granville-Phillips Series 375 Convectron Vacuum Gauge Controller Instruction Manual Brooks

Automation 2008

[10] Effect of Film Thickness on the Validity of the Sauerbrey Equation for Hydrated Polyelectrolyte

Films Vogt Lin Wu White 2004

[11] Quartz Crystal Microbalance Study of DNA Immobilization and Hybridization for DNA Sensor

Development Chang Zhao 2008

[12] Installation of Strain Gages with SR-4 PrecoatAdhesive Vishay Micro-Measurements 2005

[13] Strain Gauge Measurement ndash A Tutorial National Instruments 1998

[14] Correlation between Vickers Hardness Number and Yield Stress of Cold-Formed Products

Yavuz Tekkaya

[15] httpsenwikipediaorg

Page 23: PC Hinge Materials Testing and AR Laser Diode Coating

23

Tc =

(

)

asymp 33125

Where Tc is the critical temperature n is the particle density m is the mass per boson h is the

reduced Planck constant k is the Boltzmann constant and ζ is the Riemann zeta function

There are two classes of elementary particles defined by whether their quantum spin is a nonnegative

integer or an odd half integer A Bose-Einstein Condensate is shown below in figure 2-11

Fig 2-11 Bose Einstein Condensate at different scales

Bosons are the particles whose quantum spin is a nonnegative integer (s = 0 1 2 etc) Examples of

bosons include fundamental particles (Higgs Boson Photons W and Z Bosons Gluons Gravitons etc)

composite particles (Mesons Hadrons Nuclei and Atoms of Carbon-12 and Helium-4) and

quasi-particles Bosons are considered force carrier particles The Bosons differ from Fermions in that

there is no limit to the number that can occupy the same quantum state This is called the Pauli Exclusion

Principle

The Pauli Exclusion Principle says that no two identical fermions may occupy the same quantum state

simultaneously in other words this means that the total wave function for two identical fermions is

anti-symmetric with respect to exchange of the particles This means that no two electrons in a single

atom can have the same four quantum numbers

Fermion is any particle characterized by Fermi-Dirac Statistics and follows the Pauli Exclusion

Principle described above Quarks Leptons and composite particles (Hadrons Nuclei and Atoms of

Carbon-13 and Helium-3) made of an odd number of these are considered Fermions It can be an

elementary particle such as the electron or a composite particle such as the protons Following the Pauli

24

Exclusion Principle only one fermion can occupy a particular quantum state at any given time If multiple

fermions have the same spatial probability distribution then at least one property of each fermion must be

different Fermions are usually associated with matter because composite fermions are key building

blocks of matter (neutrons and protons)

Fermionsrsquo behavior by the Fermi-Dirac Statistics which describes the energies of single particles in a

system comprising of many identical particles It applies to identical particles with half-odd integer spin

in a system of thermal equilibrium The particles in the system are assumed to have negligible mutual

interaction This allows the many-particle system to be described in terms of single-particle energy states

The result is the Fermi-Dirac distribution of particles over these states and includes the condition that no

two particles can occupy the same state which has considerable effect on the properties of the system

In quantum mechanics the position of an object is uncertain An object has a definite probability of

being at any given point in space This probability is encoded in the wave function mentioned earlier If

one concentrates a large number of identical bosons in a small region then it is possible for their wave

functions to overlap so much that the bosons lose their identity When this happens thatrsquos a Bose-Einstein

Condensate It is only possible at very low temperatures because at high temperatures the individual

bosons have small wave functions and move rapidly which causes them to fly apart

For now applications are still restricted because there are still some setbacks regarding BECs They

are extremely fragile they are being produced in small quantities with just a few million atoms at a time

and finally they can only be made from certain types of atoms Some examples are the atom laser Ketterle

in which a conventional light lase emits a beam of coherent photons this means they are all in phase and

can be concentrated to an extremely small bright spot BECs can slow down light as demonstrated by

Prof Lene Hau PhD in 2001 by the use of a superfluid [7] These manipulations could develop into

new types of telecommunications technology optical storage and quantum computing

BECs are related to super-fluidity and super-conductivity Super-fluidity is the state of matter in

which the behavior is that of a fluid with zero viscosity It was discovered in liquid helium but now it has

applications in astrophysics high-energy physics and theories of quantum gravity

Super-conductivity is a phenomenon of exactly zero electrical resistance and expulsion of magnetic

fields occurring in certain materials when cooled below a characteristic critical temperature A

super-conductor is shown below in figure 2-12

Fig2-12 Super Conductor

25

232 AR Coating Basic Principles

Anti-reflective (AR) coating is a type of optical coating applied to the surface of lenses and other

optical devices (in our case we planned to apply it to a laser diode) to reduce reflection This improves

the efficiency of the system since less light is lost The primary benefit is the elimination of the reflection

itself

When light the medium (glass) it will produce reflection if 100 of the light comes from the air and

enters the glass because therersquos a difference between the index of refraction some of the light will go out

and when the light is coming out of the glass into the air once again because of the difference between

index of refraction some of the light wonrsquot be able to pass through the medium

When the light makes the first trip into the glass there was a loss of about 4 in the reflection and

when the light makes the trip back outside there was another loss of about 4 so when we assume that

100 of the light interacts with the medium actually therersquos just about 92 acting (we neglect the light

absorbed by the glass around 05) To illustrate this idea please refer to figure 2-13

Fig 2-13 Simple Model for Light in Glass Medium

When we apply the AR Coating the light that enters will only have a loss of about 05 and when

making the trip back outside again only 05 of light is loss so we get the result of increasing the light

passing through up to 99 (again neglecting the light absorbed by the glass around 05) To illustrate

this idea please refer to figure 2-14

26

Fig 2-14 Simple Model for Light in Glass Medium after AR Coating

The AR Coating can reduce reflection of incoming light In the case that light hits perpendicular to

the surface of the medium the intensity of the reflection can be calculated using the Reflection

Coefficient

Where n0 and ns are the refractive indices of the first and second media respectively The value of R

varies from 0 (no reflection) to 1 (all light reflected) and is usually quoted as a percentage

Complementary to R is the transmission coefficient or Transmittance If absorption and scattering are

neglected then the value of Transmittance is always 1-R then if a beam of light with intensity I is

incident on the surface a beam of intensity RI is reflected and a beam with intensity TI is transmitted to

the medium

The optimal value is called the Optimal Index of Refraction and is described as

For glass with ns around 15 in air (n0 around 10) then the optimum refractive index will be n1 =

1225

To reduce the refraction in this case we now mean the one that is produced inside the chamber of the

Laser diode the easiest way is to apply a low reflectivity AR coating on the surface of the laser To

measure the appropriate thickness of the coating layer we can use the equations described above By

applying a coat exactly

thickness film we can assure that a certain wavelength is transmitted The

27

reflected waves from the back of the glass medium will be half a wavelength out of phase So they

interfere destructively Because all reflected waves are interfered the maximum amount of light passes

through the coating Please refer to figure 2-15 to illustrate this idea

Fig 2-15 Light Passing through AR Coat and Glass

The most common process to attain this final product is by vacuum deposition For the best coating

results we need to lower the pressure inside the vacuum system to torr

Fig 2-16 Lens without (Top) and With (Bottom) AR Coating

28

233 Laser Diode Basic Principles

A laser diode is a laser whose active medium is a semiconductor similar to that found in

light-emitting diodes (LEDs) Please refer to figure 2-17 The most common type of laser diode is formed

from a p-n junction and powered by injected electric current

Fig 2-17 Laser Diode

Laser diodes are formed by doping a very thin layer on the surface of a crystal wafer The crystal is

doped to produce the n-type region and a p-type region one above the other

By referring to figure 1-2 we can see the basic structure of a working laser When the laser diode has

a current passing through it the light will get excited inside its gain medium and then will start to

resonate this process is called pumping The current exceeds the critical current and then it comes out as

laser light Please refer to figure 1-3 Since we use an external cavity laser we need to apply the AR

coating to the diode and adjust a diffraction grating The laser light comes out the diode and bounces on

the grating making the resonance externally and this becomes the ldquocavityrdquo as shown in figure 2-18

Fig 2-18 Tunable Laser Basic Configuration

29

The most important feature of the external cavity laser is that we can adjust the wavelength easily just

by changing the diffraction gratingrsquos angle and in the end this is the output wavelength of the laser For

different wavelengths there will be different levels of visible light as shown in figure 2-19

Fig 2-19 Light Spectrum

234 Quartz Microbalance System

A Quartz Crystal Microbalance is an instrument that measures a mass per unit area by measuring the

change in frequency of a quartz crystal resonator The resonance is disturbed by the addition or removal

of a small mass due to oxide growthdecay or film deposition (which is the case in our study) at the

surface of the acoustic resonator The QCM can be used under vacuum in gas phase and more recently in

liquid environments It is useful for monitoring the rate of deposition in thin film deposition systems

under vacuum Frequency measurements are easily made with high precision

For our research we used the Sigma Instruments SQM-160 RateThickness Monitor shown in figure

2-20

Fig 2-20 Front and Back Panels of SQM-160

30

The microbalance uses Quartz as the resonator Quartz is one member of the family of crystals that

experience the Piezoelectric Effect

Piezoelectricity is the charge that accumulates in certain solid materials in response to applied

mechanical stress It means electricity resulting from pressure It was discovered in 1880 by Jacques and

Pierre Curie It is understood as the linear electromechanical interaction between the mechanical and the

electrical state in crystalline materials with no inversion symmetry It is a reversible process in that

materials exhibiting direct piezoelectricity also exhibit the reverse This means that the internal generation

of electrical resulting from applied mechanical force and vice versa

By using the piezoelectric effect we can probe as an acoustic resonance by electrical means Applying

alternating current to the quartz crystal induces oscillations This creates a shear wave We can use these

qualities to determine the resonance frequency at high accuracy

The frequency of oscillation of the crystal is partially dependent in the thickness of the crystal During

normal operation all the variables are held constant so a change in thickness correlates directly to a

change in frequency As mass is deposited or etched away the thickness increases or decreases and so the

frequency of oscillation changes accordingly With some simplifying assumptions the frequency change

can be quantified and correlated precisely to the mass change using the Sauerbreyrsquos Equation

Developed by G Sauerbrey in 1959 it is a method for correlating changes in the oscillation

frequency of a piezoelectric crystal with the mass deposited on it It is defined as below

Where f0 is the Resonant frequency Δf is the Frequency change Δm is the mass change A is the

piezoelectrically active area of the crystal q is the Density of quartz (2648 gcmsup3) and μq is the Shear

modulus of quarts(2947x gcmssup2)

Because the film is treated as an extension of thickness Sauerbreyrsquos equation only applies to systems

in which the following 3 conditions are met

Deposited mass must be rigid

Deposited mass must be distributed evenly

The frequency change

lt002

If the change is greater than 2 the Z-match method must be used to determine the change in mass

It is defined as

Where fL is the frequency of the loaded crystal fU is the resonant frequency Nq is the frequency

constant (1668x HzAring) Δm is the mass change A is the piezoelectrically active area of the crystal

31

q is the density of quartz Z is the method constant f is the density of film μq Is the shear modulus of

quarts and μf is the shear modulus of film

The Sauerbrey equation cannot be applied to systems under liquid medium

The crystals are seed crystals plated with gold on both top and bottom for applications A crystal is

shown in figure 2-21 The QCM consists of a thin piezoelectric plate with electrodes evaporated on both

sides Due to the piezoelectric effect AC voltage across the electrodes induces a shear deformation and

vice versa The electromechanical coupling provides a simple way to detect an acoustic resonance by

electrical means

The Z also called Z-factor is a constant value for different materials and it is shown together with the

density of different materials in table 2-2 below

Fig 2-21 QCM Crystals

The Oscillator of the SQM-160 is shown in figure 2-22 and the equivalent circuit for the Resonant

Oscillator is shown in figure 2-23

Fig 2-22 SQM-160 Oscillator

32

Fig 2-23 Oscillator Circuit

33

Table 2-2 Z-Ratios for Different Materials

Table 2-2 Continued

34

Table 2-2 Continued

35

Table 2-2 Continued

36

Table 2-2 Continued

37

Table 2-2 Continued

38

Table 2-2 Continued

235 Vacuum Chamber System

Vacuum Evaporation is the process of depositing thin films of materials onto surfaces The technique

consists of pumping a vacuum chamber to pressures of less than torr and heating a material to

produce a flux of vapor in order to deposit the material onto a surface The material to be vaporized is

typically heated until its vapor pressure is high enough to produce a flux several Angstrom per second by

using an electrically resistive heater or bombardment by a high voltage beam The process was invented

by Henri Nestle in 1886 for food industry

In here the system has been pumped to a vacuum of Torr When a high current is passed

through the filament boat the filament boat is heated over the desired metal evaporation temperature and

so evaporation starts When the evaporation process is finished and the metal cools down crystals

condensate in the surface of the wafer From the weight of the evaporated material the distance between

the filament boat and the wafer we are able to calculate the deposition thickness and we can also use the

mass detector follower like the Quartz crystal resonator microbalance system In the process of

evaporation we usually use a board in between the filament boat and the wafer This is because before we

arrive to the desired evaporation temperature there will be some impurities that will be vaporized in the

controlled environment so we first use a small current and the board in between to get rid of those

impurities and this raises the purity of the deposition material

39

A vacuum evaporation system is shown in figure 2-24

Fig 2-24 Vacuum Evaporation System

Rough Vacuum 760 ~ 1 torr

Medium Vacuum 1 ~ torr

High Vacuum ~ torr

Ultra-High Vacuum Lower than torr

Table 2-3 Classification of Vacuum

For our study we need to use a Turbo Pump A regular turbo pump is shown in figure 2-25

Fig 2-25 Turbo Pump

For our research we used the Pfeiffer TCP 015 Electronic Drive Unit and Granville Phillips 375

Convectron shown below in figure 2-26

40

Fig 2-26 Control and Measurement Equipment

The electronic drive controls the turbo pump and the Convectron measures the pressure inside our

chamber The turbo pump is a type of vacuum pump used to maintain high vacuum Most turbo pumps

are centrifugal When we start the pumping we need to use a mechanical pump so as to decrease the

pressure inside the system from constant atmospheric pressure to torr and then the use dispersion

pump to continue the vacuum until we get to the desired pressure We need to notice though when we

start the dispersion pump we canrsquot turn off the mechanical pump and they both need to run together If

we need to turn off the pumping we first turn off the dispersion pump wait for it to completely stop and

then turn off the mechanical pump

Our completely assembled system is shown in figure 2-27 below

Fig 2-27 Complete System

41

Chapter 3 TENSILE TESTING IN DEPTH

31 Experimentrsquos Purpose and Principles

By means of Universal testing machine and Strain gauges we were able to observe discuss and

analyze the phenomena created when a specimen of certain material is manipulated under an external load

and determine the stress strain and deformation values later we can use the graphing methods of

stress-strain diagram to describe it

The main point of this experiment is that after the tensile specimen is tested use computer analysis

and the actual strain data and after statistical adjustment make the final results report (Tensile testing

experiment is in accordance with ASTM E8)

32 Experimentrsquos Equipment

321 Universal Testing Machine

For the materials testing experiment part of this research we use a Universal Testing Machine as

shown in figure 31 The maximum load it can apply is 100 Ton After the test specimen is secured on the

device with the use of instrumentation the load exerted and the effects of this become apparent on the

specimen and even the smallest of changes can be recorded For our research we used the Chun Yen

Testing Machines Co Ltd 100 Ton Micro Computer Universal Tensile Tester

Fig 31 Universal Testing Machine

42

Table 31 shows the specifications for this machine

Max Capacity 100 Ton

Accuracy plusmn1

Tension (mm) Max Space 1150mm

Grip for Rod 20-70mm

Ram Stroke 250mm

Effective Column Interval 940mm

Crosshead Speed 300mmmin

Testing Speed 0-50mmmin

Volume of Machine 1700times1000times3350mm(LtimesWtimesH)

Volume of Control Panel 1000times800times1500mm(LtimesWtimesH)

Weight 8000kg

Power 3∮220V 20A

Computer AMD K6-2-350

OS Windows XP

Screen 15rdquo CRT

Table 3-1 Chun Yen Testing Machine Specs Table

The connections diagram is shown in figure 3-2

Fig 3-2 Diagram for System Connections

43

When the test specimen is placed when the external force is applied the Load Cell can measure the

size of the applied force and the Encoder measures the expansion rate of change The Local Controller

receives all the information from the 2 units after arranging the results they are displayed in the

computer and they can be afterwards submitted for more complex analysis such as Finite Element

Analysis and we can get the Stress-Strain Diagram

322 Strain Measurement Equipment

The equipment used in our research provides a four-channel measurement that means we can use up

to 4 strain gauges at a time to do our measurements and provides 3 different bridge arrangements as

shown in figure 3-3

(a) (b) (c)

Fig 3-3 Input Connections for Strain Indicator

Figure 3-3 (a) is the Quarter Bridge (b) is the Half Bridge and (c) is the Full Bridge and Transducers

For our study we used the Quarter Bridge and use the Strain Gauge values to decide the position of the

connecting wires The Strain indicator is shown in figure 3-4

Fig 3-4 Vishay Micro-Measurements Model P3 Strain Indicator and Recorder

44

Input Connections Tool Free eccentric lever release

4-channel input

Wire diameter16-28AWG

Bridge Configurations Quarter- Half- and Full Bridge

Bridge Impedance 60-2000Ω

Display 128 64 pixel FSTN positive gray LCD

Data Conversion AD Converter filter

Measurement Range Resolution Strain Range plusmn155mVV

Resolution plusmn00005mVV

Measurement Accuracy plusmn01 of reading plusmn3 counts

Gage Factor Control 0500-9900

Balance Control Software either manual or automatic

Bridge Excitation 15VDC nominal

Communication Interface USB Cable Included

Data Storage Removable Media Card

Shunt Calibration Across bridge completion resistors controlled

by software When Gage Factor=200

120Ω350Ω1000Ω

Analog Output Value 0 to 25V max

Ranges plusmn320 microε plusmn3200 microε plusmn32000 microε

Error 05 output voltage +5mV

Max Error 14 output voltage + 20mV

Update rate 480 samplessec

Output Load 2000Ω

Power Battery Two Alkaline D cells

Battery life 400 hours typ

USB 5V 100mA

Operational Environment Temperature 0-50

Humidity Up to 90 Non-condensing

Case Aluminum Alloy

Size and Weight 228times152times152(mm) 20(kg)

Table 3-2 Vishay Micro-Measurements Model P3 Strain Indicator and Recorder Specs

45

323 Strain Gauge

The strain gaugersquos main basic principle is to use a resistancersquos characteristics to measure the strain

The inside connections of the strain indicator are shown in figure 3-5

Fig 3-5 Inner Connections

As shown above this is a quarter-bridge connection We connect equal-length 3 wires to the 2

connections allowed by the strain gauge wire 1 and 3 can be used to cancel out the effects of temperature

to the resistance and because of the addition of wires 1 and 3 wire 2 can directly measure the experiment

results from the strain gauge and therefore the strain developed with no influence of temperature

If there were no two measuring leads then the relations will be

R 4 =R g +2R L

Where Rg is the Strain Gauge Value and RL is the wire resistance then

4

4

R

R=

Lg

g

RR

R

2

=

gL

gg

RR

RR

21

amp

4

4

R

R=

g

g

R

R(1- L)

Where L is the Signal Loss Factor and so

L =gL

gL

RR

RR

21

2

g

L

R

2R if

g

L

R

2Rltlt1

46

(Actual Value R g =120R L =08g

L

R

2Ris always much smaller than 1)

R 4 =R g +2R LR 2 =R 3 =rR gR 1 =R g 32 RR =0

V 0 =V 2)1( r

r

(

4

4

R

R-

1

1

R

R)

The first term describes loss attenuation effects second term describes loss of balancing capabilities

effects

V 0 =V 2)1( r

r

[

)2

(Lg

g

RR

R

+

T

Lg

g

RR

R

)

2( + T

Lg

L

RR

R

)

2

2( -(

g

g

R

R) T ]

The first term describes loss attenuation effects and loss of balancing capabilities effects the second

third and fourth terms describe the temperature effects on the wire

For the three-wire method we have

L =gL

gL

RR

RR

1

g

L

R

R if

g

L

R

Rltlt1

V 0 =V 2)1( r

r

[

)(Lg

g

RR

R

+

T

Lg

g

RR

R

)( + T

Lg

L

RR

R

)

2( -

T

Lg

g

RR

R

)( - T

Lg

L

RR

R

)

2( ]

V 0 = V2)1( r

r

)(

Lg

g

RR

R

In the last four terms inside parenthesis we can see the effects of temperature being cancelled out and the

effect on first term is not great so this is the reason why in our research we use three wires

47

324 Specimen Measurements

The tensile specimens used in this research are compliant of ASTM E8 Tensile parameters as shown

in figure 3-6

Fig 3-6 Tensile Specimen

Diameter

D(mm)

Gauge

Length

G(mm)

Smallest

Arc

Radius

R(mm)

Shortest

Area

A(mm)

Total

Length

L(mm)

Clamping

Area

Length

B(mm)

Clamping

Area

Diameter

C(mm)

Bar 125 02 625 01 gt10 gt75 ~ 145 ~ 35 20

Table 3-3 Specifications for Round Bar

33 Experiment Procedure

1 Attaching the Strain Gauge to the Tensile Specimen

(1) Prepare 1 ASTM E8 compliant tensile specimen round bar as shown in figure 3-7

(2) Prepare Strain Gauge as those described in table 3-4

(3) Prepare other consumables and adhesive agent such as epoxy adhesive or

cyanoacrylate adhesive as shown in figure 3-8

48

Fig 3-7 Actual Tensile Specimen

Fig 3-8 Other Materials Used (Such as Alcohol gauze transparent tape adhesive)

Gage Type

EA-06-120LZ-120E

Resistance in ohms at 24∘C

1200plusmn03

Gage Factor at 24∘C

2075plusmn05

Transverse Sensitivity at 24∘C

(+07plusmn02)

Table 3-4 Specifications for Strain Gauge

2 Attaching Strain Gauge

As shown in following figures we shall explain the attachment of the strain gauge

(1) Use sand paper and a rasp to clean thoroughly the surface where the strain gauge will be

attached to

49

(a)

(2) Use alcohol to wash the surface where the strain gauge will be attached and use gauze to rub

it off

(b)

(3) Find a clean surface and clean it with alcohol and gauze

(c)

(4) Place the strain gauge in the clean surface Use a piece of transparent tape on top of the strain

gauge after securely placed rip it off the surface carefully

50

(d)

(5) Use a piece of white paper to mark the place where the strain gauge will be attached and in

this way we can make sure that the strain gauge will be placed as horizontally and vertically

correct as possible

(e)

(6) In the place where we had our mark place the strain gauge

(f)

(7) Carefully lift one side of the tape and apply some of the adhesive agent to both the strain

gauge and specimenrsquos surface

(g)

51

(8) We need to make sure that the gauge and the specimen will be firmly attached so we gently

apply pressure with our thumb

(h)

(9) After the adhesive is fully dry we can carefully rip off the tape

(i)

(10) We need to do the whole process twice one for the horizontally placed strain gauge and one

for the vertically placed strain gauge

52

(j)

(11) We now proceed to solder the wires to the strain gauge

(k)

(12) After soldering we use a Volt Multimeter to measure that there is no contact between wires

If there is none then the specimen is ready for testing

(l)

(13) We now need to measure a 5cm distance and mark it to check and compare the elongation

before and after the tensile testing

(m)

53

Fig 3-9 Specimen-Strain Gauge Process

3 Tensile Test

(1) Enter the computer application that controls the tensile testing machine

(2) Turn on the tensile testing machine main switch

(3) Adjust the hydraulic pump to go back to its original position

(4) Bring the lowering motor down to a distance enough so as to attach the tensile specimen to the

system open the clamps and secure the specimen

(a)

(5) Connect all the necessary wires to the strain indicator equipment

54

(b)

(6) Start the ascending motor and wait for the expansion

(c)

Fig 3-10 Specimen-Tensile Testing Process

4 Start the Test

(1) Enter the software application and enter some variables needed for the experiment in the

specific screen

(2) Go back to the main screen and press the [測試] (measure) button to start the test and auto

recording in the software

(3) After the specimen breaks the mechanical device will automatically stop and ask the user to

enter the total displacement We take out the specimen from the testing machine and adjust the

machinersquos position back to its original position

(4) Save the results information

(5) Record the results from the strain indicator

34 Results

From this experiment we can get the Poissonrsquos Ratio Youngrsquos Modulus and Yield Strength etc and

because of the slippage phenomenon in the clamp at the moment of the test then the Elastic Limit will

display some yield phenomena So omit any undesirable results we just take the Yield portion of the

results as reference

In the process of the experiment the most important part to attend to is the attaching of the strain

gauge because the gaugersquos purpose is to measure the strain developed during the test and this strain

might be very small If the gaugersquos angle change during the test ie is not well attached this will affect

the accuracy of the measurements of Poissonrsquos ratio and Youngrsquos modulus

55

The materials provided by the manufacturer are SUM 23 and SUM 43 steel round bars and these two

types of materials have been through different heat treatment processes so they can be sub-divided

further into untreated material heat-treated material and black surface heat treated material for the two

materials with heat treatment the treatment process and finished are different In the end we only have

the mechanical properties that were calculated after our research of these materials

All of the specifications are identical to those shown in figure 3-6

341 SUM 23

Fig 3-11 SUM 23 Untreated Material

Number 7 10

Hardness(HRB) 74 75

Yield Stress (MPa) 448 440

Tensile Strength (MPa) 544 560

Poissonrsquos Ratio 029 027

Youngrsquos Modulus (GPa) 203 210

Cut-off Area Shrinking () 42 41

Elongation () 1125 1011

Table 3-5 Mechanical Properties of SUM 23 Untreated

56

Stress-Strain Diagram

(a)

(b)

57

Fig 3-12 Stress-Strain Diagrams for (a) 7 Round Bar and (b) 10 Round Bar

Cut-Off Area

(a)

(b)

Fig 3-13 Cut-Off Area of (a) 7 Round Bar and (b) 10 Round Bar

58

SUM 23 Nickel Round Bar

Fig 3-14 SUM 23 Nickel Material

Number 1 2 3 4

Hardness(HRB) 48 50 49 48

Yield Stress (MPa) 370 370 380 400

Tensile Strength (MPa) 455 451 450 450

Poissonrsquos Ratio 028 046 029 026

Youngrsquos Modulus (GPa) 243 303 246 206

Cut-off Area Shrinking () 803 803 726 601

Elongation () 566 65 602 647

Table 3-6 Mechanical Properties of SUM 23 Nickel

59

Stress-Strain Diagram

(a)

60

(b)

(c)

(d)

61

Fig 3-15 Stress-Strain Diagrams for (a) 1 Round Bar (b) 2 Round Bar (c) 3 Round Bar and (d)

4 Round Bar

Cut-Off Area

(a)

(b)

62

(c)

(d)

Fig 3-16 Cut-Off Area of (a) 1 Round Bar (b) 2 Round Bar (c) 3 Round Bar and (d) 4 Round

Bar

63

SUM 23 Black Surface Round Bar

Fig 3-17 SUM 23 Black Surface Material

Number 1 2 3

Hardness(HRB) 51 50 51

Yield Stress (MPa) 378 371 369

Tensile Strength (MPa) 467 465 464

Poissonrsquos Ratio 03 016 04

Youngrsquos Modulus (GPa) 215 266 266

Cut-off Area Shrinking () 986 94 848

Elongation () 748 805 761

Table 3-7 Mechanical Properties of SUM 23 Black Surface Material

64

Stress-Strain Diagram

(a)

(b)

65

(c)

Fig 3-18 Stress-Strain Diagrams for (a) 1 Round Bar 2 Round Bar and (c) 3 Round Bar

Cut-Off Surface

(a)

66

(b)

(c)

Fig 3-19 Cut-Off Surface of (a) 1 Round Bar 2 Round Bar and (c) 3 Round Bar

67

342 SUM 43

Fig 3-20 Untreated SUM 43 Untreated Material

Number 1 5

Hardness(HRB) 76 75

Yield Stress (MPa) 572 594

Tensile Strength (MPa) 743 785

Poissonrsquos Ratio 027 029

Youngrsquos Modulus (GPa) 200 202

Cut-off Area Shrinking () 338 2944

Elongation () 857 894

Table 3-8 Mechanical Properties of SUM 43 Untreated

68

Stress-Strain Diagrams

(a)

(b)

Fig 3-21 Stress-Strain Diagrams for SUM 43 (a) 1 Round Bar and (b) 5 Round Bar

69

Cut-Off Area

(a)

(b)

Fig 3-22 Cut-Off Area of SUM 43 (a) 1 Round Bar and (b) 5 Round Bar

70

SUM 43 Nickel Round Bar

Fig 3-23 SUM 43 Nickel Material

Number 4 5

Hardness(HRB) 51 50

Yield Stress (MPa) 1580 1544

Tensile Strength (MPa) 1639 1625

Poissonrsquos Ratio 03 028

Youngrsquos Modulus (GPa) 194 201

Cut-off Area Shrinking () 1697 137

Elongation () 376 265

Table 3-9 Mechanical Properties of SUM 43 Nickel

71

Stress-Strain Diagrams

(a)

(b)

Fig 3-24 Stress-Strain Diagrams for (a) 4 Round Bar and (b) 5 Round Bar

72

Cut-Off Area

(a)

(b)

Fig 3-25 Cut-Off Area of (a) 4 Round Bar and (b) 5 Round Bar

73

SUM 43 Black Surface Material

Fig 3-26 SUM 43 Black Surface Material

Number 3 5

Hardness(HRB) 56 56

Yield Stress (MPa) 1416 1361

Tensile Strength (MPa) 1591 1402

Poissonrsquos Ratio 029 031

Youngrsquos Modulus (GPa) 200 202

Cut-off Area Shrinking () 139 124

Elongation () 24 24

Table 3-10 Mechanical Properties of SUM 43 Black Surface Material

74

Stress-Strain Diagrams

0 2 4 6 8 10 12 14

-200

0

200

400

600

800

1000

1200

1400

1600

1800

應力 (MPa)

應變()

(a)

0 2 4 6 8 10

-200

0

200

400

600

800

1000

1200

1400

1600

應力

(MPa)

位移 ()

(b)

Fig 3-27 Stress-Strain Diagrams for (a) 3 Round Bar and (b) 5 Round Bar

(Note These curves were formulated using Visual Solutions Inc VisSim Software)

75

Cut-Off Area

(a)

(b)

Fig 3-28 Cut-Off Area of (a) 3 Round Bar and (b) 5 Round Bar

76

The force value (N) was retrieved from the Universal Testing Machine

The Poissonrsquos Ratio (ε) is calculated as

ε =

the values for the Poissonrsquos Ratio are in average around 0297

The Youngrsquos Modulus (E) is calculated as

E =

Where

Stress =

Cross-sectional Area =

where D is the Diameter

The value for D was in average around 1258 mm

The values shown by the computer because there is Slippage phenomena between the Clamp and the

specimen will not be taken into consideration for the elongation strain and Youngrsquos modulus and we will

refer to the values that we have meticulously calculated

77

Chapter 4 AR COATING IN DEPTH

41 Experimentrsquos Purpose and Principles

By means of a vacuum chamber and several other instruments we intend to apply Anti-Reflective

Coating using deposition process to a laser diode and in this way reduce its refraction so as to make it

lose less light in the process of amplification and we can control certain wavelengths we want produced

for certain desired applications in our case we are attempting to re-create a Bose-Einstein Condensate

An optimal BEC apparatus is shown in figure 4-1

Fig 4-1 BEC Apparatus

The main point of this experiment is to build a vacuum chamber system attach all the instrumentation

needed (Vacuum pump deposition meter and voltmeter) and use it to apply AR coating to a laser diode

After we have accomplished the AR coating other team will be in charge of designing the BEC apparatus

and use the results of our research

78

42 Experimentrsquos Equipment

421 Vacuum Chamber

For this research we designed a vacuum chamber whose main body is shown in figure 4-2 Its

dimensions are

Width 240 mm

Length 240 mm

Height 200 mm

Outer Diameter 4 in

Inner Diameter 15 in

Fig 4-2 Vacuum Chamber Main Body

The chamber is made up of 6 pass ways pass way A is the connection with the Laser Deposition

Equipment pass way B is the connection with the Turbo Pump and pass way C is for the connection with

the Deposition Source

A

C

B

79

Pass way C is for the deposition source as mentioned above This is a system where a thermal

resistance is heated by passing a high current through it which heats up a filament boat (made of tungsten)

where the material to be evaporated is place We control the temperature as such that the material will

evaporate and the heat will not cause the filament boat to crack

Because P = Isup2 R (where P is power I is current and R is resistance) to avoid the current to flow

where it is not desired we decided that the material for the Thermocouple shown in figure 4-3 should be

Copper ᴓ 63 mm We choose it that way because Copper has very good heat dissipation characteristics

and the resistance value is low It can reduce the value of the current enough to make the thermocouple to

create heat

Fig 4-3 Thermocouple

To the thermocouple we attach the tungsten filament boat We need to take notice of materials to be

used in this design because when using high current the tungsten filament boar will heat up and so the

material must be able to keep up with the heating potential of tungsten and has a low coefficient of heat

dissipation to avoid the tungsten to fail when heating up and therefore not evaporating Considering all

this we decide to use Stainless Steel

Because this clamp will be assembled inside the chamber after many revisions it was determined it

will have the shape shown in figure 4-4

Fig 4-4 Filament Boat Clamp Design

80

For the tungsten filament boat we bought the product from a distributor The dimensions are

Length 100 mm

Width 10 mm

Height 1 mm

Our thermocouple is 15 in but the pass way C is 4 in so we need to attach a Flange that connects

15in to 4in Because these specifications are quite difficult to achieve by Milling we had to use

electrical wire cutting

For the laser clamping system where the laser that is going to be AR coated will be placed will be

connected to pass way A the assembly is shown in figure 4-5 below

Fig 4-5 Cover Assembly

For this design we used an O-ring instead of a gasket so as to save time The design of the assembly

where the laser will be placed is shown in figure 4-6

Fig 4-6 Upper Cover Inner Assembly

D

E

F

81

Point D is the plate in the assembly where the laser diode will be fixed Because of the easy

processing we decide to use Aluminum and it is screwed to the top cover Point E is the connection for

the Quartz crystal resonator and it is designed in the same as point F in this way the results of the quartz

microbalance system will be more accurate in real time Point F is the final resting place for the laser

diode We use a Thor Labs Base with dimensions of ᴓ 9mm and ᴓ 56mm for two different size laser

diodes It just needs to be plugged in for easy installation

From figure 4-6 we know that the system needs signal system connections and because of the

change in temperature inside the chamber this could affect the functioning of the quartz microbalance so

we also need to install water tubes for cooling This is shown in figure 4-7 below

Fig 4-7 Diagram of Upper Cover Connections

In figure 4-8 we show the Feed through connections and their functions

Fig 4-8 Feed through Diagram

82

1 SQM-160 wire 5 Laser Connection 1 (Vin)

2 SQM-160 (G) 6 Laser Connection 2 (G)

3 K-Type-1 7 Laser Connection 3 (PD)

4 K-Type-2 8 Not In Use

The fully assembled chamber is shown in figure 4-9

Fig 4-9 Fully Assembled Chamber

422 Quartz Crystal Microbalance

For measuring the deposition on our target for coating we used the Inficon SQM-160 RateThickness

Monitor It is an easy to use instrument for measuring many types of thin-film coatings as shown in

figure 4-10

(a) Front Panel (b) Back Panel

Fig 4-10 Inficon SQM-160

83

Table 4-1 shows the technical specifications for this equipment

Number of sensors 2 Standard 4 additional optional

Sensor Frequency Range 40 MHz ~ 60 MHz

Reference Frequency Accuracy 002

Thickness Display Resolution 1 Aring

Thickness Resolution 015 Aring (Std) 0037 Aring (Hi Res)

Density of Stored Films 05-9999 gmcc

Tooling 10-399

Z-Factor 010-1000

Final Thickness 0000-9999k Aring

Measurement Period 15 to 2 sec

Simulation Mode Yes

Frequency Mode Yes

Rate Resolution 011 Arings

Dual Crystal Yes

Etch Mode Yes

Crystal Tooling 10-399

Crystal Fail Min Max 40 to 60 MHz 41 to 61 MHz

Power 100-120 200-240~plusmn10 nominal 20W

Operation Environment 0degC ~ 50degC

0 ~ 80 RH non-condensing

0 ~ 2000 meters

Class 1 Equipment

Pollution Degree 2

Rack Dimensions 885mm x 2127mm x 1969mm

Weight 27 kg

Table 4-1 Inficon SQM-160 RateThickness Monitor Specs

84

To the SQM-160 we need to connect an Oscillator We use the Sigma Instruments Remote Oscillator

Ser No 2 268 as shown in figure 4-11

Fig 4-11 Sigma Instruments Remote Oscillator

The connections diagram is shown in figure 4-12

Fig 4-12 SQM-160 Connections Diagram

85

423 Turbo Pump

For our experiments we used the Pfeiffer TCP 015 Electronic Drive Unit shown below in figure 4-13

Table 4-2 shows the technical specifications for this equipment

(a) Front Panel (b) Back Panel

Fig 4-13 Pfeiffer TCP 015 Electronic Drive

Connection Voltage (100V) 90-112

Mains Frequency 5060 Hz

Start-up Current 22 A

Nominal Frequency 1500 Hz

Rotation Speed 10V = 1500Hz plusmn2

Analog Output Current 10 V = 25 A plusmn 5

Rotation Speed Switchpoint 750 Hz

Works Setting 8 min

Permissible Ambient Temperature 0degC ~ 40degC

Dimensions Front Panel 1285mm x 1063mm

Insertion Length 227mm

Weight 27 Kg

Table 4-2 Pfeiffer TCP 015 Electronic Drive Specs

86

The connections diagram is shown in figure 4-14

Fig 4-14Connections Diagram for Pfeiffer TCP 015

To measure the pressure inside the chamber we use the Granville Phillips 375 Convectron Vacuum

Pressure Controller shown in figure 4-15

(a) Front Panel (b) Back Panel

Fig 4-15 Granville Phillips 375 Convectron

87

Its dimensions are shown in figure 4-16

Fig 4-16 Dimensions of Convectron

Table 4-3 shows the technical specifications for this equipment

Table 4-3 Granville Phillips 375 Convectron Vacuum Pressure Controller Specs

88

424 Multimeter

For our experiment we used the Keithley 2000 Digital Multimeter as shown in figure 4-17

(a) Front Panel (b) Back Panel

Fig 4-17 Keithley Model 2000 6-12-Digit Digital Multimeter

Its technical specifications are shown in table 4-4

Table 4-4 Keithley Model 2000 6-12-Digit Digital Multimeter Specs

89

43 Experiment Procedure

1 Connecting together the equipment and the chamber

(1) We first connect the resonator to the thickness monitor and connect the other side to the

chamber

(2) We now connect the flexible tubes to the turbo pump on one side and to the chamber on the

other

(3) We need to check that tubes are tightly connected to avoid any leaks in the vacuum pumping

process which will not allow us to get to our goal of Torr As shown in figure 4-18

(4) Connect the convectron to the system as shown in figure 4-19

Fig 4-18 checking for leaks using alcohol

Fig 4-19 Convectron attached to System

90

(5) Attach the clamps of the Multimeter to the bottom of the chamber as shown in figure 4-20

(6) Place the Quartz crystal in place

(7) Close tight vacuum chamber

(8) Connect all electrical appliances to power source

Fig 4-20 Multimeter Connections

2 Starting up the System

(1) We turn on all the devices as such Check all systems are ready to function Reset all values

that might be left over from previous tests

(2) Start the thickness monitor and set all values for this experiment In our case we got to testing

the system but not actual coating So we used the simulation mode of the thickness monitor as

shown in figure 4-21

Fig 4-21 Simulation Mode

91

(3) Start the turbo pump Make sure the lid on the vacuum chamber is tightly closed

(4) Start convectron and record initial pressure

(5) Start Multimeter and record initial current

3 Coating Process

(1) If we have the deposition material inside the filament boat the power source for the high

current must be started as well

(2) Record all initial values for thickness current pressure

(3) For an ideal experiment we need a thickness of around 101 nm a pressure of Torr and

a current of 300 A

44 Results

From previous experiments we have shown that we can turn a LED into a laser by means of AR

Coating In figure 4-22 shown below we can compare the actual results of a Diode before and after AR

coating From the blue line we can see that when the diode is at a current of 15mA its light will change

from LED to laser and if we look at the red line its critical current is around 30 to 35 mA

Fig 4-22 AR Coating Comparison for Laser Diodes

This means that the light emitted is not as strong as if the diode had been coated because inside the

chamber there must be some excitation first so the reflectivity of both sides inside the diode must be high

So because of the coating in one of the sides we have opened a door and let the light come out so the

critical current is risen as such and will be higher value than that of before the coating

92

In the following figures we can see the difference between before and after coating in a material The

thickness is around 1016 nm for this material

Fig 4-23 Before Coating

Fig 4-24 After Coating

93

Chapter 5 CONCLUSIONS AND RECOMMENDATIONS

51 Conclusions

For the first part of this independent study taking into consideration the data that came out of our

research and that sent by the provider we can say

1 SUM 23 after heat treatment will unexpectedly develop cracking in the middle of the tensile

testing process and suddenly break

2 Itrsquos possible that in the process of heat treatment to the SUM 23 material the treatment was not

uniform and this will create a pre-loaded moment force on one side that pushes on the other side

of the specimen resulting in material deformation

3 In the process of attaching the strain gauges to the materials it is very easy to make errors due to

poor adhesion or sudden removal in the tensile testing process

For our second part of the independent study the following can be made

1 At the beginning of this independent study we had no idea what Bose-Einstein Condensate was

or what was its purpose After much literature we finally comprehended the basic principles to

put into practice for our research

2 Our systemrsquos basic working principles and equipmentrsquos complexity are a little difficult to grasp

but hopefully we were able to understand enough of it

3 Theoretically from relation between the power and current we can know the advantages and

disadvantages of AR Coating

4 We were able to assemble the system and run test on its functions Even though we were able to

do this there is still much more work left to do with this system

52 Recommendations

For the Tensile Testing the following can be said

1 Ask the provider to check on the process of heat treatment on the SUM 23 material and give

them the information we have gathered through our test so they can correct for the mechanical

properties found if any change is needed

2 To avoid the problem of the inaccuracy of the poor adhesion of strain gauges we can attach

multiple strain gauges to the same one specimen so as to correlate data and improve our results

For the AR Coating the following can be said

1 We need to make sure that there are no physical defects on the main body of the chamber so as to

achieve maximum efficiency in the vacuum process If there was then the vacuum will arrive to

certain point and then start to decrease

2 It would be preferable to add some sort of visual aid that will allow the user to check the inside of

the chamber without actually opening it This will help us determine at what times we should

manipulate the current to better evaporate the substrate

94

REFERENCES

[1] A L Window Strain Gauge Technology Elsevier Applied Science London and New York 2nd

Edition 1992

[2] CC Perry and HR Lissner Strain Gauge Primer McGraw-Hill Book Co Inc New York 1955

[3] James W Dally William F Riley McGraw-Hill 1978

[4] University of Colorado Boulder BEC - What is it and where did the idea come from

httpwwwcoloradoeduphysics2000becwhat_is_ithtml

[5] Ultraslow Light amp Bose-Einstein Condensates Two-way Control with Coherent Light amp Atom

Fields Harvard Hau Lab Dr Lene Vestergaard Hau Optics amp Photonics News 16 1995

[6] The Art of Taming Light Ultra-slow and Stopped Light Harvard Hau Lab Dr Lene

Vestergaard Hau Europhysics News 2004

[7] Nonlinear Optics Shocking Superfluids Harvard Hau Lab Dr Lene Vestergaard Hau Nature

Physics 2007

[8] Model P3 Strain Indicator and Recorder Instruction Manual Vishay Micro-Measurements 2005

[9] Granville-Phillips Series 375 Convectron Vacuum Gauge Controller Instruction Manual Brooks

Automation 2008

[10] Effect of Film Thickness on the Validity of the Sauerbrey Equation for Hydrated Polyelectrolyte

Films Vogt Lin Wu White 2004

[11] Quartz Crystal Microbalance Study of DNA Immobilization and Hybridization for DNA Sensor

Development Chang Zhao 2008

[12] Installation of Strain Gages with SR-4 PrecoatAdhesive Vishay Micro-Measurements 2005

[13] Strain Gauge Measurement ndash A Tutorial National Instruments 1998

[14] Correlation between Vickers Hardness Number and Yield Stress of Cold-Formed Products

Yavuz Tekkaya

[15] httpsenwikipediaorg

Page 24: PC Hinge Materials Testing and AR Laser Diode Coating

24

Exclusion Principle only one fermion can occupy a particular quantum state at any given time If multiple

fermions have the same spatial probability distribution then at least one property of each fermion must be

different Fermions are usually associated with matter because composite fermions are key building

blocks of matter (neutrons and protons)

Fermionsrsquo behavior by the Fermi-Dirac Statistics which describes the energies of single particles in a

system comprising of many identical particles It applies to identical particles with half-odd integer spin

in a system of thermal equilibrium The particles in the system are assumed to have negligible mutual

interaction This allows the many-particle system to be described in terms of single-particle energy states

The result is the Fermi-Dirac distribution of particles over these states and includes the condition that no

two particles can occupy the same state which has considerable effect on the properties of the system

In quantum mechanics the position of an object is uncertain An object has a definite probability of

being at any given point in space This probability is encoded in the wave function mentioned earlier If

one concentrates a large number of identical bosons in a small region then it is possible for their wave

functions to overlap so much that the bosons lose their identity When this happens thatrsquos a Bose-Einstein

Condensate It is only possible at very low temperatures because at high temperatures the individual

bosons have small wave functions and move rapidly which causes them to fly apart

For now applications are still restricted because there are still some setbacks regarding BECs They

are extremely fragile they are being produced in small quantities with just a few million atoms at a time

and finally they can only be made from certain types of atoms Some examples are the atom laser Ketterle

in which a conventional light lase emits a beam of coherent photons this means they are all in phase and

can be concentrated to an extremely small bright spot BECs can slow down light as demonstrated by

Prof Lene Hau PhD in 2001 by the use of a superfluid [7] These manipulations could develop into

new types of telecommunications technology optical storage and quantum computing

BECs are related to super-fluidity and super-conductivity Super-fluidity is the state of matter in

which the behavior is that of a fluid with zero viscosity It was discovered in liquid helium but now it has

applications in astrophysics high-energy physics and theories of quantum gravity

Super-conductivity is a phenomenon of exactly zero electrical resistance and expulsion of magnetic

fields occurring in certain materials when cooled below a characteristic critical temperature A

super-conductor is shown below in figure 2-12

Fig2-12 Super Conductor

25

232 AR Coating Basic Principles

Anti-reflective (AR) coating is a type of optical coating applied to the surface of lenses and other

optical devices (in our case we planned to apply it to a laser diode) to reduce reflection This improves

the efficiency of the system since less light is lost The primary benefit is the elimination of the reflection

itself

When light the medium (glass) it will produce reflection if 100 of the light comes from the air and

enters the glass because therersquos a difference between the index of refraction some of the light will go out

and when the light is coming out of the glass into the air once again because of the difference between

index of refraction some of the light wonrsquot be able to pass through the medium

When the light makes the first trip into the glass there was a loss of about 4 in the reflection and

when the light makes the trip back outside there was another loss of about 4 so when we assume that

100 of the light interacts with the medium actually therersquos just about 92 acting (we neglect the light

absorbed by the glass around 05) To illustrate this idea please refer to figure 2-13

Fig 2-13 Simple Model for Light in Glass Medium

When we apply the AR Coating the light that enters will only have a loss of about 05 and when

making the trip back outside again only 05 of light is loss so we get the result of increasing the light

passing through up to 99 (again neglecting the light absorbed by the glass around 05) To illustrate

this idea please refer to figure 2-14

26

Fig 2-14 Simple Model for Light in Glass Medium after AR Coating

The AR Coating can reduce reflection of incoming light In the case that light hits perpendicular to

the surface of the medium the intensity of the reflection can be calculated using the Reflection

Coefficient

Where n0 and ns are the refractive indices of the first and second media respectively The value of R

varies from 0 (no reflection) to 1 (all light reflected) and is usually quoted as a percentage

Complementary to R is the transmission coefficient or Transmittance If absorption and scattering are

neglected then the value of Transmittance is always 1-R then if a beam of light with intensity I is

incident on the surface a beam of intensity RI is reflected and a beam with intensity TI is transmitted to

the medium

The optimal value is called the Optimal Index of Refraction and is described as

For glass with ns around 15 in air (n0 around 10) then the optimum refractive index will be n1 =

1225

To reduce the refraction in this case we now mean the one that is produced inside the chamber of the

Laser diode the easiest way is to apply a low reflectivity AR coating on the surface of the laser To

measure the appropriate thickness of the coating layer we can use the equations described above By

applying a coat exactly

thickness film we can assure that a certain wavelength is transmitted The

27

reflected waves from the back of the glass medium will be half a wavelength out of phase So they

interfere destructively Because all reflected waves are interfered the maximum amount of light passes

through the coating Please refer to figure 2-15 to illustrate this idea

Fig 2-15 Light Passing through AR Coat and Glass

The most common process to attain this final product is by vacuum deposition For the best coating

results we need to lower the pressure inside the vacuum system to torr

Fig 2-16 Lens without (Top) and With (Bottom) AR Coating

28

233 Laser Diode Basic Principles

A laser diode is a laser whose active medium is a semiconductor similar to that found in

light-emitting diodes (LEDs) Please refer to figure 2-17 The most common type of laser diode is formed

from a p-n junction and powered by injected electric current

Fig 2-17 Laser Diode

Laser diodes are formed by doping a very thin layer on the surface of a crystal wafer The crystal is

doped to produce the n-type region and a p-type region one above the other

By referring to figure 1-2 we can see the basic structure of a working laser When the laser diode has

a current passing through it the light will get excited inside its gain medium and then will start to

resonate this process is called pumping The current exceeds the critical current and then it comes out as

laser light Please refer to figure 1-3 Since we use an external cavity laser we need to apply the AR

coating to the diode and adjust a diffraction grating The laser light comes out the diode and bounces on

the grating making the resonance externally and this becomes the ldquocavityrdquo as shown in figure 2-18

Fig 2-18 Tunable Laser Basic Configuration

29

The most important feature of the external cavity laser is that we can adjust the wavelength easily just

by changing the diffraction gratingrsquos angle and in the end this is the output wavelength of the laser For

different wavelengths there will be different levels of visible light as shown in figure 2-19

Fig 2-19 Light Spectrum

234 Quartz Microbalance System

A Quartz Crystal Microbalance is an instrument that measures a mass per unit area by measuring the

change in frequency of a quartz crystal resonator The resonance is disturbed by the addition or removal

of a small mass due to oxide growthdecay or film deposition (which is the case in our study) at the

surface of the acoustic resonator The QCM can be used under vacuum in gas phase and more recently in

liquid environments It is useful for monitoring the rate of deposition in thin film deposition systems

under vacuum Frequency measurements are easily made with high precision

For our research we used the Sigma Instruments SQM-160 RateThickness Monitor shown in figure

2-20

Fig 2-20 Front and Back Panels of SQM-160

30

The microbalance uses Quartz as the resonator Quartz is one member of the family of crystals that

experience the Piezoelectric Effect

Piezoelectricity is the charge that accumulates in certain solid materials in response to applied

mechanical stress It means electricity resulting from pressure It was discovered in 1880 by Jacques and

Pierre Curie It is understood as the linear electromechanical interaction between the mechanical and the

electrical state in crystalline materials with no inversion symmetry It is a reversible process in that

materials exhibiting direct piezoelectricity also exhibit the reverse This means that the internal generation

of electrical resulting from applied mechanical force and vice versa

By using the piezoelectric effect we can probe as an acoustic resonance by electrical means Applying

alternating current to the quartz crystal induces oscillations This creates a shear wave We can use these

qualities to determine the resonance frequency at high accuracy

The frequency of oscillation of the crystal is partially dependent in the thickness of the crystal During

normal operation all the variables are held constant so a change in thickness correlates directly to a

change in frequency As mass is deposited or etched away the thickness increases or decreases and so the

frequency of oscillation changes accordingly With some simplifying assumptions the frequency change

can be quantified and correlated precisely to the mass change using the Sauerbreyrsquos Equation

Developed by G Sauerbrey in 1959 it is a method for correlating changes in the oscillation

frequency of a piezoelectric crystal with the mass deposited on it It is defined as below

Where f0 is the Resonant frequency Δf is the Frequency change Δm is the mass change A is the

piezoelectrically active area of the crystal q is the Density of quartz (2648 gcmsup3) and μq is the Shear

modulus of quarts(2947x gcmssup2)

Because the film is treated as an extension of thickness Sauerbreyrsquos equation only applies to systems

in which the following 3 conditions are met

Deposited mass must be rigid

Deposited mass must be distributed evenly

The frequency change

lt002

If the change is greater than 2 the Z-match method must be used to determine the change in mass

It is defined as

Where fL is the frequency of the loaded crystal fU is the resonant frequency Nq is the frequency

constant (1668x HzAring) Δm is the mass change A is the piezoelectrically active area of the crystal

31

q is the density of quartz Z is the method constant f is the density of film μq Is the shear modulus of

quarts and μf is the shear modulus of film

The Sauerbrey equation cannot be applied to systems under liquid medium

The crystals are seed crystals plated with gold on both top and bottom for applications A crystal is

shown in figure 2-21 The QCM consists of a thin piezoelectric plate with electrodes evaporated on both

sides Due to the piezoelectric effect AC voltage across the electrodes induces a shear deformation and

vice versa The electromechanical coupling provides a simple way to detect an acoustic resonance by

electrical means

The Z also called Z-factor is a constant value for different materials and it is shown together with the

density of different materials in table 2-2 below

Fig 2-21 QCM Crystals

The Oscillator of the SQM-160 is shown in figure 2-22 and the equivalent circuit for the Resonant

Oscillator is shown in figure 2-23

Fig 2-22 SQM-160 Oscillator

32

Fig 2-23 Oscillator Circuit

33

Table 2-2 Z-Ratios for Different Materials

Table 2-2 Continued

34

Table 2-2 Continued

35

Table 2-2 Continued

36

Table 2-2 Continued

37

Table 2-2 Continued

38

Table 2-2 Continued

235 Vacuum Chamber System

Vacuum Evaporation is the process of depositing thin films of materials onto surfaces The technique

consists of pumping a vacuum chamber to pressures of less than torr and heating a material to

produce a flux of vapor in order to deposit the material onto a surface The material to be vaporized is

typically heated until its vapor pressure is high enough to produce a flux several Angstrom per second by

using an electrically resistive heater or bombardment by a high voltage beam The process was invented

by Henri Nestle in 1886 for food industry

In here the system has been pumped to a vacuum of Torr When a high current is passed

through the filament boat the filament boat is heated over the desired metal evaporation temperature and

so evaporation starts When the evaporation process is finished and the metal cools down crystals

condensate in the surface of the wafer From the weight of the evaporated material the distance between

the filament boat and the wafer we are able to calculate the deposition thickness and we can also use the

mass detector follower like the Quartz crystal resonator microbalance system In the process of

evaporation we usually use a board in between the filament boat and the wafer This is because before we

arrive to the desired evaporation temperature there will be some impurities that will be vaporized in the

controlled environment so we first use a small current and the board in between to get rid of those

impurities and this raises the purity of the deposition material

39

A vacuum evaporation system is shown in figure 2-24

Fig 2-24 Vacuum Evaporation System

Rough Vacuum 760 ~ 1 torr

Medium Vacuum 1 ~ torr

High Vacuum ~ torr

Ultra-High Vacuum Lower than torr

Table 2-3 Classification of Vacuum

For our study we need to use a Turbo Pump A regular turbo pump is shown in figure 2-25

Fig 2-25 Turbo Pump

For our research we used the Pfeiffer TCP 015 Electronic Drive Unit and Granville Phillips 375

Convectron shown below in figure 2-26

40

Fig 2-26 Control and Measurement Equipment

The electronic drive controls the turbo pump and the Convectron measures the pressure inside our

chamber The turbo pump is a type of vacuum pump used to maintain high vacuum Most turbo pumps

are centrifugal When we start the pumping we need to use a mechanical pump so as to decrease the

pressure inside the system from constant atmospheric pressure to torr and then the use dispersion

pump to continue the vacuum until we get to the desired pressure We need to notice though when we

start the dispersion pump we canrsquot turn off the mechanical pump and they both need to run together If

we need to turn off the pumping we first turn off the dispersion pump wait for it to completely stop and

then turn off the mechanical pump

Our completely assembled system is shown in figure 2-27 below

Fig 2-27 Complete System

41

Chapter 3 TENSILE TESTING IN DEPTH

31 Experimentrsquos Purpose and Principles

By means of Universal testing machine and Strain gauges we were able to observe discuss and

analyze the phenomena created when a specimen of certain material is manipulated under an external load

and determine the stress strain and deformation values later we can use the graphing methods of

stress-strain diagram to describe it

The main point of this experiment is that after the tensile specimen is tested use computer analysis

and the actual strain data and after statistical adjustment make the final results report (Tensile testing

experiment is in accordance with ASTM E8)

32 Experimentrsquos Equipment

321 Universal Testing Machine

For the materials testing experiment part of this research we use a Universal Testing Machine as

shown in figure 31 The maximum load it can apply is 100 Ton After the test specimen is secured on the

device with the use of instrumentation the load exerted and the effects of this become apparent on the

specimen and even the smallest of changes can be recorded For our research we used the Chun Yen

Testing Machines Co Ltd 100 Ton Micro Computer Universal Tensile Tester

Fig 31 Universal Testing Machine

42

Table 31 shows the specifications for this machine

Max Capacity 100 Ton

Accuracy plusmn1

Tension (mm) Max Space 1150mm

Grip for Rod 20-70mm

Ram Stroke 250mm

Effective Column Interval 940mm

Crosshead Speed 300mmmin

Testing Speed 0-50mmmin

Volume of Machine 1700times1000times3350mm(LtimesWtimesH)

Volume of Control Panel 1000times800times1500mm(LtimesWtimesH)

Weight 8000kg

Power 3∮220V 20A

Computer AMD K6-2-350

OS Windows XP

Screen 15rdquo CRT

Table 3-1 Chun Yen Testing Machine Specs Table

The connections diagram is shown in figure 3-2

Fig 3-2 Diagram for System Connections

43

When the test specimen is placed when the external force is applied the Load Cell can measure the

size of the applied force and the Encoder measures the expansion rate of change The Local Controller

receives all the information from the 2 units after arranging the results they are displayed in the

computer and they can be afterwards submitted for more complex analysis such as Finite Element

Analysis and we can get the Stress-Strain Diagram

322 Strain Measurement Equipment

The equipment used in our research provides a four-channel measurement that means we can use up

to 4 strain gauges at a time to do our measurements and provides 3 different bridge arrangements as

shown in figure 3-3

(a) (b) (c)

Fig 3-3 Input Connections for Strain Indicator

Figure 3-3 (a) is the Quarter Bridge (b) is the Half Bridge and (c) is the Full Bridge and Transducers

For our study we used the Quarter Bridge and use the Strain Gauge values to decide the position of the

connecting wires The Strain indicator is shown in figure 3-4

Fig 3-4 Vishay Micro-Measurements Model P3 Strain Indicator and Recorder

44

Input Connections Tool Free eccentric lever release

4-channel input

Wire diameter16-28AWG

Bridge Configurations Quarter- Half- and Full Bridge

Bridge Impedance 60-2000Ω

Display 128 64 pixel FSTN positive gray LCD

Data Conversion AD Converter filter

Measurement Range Resolution Strain Range plusmn155mVV

Resolution plusmn00005mVV

Measurement Accuracy plusmn01 of reading plusmn3 counts

Gage Factor Control 0500-9900

Balance Control Software either manual or automatic

Bridge Excitation 15VDC nominal

Communication Interface USB Cable Included

Data Storage Removable Media Card

Shunt Calibration Across bridge completion resistors controlled

by software When Gage Factor=200

120Ω350Ω1000Ω

Analog Output Value 0 to 25V max

Ranges plusmn320 microε plusmn3200 microε plusmn32000 microε

Error 05 output voltage +5mV

Max Error 14 output voltage + 20mV

Update rate 480 samplessec

Output Load 2000Ω

Power Battery Two Alkaline D cells

Battery life 400 hours typ

USB 5V 100mA

Operational Environment Temperature 0-50

Humidity Up to 90 Non-condensing

Case Aluminum Alloy

Size and Weight 228times152times152(mm) 20(kg)

Table 3-2 Vishay Micro-Measurements Model P3 Strain Indicator and Recorder Specs

45

323 Strain Gauge

The strain gaugersquos main basic principle is to use a resistancersquos characteristics to measure the strain

The inside connections of the strain indicator are shown in figure 3-5

Fig 3-5 Inner Connections

As shown above this is a quarter-bridge connection We connect equal-length 3 wires to the 2

connections allowed by the strain gauge wire 1 and 3 can be used to cancel out the effects of temperature

to the resistance and because of the addition of wires 1 and 3 wire 2 can directly measure the experiment

results from the strain gauge and therefore the strain developed with no influence of temperature

If there were no two measuring leads then the relations will be

R 4 =R g +2R L

Where Rg is the Strain Gauge Value and RL is the wire resistance then

4

4

R

R=

Lg

g

RR

R

2

=

gL

gg

RR

RR

21

amp

4

4

R

R=

g

g

R

R(1- L)

Where L is the Signal Loss Factor and so

L =gL

gL

RR

RR

21

2

g

L

R

2R if

g

L

R

2Rltlt1

46

(Actual Value R g =120R L =08g

L

R

2Ris always much smaller than 1)

R 4 =R g +2R LR 2 =R 3 =rR gR 1 =R g 32 RR =0

V 0 =V 2)1( r

r

(

4

4

R

R-

1

1

R

R)

The first term describes loss attenuation effects second term describes loss of balancing capabilities

effects

V 0 =V 2)1( r

r

[

)2

(Lg

g

RR

R

+

T

Lg

g

RR

R

)

2( + T

Lg

L

RR

R

)

2

2( -(

g

g

R

R) T ]

The first term describes loss attenuation effects and loss of balancing capabilities effects the second

third and fourth terms describe the temperature effects on the wire

For the three-wire method we have

L =gL

gL

RR

RR

1

g

L

R

R if

g

L

R

Rltlt1

V 0 =V 2)1( r

r

[

)(Lg

g

RR

R

+

T

Lg

g

RR

R

)( + T

Lg

L

RR

R

)

2( -

T

Lg

g

RR

R

)( - T

Lg

L

RR

R

)

2( ]

V 0 = V2)1( r

r

)(

Lg

g

RR

R

In the last four terms inside parenthesis we can see the effects of temperature being cancelled out and the

effect on first term is not great so this is the reason why in our research we use three wires

47

324 Specimen Measurements

The tensile specimens used in this research are compliant of ASTM E8 Tensile parameters as shown

in figure 3-6

Fig 3-6 Tensile Specimen

Diameter

D(mm)

Gauge

Length

G(mm)

Smallest

Arc

Radius

R(mm)

Shortest

Area

A(mm)

Total

Length

L(mm)

Clamping

Area

Length

B(mm)

Clamping

Area

Diameter

C(mm)

Bar 125 02 625 01 gt10 gt75 ~ 145 ~ 35 20

Table 3-3 Specifications for Round Bar

33 Experiment Procedure

1 Attaching the Strain Gauge to the Tensile Specimen

(1) Prepare 1 ASTM E8 compliant tensile specimen round bar as shown in figure 3-7

(2) Prepare Strain Gauge as those described in table 3-4

(3) Prepare other consumables and adhesive agent such as epoxy adhesive or

cyanoacrylate adhesive as shown in figure 3-8

48

Fig 3-7 Actual Tensile Specimen

Fig 3-8 Other Materials Used (Such as Alcohol gauze transparent tape adhesive)

Gage Type

EA-06-120LZ-120E

Resistance in ohms at 24∘C

1200plusmn03

Gage Factor at 24∘C

2075plusmn05

Transverse Sensitivity at 24∘C

(+07plusmn02)

Table 3-4 Specifications for Strain Gauge

2 Attaching Strain Gauge

As shown in following figures we shall explain the attachment of the strain gauge

(1) Use sand paper and a rasp to clean thoroughly the surface where the strain gauge will be

attached to

49

(a)

(2) Use alcohol to wash the surface where the strain gauge will be attached and use gauze to rub

it off

(b)

(3) Find a clean surface and clean it with alcohol and gauze

(c)

(4) Place the strain gauge in the clean surface Use a piece of transparent tape on top of the strain

gauge after securely placed rip it off the surface carefully

50

(d)

(5) Use a piece of white paper to mark the place where the strain gauge will be attached and in

this way we can make sure that the strain gauge will be placed as horizontally and vertically

correct as possible

(e)

(6) In the place where we had our mark place the strain gauge

(f)

(7) Carefully lift one side of the tape and apply some of the adhesive agent to both the strain

gauge and specimenrsquos surface

(g)

51

(8) We need to make sure that the gauge and the specimen will be firmly attached so we gently

apply pressure with our thumb

(h)

(9) After the adhesive is fully dry we can carefully rip off the tape

(i)

(10) We need to do the whole process twice one for the horizontally placed strain gauge and one

for the vertically placed strain gauge

52

(j)

(11) We now proceed to solder the wires to the strain gauge

(k)

(12) After soldering we use a Volt Multimeter to measure that there is no contact between wires

If there is none then the specimen is ready for testing

(l)

(13) We now need to measure a 5cm distance and mark it to check and compare the elongation

before and after the tensile testing

(m)

53

Fig 3-9 Specimen-Strain Gauge Process

3 Tensile Test

(1) Enter the computer application that controls the tensile testing machine

(2) Turn on the tensile testing machine main switch

(3) Adjust the hydraulic pump to go back to its original position

(4) Bring the lowering motor down to a distance enough so as to attach the tensile specimen to the

system open the clamps and secure the specimen

(a)

(5) Connect all the necessary wires to the strain indicator equipment

54

(b)

(6) Start the ascending motor and wait for the expansion

(c)

Fig 3-10 Specimen-Tensile Testing Process

4 Start the Test

(1) Enter the software application and enter some variables needed for the experiment in the

specific screen

(2) Go back to the main screen and press the [測試] (measure) button to start the test and auto

recording in the software

(3) After the specimen breaks the mechanical device will automatically stop and ask the user to

enter the total displacement We take out the specimen from the testing machine and adjust the

machinersquos position back to its original position

(4) Save the results information

(5) Record the results from the strain indicator

34 Results

From this experiment we can get the Poissonrsquos Ratio Youngrsquos Modulus and Yield Strength etc and

because of the slippage phenomenon in the clamp at the moment of the test then the Elastic Limit will

display some yield phenomena So omit any undesirable results we just take the Yield portion of the

results as reference

In the process of the experiment the most important part to attend to is the attaching of the strain

gauge because the gaugersquos purpose is to measure the strain developed during the test and this strain

might be very small If the gaugersquos angle change during the test ie is not well attached this will affect

the accuracy of the measurements of Poissonrsquos ratio and Youngrsquos modulus

55

The materials provided by the manufacturer are SUM 23 and SUM 43 steel round bars and these two

types of materials have been through different heat treatment processes so they can be sub-divided

further into untreated material heat-treated material and black surface heat treated material for the two

materials with heat treatment the treatment process and finished are different In the end we only have

the mechanical properties that were calculated after our research of these materials

All of the specifications are identical to those shown in figure 3-6

341 SUM 23

Fig 3-11 SUM 23 Untreated Material

Number 7 10

Hardness(HRB) 74 75

Yield Stress (MPa) 448 440

Tensile Strength (MPa) 544 560

Poissonrsquos Ratio 029 027

Youngrsquos Modulus (GPa) 203 210

Cut-off Area Shrinking () 42 41

Elongation () 1125 1011

Table 3-5 Mechanical Properties of SUM 23 Untreated

56

Stress-Strain Diagram

(a)

(b)

57

Fig 3-12 Stress-Strain Diagrams for (a) 7 Round Bar and (b) 10 Round Bar

Cut-Off Area

(a)

(b)

Fig 3-13 Cut-Off Area of (a) 7 Round Bar and (b) 10 Round Bar

58

SUM 23 Nickel Round Bar

Fig 3-14 SUM 23 Nickel Material

Number 1 2 3 4

Hardness(HRB) 48 50 49 48

Yield Stress (MPa) 370 370 380 400

Tensile Strength (MPa) 455 451 450 450

Poissonrsquos Ratio 028 046 029 026

Youngrsquos Modulus (GPa) 243 303 246 206

Cut-off Area Shrinking () 803 803 726 601

Elongation () 566 65 602 647

Table 3-6 Mechanical Properties of SUM 23 Nickel

59

Stress-Strain Diagram

(a)

60

(b)

(c)

(d)

61

Fig 3-15 Stress-Strain Diagrams for (a) 1 Round Bar (b) 2 Round Bar (c) 3 Round Bar and (d)

4 Round Bar

Cut-Off Area

(a)

(b)

62

(c)

(d)

Fig 3-16 Cut-Off Area of (a) 1 Round Bar (b) 2 Round Bar (c) 3 Round Bar and (d) 4 Round

Bar

63

SUM 23 Black Surface Round Bar

Fig 3-17 SUM 23 Black Surface Material

Number 1 2 3

Hardness(HRB) 51 50 51

Yield Stress (MPa) 378 371 369

Tensile Strength (MPa) 467 465 464

Poissonrsquos Ratio 03 016 04

Youngrsquos Modulus (GPa) 215 266 266

Cut-off Area Shrinking () 986 94 848

Elongation () 748 805 761

Table 3-7 Mechanical Properties of SUM 23 Black Surface Material

64

Stress-Strain Diagram

(a)

(b)

65

(c)

Fig 3-18 Stress-Strain Diagrams for (a) 1 Round Bar 2 Round Bar and (c) 3 Round Bar

Cut-Off Surface

(a)

66

(b)

(c)

Fig 3-19 Cut-Off Surface of (a) 1 Round Bar 2 Round Bar and (c) 3 Round Bar

67

342 SUM 43

Fig 3-20 Untreated SUM 43 Untreated Material

Number 1 5

Hardness(HRB) 76 75

Yield Stress (MPa) 572 594

Tensile Strength (MPa) 743 785

Poissonrsquos Ratio 027 029

Youngrsquos Modulus (GPa) 200 202

Cut-off Area Shrinking () 338 2944

Elongation () 857 894

Table 3-8 Mechanical Properties of SUM 43 Untreated

68

Stress-Strain Diagrams

(a)

(b)

Fig 3-21 Stress-Strain Diagrams for SUM 43 (a) 1 Round Bar and (b) 5 Round Bar

69

Cut-Off Area

(a)

(b)

Fig 3-22 Cut-Off Area of SUM 43 (a) 1 Round Bar and (b) 5 Round Bar

70

SUM 43 Nickel Round Bar

Fig 3-23 SUM 43 Nickel Material

Number 4 5

Hardness(HRB) 51 50

Yield Stress (MPa) 1580 1544

Tensile Strength (MPa) 1639 1625

Poissonrsquos Ratio 03 028

Youngrsquos Modulus (GPa) 194 201

Cut-off Area Shrinking () 1697 137

Elongation () 376 265

Table 3-9 Mechanical Properties of SUM 43 Nickel

71

Stress-Strain Diagrams

(a)

(b)

Fig 3-24 Stress-Strain Diagrams for (a) 4 Round Bar and (b) 5 Round Bar

72

Cut-Off Area

(a)

(b)

Fig 3-25 Cut-Off Area of (a) 4 Round Bar and (b) 5 Round Bar

73

SUM 43 Black Surface Material

Fig 3-26 SUM 43 Black Surface Material

Number 3 5

Hardness(HRB) 56 56

Yield Stress (MPa) 1416 1361

Tensile Strength (MPa) 1591 1402

Poissonrsquos Ratio 029 031

Youngrsquos Modulus (GPa) 200 202

Cut-off Area Shrinking () 139 124

Elongation () 24 24

Table 3-10 Mechanical Properties of SUM 43 Black Surface Material

74

Stress-Strain Diagrams

0 2 4 6 8 10 12 14

-200

0

200

400

600

800

1000

1200

1400

1600

1800

應力 (MPa)

應變()

(a)

0 2 4 6 8 10

-200

0

200

400

600

800

1000

1200

1400

1600

應力

(MPa)

位移 ()

(b)

Fig 3-27 Stress-Strain Diagrams for (a) 3 Round Bar and (b) 5 Round Bar

(Note These curves were formulated using Visual Solutions Inc VisSim Software)

75

Cut-Off Area

(a)

(b)

Fig 3-28 Cut-Off Area of (a) 3 Round Bar and (b) 5 Round Bar

76

The force value (N) was retrieved from the Universal Testing Machine

The Poissonrsquos Ratio (ε) is calculated as

ε =

the values for the Poissonrsquos Ratio are in average around 0297

The Youngrsquos Modulus (E) is calculated as

E =

Where

Stress =

Cross-sectional Area =

where D is the Diameter

The value for D was in average around 1258 mm

The values shown by the computer because there is Slippage phenomena between the Clamp and the

specimen will not be taken into consideration for the elongation strain and Youngrsquos modulus and we will

refer to the values that we have meticulously calculated

77

Chapter 4 AR COATING IN DEPTH

41 Experimentrsquos Purpose and Principles

By means of a vacuum chamber and several other instruments we intend to apply Anti-Reflective

Coating using deposition process to a laser diode and in this way reduce its refraction so as to make it

lose less light in the process of amplification and we can control certain wavelengths we want produced

for certain desired applications in our case we are attempting to re-create a Bose-Einstein Condensate

An optimal BEC apparatus is shown in figure 4-1

Fig 4-1 BEC Apparatus

The main point of this experiment is to build a vacuum chamber system attach all the instrumentation

needed (Vacuum pump deposition meter and voltmeter) and use it to apply AR coating to a laser diode

After we have accomplished the AR coating other team will be in charge of designing the BEC apparatus

and use the results of our research

78

42 Experimentrsquos Equipment

421 Vacuum Chamber

For this research we designed a vacuum chamber whose main body is shown in figure 4-2 Its

dimensions are

Width 240 mm

Length 240 mm

Height 200 mm

Outer Diameter 4 in

Inner Diameter 15 in

Fig 4-2 Vacuum Chamber Main Body

The chamber is made up of 6 pass ways pass way A is the connection with the Laser Deposition

Equipment pass way B is the connection with the Turbo Pump and pass way C is for the connection with

the Deposition Source

A

C

B

79

Pass way C is for the deposition source as mentioned above This is a system where a thermal

resistance is heated by passing a high current through it which heats up a filament boat (made of tungsten)

where the material to be evaporated is place We control the temperature as such that the material will

evaporate and the heat will not cause the filament boat to crack

Because P = Isup2 R (where P is power I is current and R is resistance) to avoid the current to flow

where it is not desired we decided that the material for the Thermocouple shown in figure 4-3 should be

Copper ᴓ 63 mm We choose it that way because Copper has very good heat dissipation characteristics

and the resistance value is low It can reduce the value of the current enough to make the thermocouple to

create heat

Fig 4-3 Thermocouple

To the thermocouple we attach the tungsten filament boat We need to take notice of materials to be

used in this design because when using high current the tungsten filament boar will heat up and so the

material must be able to keep up with the heating potential of tungsten and has a low coefficient of heat

dissipation to avoid the tungsten to fail when heating up and therefore not evaporating Considering all

this we decide to use Stainless Steel

Because this clamp will be assembled inside the chamber after many revisions it was determined it

will have the shape shown in figure 4-4

Fig 4-4 Filament Boat Clamp Design

80

For the tungsten filament boat we bought the product from a distributor The dimensions are

Length 100 mm

Width 10 mm

Height 1 mm

Our thermocouple is 15 in but the pass way C is 4 in so we need to attach a Flange that connects

15in to 4in Because these specifications are quite difficult to achieve by Milling we had to use

electrical wire cutting

For the laser clamping system where the laser that is going to be AR coated will be placed will be

connected to pass way A the assembly is shown in figure 4-5 below

Fig 4-5 Cover Assembly

For this design we used an O-ring instead of a gasket so as to save time The design of the assembly

where the laser will be placed is shown in figure 4-6

Fig 4-6 Upper Cover Inner Assembly

D

E

F

81

Point D is the plate in the assembly where the laser diode will be fixed Because of the easy

processing we decide to use Aluminum and it is screwed to the top cover Point E is the connection for

the Quartz crystal resonator and it is designed in the same as point F in this way the results of the quartz

microbalance system will be more accurate in real time Point F is the final resting place for the laser

diode We use a Thor Labs Base with dimensions of ᴓ 9mm and ᴓ 56mm for two different size laser

diodes It just needs to be plugged in for easy installation

From figure 4-6 we know that the system needs signal system connections and because of the

change in temperature inside the chamber this could affect the functioning of the quartz microbalance so

we also need to install water tubes for cooling This is shown in figure 4-7 below

Fig 4-7 Diagram of Upper Cover Connections

In figure 4-8 we show the Feed through connections and their functions

Fig 4-8 Feed through Diagram

82

1 SQM-160 wire 5 Laser Connection 1 (Vin)

2 SQM-160 (G) 6 Laser Connection 2 (G)

3 K-Type-1 7 Laser Connection 3 (PD)

4 K-Type-2 8 Not In Use

The fully assembled chamber is shown in figure 4-9

Fig 4-9 Fully Assembled Chamber

422 Quartz Crystal Microbalance

For measuring the deposition on our target for coating we used the Inficon SQM-160 RateThickness

Monitor It is an easy to use instrument for measuring many types of thin-film coatings as shown in

figure 4-10

(a) Front Panel (b) Back Panel

Fig 4-10 Inficon SQM-160

83

Table 4-1 shows the technical specifications for this equipment

Number of sensors 2 Standard 4 additional optional

Sensor Frequency Range 40 MHz ~ 60 MHz

Reference Frequency Accuracy 002

Thickness Display Resolution 1 Aring

Thickness Resolution 015 Aring (Std) 0037 Aring (Hi Res)

Density of Stored Films 05-9999 gmcc

Tooling 10-399

Z-Factor 010-1000

Final Thickness 0000-9999k Aring

Measurement Period 15 to 2 sec

Simulation Mode Yes

Frequency Mode Yes

Rate Resolution 011 Arings

Dual Crystal Yes

Etch Mode Yes

Crystal Tooling 10-399

Crystal Fail Min Max 40 to 60 MHz 41 to 61 MHz

Power 100-120 200-240~plusmn10 nominal 20W

Operation Environment 0degC ~ 50degC

0 ~ 80 RH non-condensing

0 ~ 2000 meters

Class 1 Equipment

Pollution Degree 2

Rack Dimensions 885mm x 2127mm x 1969mm

Weight 27 kg

Table 4-1 Inficon SQM-160 RateThickness Monitor Specs

84

To the SQM-160 we need to connect an Oscillator We use the Sigma Instruments Remote Oscillator

Ser No 2 268 as shown in figure 4-11

Fig 4-11 Sigma Instruments Remote Oscillator

The connections diagram is shown in figure 4-12

Fig 4-12 SQM-160 Connections Diagram

85

423 Turbo Pump

For our experiments we used the Pfeiffer TCP 015 Electronic Drive Unit shown below in figure 4-13

Table 4-2 shows the technical specifications for this equipment

(a) Front Panel (b) Back Panel

Fig 4-13 Pfeiffer TCP 015 Electronic Drive

Connection Voltage (100V) 90-112

Mains Frequency 5060 Hz

Start-up Current 22 A

Nominal Frequency 1500 Hz

Rotation Speed 10V = 1500Hz plusmn2

Analog Output Current 10 V = 25 A plusmn 5

Rotation Speed Switchpoint 750 Hz

Works Setting 8 min

Permissible Ambient Temperature 0degC ~ 40degC

Dimensions Front Panel 1285mm x 1063mm

Insertion Length 227mm

Weight 27 Kg

Table 4-2 Pfeiffer TCP 015 Electronic Drive Specs

86

The connections diagram is shown in figure 4-14

Fig 4-14Connections Diagram for Pfeiffer TCP 015

To measure the pressure inside the chamber we use the Granville Phillips 375 Convectron Vacuum

Pressure Controller shown in figure 4-15

(a) Front Panel (b) Back Panel

Fig 4-15 Granville Phillips 375 Convectron

87

Its dimensions are shown in figure 4-16

Fig 4-16 Dimensions of Convectron

Table 4-3 shows the technical specifications for this equipment

Table 4-3 Granville Phillips 375 Convectron Vacuum Pressure Controller Specs

88

424 Multimeter

For our experiment we used the Keithley 2000 Digital Multimeter as shown in figure 4-17

(a) Front Panel (b) Back Panel

Fig 4-17 Keithley Model 2000 6-12-Digit Digital Multimeter

Its technical specifications are shown in table 4-4

Table 4-4 Keithley Model 2000 6-12-Digit Digital Multimeter Specs

89

43 Experiment Procedure

1 Connecting together the equipment and the chamber

(1) We first connect the resonator to the thickness monitor and connect the other side to the

chamber

(2) We now connect the flexible tubes to the turbo pump on one side and to the chamber on the

other

(3) We need to check that tubes are tightly connected to avoid any leaks in the vacuum pumping

process which will not allow us to get to our goal of Torr As shown in figure 4-18

(4) Connect the convectron to the system as shown in figure 4-19

Fig 4-18 checking for leaks using alcohol

Fig 4-19 Convectron attached to System

90

(5) Attach the clamps of the Multimeter to the bottom of the chamber as shown in figure 4-20

(6) Place the Quartz crystal in place

(7) Close tight vacuum chamber

(8) Connect all electrical appliances to power source

Fig 4-20 Multimeter Connections

2 Starting up the System

(1) We turn on all the devices as such Check all systems are ready to function Reset all values

that might be left over from previous tests

(2) Start the thickness monitor and set all values for this experiment In our case we got to testing

the system but not actual coating So we used the simulation mode of the thickness monitor as

shown in figure 4-21

Fig 4-21 Simulation Mode

91

(3) Start the turbo pump Make sure the lid on the vacuum chamber is tightly closed

(4) Start convectron and record initial pressure

(5) Start Multimeter and record initial current

3 Coating Process

(1) If we have the deposition material inside the filament boat the power source for the high

current must be started as well

(2) Record all initial values for thickness current pressure

(3) For an ideal experiment we need a thickness of around 101 nm a pressure of Torr and

a current of 300 A

44 Results

From previous experiments we have shown that we can turn a LED into a laser by means of AR

Coating In figure 4-22 shown below we can compare the actual results of a Diode before and after AR

coating From the blue line we can see that when the diode is at a current of 15mA its light will change

from LED to laser and if we look at the red line its critical current is around 30 to 35 mA

Fig 4-22 AR Coating Comparison for Laser Diodes

This means that the light emitted is not as strong as if the diode had been coated because inside the

chamber there must be some excitation first so the reflectivity of both sides inside the diode must be high

So because of the coating in one of the sides we have opened a door and let the light come out so the

critical current is risen as such and will be higher value than that of before the coating

92

In the following figures we can see the difference between before and after coating in a material The

thickness is around 1016 nm for this material

Fig 4-23 Before Coating

Fig 4-24 After Coating

93

Chapter 5 CONCLUSIONS AND RECOMMENDATIONS

51 Conclusions

For the first part of this independent study taking into consideration the data that came out of our

research and that sent by the provider we can say

1 SUM 23 after heat treatment will unexpectedly develop cracking in the middle of the tensile

testing process and suddenly break

2 Itrsquos possible that in the process of heat treatment to the SUM 23 material the treatment was not

uniform and this will create a pre-loaded moment force on one side that pushes on the other side

of the specimen resulting in material deformation

3 In the process of attaching the strain gauges to the materials it is very easy to make errors due to

poor adhesion or sudden removal in the tensile testing process

For our second part of the independent study the following can be made

1 At the beginning of this independent study we had no idea what Bose-Einstein Condensate was

or what was its purpose After much literature we finally comprehended the basic principles to

put into practice for our research

2 Our systemrsquos basic working principles and equipmentrsquos complexity are a little difficult to grasp

but hopefully we were able to understand enough of it

3 Theoretically from relation between the power and current we can know the advantages and

disadvantages of AR Coating

4 We were able to assemble the system and run test on its functions Even though we were able to

do this there is still much more work left to do with this system

52 Recommendations

For the Tensile Testing the following can be said

1 Ask the provider to check on the process of heat treatment on the SUM 23 material and give

them the information we have gathered through our test so they can correct for the mechanical

properties found if any change is needed

2 To avoid the problem of the inaccuracy of the poor adhesion of strain gauges we can attach

multiple strain gauges to the same one specimen so as to correlate data and improve our results

For the AR Coating the following can be said

1 We need to make sure that there are no physical defects on the main body of the chamber so as to

achieve maximum efficiency in the vacuum process If there was then the vacuum will arrive to

certain point and then start to decrease

2 It would be preferable to add some sort of visual aid that will allow the user to check the inside of

the chamber without actually opening it This will help us determine at what times we should

manipulate the current to better evaporate the substrate

94

REFERENCES

[1] A L Window Strain Gauge Technology Elsevier Applied Science London and New York 2nd

Edition 1992

[2] CC Perry and HR Lissner Strain Gauge Primer McGraw-Hill Book Co Inc New York 1955

[3] James W Dally William F Riley McGraw-Hill 1978

[4] University of Colorado Boulder BEC - What is it and where did the idea come from

httpwwwcoloradoeduphysics2000becwhat_is_ithtml

[5] Ultraslow Light amp Bose-Einstein Condensates Two-way Control with Coherent Light amp Atom

Fields Harvard Hau Lab Dr Lene Vestergaard Hau Optics amp Photonics News 16 1995

[6] The Art of Taming Light Ultra-slow and Stopped Light Harvard Hau Lab Dr Lene

Vestergaard Hau Europhysics News 2004

[7] Nonlinear Optics Shocking Superfluids Harvard Hau Lab Dr Lene Vestergaard Hau Nature

Physics 2007

[8] Model P3 Strain Indicator and Recorder Instruction Manual Vishay Micro-Measurements 2005

[9] Granville-Phillips Series 375 Convectron Vacuum Gauge Controller Instruction Manual Brooks

Automation 2008

[10] Effect of Film Thickness on the Validity of the Sauerbrey Equation for Hydrated Polyelectrolyte

Films Vogt Lin Wu White 2004

[11] Quartz Crystal Microbalance Study of DNA Immobilization and Hybridization for DNA Sensor

Development Chang Zhao 2008

[12] Installation of Strain Gages with SR-4 PrecoatAdhesive Vishay Micro-Measurements 2005

[13] Strain Gauge Measurement ndash A Tutorial National Instruments 1998

[14] Correlation between Vickers Hardness Number and Yield Stress of Cold-Formed Products

Yavuz Tekkaya

[15] httpsenwikipediaorg

Page 25: PC Hinge Materials Testing and AR Laser Diode Coating

25

232 AR Coating Basic Principles

Anti-reflective (AR) coating is a type of optical coating applied to the surface of lenses and other

optical devices (in our case we planned to apply it to a laser diode) to reduce reflection This improves

the efficiency of the system since less light is lost The primary benefit is the elimination of the reflection

itself

When light the medium (glass) it will produce reflection if 100 of the light comes from the air and

enters the glass because therersquos a difference between the index of refraction some of the light will go out

and when the light is coming out of the glass into the air once again because of the difference between

index of refraction some of the light wonrsquot be able to pass through the medium

When the light makes the first trip into the glass there was a loss of about 4 in the reflection and

when the light makes the trip back outside there was another loss of about 4 so when we assume that

100 of the light interacts with the medium actually therersquos just about 92 acting (we neglect the light

absorbed by the glass around 05) To illustrate this idea please refer to figure 2-13

Fig 2-13 Simple Model for Light in Glass Medium

When we apply the AR Coating the light that enters will only have a loss of about 05 and when

making the trip back outside again only 05 of light is loss so we get the result of increasing the light

passing through up to 99 (again neglecting the light absorbed by the glass around 05) To illustrate

this idea please refer to figure 2-14

26

Fig 2-14 Simple Model for Light in Glass Medium after AR Coating

The AR Coating can reduce reflection of incoming light In the case that light hits perpendicular to

the surface of the medium the intensity of the reflection can be calculated using the Reflection

Coefficient

Where n0 and ns are the refractive indices of the first and second media respectively The value of R

varies from 0 (no reflection) to 1 (all light reflected) and is usually quoted as a percentage

Complementary to R is the transmission coefficient or Transmittance If absorption and scattering are

neglected then the value of Transmittance is always 1-R then if a beam of light with intensity I is

incident on the surface a beam of intensity RI is reflected and a beam with intensity TI is transmitted to

the medium

The optimal value is called the Optimal Index of Refraction and is described as

For glass with ns around 15 in air (n0 around 10) then the optimum refractive index will be n1 =

1225

To reduce the refraction in this case we now mean the one that is produced inside the chamber of the

Laser diode the easiest way is to apply a low reflectivity AR coating on the surface of the laser To

measure the appropriate thickness of the coating layer we can use the equations described above By

applying a coat exactly

thickness film we can assure that a certain wavelength is transmitted The

27

reflected waves from the back of the glass medium will be half a wavelength out of phase So they

interfere destructively Because all reflected waves are interfered the maximum amount of light passes

through the coating Please refer to figure 2-15 to illustrate this idea

Fig 2-15 Light Passing through AR Coat and Glass

The most common process to attain this final product is by vacuum deposition For the best coating

results we need to lower the pressure inside the vacuum system to torr

Fig 2-16 Lens without (Top) and With (Bottom) AR Coating

28

233 Laser Diode Basic Principles

A laser diode is a laser whose active medium is a semiconductor similar to that found in

light-emitting diodes (LEDs) Please refer to figure 2-17 The most common type of laser diode is formed

from a p-n junction and powered by injected electric current

Fig 2-17 Laser Diode

Laser diodes are formed by doping a very thin layer on the surface of a crystal wafer The crystal is

doped to produce the n-type region and a p-type region one above the other

By referring to figure 1-2 we can see the basic structure of a working laser When the laser diode has

a current passing through it the light will get excited inside its gain medium and then will start to

resonate this process is called pumping The current exceeds the critical current and then it comes out as

laser light Please refer to figure 1-3 Since we use an external cavity laser we need to apply the AR

coating to the diode and adjust a diffraction grating The laser light comes out the diode and bounces on

the grating making the resonance externally and this becomes the ldquocavityrdquo as shown in figure 2-18

Fig 2-18 Tunable Laser Basic Configuration

29

The most important feature of the external cavity laser is that we can adjust the wavelength easily just

by changing the diffraction gratingrsquos angle and in the end this is the output wavelength of the laser For

different wavelengths there will be different levels of visible light as shown in figure 2-19

Fig 2-19 Light Spectrum

234 Quartz Microbalance System

A Quartz Crystal Microbalance is an instrument that measures a mass per unit area by measuring the

change in frequency of a quartz crystal resonator The resonance is disturbed by the addition or removal

of a small mass due to oxide growthdecay or film deposition (which is the case in our study) at the

surface of the acoustic resonator The QCM can be used under vacuum in gas phase and more recently in

liquid environments It is useful for monitoring the rate of deposition in thin film deposition systems

under vacuum Frequency measurements are easily made with high precision

For our research we used the Sigma Instruments SQM-160 RateThickness Monitor shown in figure

2-20

Fig 2-20 Front and Back Panels of SQM-160

30

The microbalance uses Quartz as the resonator Quartz is one member of the family of crystals that

experience the Piezoelectric Effect

Piezoelectricity is the charge that accumulates in certain solid materials in response to applied

mechanical stress It means electricity resulting from pressure It was discovered in 1880 by Jacques and

Pierre Curie It is understood as the linear electromechanical interaction between the mechanical and the

electrical state in crystalline materials with no inversion symmetry It is a reversible process in that

materials exhibiting direct piezoelectricity also exhibit the reverse This means that the internal generation

of electrical resulting from applied mechanical force and vice versa

By using the piezoelectric effect we can probe as an acoustic resonance by electrical means Applying

alternating current to the quartz crystal induces oscillations This creates a shear wave We can use these

qualities to determine the resonance frequency at high accuracy

The frequency of oscillation of the crystal is partially dependent in the thickness of the crystal During

normal operation all the variables are held constant so a change in thickness correlates directly to a

change in frequency As mass is deposited or etched away the thickness increases or decreases and so the

frequency of oscillation changes accordingly With some simplifying assumptions the frequency change

can be quantified and correlated precisely to the mass change using the Sauerbreyrsquos Equation

Developed by G Sauerbrey in 1959 it is a method for correlating changes in the oscillation

frequency of a piezoelectric crystal with the mass deposited on it It is defined as below

Where f0 is the Resonant frequency Δf is the Frequency change Δm is the mass change A is the

piezoelectrically active area of the crystal q is the Density of quartz (2648 gcmsup3) and μq is the Shear

modulus of quarts(2947x gcmssup2)

Because the film is treated as an extension of thickness Sauerbreyrsquos equation only applies to systems

in which the following 3 conditions are met

Deposited mass must be rigid

Deposited mass must be distributed evenly

The frequency change

lt002

If the change is greater than 2 the Z-match method must be used to determine the change in mass

It is defined as

Where fL is the frequency of the loaded crystal fU is the resonant frequency Nq is the frequency

constant (1668x HzAring) Δm is the mass change A is the piezoelectrically active area of the crystal

31

q is the density of quartz Z is the method constant f is the density of film μq Is the shear modulus of

quarts and μf is the shear modulus of film

The Sauerbrey equation cannot be applied to systems under liquid medium

The crystals are seed crystals plated with gold on both top and bottom for applications A crystal is

shown in figure 2-21 The QCM consists of a thin piezoelectric plate with electrodes evaporated on both

sides Due to the piezoelectric effect AC voltage across the electrodes induces a shear deformation and

vice versa The electromechanical coupling provides a simple way to detect an acoustic resonance by

electrical means

The Z also called Z-factor is a constant value for different materials and it is shown together with the

density of different materials in table 2-2 below

Fig 2-21 QCM Crystals

The Oscillator of the SQM-160 is shown in figure 2-22 and the equivalent circuit for the Resonant

Oscillator is shown in figure 2-23

Fig 2-22 SQM-160 Oscillator

32

Fig 2-23 Oscillator Circuit

33

Table 2-2 Z-Ratios for Different Materials

Table 2-2 Continued

34

Table 2-2 Continued

35

Table 2-2 Continued

36

Table 2-2 Continued

37

Table 2-2 Continued

38

Table 2-2 Continued

235 Vacuum Chamber System

Vacuum Evaporation is the process of depositing thin films of materials onto surfaces The technique

consists of pumping a vacuum chamber to pressures of less than torr and heating a material to

produce a flux of vapor in order to deposit the material onto a surface The material to be vaporized is

typically heated until its vapor pressure is high enough to produce a flux several Angstrom per second by

using an electrically resistive heater or bombardment by a high voltage beam The process was invented

by Henri Nestle in 1886 for food industry

In here the system has been pumped to a vacuum of Torr When a high current is passed

through the filament boat the filament boat is heated over the desired metal evaporation temperature and

so evaporation starts When the evaporation process is finished and the metal cools down crystals

condensate in the surface of the wafer From the weight of the evaporated material the distance between

the filament boat and the wafer we are able to calculate the deposition thickness and we can also use the

mass detector follower like the Quartz crystal resonator microbalance system In the process of

evaporation we usually use a board in between the filament boat and the wafer This is because before we

arrive to the desired evaporation temperature there will be some impurities that will be vaporized in the

controlled environment so we first use a small current and the board in between to get rid of those

impurities and this raises the purity of the deposition material

39

A vacuum evaporation system is shown in figure 2-24

Fig 2-24 Vacuum Evaporation System

Rough Vacuum 760 ~ 1 torr

Medium Vacuum 1 ~ torr

High Vacuum ~ torr

Ultra-High Vacuum Lower than torr

Table 2-3 Classification of Vacuum

For our study we need to use a Turbo Pump A regular turbo pump is shown in figure 2-25

Fig 2-25 Turbo Pump

For our research we used the Pfeiffer TCP 015 Electronic Drive Unit and Granville Phillips 375

Convectron shown below in figure 2-26

40

Fig 2-26 Control and Measurement Equipment

The electronic drive controls the turbo pump and the Convectron measures the pressure inside our

chamber The turbo pump is a type of vacuum pump used to maintain high vacuum Most turbo pumps

are centrifugal When we start the pumping we need to use a mechanical pump so as to decrease the

pressure inside the system from constant atmospheric pressure to torr and then the use dispersion

pump to continue the vacuum until we get to the desired pressure We need to notice though when we

start the dispersion pump we canrsquot turn off the mechanical pump and they both need to run together If

we need to turn off the pumping we first turn off the dispersion pump wait for it to completely stop and

then turn off the mechanical pump

Our completely assembled system is shown in figure 2-27 below

Fig 2-27 Complete System

41

Chapter 3 TENSILE TESTING IN DEPTH

31 Experimentrsquos Purpose and Principles

By means of Universal testing machine and Strain gauges we were able to observe discuss and

analyze the phenomena created when a specimen of certain material is manipulated under an external load

and determine the stress strain and deformation values later we can use the graphing methods of

stress-strain diagram to describe it

The main point of this experiment is that after the tensile specimen is tested use computer analysis

and the actual strain data and after statistical adjustment make the final results report (Tensile testing

experiment is in accordance with ASTM E8)

32 Experimentrsquos Equipment

321 Universal Testing Machine

For the materials testing experiment part of this research we use a Universal Testing Machine as

shown in figure 31 The maximum load it can apply is 100 Ton After the test specimen is secured on the

device with the use of instrumentation the load exerted and the effects of this become apparent on the

specimen and even the smallest of changes can be recorded For our research we used the Chun Yen

Testing Machines Co Ltd 100 Ton Micro Computer Universal Tensile Tester

Fig 31 Universal Testing Machine

42

Table 31 shows the specifications for this machine

Max Capacity 100 Ton

Accuracy plusmn1

Tension (mm) Max Space 1150mm

Grip for Rod 20-70mm

Ram Stroke 250mm

Effective Column Interval 940mm

Crosshead Speed 300mmmin

Testing Speed 0-50mmmin

Volume of Machine 1700times1000times3350mm(LtimesWtimesH)

Volume of Control Panel 1000times800times1500mm(LtimesWtimesH)

Weight 8000kg

Power 3∮220V 20A

Computer AMD K6-2-350

OS Windows XP

Screen 15rdquo CRT

Table 3-1 Chun Yen Testing Machine Specs Table

The connections diagram is shown in figure 3-2

Fig 3-2 Diagram for System Connections

43

When the test specimen is placed when the external force is applied the Load Cell can measure the

size of the applied force and the Encoder measures the expansion rate of change The Local Controller

receives all the information from the 2 units after arranging the results they are displayed in the

computer and they can be afterwards submitted for more complex analysis such as Finite Element

Analysis and we can get the Stress-Strain Diagram

322 Strain Measurement Equipment

The equipment used in our research provides a four-channel measurement that means we can use up

to 4 strain gauges at a time to do our measurements and provides 3 different bridge arrangements as

shown in figure 3-3

(a) (b) (c)

Fig 3-3 Input Connections for Strain Indicator

Figure 3-3 (a) is the Quarter Bridge (b) is the Half Bridge and (c) is the Full Bridge and Transducers

For our study we used the Quarter Bridge and use the Strain Gauge values to decide the position of the

connecting wires The Strain indicator is shown in figure 3-4

Fig 3-4 Vishay Micro-Measurements Model P3 Strain Indicator and Recorder

44

Input Connections Tool Free eccentric lever release

4-channel input

Wire diameter16-28AWG

Bridge Configurations Quarter- Half- and Full Bridge

Bridge Impedance 60-2000Ω

Display 128 64 pixel FSTN positive gray LCD

Data Conversion AD Converter filter

Measurement Range Resolution Strain Range plusmn155mVV

Resolution plusmn00005mVV

Measurement Accuracy plusmn01 of reading plusmn3 counts

Gage Factor Control 0500-9900

Balance Control Software either manual or automatic

Bridge Excitation 15VDC nominal

Communication Interface USB Cable Included

Data Storage Removable Media Card

Shunt Calibration Across bridge completion resistors controlled

by software When Gage Factor=200

120Ω350Ω1000Ω

Analog Output Value 0 to 25V max

Ranges plusmn320 microε plusmn3200 microε plusmn32000 microε

Error 05 output voltage +5mV

Max Error 14 output voltage + 20mV

Update rate 480 samplessec

Output Load 2000Ω

Power Battery Two Alkaline D cells

Battery life 400 hours typ

USB 5V 100mA

Operational Environment Temperature 0-50

Humidity Up to 90 Non-condensing

Case Aluminum Alloy

Size and Weight 228times152times152(mm) 20(kg)

Table 3-2 Vishay Micro-Measurements Model P3 Strain Indicator and Recorder Specs

45

323 Strain Gauge

The strain gaugersquos main basic principle is to use a resistancersquos characteristics to measure the strain

The inside connections of the strain indicator are shown in figure 3-5

Fig 3-5 Inner Connections

As shown above this is a quarter-bridge connection We connect equal-length 3 wires to the 2

connections allowed by the strain gauge wire 1 and 3 can be used to cancel out the effects of temperature

to the resistance and because of the addition of wires 1 and 3 wire 2 can directly measure the experiment

results from the strain gauge and therefore the strain developed with no influence of temperature

If there were no two measuring leads then the relations will be

R 4 =R g +2R L

Where Rg is the Strain Gauge Value and RL is the wire resistance then

4

4

R

R=

Lg

g

RR

R

2

=

gL

gg

RR

RR

21

amp

4

4

R

R=

g

g

R

R(1- L)

Where L is the Signal Loss Factor and so

L =gL

gL

RR

RR

21

2

g

L

R

2R if

g

L

R

2Rltlt1

46

(Actual Value R g =120R L =08g

L

R

2Ris always much smaller than 1)

R 4 =R g +2R LR 2 =R 3 =rR gR 1 =R g 32 RR =0

V 0 =V 2)1( r

r

(

4

4

R

R-

1

1

R

R)

The first term describes loss attenuation effects second term describes loss of balancing capabilities

effects

V 0 =V 2)1( r

r

[

)2

(Lg

g

RR

R

+

T

Lg

g

RR

R

)

2( + T

Lg

L

RR

R

)

2

2( -(

g

g

R

R) T ]

The first term describes loss attenuation effects and loss of balancing capabilities effects the second

third and fourth terms describe the temperature effects on the wire

For the three-wire method we have

L =gL

gL

RR

RR

1

g

L

R

R if

g

L

R

Rltlt1

V 0 =V 2)1( r

r

[

)(Lg

g

RR

R

+

T

Lg

g

RR

R

)( + T

Lg

L

RR

R

)

2( -

T

Lg

g

RR

R

)( - T

Lg

L

RR

R

)

2( ]

V 0 = V2)1( r

r

)(

Lg

g

RR

R

In the last four terms inside parenthesis we can see the effects of temperature being cancelled out and the

effect on first term is not great so this is the reason why in our research we use three wires

47

324 Specimen Measurements

The tensile specimens used in this research are compliant of ASTM E8 Tensile parameters as shown

in figure 3-6

Fig 3-6 Tensile Specimen

Diameter

D(mm)

Gauge

Length

G(mm)

Smallest

Arc

Radius

R(mm)

Shortest

Area

A(mm)

Total

Length

L(mm)

Clamping

Area

Length

B(mm)

Clamping

Area

Diameter

C(mm)

Bar 125 02 625 01 gt10 gt75 ~ 145 ~ 35 20

Table 3-3 Specifications for Round Bar

33 Experiment Procedure

1 Attaching the Strain Gauge to the Tensile Specimen

(1) Prepare 1 ASTM E8 compliant tensile specimen round bar as shown in figure 3-7

(2) Prepare Strain Gauge as those described in table 3-4

(3) Prepare other consumables and adhesive agent such as epoxy adhesive or

cyanoacrylate adhesive as shown in figure 3-8

48

Fig 3-7 Actual Tensile Specimen

Fig 3-8 Other Materials Used (Such as Alcohol gauze transparent tape adhesive)

Gage Type

EA-06-120LZ-120E

Resistance in ohms at 24∘C

1200plusmn03

Gage Factor at 24∘C

2075plusmn05

Transverse Sensitivity at 24∘C

(+07plusmn02)

Table 3-4 Specifications for Strain Gauge

2 Attaching Strain Gauge

As shown in following figures we shall explain the attachment of the strain gauge

(1) Use sand paper and a rasp to clean thoroughly the surface where the strain gauge will be

attached to

49

(a)

(2) Use alcohol to wash the surface where the strain gauge will be attached and use gauze to rub

it off

(b)

(3) Find a clean surface and clean it with alcohol and gauze

(c)

(4) Place the strain gauge in the clean surface Use a piece of transparent tape on top of the strain

gauge after securely placed rip it off the surface carefully

50

(d)

(5) Use a piece of white paper to mark the place where the strain gauge will be attached and in

this way we can make sure that the strain gauge will be placed as horizontally and vertically

correct as possible

(e)

(6) In the place where we had our mark place the strain gauge

(f)

(7) Carefully lift one side of the tape and apply some of the adhesive agent to both the strain

gauge and specimenrsquos surface

(g)

51

(8) We need to make sure that the gauge and the specimen will be firmly attached so we gently

apply pressure with our thumb

(h)

(9) After the adhesive is fully dry we can carefully rip off the tape

(i)

(10) We need to do the whole process twice one for the horizontally placed strain gauge and one

for the vertically placed strain gauge

52

(j)

(11) We now proceed to solder the wires to the strain gauge

(k)

(12) After soldering we use a Volt Multimeter to measure that there is no contact between wires

If there is none then the specimen is ready for testing

(l)

(13) We now need to measure a 5cm distance and mark it to check and compare the elongation

before and after the tensile testing

(m)

53

Fig 3-9 Specimen-Strain Gauge Process

3 Tensile Test

(1) Enter the computer application that controls the tensile testing machine

(2) Turn on the tensile testing machine main switch

(3) Adjust the hydraulic pump to go back to its original position

(4) Bring the lowering motor down to a distance enough so as to attach the tensile specimen to the

system open the clamps and secure the specimen

(a)

(5) Connect all the necessary wires to the strain indicator equipment

54

(b)

(6) Start the ascending motor and wait for the expansion

(c)

Fig 3-10 Specimen-Tensile Testing Process

4 Start the Test

(1) Enter the software application and enter some variables needed for the experiment in the

specific screen

(2) Go back to the main screen and press the [測試] (measure) button to start the test and auto

recording in the software

(3) After the specimen breaks the mechanical device will automatically stop and ask the user to

enter the total displacement We take out the specimen from the testing machine and adjust the

machinersquos position back to its original position

(4) Save the results information

(5) Record the results from the strain indicator

34 Results

From this experiment we can get the Poissonrsquos Ratio Youngrsquos Modulus and Yield Strength etc and

because of the slippage phenomenon in the clamp at the moment of the test then the Elastic Limit will

display some yield phenomena So omit any undesirable results we just take the Yield portion of the

results as reference

In the process of the experiment the most important part to attend to is the attaching of the strain

gauge because the gaugersquos purpose is to measure the strain developed during the test and this strain

might be very small If the gaugersquos angle change during the test ie is not well attached this will affect

the accuracy of the measurements of Poissonrsquos ratio and Youngrsquos modulus

55

The materials provided by the manufacturer are SUM 23 and SUM 43 steel round bars and these two

types of materials have been through different heat treatment processes so they can be sub-divided

further into untreated material heat-treated material and black surface heat treated material for the two

materials with heat treatment the treatment process and finished are different In the end we only have

the mechanical properties that were calculated after our research of these materials

All of the specifications are identical to those shown in figure 3-6

341 SUM 23

Fig 3-11 SUM 23 Untreated Material

Number 7 10

Hardness(HRB) 74 75

Yield Stress (MPa) 448 440

Tensile Strength (MPa) 544 560

Poissonrsquos Ratio 029 027

Youngrsquos Modulus (GPa) 203 210

Cut-off Area Shrinking () 42 41

Elongation () 1125 1011

Table 3-5 Mechanical Properties of SUM 23 Untreated

56

Stress-Strain Diagram

(a)

(b)

57

Fig 3-12 Stress-Strain Diagrams for (a) 7 Round Bar and (b) 10 Round Bar

Cut-Off Area

(a)

(b)

Fig 3-13 Cut-Off Area of (a) 7 Round Bar and (b) 10 Round Bar

58

SUM 23 Nickel Round Bar

Fig 3-14 SUM 23 Nickel Material

Number 1 2 3 4

Hardness(HRB) 48 50 49 48

Yield Stress (MPa) 370 370 380 400

Tensile Strength (MPa) 455 451 450 450

Poissonrsquos Ratio 028 046 029 026

Youngrsquos Modulus (GPa) 243 303 246 206

Cut-off Area Shrinking () 803 803 726 601

Elongation () 566 65 602 647

Table 3-6 Mechanical Properties of SUM 23 Nickel

59

Stress-Strain Diagram

(a)

60

(b)

(c)

(d)

61

Fig 3-15 Stress-Strain Diagrams for (a) 1 Round Bar (b) 2 Round Bar (c) 3 Round Bar and (d)

4 Round Bar

Cut-Off Area

(a)

(b)

62

(c)

(d)

Fig 3-16 Cut-Off Area of (a) 1 Round Bar (b) 2 Round Bar (c) 3 Round Bar and (d) 4 Round

Bar

63

SUM 23 Black Surface Round Bar

Fig 3-17 SUM 23 Black Surface Material

Number 1 2 3

Hardness(HRB) 51 50 51

Yield Stress (MPa) 378 371 369

Tensile Strength (MPa) 467 465 464

Poissonrsquos Ratio 03 016 04

Youngrsquos Modulus (GPa) 215 266 266

Cut-off Area Shrinking () 986 94 848

Elongation () 748 805 761

Table 3-7 Mechanical Properties of SUM 23 Black Surface Material

64

Stress-Strain Diagram

(a)

(b)

65

(c)

Fig 3-18 Stress-Strain Diagrams for (a) 1 Round Bar 2 Round Bar and (c) 3 Round Bar

Cut-Off Surface

(a)

66

(b)

(c)

Fig 3-19 Cut-Off Surface of (a) 1 Round Bar 2 Round Bar and (c) 3 Round Bar

67

342 SUM 43

Fig 3-20 Untreated SUM 43 Untreated Material

Number 1 5

Hardness(HRB) 76 75

Yield Stress (MPa) 572 594

Tensile Strength (MPa) 743 785

Poissonrsquos Ratio 027 029

Youngrsquos Modulus (GPa) 200 202

Cut-off Area Shrinking () 338 2944

Elongation () 857 894

Table 3-8 Mechanical Properties of SUM 43 Untreated

68

Stress-Strain Diagrams

(a)

(b)

Fig 3-21 Stress-Strain Diagrams for SUM 43 (a) 1 Round Bar and (b) 5 Round Bar

69

Cut-Off Area

(a)

(b)

Fig 3-22 Cut-Off Area of SUM 43 (a) 1 Round Bar and (b) 5 Round Bar

70

SUM 43 Nickel Round Bar

Fig 3-23 SUM 43 Nickel Material

Number 4 5

Hardness(HRB) 51 50

Yield Stress (MPa) 1580 1544

Tensile Strength (MPa) 1639 1625

Poissonrsquos Ratio 03 028

Youngrsquos Modulus (GPa) 194 201

Cut-off Area Shrinking () 1697 137

Elongation () 376 265

Table 3-9 Mechanical Properties of SUM 43 Nickel

71

Stress-Strain Diagrams

(a)

(b)

Fig 3-24 Stress-Strain Diagrams for (a) 4 Round Bar and (b) 5 Round Bar

72

Cut-Off Area

(a)

(b)

Fig 3-25 Cut-Off Area of (a) 4 Round Bar and (b) 5 Round Bar

73

SUM 43 Black Surface Material

Fig 3-26 SUM 43 Black Surface Material

Number 3 5

Hardness(HRB) 56 56

Yield Stress (MPa) 1416 1361

Tensile Strength (MPa) 1591 1402

Poissonrsquos Ratio 029 031

Youngrsquos Modulus (GPa) 200 202

Cut-off Area Shrinking () 139 124

Elongation () 24 24

Table 3-10 Mechanical Properties of SUM 43 Black Surface Material

74

Stress-Strain Diagrams

0 2 4 6 8 10 12 14

-200

0

200

400

600

800

1000

1200

1400

1600

1800

應力 (MPa)

應變()

(a)

0 2 4 6 8 10

-200

0

200

400

600

800

1000

1200

1400

1600

應力

(MPa)

位移 ()

(b)

Fig 3-27 Stress-Strain Diagrams for (a) 3 Round Bar and (b) 5 Round Bar

(Note These curves were formulated using Visual Solutions Inc VisSim Software)

75

Cut-Off Area

(a)

(b)

Fig 3-28 Cut-Off Area of (a) 3 Round Bar and (b) 5 Round Bar

76

The force value (N) was retrieved from the Universal Testing Machine

The Poissonrsquos Ratio (ε) is calculated as

ε =

the values for the Poissonrsquos Ratio are in average around 0297

The Youngrsquos Modulus (E) is calculated as

E =

Where

Stress =

Cross-sectional Area =

where D is the Diameter

The value for D was in average around 1258 mm

The values shown by the computer because there is Slippage phenomena between the Clamp and the

specimen will not be taken into consideration for the elongation strain and Youngrsquos modulus and we will

refer to the values that we have meticulously calculated

77

Chapter 4 AR COATING IN DEPTH

41 Experimentrsquos Purpose and Principles

By means of a vacuum chamber and several other instruments we intend to apply Anti-Reflective

Coating using deposition process to a laser diode and in this way reduce its refraction so as to make it

lose less light in the process of amplification and we can control certain wavelengths we want produced

for certain desired applications in our case we are attempting to re-create a Bose-Einstein Condensate

An optimal BEC apparatus is shown in figure 4-1

Fig 4-1 BEC Apparatus

The main point of this experiment is to build a vacuum chamber system attach all the instrumentation

needed (Vacuum pump deposition meter and voltmeter) and use it to apply AR coating to a laser diode

After we have accomplished the AR coating other team will be in charge of designing the BEC apparatus

and use the results of our research

78

42 Experimentrsquos Equipment

421 Vacuum Chamber

For this research we designed a vacuum chamber whose main body is shown in figure 4-2 Its

dimensions are

Width 240 mm

Length 240 mm

Height 200 mm

Outer Diameter 4 in

Inner Diameter 15 in

Fig 4-2 Vacuum Chamber Main Body

The chamber is made up of 6 pass ways pass way A is the connection with the Laser Deposition

Equipment pass way B is the connection with the Turbo Pump and pass way C is for the connection with

the Deposition Source

A

C

B

79

Pass way C is for the deposition source as mentioned above This is a system where a thermal

resistance is heated by passing a high current through it which heats up a filament boat (made of tungsten)

where the material to be evaporated is place We control the temperature as such that the material will

evaporate and the heat will not cause the filament boat to crack

Because P = Isup2 R (where P is power I is current and R is resistance) to avoid the current to flow

where it is not desired we decided that the material for the Thermocouple shown in figure 4-3 should be

Copper ᴓ 63 mm We choose it that way because Copper has very good heat dissipation characteristics

and the resistance value is low It can reduce the value of the current enough to make the thermocouple to

create heat

Fig 4-3 Thermocouple

To the thermocouple we attach the tungsten filament boat We need to take notice of materials to be

used in this design because when using high current the tungsten filament boar will heat up and so the

material must be able to keep up with the heating potential of tungsten and has a low coefficient of heat

dissipation to avoid the tungsten to fail when heating up and therefore not evaporating Considering all

this we decide to use Stainless Steel

Because this clamp will be assembled inside the chamber after many revisions it was determined it

will have the shape shown in figure 4-4

Fig 4-4 Filament Boat Clamp Design

80

For the tungsten filament boat we bought the product from a distributor The dimensions are

Length 100 mm

Width 10 mm

Height 1 mm

Our thermocouple is 15 in but the pass way C is 4 in so we need to attach a Flange that connects

15in to 4in Because these specifications are quite difficult to achieve by Milling we had to use

electrical wire cutting

For the laser clamping system where the laser that is going to be AR coated will be placed will be

connected to pass way A the assembly is shown in figure 4-5 below

Fig 4-5 Cover Assembly

For this design we used an O-ring instead of a gasket so as to save time The design of the assembly

where the laser will be placed is shown in figure 4-6

Fig 4-6 Upper Cover Inner Assembly

D

E

F

81

Point D is the plate in the assembly where the laser diode will be fixed Because of the easy

processing we decide to use Aluminum and it is screwed to the top cover Point E is the connection for

the Quartz crystal resonator and it is designed in the same as point F in this way the results of the quartz

microbalance system will be more accurate in real time Point F is the final resting place for the laser

diode We use a Thor Labs Base with dimensions of ᴓ 9mm and ᴓ 56mm for two different size laser

diodes It just needs to be plugged in for easy installation

From figure 4-6 we know that the system needs signal system connections and because of the

change in temperature inside the chamber this could affect the functioning of the quartz microbalance so

we also need to install water tubes for cooling This is shown in figure 4-7 below

Fig 4-7 Diagram of Upper Cover Connections

In figure 4-8 we show the Feed through connections and their functions

Fig 4-8 Feed through Diagram

82

1 SQM-160 wire 5 Laser Connection 1 (Vin)

2 SQM-160 (G) 6 Laser Connection 2 (G)

3 K-Type-1 7 Laser Connection 3 (PD)

4 K-Type-2 8 Not In Use

The fully assembled chamber is shown in figure 4-9

Fig 4-9 Fully Assembled Chamber

422 Quartz Crystal Microbalance

For measuring the deposition on our target for coating we used the Inficon SQM-160 RateThickness

Monitor It is an easy to use instrument for measuring many types of thin-film coatings as shown in

figure 4-10

(a) Front Panel (b) Back Panel

Fig 4-10 Inficon SQM-160

83

Table 4-1 shows the technical specifications for this equipment

Number of sensors 2 Standard 4 additional optional

Sensor Frequency Range 40 MHz ~ 60 MHz

Reference Frequency Accuracy 002

Thickness Display Resolution 1 Aring

Thickness Resolution 015 Aring (Std) 0037 Aring (Hi Res)

Density of Stored Films 05-9999 gmcc

Tooling 10-399

Z-Factor 010-1000

Final Thickness 0000-9999k Aring

Measurement Period 15 to 2 sec

Simulation Mode Yes

Frequency Mode Yes

Rate Resolution 011 Arings

Dual Crystal Yes

Etch Mode Yes

Crystal Tooling 10-399

Crystal Fail Min Max 40 to 60 MHz 41 to 61 MHz

Power 100-120 200-240~plusmn10 nominal 20W

Operation Environment 0degC ~ 50degC

0 ~ 80 RH non-condensing

0 ~ 2000 meters

Class 1 Equipment

Pollution Degree 2

Rack Dimensions 885mm x 2127mm x 1969mm

Weight 27 kg

Table 4-1 Inficon SQM-160 RateThickness Monitor Specs

84

To the SQM-160 we need to connect an Oscillator We use the Sigma Instruments Remote Oscillator

Ser No 2 268 as shown in figure 4-11

Fig 4-11 Sigma Instruments Remote Oscillator

The connections diagram is shown in figure 4-12

Fig 4-12 SQM-160 Connections Diagram

85

423 Turbo Pump

For our experiments we used the Pfeiffer TCP 015 Electronic Drive Unit shown below in figure 4-13

Table 4-2 shows the technical specifications for this equipment

(a) Front Panel (b) Back Panel

Fig 4-13 Pfeiffer TCP 015 Electronic Drive

Connection Voltage (100V) 90-112

Mains Frequency 5060 Hz

Start-up Current 22 A

Nominal Frequency 1500 Hz

Rotation Speed 10V = 1500Hz plusmn2

Analog Output Current 10 V = 25 A plusmn 5

Rotation Speed Switchpoint 750 Hz

Works Setting 8 min

Permissible Ambient Temperature 0degC ~ 40degC

Dimensions Front Panel 1285mm x 1063mm

Insertion Length 227mm

Weight 27 Kg

Table 4-2 Pfeiffer TCP 015 Electronic Drive Specs

86

The connections diagram is shown in figure 4-14

Fig 4-14Connections Diagram for Pfeiffer TCP 015

To measure the pressure inside the chamber we use the Granville Phillips 375 Convectron Vacuum

Pressure Controller shown in figure 4-15

(a) Front Panel (b) Back Panel

Fig 4-15 Granville Phillips 375 Convectron

87

Its dimensions are shown in figure 4-16

Fig 4-16 Dimensions of Convectron

Table 4-3 shows the technical specifications for this equipment

Table 4-3 Granville Phillips 375 Convectron Vacuum Pressure Controller Specs

88

424 Multimeter

For our experiment we used the Keithley 2000 Digital Multimeter as shown in figure 4-17

(a) Front Panel (b) Back Panel

Fig 4-17 Keithley Model 2000 6-12-Digit Digital Multimeter

Its technical specifications are shown in table 4-4

Table 4-4 Keithley Model 2000 6-12-Digit Digital Multimeter Specs

89

43 Experiment Procedure

1 Connecting together the equipment and the chamber

(1) We first connect the resonator to the thickness monitor and connect the other side to the

chamber

(2) We now connect the flexible tubes to the turbo pump on one side and to the chamber on the

other

(3) We need to check that tubes are tightly connected to avoid any leaks in the vacuum pumping

process which will not allow us to get to our goal of Torr As shown in figure 4-18

(4) Connect the convectron to the system as shown in figure 4-19

Fig 4-18 checking for leaks using alcohol

Fig 4-19 Convectron attached to System

90

(5) Attach the clamps of the Multimeter to the bottom of the chamber as shown in figure 4-20

(6) Place the Quartz crystal in place

(7) Close tight vacuum chamber

(8) Connect all electrical appliances to power source

Fig 4-20 Multimeter Connections

2 Starting up the System

(1) We turn on all the devices as such Check all systems are ready to function Reset all values

that might be left over from previous tests

(2) Start the thickness monitor and set all values for this experiment In our case we got to testing

the system but not actual coating So we used the simulation mode of the thickness monitor as

shown in figure 4-21

Fig 4-21 Simulation Mode

91

(3) Start the turbo pump Make sure the lid on the vacuum chamber is tightly closed

(4) Start convectron and record initial pressure

(5) Start Multimeter and record initial current

3 Coating Process

(1) If we have the deposition material inside the filament boat the power source for the high

current must be started as well

(2) Record all initial values for thickness current pressure

(3) For an ideal experiment we need a thickness of around 101 nm a pressure of Torr and

a current of 300 A

44 Results

From previous experiments we have shown that we can turn a LED into a laser by means of AR

Coating In figure 4-22 shown below we can compare the actual results of a Diode before and after AR

coating From the blue line we can see that when the diode is at a current of 15mA its light will change

from LED to laser and if we look at the red line its critical current is around 30 to 35 mA

Fig 4-22 AR Coating Comparison for Laser Diodes

This means that the light emitted is not as strong as if the diode had been coated because inside the

chamber there must be some excitation first so the reflectivity of both sides inside the diode must be high

So because of the coating in one of the sides we have opened a door and let the light come out so the

critical current is risen as such and will be higher value than that of before the coating

92

In the following figures we can see the difference between before and after coating in a material The

thickness is around 1016 nm for this material

Fig 4-23 Before Coating

Fig 4-24 After Coating

93

Chapter 5 CONCLUSIONS AND RECOMMENDATIONS

51 Conclusions

For the first part of this independent study taking into consideration the data that came out of our

research and that sent by the provider we can say

1 SUM 23 after heat treatment will unexpectedly develop cracking in the middle of the tensile

testing process and suddenly break

2 Itrsquos possible that in the process of heat treatment to the SUM 23 material the treatment was not

uniform and this will create a pre-loaded moment force on one side that pushes on the other side

of the specimen resulting in material deformation

3 In the process of attaching the strain gauges to the materials it is very easy to make errors due to

poor adhesion or sudden removal in the tensile testing process

For our second part of the independent study the following can be made

1 At the beginning of this independent study we had no idea what Bose-Einstein Condensate was

or what was its purpose After much literature we finally comprehended the basic principles to

put into practice for our research

2 Our systemrsquos basic working principles and equipmentrsquos complexity are a little difficult to grasp

but hopefully we were able to understand enough of it

3 Theoretically from relation between the power and current we can know the advantages and

disadvantages of AR Coating

4 We were able to assemble the system and run test on its functions Even though we were able to

do this there is still much more work left to do with this system

52 Recommendations

For the Tensile Testing the following can be said

1 Ask the provider to check on the process of heat treatment on the SUM 23 material and give

them the information we have gathered through our test so they can correct for the mechanical

properties found if any change is needed

2 To avoid the problem of the inaccuracy of the poor adhesion of strain gauges we can attach

multiple strain gauges to the same one specimen so as to correlate data and improve our results

For the AR Coating the following can be said

1 We need to make sure that there are no physical defects on the main body of the chamber so as to

achieve maximum efficiency in the vacuum process If there was then the vacuum will arrive to

certain point and then start to decrease

2 It would be preferable to add some sort of visual aid that will allow the user to check the inside of

the chamber without actually opening it This will help us determine at what times we should

manipulate the current to better evaporate the substrate

94

REFERENCES

[1] A L Window Strain Gauge Technology Elsevier Applied Science London and New York 2nd

Edition 1992

[2] CC Perry and HR Lissner Strain Gauge Primer McGraw-Hill Book Co Inc New York 1955

[3] James W Dally William F Riley McGraw-Hill 1978

[4] University of Colorado Boulder BEC - What is it and where did the idea come from

httpwwwcoloradoeduphysics2000becwhat_is_ithtml

[5] Ultraslow Light amp Bose-Einstein Condensates Two-way Control with Coherent Light amp Atom

Fields Harvard Hau Lab Dr Lene Vestergaard Hau Optics amp Photonics News 16 1995

[6] The Art of Taming Light Ultra-slow and Stopped Light Harvard Hau Lab Dr Lene

Vestergaard Hau Europhysics News 2004

[7] Nonlinear Optics Shocking Superfluids Harvard Hau Lab Dr Lene Vestergaard Hau Nature

Physics 2007

[8] Model P3 Strain Indicator and Recorder Instruction Manual Vishay Micro-Measurements 2005

[9] Granville-Phillips Series 375 Convectron Vacuum Gauge Controller Instruction Manual Brooks

Automation 2008

[10] Effect of Film Thickness on the Validity of the Sauerbrey Equation for Hydrated Polyelectrolyte

Films Vogt Lin Wu White 2004

[11] Quartz Crystal Microbalance Study of DNA Immobilization and Hybridization for DNA Sensor

Development Chang Zhao 2008

[12] Installation of Strain Gages with SR-4 PrecoatAdhesive Vishay Micro-Measurements 2005

[13] Strain Gauge Measurement ndash A Tutorial National Instruments 1998

[14] Correlation between Vickers Hardness Number and Yield Stress of Cold-Formed Products

Yavuz Tekkaya

[15] httpsenwikipediaorg

Page 26: PC Hinge Materials Testing and AR Laser Diode Coating

26

Fig 2-14 Simple Model for Light in Glass Medium after AR Coating

The AR Coating can reduce reflection of incoming light In the case that light hits perpendicular to

the surface of the medium the intensity of the reflection can be calculated using the Reflection

Coefficient

Where n0 and ns are the refractive indices of the first and second media respectively The value of R

varies from 0 (no reflection) to 1 (all light reflected) and is usually quoted as a percentage

Complementary to R is the transmission coefficient or Transmittance If absorption and scattering are

neglected then the value of Transmittance is always 1-R then if a beam of light with intensity I is

incident on the surface a beam of intensity RI is reflected and a beam with intensity TI is transmitted to

the medium

The optimal value is called the Optimal Index of Refraction and is described as

For glass with ns around 15 in air (n0 around 10) then the optimum refractive index will be n1 =

1225

To reduce the refraction in this case we now mean the one that is produced inside the chamber of the

Laser diode the easiest way is to apply a low reflectivity AR coating on the surface of the laser To

measure the appropriate thickness of the coating layer we can use the equations described above By

applying a coat exactly

thickness film we can assure that a certain wavelength is transmitted The

27

reflected waves from the back of the glass medium will be half a wavelength out of phase So they

interfere destructively Because all reflected waves are interfered the maximum amount of light passes

through the coating Please refer to figure 2-15 to illustrate this idea

Fig 2-15 Light Passing through AR Coat and Glass

The most common process to attain this final product is by vacuum deposition For the best coating

results we need to lower the pressure inside the vacuum system to torr

Fig 2-16 Lens without (Top) and With (Bottom) AR Coating

28

233 Laser Diode Basic Principles

A laser diode is a laser whose active medium is a semiconductor similar to that found in

light-emitting diodes (LEDs) Please refer to figure 2-17 The most common type of laser diode is formed

from a p-n junction and powered by injected electric current

Fig 2-17 Laser Diode

Laser diodes are formed by doping a very thin layer on the surface of a crystal wafer The crystal is

doped to produce the n-type region and a p-type region one above the other

By referring to figure 1-2 we can see the basic structure of a working laser When the laser diode has

a current passing through it the light will get excited inside its gain medium and then will start to

resonate this process is called pumping The current exceeds the critical current and then it comes out as

laser light Please refer to figure 1-3 Since we use an external cavity laser we need to apply the AR

coating to the diode and adjust a diffraction grating The laser light comes out the diode and bounces on

the grating making the resonance externally and this becomes the ldquocavityrdquo as shown in figure 2-18

Fig 2-18 Tunable Laser Basic Configuration

29

The most important feature of the external cavity laser is that we can adjust the wavelength easily just

by changing the diffraction gratingrsquos angle and in the end this is the output wavelength of the laser For

different wavelengths there will be different levels of visible light as shown in figure 2-19

Fig 2-19 Light Spectrum

234 Quartz Microbalance System

A Quartz Crystal Microbalance is an instrument that measures a mass per unit area by measuring the

change in frequency of a quartz crystal resonator The resonance is disturbed by the addition or removal

of a small mass due to oxide growthdecay or film deposition (which is the case in our study) at the

surface of the acoustic resonator The QCM can be used under vacuum in gas phase and more recently in

liquid environments It is useful for monitoring the rate of deposition in thin film deposition systems

under vacuum Frequency measurements are easily made with high precision

For our research we used the Sigma Instruments SQM-160 RateThickness Monitor shown in figure

2-20

Fig 2-20 Front and Back Panels of SQM-160

30

The microbalance uses Quartz as the resonator Quartz is one member of the family of crystals that

experience the Piezoelectric Effect

Piezoelectricity is the charge that accumulates in certain solid materials in response to applied

mechanical stress It means electricity resulting from pressure It was discovered in 1880 by Jacques and

Pierre Curie It is understood as the linear electromechanical interaction between the mechanical and the

electrical state in crystalline materials with no inversion symmetry It is a reversible process in that

materials exhibiting direct piezoelectricity also exhibit the reverse This means that the internal generation

of electrical resulting from applied mechanical force and vice versa

By using the piezoelectric effect we can probe as an acoustic resonance by electrical means Applying

alternating current to the quartz crystal induces oscillations This creates a shear wave We can use these

qualities to determine the resonance frequency at high accuracy

The frequency of oscillation of the crystal is partially dependent in the thickness of the crystal During

normal operation all the variables are held constant so a change in thickness correlates directly to a

change in frequency As mass is deposited or etched away the thickness increases or decreases and so the

frequency of oscillation changes accordingly With some simplifying assumptions the frequency change

can be quantified and correlated precisely to the mass change using the Sauerbreyrsquos Equation

Developed by G Sauerbrey in 1959 it is a method for correlating changes in the oscillation

frequency of a piezoelectric crystal with the mass deposited on it It is defined as below

Where f0 is the Resonant frequency Δf is the Frequency change Δm is the mass change A is the

piezoelectrically active area of the crystal q is the Density of quartz (2648 gcmsup3) and μq is the Shear

modulus of quarts(2947x gcmssup2)

Because the film is treated as an extension of thickness Sauerbreyrsquos equation only applies to systems

in which the following 3 conditions are met

Deposited mass must be rigid

Deposited mass must be distributed evenly

The frequency change

lt002

If the change is greater than 2 the Z-match method must be used to determine the change in mass

It is defined as

Where fL is the frequency of the loaded crystal fU is the resonant frequency Nq is the frequency

constant (1668x HzAring) Δm is the mass change A is the piezoelectrically active area of the crystal

31

q is the density of quartz Z is the method constant f is the density of film μq Is the shear modulus of

quarts and μf is the shear modulus of film

The Sauerbrey equation cannot be applied to systems under liquid medium

The crystals are seed crystals plated with gold on both top and bottom for applications A crystal is

shown in figure 2-21 The QCM consists of a thin piezoelectric plate with electrodes evaporated on both

sides Due to the piezoelectric effect AC voltage across the electrodes induces a shear deformation and

vice versa The electromechanical coupling provides a simple way to detect an acoustic resonance by

electrical means

The Z also called Z-factor is a constant value for different materials and it is shown together with the

density of different materials in table 2-2 below

Fig 2-21 QCM Crystals

The Oscillator of the SQM-160 is shown in figure 2-22 and the equivalent circuit for the Resonant

Oscillator is shown in figure 2-23

Fig 2-22 SQM-160 Oscillator

32

Fig 2-23 Oscillator Circuit

33

Table 2-2 Z-Ratios for Different Materials

Table 2-2 Continued

34

Table 2-2 Continued

35

Table 2-2 Continued

36

Table 2-2 Continued

37

Table 2-2 Continued

38

Table 2-2 Continued

235 Vacuum Chamber System

Vacuum Evaporation is the process of depositing thin films of materials onto surfaces The technique

consists of pumping a vacuum chamber to pressures of less than torr and heating a material to

produce a flux of vapor in order to deposit the material onto a surface The material to be vaporized is

typically heated until its vapor pressure is high enough to produce a flux several Angstrom per second by

using an electrically resistive heater or bombardment by a high voltage beam The process was invented

by Henri Nestle in 1886 for food industry

In here the system has been pumped to a vacuum of Torr When a high current is passed

through the filament boat the filament boat is heated over the desired metal evaporation temperature and

so evaporation starts When the evaporation process is finished and the metal cools down crystals

condensate in the surface of the wafer From the weight of the evaporated material the distance between

the filament boat and the wafer we are able to calculate the deposition thickness and we can also use the

mass detector follower like the Quartz crystal resonator microbalance system In the process of

evaporation we usually use a board in between the filament boat and the wafer This is because before we

arrive to the desired evaporation temperature there will be some impurities that will be vaporized in the

controlled environment so we first use a small current and the board in between to get rid of those

impurities and this raises the purity of the deposition material

39

A vacuum evaporation system is shown in figure 2-24

Fig 2-24 Vacuum Evaporation System

Rough Vacuum 760 ~ 1 torr

Medium Vacuum 1 ~ torr

High Vacuum ~ torr

Ultra-High Vacuum Lower than torr

Table 2-3 Classification of Vacuum

For our study we need to use a Turbo Pump A regular turbo pump is shown in figure 2-25

Fig 2-25 Turbo Pump

For our research we used the Pfeiffer TCP 015 Electronic Drive Unit and Granville Phillips 375

Convectron shown below in figure 2-26

40

Fig 2-26 Control and Measurement Equipment

The electronic drive controls the turbo pump and the Convectron measures the pressure inside our

chamber The turbo pump is a type of vacuum pump used to maintain high vacuum Most turbo pumps

are centrifugal When we start the pumping we need to use a mechanical pump so as to decrease the

pressure inside the system from constant atmospheric pressure to torr and then the use dispersion

pump to continue the vacuum until we get to the desired pressure We need to notice though when we

start the dispersion pump we canrsquot turn off the mechanical pump and they both need to run together If

we need to turn off the pumping we first turn off the dispersion pump wait for it to completely stop and

then turn off the mechanical pump

Our completely assembled system is shown in figure 2-27 below

Fig 2-27 Complete System

41

Chapter 3 TENSILE TESTING IN DEPTH

31 Experimentrsquos Purpose and Principles

By means of Universal testing machine and Strain gauges we were able to observe discuss and

analyze the phenomena created when a specimen of certain material is manipulated under an external load

and determine the stress strain and deformation values later we can use the graphing methods of

stress-strain diagram to describe it

The main point of this experiment is that after the tensile specimen is tested use computer analysis

and the actual strain data and after statistical adjustment make the final results report (Tensile testing

experiment is in accordance with ASTM E8)

32 Experimentrsquos Equipment

321 Universal Testing Machine

For the materials testing experiment part of this research we use a Universal Testing Machine as

shown in figure 31 The maximum load it can apply is 100 Ton After the test specimen is secured on the

device with the use of instrumentation the load exerted and the effects of this become apparent on the

specimen and even the smallest of changes can be recorded For our research we used the Chun Yen

Testing Machines Co Ltd 100 Ton Micro Computer Universal Tensile Tester

Fig 31 Universal Testing Machine

42

Table 31 shows the specifications for this machine

Max Capacity 100 Ton

Accuracy plusmn1

Tension (mm) Max Space 1150mm

Grip for Rod 20-70mm

Ram Stroke 250mm

Effective Column Interval 940mm

Crosshead Speed 300mmmin

Testing Speed 0-50mmmin

Volume of Machine 1700times1000times3350mm(LtimesWtimesH)

Volume of Control Panel 1000times800times1500mm(LtimesWtimesH)

Weight 8000kg

Power 3∮220V 20A

Computer AMD K6-2-350

OS Windows XP

Screen 15rdquo CRT

Table 3-1 Chun Yen Testing Machine Specs Table

The connections diagram is shown in figure 3-2

Fig 3-2 Diagram for System Connections

43

When the test specimen is placed when the external force is applied the Load Cell can measure the

size of the applied force and the Encoder measures the expansion rate of change The Local Controller

receives all the information from the 2 units after arranging the results they are displayed in the

computer and they can be afterwards submitted for more complex analysis such as Finite Element

Analysis and we can get the Stress-Strain Diagram

322 Strain Measurement Equipment

The equipment used in our research provides a four-channel measurement that means we can use up

to 4 strain gauges at a time to do our measurements and provides 3 different bridge arrangements as

shown in figure 3-3

(a) (b) (c)

Fig 3-3 Input Connections for Strain Indicator

Figure 3-3 (a) is the Quarter Bridge (b) is the Half Bridge and (c) is the Full Bridge and Transducers

For our study we used the Quarter Bridge and use the Strain Gauge values to decide the position of the

connecting wires The Strain indicator is shown in figure 3-4

Fig 3-4 Vishay Micro-Measurements Model P3 Strain Indicator and Recorder

44

Input Connections Tool Free eccentric lever release

4-channel input

Wire diameter16-28AWG

Bridge Configurations Quarter- Half- and Full Bridge

Bridge Impedance 60-2000Ω

Display 128 64 pixel FSTN positive gray LCD

Data Conversion AD Converter filter

Measurement Range Resolution Strain Range plusmn155mVV

Resolution plusmn00005mVV

Measurement Accuracy plusmn01 of reading plusmn3 counts

Gage Factor Control 0500-9900

Balance Control Software either manual or automatic

Bridge Excitation 15VDC nominal

Communication Interface USB Cable Included

Data Storage Removable Media Card

Shunt Calibration Across bridge completion resistors controlled

by software When Gage Factor=200

120Ω350Ω1000Ω

Analog Output Value 0 to 25V max

Ranges plusmn320 microε plusmn3200 microε plusmn32000 microε

Error 05 output voltage +5mV

Max Error 14 output voltage + 20mV

Update rate 480 samplessec

Output Load 2000Ω

Power Battery Two Alkaline D cells

Battery life 400 hours typ

USB 5V 100mA

Operational Environment Temperature 0-50

Humidity Up to 90 Non-condensing

Case Aluminum Alloy

Size and Weight 228times152times152(mm) 20(kg)

Table 3-2 Vishay Micro-Measurements Model P3 Strain Indicator and Recorder Specs

45

323 Strain Gauge

The strain gaugersquos main basic principle is to use a resistancersquos characteristics to measure the strain

The inside connections of the strain indicator are shown in figure 3-5

Fig 3-5 Inner Connections

As shown above this is a quarter-bridge connection We connect equal-length 3 wires to the 2

connections allowed by the strain gauge wire 1 and 3 can be used to cancel out the effects of temperature

to the resistance and because of the addition of wires 1 and 3 wire 2 can directly measure the experiment

results from the strain gauge and therefore the strain developed with no influence of temperature

If there were no two measuring leads then the relations will be

R 4 =R g +2R L

Where Rg is the Strain Gauge Value and RL is the wire resistance then

4

4

R

R=

Lg

g

RR

R

2

=

gL

gg

RR

RR

21

amp

4

4

R

R=

g

g

R

R(1- L)

Where L is the Signal Loss Factor and so

L =gL

gL

RR

RR

21

2

g

L

R

2R if

g

L

R

2Rltlt1

46

(Actual Value R g =120R L =08g

L

R

2Ris always much smaller than 1)

R 4 =R g +2R LR 2 =R 3 =rR gR 1 =R g 32 RR =0

V 0 =V 2)1( r

r

(

4

4

R

R-

1

1

R

R)

The first term describes loss attenuation effects second term describes loss of balancing capabilities

effects

V 0 =V 2)1( r

r

[

)2

(Lg

g

RR

R

+

T

Lg

g

RR

R

)

2( + T

Lg

L

RR

R

)

2

2( -(

g

g

R

R) T ]

The first term describes loss attenuation effects and loss of balancing capabilities effects the second

third and fourth terms describe the temperature effects on the wire

For the three-wire method we have

L =gL

gL

RR

RR

1

g

L

R

R if

g

L

R

Rltlt1

V 0 =V 2)1( r

r

[

)(Lg

g

RR

R

+

T

Lg

g

RR

R

)( + T

Lg

L

RR

R

)

2( -

T

Lg

g

RR

R

)( - T

Lg

L

RR

R

)

2( ]

V 0 = V2)1( r

r

)(

Lg

g

RR

R

In the last four terms inside parenthesis we can see the effects of temperature being cancelled out and the

effect on first term is not great so this is the reason why in our research we use three wires

47

324 Specimen Measurements

The tensile specimens used in this research are compliant of ASTM E8 Tensile parameters as shown

in figure 3-6

Fig 3-6 Tensile Specimen

Diameter

D(mm)

Gauge

Length

G(mm)

Smallest

Arc

Radius

R(mm)

Shortest

Area

A(mm)

Total

Length

L(mm)

Clamping

Area

Length

B(mm)

Clamping

Area

Diameter

C(mm)

Bar 125 02 625 01 gt10 gt75 ~ 145 ~ 35 20

Table 3-3 Specifications for Round Bar

33 Experiment Procedure

1 Attaching the Strain Gauge to the Tensile Specimen

(1) Prepare 1 ASTM E8 compliant tensile specimen round bar as shown in figure 3-7

(2) Prepare Strain Gauge as those described in table 3-4

(3) Prepare other consumables and adhesive agent such as epoxy adhesive or

cyanoacrylate adhesive as shown in figure 3-8

48

Fig 3-7 Actual Tensile Specimen

Fig 3-8 Other Materials Used (Such as Alcohol gauze transparent tape adhesive)

Gage Type

EA-06-120LZ-120E

Resistance in ohms at 24∘C

1200plusmn03

Gage Factor at 24∘C

2075plusmn05

Transverse Sensitivity at 24∘C

(+07plusmn02)

Table 3-4 Specifications for Strain Gauge

2 Attaching Strain Gauge

As shown in following figures we shall explain the attachment of the strain gauge

(1) Use sand paper and a rasp to clean thoroughly the surface where the strain gauge will be

attached to

49

(a)

(2) Use alcohol to wash the surface where the strain gauge will be attached and use gauze to rub

it off

(b)

(3) Find a clean surface and clean it with alcohol and gauze

(c)

(4) Place the strain gauge in the clean surface Use a piece of transparent tape on top of the strain

gauge after securely placed rip it off the surface carefully

50

(d)

(5) Use a piece of white paper to mark the place where the strain gauge will be attached and in

this way we can make sure that the strain gauge will be placed as horizontally and vertically

correct as possible

(e)

(6) In the place where we had our mark place the strain gauge

(f)

(7) Carefully lift one side of the tape and apply some of the adhesive agent to both the strain

gauge and specimenrsquos surface

(g)

51

(8) We need to make sure that the gauge and the specimen will be firmly attached so we gently

apply pressure with our thumb

(h)

(9) After the adhesive is fully dry we can carefully rip off the tape

(i)

(10) We need to do the whole process twice one for the horizontally placed strain gauge and one

for the vertically placed strain gauge

52

(j)

(11) We now proceed to solder the wires to the strain gauge

(k)

(12) After soldering we use a Volt Multimeter to measure that there is no contact between wires

If there is none then the specimen is ready for testing

(l)

(13) We now need to measure a 5cm distance and mark it to check and compare the elongation

before and after the tensile testing

(m)

53

Fig 3-9 Specimen-Strain Gauge Process

3 Tensile Test

(1) Enter the computer application that controls the tensile testing machine

(2) Turn on the tensile testing machine main switch

(3) Adjust the hydraulic pump to go back to its original position

(4) Bring the lowering motor down to a distance enough so as to attach the tensile specimen to the

system open the clamps and secure the specimen

(a)

(5) Connect all the necessary wires to the strain indicator equipment

54

(b)

(6) Start the ascending motor and wait for the expansion

(c)

Fig 3-10 Specimen-Tensile Testing Process

4 Start the Test

(1) Enter the software application and enter some variables needed for the experiment in the

specific screen

(2) Go back to the main screen and press the [測試] (measure) button to start the test and auto

recording in the software

(3) After the specimen breaks the mechanical device will automatically stop and ask the user to

enter the total displacement We take out the specimen from the testing machine and adjust the

machinersquos position back to its original position

(4) Save the results information

(5) Record the results from the strain indicator

34 Results

From this experiment we can get the Poissonrsquos Ratio Youngrsquos Modulus and Yield Strength etc and

because of the slippage phenomenon in the clamp at the moment of the test then the Elastic Limit will

display some yield phenomena So omit any undesirable results we just take the Yield portion of the

results as reference

In the process of the experiment the most important part to attend to is the attaching of the strain

gauge because the gaugersquos purpose is to measure the strain developed during the test and this strain

might be very small If the gaugersquos angle change during the test ie is not well attached this will affect

the accuracy of the measurements of Poissonrsquos ratio and Youngrsquos modulus

55

The materials provided by the manufacturer are SUM 23 and SUM 43 steel round bars and these two

types of materials have been through different heat treatment processes so they can be sub-divided

further into untreated material heat-treated material and black surface heat treated material for the two

materials with heat treatment the treatment process and finished are different In the end we only have

the mechanical properties that were calculated after our research of these materials

All of the specifications are identical to those shown in figure 3-6

341 SUM 23

Fig 3-11 SUM 23 Untreated Material

Number 7 10

Hardness(HRB) 74 75

Yield Stress (MPa) 448 440

Tensile Strength (MPa) 544 560

Poissonrsquos Ratio 029 027

Youngrsquos Modulus (GPa) 203 210

Cut-off Area Shrinking () 42 41

Elongation () 1125 1011

Table 3-5 Mechanical Properties of SUM 23 Untreated

56

Stress-Strain Diagram

(a)

(b)

57

Fig 3-12 Stress-Strain Diagrams for (a) 7 Round Bar and (b) 10 Round Bar

Cut-Off Area

(a)

(b)

Fig 3-13 Cut-Off Area of (a) 7 Round Bar and (b) 10 Round Bar

58

SUM 23 Nickel Round Bar

Fig 3-14 SUM 23 Nickel Material

Number 1 2 3 4

Hardness(HRB) 48 50 49 48

Yield Stress (MPa) 370 370 380 400

Tensile Strength (MPa) 455 451 450 450

Poissonrsquos Ratio 028 046 029 026

Youngrsquos Modulus (GPa) 243 303 246 206

Cut-off Area Shrinking () 803 803 726 601

Elongation () 566 65 602 647

Table 3-6 Mechanical Properties of SUM 23 Nickel

59

Stress-Strain Diagram

(a)

60

(b)

(c)

(d)

61

Fig 3-15 Stress-Strain Diagrams for (a) 1 Round Bar (b) 2 Round Bar (c) 3 Round Bar and (d)

4 Round Bar

Cut-Off Area

(a)

(b)

62

(c)

(d)

Fig 3-16 Cut-Off Area of (a) 1 Round Bar (b) 2 Round Bar (c) 3 Round Bar and (d) 4 Round

Bar

63

SUM 23 Black Surface Round Bar

Fig 3-17 SUM 23 Black Surface Material

Number 1 2 3

Hardness(HRB) 51 50 51

Yield Stress (MPa) 378 371 369

Tensile Strength (MPa) 467 465 464

Poissonrsquos Ratio 03 016 04

Youngrsquos Modulus (GPa) 215 266 266

Cut-off Area Shrinking () 986 94 848

Elongation () 748 805 761

Table 3-7 Mechanical Properties of SUM 23 Black Surface Material

64

Stress-Strain Diagram

(a)

(b)

65

(c)

Fig 3-18 Stress-Strain Diagrams for (a) 1 Round Bar 2 Round Bar and (c) 3 Round Bar

Cut-Off Surface

(a)

66

(b)

(c)

Fig 3-19 Cut-Off Surface of (a) 1 Round Bar 2 Round Bar and (c) 3 Round Bar

67

342 SUM 43

Fig 3-20 Untreated SUM 43 Untreated Material

Number 1 5

Hardness(HRB) 76 75

Yield Stress (MPa) 572 594

Tensile Strength (MPa) 743 785

Poissonrsquos Ratio 027 029

Youngrsquos Modulus (GPa) 200 202

Cut-off Area Shrinking () 338 2944

Elongation () 857 894

Table 3-8 Mechanical Properties of SUM 43 Untreated

68

Stress-Strain Diagrams

(a)

(b)

Fig 3-21 Stress-Strain Diagrams for SUM 43 (a) 1 Round Bar and (b) 5 Round Bar

69

Cut-Off Area

(a)

(b)

Fig 3-22 Cut-Off Area of SUM 43 (a) 1 Round Bar and (b) 5 Round Bar

70

SUM 43 Nickel Round Bar

Fig 3-23 SUM 43 Nickel Material

Number 4 5

Hardness(HRB) 51 50

Yield Stress (MPa) 1580 1544

Tensile Strength (MPa) 1639 1625

Poissonrsquos Ratio 03 028

Youngrsquos Modulus (GPa) 194 201

Cut-off Area Shrinking () 1697 137

Elongation () 376 265

Table 3-9 Mechanical Properties of SUM 43 Nickel

71

Stress-Strain Diagrams

(a)

(b)

Fig 3-24 Stress-Strain Diagrams for (a) 4 Round Bar and (b) 5 Round Bar

72

Cut-Off Area

(a)

(b)

Fig 3-25 Cut-Off Area of (a) 4 Round Bar and (b) 5 Round Bar

73

SUM 43 Black Surface Material

Fig 3-26 SUM 43 Black Surface Material

Number 3 5

Hardness(HRB) 56 56

Yield Stress (MPa) 1416 1361

Tensile Strength (MPa) 1591 1402

Poissonrsquos Ratio 029 031

Youngrsquos Modulus (GPa) 200 202

Cut-off Area Shrinking () 139 124

Elongation () 24 24

Table 3-10 Mechanical Properties of SUM 43 Black Surface Material

74

Stress-Strain Diagrams

0 2 4 6 8 10 12 14

-200

0

200

400

600

800

1000

1200

1400

1600

1800

應力 (MPa)

應變()

(a)

0 2 4 6 8 10

-200

0

200

400

600

800

1000

1200

1400

1600

應力

(MPa)

位移 ()

(b)

Fig 3-27 Stress-Strain Diagrams for (a) 3 Round Bar and (b) 5 Round Bar

(Note These curves were formulated using Visual Solutions Inc VisSim Software)

75

Cut-Off Area

(a)

(b)

Fig 3-28 Cut-Off Area of (a) 3 Round Bar and (b) 5 Round Bar

76

The force value (N) was retrieved from the Universal Testing Machine

The Poissonrsquos Ratio (ε) is calculated as

ε =

the values for the Poissonrsquos Ratio are in average around 0297

The Youngrsquos Modulus (E) is calculated as

E =

Where

Stress =

Cross-sectional Area =

where D is the Diameter

The value for D was in average around 1258 mm

The values shown by the computer because there is Slippage phenomena between the Clamp and the

specimen will not be taken into consideration for the elongation strain and Youngrsquos modulus and we will

refer to the values that we have meticulously calculated

77

Chapter 4 AR COATING IN DEPTH

41 Experimentrsquos Purpose and Principles

By means of a vacuum chamber and several other instruments we intend to apply Anti-Reflective

Coating using deposition process to a laser diode and in this way reduce its refraction so as to make it

lose less light in the process of amplification and we can control certain wavelengths we want produced

for certain desired applications in our case we are attempting to re-create a Bose-Einstein Condensate

An optimal BEC apparatus is shown in figure 4-1

Fig 4-1 BEC Apparatus

The main point of this experiment is to build a vacuum chamber system attach all the instrumentation

needed (Vacuum pump deposition meter and voltmeter) and use it to apply AR coating to a laser diode

After we have accomplished the AR coating other team will be in charge of designing the BEC apparatus

and use the results of our research

78

42 Experimentrsquos Equipment

421 Vacuum Chamber

For this research we designed a vacuum chamber whose main body is shown in figure 4-2 Its

dimensions are

Width 240 mm

Length 240 mm

Height 200 mm

Outer Diameter 4 in

Inner Diameter 15 in

Fig 4-2 Vacuum Chamber Main Body

The chamber is made up of 6 pass ways pass way A is the connection with the Laser Deposition

Equipment pass way B is the connection with the Turbo Pump and pass way C is for the connection with

the Deposition Source

A

C

B

79

Pass way C is for the deposition source as mentioned above This is a system where a thermal

resistance is heated by passing a high current through it which heats up a filament boat (made of tungsten)

where the material to be evaporated is place We control the temperature as such that the material will

evaporate and the heat will not cause the filament boat to crack

Because P = Isup2 R (where P is power I is current and R is resistance) to avoid the current to flow

where it is not desired we decided that the material for the Thermocouple shown in figure 4-3 should be

Copper ᴓ 63 mm We choose it that way because Copper has very good heat dissipation characteristics

and the resistance value is low It can reduce the value of the current enough to make the thermocouple to

create heat

Fig 4-3 Thermocouple

To the thermocouple we attach the tungsten filament boat We need to take notice of materials to be

used in this design because when using high current the tungsten filament boar will heat up and so the

material must be able to keep up with the heating potential of tungsten and has a low coefficient of heat

dissipation to avoid the tungsten to fail when heating up and therefore not evaporating Considering all

this we decide to use Stainless Steel

Because this clamp will be assembled inside the chamber after many revisions it was determined it

will have the shape shown in figure 4-4

Fig 4-4 Filament Boat Clamp Design

80

For the tungsten filament boat we bought the product from a distributor The dimensions are

Length 100 mm

Width 10 mm

Height 1 mm

Our thermocouple is 15 in but the pass way C is 4 in so we need to attach a Flange that connects

15in to 4in Because these specifications are quite difficult to achieve by Milling we had to use

electrical wire cutting

For the laser clamping system where the laser that is going to be AR coated will be placed will be

connected to pass way A the assembly is shown in figure 4-5 below

Fig 4-5 Cover Assembly

For this design we used an O-ring instead of a gasket so as to save time The design of the assembly

where the laser will be placed is shown in figure 4-6

Fig 4-6 Upper Cover Inner Assembly

D

E

F

81

Point D is the plate in the assembly where the laser diode will be fixed Because of the easy

processing we decide to use Aluminum and it is screwed to the top cover Point E is the connection for

the Quartz crystal resonator and it is designed in the same as point F in this way the results of the quartz

microbalance system will be more accurate in real time Point F is the final resting place for the laser

diode We use a Thor Labs Base with dimensions of ᴓ 9mm and ᴓ 56mm for two different size laser

diodes It just needs to be plugged in for easy installation

From figure 4-6 we know that the system needs signal system connections and because of the

change in temperature inside the chamber this could affect the functioning of the quartz microbalance so

we also need to install water tubes for cooling This is shown in figure 4-7 below

Fig 4-7 Diagram of Upper Cover Connections

In figure 4-8 we show the Feed through connections and their functions

Fig 4-8 Feed through Diagram

82

1 SQM-160 wire 5 Laser Connection 1 (Vin)

2 SQM-160 (G) 6 Laser Connection 2 (G)

3 K-Type-1 7 Laser Connection 3 (PD)

4 K-Type-2 8 Not In Use

The fully assembled chamber is shown in figure 4-9

Fig 4-9 Fully Assembled Chamber

422 Quartz Crystal Microbalance

For measuring the deposition on our target for coating we used the Inficon SQM-160 RateThickness

Monitor It is an easy to use instrument for measuring many types of thin-film coatings as shown in

figure 4-10

(a) Front Panel (b) Back Panel

Fig 4-10 Inficon SQM-160

83

Table 4-1 shows the technical specifications for this equipment

Number of sensors 2 Standard 4 additional optional

Sensor Frequency Range 40 MHz ~ 60 MHz

Reference Frequency Accuracy 002

Thickness Display Resolution 1 Aring

Thickness Resolution 015 Aring (Std) 0037 Aring (Hi Res)

Density of Stored Films 05-9999 gmcc

Tooling 10-399

Z-Factor 010-1000

Final Thickness 0000-9999k Aring

Measurement Period 15 to 2 sec

Simulation Mode Yes

Frequency Mode Yes

Rate Resolution 011 Arings

Dual Crystal Yes

Etch Mode Yes

Crystal Tooling 10-399

Crystal Fail Min Max 40 to 60 MHz 41 to 61 MHz

Power 100-120 200-240~plusmn10 nominal 20W

Operation Environment 0degC ~ 50degC

0 ~ 80 RH non-condensing

0 ~ 2000 meters

Class 1 Equipment

Pollution Degree 2

Rack Dimensions 885mm x 2127mm x 1969mm

Weight 27 kg

Table 4-1 Inficon SQM-160 RateThickness Monitor Specs

84

To the SQM-160 we need to connect an Oscillator We use the Sigma Instruments Remote Oscillator

Ser No 2 268 as shown in figure 4-11

Fig 4-11 Sigma Instruments Remote Oscillator

The connections diagram is shown in figure 4-12

Fig 4-12 SQM-160 Connections Diagram

85

423 Turbo Pump

For our experiments we used the Pfeiffer TCP 015 Electronic Drive Unit shown below in figure 4-13

Table 4-2 shows the technical specifications for this equipment

(a) Front Panel (b) Back Panel

Fig 4-13 Pfeiffer TCP 015 Electronic Drive

Connection Voltage (100V) 90-112

Mains Frequency 5060 Hz

Start-up Current 22 A

Nominal Frequency 1500 Hz

Rotation Speed 10V = 1500Hz plusmn2

Analog Output Current 10 V = 25 A plusmn 5

Rotation Speed Switchpoint 750 Hz

Works Setting 8 min

Permissible Ambient Temperature 0degC ~ 40degC

Dimensions Front Panel 1285mm x 1063mm

Insertion Length 227mm

Weight 27 Kg

Table 4-2 Pfeiffer TCP 015 Electronic Drive Specs

86

The connections diagram is shown in figure 4-14

Fig 4-14Connections Diagram for Pfeiffer TCP 015

To measure the pressure inside the chamber we use the Granville Phillips 375 Convectron Vacuum

Pressure Controller shown in figure 4-15

(a) Front Panel (b) Back Panel

Fig 4-15 Granville Phillips 375 Convectron

87

Its dimensions are shown in figure 4-16

Fig 4-16 Dimensions of Convectron

Table 4-3 shows the technical specifications for this equipment

Table 4-3 Granville Phillips 375 Convectron Vacuum Pressure Controller Specs

88

424 Multimeter

For our experiment we used the Keithley 2000 Digital Multimeter as shown in figure 4-17

(a) Front Panel (b) Back Panel

Fig 4-17 Keithley Model 2000 6-12-Digit Digital Multimeter

Its technical specifications are shown in table 4-4

Table 4-4 Keithley Model 2000 6-12-Digit Digital Multimeter Specs

89

43 Experiment Procedure

1 Connecting together the equipment and the chamber

(1) We first connect the resonator to the thickness monitor and connect the other side to the

chamber

(2) We now connect the flexible tubes to the turbo pump on one side and to the chamber on the

other

(3) We need to check that tubes are tightly connected to avoid any leaks in the vacuum pumping

process which will not allow us to get to our goal of Torr As shown in figure 4-18

(4) Connect the convectron to the system as shown in figure 4-19

Fig 4-18 checking for leaks using alcohol

Fig 4-19 Convectron attached to System

90

(5) Attach the clamps of the Multimeter to the bottom of the chamber as shown in figure 4-20

(6) Place the Quartz crystal in place

(7) Close tight vacuum chamber

(8) Connect all electrical appliances to power source

Fig 4-20 Multimeter Connections

2 Starting up the System

(1) We turn on all the devices as such Check all systems are ready to function Reset all values

that might be left over from previous tests

(2) Start the thickness monitor and set all values for this experiment In our case we got to testing

the system but not actual coating So we used the simulation mode of the thickness monitor as

shown in figure 4-21

Fig 4-21 Simulation Mode

91

(3) Start the turbo pump Make sure the lid on the vacuum chamber is tightly closed

(4) Start convectron and record initial pressure

(5) Start Multimeter and record initial current

3 Coating Process

(1) If we have the deposition material inside the filament boat the power source for the high

current must be started as well

(2) Record all initial values for thickness current pressure

(3) For an ideal experiment we need a thickness of around 101 nm a pressure of Torr and

a current of 300 A

44 Results

From previous experiments we have shown that we can turn a LED into a laser by means of AR

Coating In figure 4-22 shown below we can compare the actual results of a Diode before and after AR

coating From the blue line we can see that when the diode is at a current of 15mA its light will change

from LED to laser and if we look at the red line its critical current is around 30 to 35 mA

Fig 4-22 AR Coating Comparison for Laser Diodes

This means that the light emitted is not as strong as if the diode had been coated because inside the

chamber there must be some excitation first so the reflectivity of both sides inside the diode must be high

So because of the coating in one of the sides we have opened a door and let the light come out so the

critical current is risen as such and will be higher value than that of before the coating

92

In the following figures we can see the difference between before and after coating in a material The

thickness is around 1016 nm for this material

Fig 4-23 Before Coating

Fig 4-24 After Coating

93

Chapter 5 CONCLUSIONS AND RECOMMENDATIONS

51 Conclusions

For the first part of this independent study taking into consideration the data that came out of our

research and that sent by the provider we can say

1 SUM 23 after heat treatment will unexpectedly develop cracking in the middle of the tensile

testing process and suddenly break

2 Itrsquos possible that in the process of heat treatment to the SUM 23 material the treatment was not

uniform and this will create a pre-loaded moment force on one side that pushes on the other side

of the specimen resulting in material deformation

3 In the process of attaching the strain gauges to the materials it is very easy to make errors due to

poor adhesion or sudden removal in the tensile testing process

For our second part of the independent study the following can be made

1 At the beginning of this independent study we had no idea what Bose-Einstein Condensate was

or what was its purpose After much literature we finally comprehended the basic principles to

put into practice for our research

2 Our systemrsquos basic working principles and equipmentrsquos complexity are a little difficult to grasp

but hopefully we were able to understand enough of it

3 Theoretically from relation between the power and current we can know the advantages and

disadvantages of AR Coating

4 We were able to assemble the system and run test on its functions Even though we were able to

do this there is still much more work left to do with this system

52 Recommendations

For the Tensile Testing the following can be said

1 Ask the provider to check on the process of heat treatment on the SUM 23 material and give

them the information we have gathered through our test so they can correct for the mechanical

properties found if any change is needed

2 To avoid the problem of the inaccuracy of the poor adhesion of strain gauges we can attach

multiple strain gauges to the same one specimen so as to correlate data and improve our results

For the AR Coating the following can be said

1 We need to make sure that there are no physical defects on the main body of the chamber so as to

achieve maximum efficiency in the vacuum process If there was then the vacuum will arrive to

certain point and then start to decrease

2 It would be preferable to add some sort of visual aid that will allow the user to check the inside of

the chamber without actually opening it This will help us determine at what times we should

manipulate the current to better evaporate the substrate

94

REFERENCES

[1] A L Window Strain Gauge Technology Elsevier Applied Science London and New York 2nd

Edition 1992

[2] CC Perry and HR Lissner Strain Gauge Primer McGraw-Hill Book Co Inc New York 1955

[3] James W Dally William F Riley McGraw-Hill 1978

[4] University of Colorado Boulder BEC - What is it and where did the idea come from

httpwwwcoloradoeduphysics2000becwhat_is_ithtml

[5] Ultraslow Light amp Bose-Einstein Condensates Two-way Control with Coherent Light amp Atom

Fields Harvard Hau Lab Dr Lene Vestergaard Hau Optics amp Photonics News 16 1995

[6] The Art of Taming Light Ultra-slow and Stopped Light Harvard Hau Lab Dr Lene

Vestergaard Hau Europhysics News 2004

[7] Nonlinear Optics Shocking Superfluids Harvard Hau Lab Dr Lene Vestergaard Hau Nature

Physics 2007

[8] Model P3 Strain Indicator and Recorder Instruction Manual Vishay Micro-Measurements 2005

[9] Granville-Phillips Series 375 Convectron Vacuum Gauge Controller Instruction Manual Brooks

Automation 2008

[10] Effect of Film Thickness on the Validity of the Sauerbrey Equation for Hydrated Polyelectrolyte

Films Vogt Lin Wu White 2004

[11] Quartz Crystal Microbalance Study of DNA Immobilization and Hybridization for DNA Sensor

Development Chang Zhao 2008

[12] Installation of Strain Gages with SR-4 PrecoatAdhesive Vishay Micro-Measurements 2005

[13] Strain Gauge Measurement ndash A Tutorial National Instruments 1998

[14] Correlation between Vickers Hardness Number and Yield Stress of Cold-Formed Products

Yavuz Tekkaya

[15] httpsenwikipediaorg

Page 27: PC Hinge Materials Testing and AR Laser Diode Coating

27

reflected waves from the back of the glass medium will be half a wavelength out of phase So they

interfere destructively Because all reflected waves are interfered the maximum amount of light passes

through the coating Please refer to figure 2-15 to illustrate this idea

Fig 2-15 Light Passing through AR Coat and Glass

The most common process to attain this final product is by vacuum deposition For the best coating

results we need to lower the pressure inside the vacuum system to torr

Fig 2-16 Lens without (Top) and With (Bottom) AR Coating

28

233 Laser Diode Basic Principles

A laser diode is a laser whose active medium is a semiconductor similar to that found in

light-emitting diodes (LEDs) Please refer to figure 2-17 The most common type of laser diode is formed

from a p-n junction and powered by injected electric current

Fig 2-17 Laser Diode

Laser diodes are formed by doping a very thin layer on the surface of a crystal wafer The crystal is

doped to produce the n-type region and a p-type region one above the other

By referring to figure 1-2 we can see the basic structure of a working laser When the laser diode has

a current passing through it the light will get excited inside its gain medium and then will start to

resonate this process is called pumping The current exceeds the critical current and then it comes out as

laser light Please refer to figure 1-3 Since we use an external cavity laser we need to apply the AR

coating to the diode and adjust a diffraction grating The laser light comes out the diode and bounces on

the grating making the resonance externally and this becomes the ldquocavityrdquo as shown in figure 2-18

Fig 2-18 Tunable Laser Basic Configuration

29

The most important feature of the external cavity laser is that we can adjust the wavelength easily just

by changing the diffraction gratingrsquos angle and in the end this is the output wavelength of the laser For

different wavelengths there will be different levels of visible light as shown in figure 2-19

Fig 2-19 Light Spectrum

234 Quartz Microbalance System

A Quartz Crystal Microbalance is an instrument that measures a mass per unit area by measuring the

change in frequency of a quartz crystal resonator The resonance is disturbed by the addition or removal

of a small mass due to oxide growthdecay or film deposition (which is the case in our study) at the

surface of the acoustic resonator The QCM can be used under vacuum in gas phase and more recently in

liquid environments It is useful for monitoring the rate of deposition in thin film deposition systems

under vacuum Frequency measurements are easily made with high precision

For our research we used the Sigma Instruments SQM-160 RateThickness Monitor shown in figure

2-20

Fig 2-20 Front and Back Panels of SQM-160

30

The microbalance uses Quartz as the resonator Quartz is one member of the family of crystals that

experience the Piezoelectric Effect

Piezoelectricity is the charge that accumulates in certain solid materials in response to applied

mechanical stress It means electricity resulting from pressure It was discovered in 1880 by Jacques and

Pierre Curie It is understood as the linear electromechanical interaction between the mechanical and the

electrical state in crystalline materials with no inversion symmetry It is a reversible process in that

materials exhibiting direct piezoelectricity also exhibit the reverse This means that the internal generation

of electrical resulting from applied mechanical force and vice versa

By using the piezoelectric effect we can probe as an acoustic resonance by electrical means Applying

alternating current to the quartz crystal induces oscillations This creates a shear wave We can use these

qualities to determine the resonance frequency at high accuracy

The frequency of oscillation of the crystal is partially dependent in the thickness of the crystal During

normal operation all the variables are held constant so a change in thickness correlates directly to a

change in frequency As mass is deposited or etched away the thickness increases or decreases and so the

frequency of oscillation changes accordingly With some simplifying assumptions the frequency change

can be quantified and correlated precisely to the mass change using the Sauerbreyrsquos Equation

Developed by G Sauerbrey in 1959 it is a method for correlating changes in the oscillation

frequency of a piezoelectric crystal with the mass deposited on it It is defined as below

Where f0 is the Resonant frequency Δf is the Frequency change Δm is the mass change A is the

piezoelectrically active area of the crystal q is the Density of quartz (2648 gcmsup3) and μq is the Shear

modulus of quarts(2947x gcmssup2)

Because the film is treated as an extension of thickness Sauerbreyrsquos equation only applies to systems

in which the following 3 conditions are met

Deposited mass must be rigid

Deposited mass must be distributed evenly

The frequency change

lt002

If the change is greater than 2 the Z-match method must be used to determine the change in mass

It is defined as

Where fL is the frequency of the loaded crystal fU is the resonant frequency Nq is the frequency

constant (1668x HzAring) Δm is the mass change A is the piezoelectrically active area of the crystal

31

q is the density of quartz Z is the method constant f is the density of film μq Is the shear modulus of

quarts and μf is the shear modulus of film

The Sauerbrey equation cannot be applied to systems under liquid medium

The crystals are seed crystals plated with gold on both top and bottom for applications A crystal is

shown in figure 2-21 The QCM consists of a thin piezoelectric plate with electrodes evaporated on both

sides Due to the piezoelectric effect AC voltage across the electrodes induces a shear deformation and

vice versa The electromechanical coupling provides a simple way to detect an acoustic resonance by

electrical means

The Z also called Z-factor is a constant value for different materials and it is shown together with the

density of different materials in table 2-2 below

Fig 2-21 QCM Crystals

The Oscillator of the SQM-160 is shown in figure 2-22 and the equivalent circuit for the Resonant

Oscillator is shown in figure 2-23

Fig 2-22 SQM-160 Oscillator

32

Fig 2-23 Oscillator Circuit

33

Table 2-2 Z-Ratios for Different Materials

Table 2-2 Continued

34

Table 2-2 Continued

35

Table 2-2 Continued

36

Table 2-2 Continued

37

Table 2-2 Continued

38

Table 2-2 Continued

235 Vacuum Chamber System

Vacuum Evaporation is the process of depositing thin films of materials onto surfaces The technique

consists of pumping a vacuum chamber to pressures of less than torr and heating a material to

produce a flux of vapor in order to deposit the material onto a surface The material to be vaporized is

typically heated until its vapor pressure is high enough to produce a flux several Angstrom per second by

using an electrically resistive heater or bombardment by a high voltage beam The process was invented

by Henri Nestle in 1886 for food industry

In here the system has been pumped to a vacuum of Torr When a high current is passed

through the filament boat the filament boat is heated over the desired metal evaporation temperature and

so evaporation starts When the evaporation process is finished and the metal cools down crystals

condensate in the surface of the wafer From the weight of the evaporated material the distance between

the filament boat and the wafer we are able to calculate the deposition thickness and we can also use the

mass detector follower like the Quartz crystal resonator microbalance system In the process of

evaporation we usually use a board in between the filament boat and the wafer This is because before we

arrive to the desired evaporation temperature there will be some impurities that will be vaporized in the

controlled environment so we first use a small current and the board in between to get rid of those

impurities and this raises the purity of the deposition material

39

A vacuum evaporation system is shown in figure 2-24

Fig 2-24 Vacuum Evaporation System

Rough Vacuum 760 ~ 1 torr

Medium Vacuum 1 ~ torr

High Vacuum ~ torr

Ultra-High Vacuum Lower than torr

Table 2-3 Classification of Vacuum

For our study we need to use a Turbo Pump A regular turbo pump is shown in figure 2-25

Fig 2-25 Turbo Pump

For our research we used the Pfeiffer TCP 015 Electronic Drive Unit and Granville Phillips 375

Convectron shown below in figure 2-26

40

Fig 2-26 Control and Measurement Equipment

The electronic drive controls the turbo pump and the Convectron measures the pressure inside our

chamber The turbo pump is a type of vacuum pump used to maintain high vacuum Most turbo pumps

are centrifugal When we start the pumping we need to use a mechanical pump so as to decrease the

pressure inside the system from constant atmospheric pressure to torr and then the use dispersion

pump to continue the vacuum until we get to the desired pressure We need to notice though when we

start the dispersion pump we canrsquot turn off the mechanical pump and they both need to run together If

we need to turn off the pumping we first turn off the dispersion pump wait for it to completely stop and

then turn off the mechanical pump

Our completely assembled system is shown in figure 2-27 below

Fig 2-27 Complete System

41

Chapter 3 TENSILE TESTING IN DEPTH

31 Experimentrsquos Purpose and Principles

By means of Universal testing machine and Strain gauges we were able to observe discuss and

analyze the phenomena created when a specimen of certain material is manipulated under an external load

and determine the stress strain and deformation values later we can use the graphing methods of

stress-strain diagram to describe it

The main point of this experiment is that after the tensile specimen is tested use computer analysis

and the actual strain data and after statistical adjustment make the final results report (Tensile testing

experiment is in accordance with ASTM E8)

32 Experimentrsquos Equipment

321 Universal Testing Machine

For the materials testing experiment part of this research we use a Universal Testing Machine as

shown in figure 31 The maximum load it can apply is 100 Ton After the test specimen is secured on the

device with the use of instrumentation the load exerted and the effects of this become apparent on the

specimen and even the smallest of changes can be recorded For our research we used the Chun Yen

Testing Machines Co Ltd 100 Ton Micro Computer Universal Tensile Tester

Fig 31 Universal Testing Machine

42

Table 31 shows the specifications for this machine

Max Capacity 100 Ton

Accuracy plusmn1

Tension (mm) Max Space 1150mm

Grip for Rod 20-70mm

Ram Stroke 250mm

Effective Column Interval 940mm

Crosshead Speed 300mmmin

Testing Speed 0-50mmmin

Volume of Machine 1700times1000times3350mm(LtimesWtimesH)

Volume of Control Panel 1000times800times1500mm(LtimesWtimesH)

Weight 8000kg

Power 3∮220V 20A

Computer AMD K6-2-350

OS Windows XP

Screen 15rdquo CRT

Table 3-1 Chun Yen Testing Machine Specs Table

The connections diagram is shown in figure 3-2

Fig 3-2 Diagram for System Connections

43

When the test specimen is placed when the external force is applied the Load Cell can measure the

size of the applied force and the Encoder measures the expansion rate of change The Local Controller

receives all the information from the 2 units after arranging the results they are displayed in the

computer and they can be afterwards submitted for more complex analysis such as Finite Element

Analysis and we can get the Stress-Strain Diagram

322 Strain Measurement Equipment

The equipment used in our research provides a four-channel measurement that means we can use up

to 4 strain gauges at a time to do our measurements and provides 3 different bridge arrangements as

shown in figure 3-3

(a) (b) (c)

Fig 3-3 Input Connections for Strain Indicator

Figure 3-3 (a) is the Quarter Bridge (b) is the Half Bridge and (c) is the Full Bridge and Transducers

For our study we used the Quarter Bridge and use the Strain Gauge values to decide the position of the

connecting wires The Strain indicator is shown in figure 3-4

Fig 3-4 Vishay Micro-Measurements Model P3 Strain Indicator and Recorder

44

Input Connections Tool Free eccentric lever release

4-channel input

Wire diameter16-28AWG

Bridge Configurations Quarter- Half- and Full Bridge

Bridge Impedance 60-2000Ω

Display 128 64 pixel FSTN positive gray LCD

Data Conversion AD Converter filter

Measurement Range Resolution Strain Range plusmn155mVV

Resolution plusmn00005mVV

Measurement Accuracy plusmn01 of reading plusmn3 counts

Gage Factor Control 0500-9900

Balance Control Software either manual or automatic

Bridge Excitation 15VDC nominal

Communication Interface USB Cable Included

Data Storage Removable Media Card

Shunt Calibration Across bridge completion resistors controlled

by software When Gage Factor=200

120Ω350Ω1000Ω

Analog Output Value 0 to 25V max

Ranges plusmn320 microε plusmn3200 microε plusmn32000 microε

Error 05 output voltage +5mV

Max Error 14 output voltage + 20mV

Update rate 480 samplessec

Output Load 2000Ω

Power Battery Two Alkaline D cells

Battery life 400 hours typ

USB 5V 100mA

Operational Environment Temperature 0-50

Humidity Up to 90 Non-condensing

Case Aluminum Alloy

Size and Weight 228times152times152(mm) 20(kg)

Table 3-2 Vishay Micro-Measurements Model P3 Strain Indicator and Recorder Specs

45

323 Strain Gauge

The strain gaugersquos main basic principle is to use a resistancersquos characteristics to measure the strain

The inside connections of the strain indicator are shown in figure 3-5

Fig 3-5 Inner Connections

As shown above this is a quarter-bridge connection We connect equal-length 3 wires to the 2

connections allowed by the strain gauge wire 1 and 3 can be used to cancel out the effects of temperature

to the resistance and because of the addition of wires 1 and 3 wire 2 can directly measure the experiment

results from the strain gauge and therefore the strain developed with no influence of temperature

If there were no two measuring leads then the relations will be

R 4 =R g +2R L

Where Rg is the Strain Gauge Value and RL is the wire resistance then

4

4

R

R=

Lg

g

RR

R

2

=

gL

gg

RR

RR

21

amp

4

4

R

R=

g

g

R

R(1- L)

Where L is the Signal Loss Factor and so

L =gL

gL

RR

RR

21

2

g

L

R

2R if

g

L

R

2Rltlt1

46

(Actual Value R g =120R L =08g

L

R

2Ris always much smaller than 1)

R 4 =R g +2R LR 2 =R 3 =rR gR 1 =R g 32 RR =0

V 0 =V 2)1( r

r

(

4

4

R

R-

1

1

R

R)

The first term describes loss attenuation effects second term describes loss of balancing capabilities

effects

V 0 =V 2)1( r

r

[

)2

(Lg

g

RR

R

+

T

Lg

g

RR

R

)

2( + T

Lg

L

RR

R

)

2

2( -(

g

g

R

R) T ]

The first term describes loss attenuation effects and loss of balancing capabilities effects the second

third and fourth terms describe the temperature effects on the wire

For the three-wire method we have

L =gL

gL

RR

RR

1

g

L

R

R if

g

L

R

Rltlt1

V 0 =V 2)1( r

r

[

)(Lg

g

RR

R

+

T

Lg

g

RR

R

)( + T

Lg

L

RR

R

)

2( -

T

Lg

g

RR

R

)( - T

Lg

L

RR

R

)

2( ]

V 0 = V2)1( r

r

)(

Lg

g

RR

R

In the last four terms inside parenthesis we can see the effects of temperature being cancelled out and the

effect on first term is not great so this is the reason why in our research we use three wires

47

324 Specimen Measurements

The tensile specimens used in this research are compliant of ASTM E8 Tensile parameters as shown

in figure 3-6

Fig 3-6 Tensile Specimen

Diameter

D(mm)

Gauge

Length

G(mm)

Smallest

Arc

Radius

R(mm)

Shortest

Area

A(mm)

Total

Length

L(mm)

Clamping

Area

Length

B(mm)

Clamping

Area

Diameter

C(mm)

Bar 125 02 625 01 gt10 gt75 ~ 145 ~ 35 20

Table 3-3 Specifications for Round Bar

33 Experiment Procedure

1 Attaching the Strain Gauge to the Tensile Specimen

(1) Prepare 1 ASTM E8 compliant tensile specimen round bar as shown in figure 3-7

(2) Prepare Strain Gauge as those described in table 3-4

(3) Prepare other consumables and adhesive agent such as epoxy adhesive or

cyanoacrylate adhesive as shown in figure 3-8

48

Fig 3-7 Actual Tensile Specimen

Fig 3-8 Other Materials Used (Such as Alcohol gauze transparent tape adhesive)

Gage Type

EA-06-120LZ-120E

Resistance in ohms at 24∘C

1200plusmn03

Gage Factor at 24∘C

2075plusmn05

Transverse Sensitivity at 24∘C

(+07plusmn02)

Table 3-4 Specifications for Strain Gauge

2 Attaching Strain Gauge

As shown in following figures we shall explain the attachment of the strain gauge

(1) Use sand paper and a rasp to clean thoroughly the surface where the strain gauge will be

attached to

49

(a)

(2) Use alcohol to wash the surface where the strain gauge will be attached and use gauze to rub

it off

(b)

(3) Find a clean surface and clean it with alcohol and gauze

(c)

(4) Place the strain gauge in the clean surface Use a piece of transparent tape on top of the strain

gauge after securely placed rip it off the surface carefully

50

(d)

(5) Use a piece of white paper to mark the place where the strain gauge will be attached and in

this way we can make sure that the strain gauge will be placed as horizontally and vertically

correct as possible

(e)

(6) In the place where we had our mark place the strain gauge

(f)

(7) Carefully lift one side of the tape and apply some of the adhesive agent to both the strain

gauge and specimenrsquos surface

(g)

51

(8) We need to make sure that the gauge and the specimen will be firmly attached so we gently

apply pressure with our thumb

(h)

(9) After the adhesive is fully dry we can carefully rip off the tape

(i)

(10) We need to do the whole process twice one for the horizontally placed strain gauge and one

for the vertically placed strain gauge

52

(j)

(11) We now proceed to solder the wires to the strain gauge

(k)

(12) After soldering we use a Volt Multimeter to measure that there is no contact between wires

If there is none then the specimen is ready for testing

(l)

(13) We now need to measure a 5cm distance and mark it to check and compare the elongation

before and after the tensile testing

(m)

53

Fig 3-9 Specimen-Strain Gauge Process

3 Tensile Test

(1) Enter the computer application that controls the tensile testing machine

(2) Turn on the tensile testing machine main switch

(3) Adjust the hydraulic pump to go back to its original position

(4) Bring the lowering motor down to a distance enough so as to attach the tensile specimen to the

system open the clamps and secure the specimen

(a)

(5) Connect all the necessary wires to the strain indicator equipment

54

(b)

(6) Start the ascending motor and wait for the expansion

(c)

Fig 3-10 Specimen-Tensile Testing Process

4 Start the Test

(1) Enter the software application and enter some variables needed for the experiment in the

specific screen

(2) Go back to the main screen and press the [測試] (measure) button to start the test and auto

recording in the software

(3) After the specimen breaks the mechanical device will automatically stop and ask the user to

enter the total displacement We take out the specimen from the testing machine and adjust the

machinersquos position back to its original position

(4) Save the results information

(5) Record the results from the strain indicator

34 Results

From this experiment we can get the Poissonrsquos Ratio Youngrsquos Modulus and Yield Strength etc and

because of the slippage phenomenon in the clamp at the moment of the test then the Elastic Limit will

display some yield phenomena So omit any undesirable results we just take the Yield portion of the

results as reference

In the process of the experiment the most important part to attend to is the attaching of the strain

gauge because the gaugersquos purpose is to measure the strain developed during the test and this strain

might be very small If the gaugersquos angle change during the test ie is not well attached this will affect

the accuracy of the measurements of Poissonrsquos ratio and Youngrsquos modulus

55

The materials provided by the manufacturer are SUM 23 and SUM 43 steel round bars and these two

types of materials have been through different heat treatment processes so they can be sub-divided

further into untreated material heat-treated material and black surface heat treated material for the two

materials with heat treatment the treatment process and finished are different In the end we only have

the mechanical properties that were calculated after our research of these materials

All of the specifications are identical to those shown in figure 3-6

341 SUM 23

Fig 3-11 SUM 23 Untreated Material

Number 7 10

Hardness(HRB) 74 75

Yield Stress (MPa) 448 440

Tensile Strength (MPa) 544 560

Poissonrsquos Ratio 029 027

Youngrsquos Modulus (GPa) 203 210

Cut-off Area Shrinking () 42 41

Elongation () 1125 1011

Table 3-5 Mechanical Properties of SUM 23 Untreated

56

Stress-Strain Diagram

(a)

(b)

57

Fig 3-12 Stress-Strain Diagrams for (a) 7 Round Bar and (b) 10 Round Bar

Cut-Off Area

(a)

(b)

Fig 3-13 Cut-Off Area of (a) 7 Round Bar and (b) 10 Round Bar

58

SUM 23 Nickel Round Bar

Fig 3-14 SUM 23 Nickel Material

Number 1 2 3 4

Hardness(HRB) 48 50 49 48

Yield Stress (MPa) 370 370 380 400

Tensile Strength (MPa) 455 451 450 450

Poissonrsquos Ratio 028 046 029 026

Youngrsquos Modulus (GPa) 243 303 246 206

Cut-off Area Shrinking () 803 803 726 601

Elongation () 566 65 602 647

Table 3-6 Mechanical Properties of SUM 23 Nickel

59

Stress-Strain Diagram

(a)

60

(b)

(c)

(d)

61

Fig 3-15 Stress-Strain Diagrams for (a) 1 Round Bar (b) 2 Round Bar (c) 3 Round Bar and (d)

4 Round Bar

Cut-Off Area

(a)

(b)

62

(c)

(d)

Fig 3-16 Cut-Off Area of (a) 1 Round Bar (b) 2 Round Bar (c) 3 Round Bar and (d) 4 Round

Bar

63

SUM 23 Black Surface Round Bar

Fig 3-17 SUM 23 Black Surface Material

Number 1 2 3

Hardness(HRB) 51 50 51

Yield Stress (MPa) 378 371 369

Tensile Strength (MPa) 467 465 464

Poissonrsquos Ratio 03 016 04

Youngrsquos Modulus (GPa) 215 266 266

Cut-off Area Shrinking () 986 94 848

Elongation () 748 805 761

Table 3-7 Mechanical Properties of SUM 23 Black Surface Material

64

Stress-Strain Diagram

(a)

(b)

65

(c)

Fig 3-18 Stress-Strain Diagrams for (a) 1 Round Bar 2 Round Bar and (c) 3 Round Bar

Cut-Off Surface

(a)

66

(b)

(c)

Fig 3-19 Cut-Off Surface of (a) 1 Round Bar 2 Round Bar and (c) 3 Round Bar

67

342 SUM 43

Fig 3-20 Untreated SUM 43 Untreated Material

Number 1 5

Hardness(HRB) 76 75

Yield Stress (MPa) 572 594

Tensile Strength (MPa) 743 785

Poissonrsquos Ratio 027 029

Youngrsquos Modulus (GPa) 200 202

Cut-off Area Shrinking () 338 2944

Elongation () 857 894

Table 3-8 Mechanical Properties of SUM 43 Untreated

68

Stress-Strain Diagrams

(a)

(b)

Fig 3-21 Stress-Strain Diagrams for SUM 43 (a) 1 Round Bar and (b) 5 Round Bar

69

Cut-Off Area

(a)

(b)

Fig 3-22 Cut-Off Area of SUM 43 (a) 1 Round Bar and (b) 5 Round Bar

70

SUM 43 Nickel Round Bar

Fig 3-23 SUM 43 Nickel Material

Number 4 5

Hardness(HRB) 51 50

Yield Stress (MPa) 1580 1544

Tensile Strength (MPa) 1639 1625

Poissonrsquos Ratio 03 028

Youngrsquos Modulus (GPa) 194 201

Cut-off Area Shrinking () 1697 137

Elongation () 376 265

Table 3-9 Mechanical Properties of SUM 43 Nickel

71

Stress-Strain Diagrams

(a)

(b)

Fig 3-24 Stress-Strain Diagrams for (a) 4 Round Bar and (b) 5 Round Bar

72

Cut-Off Area

(a)

(b)

Fig 3-25 Cut-Off Area of (a) 4 Round Bar and (b) 5 Round Bar

73

SUM 43 Black Surface Material

Fig 3-26 SUM 43 Black Surface Material

Number 3 5

Hardness(HRB) 56 56

Yield Stress (MPa) 1416 1361

Tensile Strength (MPa) 1591 1402

Poissonrsquos Ratio 029 031

Youngrsquos Modulus (GPa) 200 202

Cut-off Area Shrinking () 139 124

Elongation () 24 24

Table 3-10 Mechanical Properties of SUM 43 Black Surface Material

74

Stress-Strain Diagrams

0 2 4 6 8 10 12 14

-200

0

200

400

600

800

1000

1200

1400

1600

1800

應力 (MPa)

應變()

(a)

0 2 4 6 8 10

-200

0

200

400

600

800

1000

1200

1400

1600

應力

(MPa)

位移 ()

(b)

Fig 3-27 Stress-Strain Diagrams for (a) 3 Round Bar and (b) 5 Round Bar

(Note These curves were formulated using Visual Solutions Inc VisSim Software)

75

Cut-Off Area

(a)

(b)

Fig 3-28 Cut-Off Area of (a) 3 Round Bar and (b) 5 Round Bar

76

The force value (N) was retrieved from the Universal Testing Machine

The Poissonrsquos Ratio (ε) is calculated as

ε =

the values for the Poissonrsquos Ratio are in average around 0297

The Youngrsquos Modulus (E) is calculated as

E =

Where

Stress =

Cross-sectional Area =

where D is the Diameter

The value for D was in average around 1258 mm

The values shown by the computer because there is Slippage phenomena between the Clamp and the

specimen will not be taken into consideration for the elongation strain and Youngrsquos modulus and we will

refer to the values that we have meticulously calculated

77

Chapter 4 AR COATING IN DEPTH

41 Experimentrsquos Purpose and Principles

By means of a vacuum chamber and several other instruments we intend to apply Anti-Reflective

Coating using deposition process to a laser diode and in this way reduce its refraction so as to make it

lose less light in the process of amplification and we can control certain wavelengths we want produced

for certain desired applications in our case we are attempting to re-create a Bose-Einstein Condensate

An optimal BEC apparatus is shown in figure 4-1

Fig 4-1 BEC Apparatus

The main point of this experiment is to build a vacuum chamber system attach all the instrumentation

needed (Vacuum pump deposition meter and voltmeter) and use it to apply AR coating to a laser diode

After we have accomplished the AR coating other team will be in charge of designing the BEC apparatus

and use the results of our research

78

42 Experimentrsquos Equipment

421 Vacuum Chamber

For this research we designed a vacuum chamber whose main body is shown in figure 4-2 Its

dimensions are

Width 240 mm

Length 240 mm

Height 200 mm

Outer Diameter 4 in

Inner Diameter 15 in

Fig 4-2 Vacuum Chamber Main Body

The chamber is made up of 6 pass ways pass way A is the connection with the Laser Deposition

Equipment pass way B is the connection with the Turbo Pump and pass way C is for the connection with

the Deposition Source

A

C

B

79

Pass way C is for the deposition source as mentioned above This is a system where a thermal

resistance is heated by passing a high current through it which heats up a filament boat (made of tungsten)

where the material to be evaporated is place We control the temperature as such that the material will

evaporate and the heat will not cause the filament boat to crack

Because P = Isup2 R (where P is power I is current and R is resistance) to avoid the current to flow

where it is not desired we decided that the material for the Thermocouple shown in figure 4-3 should be

Copper ᴓ 63 mm We choose it that way because Copper has very good heat dissipation characteristics

and the resistance value is low It can reduce the value of the current enough to make the thermocouple to

create heat

Fig 4-3 Thermocouple

To the thermocouple we attach the tungsten filament boat We need to take notice of materials to be

used in this design because when using high current the tungsten filament boar will heat up and so the

material must be able to keep up with the heating potential of tungsten and has a low coefficient of heat

dissipation to avoid the tungsten to fail when heating up and therefore not evaporating Considering all

this we decide to use Stainless Steel

Because this clamp will be assembled inside the chamber after many revisions it was determined it

will have the shape shown in figure 4-4

Fig 4-4 Filament Boat Clamp Design

80

For the tungsten filament boat we bought the product from a distributor The dimensions are

Length 100 mm

Width 10 mm

Height 1 mm

Our thermocouple is 15 in but the pass way C is 4 in so we need to attach a Flange that connects

15in to 4in Because these specifications are quite difficult to achieve by Milling we had to use

electrical wire cutting

For the laser clamping system where the laser that is going to be AR coated will be placed will be

connected to pass way A the assembly is shown in figure 4-5 below

Fig 4-5 Cover Assembly

For this design we used an O-ring instead of a gasket so as to save time The design of the assembly

where the laser will be placed is shown in figure 4-6

Fig 4-6 Upper Cover Inner Assembly

D

E

F

81

Point D is the plate in the assembly where the laser diode will be fixed Because of the easy

processing we decide to use Aluminum and it is screwed to the top cover Point E is the connection for

the Quartz crystal resonator and it is designed in the same as point F in this way the results of the quartz

microbalance system will be more accurate in real time Point F is the final resting place for the laser

diode We use a Thor Labs Base with dimensions of ᴓ 9mm and ᴓ 56mm for two different size laser

diodes It just needs to be plugged in for easy installation

From figure 4-6 we know that the system needs signal system connections and because of the

change in temperature inside the chamber this could affect the functioning of the quartz microbalance so

we also need to install water tubes for cooling This is shown in figure 4-7 below

Fig 4-7 Diagram of Upper Cover Connections

In figure 4-8 we show the Feed through connections and their functions

Fig 4-8 Feed through Diagram

82

1 SQM-160 wire 5 Laser Connection 1 (Vin)

2 SQM-160 (G) 6 Laser Connection 2 (G)

3 K-Type-1 7 Laser Connection 3 (PD)

4 K-Type-2 8 Not In Use

The fully assembled chamber is shown in figure 4-9

Fig 4-9 Fully Assembled Chamber

422 Quartz Crystal Microbalance

For measuring the deposition on our target for coating we used the Inficon SQM-160 RateThickness

Monitor It is an easy to use instrument for measuring many types of thin-film coatings as shown in

figure 4-10

(a) Front Panel (b) Back Panel

Fig 4-10 Inficon SQM-160

83

Table 4-1 shows the technical specifications for this equipment

Number of sensors 2 Standard 4 additional optional

Sensor Frequency Range 40 MHz ~ 60 MHz

Reference Frequency Accuracy 002

Thickness Display Resolution 1 Aring

Thickness Resolution 015 Aring (Std) 0037 Aring (Hi Res)

Density of Stored Films 05-9999 gmcc

Tooling 10-399

Z-Factor 010-1000

Final Thickness 0000-9999k Aring

Measurement Period 15 to 2 sec

Simulation Mode Yes

Frequency Mode Yes

Rate Resolution 011 Arings

Dual Crystal Yes

Etch Mode Yes

Crystal Tooling 10-399

Crystal Fail Min Max 40 to 60 MHz 41 to 61 MHz

Power 100-120 200-240~plusmn10 nominal 20W

Operation Environment 0degC ~ 50degC

0 ~ 80 RH non-condensing

0 ~ 2000 meters

Class 1 Equipment

Pollution Degree 2

Rack Dimensions 885mm x 2127mm x 1969mm

Weight 27 kg

Table 4-1 Inficon SQM-160 RateThickness Monitor Specs

84

To the SQM-160 we need to connect an Oscillator We use the Sigma Instruments Remote Oscillator

Ser No 2 268 as shown in figure 4-11

Fig 4-11 Sigma Instruments Remote Oscillator

The connections diagram is shown in figure 4-12

Fig 4-12 SQM-160 Connections Diagram

85

423 Turbo Pump

For our experiments we used the Pfeiffer TCP 015 Electronic Drive Unit shown below in figure 4-13

Table 4-2 shows the technical specifications for this equipment

(a) Front Panel (b) Back Panel

Fig 4-13 Pfeiffer TCP 015 Electronic Drive

Connection Voltage (100V) 90-112

Mains Frequency 5060 Hz

Start-up Current 22 A

Nominal Frequency 1500 Hz

Rotation Speed 10V = 1500Hz plusmn2

Analog Output Current 10 V = 25 A plusmn 5

Rotation Speed Switchpoint 750 Hz

Works Setting 8 min

Permissible Ambient Temperature 0degC ~ 40degC

Dimensions Front Panel 1285mm x 1063mm

Insertion Length 227mm

Weight 27 Kg

Table 4-2 Pfeiffer TCP 015 Electronic Drive Specs

86

The connections diagram is shown in figure 4-14

Fig 4-14Connections Diagram for Pfeiffer TCP 015

To measure the pressure inside the chamber we use the Granville Phillips 375 Convectron Vacuum

Pressure Controller shown in figure 4-15

(a) Front Panel (b) Back Panel

Fig 4-15 Granville Phillips 375 Convectron

87

Its dimensions are shown in figure 4-16

Fig 4-16 Dimensions of Convectron

Table 4-3 shows the technical specifications for this equipment

Table 4-3 Granville Phillips 375 Convectron Vacuum Pressure Controller Specs

88

424 Multimeter

For our experiment we used the Keithley 2000 Digital Multimeter as shown in figure 4-17

(a) Front Panel (b) Back Panel

Fig 4-17 Keithley Model 2000 6-12-Digit Digital Multimeter

Its technical specifications are shown in table 4-4

Table 4-4 Keithley Model 2000 6-12-Digit Digital Multimeter Specs

89

43 Experiment Procedure

1 Connecting together the equipment and the chamber

(1) We first connect the resonator to the thickness monitor and connect the other side to the

chamber

(2) We now connect the flexible tubes to the turbo pump on one side and to the chamber on the

other

(3) We need to check that tubes are tightly connected to avoid any leaks in the vacuum pumping

process which will not allow us to get to our goal of Torr As shown in figure 4-18

(4) Connect the convectron to the system as shown in figure 4-19

Fig 4-18 checking for leaks using alcohol

Fig 4-19 Convectron attached to System

90

(5) Attach the clamps of the Multimeter to the bottom of the chamber as shown in figure 4-20

(6) Place the Quartz crystal in place

(7) Close tight vacuum chamber

(8) Connect all electrical appliances to power source

Fig 4-20 Multimeter Connections

2 Starting up the System

(1) We turn on all the devices as such Check all systems are ready to function Reset all values

that might be left over from previous tests

(2) Start the thickness monitor and set all values for this experiment In our case we got to testing

the system but not actual coating So we used the simulation mode of the thickness monitor as

shown in figure 4-21

Fig 4-21 Simulation Mode

91

(3) Start the turbo pump Make sure the lid on the vacuum chamber is tightly closed

(4) Start convectron and record initial pressure

(5) Start Multimeter and record initial current

3 Coating Process

(1) If we have the deposition material inside the filament boat the power source for the high

current must be started as well

(2) Record all initial values for thickness current pressure

(3) For an ideal experiment we need a thickness of around 101 nm a pressure of Torr and

a current of 300 A

44 Results

From previous experiments we have shown that we can turn a LED into a laser by means of AR

Coating In figure 4-22 shown below we can compare the actual results of a Diode before and after AR

coating From the blue line we can see that when the diode is at a current of 15mA its light will change

from LED to laser and if we look at the red line its critical current is around 30 to 35 mA

Fig 4-22 AR Coating Comparison for Laser Diodes

This means that the light emitted is not as strong as if the diode had been coated because inside the

chamber there must be some excitation first so the reflectivity of both sides inside the diode must be high

So because of the coating in one of the sides we have opened a door and let the light come out so the

critical current is risen as such and will be higher value than that of before the coating

92

In the following figures we can see the difference between before and after coating in a material The

thickness is around 1016 nm for this material

Fig 4-23 Before Coating

Fig 4-24 After Coating

93

Chapter 5 CONCLUSIONS AND RECOMMENDATIONS

51 Conclusions

For the first part of this independent study taking into consideration the data that came out of our

research and that sent by the provider we can say

1 SUM 23 after heat treatment will unexpectedly develop cracking in the middle of the tensile

testing process and suddenly break

2 Itrsquos possible that in the process of heat treatment to the SUM 23 material the treatment was not

uniform and this will create a pre-loaded moment force on one side that pushes on the other side

of the specimen resulting in material deformation

3 In the process of attaching the strain gauges to the materials it is very easy to make errors due to

poor adhesion or sudden removal in the tensile testing process

For our second part of the independent study the following can be made

1 At the beginning of this independent study we had no idea what Bose-Einstein Condensate was

or what was its purpose After much literature we finally comprehended the basic principles to

put into practice for our research

2 Our systemrsquos basic working principles and equipmentrsquos complexity are a little difficult to grasp

but hopefully we were able to understand enough of it

3 Theoretically from relation between the power and current we can know the advantages and

disadvantages of AR Coating

4 We were able to assemble the system and run test on its functions Even though we were able to

do this there is still much more work left to do with this system

52 Recommendations

For the Tensile Testing the following can be said

1 Ask the provider to check on the process of heat treatment on the SUM 23 material and give

them the information we have gathered through our test so they can correct for the mechanical

properties found if any change is needed

2 To avoid the problem of the inaccuracy of the poor adhesion of strain gauges we can attach

multiple strain gauges to the same one specimen so as to correlate data and improve our results

For the AR Coating the following can be said

1 We need to make sure that there are no physical defects on the main body of the chamber so as to

achieve maximum efficiency in the vacuum process If there was then the vacuum will arrive to

certain point and then start to decrease

2 It would be preferable to add some sort of visual aid that will allow the user to check the inside of

the chamber without actually opening it This will help us determine at what times we should

manipulate the current to better evaporate the substrate

94

REFERENCES

[1] A L Window Strain Gauge Technology Elsevier Applied Science London and New York 2nd

Edition 1992

[2] CC Perry and HR Lissner Strain Gauge Primer McGraw-Hill Book Co Inc New York 1955

[3] James W Dally William F Riley McGraw-Hill 1978

[4] University of Colorado Boulder BEC - What is it and where did the idea come from

httpwwwcoloradoeduphysics2000becwhat_is_ithtml

[5] Ultraslow Light amp Bose-Einstein Condensates Two-way Control with Coherent Light amp Atom

Fields Harvard Hau Lab Dr Lene Vestergaard Hau Optics amp Photonics News 16 1995

[6] The Art of Taming Light Ultra-slow and Stopped Light Harvard Hau Lab Dr Lene

Vestergaard Hau Europhysics News 2004

[7] Nonlinear Optics Shocking Superfluids Harvard Hau Lab Dr Lene Vestergaard Hau Nature

Physics 2007

[8] Model P3 Strain Indicator and Recorder Instruction Manual Vishay Micro-Measurements 2005

[9] Granville-Phillips Series 375 Convectron Vacuum Gauge Controller Instruction Manual Brooks

Automation 2008

[10] Effect of Film Thickness on the Validity of the Sauerbrey Equation for Hydrated Polyelectrolyte

Films Vogt Lin Wu White 2004

[11] Quartz Crystal Microbalance Study of DNA Immobilization and Hybridization for DNA Sensor

Development Chang Zhao 2008

[12] Installation of Strain Gages with SR-4 PrecoatAdhesive Vishay Micro-Measurements 2005

[13] Strain Gauge Measurement ndash A Tutorial National Instruments 1998

[14] Correlation between Vickers Hardness Number and Yield Stress of Cold-Formed Products

Yavuz Tekkaya

[15] httpsenwikipediaorg

Page 28: PC Hinge Materials Testing and AR Laser Diode Coating

28

233 Laser Diode Basic Principles

A laser diode is a laser whose active medium is a semiconductor similar to that found in

light-emitting diodes (LEDs) Please refer to figure 2-17 The most common type of laser diode is formed

from a p-n junction and powered by injected electric current

Fig 2-17 Laser Diode

Laser diodes are formed by doping a very thin layer on the surface of a crystal wafer The crystal is

doped to produce the n-type region and a p-type region one above the other

By referring to figure 1-2 we can see the basic structure of a working laser When the laser diode has

a current passing through it the light will get excited inside its gain medium and then will start to

resonate this process is called pumping The current exceeds the critical current and then it comes out as

laser light Please refer to figure 1-3 Since we use an external cavity laser we need to apply the AR

coating to the diode and adjust a diffraction grating The laser light comes out the diode and bounces on

the grating making the resonance externally and this becomes the ldquocavityrdquo as shown in figure 2-18

Fig 2-18 Tunable Laser Basic Configuration

29

The most important feature of the external cavity laser is that we can adjust the wavelength easily just

by changing the diffraction gratingrsquos angle and in the end this is the output wavelength of the laser For

different wavelengths there will be different levels of visible light as shown in figure 2-19

Fig 2-19 Light Spectrum

234 Quartz Microbalance System

A Quartz Crystal Microbalance is an instrument that measures a mass per unit area by measuring the

change in frequency of a quartz crystal resonator The resonance is disturbed by the addition or removal

of a small mass due to oxide growthdecay or film deposition (which is the case in our study) at the

surface of the acoustic resonator The QCM can be used under vacuum in gas phase and more recently in

liquid environments It is useful for monitoring the rate of deposition in thin film deposition systems

under vacuum Frequency measurements are easily made with high precision

For our research we used the Sigma Instruments SQM-160 RateThickness Monitor shown in figure

2-20

Fig 2-20 Front and Back Panels of SQM-160

30

The microbalance uses Quartz as the resonator Quartz is one member of the family of crystals that

experience the Piezoelectric Effect

Piezoelectricity is the charge that accumulates in certain solid materials in response to applied

mechanical stress It means electricity resulting from pressure It was discovered in 1880 by Jacques and

Pierre Curie It is understood as the linear electromechanical interaction between the mechanical and the

electrical state in crystalline materials with no inversion symmetry It is a reversible process in that

materials exhibiting direct piezoelectricity also exhibit the reverse This means that the internal generation

of electrical resulting from applied mechanical force and vice versa

By using the piezoelectric effect we can probe as an acoustic resonance by electrical means Applying

alternating current to the quartz crystal induces oscillations This creates a shear wave We can use these

qualities to determine the resonance frequency at high accuracy

The frequency of oscillation of the crystal is partially dependent in the thickness of the crystal During

normal operation all the variables are held constant so a change in thickness correlates directly to a

change in frequency As mass is deposited or etched away the thickness increases or decreases and so the

frequency of oscillation changes accordingly With some simplifying assumptions the frequency change

can be quantified and correlated precisely to the mass change using the Sauerbreyrsquos Equation

Developed by G Sauerbrey in 1959 it is a method for correlating changes in the oscillation

frequency of a piezoelectric crystal with the mass deposited on it It is defined as below

Where f0 is the Resonant frequency Δf is the Frequency change Δm is the mass change A is the

piezoelectrically active area of the crystal q is the Density of quartz (2648 gcmsup3) and μq is the Shear

modulus of quarts(2947x gcmssup2)

Because the film is treated as an extension of thickness Sauerbreyrsquos equation only applies to systems

in which the following 3 conditions are met

Deposited mass must be rigid

Deposited mass must be distributed evenly

The frequency change

lt002

If the change is greater than 2 the Z-match method must be used to determine the change in mass

It is defined as

Where fL is the frequency of the loaded crystal fU is the resonant frequency Nq is the frequency

constant (1668x HzAring) Δm is the mass change A is the piezoelectrically active area of the crystal

31

q is the density of quartz Z is the method constant f is the density of film μq Is the shear modulus of

quarts and μf is the shear modulus of film

The Sauerbrey equation cannot be applied to systems under liquid medium

The crystals are seed crystals plated with gold on both top and bottom for applications A crystal is

shown in figure 2-21 The QCM consists of a thin piezoelectric plate with electrodes evaporated on both

sides Due to the piezoelectric effect AC voltage across the electrodes induces a shear deformation and

vice versa The electromechanical coupling provides a simple way to detect an acoustic resonance by

electrical means

The Z also called Z-factor is a constant value for different materials and it is shown together with the

density of different materials in table 2-2 below

Fig 2-21 QCM Crystals

The Oscillator of the SQM-160 is shown in figure 2-22 and the equivalent circuit for the Resonant

Oscillator is shown in figure 2-23

Fig 2-22 SQM-160 Oscillator

32

Fig 2-23 Oscillator Circuit

33

Table 2-2 Z-Ratios for Different Materials

Table 2-2 Continued

34

Table 2-2 Continued

35

Table 2-2 Continued

36

Table 2-2 Continued

37

Table 2-2 Continued

38

Table 2-2 Continued

235 Vacuum Chamber System

Vacuum Evaporation is the process of depositing thin films of materials onto surfaces The technique

consists of pumping a vacuum chamber to pressures of less than torr and heating a material to

produce a flux of vapor in order to deposit the material onto a surface The material to be vaporized is

typically heated until its vapor pressure is high enough to produce a flux several Angstrom per second by

using an electrically resistive heater or bombardment by a high voltage beam The process was invented

by Henri Nestle in 1886 for food industry

In here the system has been pumped to a vacuum of Torr When a high current is passed

through the filament boat the filament boat is heated over the desired metal evaporation temperature and

so evaporation starts When the evaporation process is finished and the metal cools down crystals

condensate in the surface of the wafer From the weight of the evaporated material the distance between

the filament boat and the wafer we are able to calculate the deposition thickness and we can also use the

mass detector follower like the Quartz crystal resonator microbalance system In the process of

evaporation we usually use a board in between the filament boat and the wafer This is because before we

arrive to the desired evaporation temperature there will be some impurities that will be vaporized in the

controlled environment so we first use a small current and the board in between to get rid of those

impurities and this raises the purity of the deposition material

39

A vacuum evaporation system is shown in figure 2-24

Fig 2-24 Vacuum Evaporation System

Rough Vacuum 760 ~ 1 torr

Medium Vacuum 1 ~ torr

High Vacuum ~ torr

Ultra-High Vacuum Lower than torr

Table 2-3 Classification of Vacuum

For our study we need to use a Turbo Pump A regular turbo pump is shown in figure 2-25

Fig 2-25 Turbo Pump

For our research we used the Pfeiffer TCP 015 Electronic Drive Unit and Granville Phillips 375

Convectron shown below in figure 2-26

40

Fig 2-26 Control and Measurement Equipment

The electronic drive controls the turbo pump and the Convectron measures the pressure inside our

chamber The turbo pump is a type of vacuum pump used to maintain high vacuum Most turbo pumps

are centrifugal When we start the pumping we need to use a mechanical pump so as to decrease the

pressure inside the system from constant atmospheric pressure to torr and then the use dispersion

pump to continue the vacuum until we get to the desired pressure We need to notice though when we

start the dispersion pump we canrsquot turn off the mechanical pump and they both need to run together If

we need to turn off the pumping we first turn off the dispersion pump wait for it to completely stop and

then turn off the mechanical pump

Our completely assembled system is shown in figure 2-27 below

Fig 2-27 Complete System

41

Chapter 3 TENSILE TESTING IN DEPTH

31 Experimentrsquos Purpose and Principles

By means of Universal testing machine and Strain gauges we were able to observe discuss and

analyze the phenomena created when a specimen of certain material is manipulated under an external load

and determine the stress strain and deformation values later we can use the graphing methods of

stress-strain diagram to describe it

The main point of this experiment is that after the tensile specimen is tested use computer analysis

and the actual strain data and after statistical adjustment make the final results report (Tensile testing

experiment is in accordance with ASTM E8)

32 Experimentrsquos Equipment

321 Universal Testing Machine

For the materials testing experiment part of this research we use a Universal Testing Machine as

shown in figure 31 The maximum load it can apply is 100 Ton After the test specimen is secured on the

device with the use of instrumentation the load exerted and the effects of this become apparent on the

specimen and even the smallest of changes can be recorded For our research we used the Chun Yen

Testing Machines Co Ltd 100 Ton Micro Computer Universal Tensile Tester

Fig 31 Universal Testing Machine

42

Table 31 shows the specifications for this machine

Max Capacity 100 Ton

Accuracy plusmn1

Tension (mm) Max Space 1150mm

Grip for Rod 20-70mm

Ram Stroke 250mm

Effective Column Interval 940mm

Crosshead Speed 300mmmin

Testing Speed 0-50mmmin

Volume of Machine 1700times1000times3350mm(LtimesWtimesH)

Volume of Control Panel 1000times800times1500mm(LtimesWtimesH)

Weight 8000kg

Power 3∮220V 20A

Computer AMD K6-2-350

OS Windows XP

Screen 15rdquo CRT

Table 3-1 Chun Yen Testing Machine Specs Table

The connections diagram is shown in figure 3-2

Fig 3-2 Diagram for System Connections

43

When the test specimen is placed when the external force is applied the Load Cell can measure the

size of the applied force and the Encoder measures the expansion rate of change The Local Controller

receives all the information from the 2 units after arranging the results they are displayed in the

computer and they can be afterwards submitted for more complex analysis such as Finite Element

Analysis and we can get the Stress-Strain Diagram

322 Strain Measurement Equipment

The equipment used in our research provides a four-channel measurement that means we can use up

to 4 strain gauges at a time to do our measurements and provides 3 different bridge arrangements as

shown in figure 3-3

(a) (b) (c)

Fig 3-3 Input Connections for Strain Indicator

Figure 3-3 (a) is the Quarter Bridge (b) is the Half Bridge and (c) is the Full Bridge and Transducers

For our study we used the Quarter Bridge and use the Strain Gauge values to decide the position of the

connecting wires The Strain indicator is shown in figure 3-4

Fig 3-4 Vishay Micro-Measurements Model P3 Strain Indicator and Recorder

44

Input Connections Tool Free eccentric lever release

4-channel input

Wire diameter16-28AWG

Bridge Configurations Quarter- Half- and Full Bridge

Bridge Impedance 60-2000Ω

Display 128 64 pixel FSTN positive gray LCD

Data Conversion AD Converter filter

Measurement Range Resolution Strain Range plusmn155mVV

Resolution plusmn00005mVV

Measurement Accuracy plusmn01 of reading plusmn3 counts

Gage Factor Control 0500-9900

Balance Control Software either manual or automatic

Bridge Excitation 15VDC nominal

Communication Interface USB Cable Included

Data Storage Removable Media Card

Shunt Calibration Across bridge completion resistors controlled

by software When Gage Factor=200

120Ω350Ω1000Ω

Analog Output Value 0 to 25V max

Ranges plusmn320 microε plusmn3200 microε plusmn32000 microε

Error 05 output voltage +5mV

Max Error 14 output voltage + 20mV

Update rate 480 samplessec

Output Load 2000Ω

Power Battery Two Alkaline D cells

Battery life 400 hours typ

USB 5V 100mA

Operational Environment Temperature 0-50

Humidity Up to 90 Non-condensing

Case Aluminum Alloy

Size and Weight 228times152times152(mm) 20(kg)

Table 3-2 Vishay Micro-Measurements Model P3 Strain Indicator and Recorder Specs

45

323 Strain Gauge

The strain gaugersquos main basic principle is to use a resistancersquos characteristics to measure the strain

The inside connections of the strain indicator are shown in figure 3-5

Fig 3-5 Inner Connections

As shown above this is a quarter-bridge connection We connect equal-length 3 wires to the 2

connections allowed by the strain gauge wire 1 and 3 can be used to cancel out the effects of temperature

to the resistance and because of the addition of wires 1 and 3 wire 2 can directly measure the experiment

results from the strain gauge and therefore the strain developed with no influence of temperature

If there were no two measuring leads then the relations will be

R 4 =R g +2R L

Where Rg is the Strain Gauge Value and RL is the wire resistance then

4

4

R

R=

Lg

g

RR

R

2

=

gL

gg

RR

RR

21

amp

4

4

R

R=

g

g

R

R(1- L)

Where L is the Signal Loss Factor and so

L =gL

gL

RR

RR

21

2

g

L

R

2R if

g

L

R

2Rltlt1

46

(Actual Value R g =120R L =08g

L

R

2Ris always much smaller than 1)

R 4 =R g +2R LR 2 =R 3 =rR gR 1 =R g 32 RR =0

V 0 =V 2)1( r

r

(

4

4

R

R-

1

1

R

R)

The first term describes loss attenuation effects second term describes loss of balancing capabilities

effects

V 0 =V 2)1( r

r

[

)2

(Lg

g

RR

R

+

T

Lg

g

RR

R

)

2( + T

Lg

L

RR

R

)

2

2( -(

g

g

R

R) T ]

The first term describes loss attenuation effects and loss of balancing capabilities effects the second

third and fourth terms describe the temperature effects on the wire

For the three-wire method we have

L =gL

gL

RR

RR

1

g

L

R

R if

g

L

R

Rltlt1

V 0 =V 2)1( r

r

[

)(Lg

g

RR

R

+

T

Lg

g

RR

R

)( + T

Lg

L

RR

R

)

2( -

T

Lg

g

RR

R

)( - T

Lg

L

RR

R

)

2( ]

V 0 = V2)1( r

r

)(

Lg

g

RR

R

In the last four terms inside parenthesis we can see the effects of temperature being cancelled out and the

effect on first term is not great so this is the reason why in our research we use three wires

47

324 Specimen Measurements

The tensile specimens used in this research are compliant of ASTM E8 Tensile parameters as shown

in figure 3-6

Fig 3-6 Tensile Specimen

Diameter

D(mm)

Gauge

Length

G(mm)

Smallest

Arc

Radius

R(mm)

Shortest

Area

A(mm)

Total

Length

L(mm)

Clamping

Area

Length

B(mm)

Clamping

Area

Diameter

C(mm)

Bar 125 02 625 01 gt10 gt75 ~ 145 ~ 35 20

Table 3-3 Specifications for Round Bar

33 Experiment Procedure

1 Attaching the Strain Gauge to the Tensile Specimen

(1) Prepare 1 ASTM E8 compliant tensile specimen round bar as shown in figure 3-7

(2) Prepare Strain Gauge as those described in table 3-4

(3) Prepare other consumables and adhesive agent such as epoxy adhesive or

cyanoacrylate adhesive as shown in figure 3-8

48

Fig 3-7 Actual Tensile Specimen

Fig 3-8 Other Materials Used (Such as Alcohol gauze transparent tape adhesive)

Gage Type

EA-06-120LZ-120E

Resistance in ohms at 24∘C

1200plusmn03

Gage Factor at 24∘C

2075plusmn05

Transverse Sensitivity at 24∘C

(+07plusmn02)

Table 3-4 Specifications for Strain Gauge

2 Attaching Strain Gauge

As shown in following figures we shall explain the attachment of the strain gauge

(1) Use sand paper and a rasp to clean thoroughly the surface where the strain gauge will be

attached to

49

(a)

(2) Use alcohol to wash the surface where the strain gauge will be attached and use gauze to rub

it off

(b)

(3) Find a clean surface and clean it with alcohol and gauze

(c)

(4) Place the strain gauge in the clean surface Use a piece of transparent tape on top of the strain

gauge after securely placed rip it off the surface carefully

50

(d)

(5) Use a piece of white paper to mark the place where the strain gauge will be attached and in

this way we can make sure that the strain gauge will be placed as horizontally and vertically

correct as possible

(e)

(6) In the place where we had our mark place the strain gauge

(f)

(7) Carefully lift one side of the tape and apply some of the adhesive agent to both the strain

gauge and specimenrsquos surface

(g)

51

(8) We need to make sure that the gauge and the specimen will be firmly attached so we gently

apply pressure with our thumb

(h)

(9) After the adhesive is fully dry we can carefully rip off the tape

(i)

(10) We need to do the whole process twice one for the horizontally placed strain gauge and one

for the vertically placed strain gauge

52

(j)

(11) We now proceed to solder the wires to the strain gauge

(k)

(12) After soldering we use a Volt Multimeter to measure that there is no contact between wires

If there is none then the specimen is ready for testing

(l)

(13) We now need to measure a 5cm distance and mark it to check and compare the elongation

before and after the tensile testing

(m)

53

Fig 3-9 Specimen-Strain Gauge Process

3 Tensile Test

(1) Enter the computer application that controls the tensile testing machine

(2) Turn on the tensile testing machine main switch

(3) Adjust the hydraulic pump to go back to its original position

(4) Bring the lowering motor down to a distance enough so as to attach the tensile specimen to the

system open the clamps and secure the specimen

(a)

(5) Connect all the necessary wires to the strain indicator equipment

54

(b)

(6) Start the ascending motor and wait for the expansion

(c)

Fig 3-10 Specimen-Tensile Testing Process

4 Start the Test

(1) Enter the software application and enter some variables needed for the experiment in the

specific screen

(2) Go back to the main screen and press the [測試] (measure) button to start the test and auto

recording in the software

(3) After the specimen breaks the mechanical device will automatically stop and ask the user to

enter the total displacement We take out the specimen from the testing machine and adjust the

machinersquos position back to its original position

(4) Save the results information

(5) Record the results from the strain indicator

34 Results

From this experiment we can get the Poissonrsquos Ratio Youngrsquos Modulus and Yield Strength etc and

because of the slippage phenomenon in the clamp at the moment of the test then the Elastic Limit will

display some yield phenomena So omit any undesirable results we just take the Yield portion of the

results as reference

In the process of the experiment the most important part to attend to is the attaching of the strain

gauge because the gaugersquos purpose is to measure the strain developed during the test and this strain

might be very small If the gaugersquos angle change during the test ie is not well attached this will affect

the accuracy of the measurements of Poissonrsquos ratio and Youngrsquos modulus

55

The materials provided by the manufacturer are SUM 23 and SUM 43 steel round bars and these two

types of materials have been through different heat treatment processes so they can be sub-divided

further into untreated material heat-treated material and black surface heat treated material for the two

materials with heat treatment the treatment process and finished are different In the end we only have

the mechanical properties that were calculated after our research of these materials

All of the specifications are identical to those shown in figure 3-6

341 SUM 23

Fig 3-11 SUM 23 Untreated Material

Number 7 10

Hardness(HRB) 74 75

Yield Stress (MPa) 448 440

Tensile Strength (MPa) 544 560

Poissonrsquos Ratio 029 027

Youngrsquos Modulus (GPa) 203 210

Cut-off Area Shrinking () 42 41

Elongation () 1125 1011

Table 3-5 Mechanical Properties of SUM 23 Untreated

56

Stress-Strain Diagram

(a)

(b)

57

Fig 3-12 Stress-Strain Diagrams for (a) 7 Round Bar and (b) 10 Round Bar

Cut-Off Area

(a)

(b)

Fig 3-13 Cut-Off Area of (a) 7 Round Bar and (b) 10 Round Bar

58

SUM 23 Nickel Round Bar

Fig 3-14 SUM 23 Nickel Material

Number 1 2 3 4

Hardness(HRB) 48 50 49 48

Yield Stress (MPa) 370 370 380 400

Tensile Strength (MPa) 455 451 450 450

Poissonrsquos Ratio 028 046 029 026

Youngrsquos Modulus (GPa) 243 303 246 206

Cut-off Area Shrinking () 803 803 726 601

Elongation () 566 65 602 647

Table 3-6 Mechanical Properties of SUM 23 Nickel

59

Stress-Strain Diagram

(a)

60

(b)

(c)

(d)

61

Fig 3-15 Stress-Strain Diagrams for (a) 1 Round Bar (b) 2 Round Bar (c) 3 Round Bar and (d)

4 Round Bar

Cut-Off Area

(a)

(b)

62

(c)

(d)

Fig 3-16 Cut-Off Area of (a) 1 Round Bar (b) 2 Round Bar (c) 3 Round Bar and (d) 4 Round

Bar

63

SUM 23 Black Surface Round Bar

Fig 3-17 SUM 23 Black Surface Material

Number 1 2 3

Hardness(HRB) 51 50 51

Yield Stress (MPa) 378 371 369

Tensile Strength (MPa) 467 465 464

Poissonrsquos Ratio 03 016 04

Youngrsquos Modulus (GPa) 215 266 266

Cut-off Area Shrinking () 986 94 848

Elongation () 748 805 761

Table 3-7 Mechanical Properties of SUM 23 Black Surface Material

64

Stress-Strain Diagram

(a)

(b)

65

(c)

Fig 3-18 Stress-Strain Diagrams for (a) 1 Round Bar 2 Round Bar and (c) 3 Round Bar

Cut-Off Surface

(a)

66

(b)

(c)

Fig 3-19 Cut-Off Surface of (a) 1 Round Bar 2 Round Bar and (c) 3 Round Bar

67

342 SUM 43

Fig 3-20 Untreated SUM 43 Untreated Material

Number 1 5

Hardness(HRB) 76 75

Yield Stress (MPa) 572 594

Tensile Strength (MPa) 743 785

Poissonrsquos Ratio 027 029

Youngrsquos Modulus (GPa) 200 202

Cut-off Area Shrinking () 338 2944

Elongation () 857 894

Table 3-8 Mechanical Properties of SUM 43 Untreated

68

Stress-Strain Diagrams

(a)

(b)

Fig 3-21 Stress-Strain Diagrams for SUM 43 (a) 1 Round Bar and (b) 5 Round Bar

69

Cut-Off Area

(a)

(b)

Fig 3-22 Cut-Off Area of SUM 43 (a) 1 Round Bar and (b) 5 Round Bar

70

SUM 43 Nickel Round Bar

Fig 3-23 SUM 43 Nickel Material

Number 4 5

Hardness(HRB) 51 50

Yield Stress (MPa) 1580 1544

Tensile Strength (MPa) 1639 1625

Poissonrsquos Ratio 03 028

Youngrsquos Modulus (GPa) 194 201

Cut-off Area Shrinking () 1697 137

Elongation () 376 265

Table 3-9 Mechanical Properties of SUM 43 Nickel

71

Stress-Strain Diagrams

(a)

(b)

Fig 3-24 Stress-Strain Diagrams for (a) 4 Round Bar and (b) 5 Round Bar

72

Cut-Off Area

(a)

(b)

Fig 3-25 Cut-Off Area of (a) 4 Round Bar and (b) 5 Round Bar

73

SUM 43 Black Surface Material

Fig 3-26 SUM 43 Black Surface Material

Number 3 5

Hardness(HRB) 56 56

Yield Stress (MPa) 1416 1361

Tensile Strength (MPa) 1591 1402

Poissonrsquos Ratio 029 031

Youngrsquos Modulus (GPa) 200 202

Cut-off Area Shrinking () 139 124

Elongation () 24 24

Table 3-10 Mechanical Properties of SUM 43 Black Surface Material

74

Stress-Strain Diagrams

0 2 4 6 8 10 12 14

-200

0

200

400

600

800

1000

1200

1400

1600

1800

應力 (MPa)

應變()

(a)

0 2 4 6 8 10

-200

0

200

400

600

800

1000

1200

1400

1600

應力

(MPa)

位移 ()

(b)

Fig 3-27 Stress-Strain Diagrams for (a) 3 Round Bar and (b) 5 Round Bar

(Note These curves were formulated using Visual Solutions Inc VisSim Software)

75

Cut-Off Area

(a)

(b)

Fig 3-28 Cut-Off Area of (a) 3 Round Bar and (b) 5 Round Bar

76

The force value (N) was retrieved from the Universal Testing Machine

The Poissonrsquos Ratio (ε) is calculated as

ε =

the values for the Poissonrsquos Ratio are in average around 0297

The Youngrsquos Modulus (E) is calculated as

E =

Where

Stress =

Cross-sectional Area =

where D is the Diameter

The value for D was in average around 1258 mm

The values shown by the computer because there is Slippage phenomena between the Clamp and the

specimen will not be taken into consideration for the elongation strain and Youngrsquos modulus and we will

refer to the values that we have meticulously calculated

77

Chapter 4 AR COATING IN DEPTH

41 Experimentrsquos Purpose and Principles

By means of a vacuum chamber and several other instruments we intend to apply Anti-Reflective

Coating using deposition process to a laser diode and in this way reduce its refraction so as to make it

lose less light in the process of amplification and we can control certain wavelengths we want produced

for certain desired applications in our case we are attempting to re-create a Bose-Einstein Condensate

An optimal BEC apparatus is shown in figure 4-1

Fig 4-1 BEC Apparatus

The main point of this experiment is to build a vacuum chamber system attach all the instrumentation

needed (Vacuum pump deposition meter and voltmeter) and use it to apply AR coating to a laser diode

After we have accomplished the AR coating other team will be in charge of designing the BEC apparatus

and use the results of our research

78

42 Experimentrsquos Equipment

421 Vacuum Chamber

For this research we designed a vacuum chamber whose main body is shown in figure 4-2 Its

dimensions are

Width 240 mm

Length 240 mm

Height 200 mm

Outer Diameter 4 in

Inner Diameter 15 in

Fig 4-2 Vacuum Chamber Main Body

The chamber is made up of 6 pass ways pass way A is the connection with the Laser Deposition

Equipment pass way B is the connection with the Turbo Pump and pass way C is for the connection with

the Deposition Source

A

C

B

79

Pass way C is for the deposition source as mentioned above This is a system where a thermal

resistance is heated by passing a high current through it which heats up a filament boat (made of tungsten)

where the material to be evaporated is place We control the temperature as such that the material will

evaporate and the heat will not cause the filament boat to crack

Because P = Isup2 R (where P is power I is current and R is resistance) to avoid the current to flow

where it is not desired we decided that the material for the Thermocouple shown in figure 4-3 should be

Copper ᴓ 63 mm We choose it that way because Copper has very good heat dissipation characteristics

and the resistance value is low It can reduce the value of the current enough to make the thermocouple to

create heat

Fig 4-3 Thermocouple

To the thermocouple we attach the tungsten filament boat We need to take notice of materials to be

used in this design because when using high current the tungsten filament boar will heat up and so the

material must be able to keep up with the heating potential of tungsten and has a low coefficient of heat

dissipation to avoid the tungsten to fail when heating up and therefore not evaporating Considering all

this we decide to use Stainless Steel

Because this clamp will be assembled inside the chamber after many revisions it was determined it

will have the shape shown in figure 4-4

Fig 4-4 Filament Boat Clamp Design

80

For the tungsten filament boat we bought the product from a distributor The dimensions are

Length 100 mm

Width 10 mm

Height 1 mm

Our thermocouple is 15 in but the pass way C is 4 in so we need to attach a Flange that connects

15in to 4in Because these specifications are quite difficult to achieve by Milling we had to use

electrical wire cutting

For the laser clamping system where the laser that is going to be AR coated will be placed will be

connected to pass way A the assembly is shown in figure 4-5 below

Fig 4-5 Cover Assembly

For this design we used an O-ring instead of a gasket so as to save time The design of the assembly

where the laser will be placed is shown in figure 4-6

Fig 4-6 Upper Cover Inner Assembly

D

E

F

81

Point D is the plate in the assembly where the laser diode will be fixed Because of the easy

processing we decide to use Aluminum and it is screwed to the top cover Point E is the connection for

the Quartz crystal resonator and it is designed in the same as point F in this way the results of the quartz

microbalance system will be more accurate in real time Point F is the final resting place for the laser

diode We use a Thor Labs Base with dimensions of ᴓ 9mm and ᴓ 56mm for two different size laser

diodes It just needs to be plugged in for easy installation

From figure 4-6 we know that the system needs signal system connections and because of the

change in temperature inside the chamber this could affect the functioning of the quartz microbalance so

we also need to install water tubes for cooling This is shown in figure 4-7 below

Fig 4-7 Diagram of Upper Cover Connections

In figure 4-8 we show the Feed through connections and their functions

Fig 4-8 Feed through Diagram

82

1 SQM-160 wire 5 Laser Connection 1 (Vin)

2 SQM-160 (G) 6 Laser Connection 2 (G)

3 K-Type-1 7 Laser Connection 3 (PD)

4 K-Type-2 8 Not In Use

The fully assembled chamber is shown in figure 4-9

Fig 4-9 Fully Assembled Chamber

422 Quartz Crystal Microbalance

For measuring the deposition on our target for coating we used the Inficon SQM-160 RateThickness

Monitor It is an easy to use instrument for measuring many types of thin-film coatings as shown in

figure 4-10

(a) Front Panel (b) Back Panel

Fig 4-10 Inficon SQM-160

83

Table 4-1 shows the technical specifications for this equipment

Number of sensors 2 Standard 4 additional optional

Sensor Frequency Range 40 MHz ~ 60 MHz

Reference Frequency Accuracy 002

Thickness Display Resolution 1 Aring

Thickness Resolution 015 Aring (Std) 0037 Aring (Hi Res)

Density of Stored Films 05-9999 gmcc

Tooling 10-399

Z-Factor 010-1000

Final Thickness 0000-9999k Aring

Measurement Period 15 to 2 sec

Simulation Mode Yes

Frequency Mode Yes

Rate Resolution 011 Arings

Dual Crystal Yes

Etch Mode Yes

Crystal Tooling 10-399

Crystal Fail Min Max 40 to 60 MHz 41 to 61 MHz

Power 100-120 200-240~plusmn10 nominal 20W

Operation Environment 0degC ~ 50degC

0 ~ 80 RH non-condensing

0 ~ 2000 meters

Class 1 Equipment

Pollution Degree 2

Rack Dimensions 885mm x 2127mm x 1969mm

Weight 27 kg

Table 4-1 Inficon SQM-160 RateThickness Monitor Specs

84

To the SQM-160 we need to connect an Oscillator We use the Sigma Instruments Remote Oscillator

Ser No 2 268 as shown in figure 4-11

Fig 4-11 Sigma Instruments Remote Oscillator

The connections diagram is shown in figure 4-12

Fig 4-12 SQM-160 Connections Diagram

85

423 Turbo Pump

For our experiments we used the Pfeiffer TCP 015 Electronic Drive Unit shown below in figure 4-13

Table 4-2 shows the technical specifications for this equipment

(a) Front Panel (b) Back Panel

Fig 4-13 Pfeiffer TCP 015 Electronic Drive

Connection Voltage (100V) 90-112

Mains Frequency 5060 Hz

Start-up Current 22 A

Nominal Frequency 1500 Hz

Rotation Speed 10V = 1500Hz plusmn2

Analog Output Current 10 V = 25 A plusmn 5

Rotation Speed Switchpoint 750 Hz

Works Setting 8 min

Permissible Ambient Temperature 0degC ~ 40degC

Dimensions Front Panel 1285mm x 1063mm

Insertion Length 227mm

Weight 27 Kg

Table 4-2 Pfeiffer TCP 015 Electronic Drive Specs

86

The connections diagram is shown in figure 4-14

Fig 4-14Connections Diagram for Pfeiffer TCP 015

To measure the pressure inside the chamber we use the Granville Phillips 375 Convectron Vacuum

Pressure Controller shown in figure 4-15

(a) Front Panel (b) Back Panel

Fig 4-15 Granville Phillips 375 Convectron

87

Its dimensions are shown in figure 4-16

Fig 4-16 Dimensions of Convectron

Table 4-3 shows the technical specifications for this equipment

Table 4-3 Granville Phillips 375 Convectron Vacuum Pressure Controller Specs

88

424 Multimeter

For our experiment we used the Keithley 2000 Digital Multimeter as shown in figure 4-17

(a) Front Panel (b) Back Panel

Fig 4-17 Keithley Model 2000 6-12-Digit Digital Multimeter

Its technical specifications are shown in table 4-4

Table 4-4 Keithley Model 2000 6-12-Digit Digital Multimeter Specs

89

43 Experiment Procedure

1 Connecting together the equipment and the chamber

(1) We first connect the resonator to the thickness monitor and connect the other side to the

chamber

(2) We now connect the flexible tubes to the turbo pump on one side and to the chamber on the

other

(3) We need to check that tubes are tightly connected to avoid any leaks in the vacuum pumping

process which will not allow us to get to our goal of Torr As shown in figure 4-18

(4) Connect the convectron to the system as shown in figure 4-19

Fig 4-18 checking for leaks using alcohol

Fig 4-19 Convectron attached to System

90

(5) Attach the clamps of the Multimeter to the bottom of the chamber as shown in figure 4-20

(6) Place the Quartz crystal in place

(7) Close tight vacuum chamber

(8) Connect all electrical appliances to power source

Fig 4-20 Multimeter Connections

2 Starting up the System

(1) We turn on all the devices as such Check all systems are ready to function Reset all values

that might be left over from previous tests

(2) Start the thickness monitor and set all values for this experiment In our case we got to testing

the system but not actual coating So we used the simulation mode of the thickness monitor as

shown in figure 4-21

Fig 4-21 Simulation Mode

91

(3) Start the turbo pump Make sure the lid on the vacuum chamber is tightly closed

(4) Start convectron and record initial pressure

(5) Start Multimeter and record initial current

3 Coating Process

(1) If we have the deposition material inside the filament boat the power source for the high

current must be started as well

(2) Record all initial values for thickness current pressure

(3) For an ideal experiment we need a thickness of around 101 nm a pressure of Torr and

a current of 300 A

44 Results

From previous experiments we have shown that we can turn a LED into a laser by means of AR

Coating In figure 4-22 shown below we can compare the actual results of a Diode before and after AR

coating From the blue line we can see that when the diode is at a current of 15mA its light will change

from LED to laser and if we look at the red line its critical current is around 30 to 35 mA

Fig 4-22 AR Coating Comparison for Laser Diodes

This means that the light emitted is not as strong as if the diode had been coated because inside the

chamber there must be some excitation first so the reflectivity of both sides inside the diode must be high

So because of the coating in one of the sides we have opened a door and let the light come out so the

critical current is risen as such and will be higher value than that of before the coating

92

In the following figures we can see the difference between before and after coating in a material The

thickness is around 1016 nm for this material

Fig 4-23 Before Coating

Fig 4-24 After Coating

93

Chapter 5 CONCLUSIONS AND RECOMMENDATIONS

51 Conclusions

For the first part of this independent study taking into consideration the data that came out of our

research and that sent by the provider we can say

1 SUM 23 after heat treatment will unexpectedly develop cracking in the middle of the tensile

testing process and suddenly break

2 Itrsquos possible that in the process of heat treatment to the SUM 23 material the treatment was not

uniform and this will create a pre-loaded moment force on one side that pushes on the other side

of the specimen resulting in material deformation

3 In the process of attaching the strain gauges to the materials it is very easy to make errors due to

poor adhesion or sudden removal in the tensile testing process

For our second part of the independent study the following can be made

1 At the beginning of this independent study we had no idea what Bose-Einstein Condensate was

or what was its purpose After much literature we finally comprehended the basic principles to

put into practice for our research

2 Our systemrsquos basic working principles and equipmentrsquos complexity are a little difficult to grasp

but hopefully we were able to understand enough of it

3 Theoretically from relation between the power and current we can know the advantages and

disadvantages of AR Coating

4 We were able to assemble the system and run test on its functions Even though we were able to

do this there is still much more work left to do with this system

52 Recommendations

For the Tensile Testing the following can be said

1 Ask the provider to check on the process of heat treatment on the SUM 23 material and give

them the information we have gathered through our test so they can correct for the mechanical

properties found if any change is needed

2 To avoid the problem of the inaccuracy of the poor adhesion of strain gauges we can attach

multiple strain gauges to the same one specimen so as to correlate data and improve our results

For the AR Coating the following can be said

1 We need to make sure that there are no physical defects on the main body of the chamber so as to

achieve maximum efficiency in the vacuum process If there was then the vacuum will arrive to

certain point and then start to decrease

2 It would be preferable to add some sort of visual aid that will allow the user to check the inside of

the chamber without actually opening it This will help us determine at what times we should

manipulate the current to better evaporate the substrate

94

REFERENCES

[1] A L Window Strain Gauge Technology Elsevier Applied Science London and New York 2nd

Edition 1992

[2] CC Perry and HR Lissner Strain Gauge Primer McGraw-Hill Book Co Inc New York 1955

[3] James W Dally William F Riley McGraw-Hill 1978

[4] University of Colorado Boulder BEC - What is it and where did the idea come from

httpwwwcoloradoeduphysics2000becwhat_is_ithtml

[5] Ultraslow Light amp Bose-Einstein Condensates Two-way Control with Coherent Light amp Atom

Fields Harvard Hau Lab Dr Lene Vestergaard Hau Optics amp Photonics News 16 1995

[6] The Art of Taming Light Ultra-slow and Stopped Light Harvard Hau Lab Dr Lene

Vestergaard Hau Europhysics News 2004

[7] Nonlinear Optics Shocking Superfluids Harvard Hau Lab Dr Lene Vestergaard Hau Nature

Physics 2007

[8] Model P3 Strain Indicator and Recorder Instruction Manual Vishay Micro-Measurements 2005

[9] Granville-Phillips Series 375 Convectron Vacuum Gauge Controller Instruction Manual Brooks

Automation 2008

[10] Effect of Film Thickness on the Validity of the Sauerbrey Equation for Hydrated Polyelectrolyte

Films Vogt Lin Wu White 2004

[11] Quartz Crystal Microbalance Study of DNA Immobilization and Hybridization for DNA Sensor

Development Chang Zhao 2008

[12] Installation of Strain Gages with SR-4 PrecoatAdhesive Vishay Micro-Measurements 2005

[13] Strain Gauge Measurement ndash A Tutorial National Instruments 1998

[14] Correlation between Vickers Hardness Number and Yield Stress of Cold-Formed Products

Yavuz Tekkaya

[15] httpsenwikipediaorg

Page 29: PC Hinge Materials Testing and AR Laser Diode Coating

29

The most important feature of the external cavity laser is that we can adjust the wavelength easily just

by changing the diffraction gratingrsquos angle and in the end this is the output wavelength of the laser For

different wavelengths there will be different levels of visible light as shown in figure 2-19

Fig 2-19 Light Spectrum

234 Quartz Microbalance System

A Quartz Crystal Microbalance is an instrument that measures a mass per unit area by measuring the

change in frequency of a quartz crystal resonator The resonance is disturbed by the addition or removal

of a small mass due to oxide growthdecay or film deposition (which is the case in our study) at the

surface of the acoustic resonator The QCM can be used under vacuum in gas phase and more recently in

liquid environments It is useful for monitoring the rate of deposition in thin film deposition systems

under vacuum Frequency measurements are easily made with high precision

For our research we used the Sigma Instruments SQM-160 RateThickness Monitor shown in figure

2-20

Fig 2-20 Front and Back Panels of SQM-160

30

The microbalance uses Quartz as the resonator Quartz is one member of the family of crystals that

experience the Piezoelectric Effect

Piezoelectricity is the charge that accumulates in certain solid materials in response to applied

mechanical stress It means electricity resulting from pressure It was discovered in 1880 by Jacques and

Pierre Curie It is understood as the linear electromechanical interaction between the mechanical and the

electrical state in crystalline materials with no inversion symmetry It is a reversible process in that

materials exhibiting direct piezoelectricity also exhibit the reverse This means that the internal generation

of electrical resulting from applied mechanical force and vice versa

By using the piezoelectric effect we can probe as an acoustic resonance by electrical means Applying

alternating current to the quartz crystal induces oscillations This creates a shear wave We can use these

qualities to determine the resonance frequency at high accuracy

The frequency of oscillation of the crystal is partially dependent in the thickness of the crystal During

normal operation all the variables are held constant so a change in thickness correlates directly to a

change in frequency As mass is deposited or etched away the thickness increases or decreases and so the

frequency of oscillation changes accordingly With some simplifying assumptions the frequency change

can be quantified and correlated precisely to the mass change using the Sauerbreyrsquos Equation

Developed by G Sauerbrey in 1959 it is a method for correlating changes in the oscillation

frequency of a piezoelectric crystal with the mass deposited on it It is defined as below

Where f0 is the Resonant frequency Δf is the Frequency change Δm is the mass change A is the

piezoelectrically active area of the crystal q is the Density of quartz (2648 gcmsup3) and μq is the Shear

modulus of quarts(2947x gcmssup2)

Because the film is treated as an extension of thickness Sauerbreyrsquos equation only applies to systems

in which the following 3 conditions are met

Deposited mass must be rigid

Deposited mass must be distributed evenly

The frequency change

lt002

If the change is greater than 2 the Z-match method must be used to determine the change in mass

It is defined as

Where fL is the frequency of the loaded crystal fU is the resonant frequency Nq is the frequency

constant (1668x HzAring) Δm is the mass change A is the piezoelectrically active area of the crystal

31

q is the density of quartz Z is the method constant f is the density of film μq Is the shear modulus of

quarts and μf is the shear modulus of film

The Sauerbrey equation cannot be applied to systems under liquid medium

The crystals are seed crystals plated with gold on both top and bottom for applications A crystal is

shown in figure 2-21 The QCM consists of a thin piezoelectric plate with electrodes evaporated on both

sides Due to the piezoelectric effect AC voltage across the electrodes induces a shear deformation and

vice versa The electromechanical coupling provides a simple way to detect an acoustic resonance by

electrical means

The Z also called Z-factor is a constant value for different materials and it is shown together with the

density of different materials in table 2-2 below

Fig 2-21 QCM Crystals

The Oscillator of the SQM-160 is shown in figure 2-22 and the equivalent circuit for the Resonant

Oscillator is shown in figure 2-23

Fig 2-22 SQM-160 Oscillator

32

Fig 2-23 Oscillator Circuit

33

Table 2-2 Z-Ratios for Different Materials

Table 2-2 Continued

34

Table 2-2 Continued

35

Table 2-2 Continued

36

Table 2-2 Continued

37

Table 2-2 Continued

38

Table 2-2 Continued

235 Vacuum Chamber System

Vacuum Evaporation is the process of depositing thin films of materials onto surfaces The technique

consists of pumping a vacuum chamber to pressures of less than torr and heating a material to

produce a flux of vapor in order to deposit the material onto a surface The material to be vaporized is

typically heated until its vapor pressure is high enough to produce a flux several Angstrom per second by

using an electrically resistive heater or bombardment by a high voltage beam The process was invented

by Henri Nestle in 1886 for food industry

In here the system has been pumped to a vacuum of Torr When a high current is passed

through the filament boat the filament boat is heated over the desired metal evaporation temperature and

so evaporation starts When the evaporation process is finished and the metal cools down crystals

condensate in the surface of the wafer From the weight of the evaporated material the distance between

the filament boat and the wafer we are able to calculate the deposition thickness and we can also use the

mass detector follower like the Quartz crystal resonator microbalance system In the process of

evaporation we usually use a board in between the filament boat and the wafer This is because before we

arrive to the desired evaporation temperature there will be some impurities that will be vaporized in the

controlled environment so we first use a small current and the board in between to get rid of those

impurities and this raises the purity of the deposition material

39

A vacuum evaporation system is shown in figure 2-24

Fig 2-24 Vacuum Evaporation System

Rough Vacuum 760 ~ 1 torr

Medium Vacuum 1 ~ torr

High Vacuum ~ torr

Ultra-High Vacuum Lower than torr

Table 2-3 Classification of Vacuum

For our study we need to use a Turbo Pump A regular turbo pump is shown in figure 2-25

Fig 2-25 Turbo Pump

For our research we used the Pfeiffer TCP 015 Electronic Drive Unit and Granville Phillips 375

Convectron shown below in figure 2-26

40

Fig 2-26 Control and Measurement Equipment

The electronic drive controls the turbo pump and the Convectron measures the pressure inside our

chamber The turbo pump is a type of vacuum pump used to maintain high vacuum Most turbo pumps

are centrifugal When we start the pumping we need to use a mechanical pump so as to decrease the

pressure inside the system from constant atmospheric pressure to torr and then the use dispersion

pump to continue the vacuum until we get to the desired pressure We need to notice though when we

start the dispersion pump we canrsquot turn off the mechanical pump and they both need to run together If

we need to turn off the pumping we first turn off the dispersion pump wait for it to completely stop and

then turn off the mechanical pump

Our completely assembled system is shown in figure 2-27 below

Fig 2-27 Complete System

41

Chapter 3 TENSILE TESTING IN DEPTH

31 Experimentrsquos Purpose and Principles

By means of Universal testing machine and Strain gauges we were able to observe discuss and

analyze the phenomena created when a specimen of certain material is manipulated under an external load

and determine the stress strain and deformation values later we can use the graphing methods of

stress-strain diagram to describe it

The main point of this experiment is that after the tensile specimen is tested use computer analysis

and the actual strain data and after statistical adjustment make the final results report (Tensile testing

experiment is in accordance with ASTM E8)

32 Experimentrsquos Equipment

321 Universal Testing Machine

For the materials testing experiment part of this research we use a Universal Testing Machine as

shown in figure 31 The maximum load it can apply is 100 Ton After the test specimen is secured on the

device with the use of instrumentation the load exerted and the effects of this become apparent on the

specimen and even the smallest of changes can be recorded For our research we used the Chun Yen

Testing Machines Co Ltd 100 Ton Micro Computer Universal Tensile Tester

Fig 31 Universal Testing Machine

42

Table 31 shows the specifications for this machine

Max Capacity 100 Ton

Accuracy plusmn1

Tension (mm) Max Space 1150mm

Grip for Rod 20-70mm

Ram Stroke 250mm

Effective Column Interval 940mm

Crosshead Speed 300mmmin

Testing Speed 0-50mmmin

Volume of Machine 1700times1000times3350mm(LtimesWtimesH)

Volume of Control Panel 1000times800times1500mm(LtimesWtimesH)

Weight 8000kg

Power 3∮220V 20A

Computer AMD K6-2-350

OS Windows XP

Screen 15rdquo CRT

Table 3-1 Chun Yen Testing Machine Specs Table

The connections diagram is shown in figure 3-2

Fig 3-2 Diagram for System Connections

43

When the test specimen is placed when the external force is applied the Load Cell can measure the

size of the applied force and the Encoder measures the expansion rate of change The Local Controller

receives all the information from the 2 units after arranging the results they are displayed in the

computer and they can be afterwards submitted for more complex analysis such as Finite Element

Analysis and we can get the Stress-Strain Diagram

322 Strain Measurement Equipment

The equipment used in our research provides a four-channel measurement that means we can use up

to 4 strain gauges at a time to do our measurements and provides 3 different bridge arrangements as

shown in figure 3-3

(a) (b) (c)

Fig 3-3 Input Connections for Strain Indicator

Figure 3-3 (a) is the Quarter Bridge (b) is the Half Bridge and (c) is the Full Bridge and Transducers

For our study we used the Quarter Bridge and use the Strain Gauge values to decide the position of the

connecting wires The Strain indicator is shown in figure 3-4

Fig 3-4 Vishay Micro-Measurements Model P3 Strain Indicator and Recorder

44

Input Connections Tool Free eccentric lever release

4-channel input

Wire diameter16-28AWG

Bridge Configurations Quarter- Half- and Full Bridge

Bridge Impedance 60-2000Ω

Display 128 64 pixel FSTN positive gray LCD

Data Conversion AD Converter filter

Measurement Range Resolution Strain Range plusmn155mVV

Resolution plusmn00005mVV

Measurement Accuracy plusmn01 of reading plusmn3 counts

Gage Factor Control 0500-9900

Balance Control Software either manual or automatic

Bridge Excitation 15VDC nominal

Communication Interface USB Cable Included

Data Storage Removable Media Card

Shunt Calibration Across bridge completion resistors controlled

by software When Gage Factor=200

120Ω350Ω1000Ω

Analog Output Value 0 to 25V max

Ranges plusmn320 microε plusmn3200 microε plusmn32000 microε

Error 05 output voltage +5mV

Max Error 14 output voltage + 20mV

Update rate 480 samplessec

Output Load 2000Ω

Power Battery Two Alkaline D cells

Battery life 400 hours typ

USB 5V 100mA

Operational Environment Temperature 0-50

Humidity Up to 90 Non-condensing

Case Aluminum Alloy

Size and Weight 228times152times152(mm) 20(kg)

Table 3-2 Vishay Micro-Measurements Model P3 Strain Indicator and Recorder Specs

45

323 Strain Gauge

The strain gaugersquos main basic principle is to use a resistancersquos characteristics to measure the strain

The inside connections of the strain indicator are shown in figure 3-5

Fig 3-5 Inner Connections

As shown above this is a quarter-bridge connection We connect equal-length 3 wires to the 2

connections allowed by the strain gauge wire 1 and 3 can be used to cancel out the effects of temperature

to the resistance and because of the addition of wires 1 and 3 wire 2 can directly measure the experiment

results from the strain gauge and therefore the strain developed with no influence of temperature

If there were no two measuring leads then the relations will be

R 4 =R g +2R L

Where Rg is the Strain Gauge Value and RL is the wire resistance then

4

4

R

R=

Lg

g

RR

R

2

=

gL

gg

RR

RR

21

amp

4

4

R

R=

g

g

R

R(1- L)

Where L is the Signal Loss Factor and so

L =gL

gL

RR

RR

21

2

g

L

R

2R if

g

L

R

2Rltlt1

46

(Actual Value R g =120R L =08g

L

R

2Ris always much smaller than 1)

R 4 =R g +2R LR 2 =R 3 =rR gR 1 =R g 32 RR =0

V 0 =V 2)1( r

r

(

4

4

R

R-

1

1

R

R)

The first term describes loss attenuation effects second term describes loss of balancing capabilities

effects

V 0 =V 2)1( r

r

[

)2

(Lg

g

RR

R

+

T

Lg

g

RR

R

)

2( + T

Lg

L

RR

R

)

2

2( -(

g

g

R

R) T ]

The first term describes loss attenuation effects and loss of balancing capabilities effects the second

third and fourth terms describe the temperature effects on the wire

For the three-wire method we have

L =gL

gL

RR

RR

1

g

L

R

R if

g

L

R

Rltlt1

V 0 =V 2)1( r

r

[

)(Lg

g

RR

R

+

T

Lg

g

RR

R

)( + T

Lg

L

RR

R

)

2( -

T

Lg

g

RR

R

)( - T

Lg

L

RR

R

)

2( ]

V 0 = V2)1( r

r

)(

Lg

g

RR

R

In the last four terms inside parenthesis we can see the effects of temperature being cancelled out and the

effect on first term is not great so this is the reason why in our research we use three wires

47

324 Specimen Measurements

The tensile specimens used in this research are compliant of ASTM E8 Tensile parameters as shown

in figure 3-6

Fig 3-6 Tensile Specimen

Diameter

D(mm)

Gauge

Length

G(mm)

Smallest

Arc

Radius

R(mm)

Shortest

Area

A(mm)

Total

Length

L(mm)

Clamping

Area

Length

B(mm)

Clamping

Area

Diameter

C(mm)

Bar 125 02 625 01 gt10 gt75 ~ 145 ~ 35 20

Table 3-3 Specifications for Round Bar

33 Experiment Procedure

1 Attaching the Strain Gauge to the Tensile Specimen

(1) Prepare 1 ASTM E8 compliant tensile specimen round bar as shown in figure 3-7

(2) Prepare Strain Gauge as those described in table 3-4

(3) Prepare other consumables and adhesive agent such as epoxy adhesive or

cyanoacrylate adhesive as shown in figure 3-8

48

Fig 3-7 Actual Tensile Specimen

Fig 3-8 Other Materials Used (Such as Alcohol gauze transparent tape adhesive)

Gage Type

EA-06-120LZ-120E

Resistance in ohms at 24∘C

1200plusmn03

Gage Factor at 24∘C

2075plusmn05

Transverse Sensitivity at 24∘C

(+07plusmn02)

Table 3-4 Specifications for Strain Gauge

2 Attaching Strain Gauge

As shown in following figures we shall explain the attachment of the strain gauge

(1) Use sand paper and a rasp to clean thoroughly the surface where the strain gauge will be

attached to

49

(a)

(2) Use alcohol to wash the surface where the strain gauge will be attached and use gauze to rub

it off

(b)

(3) Find a clean surface and clean it with alcohol and gauze

(c)

(4) Place the strain gauge in the clean surface Use a piece of transparent tape on top of the strain

gauge after securely placed rip it off the surface carefully

50

(d)

(5) Use a piece of white paper to mark the place where the strain gauge will be attached and in

this way we can make sure that the strain gauge will be placed as horizontally and vertically

correct as possible

(e)

(6) In the place where we had our mark place the strain gauge

(f)

(7) Carefully lift one side of the tape and apply some of the adhesive agent to both the strain

gauge and specimenrsquos surface

(g)

51

(8) We need to make sure that the gauge and the specimen will be firmly attached so we gently

apply pressure with our thumb

(h)

(9) After the adhesive is fully dry we can carefully rip off the tape

(i)

(10) We need to do the whole process twice one for the horizontally placed strain gauge and one

for the vertically placed strain gauge

52

(j)

(11) We now proceed to solder the wires to the strain gauge

(k)

(12) After soldering we use a Volt Multimeter to measure that there is no contact between wires

If there is none then the specimen is ready for testing

(l)

(13) We now need to measure a 5cm distance and mark it to check and compare the elongation

before and after the tensile testing

(m)

53

Fig 3-9 Specimen-Strain Gauge Process

3 Tensile Test

(1) Enter the computer application that controls the tensile testing machine

(2) Turn on the tensile testing machine main switch

(3) Adjust the hydraulic pump to go back to its original position

(4) Bring the lowering motor down to a distance enough so as to attach the tensile specimen to the

system open the clamps and secure the specimen

(a)

(5) Connect all the necessary wires to the strain indicator equipment

54

(b)

(6) Start the ascending motor and wait for the expansion

(c)

Fig 3-10 Specimen-Tensile Testing Process

4 Start the Test

(1) Enter the software application and enter some variables needed for the experiment in the

specific screen

(2) Go back to the main screen and press the [測試] (measure) button to start the test and auto

recording in the software

(3) After the specimen breaks the mechanical device will automatically stop and ask the user to

enter the total displacement We take out the specimen from the testing machine and adjust the

machinersquos position back to its original position

(4) Save the results information

(5) Record the results from the strain indicator

34 Results

From this experiment we can get the Poissonrsquos Ratio Youngrsquos Modulus and Yield Strength etc and

because of the slippage phenomenon in the clamp at the moment of the test then the Elastic Limit will

display some yield phenomena So omit any undesirable results we just take the Yield portion of the

results as reference

In the process of the experiment the most important part to attend to is the attaching of the strain

gauge because the gaugersquos purpose is to measure the strain developed during the test and this strain

might be very small If the gaugersquos angle change during the test ie is not well attached this will affect

the accuracy of the measurements of Poissonrsquos ratio and Youngrsquos modulus

55

The materials provided by the manufacturer are SUM 23 and SUM 43 steel round bars and these two

types of materials have been through different heat treatment processes so they can be sub-divided

further into untreated material heat-treated material and black surface heat treated material for the two

materials with heat treatment the treatment process and finished are different In the end we only have

the mechanical properties that were calculated after our research of these materials

All of the specifications are identical to those shown in figure 3-6

341 SUM 23

Fig 3-11 SUM 23 Untreated Material

Number 7 10

Hardness(HRB) 74 75

Yield Stress (MPa) 448 440

Tensile Strength (MPa) 544 560

Poissonrsquos Ratio 029 027

Youngrsquos Modulus (GPa) 203 210

Cut-off Area Shrinking () 42 41

Elongation () 1125 1011

Table 3-5 Mechanical Properties of SUM 23 Untreated

56

Stress-Strain Diagram

(a)

(b)

57

Fig 3-12 Stress-Strain Diagrams for (a) 7 Round Bar and (b) 10 Round Bar

Cut-Off Area

(a)

(b)

Fig 3-13 Cut-Off Area of (a) 7 Round Bar and (b) 10 Round Bar

58

SUM 23 Nickel Round Bar

Fig 3-14 SUM 23 Nickel Material

Number 1 2 3 4

Hardness(HRB) 48 50 49 48

Yield Stress (MPa) 370 370 380 400

Tensile Strength (MPa) 455 451 450 450

Poissonrsquos Ratio 028 046 029 026

Youngrsquos Modulus (GPa) 243 303 246 206

Cut-off Area Shrinking () 803 803 726 601

Elongation () 566 65 602 647

Table 3-6 Mechanical Properties of SUM 23 Nickel

59

Stress-Strain Diagram

(a)

60

(b)

(c)

(d)

61

Fig 3-15 Stress-Strain Diagrams for (a) 1 Round Bar (b) 2 Round Bar (c) 3 Round Bar and (d)

4 Round Bar

Cut-Off Area

(a)

(b)

62

(c)

(d)

Fig 3-16 Cut-Off Area of (a) 1 Round Bar (b) 2 Round Bar (c) 3 Round Bar and (d) 4 Round

Bar

63

SUM 23 Black Surface Round Bar

Fig 3-17 SUM 23 Black Surface Material

Number 1 2 3

Hardness(HRB) 51 50 51

Yield Stress (MPa) 378 371 369

Tensile Strength (MPa) 467 465 464

Poissonrsquos Ratio 03 016 04

Youngrsquos Modulus (GPa) 215 266 266

Cut-off Area Shrinking () 986 94 848

Elongation () 748 805 761

Table 3-7 Mechanical Properties of SUM 23 Black Surface Material

64

Stress-Strain Diagram

(a)

(b)

65

(c)

Fig 3-18 Stress-Strain Diagrams for (a) 1 Round Bar 2 Round Bar and (c) 3 Round Bar

Cut-Off Surface

(a)

66

(b)

(c)

Fig 3-19 Cut-Off Surface of (a) 1 Round Bar 2 Round Bar and (c) 3 Round Bar

67

342 SUM 43

Fig 3-20 Untreated SUM 43 Untreated Material

Number 1 5

Hardness(HRB) 76 75

Yield Stress (MPa) 572 594

Tensile Strength (MPa) 743 785

Poissonrsquos Ratio 027 029

Youngrsquos Modulus (GPa) 200 202

Cut-off Area Shrinking () 338 2944

Elongation () 857 894

Table 3-8 Mechanical Properties of SUM 43 Untreated

68

Stress-Strain Diagrams

(a)

(b)

Fig 3-21 Stress-Strain Diagrams for SUM 43 (a) 1 Round Bar and (b) 5 Round Bar

69

Cut-Off Area

(a)

(b)

Fig 3-22 Cut-Off Area of SUM 43 (a) 1 Round Bar and (b) 5 Round Bar

70

SUM 43 Nickel Round Bar

Fig 3-23 SUM 43 Nickel Material

Number 4 5

Hardness(HRB) 51 50

Yield Stress (MPa) 1580 1544

Tensile Strength (MPa) 1639 1625

Poissonrsquos Ratio 03 028

Youngrsquos Modulus (GPa) 194 201

Cut-off Area Shrinking () 1697 137

Elongation () 376 265

Table 3-9 Mechanical Properties of SUM 43 Nickel

71

Stress-Strain Diagrams

(a)

(b)

Fig 3-24 Stress-Strain Diagrams for (a) 4 Round Bar and (b) 5 Round Bar

72

Cut-Off Area

(a)

(b)

Fig 3-25 Cut-Off Area of (a) 4 Round Bar and (b) 5 Round Bar

73

SUM 43 Black Surface Material

Fig 3-26 SUM 43 Black Surface Material

Number 3 5

Hardness(HRB) 56 56

Yield Stress (MPa) 1416 1361

Tensile Strength (MPa) 1591 1402

Poissonrsquos Ratio 029 031

Youngrsquos Modulus (GPa) 200 202

Cut-off Area Shrinking () 139 124

Elongation () 24 24

Table 3-10 Mechanical Properties of SUM 43 Black Surface Material

74

Stress-Strain Diagrams

0 2 4 6 8 10 12 14

-200

0

200

400

600

800

1000

1200

1400

1600

1800

應力 (MPa)

應變()

(a)

0 2 4 6 8 10

-200

0

200

400

600

800

1000

1200

1400

1600

應力

(MPa)

位移 ()

(b)

Fig 3-27 Stress-Strain Diagrams for (a) 3 Round Bar and (b) 5 Round Bar

(Note These curves were formulated using Visual Solutions Inc VisSim Software)

75

Cut-Off Area

(a)

(b)

Fig 3-28 Cut-Off Area of (a) 3 Round Bar and (b) 5 Round Bar

76

The force value (N) was retrieved from the Universal Testing Machine

The Poissonrsquos Ratio (ε) is calculated as

ε =

the values for the Poissonrsquos Ratio are in average around 0297

The Youngrsquos Modulus (E) is calculated as

E =

Where

Stress =

Cross-sectional Area =

where D is the Diameter

The value for D was in average around 1258 mm

The values shown by the computer because there is Slippage phenomena between the Clamp and the

specimen will not be taken into consideration for the elongation strain and Youngrsquos modulus and we will

refer to the values that we have meticulously calculated

77

Chapter 4 AR COATING IN DEPTH

41 Experimentrsquos Purpose and Principles

By means of a vacuum chamber and several other instruments we intend to apply Anti-Reflective

Coating using deposition process to a laser diode and in this way reduce its refraction so as to make it

lose less light in the process of amplification and we can control certain wavelengths we want produced

for certain desired applications in our case we are attempting to re-create a Bose-Einstein Condensate

An optimal BEC apparatus is shown in figure 4-1

Fig 4-1 BEC Apparatus

The main point of this experiment is to build a vacuum chamber system attach all the instrumentation

needed (Vacuum pump deposition meter and voltmeter) and use it to apply AR coating to a laser diode

After we have accomplished the AR coating other team will be in charge of designing the BEC apparatus

and use the results of our research

78

42 Experimentrsquos Equipment

421 Vacuum Chamber

For this research we designed a vacuum chamber whose main body is shown in figure 4-2 Its

dimensions are

Width 240 mm

Length 240 mm

Height 200 mm

Outer Diameter 4 in

Inner Diameter 15 in

Fig 4-2 Vacuum Chamber Main Body

The chamber is made up of 6 pass ways pass way A is the connection with the Laser Deposition

Equipment pass way B is the connection with the Turbo Pump and pass way C is for the connection with

the Deposition Source

A

C

B

79

Pass way C is for the deposition source as mentioned above This is a system where a thermal

resistance is heated by passing a high current through it which heats up a filament boat (made of tungsten)

where the material to be evaporated is place We control the temperature as such that the material will

evaporate and the heat will not cause the filament boat to crack

Because P = Isup2 R (where P is power I is current and R is resistance) to avoid the current to flow

where it is not desired we decided that the material for the Thermocouple shown in figure 4-3 should be

Copper ᴓ 63 mm We choose it that way because Copper has very good heat dissipation characteristics

and the resistance value is low It can reduce the value of the current enough to make the thermocouple to

create heat

Fig 4-3 Thermocouple

To the thermocouple we attach the tungsten filament boat We need to take notice of materials to be

used in this design because when using high current the tungsten filament boar will heat up and so the

material must be able to keep up with the heating potential of tungsten and has a low coefficient of heat

dissipation to avoid the tungsten to fail when heating up and therefore not evaporating Considering all

this we decide to use Stainless Steel

Because this clamp will be assembled inside the chamber after many revisions it was determined it

will have the shape shown in figure 4-4

Fig 4-4 Filament Boat Clamp Design

80

For the tungsten filament boat we bought the product from a distributor The dimensions are

Length 100 mm

Width 10 mm

Height 1 mm

Our thermocouple is 15 in but the pass way C is 4 in so we need to attach a Flange that connects

15in to 4in Because these specifications are quite difficult to achieve by Milling we had to use

electrical wire cutting

For the laser clamping system where the laser that is going to be AR coated will be placed will be

connected to pass way A the assembly is shown in figure 4-5 below

Fig 4-5 Cover Assembly

For this design we used an O-ring instead of a gasket so as to save time The design of the assembly

where the laser will be placed is shown in figure 4-6

Fig 4-6 Upper Cover Inner Assembly

D

E

F

81

Point D is the plate in the assembly where the laser diode will be fixed Because of the easy

processing we decide to use Aluminum and it is screwed to the top cover Point E is the connection for

the Quartz crystal resonator and it is designed in the same as point F in this way the results of the quartz

microbalance system will be more accurate in real time Point F is the final resting place for the laser

diode We use a Thor Labs Base with dimensions of ᴓ 9mm and ᴓ 56mm for two different size laser

diodes It just needs to be plugged in for easy installation

From figure 4-6 we know that the system needs signal system connections and because of the

change in temperature inside the chamber this could affect the functioning of the quartz microbalance so

we also need to install water tubes for cooling This is shown in figure 4-7 below

Fig 4-7 Diagram of Upper Cover Connections

In figure 4-8 we show the Feed through connections and their functions

Fig 4-8 Feed through Diagram

82

1 SQM-160 wire 5 Laser Connection 1 (Vin)

2 SQM-160 (G) 6 Laser Connection 2 (G)

3 K-Type-1 7 Laser Connection 3 (PD)

4 K-Type-2 8 Not In Use

The fully assembled chamber is shown in figure 4-9

Fig 4-9 Fully Assembled Chamber

422 Quartz Crystal Microbalance

For measuring the deposition on our target for coating we used the Inficon SQM-160 RateThickness

Monitor It is an easy to use instrument for measuring many types of thin-film coatings as shown in

figure 4-10

(a) Front Panel (b) Back Panel

Fig 4-10 Inficon SQM-160

83

Table 4-1 shows the technical specifications for this equipment

Number of sensors 2 Standard 4 additional optional

Sensor Frequency Range 40 MHz ~ 60 MHz

Reference Frequency Accuracy 002

Thickness Display Resolution 1 Aring

Thickness Resolution 015 Aring (Std) 0037 Aring (Hi Res)

Density of Stored Films 05-9999 gmcc

Tooling 10-399

Z-Factor 010-1000

Final Thickness 0000-9999k Aring

Measurement Period 15 to 2 sec

Simulation Mode Yes

Frequency Mode Yes

Rate Resolution 011 Arings

Dual Crystal Yes

Etch Mode Yes

Crystal Tooling 10-399

Crystal Fail Min Max 40 to 60 MHz 41 to 61 MHz

Power 100-120 200-240~plusmn10 nominal 20W

Operation Environment 0degC ~ 50degC

0 ~ 80 RH non-condensing

0 ~ 2000 meters

Class 1 Equipment

Pollution Degree 2

Rack Dimensions 885mm x 2127mm x 1969mm

Weight 27 kg

Table 4-1 Inficon SQM-160 RateThickness Monitor Specs

84

To the SQM-160 we need to connect an Oscillator We use the Sigma Instruments Remote Oscillator

Ser No 2 268 as shown in figure 4-11

Fig 4-11 Sigma Instruments Remote Oscillator

The connections diagram is shown in figure 4-12

Fig 4-12 SQM-160 Connections Diagram

85

423 Turbo Pump

For our experiments we used the Pfeiffer TCP 015 Electronic Drive Unit shown below in figure 4-13

Table 4-2 shows the technical specifications for this equipment

(a) Front Panel (b) Back Panel

Fig 4-13 Pfeiffer TCP 015 Electronic Drive

Connection Voltage (100V) 90-112

Mains Frequency 5060 Hz

Start-up Current 22 A

Nominal Frequency 1500 Hz

Rotation Speed 10V = 1500Hz plusmn2

Analog Output Current 10 V = 25 A plusmn 5

Rotation Speed Switchpoint 750 Hz

Works Setting 8 min

Permissible Ambient Temperature 0degC ~ 40degC

Dimensions Front Panel 1285mm x 1063mm

Insertion Length 227mm

Weight 27 Kg

Table 4-2 Pfeiffer TCP 015 Electronic Drive Specs

86

The connections diagram is shown in figure 4-14

Fig 4-14Connections Diagram for Pfeiffer TCP 015

To measure the pressure inside the chamber we use the Granville Phillips 375 Convectron Vacuum

Pressure Controller shown in figure 4-15

(a) Front Panel (b) Back Panel

Fig 4-15 Granville Phillips 375 Convectron

87

Its dimensions are shown in figure 4-16

Fig 4-16 Dimensions of Convectron

Table 4-3 shows the technical specifications for this equipment

Table 4-3 Granville Phillips 375 Convectron Vacuum Pressure Controller Specs

88

424 Multimeter

For our experiment we used the Keithley 2000 Digital Multimeter as shown in figure 4-17

(a) Front Panel (b) Back Panel

Fig 4-17 Keithley Model 2000 6-12-Digit Digital Multimeter

Its technical specifications are shown in table 4-4

Table 4-4 Keithley Model 2000 6-12-Digit Digital Multimeter Specs

89

43 Experiment Procedure

1 Connecting together the equipment and the chamber

(1) We first connect the resonator to the thickness monitor and connect the other side to the

chamber

(2) We now connect the flexible tubes to the turbo pump on one side and to the chamber on the

other

(3) We need to check that tubes are tightly connected to avoid any leaks in the vacuum pumping

process which will not allow us to get to our goal of Torr As shown in figure 4-18

(4) Connect the convectron to the system as shown in figure 4-19

Fig 4-18 checking for leaks using alcohol

Fig 4-19 Convectron attached to System

90

(5) Attach the clamps of the Multimeter to the bottom of the chamber as shown in figure 4-20

(6) Place the Quartz crystal in place

(7) Close tight vacuum chamber

(8) Connect all electrical appliances to power source

Fig 4-20 Multimeter Connections

2 Starting up the System

(1) We turn on all the devices as such Check all systems are ready to function Reset all values

that might be left over from previous tests

(2) Start the thickness monitor and set all values for this experiment In our case we got to testing

the system but not actual coating So we used the simulation mode of the thickness monitor as

shown in figure 4-21

Fig 4-21 Simulation Mode

91

(3) Start the turbo pump Make sure the lid on the vacuum chamber is tightly closed

(4) Start convectron and record initial pressure

(5) Start Multimeter and record initial current

3 Coating Process

(1) If we have the deposition material inside the filament boat the power source for the high

current must be started as well

(2) Record all initial values for thickness current pressure

(3) For an ideal experiment we need a thickness of around 101 nm a pressure of Torr and

a current of 300 A

44 Results

From previous experiments we have shown that we can turn a LED into a laser by means of AR

Coating In figure 4-22 shown below we can compare the actual results of a Diode before and after AR

coating From the blue line we can see that when the diode is at a current of 15mA its light will change

from LED to laser and if we look at the red line its critical current is around 30 to 35 mA

Fig 4-22 AR Coating Comparison for Laser Diodes

This means that the light emitted is not as strong as if the diode had been coated because inside the

chamber there must be some excitation first so the reflectivity of both sides inside the diode must be high

So because of the coating in one of the sides we have opened a door and let the light come out so the

critical current is risen as such and will be higher value than that of before the coating

92

In the following figures we can see the difference between before and after coating in a material The

thickness is around 1016 nm for this material

Fig 4-23 Before Coating

Fig 4-24 After Coating

93

Chapter 5 CONCLUSIONS AND RECOMMENDATIONS

51 Conclusions

For the first part of this independent study taking into consideration the data that came out of our

research and that sent by the provider we can say

1 SUM 23 after heat treatment will unexpectedly develop cracking in the middle of the tensile

testing process and suddenly break

2 Itrsquos possible that in the process of heat treatment to the SUM 23 material the treatment was not

uniform and this will create a pre-loaded moment force on one side that pushes on the other side

of the specimen resulting in material deformation

3 In the process of attaching the strain gauges to the materials it is very easy to make errors due to

poor adhesion or sudden removal in the tensile testing process

For our second part of the independent study the following can be made

1 At the beginning of this independent study we had no idea what Bose-Einstein Condensate was

or what was its purpose After much literature we finally comprehended the basic principles to

put into practice for our research

2 Our systemrsquos basic working principles and equipmentrsquos complexity are a little difficult to grasp

but hopefully we were able to understand enough of it

3 Theoretically from relation between the power and current we can know the advantages and

disadvantages of AR Coating

4 We were able to assemble the system and run test on its functions Even though we were able to

do this there is still much more work left to do with this system

52 Recommendations

For the Tensile Testing the following can be said

1 Ask the provider to check on the process of heat treatment on the SUM 23 material and give

them the information we have gathered through our test so they can correct for the mechanical

properties found if any change is needed

2 To avoid the problem of the inaccuracy of the poor adhesion of strain gauges we can attach

multiple strain gauges to the same one specimen so as to correlate data and improve our results

For the AR Coating the following can be said

1 We need to make sure that there are no physical defects on the main body of the chamber so as to

achieve maximum efficiency in the vacuum process If there was then the vacuum will arrive to

certain point and then start to decrease

2 It would be preferable to add some sort of visual aid that will allow the user to check the inside of

the chamber without actually opening it This will help us determine at what times we should

manipulate the current to better evaporate the substrate

94

REFERENCES

[1] A L Window Strain Gauge Technology Elsevier Applied Science London and New York 2nd

Edition 1992

[2] CC Perry and HR Lissner Strain Gauge Primer McGraw-Hill Book Co Inc New York 1955

[3] James W Dally William F Riley McGraw-Hill 1978

[4] University of Colorado Boulder BEC - What is it and where did the idea come from

httpwwwcoloradoeduphysics2000becwhat_is_ithtml

[5] Ultraslow Light amp Bose-Einstein Condensates Two-way Control with Coherent Light amp Atom

Fields Harvard Hau Lab Dr Lene Vestergaard Hau Optics amp Photonics News 16 1995

[6] The Art of Taming Light Ultra-slow and Stopped Light Harvard Hau Lab Dr Lene

Vestergaard Hau Europhysics News 2004

[7] Nonlinear Optics Shocking Superfluids Harvard Hau Lab Dr Lene Vestergaard Hau Nature

Physics 2007

[8] Model P3 Strain Indicator and Recorder Instruction Manual Vishay Micro-Measurements 2005

[9] Granville-Phillips Series 375 Convectron Vacuum Gauge Controller Instruction Manual Brooks

Automation 2008

[10] Effect of Film Thickness on the Validity of the Sauerbrey Equation for Hydrated Polyelectrolyte

Films Vogt Lin Wu White 2004

[11] Quartz Crystal Microbalance Study of DNA Immobilization and Hybridization for DNA Sensor

Development Chang Zhao 2008

[12] Installation of Strain Gages with SR-4 PrecoatAdhesive Vishay Micro-Measurements 2005

[13] Strain Gauge Measurement ndash A Tutorial National Instruments 1998

[14] Correlation between Vickers Hardness Number and Yield Stress of Cold-Formed Products

Yavuz Tekkaya

[15] httpsenwikipediaorg

Page 30: PC Hinge Materials Testing and AR Laser Diode Coating

30

The microbalance uses Quartz as the resonator Quartz is one member of the family of crystals that

experience the Piezoelectric Effect

Piezoelectricity is the charge that accumulates in certain solid materials in response to applied

mechanical stress It means electricity resulting from pressure It was discovered in 1880 by Jacques and

Pierre Curie It is understood as the linear electromechanical interaction between the mechanical and the

electrical state in crystalline materials with no inversion symmetry It is a reversible process in that

materials exhibiting direct piezoelectricity also exhibit the reverse This means that the internal generation

of electrical resulting from applied mechanical force and vice versa

By using the piezoelectric effect we can probe as an acoustic resonance by electrical means Applying

alternating current to the quartz crystal induces oscillations This creates a shear wave We can use these

qualities to determine the resonance frequency at high accuracy

The frequency of oscillation of the crystal is partially dependent in the thickness of the crystal During

normal operation all the variables are held constant so a change in thickness correlates directly to a

change in frequency As mass is deposited or etched away the thickness increases or decreases and so the

frequency of oscillation changes accordingly With some simplifying assumptions the frequency change

can be quantified and correlated precisely to the mass change using the Sauerbreyrsquos Equation

Developed by G Sauerbrey in 1959 it is a method for correlating changes in the oscillation

frequency of a piezoelectric crystal with the mass deposited on it It is defined as below

Where f0 is the Resonant frequency Δf is the Frequency change Δm is the mass change A is the

piezoelectrically active area of the crystal q is the Density of quartz (2648 gcmsup3) and μq is the Shear

modulus of quarts(2947x gcmssup2)

Because the film is treated as an extension of thickness Sauerbreyrsquos equation only applies to systems

in which the following 3 conditions are met

Deposited mass must be rigid

Deposited mass must be distributed evenly

The frequency change

lt002

If the change is greater than 2 the Z-match method must be used to determine the change in mass

It is defined as

Where fL is the frequency of the loaded crystal fU is the resonant frequency Nq is the frequency

constant (1668x HzAring) Δm is the mass change A is the piezoelectrically active area of the crystal

31

q is the density of quartz Z is the method constant f is the density of film μq Is the shear modulus of

quarts and μf is the shear modulus of film

The Sauerbrey equation cannot be applied to systems under liquid medium

The crystals are seed crystals plated with gold on both top and bottom for applications A crystal is

shown in figure 2-21 The QCM consists of a thin piezoelectric plate with electrodes evaporated on both

sides Due to the piezoelectric effect AC voltage across the electrodes induces a shear deformation and

vice versa The electromechanical coupling provides a simple way to detect an acoustic resonance by

electrical means

The Z also called Z-factor is a constant value for different materials and it is shown together with the

density of different materials in table 2-2 below

Fig 2-21 QCM Crystals

The Oscillator of the SQM-160 is shown in figure 2-22 and the equivalent circuit for the Resonant

Oscillator is shown in figure 2-23

Fig 2-22 SQM-160 Oscillator

32

Fig 2-23 Oscillator Circuit

33

Table 2-2 Z-Ratios for Different Materials

Table 2-2 Continued

34

Table 2-2 Continued

35

Table 2-2 Continued

36

Table 2-2 Continued

37

Table 2-2 Continued

38

Table 2-2 Continued

235 Vacuum Chamber System

Vacuum Evaporation is the process of depositing thin films of materials onto surfaces The technique

consists of pumping a vacuum chamber to pressures of less than torr and heating a material to

produce a flux of vapor in order to deposit the material onto a surface The material to be vaporized is

typically heated until its vapor pressure is high enough to produce a flux several Angstrom per second by

using an electrically resistive heater or bombardment by a high voltage beam The process was invented

by Henri Nestle in 1886 for food industry

In here the system has been pumped to a vacuum of Torr When a high current is passed

through the filament boat the filament boat is heated over the desired metal evaporation temperature and

so evaporation starts When the evaporation process is finished and the metal cools down crystals

condensate in the surface of the wafer From the weight of the evaporated material the distance between

the filament boat and the wafer we are able to calculate the deposition thickness and we can also use the

mass detector follower like the Quartz crystal resonator microbalance system In the process of

evaporation we usually use a board in between the filament boat and the wafer This is because before we

arrive to the desired evaporation temperature there will be some impurities that will be vaporized in the

controlled environment so we first use a small current and the board in between to get rid of those

impurities and this raises the purity of the deposition material

39

A vacuum evaporation system is shown in figure 2-24

Fig 2-24 Vacuum Evaporation System

Rough Vacuum 760 ~ 1 torr

Medium Vacuum 1 ~ torr

High Vacuum ~ torr

Ultra-High Vacuum Lower than torr

Table 2-3 Classification of Vacuum

For our study we need to use a Turbo Pump A regular turbo pump is shown in figure 2-25

Fig 2-25 Turbo Pump

For our research we used the Pfeiffer TCP 015 Electronic Drive Unit and Granville Phillips 375

Convectron shown below in figure 2-26

40

Fig 2-26 Control and Measurement Equipment

The electronic drive controls the turbo pump and the Convectron measures the pressure inside our

chamber The turbo pump is a type of vacuum pump used to maintain high vacuum Most turbo pumps

are centrifugal When we start the pumping we need to use a mechanical pump so as to decrease the

pressure inside the system from constant atmospheric pressure to torr and then the use dispersion

pump to continue the vacuum until we get to the desired pressure We need to notice though when we

start the dispersion pump we canrsquot turn off the mechanical pump and they both need to run together If

we need to turn off the pumping we first turn off the dispersion pump wait for it to completely stop and

then turn off the mechanical pump

Our completely assembled system is shown in figure 2-27 below

Fig 2-27 Complete System

41

Chapter 3 TENSILE TESTING IN DEPTH

31 Experimentrsquos Purpose and Principles

By means of Universal testing machine and Strain gauges we were able to observe discuss and

analyze the phenomena created when a specimen of certain material is manipulated under an external load

and determine the stress strain and deformation values later we can use the graphing methods of

stress-strain diagram to describe it

The main point of this experiment is that after the tensile specimen is tested use computer analysis

and the actual strain data and after statistical adjustment make the final results report (Tensile testing

experiment is in accordance with ASTM E8)

32 Experimentrsquos Equipment

321 Universal Testing Machine

For the materials testing experiment part of this research we use a Universal Testing Machine as

shown in figure 31 The maximum load it can apply is 100 Ton After the test specimen is secured on the

device with the use of instrumentation the load exerted and the effects of this become apparent on the

specimen and even the smallest of changes can be recorded For our research we used the Chun Yen

Testing Machines Co Ltd 100 Ton Micro Computer Universal Tensile Tester

Fig 31 Universal Testing Machine

42

Table 31 shows the specifications for this machine

Max Capacity 100 Ton

Accuracy plusmn1

Tension (mm) Max Space 1150mm

Grip for Rod 20-70mm

Ram Stroke 250mm

Effective Column Interval 940mm

Crosshead Speed 300mmmin

Testing Speed 0-50mmmin

Volume of Machine 1700times1000times3350mm(LtimesWtimesH)

Volume of Control Panel 1000times800times1500mm(LtimesWtimesH)

Weight 8000kg

Power 3∮220V 20A

Computer AMD K6-2-350

OS Windows XP

Screen 15rdquo CRT

Table 3-1 Chun Yen Testing Machine Specs Table

The connections diagram is shown in figure 3-2

Fig 3-2 Diagram for System Connections

43

When the test specimen is placed when the external force is applied the Load Cell can measure the

size of the applied force and the Encoder measures the expansion rate of change The Local Controller

receives all the information from the 2 units after arranging the results they are displayed in the

computer and they can be afterwards submitted for more complex analysis such as Finite Element

Analysis and we can get the Stress-Strain Diagram

322 Strain Measurement Equipment

The equipment used in our research provides a four-channel measurement that means we can use up

to 4 strain gauges at a time to do our measurements and provides 3 different bridge arrangements as

shown in figure 3-3

(a) (b) (c)

Fig 3-3 Input Connections for Strain Indicator

Figure 3-3 (a) is the Quarter Bridge (b) is the Half Bridge and (c) is the Full Bridge and Transducers

For our study we used the Quarter Bridge and use the Strain Gauge values to decide the position of the

connecting wires The Strain indicator is shown in figure 3-4

Fig 3-4 Vishay Micro-Measurements Model P3 Strain Indicator and Recorder

44

Input Connections Tool Free eccentric lever release

4-channel input

Wire diameter16-28AWG

Bridge Configurations Quarter- Half- and Full Bridge

Bridge Impedance 60-2000Ω

Display 128 64 pixel FSTN positive gray LCD

Data Conversion AD Converter filter

Measurement Range Resolution Strain Range plusmn155mVV

Resolution plusmn00005mVV

Measurement Accuracy plusmn01 of reading plusmn3 counts

Gage Factor Control 0500-9900

Balance Control Software either manual or automatic

Bridge Excitation 15VDC nominal

Communication Interface USB Cable Included

Data Storage Removable Media Card

Shunt Calibration Across bridge completion resistors controlled

by software When Gage Factor=200

120Ω350Ω1000Ω

Analog Output Value 0 to 25V max

Ranges plusmn320 microε plusmn3200 microε plusmn32000 microε

Error 05 output voltage +5mV

Max Error 14 output voltage + 20mV

Update rate 480 samplessec

Output Load 2000Ω

Power Battery Two Alkaline D cells

Battery life 400 hours typ

USB 5V 100mA

Operational Environment Temperature 0-50

Humidity Up to 90 Non-condensing

Case Aluminum Alloy

Size and Weight 228times152times152(mm) 20(kg)

Table 3-2 Vishay Micro-Measurements Model P3 Strain Indicator and Recorder Specs

45

323 Strain Gauge

The strain gaugersquos main basic principle is to use a resistancersquos characteristics to measure the strain

The inside connections of the strain indicator are shown in figure 3-5

Fig 3-5 Inner Connections

As shown above this is a quarter-bridge connection We connect equal-length 3 wires to the 2

connections allowed by the strain gauge wire 1 and 3 can be used to cancel out the effects of temperature

to the resistance and because of the addition of wires 1 and 3 wire 2 can directly measure the experiment

results from the strain gauge and therefore the strain developed with no influence of temperature

If there were no two measuring leads then the relations will be

R 4 =R g +2R L

Where Rg is the Strain Gauge Value and RL is the wire resistance then

4

4

R

R=

Lg

g

RR

R

2

=

gL

gg

RR

RR

21

amp

4

4

R

R=

g

g

R

R(1- L)

Where L is the Signal Loss Factor and so

L =gL

gL

RR

RR

21

2

g

L

R

2R if

g

L

R

2Rltlt1

46

(Actual Value R g =120R L =08g

L

R

2Ris always much smaller than 1)

R 4 =R g +2R LR 2 =R 3 =rR gR 1 =R g 32 RR =0

V 0 =V 2)1( r

r

(

4

4

R

R-

1

1

R

R)

The first term describes loss attenuation effects second term describes loss of balancing capabilities

effects

V 0 =V 2)1( r

r

[

)2

(Lg

g

RR

R

+

T

Lg

g

RR

R

)

2( + T

Lg

L

RR

R

)

2

2( -(

g

g

R

R) T ]

The first term describes loss attenuation effects and loss of balancing capabilities effects the second

third and fourth terms describe the temperature effects on the wire

For the three-wire method we have

L =gL

gL

RR

RR

1

g

L

R

R if

g

L

R

Rltlt1

V 0 =V 2)1( r

r

[

)(Lg

g

RR

R

+

T

Lg

g

RR

R

)( + T

Lg

L

RR

R

)

2( -

T

Lg

g

RR

R

)( - T

Lg

L

RR

R

)

2( ]

V 0 = V2)1( r

r

)(

Lg

g

RR

R

In the last four terms inside parenthesis we can see the effects of temperature being cancelled out and the

effect on first term is not great so this is the reason why in our research we use three wires

47

324 Specimen Measurements

The tensile specimens used in this research are compliant of ASTM E8 Tensile parameters as shown

in figure 3-6

Fig 3-6 Tensile Specimen

Diameter

D(mm)

Gauge

Length

G(mm)

Smallest

Arc

Radius

R(mm)

Shortest

Area

A(mm)

Total

Length

L(mm)

Clamping

Area

Length

B(mm)

Clamping

Area

Diameter

C(mm)

Bar 125 02 625 01 gt10 gt75 ~ 145 ~ 35 20

Table 3-3 Specifications for Round Bar

33 Experiment Procedure

1 Attaching the Strain Gauge to the Tensile Specimen

(1) Prepare 1 ASTM E8 compliant tensile specimen round bar as shown in figure 3-7

(2) Prepare Strain Gauge as those described in table 3-4

(3) Prepare other consumables and adhesive agent such as epoxy adhesive or

cyanoacrylate adhesive as shown in figure 3-8

48

Fig 3-7 Actual Tensile Specimen

Fig 3-8 Other Materials Used (Such as Alcohol gauze transparent tape adhesive)

Gage Type

EA-06-120LZ-120E

Resistance in ohms at 24∘C

1200plusmn03

Gage Factor at 24∘C

2075plusmn05

Transverse Sensitivity at 24∘C

(+07plusmn02)

Table 3-4 Specifications for Strain Gauge

2 Attaching Strain Gauge

As shown in following figures we shall explain the attachment of the strain gauge

(1) Use sand paper and a rasp to clean thoroughly the surface where the strain gauge will be

attached to

49

(a)

(2) Use alcohol to wash the surface where the strain gauge will be attached and use gauze to rub

it off

(b)

(3) Find a clean surface and clean it with alcohol and gauze

(c)

(4) Place the strain gauge in the clean surface Use a piece of transparent tape on top of the strain

gauge after securely placed rip it off the surface carefully

50

(d)

(5) Use a piece of white paper to mark the place where the strain gauge will be attached and in

this way we can make sure that the strain gauge will be placed as horizontally and vertically

correct as possible

(e)

(6) In the place where we had our mark place the strain gauge

(f)

(7) Carefully lift one side of the tape and apply some of the adhesive agent to both the strain

gauge and specimenrsquos surface

(g)

51

(8) We need to make sure that the gauge and the specimen will be firmly attached so we gently

apply pressure with our thumb

(h)

(9) After the adhesive is fully dry we can carefully rip off the tape

(i)

(10) We need to do the whole process twice one for the horizontally placed strain gauge and one

for the vertically placed strain gauge

52

(j)

(11) We now proceed to solder the wires to the strain gauge

(k)

(12) After soldering we use a Volt Multimeter to measure that there is no contact between wires

If there is none then the specimen is ready for testing

(l)

(13) We now need to measure a 5cm distance and mark it to check and compare the elongation

before and after the tensile testing

(m)

53

Fig 3-9 Specimen-Strain Gauge Process

3 Tensile Test

(1) Enter the computer application that controls the tensile testing machine

(2) Turn on the tensile testing machine main switch

(3) Adjust the hydraulic pump to go back to its original position

(4) Bring the lowering motor down to a distance enough so as to attach the tensile specimen to the

system open the clamps and secure the specimen

(a)

(5) Connect all the necessary wires to the strain indicator equipment

54

(b)

(6) Start the ascending motor and wait for the expansion

(c)

Fig 3-10 Specimen-Tensile Testing Process

4 Start the Test

(1) Enter the software application and enter some variables needed for the experiment in the

specific screen

(2) Go back to the main screen and press the [測試] (measure) button to start the test and auto

recording in the software

(3) After the specimen breaks the mechanical device will automatically stop and ask the user to

enter the total displacement We take out the specimen from the testing machine and adjust the

machinersquos position back to its original position

(4) Save the results information

(5) Record the results from the strain indicator

34 Results

From this experiment we can get the Poissonrsquos Ratio Youngrsquos Modulus and Yield Strength etc and

because of the slippage phenomenon in the clamp at the moment of the test then the Elastic Limit will

display some yield phenomena So omit any undesirable results we just take the Yield portion of the

results as reference

In the process of the experiment the most important part to attend to is the attaching of the strain

gauge because the gaugersquos purpose is to measure the strain developed during the test and this strain

might be very small If the gaugersquos angle change during the test ie is not well attached this will affect

the accuracy of the measurements of Poissonrsquos ratio and Youngrsquos modulus

55

The materials provided by the manufacturer are SUM 23 and SUM 43 steel round bars and these two

types of materials have been through different heat treatment processes so they can be sub-divided

further into untreated material heat-treated material and black surface heat treated material for the two

materials with heat treatment the treatment process and finished are different In the end we only have

the mechanical properties that were calculated after our research of these materials

All of the specifications are identical to those shown in figure 3-6

341 SUM 23

Fig 3-11 SUM 23 Untreated Material

Number 7 10

Hardness(HRB) 74 75

Yield Stress (MPa) 448 440

Tensile Strength (MPa) 544 560

Poissonrsquos Ratio 029 027

Youngrsquos Modulus (GPa) 203 210

Cut-off Area Shrinking () 42 41

Elongation () 1125 1011

Table 3-5 Mechanical Properties of SUM 23 Untreated

56

Stress-Strain Diagram

(a)

(b)

57

Fig 3-12 Stress-Strain Diagrams for (a) 7 Round Bar and (b) 10 Round Bar

Cut-Off Area

(a)

(b)

Fig 3-13 Cut-Off Area of (a) 7 Round Bar and (b) 10 Round Bar

58

SUM 23 Nickel Round Bar

Fig 3-14 SUM 23 Nickel Material

Number 1 2 3 4

Hardness(HRB) 48 50 49 48

Yield Stress (MPa) 370 370 380 400

Tensile Strength (MPa) 455 451 450 450

Poissonrsquos Ratio 028 046 029 026

Youngrsquos Modulus (GPa) 243 303 246 206

Cut-off Area Shrinking () 803 803 726 601

Elongation () 566 65 602 647

Table 3-6 Mechanical Properties of SUM 23 Nickel

59

Stress-Strain Diagram

(a)

60

(b)

(c)

(d)

61

Fig 3-15 Stress-Strain Diagrams for (a) 1 Round Bar (b) 2 Round Bar (c) 3 Round Bar and (d)

4 Round Bar

Cut-Off Area

(a)

(b)

62

(c)

(d)

Fig 3-16 Cut-Off Area of (a) 1 Round Bar (b) 2 Round Bar (c) 3 Round Bar and (d) 4 Round

Bar

63

SUM 23 Black Surface Round Bar

Fig 3-17 SUM 23 Black Surface Material

Number 1 2 3

Hardness(HRB) 51 50 51

Yield Stress (MPa) 378 371 369

Tensile Strength (MPa) 467 465 464

Poissonrsquos Ratio 03 016 04

Youngrsquos Modulus (GPa) 215 266 266

Cut-off Area Shrinking () 986 94 848

Elongation () 748 805 761

Table 3-7 Mechanical Properties of SUM 23 Black Surface Material

64

Stress-Strain Diagram

(a)

(b)

65

(c)

Fig 3-18 Stress-Strain Diagrams for (a) 1 Round Bar 2 Round Bar and (c) 3 Round Bar

Cut-Off Surface

(a)

66

(b)

(c)

Fig 3-19 Cut-Off Surface of (a) 1 Round Bar 2 Round Bar and (c) 3 Round Bar

67

342 SUM 43

Fig 3-20 Untreated SUM 43 Untreated Material

Number 1 5

Hardness(HRB) 76 75

Yield Stress (MPa) 572 594

Tensile Strength (MPa) 743 785

Poissonrsquos Ratio 027 029

Youngrsquos Modulus (GPa) 200 202

Cut-off Area Shrinking () 338 2944

Elongation () 857 894

Table 3-8 Mechanical Properties of SUM 43 Untreated

68

Stress-Strain Diagrams

(a)

(b)

Fig 3-21 Stress-Strain Diagrams for SUM 43 (a) 1 Round Bar and (b) 5 Round Bar

69

Cut-Off Area

(a)

(b)

Fig 3-22 Cut-Off Area of SUM 43 (a) 1 Round Bar and (b) 5 Round Bar

70

SUM 43 Nickel Round Bar

Fig 3-23 SUM 43 Nickel Material

Number 4 5

Hardness(HRB) 51 50

Yield Stress (MPa) 1580 1544

Tensile Strength (MPa) 1639 1625

Poissonrsquos Ratio 03 028

Youngrsquos Modulus (GPa) 194 201

Cut-off Area Shrinking () 1697 137

Elongation () 376 265

Table 3-9 Mechanical Properties of SUM 43 Nickel

71

Stress-Strain Diagrams

(a)

(b)

Fig 3-24 Stress-Strain Diagrams for (a) 4 Round Bar and (b) 5 Round Bar

72

Cut-Off Area

(a)

(b)

Fig 3-25 Cut-Off Area of (a) 4 Round Bar and (b) 5 Round Bar

73

SUM 43 Black Surface Material

Fig 3-26 SUM 43 Black Surface Material

Number 3 5

Hardness(HRB) 56 56

Yield Stress (MPa) 1416 1361

Tensile Strength (MPa) 1591 1402

Poissonrsquos Ratio 029 031

Youngrsquos Modulus (GPa) 200 202

Cut-off Area Shrinking () 139 124

Elongation () 24 24

Table 3-10 Mechanical Properties of SUM 43 Black Surface Material

74

Stress-Strain Diagrams

0 2 4 6 8 10 12 14

-200

0

200

400

600

800

1000

1200

1400

1600

1800

應力 (MPa)

應變()

(a)

0 2 4 6 8 10

-200

0

200

400

600

800

1000

1200

1400

1600

應力

(MPa)

位移 ()

(b)

Fig 3-27 Stress-Strain Diagrams for (a) 3 Round Bar and (b) 5 Round Bar

(Note These curves were formulated using Visual Solutions Inc VisSim Software)

75

Cut-Off Area

(a)

(b)

Fig 3-28 Cut-Off Area of (a) 3 Round Bar and (b) 5 Round Bar

76

The force value (N) was retrieved from the Universal Testing Machine

The Poissonrsquos Ratio (ε) is calculated as

ε =

the values for the Poissonrsquos Ratio are in average around 0297

The Youngrsquos Modulus (E) is calculated as

E =

Where

Stress =

Cross-sectional Area =

where D is the Diameter

The value for D was in average around 1258 mm

The values shown by the computer because there is Slippage phenomena between the Clamp and the

specimen will not be taken into consideration for the elongation strain and Youngrsquos modulus and we will

refer to the values that we have meticulously calculated

77

Chapter 4 AR COATING IN DEPTH

41 Experimentrsquos Purpose and Principles

By means of a vacuum chamber and several other instruments we intend to apply Anti-Reflective

Coating using deposition process to a laser diode and in this way reduce its refraction so as to make it

lose less light in the process of amplification and we can control certain wavelengths we want produced

for certain desired applications in our case we are attempting to re-create a Bose-Einstein Condensate

An optimal BEC apparatus is shown in figure 4-1

Fig 4-1 BEC Apparatus

The main point of this experiment is to build a vacuum chamber system attach all the instrumentation

needed (Vacuum pump deposition meter and voltmeter) and use it to apply AR coating to a laser diode

After we have accomplished the AR coating other team will be in charge of designing the BEC apparatus

and use the results of our research

78

42 Experimentrsquos Equipment

421 Vacuum Chamber

For this research we designed a vacuum chamber whose main body is shown in figure 4-2 Its

dimensions are

Width 240 mm

Length 240 mm

Height 200 mm

Outer Diameter 4 in

Inner Diameter 15 in

Fig 4-2 Vacuum Chamber Main Body

The chamber is made up of 6 pass ways pass way A is the connection with the Laser Deposition

Equipment pass way B is the connection with the Turbo Pump and pass way C is for the connection with

the Deposition Source

A

C

B

79

Pass way C is for the deposition source as mentioned above This is a system where a thermal

resistance is heated by passing a high current through it which heats up a filament boat (made of tungsten)

where the material to be evaporated is place We control the temperature as such that the material will

evaporate and the heat will not cause the filament boat to crack

Because P = Isup2 R (where P is power I is current and R is resistance) to avoid the current to flow

where it is not desired we decided that the material for the Thermocouple shown in figure 4-3 should be

Copper ᴓ 63 mm We choose it that way because Copper has very good heat dissipation characteristics

and the resistance value is low It can reduce the value of the current enough to make the thermocouple to

create heat

Fig 4-3 Thermocouple

To the thermocouple we attach the tungsten filament boat We need to take notice of materials to be

used in this design because when using high current the tungsten filament boar will heat up and so the

material must be able to keep up with the heating potential of tungsten and has a low coefficient of heat

dissipation to avoid the tungsten to fail when heating up and therefore not evaporating Considering all

this we decide to use Stainless Steel

Because this clamp will be assembled inside the chamber after many revisions it was determined it

will have the shape shown in figure 4-4

Fig 4-4 Filament Boat Clamp Design

80

For the tungsten filament boat we bought the product from a distributor The dimensions are

Length 100 mm

Width 10 mm

Height 1 mm

Our thermocouple is 15 in but the pass way C is 4 in so we need to attach a Flange that connects

15in to 4in Because these specifications are quite difficult to achieve by Milling we had to use

electrical wire cutting

For the laser clamping system where the laser that is going to be AR coated will be placed will be

connected to pass way A the assembly is shown in figure 4-5 below

Fig 4-5 Cover Assembly

For this design we used an O-ring instead of a gasket so as to save time The design of the assembly

where the laser will be placed is shown in figure 4-6

Fig 4-6 Upper Cover Inner Assembly

D

E

F

81

Point D is the plate in the assembly where the laser diode will be fixed Because of the easy

processing we decide to use Aluminum and it is screwed to the top cover Point E is the connection for

the Quartz crystal resonator and it is designed in the same as point F in this way the results of the quartz

microbalance system will be more accurate in real time Point F is the final resting place for the laser

diode We use a Thor Labs Base with dimensions of ᴓ 9mm and ᴓ 56mm for two different size laser

diodes It just needs to be plugged in for easy installation

From figure 4-6 we know that the system needs signal system connections and because of the

change in temperature inside the chamber this could affect the functioning of the quartz microbalance so

we also need to install water tubes for cooling This is shown in figure 4-7 below

Fig 4-7 Diagram of Upper Cover Connections

In figure 4-8 we show the Feed through connections and their functions

Fig 4-8 Feed through Diagram

82

1 SQM-160 wire 5 Laser Connection 1 (Vin)

2 SQM-160 (G) 6 Laser Connection 2 (G)

3 K-Type-1 7 Laser Connection 3 (PD)

4 K-Type-2 8 Not In Use

The fully assembled chamber is shown in figure 4-9

Fig 4-9 Fully Assembled Chamber

422 Quartz Crystal Microbalance

For measuring the deposition on our target for coating we used the Inficon SQM-160 RateThickness

Monitor It is an easy to use instrument for measuring many types of thin-film coatings as shown in

figure 4-10

(a) Front Panel (b) Back Panel

Fig 4-10 Inficon SQM-160

83

Table 4-1 shows the technical specifications for this equipment

Number of sensors 2 Standard 4 additional optional

Sensor Frequency Range 40 MHz ~ 60 MHz

Reference Frequency Accuracy 002

Thickness Display Resolution 1 Aring

Thickness Resolution 015 Aring (Std) 0037 Aring (Hi Res)

Density of Stored Films 05-9999 gmcc

Tooling 10-399

Z-Factor 010-1000

Final Thickness 0000-9999k Aring

Measurement Period 15 to 2 sec

Simulation Mode Yes

Frequency Mode Yes

Rate Resolution 011 Arings

Dual Crystal Yes

Etch Mode Yes

Crystal Tooling 10-399

Crystal Fail Min Max 40 to 60 MHz 41 to 61 MHz

Power 100-120 200-240~plusmn10 nominal 20W

Operation Environment 0degC ~ 50degC

0 ~ 80 RH non-condensing

0 ~ 2000 meters

Class 1 Equipment

Pollution Degree 2

Rack Dimensions 885mm x 2127mm x 1969mm

Weight 27 kg

Table 4-1 Inficon SQM-160 RateThickness Monitor Specs

84

To the SQM-160 we need to connect an Oscillator We use the Sigma Instruments Remote Oscillator

Ser No 2 268 as shown in figure 4-11

Fig 4-11 Sigma Instruments Remote Oscillator

The connections diagram is shown in figure 4-12

Fig 4-12 SQM-160 Connections Diagram

85

423 Turbo Pump

For our experiments we used the Pfeiffer TCP 015 Electronic Drive Unit shown below in figure 4-13

Table 4-2 shows the technical specifications for this equipment

(a) Front Panel (b) Back Panel

Fig 4-13 Pfeiffer TCP 015 Electronic Drive

Connection Voltage (100V) 90-112

Mains Frequency 5060 Hz

Start-up Current 22 A

Nominal Frequency 1500 Hz

Rotation Speed 10V = 1500Hz plusmn2

Analog Output Current 10 V = 25 A plusmn 5

Rotation Speed Switchpoint 750 Hz

Works Setting 8 min

Permissible Ambient Temperature 0degC ~ 40degC

Dimensions Front Panel 1285mm x 1063mm

Insertion Length 227mm

Weight 27 Kg

Table 4-2 Pfeiffer TCP 015 Electronic Drive Specs

86

The connections diagram is shown in figure 4-14

Fig 4-14Connections Diagram for Pfeiffer TCP 015

To measure the pressure inside the chamber we use the Granville Phillips 375 Convectron Vacuum

Pressure Controller shown in figure 4-15

(a) Front Panel (b) Back Panel

Fig 4-15 Granville Phillips 375 Convectron

87

Its dimensions are shown in figure 4-16

Fig 4-16 Dimensions of Convectron

Table 4-3 shows the technical specifications for this equipment

Table 4-3 Granville Phillips 375 Convectron Vacuum Pressure Controller Specs

88

424 Multimeter

For our experiment we used the Keithley 2000 Digital Multimeter as shown in figure 4-17

(a) Front Panel (b) Back Panel

Fig 4-17 Keithley Model 2000 6-12-Digit Digital Multimeter

Its technical specifications are shown in table 4-4

Table 4-4 Keithley Model 2000 6-12-Digit Digital Multimeter Specs

89

43 Experiment Procedure

1 Connecting together the equipment and the chamber

(1) We first connect the resonator to the thickness monitor and connect the other side to the

chamber

(2) We now connect the flexible tubes to the turbo pump on one side and to the chamber on the

other

(3) We need to check that tubes are tightly connected to avoid any leaks in the vacuum pumping

process which will not allow us to get to our goal of Torr As shown in figure 4-18

(4) Connect the convectron to the system as shown in figure 4-19

Fig 4-18 checking for leaks using alcohol

Fig 4-19 Convectron attached to System

90

(5) Attach the clamps of the Multimeter to the bottom of the chamber as shown in figure 4-20

(6) Place the Quartz crystal in place

(7) Close tight vacuum chamber

(8) Connect all electrical appliances to power source

Fig 4-20 Multimeter Connections

2 Starting up the System

(1) We turn on all the devices as such Check all systems are ready to function Reset all values

that might be left over from previous tests

(2) Start the thickness monitor and set all values for this experiment In our case we got to testing

the system but not actual coating So we used the simulation mode of the thickness monitor as

shown in figure 4-21

Fig 4-21 Simulation Mode

91

(3) Start the turbo pump Make sure the lid on the vacuum chamber is tightly closed

(4) Start convectron and record initial pressure

(5) Start Multimeter and record initial current

3 Coating Process

(1) If we have the deposition material inside the filament boat the power source for the high

current must be started as well

(2) Record all initial values for thickness current pressure

(3) For an ideal experiment we need a thickness of around 101 nm a pressure of Torr and

a current of 300 A

44 Results

From previous experiments we have shown that we can turn a LED into a laser by means of AR

Coating In figure 4-22 shown below we can compare the actual results of a Diode before and after AR

coating From the blue line we can see that when the diode is at a current of 15mA its light will change

from LED to laser and if we look at the red line its critical current is around 30 to 35 mA

Fig 4-22 AR Coating Comparison for Laser Diodes

This means that the light emitted is not as strong as if the diode had been coated because inside the

chamber there must be some excitation first so the reflectivity of both sides inside the diode must be high

So because of the coating in one of the sides we have opened a door and let the light come out so the

critical current is risen as such and will be higher value than that of before the coating

92

In the following figures we can see the difference between before and after coating in a material The

thickness is around 1016 nm for this material

Fig 4-23 Before Coating

Fig 4-24 After Coating

93

Chapter 5 CONCLUSIONS AND RECOMMENDATIONS

51 Conclusions

For the first part of this independent study taking into consideration the data that came out of our

research and that sent by the provider we can say

1 SUM 23 after heat treatment will unexpectedly develop cracking in the middle of the tensile

testing process and suddenly break

2 Itrsquos possible that in the process of heat treatment to the SUM 23 material the treatment was not

uniform and this will create a pre-loaded moment force on one side that pushes on the other side

of the specimen resulting in material deformation

3 In the process of attaching the strain gauges to the materials it is very easy to make errors due to

poor adhesion or sudden removal in the tensile testing process

For our second part of the independent study the following can be made

1 At the beginning of this independent study we had no idea what Bose-Einstein Condensate was

or what was its purpose After much literature we finally comprehended the basic principles to

put into practice for our research

2 Our systemrsquos basic working principles and equipmentrsquos complexity are a little difficult to grasp

but hopefully we were able to understand enough of it

3 Theoretically from relation between the power and current we can know the advantages and

disadvantages of AR Coating

4 We were able to assemble the system and run test on its functions Even though we were able to

do this there is still much more work left to do with this system

52 Recommendations

For the Tensile Testing the following can be said

1 Ask the provider to check on the process of heat treatment on the SUM 23 material and give

them the information we have gathered through our test so they can correct for the mechanical

properties found if any change is needed

2 To avoid the problem of the inaccuracy of the poor adhesion of strain gauges we can attach

multiple strain gauges to the same one specimen so as to correlate data and improve our results

For the AR Coating the following can be said

1 We need to make sure that there are no physical defects on the main body of the chamber so as to

achieve maximum efficiency in the vacuum process If there was then the vacuum will arrive to

certain point and then start to decrease

2 It would be preferable to add some sort of visual aid that will allow the user to check the inside of

the chamber without actually opening it This will help us determine at what times we should

manipulate the current to better evaporate the substrate

94

REFERENCES

[1] A L Window Strain Gauge Technology Elsevier Applied Science London and New York 2nd

Edition 1992

[2] CC Perry and HR Lissner Strain Gauge Primer McGraw-Hill Book Co Inc New York 1955

[3] James W Dally William F Riley McGraw-Hill 1978

[4] University of Colorado Boulder BEC - What is it and where did the idea come from

httpwwwcoloradoeduphysics2000becwhat_is_ithtml

[5] Ultraslow Light amp Bose-Einstein Condensates Two-way Control with Coherent Light amp Atom

Fields Harvard Hau Lab Dr Lene Vestergaard Hau Optics amp Photonics News 16 1995

[6] The Art of Taming Light Ultra-slow and Stopped Light Harvard Hau Lab Dr Lene

Vestergaard Hau Europhysics News 2004

[7] Nonlinear Optics Shocking Superfluids Harvard Hau Lab Dr Lene Vestergaard Hau Nature

Physics 2007

[8] Model P3 Strain Indicator and Recorder Instruction Manual Vishay Micro-Measurements 2005

[9] Granville-Phillips Series 375 Convectron Vacuum Gauge Controller Instruction Manual Brooks

Automation 2008

[10] Effect of Film Thickness on the Validity of the Sauerbrey Equation for Hydrated Polyelectrolyte

Films Vogt Lin Wu White 2004

[11] Quartz Crystal Microbalance Study of DNA Immobilization and Hybridization for DNA Sensor

Development Chang Zhao 2008

[12] Installation of Strain Gages with SR-4 PrecoatAdhesive Vishay Micro-Measurements 2005

[13] Strain Gauge Measurement ndash A Tutorial National Instruments 1998

[14] Correlation between Vickers Hardness Number and Yield Stress of Cold-Formed Products

Yavuz Tekkaya

[15] httpsenwikipediaorg

Page 31: PC Hinge Materials Testing and AR Laser Diode Coating

31

q is the density of quartz Z is the method constant f is the density of film μq Is the shear modulus of

quarts and μf is the shear modulus of film

The Sauerbrey equation cannot be applied to systems under liquid medium

The crystals are seed crystals plated with gold on both top and bottom for applications A crystal is

shown in figure 2-21 The QCM consists of a thin piezoelectric plate with electrodes evaporated on both

sides Due to the piezoelectric effect AC voltage across the electrodes induces a shear deformation and

vice versa The electromechanical coupling provides a simple way to detect an acoustic resonance by

electrical means

The Z also called Z-factor is a constant value for different materials and it is shown together with the

density of different materials in table 2-2 below

Fig 2-21 QCM Crystals

The Oscillator of the SQM-160 is shown in figure 2-22 and the equivalent circuit for the Resonant

Oscillator is shown in figure 2-23

Fig 2-22 SQM-160 Oscillator

32

Fig 2-23 Oscillator Circuit

33

Table 2-2 Z-Ratios for Different Materials

Table 2-2 Continued

34

Table 2-2 Continued

35

Table 2-2 Continued

36

Table 2-2 Continued

37

Table 2-2 Continued

38

Table 2-2 Continued

235 Vacuum Chamber System

Vacuum Evaporation is the process of depositing thin films of materials onto surfaces The technique

consists of pumping a vacuum chamber to pressures of less than torr and heating a material to

produce a flux of vapor in order to deposit the material onto a surface The material to be vaporized is

typically heated until its vapor pressure is high enough to produce a flux several Angstrom per second by

using an electrically resistive heater or bombardment by a high voltage beam The process was invented

by Henri Nestle in 1886 for food industry

In here the system has been pumped to a vacuum of Torr When a high current is passed

through the filament boat the filament boat is heated over the desired metal evaporation temperature and

so evaporation starts When the evaporation process is finished and the metal cools down crystals

condensate in the surface of the wafer From the weight of the evaporated material the distance between

the filament boat and the wafer we are able to calculate the deposition thickness and we can also use the

mass detector follower like the Quartz crystal resonator microbalance system In the process of

evaporation we usually use a board in between the filament boat and the wafer This is because before we

arrive to the desired evaporation temperature there will be some impurities that will be vaporized in the

controlled environment so we first use a small current and the board in between to get rid of those

impurities and this raises the purity of the deposition material

39

A vacuum evaporation system is shown in figure 2-24

Fig 2-24 Vacuum Evaporation System

Rough Vacuum 760 ~ 1 torr

Medium Vacuum 1 ~ torr

High Vacuum ~ torr

Ultra-High Vacuum Lower than torr

Table 2-3 Classification of Vacuum

For our study we need to use a Turbo Pump A regular turbo pump is shown in figure 2-25

Fig 2-25 Turbo Pump

For our research we used the Pfeiffer TCP 015 Electronic Drive Unit and Granville Phillips 375

Convectron shown below in figure 2-26

40

Fig 2-26 Control and Measurement Equipment

The electronic drive controls the turbo pump and the Convectron measures the pressure inside our

chamber The turbo pump is a type of vacuum pump used to maintain high vacuum Most turbo pumps

are centrifugal When we start the pumping we need to use a mechanical pump so as to decrease the

pressure inside the system from constant atmospheric pressure to torr and then the use dispersion

pump to continue the vacuum until we get to the desired pressure We need to notice though when we

start the dispersion pump we canrsquot turn off the mechanical pump and they both need to run together If

we need to turn off the pumping we first turn off the dispersion pump wait for it to completely stop and

then turn off the mechanical pump

Our completely assembled system is shown in figure 2-27 below

Fig 2-27 Complete System

41

Chapter 3 TENSILE TESTING IN DEPTH

31 Experimentrsquos Purpose and Principles

By means of Universal testing machine and Strain gauges we were able to observe discuss and

analyze the phenomena created when a specimen of certain material is manipulated under an external load

and determine the stress strain and deformation values later we can use the graphing methods of

stress-strain diagram to describe it

The main point of this experiment is that after the tensile specimen is tested use computer analysis

and the actual strain data and after statistical adjustment make the final results report (Tensile testing

experiment is in accordance with ASTM E8)

32 Experimentrsquos Equipment

321 Universal Testing Machine

For the materials testing experiment part of this research we use a Universal Testing Machine as

shown in figure 31 The maximum load it can apply is 100 Ton After the test specimen is secured on the

device with the use of instrumentation the load exerted and the effects of this become apparent on the

specimen and even the smallest of changes can be recorded For our research we used the Chun Yen

Testing Machines Co Ltd 100 Ton Micro Computer Universal Tensile Tester

Fig 31 Universal Testing Machine

42

Table 31 shows the specifications for this machine

Max Capacity 100 Ton

Accuracy plusmn1

Tension (mm) Max Space 1150mm

Grip for Rod 20-70mm

Ram Stroke 250mm

Effective Column Interval 940mm

Crosshead Speed 300mmmin

Testing Speed 0-50mmmin

Volume of Machine 1700times1000times3350mm(LtimesWtimesH)

Volume of Control Panel 1000times800times1500mm(LtimesWtimesH)

Weight 8000kg

Power 3∮220V 20A

Computer AMD K6-2-350

OS Windows XP

Screen 15rdquo CRT

Table 3-1 Chun Yen Testing Machine Specs Table

The connections diagram is shown in figure 3-2

Fig 3-2 Diagram for System Connections

43

When the test specimen is placed when the external force is applied the Load Cell can measure the

size of the applied force and the Encoder measures the expansion rate of change The Local Controller

receives all the information from the 2 units after arranging the results they are displayed in the

computer and they can be afterwards submitted for more complex analysis such as Finite Element

Analysis and we can get the Stress-Strain Diagram

322 Strain Measurement Equipment

The equipment used in our research provides a four-channel measurement that means we can use up

to 4 strain gauges at a time to do our measurements and provides 3 different bridge arrangements as

shown in figure 3-3

(a) (b) (c)

Fig 3-3 Input Connections for Strain Indicator

Figure 3-3 (a) is the Quarter Bridge (b) is the Half Bridge and (c) is the Full Bridge and Transducers

For our study we used the Quarter Bridge and use the Strain Gauge values to decide the position of the

connecting wires The Strain indicator is shown in figure 3-4

Fig 3-4 Vishay Micro-Measurements Model P3 Strain Indicator and Recorder

44

Input Connections Tool Free eccentric lever release

4-channel input

Wire diameter16-28AWG

Bridge Configurations Quarter- Half- and Full Bridge

Bridge Impedance 60-2000Ω

Display 128 64 pixel FSTN positive gray LCD

Data Conversion AD Converter filter

Measurement Range Resolution Strain Range plusmn155mVV

Resolution plusmn00005mVV

Measurement Accuracy plusmn01 of reading plusmn3 counts

Gage Factor Control 0500-9900

Balance Control Software either manual or automatic

Bridge Excitation 15VDC nominal

Communication Interface USB Cable Included

Data Storage Removable Media Card

Shunt Calibration Across bridge completion resistors controlled

by software When Gage Factor=200

120Ω350Ω1000Ω

Analog Output Value 0 to 25V max

Ranges plusmn320 microε plusmn3200 microε plusmn32000 microε

Error 05 output voltage +5mV

Max Error 14 output voltage + 20mV

Update rate 480 samplessec

Output Load 2000Ω

Power Battery Two Alkaline D cells

Battery life 400 hours typ

USB 5V 100mA

Operational Environment Temperature 0-50

Humidity Up to 90 Non-condensing

Case Aluminum Alloy

Size and Weight 228times152times152(mm) 20(kg)

Table 3-2 Vishay Micro-Measurements Model P3 Strain Indicator and Recorder Specs

45

323 Strain Gauge

The strain gaugersquos main basic principle is to use a resistancersquos characteristics to measure the strain

The inside connections of the strain indicator are shown in figure 3-5

Fig 3-5 Inner Connections

As shown above this is a quarter-bridge connection We connect equal-length 3 wires to the 2

connections allowed by the strain gauge wire 1 and 3 can be used to cancel out the effects of temperature

to the resistance and because of the addition of wires 1 and 3 wire 2 can directly measure the experiment

results from the strain gauge and therefore the strain developed with no influence of temperature

If there were no two measuring leads then the relations will be

R 4 =R g +2R L

Where Rg is the Strain Gauge Value and RL is the wire resistance then

4

4

R

R=

Lg

g

RR

R

2

=

gL

gg

RR

RR

21

amp

4

4

R

R=

g

g

R

R(1- L)

Where L is the Signal Loss Factor and so

L =gL

gL

RR

RR

21

2

g

L

R

2R if

g

L

R

2Rltlt1

46

(Actual Value R g =120R L =08g

L

R

2Ris always much smaller than 1)

R 4 =R g +2R LR 2 =R 3 =rR gR 1 =R g 32 RR =0

V 0 =V 2)1( r

r

(

4

4

R

R-

1

1

R

R)

The first term describes loss attenuation effects second term describes loss of balancing capabilities

effects

V 0 =V 2)1( r

r

[

)2

(Lg

g

RR

R

+

T

Lg

g

RR

R

)

2( + T

Lg

L

RR

R

)

2

2( -(

g

g

R

R) T ]

The first term describes loss attenuation effects and loss of balancing capabilities effects the second

third and fourth terms describe the temperature effects on the wire

For the three-wire method we have

L =gL

gL

RR

RR

1

g

L

R

R if

g

L

R

Rltlt1

V 0 =V 2)1( r

r

[

)(Lg

g

RR

R

+

T

Lg

g

RR

R

)( + T

Lg

L

RR

R

)

2( -

T

Lg

g

RR

R

)( - T

Lg

L

RR

R

)

2( ]

V 0 = V2)1( r

r

)(

Lg

g

RR

R

In the last four terms inside parenthesis we can see the effects of temperature being cancelled out and the

effect on first term is not great so this is the reason why in our research we use three wires

47

324 Specimen Measurements

The tensile specimens used in this research are compliant of ASTM E8 Tensile parameters as shown

in figure 3-6

Fig 3-6 Tensile Specimen

Diameter

D(mm)

Gauge

Length

G(mm)

Smallest

Arc

Radius

R(mm)

Shortest

Area

A(mm)

Total

Length

L(mm)

Clamping

Area

Length

B(mm)

Clamping

Area

Diameter

C(mm)

Bar 125 02 625 01 gt10 gt75 ~ 145 ~ 35 20

Table 3-3 Specifications for Round Bar

33 Experiment Procedure

1 Attaching the Strain Gauge to the Tensile Specimen

(1) Prepare 1 ASTM E8 compliant tensile specimen round bar as shown in figure 3-7

(2) Prepare Strain Gauge as those described in table 3-4

(3) Prepare other consumables and adhesive agent such as epoxy adhesive or

cyanoacrylate adhesive as shown in figure 3-8

48

Fig 3-7 Actual Tensile Specimen

Fig 3-8 Other Materials Used (Such as Alcohol gauze transparent tape adhesive)

Gage Type

EA-06-120LZ-120E

Resistance in ohms at 24∘C

1200plusmn03

Gage Factor at 24∘C

2075plusmn05

Transverse Sensitivity at 24∘C

(+07plusmn02)

Table 3-4 Specifications for Strain Gauge

2 Attaching Strain Gauge

As shown in following figures we shall explain the attachment of the strain gauge

(1) Use sand paper and a rasp to clean thoroughly the surface where the strain gauge will be

attached to

49

(a)

(2) Use alcohol to wash the surface where the strain gauge will be attached and use gauze to rub

it off

(b)

(3) Find a clean surface and clean it with alcohol and gauze

(c)

(4) Place the strain gauge in the clean surface Use a piece of transparent tape on top of the strain

gauge after securely placed rip it off the surface carefully

50

(d)

(5) Use a piece of white paper to mark the place where the strain gauge will be attached and in

this way we can make sure that the strain gauge will be placed as horizontally and vertically

correct as possible

(e)

(6) In the place where we had our mark place the strain gauge

(f)

(7) Carefully lift one side of the tape and apply some of the adhesive agent to both the strain

gauge and specimenrsquos surface

(g)

51

(8) We need to make sure that the gauge and the specimen will be firmly attached so we gently

apply pressure with our thumb

(h)

(9) After the adhesive is fully dry we can carefully rip off the tape

(i)

(10) We need to do the whole process twice one for the horizontally placed strain gauge and one

for the vertically placed strain gauge

52

(j)

(11) We now proceed to solder the wires to the strain gauge

(k)

(12) After soldering we use a Volt Multimeter to measure that there is no contact between wires

If there is none then the specimen is ready for testing

(l)

(13) We now need to measure a 5cm distance and mark it to check and compare the elongation

before and after the tensile testing

(m)

53

Fig 3-9 Specimen-Strain Gauge Process

3 Tensile Test

(1) Enter the computer application that controls the tensile testing machine

(2) Turn on the tensile testing machine main switch

(3) Adjust the hydraulic pump to go back to its original position

(4) Bring the lowering motor down to a distance enough so as to attach the tensile specimen to the

system open the clamps and secure the specimen

(a)

(5) Connect all the necessary wires to the strain indicator equipment

54

(b)

(6) Start the ascending motor and wait for the expansion

(c)

Fig 3-10 Specimen-Tensile Testing Process

4 Start the Test

(1) Enter the software application and enter some variables needed for the experiment in the

specific screen

(2) Go back to the main screen and press the [測試] (measure) button to start the test and auto

recording in the software

(3) After the specimen breaks the mechanical device will automatically stop and ask the user to

enter the total displacement We take out the specimen from the testing machine and adjust the

machinersquos position back to its original position

(4) Save the results information

(5) Record the results from the strain indicator

34 Results

From this experiment we can get the Poissonrsquos Ratio Youngrsquos Modulus and Yield Strength etc and

because of the slippage phenomenon in the clamp at the moment of the test then the Elastic Limit will

display some yield phenomena So omit any undesirable results we just take the Yield portion of the

results as reference

In the process of the experiment the most important part to attend to is the attaching of the strain

gauge because the gaugersquos purpose is to measure the strain developed during the test and this strain

might be very small If the gaugersquos angle change during the test ie is not well attached this will affect

the accuracy of the measurements of Poissonrsquos ratio and Youngrsquos modulus

55

The materials provided by the manufacturer are SUM 23 and SUM 43 steel round bars and these two

types of materials have been through different heat treatment processes so they can be sub-divided

further into untreated material heat-treated material and black surface heat treated material for the two

materials with heat treatment the treatment process and finished are different In the end we only have

the mechanical properties that were calculated after our research of these materials

All of the specifications are identical to those shown in figure 3-6

341 SUM 23

Fig 3-11 SUM 23 Untreated Material

Number 7 10

Hardness(HRB) 74 75

Yield Stress (MPa) 448 440

Tensile Strength (MPa) 544 560

Poissonrsquos Ratio 029 027

Youngrsquos Modulus (GPa) 203 210

Cut-off Area Shrinking () 42 41

Elongation () 1125 1011

Table 3-5 Mechanical Properties of SUM 23 Untreated

56

Stress-Strain Diagram

(a)

(b)

57

Fig 3-12 Stress-Strain Diagrams for (a) 7 Round Bar and (b) 10 Round Bar

Cut-Off Area

(a)

(b)

Fig 3-13 Cut-Off Area of (a) 7 Round Bar and (b) 10 Round Bar

58

SUM 23 Nickel Round Bar

Fig 3-14 SUM 23 Nickel Material

Number 1 2 3 4

Hardness(HRB) 48 50 49 48

Yield Stress (MPa) 370 370 380 400

Tensile Strength (MPa) 455 451 450 450

Poissonrsquos Ratio 028 046 029 026

Youngrsquos Modulus (GPa) 243 303 246 206

Cut-off Area Shrinking () 803 803 726 601

Elongation () 566 65 602 647

Table 3-6 Mechanical Properties of SUM 23 Nickel

59

Stress-Strain Diagram

(a)

60

(b)

(c)

(d)

61

Fig 3-15 Stress-Strain Diagrams for (a) 1 Round Bar (b) 2 Round Bar (c) 3 Round Bar and (d)

4 Round Bar

Cut-Off Area

(a)

(b)

62

(c)

(d)

Fig 3-16 Cut-Off Area of (a) 1 Round Bar (b) 2 Round Bar (c) 3 Round Bar and (d) 4 Round

Bar

63

SUM 23 Black Surface Round Bar

Fig 3-17 SUM 23 Black Surface Material

Number 1 2 3

Hardness(HRB) 51 50 51

Yield Stress (MPa) 378 371 369

Tensile Strength (MPa) 467 465 464

Poissonrsquos Ratio 03 016 04

Youngrsquos Modulus (GPa) 215 266 266

Cut-off Area Shrinking () 986 94 848

Elongation () 748 805 761

Table 3-7 Mechanical Properties of SUM 23 Black Surface Material

64

Stress-Strain Diagram

(a)

(b)

65

(c)

Fig 3-18 Stress-Strain Diagrams for (a) 1 Round Bar 2 Round Bar and (c) 3 Round Bar

Cut-Off Surface

(a)

66

(b)

(c)

Fig 3-19 Cut-Off Surface of (a) 1 Round Bar 2 Round Bar and (c) 3 Round Bar

67

342 SUM 43

Fig 3-20 Untreated SUM 43 Untreated Material

Number 1 5

Hardness(HRB) 76 75

Yield Stress (MPa) 572 594

Tensile Strength (MPa) 743 785

Poissonrsquos Ratio 027 029

Youngrsquos Modulus (GPa) 200 202

Cut-off Area Shrinking () 338 2944

Elongation () 857 894

Table 3-8 Mechanical Properties of SUM 43 Untreated

68

Stress-Strain Diagrams

(a)

(b)

Fig 3-21 Stress-Strain Diagrams for SUM 43 (a) 1 Round Bar and (b) 5 Round Bar

69

Cut-Off Area

(a)

(b)

Fig 3-22 Cut-Off Area of SUM 43 (a) 1 Round Bar and (b) 5 Round Bar

70

SUM 43 Nickel Round Bar

Fig 3-23 SUM 43 Nickel Material

Number 4 5

Hardness(HRB) 51 50

Yield Stress (MPa) 1580 1544

Tensile Strength (MPa) 1639 1625

Poissonrsquos Ratio 03 028

Youngrsquos Modulus (GPa) 194 201

Cut-off Area Shrinking () 1697 137

Elongation () 376 265

Table 3-9 Mechanical Properties of SUM 43 Nickel

71

Stress-Strain Diagrams

(a)

(b)

Fig 3-24 Stress-Strain Diagrams for (a) 4 Round Bar and (b) 5 Round Bar

72

Cut-Off Area

(a)

(b)

Fig 3-25 Cut-Off Area of (a) 4 Round Bar and (b) 5 Round Bar

73

SUM 43 Black Surface Material

Fig 3-26 SUM 43 Black Surface Material

Number 3 5

Hardness(HRB) 56 56

Yield Stress (MPa) 1416 1361

Tensile Strength (MPa) 1591 1402

Poissonrsquos Ratio 029 031

Youngrsquos Modulus (GPa) 200 202

Cut-off Area Shrinking () 139 124

Elongation () 24 24

Table 3-10 Mechanical Properties of SUM 43 Black Surface Material

74

Stress-Strain Diagrams

0 2 4 6 8 10 12 14

-200

0

200

400

600

800

1000

1200

1400

1600

1800

應力 (MPa)

應變()

(a)

0 2 4 6 8 10

-200

0

200

400

600

800

1000

1200

1400

1600

應力

(MPa)

位移 ()

(b)

Fig 3-27 Stress-Strain Diagrams for (a) 3 Round Bar and (b) 5 Round Bar

(Note These curves were formulated using Visual Solutions Inc VisSim Software)

75

Cut-Off Area

(a)

(b)

Fig 3-28 Cut-Off Area of (a) 3 Round Bar and (b) 5 Round Bar

76

The force value (N) was retrieved from the Universal Testing Machine

The Poissonrsquos Ratio (ε) is calculated as

ε =

the values for the Poissonrsquos Ratio are in average around 0297

The Youngrsquos Modulus (E) is calculated as

E =

Where

Stress =

Cross-sectional Area =

where D is the Diameter

The value for D was in average around 1258 mm

The values shown by the computer because there is Slippage phenomena between the Clamp and the

specimen will not be taken into consideration for the elongation strain and Youngrsquos modulus and we will

refer to the values that we have meticulously calculated

77

Chapter 4 AR COATING IN DEPTH

41 Experimentrsquos Purpose and Principles

By means of a vacuum chamber and several other instruments we intend to apply Anti-Reflective

Coating using deposition process to a laser diode and in this way reduce its refraction so as to make it

lose less light in the process of amplification and we can control certain wavelengths we want produced

for certain desired applications in our case we are attempting to re-create a Bose-Einstein Condensate

An optimal BEC apparatus is shown in figure 4-1

Fig 4-1 BEC Apparatus

The main point of this experiment is to build a vacuum chamber system attach all the instrumentation

needed (Vacuum pump deposition meter and voltmeter) and use it to apply AR coating to a laser diode

After we have accomplished the AR coating other team will be in charge of designing the BEC apparatus

and use the results of our research

78

42 Experimentrsquos Equipment

421 Vacuum Chamber

For this research we designed a vacuum chamber whose main body is shown in figure 4-2 Its

dimensions are

Width 240 mm

Length 240 mm

Height 200 mm

Outer Diameter 4 in

Inner Diameter 15 in

Fig 4-2 Vacuum Chamber Main Body

The chamber is made up of 6 pass ways pass way A is the connection with the Laser Deposition

Equipment pass way B is the connection with the Turbo Pump and pass way C is for the connection with

the Deposition Source

A

C

B

79

Pass way C is for the deposition source as mentioned above This is a system where a thermal

resistance is heated by passing a high current through it which heats up a filament boat (made of tungsten)

where the material to be evaporated is place We control the temperature as such that the material will

evaporate and the heat will not cause the filament boat to crack

Because P = Isup2 R (where P is power I is current and R is resistance) to avoid the current to flow

where it is not desired we decided that the material for the Thermocouple shown in figure 4-3 should be

Copper ᴓ 63 mm We choose it that way because Copper has very good heat dissipation characteristics

and the resistance value is low It can reduce the value of the current enough to make the thermocouple to

create heat

Fig 4-3 Thermocouple

To the thermocouple we attach the tungsten filament boat We need to take notice of materials to be

used in this design because when using high current the tungsten filament boar will heat up and so the

material must be able to keep up with the heating potential of tungsten and has a low coefficient of heat

dissipation to avoid the tungsten to fail when heating up and therefore not evaporating Considering all

this we decide to use Stainless Steel

Because this clamp will be assembled inside the chamber after many revisions it was determined it

will have the shape shown in figure 4-4

Fig 4-4 Filament Boat Clamp Design

80

For the tungsten filament boat we bought the product from a distributor The dimensions are

Length 100 mm

Width 10 mm

Height 1 mm

Our thermocouple is 15 in but the pass way C is 4 in so we need to attach a Flange that connects

15in to 4in Because these specifications are quite difficult to achieve by Milling we had to use

electrical wire cutting

For the laser clamping system where the laser that is going to be AR coated will be placed will be

connected to pass way A the assembly is shown in figure 4-5 below

Fig 4-5 Cover Assembly

For this design we used an O-ring instead of a gasket so as to save time The design of the assembly

where the laser will be placed is shown in figure 4-6

Fig 4-6 Upper Cover Inner Assembly

D

E

F

81

Point D is the plate in the assembly where the laser diode will be fixed Because of the easy

processing we decide to use Aluminum and it is screwed to the top cover Point E is the connection for

the Quartz crystal resonator and it is designed in the same as point F in this way the results of the quartz

microbalance system will be more accurate in real time Point F is the final resting place for the laser

diode We use a Thor Labs Base with dimensions of ᴓ 9mm and ᴓ 56mm for two different size laser

diodes It just needs to be plugged in for easy installation

From figure 4-6 we know that the system needs signal system connections and because of the

change in temperature inside the chamber this could affect the functioning of the quartz microbalance so

we also need to install water tubes for cooling This is shown in figure 4-7 below

Fig 4-7 Diagram of Upper Cover Connections

In figure 4-8 we show the Feed through connections and their functions

Fig 4-8 Feed through Diagram

82

1 SQM-160 wire 5 Laser Connection 1 (Vin)

2 SQM-160 (G) 6 Laser Connection 2 (G)

3 K-Type-1 7 Laser Connection 3 (PD)

4 K-Type-2 8 Not In Use

The fully assembled chamber is shown in figure 4-9

Fig 4-9 Fully Assembled Chamber

422 Quartz Crystal Microbalance

For measuring the deposition on our target for coating we used the Inficon SQM-160 RateThickness

Monitor It is an easy to use instrument for measuring many types of thin-film coatings as shown in

figure 4-10

(a) Front Panel (b) Back Panel

Fig 4-10 Inficon SQM-160

83

Table 4-1 shows the technical specifications for this equipment

Number of sensors 2 Standard 4 additional optional

Sensor Frequency Range 40 MHz ~ 60 MHz

Reference Frequency Accuracy 002

Thickness Display Resolution 1 Aring

Thickness Resolution 015 Aring (Std) 0037 Aring (Hi Res)

Density of Stored Films 05-9999 gmcc

Tooling 10-399

Z-Factor 010-1000

Final Thickness 0000-9999k Aring

Measurement Period 15 to 2 sec

Simulation Mode Yes

Frequency Mode Yes

Rate Resolution 011 Arings

Dual Crystal Yes

Etch Mode Yes

Crystal Tooling 10-399

Crystal Fail Min Max 40 to 60 MHz 41 to 61 MHz

Power 100-120 200-240~plusmn10 nominal 20W

Operation Environment 0degC ~ 50degC

0 ~ 80 RH non-condensing

0 ~ 2000 meters

Class 1 Equipment

Pollution Degree 2

Rack Dimensions 885mm x 2127mm x 1969mm

Weight 27 kg

Table 4-1 Inficon SQM-160 RateThickness Monitor Specs

84

To the SQM-160 we need to connect an Oscillator We use the Sigma Instruments Remote Oscillator

Ser No 2 268 as shown in figure 4-11

Fig 4-11 Sigma Instruments Remote Oscillator

The connections diagram is shown in figure 4-12

Fig 4-12 SQM-160 Connections Diagram

85

423 Turbo Pump

For our experiments we used the Pfeiffer TCP 015 Electronic Drive Unit shown below in figure 4-13

Table 4-2 shows the technical specifications for this equipment

(a) Front Panel (b) Back Panel

Fig 4-13 Pfeiffer TCP 015 Electronic Drive

Connection Voltage (100V) 90-112

Mains Frequency 5060 Hz

Start-up Current 22 A

Nominal Frequency 1500 Hz

Rotation Speed 10V = 1500Hz plusmn2

Analog Output Current 10 V = 25 A plusmn 5

Rotation Speed Switchpoint 750 Hz

Works Setting 8 min

Permissible Ambient Temperature 0degC ~ 40degC

Dimensions Front Panel 1285mm x 1063mm

Insertion Length 227mm

Weight 27 Kg

Table 4-2 Pfeiffer TCP 015 Electronic Drive Specs

86

The connections diagram is shown in figure 4-14

Fig 4-14Connections Diagram for Pfeiffer TCP 015

To measure the pressure inside the chamber we use the Granville Phillips 375 Convectron Vacuum

Pressure Controller shown in figure 4-15

(a) Front Panel (b) Back Panel

Fig 4-15 Granville Phillips 375 Convectron

87

Its dimensions are shown in figure 4-16

Fig 4-16 Dimensions of Convectron

Table 4-3 shows the technical specifications for this equipment

Table 4-3 Granville Phillips 375 Convectron Vacuum Pressure Controller Specs

88

424 Multimeter

For our experiment we used the Keithley 2000 Digital Multimeter as shown in figure 4-17

(a) Front Panel (b) Back Panel

Fig 4-17 Keithley Model 2000 6-12-Digit Digital Multimeter

Its technical specifications are shown in table 4-4

Table 4-4 Keithley Model 2000 6-12-Digit Digital Multimeter Specs

89

43 Experiment Procedure

1 Connecting together the equipment and the chamber

(1) We first connect the resonator to the thickness monitor and connect the other side to the

chamber

(2) We now connect the flexible tubes to the turbo pump on one side and to the chamber on the

other

(3) We need to check that tubes are tightly connected to avoid any leaks in the vacuum pumping

process which will not allow us to get to our goal of Torr As shown in figure 4-18

(4) Connect the convectron to the system as shown in figure 4-19

Fig 4-18 checking for leaks using alcohol

Fig 4-19 Convectron attached to System

90

(5) Attach the clamps of the Multimeter to the bottom of the chamber as shown in figure 4-20

(6) Place the Quartz crystal in place

(7) Close tight vacuum chamber

(8) Connect all electrical appliances to power source

Fig 4-20 Multimeter Connections

2 Starting up the System

(1) We turn on all the devices as such Check all systems are ready to function Reset all values

that might be left over from previous tests

(2) Start the thickness monitor and set all values for this experiment In our case we got to testing

the system but not actual coating So we used the simulation mode of the thickness monitor as

shown in figure 4-21

Fig 4-21 Simulation Mode

91

(3) Start the turbo pump Make sure the lid on the vacuum chamber is tightly closed

(4) Start convectron and record initial pressure

(5) Start Multimeter and record initial current

3 Coating Process

(1) If we have the deposition material inside the filament boat the power source for the high

current must be started as well

(2) Record all initial values for thickness current pressure

(3) For an ideal experiment we need a thickness of around 101 nm a pressure of Torr and

a current of 300 A

44 Results

From previous experiments we have shown that we can turn a LED into a laser by means of AR

Coating In figure 4-22 shown below we can compare the actual results of a Diode before and after AR

coating From the blue line we can see that when the diode is at a current of 15mA its light will change

from LED to laser and if we look at the red line its critical current is around 30 to 35 mA

Fig 4-22 AR Coating Comparison for Laser Diodes

This means that the light emitted is not as strong as if the diode had been coated because inside the

chamber there must be some excitation first so the reflectivity of both sides inside the diode must be high

So because of the coating in one of the sides we have opened a door and let the light come out so the

critical current is risen as such and will be higher value than that of before the coating

92

In the following figures we can see the difference between before and after coating in a material The

thickness is around 1016 nm for this material

Fig 4-23 Before Coating

Fig 4-24 After Coating

93

Chapter 5 CONCLUSIONS AND RECOMMENDATIONS

51 Conclusions

For the first part of this independent study taking into consideration the data that came out of our

research and that sent by the provider we can say

1 SUM 23 after heat treatment will unexpectedly develop cracking in the middle of the tensile

testing process and suddenly break

2 Itrsquos possible that in the process of heat treatment to the SUM 23 material the treatment was not

uniform and this will create a pre-loaded moment force on one side that pushes on the other side

of the specimen resulting in material deformation

3 In the process of attaching the strain gauges to the materials it is very easy to make errors due to

poor adhesion or sudden removal in the tensile testing process

For our second part of the independent study the following can be made

1 At the beginning of this independent study we had no idea what Bose-Einstein Condensate was

or what was its purpose After much literature we finally comprehended the basic principles to

put into practice for our research

2 Our systemrsquos basic working principles and equipmentrsquos complexity are a little difficult to grasp

but hopefully we were able to understand enough of it

3 Theoretically from relation between the power and current we can know the advantages and

disadvantages of AR Coating

4 We were able to assemble the system and run test on its functions Even though we were able to

do this there is still much more work left to do with this system

52 Recommendations

For the Tensile Testing the following can be said

1 Ask the provider to check on the process of heat treatment on the SUM 23 material and give

them the information we have gathered through our test so they can correct for the mechanical

properties found if any change is needed

2 To avoid the problem of the inaccuracy of the poor adhesion of strain gauges we can attach

multiple strain gauges to the same one specimen so as to correlate data and improve our results

For the AR Coating the following can be said

1 We need to make sure that there are no physical defects on the main body of the chamber so as to

achieve maximum efficiency in the vacuum process If there was then the vacuum will arrive to

certain point and then start to decrease

2 It would be preferable to add some sort of visual aid that will allow the user to check the inside of

the chamber without actually opening it This will help us determine at what times we should

manipulate the current to better evaporate the substrate

94

REFERENCES

[1] A L Window Strain Gauge Technology Elsevier Applied Science London and New York 2nd

Edition 1992

[2] CC Perry and HR Lissner Strain Gauge Primer McGraw-Hill Book Co Inc New York 1955

[3] James W Dally William F Riley McGraw-Hill 1978

[4] University of Colorado Boulder BEC - What is it and where did the idea come from

httpwwwcoloradoeduphysics2000becwhat_is_ithtml

[5] Ultraslow Light amp Bose-Einstein Condensates Two-way Control with Coherent Light amp Atom

Fields Harvard Hau Lab Dr Lene Vestergaard Hau Optics amp Photonics News 16 1995

[6] The Art of Taming Light Ultra-slow and Stopped Light Harvard Hau Lab Dr Lene

Vestergaard Hau Europhysics News 2004

[7] Nonlinear Optics Shocking Superfluids Harvard Hau Lab Dr Lene Vestergaard Hau Nature

Physics 2007

[8] Model P3 Strain Indicator and Recorder Instruction Manual Vishay Micro-Measurements 2005

[9] Granville-Phillips Series 375 Convectron Vacuum Gauge Controller Instruction Manual Brooks

Automation 2008

[10] Effect of Film Thickness on the Validity of the Sauerbrey Equation for Hydrated Polyelectrolyte

Films Vogt Lin Wu White 2004

[11] Quartz Crystal Microbalance Study of DNA Immobilization and Hybridization for DNA Sensor

Development Chang Zhao 2008

[12] Installation of Strain Gages with SR-4 PrecoatAdhesive Vishay Micro-Measurements 2005

[13] Strain Gauge Measurement ndash A Tutorial National Instruments 1998

[14] Correlation between Vickers Hardness Number and Yield Stress of Cold-Formed Products

Yavuz Tekkaya

[15] httpsenwikipediaorg

Page 32: PC Hinge Materials Testing and AR Laser Diode Coating

32

Fig 2-23 Oscillator Circuit

33

Table 2-2 Z-Ratios for Different Materials

Table 2-2 Continued

34

Table 2-2 Continued

35

Table 2-2 Continued

36

Table 2-2 Continued

37

Table 2-2 Continued

38

Table 2-2 Continued

235 Vacuum Chamber System

Vacuum Evaporation is the process of depositing thin films of materials onto surfaces The technique

consists of pumping a vacuum chamber to pressures of less than torr and heating a material to

produce a flux of vapor in order to deposit the material onto a surface The material to be vaporized is

typically heated until its vapor pressure is high enough to produce a flux several Angstrom per second by

using an electrically resistive heater or bombardment by a high voltage beam The process was invented

by Henri Nestle in 1886 for food industry

In here the system has been pumped to a vacuum of Torr When a high current is passed

through the filament boat the filament boat is heated over the desired metal evaporation temperature and

so evaporation starts When the evaporation process is finished and the metal cools down crystals

condensate in the surface of the wafer From the weight of the evaporated material the distance between

the filament boat and the wafer we are able to calculate the deposition thickness and we can also use the

mass detector follower like the Quartz crystal resonator microbalance system In the process of

evaporation we usually use a board in between the filament boat and the wafer This is because before we

arrive to the desired evaporation temperature there will be some impurities that will be vaporized in the

controlled environment so we first use a small current and the board in between to get rid of those

impurities and this raises the purity of the deposition material

39

A vacuum evaporation system is shown in figure 2-24

Fig 2-24 Vacuum Evaporation System

Rough Vacuum 760 ~ 1 torr

Medium Vacuum 1 ~ torr

High Vacuum ~ torr

Ultra-High Vacuum Lower than torr

Table 2-3 Classification of Vacuum

For our study we need to use a Turbo Pump A regular turbo pump is shown in figure 2-25

Fig 2-25 Turbo Pump

For our research we used the Pfeiffer TCP 015 Electronic Drive Unit and Granville Phillips 375

Convectron shown below in figure 2-26

40

Fig 2-26 Control and Measurement Equipment

The electronic drive controls the turbo pump and the Convectron measures the pressure inside our

chamber The turbo pump is a type of vacuum pump used to maintain high vacuum Most turbo pumps

are centrifugal When we start the pumping we need to use a mechanical pump so as to decrease the

pressure inside the system from constant atmospheric pressure to torr and then the use dispersion

pump to continue the vacuum until we get to the desired pressure We need to notice though when we

start the dispersion pump we canrsquot turn off the mechanical pump and they both need to run together If

we need to turn off the pumping we first turn off the dispersion pump wait for it to completely stop and

then turn off the mechanical pump

Our completely assembled system is shown in figure 2-27 below

Fig 2-27 Complete System

41

Chapter 3 TENSILE TESTING IN DEPTH

31 Experimentrsquos Purpose and Principles

By means of Universal testing machine and Strain gauges we were able to observe discuss and

analyze the phenomena created when a specimen of certain material is manipulated under an external load

and determine the stress strain and deformation values later we can use the graphing methods of

stress-strain diagram to describe it

The main point of this experiment is that after the tensile specimen is tested use computer analysis

and the actual strain data and after statistical adjustment make the final results report (Tensile testing

experiment is in accordance with ASTM E8)

32 Experimentrsquos Equipment

321 Universal Testing Machine

For the materials testing experiment part of this research we use a Universal Testing Machine as

shown in figure 31 The maximum load it can apply is 100 Ton After the test specimen is secured on the

device with the use of instrumentation the load exerted and the effects of this become apparent on the

specimen and even the smallest of changes can be recorded For our research we used the Chun Yen

Testing Machines Co Ltd 100 Ton Micro Computer Universal Tensile Tester

Fig 31 Universal Testing Machine

42

Table 31 shows the specifications for this machine

Max Capacity 100 Ton

Accuracy plusmn1

Tension (mm) Max Space 1150mm

Grip for Rod 20-70mm

Ram Stroke 250mm

Effective Column Interval 940mm

Crosshead Speed 300mmmin

Testing Speed 0-50mmmin

Volume of Machine 1700times1000times3350mm(LtimesWtimesH)

Volume of Control Panel 1000times800times1500mm(LtimesWtimesH)

Weight 8000kg

Power 3∮220V 20A

Computer AMD K6-2-350

OS Windows XP

Screen 15rdquo CRT

Table 3-1 Chun Yen Testing Machine Specs Table

The connections diagram is shown in figure 3-2

Fig 3-2 Diagram for System Connections

43

When the test specimen is placed when the external force is applied the Load Cell can measure the

size of the applied force and the Encoder measures the expansion rate of change The Local Controller

receives all the information from the 2 units after arranging the results they are displayed in the

computer and they can be afterwards submitted for more complex analysis such as Finite Element

Analysis and we can get the Stress-Strain Diagram

322 Strain Measurement Equipment

The equipment used in our research provides a four-channel measurement that means we can use up

to 4 strain gauges at a time to do our measurements and provides 3 different bridge arrangements as

shown in figure 3-3

(a) (b) (c)

Fig 3-3 Input Connections for Strain Indicator

Figure 3-3 (a) is the Quarter Bridge (b) is the Half Bridge and (c) is the Full Bridge and Transducers

For our study we used the Quarter Bridge and use the Strain Gauge values to decide the position of the

connecting wires The Strain indicator is shown in figure 3-4

Fig 3-4 Vishay Micro-Measurements Model P3 Strain Indicator and Recorder

44

Input Connections Tool Free eccentric lever release

4-channel input

Wire diameter16-28AWG

Bridge Configurations Quarter- Half- and Full Bridge

Bridge Impedance 60-2000Ω

Display 128 64 pixel FSTN positive gray LCD

Data Conversion AD Converter filter

Measurement Range Resolution Strain Range plusmn155mVV

Resolution plusmn00005mVV

Measurement Accuracy plusmn01 of reading plusmn3 counts

Gage Factor Control 0500-9900

Balance Control Software either manual or automatic

Bridge Excitation 15VDC nominal

Communication Interface USB Cable Included

Data Storage Removable Media Card

Shunt Calibration Across bridge completion resistors controlled

by software When Gage Factor=200

120Ω350Ω1000Ω

Analog Output Value 0 to 25V max

Ranges plusmn320 microε plusmn3200 microε plusmn32000 microε

Error 05 output voltage +5mV

Max Error 14 output voltage + 20mV

Update rate 480 samplessec

Output Load 2000Ω

Power Battery Two Alkaline D cells

Battery life 400 hours typ

USB 5V 100mA

Operational Environment Temperature 0-50

Humidity Up to 90 Non-condensing

Case Aluminum Alloy

Size and Weight 228times152times152(mm) 20(kg)

Table 3-2 Vishay Micro-Measurements Model P3 Strain Indicator and Recorder Specs

45

323 Strain Gauge

The strain gaugersquos main basic principle is to use a resistancersquos characteristics to measure the strain

The inside connections of the strain indicator are shown in figure 3-5

Fig 3-5 Inner Connections

As shown above this is a quarter-bridge connection We connect equal-length 3 wires to the 2

connections allowed by the strain gauge wire 1 and 3 can be used to cancel out the effects of temperature

to the resistance and because of the addition of wires 1 and 3 wire 2 can directly measure the experiment

results from the strain gauge and therefore the strain developed with no influence of temperature

If there were no two measuring leads then the relations will be

R 4 =R g +2R L

Where Rg is the Strain Gauge Value and RL is the wire resistance then

4

4

R

R=

Lg

g

RR

R

2

=

gL

gg

RR

RR

21

amp

4

4

R

R=

g

g

R

R(1- L)

Where L is the Signal Loss Factor and so

L =gL

gL

RR

RR

21

2

g

L

R

2R if

g

L

R

2Rltlt1

46

(Actual Value R g =120R L =08g

L

R

2Ris always much smaller than 1)

R 4 =R g +2R LR 2 =R 3 =rR gR 1 =R g 32 RR =0

V 0 =V 2)1( r

r

(

4

4

R

R-

1

1

R

R)

The first term describes loss attenuation effects second term describes loss of balancing capabilities

effects

V 0 =V 2)1( r

r

[

)2

(Lg

g

RR

R

+

T

Lg

g

RR

R

)

2( + T

Lg

L

RR

R

)

2

2( -(

g

g

R

R) T ]

The first term describes loss attenuation effects and loss of balancing capabilities effects the second

third and fourth terms describe the temperature effects on the wire

For the three-wire method we have

L =gL

gL

RR

RR

1

g

L

R

R if

g

L

R

Rltlt1

V 0 =V 2)1( r

r

[

)(Lg

g

RR

R

+

T

Lg

g

RR

R

)( + T

Lg

L

RR

R

)

2( -

T

Lg

g

RR

R

)( - T

Lg

L

RR

R

)

2( ]

V 0 = V2)1( r

r

)(

Lg

g

RR

R

In the last four terms inside parenthesis we can see the effects of temperature being cancelled out and the

effect on first term is not great so this is the reason why in our research we use three wires

47

324 Specimen Measurements

The tensile specimens used in this research are compliant of ASTM E8 Tensile parameters as shown

in figure 3-6

Fig 3-6 Tensile Specimen

Diameter

D(mm)

Gauge

Length

G(mm)

Smallest

Arc

Radius

R(mm)

Shortest

Area

A(mm)

Total

Length

L(mm)

Clamping

Area

Length

B(mm)

Clamping

Area

Diameter

C(mm)

Bar 125 02 625 01 gt10 gt75 ~ 145 ~ 35 20

Table 3-3 Specifications for Round Bar

33 Experiment Procedure

1 Attaching the Strain Gauge to the Tensile Specimen

(1) Prepare 1 ASTM E8 compliant tensile specimen round bar as shown in figure 3-7

(2) Prepare Strain Gauge as those described in table 3-4

(3) Prepare other consumables and adhesive agent such as epoxy adhesive or

cyanoacrylate adhesive as shown in figure 3-8

48

Fig 3-7 Actual Tensile Specimen

Fig 3-8 Other Materials Used (Such as Alcohol gauze transparent tape adhesive)

Gage Type

EA-06-120LZ-120E

Resistance in ohms at 24∘C

1200plusmn03

Gage Factor at 24∘C

2075plusmn05

Transverse Sensitivity at 24∘C

(+07plusmn02)

Table 3-4 Specifications for Strain Gauge

2 Attaching Strain Gauge

As shown in following figures we shall explain the attachment of the strain gauge

(1) Use sand paper and a rasp to clean thoroughly the surface where the strain gauge will be

attached to

49

(a)

(2) Use alcohol to wash the surface where the strain gauge will be attached and use gauze to rub

it off

(b)

(3) Find a clean surface and clean it with alcohol and gauze

(c)

(4) Place the strain gauge in the clean surface Use a piece of transparent tape on top of the strain

gauge after securely placed rip it off the surface carefully

50

(d)

(5) Use a piece of white paper to mark the place where the strain gauge will be attached and in

this way we can make sure that the strain gauge will be placed as horizontally and vertically

correct as possible

(e)

(6) In the place where we had our mark place the strain gauge

(f)

(7) Carefully lift one side of the tape and apply some of the adhesive agent to both the strain

gauge and specimenrsquos surface

(g)

51

(8) We need to make sure that the gauge and the specimen will be firmly attached so we gently

apply pressure with our thumb

(h)

(9) After the adhesive is fully dry we can carefully rip off the tape

(i)

(10) We need to do the whole process twice one for the horizontally placed strain gauge and one

for the vertically placed strain gauge

52

(j)

(11) We now proceed to solder the wires to the strain gauge

(k)

(12) After soldering we use a Volt Multimeter to measure that there is no contact between wires

If there is none then the specimen is ready for testing

(l)

(13) We now need to measure a 5cm distance and mark it to check and compare the elongation

before and after the tensile testing

(m)

53

Fig 3-9 Specimen-Strain Gauge Process

3 Tensile Test

(1) Enter the computer application that controls the tensile testing machine

(2) Turn on the tensile testing machine main switch

(3) Adjust the hydraulic pump to go back to its original position

(4) Bring the lowering motor down to a distance enough so as to attach the tensile specimen to the

system open the clamps and secure the specimen

(a)

(5) Connect all the necessary wires to the strain indicator equipment

54

(b)

(6) Start the ascending motor and wait for the expansion

(c)

Fig 3-10 Specimen-Tensile Testing Process

4 Start the Test

(1) Enter the software application and enter some variables needed for the experiment in the

specific screen

(2) Go back to the main screen and press the [測試] (measure) button to start the test and auto

recording in the software

(3) After the specimen breaks the mechanical device will automatically stop and ask the user to

enter the total displacement We take out the specimen from the testing machine and adjust the

machinersquos position back to its original position

(4) Save the results information

(5) Record the results from the strain indicator

34 Results

From this experiment we can get the Poissonrsquos Ratio Youngrsquos Modulus and Yield Strength etc and

because of the slippage phenomenon in the clamp at the moment of the test then the Elastic Limit will

display some yield phenomena So omit any undesirable results we just take the Yield portion of the

results as reference

In the process of the experiment the most important part to attend to is the attaching of the strain

gauge because the gaugersquos purpose is to measure the strain developed during the test and this strain

might be very small If the gaugersquos angle change during the test ie is not well attached this will affect

the accuracy of the measurements of Poissonrsquos ratio and Youngrsquos modulus

55

The materials provided by the manufacturer are SUM 23 and SUM 43 steel round bars and these two

types of materials have been through different heat treatment processes so they can be sub-divided

further into untreated material heat-treated material and black surface heat treated material for the two

materials with heat treatment the treatment process and finished are different In the end we only have

the mechanical properties that were calculated after our research of these materials

All of the specifications are identical to those shown in figure 3-6

341 SUM 23

Fig 3-11 SUM 23 Untreated Material

Number 7 10

Hardness(HRB) 74 75

Yield Stress (MPa) 448 440

Tensile Strength (MPa) 544 560

Poissonrsquos Ratio 029 027

Youngrsquos Modulus (GPa) 203 210

Cut-off Area Shrinking () 42 41

Elongation () 1125 1011

Table 3-5 Mechanical Properties of SUM 23 Untreated

56

Stress-Strain Diagram

(a)

(b)

57

Fig 3-12 Stress-Strain Diagrams for (a) 7 Round Bar and (b) 10 Round Bar

Cut-Off Area

(a)

(b)

Fig 3-13 Cut-Off Area of (a) 7 Round Bar and (b) 10 Round Bar

58

SUM 23 Nickel Round Bar

Fig 3-14 SUM 23 Nickel Material

Number 1 2 3 4

Hardness(HRB) 48 50 49 48

Yield Stress (MPa) 370 370 380 400

Tensile Strength (MPa) 455 451 450 450

Poissonrsquos Ratio 028 046 029 026

Youngrsquos Modulus (GPa) 243 303 246 206

Cut-off Area Shrinking () 803 803 726 601

Elongation () 566 65 602 647

Table 3-6 Mechanical Properties of SUM 23 Nickel

59

Stress-Strain Diagram

(a)

60

(b)

(c)

(d)

61

Fig 3-15 Stress-Strain Diagrams for (a) 1 Round Bar (b) 2 Round Bar (c) 3 Round Bar and (d)

4 Round Bar

Cut-Off Area

(a)

(b)

62

(c)

(d)

Fig 3-16 Cut-Off Area of (a) 1 Round Bar (b) 2 Round Bar (c) 3 Round Bar and (d) 4 Round

Bar

63

SUM 23 Black Surface Round Bar

Fig 3-17 SUM 23 Black Surface Material

Number 1 2 3

Hardness(HRB) 51 50 51

Yield Stress (MPa) 378 371 369

Tensile Strength (MPa) 467 465 464

Poissonrsquos Ratio 03 016 04

Youngrsquos Modulus (GPa) 215 266 266

Cut-off Area Shrinking () 986 94 848

Elongation () 748 805 761

Table 3-7 Mechanical Properties of SUM 23 Black Surface Material

64

Stress-Strain Diagram

(a)

(b)

65

(c)

Fig 3-18 Stress-Strain Diagrams for (a) 1 Round Bar 2 Round Bar and (c) 3 Round Bar

Cut-Off Surface

(a)

66

(b)

(c)

Fig 3-19 Cut-Off Surface of (a) 1 Round Bar 2 Round Bar and (c) 3 Round Bar

67

342 SUM 43

Fig 3-20 Untreated SUM 43 Untreated Material

Number 1 5

Hardness(HRB) 76 75

Yield Stress (MPa) 572 594

Tensile Strength (MPa) 743 785

Poissonrsquos Ratio 027 029

Youngrsquos Modulus (GPa) 200 202

Cut-off Area Shrinking () 338 2944

Elongation () 857 894

Table 3-8 Mechanical Properties of SUM 43 Untreated

68

Stress-Strain Diagrams

(a)

(b)

Fig 3-21 Stress-Strain Diagrams for SUM 43 (a) 1 Round Bar and (b) 5 Round Bar

69

Cut-Off Area

(a)

(b)

Fig 3-22 Cut-Off Area of SUM 43 (a) 1 Round Bar and (b) 5 Round Bar

70

SUM 43 Nickel Round Bar

Fig 3-23 SUM 43 Nickel Material

Number 4 5

Hardness(HRB) 51 50

Yield Stress (MPa) 1580 1544

Tensile Strength (MPa) 1639 1625

Poissonrsquos Ratio 03 028

Youngrsquos Modulus (GPa) 194 201

Cut-off Area Shrinking () 1697 137

Elongation () 376 265

Table 3-9 Mechanical Properties of SUM 43 Nickel

71

Stress-Strain Diagrams

(a)

(b)

Fig 3-24 Stress-Strain Diagrams for (a) 4 Round Bar and (b) 5 Round Bar

72

Cut-Off Area

(a)

(b)

Fig 3-25 Cut-Off Area of (a) 4 Round Bar and (b) 5 Round Bar

73

SUM 43 Black Surface Material

Fig 3-26 SUM 43 Black Surface Material

Number 3 5

Hardness(HRB) 56 56

Yield Stress (MPa) 1416 1361

Tensile Strength (MPa) 1591 1402

Poissonrsquos Ratio 029 031

Youngrsquos Modulus (GPa) 200 202

Cut-off Area Shrinking () 139 124

Elongation () 24 24

Table 3-10 Mechanical Properties of SUM 43 Black Surface Material

74

Stress-Strain Diagrams

0 2 4 6 8 10 12 14

-200

0

200

400

600

800

1000

1200

1400

1600

1800

應力 (MPa)

應變()

(a)

0 2 4 6 8 10

-200

0

200

400

600

800

1000

1200

1400

1600

應力

(MPa)

位移 ()

(b)

Fig 3-27 Stress-Strain Diagrams for (a) 3 Round Bar and (b) 5 Round Bar

(Note These curves were formulated using Visual Solutions Inc VisSim Software)

75

Cut-Off Area

(a)

(b)

Fig 3-28 Cut-Off Area of (a) 3 Round Bar and (b) 5 Round Bar

76

The force value (N) was retrieved from the Universal Testing Machine

The Poissonrsquos Ratio (ε) is calculated as

ε =

the values for the Poissonrsquos Ratio are in average around 0297

The Youngrsquos Modulus (E) is calculated as

E =

Where

Stress =

Cross-sectional Area =

where D is the Diameter

The value for D was in average around 1258 mm

The values shown by the computer because there is Slippage phenomena between the Clamp and the

specimen will not be taken into consideration for the elongation strain and Youngrsquos modulus and we will

refer to the values that we have meticulously calculated

77

Chapter 4 AR COATING IN DEPTH

41 Experimentrsquos Purpose and Principles

By means of a vacuum chamber and several other instruments we intend to apply Anti-Reflective

Coating using deposition process to a laser diode and in this way reduce its refraction so as to make it

lose less light in the process of amplification and we can control certain wavelengths we want produced

for certain desired applications in our case we are attempting to re-create a Bose-Einstein Condensate

An optimal BEC apparatus is shown in figure 4-1

Fig 4-1 BEC Apparatus

The main point of this experiment is to build a vacuum chamber system attach all the instrumentation

needed (Vacuum pump deposition meter and voltmeter) and use it to apply AR coating to a laser diode

After we have accomplished the AR coating other team will be in charge of designing the BEC apparatus

and use the results of our research

78

42 Experimentrsquos Equipment

421 Vacuum Chamber

For this research we designed a vacuum chamber whose main body is shown in figure 4-2 Its

dimensions are

Width 240 mm

Length 240 mm

Height 200 mm

Outer Diameter 4 in

Inner Diameter 15 in

Fig 4-2 Vacuum Chamber Main Body

The chamber is made up of 6 pass ways pass way A is the connection with the Laser Deposition

Equipment pass way B is the connection with the Turbo Pump and pass way C is for the connection with

the Deposition Source

A

C

B

79

Pass way C is for the deposition source as mentioned above This is a system where a thermal

resistance is heated by passing a high current through it which heats up a filament boat (made of tungsten)

where the material to be evaporated is place We control the temperature as such that the material will

evaporate and the heat will not cause the filament boat to crack

Because P = Isup2 R (where P is power I is current and R is resistance) to avoid the current to flow

where it is not desired we decided that the material for the Thermocouple shown in figure 4-3 should be

Copper ᴓ 63 mm We choose it that way because Copper has very good heat dissipation characteristics

and the resistance value is low It can reduce the value of the current enough to make the thermocouple to

create heat

Fig 4-3 Thermocouple

To the thermocouple we attach the tungsten filament boat We need to take notice of materials to be

used in this design because when using high current the tungsten filament boar will heat up and so the

material must be able to keep up with the heating potential of tungsten and has a low coefficient of heat

dissipation to avoid the tungsten to fail when heating up and therefore not evaporating Considering all

this we decide to use Stainless Steel

Because this clamp will be assembled inside the chamber after many revisions it was determined it

will have the shape shown in figure 4-4

Fig 4-4 Filament Boat Clamp Design

80

For the tungsten filament boat we bought the product from a distributor The dimensions are

Length 100 mm

Width 10 mm

Height 1 mm

Our thermocouple is 15 in but the pass way C is 4 in so we need to attach a Flange that connects

15in to 4in Because these specifications are quite difficult to achieve by Milling we had to use

electrical wire cutting

For the laser clamping system where the laser that is going to be AR coated will be placed will be

connected to pass way A the assembly is shown in figure 4-5 below

Fig 4-5 Cover Assembly

For this design we used an O-ring instead of a gasket so as to save time The design of the assembly

where the laser will be placed is shown in figure 4-6

Fig 4-6 Upper Cover Inner Assembly

D

E

F

81

Point D is the plate in the assembly where the laser diode will be fixed Because of the easy

processing we decide to use Aluminum and it is screwed to the top cover Point E is the connection for

the Quartz crystal resonator and it is designed in the same as point F in this way the results of the quartz

microbalance system will be more accurate in real time Point F is the final resting place for the laser

diode We use a Thor Labs Base with dimensions of ᴓ 9mm and ᴓ 56mm for two different size laser

diodes It just needs to be plugged in for easy installation

From figure 4-6 we know that the system needs signal system connections and because of the

change in temperature inside the chamber this could affect the functioning of the quartz microbalance so

we also need to install water tubes for cooling This is shown in figure 4-7 below

Fig 4-7 Diagram of Upper Cover Connections

In figure 4-8 we show the Feed through connections and their functions

Fig 4-8 Feed through Diagram

82

1 SQM-160 wire 5 Laser Connection 1 (Vin)

2 SQM-160 (G) 6 Laser Connection 2 (G)

3 K-Type-1 7 Laser Connection 3 (PD)

4 K-Type-2 8 Not In Use

The fully assembled chamber is shown in figure 4-9

Fig 4-9 Fully Assembled Chamber

422 Quartz Crystal Microbalance

For measuring the deposition on our target for coating we used the Inficon SQM-160 RateThickness

Monitor It is an easy to use instrument for measuring many types of thin-film coatings as shown in

figure 4-10

(a) Front Panel (b) Back Panel

Fig 4-10 Inficon SQM-160

83

Table 4-1 shows the technical specifications for this equipment

Number of sensors 2 Standard 4 additional optional

Sensor Frequency Range 40 MHz ~ 60 MHz

Reference Frequency Accuracy 002

Thickness Display Resolution 1 Aring

Thickness Resolution 015 Aring (Std) 0037 Aring (Hi Res)

Density of Stored Films 05-9999 gmcc

Tooling 10-399

Z-Factor 010-1000

Final Thickness 0000-9999k Aring

Measurement Period 15 to 2 sec

Simulation Mode Yes

Frequency Mode Yes

Rate Resolution 011 Arings

Dual Crystal Yes

Etch Mode Yes

Crystal Tooling 10-399

Crystal Fail Min Max 40 to 60 MHz 41 to 61 MHz

Power 100-120 200-240~plusmn10 nominal 20W

Operation Environment 0degC ~ 50degC

0 ~ 80 RH non-condensing

0 ~ 2000 meters

Class 1 Equipment

Pollution Degree 2

Rack Dimensions 885mm x 2127mm x 1969mm

Weight 27 kg

Table 4-1 Inficon SQM-160 RateThickness Monitor Specs

84

To the SQM-160 we need to connect an Oscillator We use the Sigma Instruments Remote Oscillator

Ser No 2 268 as shown in figure 4-11

Fig 4-11 Sigma Instruments Remote Oscillator

The connections diagram is shown in figure 4-12

Fig 4-12 SQM-160 Connections Diagram

85

423 Turbo Pump

For our experiments we used the Pfeiffer TCP 015 Electronic Drive Unit shown below in figure 4-13

Table 4-2 shows the technical specifications for this equipment

(a) Front Panel (b) Back Panel

Fig 4-13 Pfeiffer TCP 015 Electronic Drive

Connection Voltage (100V) 90-112

Mains Frequency 5060 Hz

Start-up Current 22 A

Nominal Frequency 1500 Hz

Rotation Speed 10V = 1500Hz plusmn2

Analog Output Current 10 V = 25 A plusmn 5

Rotation Speed Switchpoint 750 Hz

Works Setting 8 min

Permissible Ambient Temperature 0degC ~ 40degC

Dimensions Front Panel 1285mm x 1063mm

Insertion Length 227mm

Weight 27 Kg

Table 4-2 Pfeiffer TCP 015 Electronic Drive Specs

86

The connections diagram is shown in figure 4-14

Fig 4-14Connections Diagram for Pfeiffer TCP 015

To measure the pressure inside the chamber we use the Granville Phillips 375 Convectron Vacuum

Pressure Controller shown in figure 4-15

(a) Front Panel (b) Back Panel

Fig 4-15 Granville Phillips 375 Convectron

87

Its dimensions are shown in figure 4-16

Fig 4-16 Dimensions of Convectron

Table 4-3 shows the technical specifications for this equipment

Table 4-3 Granville Phillips 375 Convectron Vacuum Pressure Controller Specs

88

424 Multimeter

For our experiment we used the Keithley 2000 Digital Multimeter as shown in figure 4-17

(a) Front Panel (b) Back Panel

Fig 4-17 Keithley Model 2000 6-12-Digit Digital Multimeter

Its technical specifications are shown in table 4-4

Table 4-4 Keithley Model 2000 6-12-Digit Digital Multimeter Specs

89

43 Experiment Procedure

1 Connecting together the equipment and the chamber

(1) We first connect the resonator to the thickness monitor and connect the other side to the

chamber

(2) We now connect the flexible tubes to the turbo pump on one side and to the chamber on the

other

(3) We need to check that tubes are tightly connected to avoid any leaks in the vacuum pumping

process which will not allow us to get to our goal of Torr As shown in figure 4-18

(4) Connect the convectron to the system as shown in figure 4-19

Fig 4-18 checking for leaks using alcohol

Fig 4-19 Convectron attached to System

90

(5) Attach the clamps of the Multimeter to the bottom of the chamber as shown in figure 4-20

(6) Place the Quartz crystal in place

(7) Close tight vacuum chamber

(8) Connect all electrical appliances to power source

Fig 4-20 Multimeter Connections

2 Starting up the System

(1) We turn on all the devices as such Check all systems are ready to function Reset all values

that might be left over from previous tests

(2) Start the thickness monitor and set all values for this experiment In our case we got to testing

the system but not actual coating So we used the simulation mode of the thickness monitor as

shown in figure 4-21

Fig 4-21 Simulation Mode

91

(3) Start the turbo pump Make sure the lid on the vacuum chamber is tightly closed

(4) Start convectron and record initial pressure

(5) Start Multimeter and record initial current

3 Coating Process

(1) If we have the deposition material inside the filament boat the power source for the high

current must be started as well

(2) Record all initial values for thickness current pressure

(3) For an ideal experiment we need a thickness of around 101 nm a pressure of Torr and

a current of 300 A

44 Results

From previous experiments we have shown that we can turn a LED into a laser by means of AR

Coating In figure 4-22 shown below we can compare the actual results of a Diode before and after AR

coating From the blue line we can see that when the diode is at a current of 15mA its light will change

from LED to laser and if we look at the red line its critical current is around 30 to 35 mA

Fig 4-22 AR Coating Comparison for Laser Diodes

This means that the light emitted is not as strong as if the diode had been coated because inside the

chamber there must be some excitation first so the reflectivity of both sides inside the diode must be high

So because of the coating in one of the sides we have opened a door and let the light come out so the

critical current is risen as such and will be higher value than that of before the coating

92

In the following figures we can see the difference between before and after coating in a material The

thickness is around 1016 nm for this material

Fig 4-23 Before Coating

Fig 4-24 After Coating

93

Chapter 5 CONCLUSIONS AND RECOMMENDATIONS

51 Conclusions

For the first part of this independent study taking into consideration the data that came out of our

research and that sent by the provider we can say

1 SUM 23 after heat treatment will unexpectedly develop cracking in the middle of the tensile

testing process and suddenly break

2 Itrsquos possible that in the process of heat treatment to the SUM 23 material the treatment was not

uniform and this will create a pre-loaded moment force on one side that pushes on the other side

of the specimen resulting in material deformation

3 In the process of attaching the strain gauges to the materials it is very easy to make errors due to

poor adhesion or sudden removal in the tensile testing process

For our second part of the independent study the following can be made

1 At the beginning of this independent study we had no idea what Bose-Einstein Condensate was

or what was its purpose After much literature we finally comprehended the basic principles to

put into practice for our research

2 Our systemrsquos basic working principles and equipmentrsquos complexity are a little difficult to grasp

but hopefully we were able to understand enough of it

3 Theoretically from relation between the power and current we can know the advantages and

disadvantages of AR Coating

4 We were able to assemble the system and run test on its functions Even though we were able to

do this there is still much more work left to do with this system

52 Recommendations

For the Tensile Testing the following can be said

1 Ask the provider to check on the process of heat treatment on the SUM 23 material and give

them the information we have gathered through our test so they can correct for the mechanical

properties found if any change is needed

2 To avoid the problem of the inaccuracy of the poor adhesion of strain gauges we can attach

multiple strain gauges to the same one specimen so as to correlate data and improve our results

For the AR Coating the following can be said

1 We need to make sure that there are no physical defects on the main body of the chamber so as to

achieve maximum efficiency in the vacuum process If there was then the vacuum will arrive to

certain point and then start to decrease

2 It would be preferable to add some sort of visual aid that will allow the user to check the inside of

the chamber without actually opening it This will help us determine at what times we should

manipulate the current to better evaporate the substrate

94

REFERENCES

[1] A L Window Strain Gauge Technology Elsevier Applied Science London and New York 2nd

Edition 1992

[2] CC Perry and HR Lissner Strain Gauge Primer McGraw-Hill Book Co Inc New York 1955

[3] James W Dally William F Riley McGraw-Hill 1978

[4] University of Colorado Boulder BEC - What is it and where did the idea come from

httpwwwcoloradoeduphysics2000becwhat_is_ithtml

[5] Ultraslow Light amp Bose-Einstein Condensates Two-way Control with Coherent Light amp Atom

Fields Harvard Hau Lab Dr Lene Vestergaard Hau Optics amp Photonics News 16 1995

[6] The Art of Taming Light Ultra-slow and Stopped Light Harvard Hau Lab Dr Lene

Vestergaard Hau Europhysics News 2004

[7] Nonlinear Optics Shocking Superfluids Harvard Hau Lab Dr Lene Vestergaard Hau Nature

Physics 2007

[8] Model P3 Strain Indicator and Recorder Instruction Manual Vishay Micro-Measurements 2005

[9] Granville-Phillips Series 375 Convectron Vacuum Gauge Controller Instruction Manual Brooks

Automation 2008

[10] Effect of Film Thickness on the Validity of the Sauerbrey Equation for Hydrated Polyelectrolyte

Films Vogt Lin Wu White 2004

[11] Quartz Crystal Microbalance Study of DNA Immobilization and Hybridization for DNA Sensor

Development Chang Zhao 2008

[12] Installation of Strain Gages with SR-4 PrecoatAdhesive Vishay Micro-Measurements 2005

[13] Strain Gauge Measurement ndash A Tutorial National Instruments 1998

[14] Correlation between Vickers Hardness Number and Yield Stress of Cold-Formed Products

Yavuz Tekkaya

[15] httpsenwikipediaorg

Page 33: PC Hinge Materials Testing and AR Laser Diode Coating

33

Table 2-2 Z-Ratios for Different Materials

Table 2-2 Continued

34

Table 2-2 Continued

35

Table 2-2 Continued

36

Table 2-2 Continued

37

Table 2-2 Continued

38

Table 2-2 Continued

235 Vacuum Chamber System

Vacuum Evaporation is the process of depositing thin films of materials onto surfaces The technique

consists of pumping a vacuum chamber to pressures of less than torr and heating a material to

produce a flux of vapor in order to deposit the material onto a surface The material to be vaporized is

typically heated until its vapor pressure is high enough to produce a flux several Angstrom per second by

using an electrically resistive heater or bombardment by a high voltage beam The process was invented

by Henri Nestle in 1886 for food industry

In here the system has been pumped to a vacuum of Torr When a high current is passed

through the filament boat the filament boat is heated over the desired metal evaporation temperature and

so evaporation starts When the evaporation process is finished and the metal cools down crystals

condensate in the surface of the wafer From the weight of the evaporated material the distance between

the filament boat and the wafer we are able to calculate the deposition thickness and we can also use the

mass detector follower like the Quartz crystal resonator microbalance system In the process of

evaporation we usually use a board in between the filament boat and the wafer This is because before we

arrive to the desired evaporation temperature there will be some impurities that will be vaporized in the

controlled environment so we first use a small current and the board in between to get rid of those

impurities and this raises the purity of the deposition material

39

A vacuum evaporation system is shown in figure 2-24

Fig 2-24 Vacuum Evaporation System

Rough Vacuum 760 ~ 1 torr

Medium Vacuum 1 ~ torr

High Vacuum ~ torr

Ultra-High Vacuum Lower than torr

Table 2-3 Classification of Vacuum

For our study we need to use a Turbo Pump A regular turbo pump is shown in figure 2-25

Fig 2-25 Turbo Pump

For our research we used the Pfeiffer TCP 015 Electronic Drive Unit and Granville Phillips 375

Convectron shown below in figure 2-26

40

Fig 2-26 Control and Measurement Equipment

The electronic drive controls the turbo pump and the Convectron measures the pressure inside our

chamber The turbo pump is a type of vacuum pump used to maintain high vacuum Most turbo pumps

are centrifugal When we start the pumping we need to use a mechanical pump so as to decrease the

pressure inside the system from constant atmospheric pressure to torr and then the use dispersion

pump to continue the vacuum until we get to the desired pressure We need to notice though when we

start the dispersion pump we canrsquot turn off the mechanical pump and they both need to run together If

we need to turn off the pumping we first turn off the dispersion pump wait for it to completely stop and

then turn off the mechanical pump

Our completely assembled system is shown in figure 2-27 below

Fig 2-27 Complete System

41

Chapter 3 TENSILE TESTING IN DEPTH

31 Experimentrsquos Purpose and Principles

By means of Universal testing machine and Strain gauges we were able to observe discuss and

analyze the phenomena created when a specimen of certain material is manipulated under an external load

and determine the stress strain and deformation values later we can use the graphing methods of

stress-strain diagram to describe it

The main point of this experiment is that after the tensile specimen is tested use computer analysis

and the actual strain data and after statistical adjustment make the final results report (Tensile testing

experiment is in accordance with ASTM E8)

32 Experimentrsquos Equipment

321 Universal Testing Machine

For the materials testing experiment part of this research we use a Universal Testing Machine as

shown in figure 31 The maximum load it can apply is 100 Ton After the test specimen is secured on the

device with the use of instrumentation the load exerted and the effects of this become apparent on the

specimen and even the smallest of changes can be recorded For our research we used the Chun Yen

Testing Machines Co Ltd 100 Ton Micro Computer Universal Tensile Tester

Fig 31 Universal Testing Machine

42

Table 31 shows the specifications for this machine

Max Capacity 100 Ton

Accuracy plusmn1

Tension (mm) Max Space 1150mm

Grip for Rod 20-70mm

Ram Stroke 250mm

Effective Column Interval 940mm

Crosshead Speed 300mmmin

Testing Speed 0-50mmmin

Volume of Machine 1700times1000times3350mm(LtimesWtimesH)

Volume of Control Panel 1000times800times1500mm(LtimesWtimesH)

Weight 8000kg

Power 3∮220V 20A

Computer AMD K6-2-350

OS Windows XP

Screen 15rdquo CRT

Table 3-1 Chun Yen Testing Machine Specs Table

The connections diagram is shown in figure 3-2

Fig 3-2 Diagram for System Connections

43

When the test specimen is placed when the external force is applied the Load Cell can measure the

size of the applied force and the Encoder measures the expansion rate of change The Local Controller

receives all the information from the 2 units after arranging the results they are displayed in the

computer and they can be afterwards submitted for more complex analysis such as Finite Element

Analysis and we can get the Stress-Strain Diagram

322 Strain Measurement Equipment

The equipment used in our research provides a four-channel measurement that means we can use up

to 4 strain gauges at a time to do our measurements and provides 3 different bridge arrangements as

shown in figure 3-3

(a) (b) (c)

Fig 3-3 Input Connections for Strain Indicator

Figure 3-3 (a) is the Quarter Bridge (b) is the Half Bridge and (c) is the Full Bridge and Transducers

For our study we used the Quarter Bridge and use the Strain Gauge values to decide the position of the

connecting wires The Strain indicator is shown in figure 3-4

Fig 3-4 Vishay Micro-Measurements Model P3 Strain Indicator and Recorder

44

Input Connections Tool Free eccentric lever release

4-channel input

Wire diameter16-28AWG

Bridge Configurations Quarter- Half- and Full Bridge

Bridge Impedance 60-2000Ω

Display 128 64 pixel FSTN positive gray LCD

Data Conversion AD Converter filter

Measurement Range Resolution Strain Range plusmn155mVV

Resolution plusmn00005mVV

Measurement Accuracy plusmn01 of reading plusmn3 counts

Gage Factor Control 0500-9900

Balance Control Software either manual or automatic

Bridge Excitation 15VDC nominal

Communication Interface USB Cable Included

Data Storage Removable Media Card

Shunt Calibration Across bridge completion resistors controlled

by software When Gage Factor=200

120Ω350Ω1000Ω

Analog Output Value 0 to 25V max

Ranges plusmn320 microε plusmn3200 microε plusmn32000 microε

Error 05 output voltage +5mV

Max Error 14 output voltage + 20mV

Update rate 480 samplessec

Output Load 2000Ω

Power Battery Two Alkaline D cells

Battery life 400 hours typ

USB 5V 100mA

Operational Environment Temperature 0-50

Humidity Up to 90 Non-condensing

Case Aluminum Alloy

Size and Weight 228times152times152(mm) 20(kg)

Table 3-2 Vishay Micro-Measurements Model P3 Strain Indicator and Recorder Specs

45

323 Strain Gauge

The strain gaugersquos main basic principle is to use a resistancersquos characteristics to measure the strain

The inside connections of the strain indicator are shown in figure 3-5

Fig 3-5 Inner Connections

As shown above this is a quarter-bridge connection We connect equal-length 3 wires to the 2

connections allowed by the strain gauge wire 1 and 3 can be used to cancel out the effects of temperature

to the resistance and because of the addition of wires 1 and 3 wire 2 can directly measure the experiment

results from the strain gauge and therefore the strain developed with no influence of temperature

If there were no two measuring leads then the relations will be

R 4 =R g +2R L

Where Rg is the Strain Gauge Value and RL is the wire resistance then

4

4

R

R=

Lg

g

RR

R

2

=

gL

gg

RR

RR

21

amp

4

4

R

R=

g

g

R

R(1- L)

Where L is the Signal Loss Factor and so

L =gL

gL

RR

RR

21

2

g

L

R

2R if

g

L

R

2Rltlt1

46

(Actual Value R g =120R L =08g

L

R

2Ris always much smaller than 1)

R 4 =R g +2R LR 2 =R 3 =rR gR 1 =R g 32 RR =0

V 0 =V 2)1( r

r

(

4

4

R

R-

1

1

R

R)

The first term describes loss attenuation effects second term describes loss of balancing capabilities

effects

V 0 =V 2)1( r

r

[

)2

(Lg

g

RR

R

+

T

Lg

g

RR

R

)

2( + T

Lg

L

RR

R

)

2

2( -(

g

g

R

R) T ]

The first term describes loss attenuation effects and loss of balancing capabilities effects the second

third and fourth terms describe the temperature effects on the wire

For the three-wire method we have

L =gL

gL

RR

RR

1

g

L

R

R if

g

L

R

Rltlt1

V 0 =V 2)1( r

r

[

)(Lg

g

RR

R

+

T

Lg

g

RR

R

)( + T

Lg

L

RR

R

)

2( -

T

Lg

g

RR

R

)( - T

Lg

L

RR

R

)

2( ]

V 0 = V2)1( r

r

)(

Lg

g

RR

R

In the last four terms inside parenthesis we can see the effects of temperature being cancelled out and the

effect on first term is not great so this is the reason why in our research we use three wires

47

324 Specimen Measurements

The tensile specimens used in this research are compliant of ASTM E8 Tensile parameters as shown

in figure 3-6

Fig 3-6 Tensile Specimen

Diameter

D(mm)

Gauge

Length

G(mm)

Smallest

Arc

Radius

R(mm)

Shortest

Area

A(mm)

Total

Length

L(mm)

Clamping

Area

Length

B(mm)

Clamping

Area

Diameter

C(mm)

Bar 125 02 625 01 gt10 gt75 ~ 145 ~ 35 20

Table 3-3 Specifications for Round Bar

33 Experiment Procedure

1 Attaching the Strain Gauge to the Tensile Specimen

(1) Prepare 1 ASTM E8 compliant tensile specimen round bar as shown in figure 3-7

(2) Prepare Strain Gauge as those described in table 3-4

(3) Prepare other consumables and adhesive agent such as epoxy adhesive or

cyanoacrylate adhesive as shown in figure 3-8

48

Fig 3-7 Actual Tensile Specimen

Fig 3-8 Other Materials Used (Such as Alcohol gauze transparent tape adhesive)

Gage Type

EA-06-120LZ-120E

Resistance in ohms at 24∘C

1200plusmn03

Gage Factor at 24∘C

2075plusmn05

Transverse Sensitivity at 24∘C

(+07plusmn02)

Table 3-4 Specifications for Strain Gauge

2 Attaching Strain Gauge

As shown in following figures we shall explain the attachment of the strain gauge

(1) Use sand paper and a rasp to clean thoroughly the surface where the strain gauge will be

attached to

49

(a)

(2) Use alcohol to wash the surface where the strain gauge will be attached and use gauze to rub

it off

(b)

(3) Find a clean surface and clean it with alcohol and gauze

(c)

(4) Place the strain gauge in the clean surface Use a piece of transparent tape on top of the strain

gauge after securely placed rip it off the surface carefully

50

(d)

(5) Use a piece of white paper to mark the place where the strain gauge will be attached and in

this way we can make sure that the strain gauge will be placed as horizontally and vertically

correct as possible

(e)

(6) In the place where we had our mark place the strain gauge

(f)

(7) Carefully lift one side of the tape and apply some of the adhesive agent to both the strain

gauge and specimenrsquos surface

(g)

51

(8) We need to make sure that the gauge and the specimen will be firmly attached so we gently

apply pressure with our thumb

(h)

(9) After the adhesive is fully dry we can carefully rip off the tape

(i)

(10) We need to do the whole process twice one for the horizontally placed strain gauge and one

for the vertically placed strain gauge

52

(j)

(11) We now proceed to solder the wires to the strain gauge

(k)

(12) After soldering we use a Volt Multimeter to measure that there is no contact between wires

If there is none then the specimen is ready for testing

(l)

(13) We now need to measure a 5cm distance and mark it to check and compare the elongation

before and after the tensile testing

(m)

53

Fig 3-9 Specimen-Strain Gauge Process

3 Tensile Test

(1) Enter the computer application that controls the tensile testing machine

(2) Turn on the tensile testing machine main switch

(3) Adjust the hydraulic pump to go back to its original position

(4) Bring the lowering motor down to a distance enough so as to attach the tensile specimen to the

system open the clamps and secure the specimen

(a)

(5) Connect all the necessary wires to the strain indicator equipment

54

(b)

(6) Start the ascending motor and wait for the expansion

(c)

Fig 3-10 Specimen-Tensile Testing Process

4 Start the Test

(1) Enter the software application and enter some variables needed for the experiment in the

specific screen

(2) Go back to the main screen and press the [測試] (measure) button to start the test and auto

recording in the software

(3) After the specimen breaks the mechanical device will automatically stop and ask the user to

enter the total displacement We take out the specimen from the testing machine and adjust the

machinersquos position back to its original position

(4) Save the results information

(5) Record the results from the strain indicator

34 Results

From this experiment we can get the Poissonrsquos Ratio Youngrsquos Modulus and Yield Strength etc and

because of the slippage phenomenon in the clamp at the moment of the test then the Elastic Limit will

display some yield phenomena So omit any undesirable results we just take the Yield portion of the

results as reference

In the process of the experiment the most important part to attend to is the attaching of the strain

gauge because the gaugersquos purpose is to measure the strain developed during the test and this strain

might be very small If the gaugersquos angle change during the test ie is not well attached this will affect

the accuracy of the measurements of Poissonrsquos ratio and Youngrsquos modulus

55

The materials provided by the manufacturer are SUM 23 and SUM 43 steel round bars and these two

types of materials have been through different heat treatment processes so they can be sub-divided

further into untreated material heat-treated material and black surface heat treated material for the two

materials with heat treatment the treatment process and finished are different In the end we only have

the mechanical properties that were calculated after our research of these materials

All of the specifications are identical to those shown in figure 3-6

341 SUM 23

Fig 3-11 SUM 23 Untreated Material

Number 7 10

Hardness(HRB) 74 75

Yield Stress (MPa) 448 440

Tensile Strength (MPa) 544 560

Poissonrsquos Ratio 029 027

Youngrsquos Modulus (GPa) 203 210

Cut-off Area Shrinking () 42 41

Elongation () 1125 1011

Table 3-5 Mechanical Properties of SUM 23 Untreated

56

Stress-Strain Diagram

(a)

(b)

57

Fig 3-12 Stress-Strain Diagrams for (a) 7 Round Bar and (b) 10 Round Bar

Cut-Off Area

(a)

(b)

Fig 3-13 Cut-Off Area of (a) 7 Round Bar and (b) 10 Round Bar

58

SUM 23 Nickel Round Bar

Fig 3-14 SUM 23 Nickel Material

Number 1 2 3 4

Hardness(HRB) 48 50 49 48

Yield Stress (MPa) 370 370 380 400

Tensile Strength (MPa) 455 451 450 450

Poissonrsquos Ratio 028 046 029 026

Youngrsquos Modulus (GPa) 243 303 246 206

Cut-off Area Shrinking () 803 803 726 601

Elongation () 566 65 602 647

Table 3-6 Mechanical Properties of SUM 23 Nickel

59

Stress-Strain Diagram

(a)

60

(b)

(c)

(d)

61

Fig 3-15 Stress-Strain Diagrams for (a) 1 Round Bar (b) 2 Round Bar (c) 3 Round Bar and (d)

4 Round Bar

Cut-Off Area

(a)

(b)

62

(c)

(d)

Fig 3-16 Cut-Off Area of (a) 1 Round Bar (b) 2 Round Bar (c) 3 Round Bar and (d) 4 Round

Bar

63

SUM 23 Black Surface Round Bar

Fig 3-17 SUM 23 Black Surface Material

Number 1 2 3

Hardness(HRB) 51 50 51

Yield Stress (MPa) 378 371 369

Tensile Strength (MPa) 467 465 464

Poissonrsquos Ratio 03 016 04

Youngrsquos Modulus (GPa) 215 266 266

Cut-off Area Shrinking () 986 94 848

Elongation () 748 805 761

Table 3-7 Mechanical Properties of SUM 23 Black Surface Material

64

Stress-Strain Diagram

(a)

(b)

65

(c)

Fig 3-18 Stress-Strain Diagrams for (a) 1 Round Bar 2 Round Bar and (c) 3 Round Bar

Cut-Off Surface

(a)

66

(b)

(c)

Fig 3-19 Cut-Off Surface of (a) 1 Round Bar 2 Round Bar and (c) 3 Round Bar

67

342 SUM 43

Fig 3-20 Untreated SUM 43 Untreated Material

Number 1 5

Hardness(HRB) 76 75

Yield Stress (MPa) 572 594

Tensile Strength (MPa) 743 785

Poissonrsquos Ratio 027 029

Youngrsquos Modulus (GPa) 200 202

Cut-off Area Shrinking () 338 2944

Elongation () 857 894

Table 3-8 Mechanical Properties of SUM 43 Untreated

68

Stress-Strain Diagrams

(a)

(b)

Fig 3-21 Stress-Strain Diagrams for SUM 43 (a) 1 Round Bar and (b) 5 Round Bar

69

Cut-Off Area

(a)

(b)

Fig 3-22 Cut-Off Area of SUM 43 (a) 1 Round Bar and (b) 5 Round Bar

70

SUM 43 Nickel Round Bar

Fig 3-23 SUM 43 Nickel Material

Number 4 5

Hardness(HRB) 51 50

Yield Stress (MPa) 1580 1544

Tensile Strength (MPa) 1639 1625

Poissonrsquos Ratio 03 028

Youngrsquos Modulus (GPa) 194 201

Cut-off Area Shrinking () 1697 137

Elongation () 376 265

Table 3-9 Mechanical Properties of SUM 43 Nickel

71

Stress-Strain Diagrams

(a)

(b)

Fig 3-24 Stress-Strain Diagrams for (a) 4 Round Bar and (b) 5 Round Bar

72

Cut-Off Area

(a)

(b)

Fig 3-25 Cut-Off Area of (a) 4 Round Bar and (b) 5 Round Bar

73

SUM 43 Black Surface Material

Fig 3-26 SUM 43 Black Surface Material

Number 3 5

Hardness(HRB) 56 56

Yield Stress (MPa) 1416 1361

Tensile Strength (MPa) 1591 1402

Poissonrsquos Ratio 029 031

Youngrsquos Modulus (GPa) 200 202

Cut-off Area Shrinking () 139 124

Elongation () 24 24

Table 3-10 Mechanical Properties of SUM 43 Black Surface Material

74

Stress-Strain Diagrams

0 2 4 6 8 10 12 14

-200

0

200

400

600

800

1000

1200

1400

1600

1800

應力 (MPa)

應變()

(a)

0 2 4 6 8 10

-200

0

200

400

600

800

1000

1200

1400

1600

應力

(MPa)

位移 ()

(b)

Fig 3-27 Stress-Strain Diagrams for (a) 3 Round Bar and (b) 5 Round Bar

(Note These curves were formulated using Visual Solutions Inc VisSim Software)

75

Cut-Off Area

(a)

(b)

Fig 3-28 Cut-Off Area of (a) 3 Round Bar and (b) 5 Round Bar

76

The force value (N) was retrieved from the Universal Testing Machine

The Poissonrsquos Ratio (ε) is calculated as

ε =

the values for the Poissonrsquos Ratio are in average around 0297

The Youngrsquos Modulus (E) is calculated as

E =

Where

Stress =

Cross-sectional Area =

where D is the Diameter

The value for D was in average around 1258 mm

The values shown by the computer because there is Slippage phenomena between the Clamp and the

specimen will not be taken into consideration for the elongation strain and Youngrsquos modulus and we will

refer to the values that we have meticulously calculated

77

Chapter 4 AR COATING IN DEPTH

41 Experimentrsquos Purpose and Principles

By means of a vacuum chamber and several other instruments we intend to apply Anti-Reflective

Coating using deposition process to a laser diode and in this way reduce its refraction so as to make it

lose less light in the process of amplification and we can control certain wavelengths we want produced

for certain desired applications in our case we are attempting to re-create a Bose-Einstein Condensate

An optimal BEC apparatus is shown in figure 4-1

Fig 4-1 BEC Apparatus

The main point of this experiment is to build a vacuum chamber system attach all the instrumentation

needed (Vacuum pump deposition meter and voltmeter) and use it to apply AR coating to a laser diode

After we have accomplished the AR coating other team will be in charge of designing the BEC apparatus

and use the results of our research

78

42 Experimentrsquos Equipment

421 Vacuum Chamber

For this research we designed a vacuum chamber whose main body is shown in figure 4-2 Its

dimensions are

Width 240 mm

Length 240 mm

Height 200 mm

Outer Diameter 4 in

Inner Diameter 15 in

Fig 4-2 Vacuum Chamber Main Body

The chamber is made up of 6 pass ways pass way A is the connection with the Laser Deposition

Equipment pass way B is the connection with the Turbo Pump and pass way C is for the connection with

the Deposition Source

A

C

B

79

Pass way C is for the deposition source as mentioned above This is a system where a thermal

resistance is heated by passing a high current through it which heats up a filament boat (made of tungsten)

where the material to be evaporated is place We control the temperature as such that the material will

evaporate and the heat will not cause the filament boat to crack

Because P = Isup2 R (where P is power I is current and R is resistance) to avoid the current to flow

where it is not desired we decided that the material for the Thermocouple shown in figure 4-3 should be

Copper ᴓ 63 mm We choose it that way because Copper has very good heat dissipation characteristics

and the resistance value is low It can reduce the value of the current enough to make the thermocouple to

create heat

Fig 4-3 Thermocouple

To the thermocouple we attach the tungsten filament boat We need to take notice of materials to be

used in this design because when using high current the tungsten filament boar will heat up and so the

material must be able to keep up with the heating potential of tungsten and has a low coefficient of heat

dissipation to avoid the tungsten to fail when heating up and therefore not evaporating Considering all

this we decide to use Stainless Steel

Because this clamp will be assembled inside the chamber after many revisions it was determined it

will have the shape shown in figure 4-4

Fig 4-4 Filament Boat Clamp Design

80

For the tungsten filament boat we bought the product from a distributor The dimensions are

Length 100 mm

Width 10 mm

Height 1 mm

Our thermocouple is 15 in but the pass way C is 4 in so we need to attach a Flange that connects

15in to 4in Because these specifications are quite difficult to achieve by Milling we had to use

electrical wire cutting

For the laser clamping system where the laser that is going to be AR coated will be placed will be

connected to pass way A the assembly is shown in figure 4-5 below

Fig 4-5 Cover Assembly

For this design we used an O-ring instead of a gasket so as to save time The design of the assembly

where the laser will be placed is shown in figure 4-6

Fig 4-6 Upper Cover Inner Assembly

D

E

F

81

Point D is the plate in the assembly where the laser diode will be fixed Because of the easy

processing we decide to use Aluminum and it is screwed to the top cover Point E is the connection for

the Quartz crystal resonator and it is designed in the same as point F in this way the results of the quartz

microbalance system will be more accurate in real time Point F is the final resting place for the laser

diode We use a Thor Labs Base with dimensions of ᴓ 9mm and ᴓ 56mm for two different size laser

diodes It just needs to be plugged in for easy installation

From figure 4-6 we know that the system needs signal system connections and because of the

change in temperature inside the chamber this could affect the functioning of the quartz microbalance so

we also need to install water tubes for cooling This is shown in figure 4-7 below

Fig 4-7 Diagram of Upper Cover Connections

In figure 4-8 we show the Feed through connections and their functions

Fig 4-8 Feed through Diagram

82

1 SQM-160 wire 5 Laser Connection 1 (Vin)

2 SQM-160 (G) 6 Laser Connection 2 (G)

3 K-Type-1 7 Laser Connection 3 (PD)

4 K-Type-2 8 Not In Use

The fully assembled chamber is shown in figure 4-9

Fig 4-9 Fully Assembled Chamber

422 Quartz Crystal Microbalance

For measuring the deposition on our target for coating we used the Inficon SQM-160 RateThickness

Monitor It is an easy to use instrument for measuring many types of thin-film coatings as shown in

figure 4-10

(a) Front Panel (b) Back Panel

Fig 4-10 Inficon SQM-160

83

Table 4-1 shows the technical specifications for this equipment

Number of sensors 2 Standard 4 additional optional

Sensor Frequency Range 40 MHz ~ 60 MHz

Reference Frequency Accuracy 002

Thickness Display Resolution 1 Aring

Thickness Resolution 015 Aring (Std) 0037 Aring (Hi Res)

Density of Stored Films 05-9999 gmcc

Tooling 10-399

Z-Factor 010-1000

Final Thickness 0000-9999k Aring

Measurement Period 15 to 2 sec

Simulation Mode Yes

Frequency Mode Yes

Rate Resolution 011 Arings

Dual Crystal Yes

Etch Mode Yes

Crystal Tooling 10-399

Crystal Fail Min Max 40 to 60 MHz 41 to 61 MHz

Power 100-120 200-240~plusmn10 nominal 20W

Operation Environment 0degC ~ 50degC

0 ~ 80 RH non-condensing

0 ~ 2000 meters

Class 1 Equipment

Pollution Degree 2

Rack Dimensions 885mm x 2127mm x 1969mm

Weight 27 kg

Table 4-1 Inficon SQM-160 RateThickness Monitor Specs

84

To the SQM-160 we need to connect an Oscillator We use the Sigma Instruments Remote Oscillator

Ser No 2 268 as shown in figure 4-11

Fig 4-11 Sigma Instruments Remote Oscillator

The connections diagram is shown in figure 4-12

Fig 4-12 SQM-160 Connections Diagram

85

423 Turbo Pump

For our experiments we used the Pfeiffer TCP 015 Electronic Drive Unit shown below in figure 4-13

Table 4-2 shows the technical specifications for this equipment

(a) Front Panel (b) Back Panel

Fig 4-13 Pfeiffer TCP 015 Electronic Drive

Connection Voltage (100V) 90-112

Mains Frequency 5060 Hz

Start-up Current 22 A

Nominal Frequency 1500 Hz

Rotation Speed 10V = 1500Hz plusmn2

Analog Output Current 10 V = 25 A plusmn 5

Rotation Speed Switchpoint 750 Hz

Works Setting 8 min

Permissible Ambient Temperature 0degC ~ 40degC

Dimensions Front Panel 1285mm x 1063mm

Insertion Length 227mm

Weight 27 Kg

Table 4-2 Pfeiffer TCP 015 Electronic Drive Specs

86

The connections diagram is shown in figure 4-14

Fig 4-14Connections Diagram for Pfeiffer TCP 015

To measure the pressure inside the chamber we use the Granville Phillips 375 Convectron Vacuum

Pressure Controller shown in figure 4-15

(a) Front Panel (b) Back Panel

Fig 4-15 Granville Phillips 375 Convectron

87

Its dimensions are shown in figure 4-16

Fig 4-16 Dimensions of Convectron

Table 4-3 shows the technical specifications for this equipment

Table 4-3 Granville Phillips 375 Convectron Vacuum Pressure Controller Specs

88

424 Multimeter

For our experiment we used the Keithley 2000 Digital Multimeter as shown in figure 4-17

(a) Front Panel (b) Back Panel

Fig 4-17 Keithley Model 2000 6-12-Digit Digital Multimeter

Its technical specifications are shown in table 4-4

Table 4-4 Keithley Model 2000 6-12-Digit Digital Multimeter Specs

89

43 Experiment Procedure

1 Connecting together the equipment and the chamber

(1) We first connect the resonator to the thickness monitor and connect the other side to the

chamber

(2) We now connect the flexible tubes to the turbo pump on one side and to the chamber on the

other

(3) We need to check that tubes are tightly connected to avoid any leaks in the vacuum pumping

process which will not allow us to get to our goal of Torr As shown in figure 4-18

(4) Connect the convectron to the system as shown in figure 4-19

Fig 4-18 checking for leaks using alcohol

Fig 4-19 Convectron attached to System

90

(5) Attach the clamps of the Multimeter to the bottom of the chamber as shown in figure 4-20

(6) Place the Quartz crystal in place

(7) Close tight vacuum chamber

(8) Connect all electrical appliances to power source

Fig 4-20 Multimeter Connections

2 Starting up the System

(1) We turn on all the devices as such Check all systems are ready to function Reset all values

that might be left over from previous tests

(2) Start the thickness monitor and set all values for this experiment In our case we got to testing

the system but not actual coating So we used the simulation mode of the thickness monitor as

shown in figure 4-21

Fig 4-21 Simulation Mode

91

(3) Start the turbo pump Make sure the lid on the vacuum chamber is tightly closed

(4) Start convectron and record initial pressure

(5) Start Multimeter and record initial current

3 Coating Process

(1) If we have the deposition material inside the filament boat the power source for the high

current must be started as well

(2) Record all initial values for thickness current pressure

(3) For an ideal experiment we need a thickness of around 101 nm a pressure of Torr and

a current of 300 A

44 Results

From previous experiments we have shown that we can turn a LED into a laser by means of AR

Coating In figure 4-22 shown below we can compare the actual results of a Diode before and after AR

coating From the blue line we can see that when the diode is at a current of 15mA its light will change

from LED to laser and if we look at the red line its critical current is around 30 to 35 mA

Fig 4-22 AR Coating Comparison for Laser Diodes

This means that the light emitted is not as strong as if the diode had been coated because inside the

chamber there must be some excitation first so the reflectivity of both sides inside the diode must be high

So because of the coating in one of the sides we have opened a door and let the light come out so the

critical current is risen as such and will be higher value than that of before the coating

92

In the following figures we can see the difference between before and after coating in a material The

thickness is around 1016 nm for this material

Fig 4-23 Before Coating

Fig 4-24 After Coating

93

Chapter 5 CONCLUSIONS AND RECOMMENDATIONS

51 Conclusions

For the first part of this independent study taking into consideration the data that came out of our

research and that sent by the provider we can say

1 SUM 23 after heat treatment will unexpectedly develop cracking in the middle of the tensile

testing process and suddenly break

2 Itrsquos possible that in the process of heat treatment to the SUM 23 material the treatment was not

uniform and this will create a pre-loaded moment force on one side that pushes on the other side

of the specimen resulting in material deformation

3 In the process of attaching the strain gauges to the materials it is very easy to make errors due to

poor adhesion or sudden removal in the tensile testing process

For our second part of the independent study the following can be made

1 At the beginning of this independent study we had no idea what Bose-Einstein Condensate was

or what was its purpose After much literature we finally comprehended the basic principles to

put into practice for our research

2 Our systemrsquos basic working principles and equipmentrsquos complexity are a little difficult to grasp

but hopefully we were able to understand enough of it

3 Theoretically from relation between the power and current we can know the advantages and

disadvantages of AR Coating

4 We were able to assemble the system and run test on its functions Even though we were able to

do this there is still much more work left to do with this system

52 Recommendations

For the Tensile Testing the following can be said

1 Ask the provider to check on the process of heat treatment on the SUM 23 material and give

them the information we have gathered through our test so they can correct for the mechanical

properties found if any change is needed

2 To avoid the problem of the inaccuracy of the poor adhesion of strain gauges we can attach

multiple strain gauges to the same one specimen so as to correlate data and improve our results

For the AR Coating the following can be said

1 We need to make sure that there are no physical defects on the main body of the chamber so as to

achieve maximum efficiency in the vacuum process If there was then the vacuum will arrive to

certain point and then start to decrease

2 It would be preferable to add some sort of visual aid that will allow the user to check the inside of

the chamber without actually opening it This will help us determine at what times we should

manipulate the current to better evaporate the substrate

94

REFERENCES

[1] A L Window Strain Gauge Technology Elsevier Applied Science London and New York 2nd

Edition 1992

[2] CC Perry and HR Lissner Strain Gauge Primer McGraw-Hill Book Co Inc New York 1955

[3] James W Dally William F Riley McGraw-Hill 1978

[4] University of Colorado Boulder BEC - What is it and where did the idea come from

httpwwwcoloradoeduphysics2000becwhat_is_ithtml

[5] Ultraslow Light amp Bose-Einstein Condensates Two-way Control with Coherent Light amp Atom

Fields Harvard Hau Lab Dr Lene Vestergaard Hau Optics amp Photonics News 16 1995

[6] The Art of Taming Light Ultra-slow and Stopped Light Harvard Hau Lab Dr Lene

Vestergaard Hau Europhysics News 2004

[7] Nonlinear Optics Shocking Superfluids Harvard Hau Lab Dr Lene Vestergaard Hau Nature

Physics 2007

[8] Model P3 Strain Indicator and Recorder Instruction Manual Vishay Micro-Measurements 2005

[9] Granville-Phillips Series 375 Convectron Vacuum Gauge Controller Instruction Manual Brooks

Automation 2008

[10] Effect of Film Thickness on the Validity of the Sauerbrey Equation for Hydrated Polyelectrolyte

Films Vogt Lin Wu White 2004

[11] Quartz Crystal Microbalance Study of DNA Immobilization and Hybridization for DNA Sensor

Development Chang Zhao 2008

[12] Installation of Strain Gages with SR-4 PrecoatAdhesive Vishay Micro-Measurements 2005

[13] Strain Gauge Measurement ndash A Tutorial National Instruments 1998

[14] Correlation between Vickers Hardness Number and Yield Stress of Cold-Formed Products

Yavuz Tekkaya

[15] httpsenwikipediaorg

Page 34: PC Hinge Materials Testing and AR Laser Diode Coating

34

Table 2-2 Continued

35

Table 2-2 Continued

36

Table 2-2 Continued

37

Table 2-2 Continued

38

Table 2-2 Continued

235 Vacuum Chamber System

Vacuum Evaporation is the process of depositing thin films of materials onto surfaces The technique

consists of pumping a vacuum chamber to pressures of less than torr and heating a material to

produce a flux of vapor in order to deposit the material onto a surface The material to be vaporized is

typically heated until its vapor pressure is high enough to produce a flux several Angstrom per second by

using an electrically resistive heater or bombardment by a high voltage beam The process was invented

by Henri Nestle in 1886 for food industry

In here the system has been pumped to a vacuum of Torr When a high current is passed

through the filament boat the filament boat is heated over the desired metal evaporation temperature and

so evaporation starts When the evaporation process is finished and the metal cools down crystals

condensate in the surface of the wafer From the weight of the evaporated material the distance between

the filament boat and the wafer we are able to calculate the deposition thickness and we can also use the

mass detector follower like the Quartz crystal resonator microbalance system In the process of

evaporation we usually use a board in between the filament boat and the wafer This is because before we

arrive to the desired evaporation temperature there will be some impurities that will be vaporized in the

controlled environment so we first use a small current and the board in between to get rid of those

impurities and this raises the purity of the deposition material

39

A vacuum evaporation system is shown in figure 2-24

Fig 2-24 Vacuum Evaporation System

Rough Vacuum 760 ~ 1 torr

Medium Vacuum 1 ~ torr

High Vacuum ~ torr

Ultra-High Vacuum Lower than torr

Table 2-3 Classification of Vacuum

For our study we need to use a Turbo Pump A regular turbo pump is shown in figure 2-25

Fig 2-25 Turbo Pump

For our research we used the Pfeiffer TCP 015 Electronic Drive Unit and Granville Phillips 375

Convectron shown below in figure 2-26

40

Fig 2-26 Control and Measurement Equipment

The electronic drive controls the turbo pump and the Convectron measures the pressure inside our

chamber The turbo pump is a type of vacuum pump used to maintain high vacuum Most turbo pumps

are centrifugal When we start the pumping we need to use a mechanical pump so as to decrease the

pressure inside the system from constant atmospheric pressure to torr and then the use dispersion

pump to continue the vacuum until we get to the desired pressure We need to notice though when we

start the dispersion pump we canrsquot turn off the mechanical pump and they both need to run together If

we need to turn off the pumping we first turn off the dispersion pump wait for it to completely stop and

then turn off the mechanical pump

Our completely assembled system is shown in figure 2-27 below

Fig 2-27 Complete System

41

Chapter 3 TENSILE TESTING IN DEPTH

31 Experimentrsquos Purpose and Principles

By means of Universal testing machine and Strain gauges we were able to observe discuss and

analyze the phenomena created when a specimen of certain material is manipulated under an external load

and determine the stress strain and deformation values later we can use the graphing methods of

stress-strain diagram to describe it

The main point of this experiment is that after the tensile specimen is tested use computer analysis

and the actual strain data and after statistical adjustment make the final results report (Tensile testing

experiment is in accordance with ASTM E8)

32 Experimentrsquos Equipment

321 Universal Testing Machine

For the materials testing experiment part of this research we use a Universal Testing Machine as

shown in figure 31 The maximum load it can apply is 100 Ton After the test specimen is secured on the

device with the use of instrumentation the load exerted and the effects of this become apparent on the

specimen and even the smallest of changes can be recorded For our research we used the Chun Yen

Testing Machines Co Ltd 100 Ton Micro Computer Universal Tensile Tester

Fig 31 Universal Testing Machine

42

Table 31 shows the specifications for this machine

Max Capacity 100 Ton

Accuracy plusmn1

Tension (mm) Max Space 1150mm

Grip for Rod 20-70mm

Ram Stroke 250mm

Effective Column Interval 940mm

Crosshead Speed 300mmmin

Testing Speed 0-50mmmin

Volume of Machine 1700times1000times3350mm(LtimesWtimesH)

Volume of Control Panel 1000times800times1500mm(LtimesWtimesH)

Weight 8000kg

Power 3∮220V 20A

Computer AMD K6-2-350

OS Windows XP

Screen 15rdquo CRT

Table 3-1 Chun Yen Testing Machine Specs Table

The connections diagram is shown in figure 3-2

Fig 3-2 Diagram for System Connections

43

When the test specimen is placed when the external force is applied the Load Cell can measure the

size of the applied force and the Encoder measures the expansion rate of change The Local Controller

receives all the information from the 2 units after arranging the results they are displayed in the

computer and they can be afterwards submitted for more complex analysis such as Finite Element

Analysis and we can get the Stress-Strain Diagram

322 Strain Measurement Equipment

The equipment used in our research provides a four-channel measurement that means we can use up

to 4 strain gauges at a time to do our measurements and provides 3 different bridge arrangements as

shown in figure 3-3

(a) (b) (c)

Fig 3-3 Input Connections for Strain Indicator

Figure 3-3 (a) is the Quarter Bridge (b) is the Half Bridge and (c) is the Full Bridge and Transducers

For our study we used the Quarter Bridge and use the Strain Gauge values to decide the position of the

connecting wires The Strain indicator is shown in figure 3-4

Fig 3-4 Vishay Micro-Measurements Model P3 Strain Indicator and Recorder

44

Input Connections Tool Free eccentric lever release

4-channel input

Wire diameter16-28AWG

Bridge Configurations Quarter- Half- and Full Bridge

Bridge Impedance 60-2000Ω

Display 128 64 pixel FSTN positive gray LCD

Data Conversion AD Converter filter

Measurement Range Resolution Strain Range plusmn155mVV

Resolution plusmn00005mVV

Measurement Accuracy plusmn01 of reading plusmn3 counts

Gage Factor Control 0500-9900

Balance Control Software either manual or automatic

Bridge Excitation 15VDC nominal

Communication Interface USB Cable Included

Data Storage Removable Media Card

Shunt Calibration Across bridge completion resistors controlled

by software When Gage Factor=200

120Ω350Ω1000Ω

Analog Output Value 0 to 25V max

Ranges plusmn320 microε plusmn3200 microε plusmn32000 microε

Error 05 output voltage +5mV

Max Error 14 output voltage + 20mV

Update rate 480 samplessec

Output Load 2000Ω

Power Battery Two Alkaline D cells

Battery life 400 hours typ

USB 5V 100mA

Operational Environment Temperature 0-50

Humidity Up to 90 Non-condensing

Case Aluminum Alloy

Size and Weight 228times152times152(mm) 20(kg)

Table 3-2 Vishay Micro-Measurements Model P3 Strain Indicator and Recorder Specs

45

323 Strain Gauge

The strain gaugersquos main basic principle is to use a resistancersquos characteristics to measure the strain

The inside connections of the strain indicator are shown in figure 3-5

Fig 3-5 Inner Connections

As shown above this is a quarter-bridge connection We connect equal-length 3 wires to the 2

connections allowed by the strain gauge wire 1 and 3 can be used to cancel out the effects of temperature

to the resistance and because of the addition of wires 1 and 3 wire 2 can directly measure the experiment

results from the strain gauge and therefore the strain developed with no influence of temperature

If there were no two measuring leads then the relations will be

R 4 =R g +2R L

Where Rg is the Strain Gauge Value and RL is the wire resistance then

4

4

R

R=

Lg

g

RR

R

2

=

gL

gg

RR

RR

21

amp

4

4

R

R=

g

g

R

R(1- L)

Where L is the Signal Loss Factor and so

L =gL

gL

RR

RR

21

2

g

L

R

2R if

g

L

R

2Rltlt1

46

(Actual Value R g =120R L =08g

L

R

2Ris always much smaller than 1)

R 4 =R g +2R LR 2 =R 3 =rR gR 1 =R g 32 RR =0

V 0 =V 2)1( r

r

(

4

4

R

R-

1

1

R

R)

The first term describes loss attenuation effects second term describes loss of balancing capabilities

effects

V 0 =V 2)1( r

r

[

)2

(Lg

g

RR

R

+

T

Lg

g

RR

R

)

2( + T

Lg

L

RR

R

)

2

2( -(

g

g

R

R) T ]

The first term describes loss attenuation effects and loss of balancing capabilities effects the second

third and fourth terms describe the temperature effects on the wire

For the three-wire method we have

L =gL

gL

RR

RR

1

g

L

R

R if

g

L

R

Rltlt1

V 0 =V 2)1( r

r

[

)(Lg

g

RR

R

+

T

Lg

g

RR

R

)( + T

Lg

L

RR

R

)

2( -

T

Lg

g

RR

R

)( - T

Lg

L

RR

R

)

2( ]

V 0 = V2)1( r

r

)(

Lg

g

RR

R

In the last four terms inside parenthesis we can see the effects of temperature being cancelled out and the

effect on first term is not great so this is the reason why in our research we use three wires

47

324 Specimen Measurements

The tensile specimens used in this research are compliant of ASTM E8 Tensile parameters as shown

in figure 3-6

Fig 3-6 Tensile Specimen

Diameter

D(mm)

Gauge

Length

G(mm)

Smallest

Arc

Radius

R(mm)

Shortest

Area

A(mm)

Total

Length

L(mm)

Clamping

Area

Length

B(mm)

Clamping

Area

Diameter

C(mm)

Bar 125 02 625 01 gt10 gt75 ~ 145 ~ 35 20

Table 3-3 Specifications for Round Bar

33 Experiment Procedure

1 Attaching the Strain Gauge to the Tensile Specimen

(1) Prepare 1 ASTM E8 compliant tensile specimen round bar as shown in figure 3-7

(2) Prepare Strain Gauge as those described in table 3-4

(3) Prepare other consumables and adhesive agent such as epoxy adhesive or

cyanoacrylate adhesive as shown in figure 3-8

48

Fig 3-7 Actual Tensile Specimen

Fig 3-8 Other Materials Used (Such as Alcohol gauze transparent tape adhesive)

Gage Type

EA-06-120LZ-120E

Resistance in ohms at 24∘C

1200plusmn03

Gage Factor at 24∘C

2075plusmn05

Transverse Sensitivity at 24∘C

(+07plusmn02)

Table 3-4 Specifications for Strain Gauge

2 Attaching Strain Gauge

As shown in following figures we shall explain the attachment of the strain gauge

(1) Use sand paper and a rasp to clean thoroughly the surface where the strain gauge will be

attached to

49

(a)

(2) Use alcohol to wash the surface where the strain gauge will be attached and use gauze to rub

it off

(b)

(3) Find a clean surface and clean it with alcohol and gauze

(c)

(4) Place the strain gauge in the clean surface Use a piece of transparent tape on top of the strain

gauge after securely placed rip it off the surface carefully

50

(d)

(5) Use a piece of white paper to mark the place where the strain gauge will be attached and in

this way we can make sure that the strain gauge will be placed as horizontally and vertically

correct as possible

(e)

(6) In the place where we had our mark place the strain gauge

(f)

(7) Carefully lift one side of the tape and apply some of the adhesive agent to both the strain

gauge and specimenrsquos surface

(g)

51

(8) We need to make sure that the gauge and the specimen will be firmly attached so we gently

apply pressure with our thumb

(h)

(9) After the adhesive is fully dry we can carefully rip off the tape

(i)

(10) We need to do the whole process twice one for the horizontally placed strain gauge and one

for the vertically placed strain gauge

52

(j)

(11) We now proceed to solder the wires to the strain gauge

(k)

(12) After soldering we use a Volt Multimeter to measure that there is no contact between wires

If there is none then the specimen is ready for testing

(l)

(13) We now need to measure a 5cm distance and mark it to check and compare the elongation

before and after the tensile testing

(m)

53

Fig 3-9 Specimen-Strain Gauge Process

3 Tensile Test

(1) Enter the computer application that controls the tensile testing machine

(2) Turn on the tensile testing machine main switch

(3) Adjust the hydraulic pump to go back to its original position

(4) Bring the lowering motor down to a distance enough so as to attach the tensile specimen to the

system open the clamps and secure the specimen

(a)

(5) Connect all the necessary wires to the strain indicator equipment

54

(b)

(6) Start the ascending motor and wait for the expansion

(c)

Fig 3-10 Specimen-Tensile Testing Process

4 Start the Test

(1) Enter the software application and enter some variables needed for the experiment in the

specific screen

(2) Go back to the main screen and press the [測試] (measure) button to start the test and auto

recording in the software

(3) After the specimen breaks the mechanical device will automatically stop and ask the user to

enter the total displacement We take out the specimen from the testing machine and adjust the

machinersquos position back to its original position

(4) Save the results information

(5) Record the results from the strain indicator

34 Results

From this experiment we can get the Poissonrsquos Ratio Youngrsquos Modulus and Yield Strength etc and

because of the slippage phenomenon in the clamp at the moment of the test then the Elastic Limit will

display some yield phenomena So omit any undesirable results we just take the Yield portion of the

results as reference

In the process of the experiment the most important part to attend to is the attaching of the strain

gauge because the gaugersquos purpose is to measure the strain developed during the test and this strain

might be very small If the gaugersquos angle change during the test ie is not well attached this will affect

the accuracy of the measurements of Poissonrsquos ratio and Youngrsquos modulus

55

The materials provided by the manufacturer are SUM 23 and SUM 43 steel round bars and these two

types of materials have been through different heat treatment processes so they can be sub-divided

further into untreated material heat-treated material and black surface heat treated material for the two

materials with heat treatment the treatment process and finished are different In the end we only have

the mechanical properties that were calculated after our research of these materials

All of the specifications are identical to those shown in figure 3-6

341 SUM 23

Fig 3-11 SUM 23 Untreated Material

Number 7 10

Hardness(HRB) 74 75

Yield Stress (MPa) 448 440

Tensile Strength (MPa) 544 560

Poissonrsquos Ratio 029 027

Youngrsquos Modulus (GPa) 203 210

Cut-off Area Shrinking () 42 41

Elongation () 1125 1011

Table 3-5 Mechanical Properties of SUM 23 Untreated

56

Stress-Strain Diagram

(a)

(b)

57

Fig 3-12 Stress-Strain Diagrams for (a) 7 Round Bar and (b) 10 Round Bar

Cut-Off Area

(a)

(b)

Fig 3-13 Cut-Off Area of (a) 7 Round Bar and (b) 10 Round Bar

58

SUM 23 Nickel Round Bar

Fig 3-14 SUM 23 Nickel Material

Number 1 2 3 4

Hardness(HRB) 48 50 49 48

Yield Stress (MPa) 370 370 380 400

Tensile Strength (MPa) 455 451 450 450

Poissonrsquos Ratio 028 046 029 026

Youngrsquos Modulus (GPa) 243 303 246 206

Cut-off Area Shrinking () 803 803 726 601

Elongation () 566 65 602 647

Table 3-6 Mechanical Properties of SUM 23 Nickel

59

Stress-Strain Diagram

(a)

60

(b)

(c)

(d)

61

Fig 3-15 Stress-Strain Diagrams for (a) 1 Round Bar (b) 2 Round Bar (c) 3 Round Bar and (d)

4 Round Bar

Cut-Off Area

(a)

(b)

62

(c)

(d)

Fig 3-16 Cut-Off Area of (a) 1 Round Bar (b) 2 Round Bar (c) 3 Round Bar and (d) 4 Round

Bar

63

SUM 23 Black Surface Round Bar

Fig 3-17 SUM 23 Black Surface Material

Number 1 2 3

Hardness(HRB) 51 50 51

Yield Stress (MPa) 378 371 369

Tensile Strength (MPa) 467 465 464

Poissonrsquos Ratio 03 016 04

Youngrsquos Modulus (GPa) 215 266 266

Cut-off Area Shrinking () 986 94 848

Elongation () 748 805 761

Table 3-7 Mechanical Properties of SUM 23 Black Surface Material

64

Stress-Strain Diagram

(a)

(b)

65

(c)

Fig 3-18 Stress-Strain Diagrams for (a) 1 Round Bar 2 Round Bar and (c) 3 Round Bar

Cut-Off Surface

(a)

66

(b)

(c)

Fig 3-19 Cut-Off Surface of (a) 1 Round Bar 2 Round Bar and (c) 3 Round Bar

67

342 SUM 43

Fig 3-20 Untreated SUM 43 Untreated Material

Number 1 5

Hardness(HRB) 76 75

Yield Stress (MPa) 572 594

Tensile Strength (MPa) 743 785

Poissonrsquos Ratio 027 029

Youngrsquos Modulus (GPa) 200 202

Cut-off Area Shrinking () 338 2944

Elongation () 857 894

Table 3-8 Mechanical Properties of SUM 43 Untreated

68

Stress-Strain Diagrams

(a)

(b)

Fig 3-21 Stress-Strain Diagrams for SUM 43 (a) 1 Round Bar and (b) 5 Round Bar

69

Cut-Off Area

(a)

(b)

Fig 3-22 Cut-Off Area of SUM 43 (a) 1 Round Bar and (b) 5 Round Bar

70

SUM 43 Nickel Round Bar

Fig 3-23 SUM 43 Nickel Material

Number 4 5

Hardness(HRB) 51 50

Yield Stress (MPa) 1580 1544

Tensile Strength (MPa) 1639 1625

Poissonrsquos Ratio 03 028

Youngrsquos Modulus (GPa) 194 201

Cut-off Area Shrinking () 1697 137

Elongation () 376 265

Table 3-9 Mechanical Properties of SUM 43 Nickel

71

Stress-Strain Diagrams

(a)

(b)

Fig 3-24 Stress-Strain Diagrams for (a) 4 Round Bar and (b) 5 Round Bar

72

Cut-Off Area

(a)

(b)

Fig 3-25 Cut-Off Area of (a) 4 Round Bar and (b) 5 Round Bar

73

SUM 43 Black Surface Material

Fig 3-26 SUM 43 Black Surface Material

Number 3 5

Hardness(HRB) 56 56

Yield Stress (MPa) 1416 1361

Tensile Strength (MPa) 1591 1402

Poissonrsquos Ratio 029 031

Youngrsquos Modulus (GPa) 200 202

Cut-off Area Shrinking () 139 124

Elongation () 24 24

Table 3-10 Mechanical Properties of SUM 43 Black Surface Material

74

Stress-Strain Diagrams

0 2 4 6 8 10 12 14

-200

0

200

400

600

800

1000

1200

1400

1600

1800

應力 (MPa)

應變()

(a)

0 2 4 6 8 10

-200

0

200

400

600

800

1000

1200

1400

1600

應力

(MPa)

位移 ()

(b)

Fig 3-27 Stress-Strain Diagrams for (a) 3 Round Bar and (b) 5 Round Bar

(Note These curves were formulated using Visual Solutions Inc VisSim Software)

75

Cut-Off Area

(a)

(b)

Fig 3-28 Cut-Off Area of (a) 3 Round Bar and (b) 5 Round Bar

76

The force value (N) was retrieved from the Universal Testing Machine

The Poissonrsquos Ratio (ε) is calculated as

ε =

the values for the Poissonrsquos Ratio are in average around 0297

The Youngrsquos Modulus (E) is calculated as

E =

Where

Stress =

Cross-sectional Area =

where D is the Diameter

The value for D was in average around 1258 mm

The values shown by the computer because there is Slippage phenomena between the Clamp and the

specimen will not be taken into consideration for the elongation strain and Youngrsquos modulus and we will

refer to the values that we have meticulously calculated

77

Chapter 4 AR COATING IN DEPTH

41 Experimentrsquos Purpose and Principles

By means of a vacuum chamber and several other instruments we intend to apply Anti-Reflective

Coating using deposition process to a laser diode and in this way reduce its refraction so as to make it

lose less light in the process of amplification and we can control certain wavelengths we want produced

for certain desired applications in our case we are attempting to re-create a Bose-Einstein Condensate

An optimal BEC apparatus is shown in figure 4-1

Fig 4-1 BEC Apparatus

The main point of this experiment is to build a vacuum chamber system attach all the instrumentation

needed (Vacuum pump deposition meter and voltmeter) and use it to apply AR coating to a laser diode

After we have accomplished the AR coating other team will be in charge of designing the BEC apparatus

and use the results of our research

78

42 Experimentrsquos Equipment

421 Vacuum Chamber

For this research we designed a vacuum chamber whose main body is shown in figure 4-2 Its

dimensions are

Width 240 mm

Length 240 mm

Height 200 mm

Outer Diameter 4 in

Inner Diameter 15 in

Fig 4-2 Vacuum Chamber Main Body

The chamber is made up of 6 pass ways pass way A is the connection with the Laser Deposition

Equipment pass way B is the connection with the Turbo Pump and pass way C is for the connection with

the Deposition Source

A

C

B

79

Pass way C is for the deposition source as mentioned above This is a system where a thermal

resistance is heated by passing a high current through it which heats up a filament boat (made of tungsten)

where the material to be evaporated is place We control the temperature as such that the material will

evaporate and the heat will not cause the filament boat to crack

Because P = Isup2 R (where P is power I is current and R is resistance) to avoid the current to flow

where it is not desired we decided that the material for the Thermocouple shown in figure 4-3 should be

Copper ᴓ 63 mm We choose it that way because Copper has very good heat dissipation characteristics

and the resistance value is low It can reduce the value of the current enough to make the thermocouple to

create heat

Fig 4-3 Thermocouple

To the thermocouple we attach the tungsten filament boat We need to take notice of materials to be

used in this design because when using high current the tungsten filament boar will heat up and so the

material must be able to keep up with the heating potential of tungsten and has a low coefficient of heat

dissipation to avoid the tungsten to fail when heating up and therefore not evaporating Considering all

this we decide to use Stainless Steel

Because this clamp will be assembled inside the chamber after many revisions it was determined it

will have the shape shown in figure 4-4

Fig 4-4 Filament Boat Clamp Design

80

For the tungsten filament boat we bought the product from a distributor The dimensions are

Length 100 mm

Width 10 mm

Height 1 mm

Our thermocouple is 15 in but the pass way C is 4 in so we need to attach a Flange that connects

15in to 4in Because these specifications are quite difficult to achieve by Milling we had to use

electrical wire cutting

For the laser clamping system where the laser that is going to be AR coated will be placed will be

connected to pass way A the assembly is shown in figure 4-5 below

Fig 4-5 Cover Assembly

For this design we used an O-ring instead of a gasket so as to save time The design of the assembly

where the laser will be placed is shown in figure 4-6

Fig 4-6 Upper Cover Inner Assembly

D

E

F

81

Point D is the plate in the assembly where the laser diode will be fixed Because of the easy

processing we decide to use Aluminum and it is screwed to the top cover Point E is the connection for

the Quartz crystal resonator and it is designed in the same as point F in this way the results of the quartz

microbalance system will be more accurate in real time Point F is the final resting place for the laser

diode We use a Thor Labs Base with dimensions of ᴓ 9mm and ᴓ 56mm for two different size laser

diodes It just needs to be plugged in for easy installation

From figure 4-6 we know that the system needs signal system connections and because of the

change in temperature inside the chamber this could affect the functioning of the quartz microbalance so

we also need to install water tubes for cooling This is shown in figure 4-7 below

Fig 4-7 Diagram of Upper Cover Connections

In figure 4-8 we show the Feed through connections and their functions

Fig 4-8 Feed through Diagram

82

1 SQM-160 wire 5 Laser Connection 1 (Vin)

2 SQM-160 (G) 6 Laser Connection 2 (G)

3 K-Type-1 7 Laser Connection 3 (PD)

4 K-Type-2 8 Not In Use

The fully assembled chamber is shown in figure 4-9

Fig 4-9 Fully Assembled Chamber

422 Quartz Crystal Microbalance

For measuring the deposition on our target for coating we used the Inficon SQM-160 RateThickness

Monitor It is an easy to use instrument for measuring many types of thin-film coatings as shown in

figure 4-10

(a) Front Panel (b) Back Panel

Fig 4-10 Inficon SQM-160

83

Table 4-1 shows the technical specifications for this equipment

Number of sensors 2 Standard 4 additional optional

Sensor Frequency Range 40 MHz ~ 60 MHz

Reference Frequency Accuracy 002

Thickness Display Resolution 1 Aring

Thickness Resolution 015 Aring (Std) 0037 Aring (Hi Res)

Density of Stored Films 05-9999 gmcc

Tooling 10-399

Z-Factor 010-1000

Final Thickness 0000-9999k Aring

Measurement Period 15 to 2 sec

Simulation Mode Yes

Frequency Mode Yes

Rate Resolution 011 Arings

Dual Crystal Yes

Etch Mode Yes

Crystal Tooling 10-399

Crystal Fail Min Max 40 to 60 MHz 41 to 61 MHz

Power 100-120 200-240~plusmn10 nominal 20W

Operation Environment 0degC ~ 50degC

0 ~ 80 RH non-condensing

0 ~ 2000 meters

Class 1 Equipment

Pollution Degree 2

Rack Dimensions 885mm x 2127mm x 1969mm

Weight 27 kg

Table 4-1 Inficon SQM-160 RateThickness Monitor Specs

84

To the SQM-160 we need to connect an Oscillator We use the Sigma Instruments Remote Oscillator

Ser No 2 268 as shown in figure 4-11

Fig 4-11 Sigma Instruments Remote Oscillator

The connections diagram is shown in figure 4-12

Fig 4-12 SQM-160 Connections Diagram

85

423 Turbo Pump

For our experiments we used the Pfeiffer TCP 015 Electronic Drive Unit shown below in figure 4-13

Table 4-2 shows the technical specifications for this equipment

(a) Front Panel (b) Back Panel

Fig 4-13 Pfeiffer TCP 015 Electronic Drive

Connection Voltage (100V) 90-112

Mains Frequency 5060 Hz

Start-up Current 22 A

Nominal Frequency 1500 Hz

Rotation Speed 10V = 1500Hz plusmn2

Analog Output Current 10 V = 25 A plusmn 5

Rotation Speed Switchpoint 750 Hz

Works Setting 8 min

Permissible Ambient Temperature 0degC ~ 40degC

Dimensions Front Panel 1285mm x 1063mm

Insertion Length 227mm

Weight 27 Kg

Table 4-2 Pfeiffer TCP 015 Electronic Drive Specs

86

The connections diagram is shown in figure 4-14

Fig 4-14Connections Diagram for Pfeiffer TCP 015

To measure the pressure inside the chamber we use the Granville Phillips 375 Convectron Vacuum

Pressure Controller shown in figure 4-15

(a) Front Panel (b) Back Panel

Fig 4-15 Granville Phillips 375 Convectron

87

Its dimensions are shown in figure 4-16

Fig 4-16 Dimensions of Convectron

Table 4-3 shows the technical specifications for this equipment

Table 4-3 Granville Phillips 375 Convectron Vacuum Pressure Controller Specs

88

424 Multimeter

For our experiment we used the Keithley 2000 Digital Multimeter as shown in figure 4-17

(a) Front Panel (b) Back Panel

Fig 4-17 Keithley Model 2000 6-12-Digit Digital Multimeter

Its technical specifications are shown in table 4-4

Table 4-4 Keithley Model 2000 6-12-Digit Digital Multimeter Specs

89

43 Experiment Procedure

1 Connecting together the equipment and the chamber

(1) We first connect the resonator to the thickness monitor and connect the other side to the

chamber

(2) We now connect the flexible tubes to the turbo pump on one side and to the chamber on the

other

(3) We need to check that tubes are tightly connected to avoid any leaks in the vacuum pumping

process which will not allow us to get to our goal of Torr As shown in figure 4-18

(4) Connect the convectron to the system as shown in figure 4-19

Fig 4-18 checking for leaks using alcohol

Fig 4-19 Convectron attached to System

90

(5) Attach the clamps of the Multimeter to the bottom of the chamber as shown in figure 4-20

(6) Place the Quartz crystal in place

(7) Close tight vacuum chamber

(8) Connect all electrical appliances to power source

Fig 4-20 Multimeter Connections

2 Starting up the System

(1) We turn on all the devices as such Check all systems are ready to function Reset all values

that might be left over from previous tests

(2) Start the thickness monitor and set all values for this experiment In our case we got to testing

the system but not actual coating So we used the simulation mode of the thickness monitor as

shown in figure 4-21

Fig 4-21 Simulation Mode

91

(3) Start the turbo pump Make sure the lid on the vacuum chamber is tightly closed

(4) Start convectron and record initial pressure

(5) Start Multimeter and record initial current

3 Coating Process

(1) If we have the deposition material inside the filament boat the power source for the high

current must be started as well

(2) Record all initial values for thickness current pressure

(3) For an ideal experiment we need a thickness of around 101 nm a pressure of Torr and

a current of 300 A

44 Results

From previous experiments we have shown that we can turn a LED into a laser by means of AR

Coating In figure 4-22 shown below we can compare the actual results of a Diode before and after AR

coating From the blue line we can see that when the diode is at a current of 15mA its light will change

from LED to laser and if we look at the red line its critical current is around 30 to 35 mA

Fig 4-22 AR Coating Comparison for Laser Diodes

This means that the light emitted is not as strong as if the diode had been coated because inside the

chamber there must be some excitation first so the reflectivity of both sides inside the diode must be high

So because of the coating in one of the sides we have opened a door and let the light come out so the

critical current is risen as such and will be higher value than that of before the coating

92

In the following figures we can see the difference between before and after coating in a material The

thickness is around 1016 nm for this material

Fig 4-23 Before Coating

Fig 4-24 After Coating

93

Chapter 5 CONCLUSIONS AND RECOMMENDATIONS

51 Conclusions

For the first part of this independent study taking into consideration the data that came out of our

research and that sent by the provider we can say

1 SUM 23 after heat treatment will unexpectedly develop cracking in the middle of the tensile

testing process and suddenly break

2 Itrsquos possible that in the process of heat treatment to the SUM 23 material the treatment was not

uniform and this will create a pre-loaded moment force on one side that pushes on the other side

of the specimen resulting in material deformation

3 In the process of attaching the strain gauges to the materials it is very easy to make errors due to

poor adhesion or sudden removal in the tensile testing process

For our second part of the independent study the following can be made

1 At the beginning of this independent study we had no idea what Bose-Einstein Condensate was

or what was its purpose After much literature we finally comprehended the basic principles to

put into practice for our research

2 Our systemrsquos basic working principles and equipmentrsquos complexity are a little difficult to grasp

but hopefully we were able to understand enough of it

3 Theoretically from relation between the power and current we can know the advantages and

disadvantages of AR Coating

4 We were able to assemble the system and run test on its functions Even though we were able to

do this there is still much more work left to do with this system

52 Recommendations

For the Tensile Testing the following can be said

1 Ask the provider to check on the process of heat treatment on the SUM 23 material and give

them the information we have gathered through our test so they can correct for the mechanical

properties found if any change is needed

2 To avoid the problem of the inaccuracy of the poor adhesion of strain gauges we can attach

multiple strain gauges to the same one specimen so as to correlate data and improve our results

For the AR Coating the following can be said

1 We need to make sure that there are no physical defects on the main body of the chamber so as to

achieve maximum efficiency in the vacuum process If there was then the vacuum will arrive to

certain point and then start to decrease

2 It would be preferable to add some sort of visual aid that will allow the user to check the inside of

the chamber without actually opening it This will help us determine at what times we should

manipulate the current to better evaporate the substrate

94

REFERENCES

[1] A L Window Strain Gauge Technology Elsevier Applied Science London and New York 2nd

Edition 1992

[2] CC Perry and HR Lissner Strain Gauge Primer McGraw-Hill Book Co Inc New York 1955

[3] James W Dally William F Riley McGraw-Hill 1978

[4] University of Colorado Boulder BEC - What is it and where did the idea come from

httpwwwcoloradoeduphysics2000becwhat_is_ithtml

[5] Ultraslow Light amp Bose-Einstein Condensates Two-way Control with Coherent Light amp Atom

Fields Harvard Hau Lab Dr Lene Vestergaard Hau Optics amp Photonics News 16 1995

[6] The Art of Taming Light Ultra-slow and Stopped Light Harvard Hau Lab Dr Lene

Vestergaard Hau Europhysics News 2004

[7] Nonlinear Optics Shocking Superfluids Harvard Hau Lab Dr Lene Vestergaard Hau Nature

Physics 2007

[8] Model P3 Strain Indicator and Recorder Instruction Manual Vishay Micro-Measurements 2005

[9] Granville-Phillips Series 375 Convectron Vacuum Gauge Controller Instruction Manual Brooks

Automation 2008

[10] Effect of Film Thickness on the Validity of the Sauerbrey Equation for Hydrated Polyelectrolyte

Films Vogt Lin Wu White 2004

[11] Quartz Crystal Microbalance Study of DNA Immobilization and Hybridization for DNA Sensor

Development Chang Zhao 2008

[12] Installation of Strain Gages with SR-4 PrecoatAdhesive Vishay Micro-Measurements 2005

[13] Strain Gauge Measurement ndash A Tutorial National Instruments 1998

[14] Correlation between Vickers Hardness Number and Yield Stress of Cold-Formed Products

Yavuz Tekkaya

[15] httpsenwikipediaorg

Page 35: PC Hinge Materials Testing and AR Laser Diode Coating

35

Table 2-2 Continued

36

Table 2-2 Continued

37

Table 2-2 Continued

38

Table 2-2 Continued

235 Vacuum Chamber System

Vacuum Evaporation is the process of depositing thin films of materials onto surfaces The technique

consists of pumping a vacuum chamber to pressures of less than torr and heating a material to

produce a flux of vapor in order to deposit the material onto a surface The material to be vaporized is

typically heated until its vapor pressure is high enough to produce a flux several Angstrom per second by

using an electrically resistive heater or bombardment by a high voltage beam The process was invented

by Henri Nestle in 1886 for food industry

In here the system has been pumped to a vacuum of Torr When a high current is passed

through the filament boat the filament boat is heated over the desired metal evaporation temperature and

so evaporation starts When the evaporation process is finished and the metal cools down crystals

condensate in the surface of the wafer From the weight of the evaporated material the distance between

the filament boat and the wafer we are able to calculate the deposition thickness and we can also use the

mass detector follower like the Quartz crystal resonator microbalance system In the process of

evaporation we usually use a board in between the filament boat and the wafer This is because before we

arrive to the desired evaporation temperature there will be some impurities that will be vaporized in the

controlled environment so we first use a small current and the board in between to get rid of those

impurities and this raises the purity of the deposition material

39

A vacuum evaporation system is shown in figure 2-24

Fig 2-24 Vacuum Evaporation System

Rough Vacuum 760 ~ 1 torr

Medium Vacuum 1 ~ torr

High Vacuum ~ torr

Ultra-High Vacuum Lower than torr

Table 2-3 Classification of Vacuum

For our study we need to use a Turbo Pump A regular turbo pump is shown in figure 2-25

Fig 2-25 Turbo Pump

For our research we used the Pfeiffer TCP 015 Electronic Drive Unit and Granville Phillips 375

Convectron shown below in figure 2-26

40

Fig 2-26 Control and Measurement Equipment

The electronic drive controls the turbo pump and the Convectron measures the pressure inside our

chamber The turbo pump is a type of vacuum pump used to maintain high vacuum Most turbo pumps

are centrifugal When we start the pumping we need to use a mechanical pump so as to decrease the

pressure inside the system from constant atmospheric pressure to torr and then the use dispersion

pump to continue the vacuum until we get to the desired pressure We need to notice though when we

start the dispersion pump we canrsquot turn off the mechanical pump and they both need to run together If

we need to turn off the pumping we first turn off the dispersion pump wait for it to completely stop and

then turn off the mechanical pump

Our completely assembled system is shown in figure 2-27 below

Fig 2-27 Complete System

41

Chapter 3 TENSILE TESTING IN DEPTH

31 Experimentrsquos Purpose and Principles

By means of Universal testing machine and Strain gauges we were able to observe discuss and

analyze the phenomena created when a specimen of certain material is manipulated under an external load

and determine the stress strain and deformation values later we can use the graphing methods of

stress-strain diagram to describe it

The main point of this experiment is that after the tensile specimen is tested use computer analysis

and the actual strain data and after statistical adjustment make the final results report (Tensile testing

experiment is in accordance with ASTM E8)

32 Experimentrsquos Equipment

321 Universal Testing Machine

For the materials testing experiment part of this research we use a Universal Testing Machine as

shown in figure 31 The maximum load it can apply is 100 Ton After the test specimen is secured on the

device with the use of instrumentation the load exerted and the effects of this become apparent on the

specimen and even the smallest of changes can be recorded For our research we used the Chun Yen

Testing Machines Co Ltd 100 Ton Micro Computer Universal Tensile Tester

Fig 31 Universal Testing Machine

42

Table 31 shows the specifications for this machine

Max Capacity 100 Ton

Accuracy plusmn1

Tension (mm) Max Space 1150mm

Grip for Rod 20-70mm

Ram Stroke 250mm

Effective Column Interval 940mm

Crosshead Speed 300mmmin

Testing Speed 0-50mmmin

Volume of Machine 1700times1000times3350mm(LtimesWtimesH)

Volume of Control Panel 1000times800times1500mm(LtimesWtimesH)

Weight 8000kg

Power 3∮220V 20A

Computer AMD K6-2-350

OS Windows XP

Screen 15rdquo CRT

Table 3-1 Chun Yen Testing Machine Specs Table

The connections diagram is shown in figure 3-2

Fig 3-2 Diagram for System Connections

43

When the test specimen is placed when the external force is applied the Load Cell can measure the

size of the applied force and the Encoder measures the expansion rate of change The Local Controller

receives all the information from the 2 units after arranging the results they are displayed in the

computer and they can be afterwards submitted for more complex analysis such as Finite Element

Analysis and we can get the Stress-Strain Diagram

322 Strain Measurement Equipment

The equipment used in our research provides a four-channel measurement that means we can use up

to 4 strain gauges at a time to do our measurements and provides 3 different bridge arrangements as

shown in figure 3-3

(a) (b) (c)

Fig 3-3 Input Connections for Strain Indicator

Figure 3-3 (a) is the Quarter Bridge (b) is the Half Bridge and (c) is the Full Bridge and Transducers

For our study we used the Quarter Bridge and use the Strain Gauge values to decide the position of the

connecting wires The Strain indicator is shown in figure 3-4

Fig 3-4 Vishay Micro-Measurements Model P3 Strain Indicator and Recorder

44

Input Connections Tool Free eccentric lever release

4-channel input

Wire diameter16-28AWG

Bridge Configurations Quarter- Half- and Full Bridge

Bridge Impedance 60-2000Ω

Display 128 64 pixel FSTN positive gray LCD

Data Conversion AD Converter filter

Measurement Range Resolution Strain Range plusmn155mVV

Resolution plusmn00005mVV

Measurement Accuracy plusmn01 of reading plusmn3 counts

Gage Factor Control 0500-9900

Balance Control Software either manual or automatic

Bridge Excitation 15VDC nominal

Communication Interface USB Cable Included

Data Storage Removable Media Card

Shunt Calibration Across bridge completion resistors controlled

by software When Gage Factor=200

120Ω350Ω1000Ω

Analog Output Value 0 to 25V max

Ranges plusmn320 microε plusmn3200 microε plusmn32000 microε

Error 05 output voltage +5mV

Max Error 14 output voltage + 20mV

Update rate 480 samplessec

Output Load 2000Ω

Power Battery Two Alkaline D cells

Battery life 400 hours typ

USB 5V 100mA

Operational Environment Temperature 0-50

Humidity Up to 90 Non-condensing

Case Aluminum Alloy

Size and Weight 228times152times152(mm) 20(kg)

Table 3-2 Vishay Micro-Measurements Model P3 Strain Indicator and Recorder Specs

45

323 Strain Gauge

The strain gaugersquos main basic principle is to use a resistancersquos characteristics to measure the strain

The inside connections of the strain indicator are shown in figure 3-5

Fig 3-5 Inner Connections

As shown above this is a quarter-bridge connection We connect equal-length 3 wires to the 2

connections allowed by the strain gauge wire 1 and 3 can be used to cancel out the effects of temperature

to the resistance and because of the addition of wires 1 and 3 wire 2 can directly measure the experiment

results from the strain gauge and therefore the strain developed with no influence of temperature

If there were no two measuring leads then the relations will be

R 4 =R g +2R L

Where Rg is the Strain Gauge Value and RL is the wire resistance then

4

4

R

R=

Lg

g

RR

R

2

=

gL

gg

RR

RR

21

amp

4

4

R

R=

g

g

R

R(1- L)

Where L is the Signal Loss Factor and so

L =gL

gL

RR

RR

21

2

g

L

R

2R if

g

L

R

2Rltlt1

46

(Actual Value R g =120R L =08g

L

R

2Ris always much smaller than 1)

R 4 =R g +2R LR 2 =R 3 =rR gR 1 =R g 32 RR =0

V 0 =V 2)1( r

r

(

4

4

R

R-

1

1

R

R)

The first term describes loss attenuation effects second term describes loss of balancing capabilities

effects

V 0 =V 2)1( r

r

[

)2

(Lg

g

RR

R

+

T

Lg

g

RR

R

)

2( + T

Lg

L

RR

R

)

2

2( -(

g

g

R

R) T ]

The first term describes loss attenuation effects and loss of balancing capabilities effects the second

third and fourth terms describe the temperature effects on the wire

For the three-wire method we have

L =gL

gL

RR

RR

1

g

L

R

R if

g

L

R

Rltlt1

V 0 =V 2)1( r

r

[

)(Lg

g

RR

R

+

T

Lg

g

RR

R

)( + T

Lg

L

RR

R

)

2( -

T

Lg

g

RR

R

)( - T

Lg

L

RR

R

)

2( ]

V 0 = V2)1( r

r

)(

Lg

g

RR

R

In the last four terms inside parenthesis we can see the effects of temperature being cancelled out and the

effect on first term is not great so this is the reason why in our research we use three wires

47

324 Specimen Measurements

The tensile specimens used in this research are compliant of ASTM E8 Tensile parameters as shown

in figure 3-6

Fig 3-6 Tensile Specimen

Diameter

D(mm)

Gauge

Length

G(mm)

Smallest

Arc

Radius

R(mm)

Shortest

Area

A(mm)

Total

Length

L(mm)

Clamping

Area

Length

B(mm)

Clamping

Area

Diameter

C(mm)

Bar 125 02 625 01 gt10 gt75 ~ 145 ~ 35 20

Table 3-3 Specifications for Round Bar

33 Experiment Procedure

1 Attaching the Strain Gauge to the Tensile Specimen

(1) Prepare 1 ASTM E8 compliant tensile specimen round bar as shown in figure 3-7

(2) Prepare Strain Gauge as those described in table 3-4

(3) Prepare other consumables and adhesive agent such as epoxy adhesive or

cyanoacrylate adhesive as shown in figure 3-8

48

Fig 3-7 Actual Tensile Specimen

Fig 3-8 Other Materials Used (Such as Alcohol gauze transparent tape adhesive)

Gage Type

EA-06-120LZ-120E

Resistance in ohms at 24∘C

1200plusmn03

Gage Factor at 24∘C

2075plusmn05

Transverse Sensitivity at 24∘C

(+07plusmn02)

Table 3-4 Specifications for Strain Gauge

2 Attaching Strain Gauge

As shown in following figures we shall explain the attachment of the strain gauge

(1) Use sand paper and a rasp to clean thoroughly the surface where the strain gauge will be

attached to

49

(a)

(2) Use alcohol to wash the surface where the strain gauge will be attached and use gauze to rub

it off

(b)

(3) Find a clean surface and clean it with alcohol and gauze

(c)

(4) Place the strain gauge in the clean surface Use a piece of transparent tape on top of the strain

gauge after securely placed rip it off the surface carefully

50

(d)

(5) Use a piece of white paper to mark the place where the strain gauge will be attached and in

this way we can make sure that the strain gauge will be placed as horizontally and vertically

correct as possible

(e)

(6) In the place where we had our mark place the strain gauge

(f)

(7) Carefully lift one side of the tape and apply some of the adhesive agent to both the strain

gauge and specimenrsquos surface

(g)

51

(8) We need to make sure that the gauge and the specimen will be firmly attached so we gently

apply pressure with our thumb

(h)

(9) After the adhesive is fully dry we can carefully rip off the tape

(i)

(10) We need to do the whole process twice one for the horizontally placed strain gauge and one

for the vertically placed strain gauge

52

(j)

(11) We now proceed to solder the wires to the strain gauge

(k)

(12) After soldering we use a Volt Multimeter to measure that there is no contact between wires

If there is none then the specimen is ready for testing

(l)

(13) We now need to measure a 5cm distance and mark it to check and compare the elongation

before and after the tensile testing

(m)

53

Fig 3-9 Specimen-Strain Gauge Process

3 Tensile Test

(1) Enter the computer application that controls the tensile testing machine

(2) Turn on the tensile testing machine main switch

(3) Adjust the hydraulic pump to go back to its original position

(4) Bring the lowering motor down to a distance enough so as to attach the tensile specimen to the

system open the clamps and secure the specimen

(a)

(5) Connect all the necessary wires to the strain indicator equipment

54

(b)

(6) Start the ascending motor and wait for the expansion

(c)

Fig 3-10 Specimen-Tensile Testing Process

4 Start the Test

(1) Enter the software application and enter some variables needed for the experiment in the

specific screen

(2) Go back to the main screen and press the [測試] (measure) button to start the test and auto

recording in the software

(3) After the specimen breaks the mechanical device will automatically stop and ask the user to

enter the total displacement We take out the specimen from the testing machine and adjust the

machinersquos position back to its original position

(4) Save the results information

(5) Record the results from the strain indicator

34 Results

From this experiment we can get the Poissonrsquos Ratio Youngrsquos Modulus and Yield Strength etc and

because of the slippage phenomenon in the clamp at the moment of the test then the Elastic Limit will

display some yield phenomena So omit any undesirable results we just take the Yield portion of the

results as reference

In the process of the experiment the most important part to attend to is the attaching of the strain

gauge because the gaugersquos purpose is to measure the strain developed during the test and this strain

might be very small If the gaugersquos angle change during the test ie is not well attached this will affect

the accuracy of the measurements of Poissonrsquos ratio and Youngrsquos modulus

55

The materials provided by the manufacturer are SUM 23 and SUM 43 steel round bars and these two

types of materials have been through different heat treatment processes so they can be sub-divided

further into untreated material heat-treated material and black surface heat treated material for the two

materials with heat treatment the treatment process and finished are different In the end we only have

the mechanical properties that were calculated after our research of these materials

All of the specifications are identical to those shown in figure 3-6

341 SUM 23

Fig 3-11 SUM 23 Untreated Material

Number 7 10

Hardness(HRB) 74 75

Yield Stress (MPa) 448 440

Tensile Strength (MPa) 544 560

Poissonrsquos Ratio 029 027

Youngrsquos Modulus (GPa) 203 210

Cut-off Area Shrinking () 42 41

Elongation () 1125 1011

Table 3-5 Mechanical Properties of SUM 23 Untreated

56

Stress-Strain Diagram

(a)

(b)

57

Fig 3-12 Stress-Strain Diagrams for (a) 7 Round Bar and (b) 10 Round Bar

Cut-Off Area

(a)

(b)

Fig 3-13 Cut-Off Area of (a) 7 Round Bar and (b) 10 Round Bar

58

SUM 23 Nickel Round Bar

Fig 3-14 SUM 23 Nickel Material

Number 1 2 3 4

Hardness(HRB) 48 50 49 48

Yield Stress (MPa) 370 370 380 400

Tensile Strength (MPa) 455 451 450 450

Poissonrsquos Ratio 028 046 029 026

Youngrsquos Modulus (GPa) 243 303 246 206

Cut-off Area Shrinking () 803 803 726 601

Elongation () 566 65 602 647

Table 3-6 Mechanical Properties of SUM 23 Nickel

59

Stress-Strain Diagram

(a)

60

(b)

(c)

(d)

61

Fig 3-15 Stress-Strain Diagrams for (a) 1 Round Bar (b) 2 Round Bar (c) 3 Round Bar and (d)

4 Round Bar

Cut-Off Area

(a)

(b)

62

(c)

(d)

Fig 3-16 Cut-Off Area of (a) 1 Round Bar (b) 2 Round Bar (c) 3 Round Bar and (d) 4 Round

Bar

63

SUM 23 Black Surface Round Bar

Fig 3-17 SUM 23 Black Surface Material

Number 1 2 3

Hardness(HRB) 51 50 51

Yield Stress (MPa) 378 371 369

Tensile Strength (MPa) 467 465 464

Poissonrsquos Ratio 03 016 04

Youngrsquos Modulus (GPa) 215 266 266

Cut-off Area Shrinking () 986 94 848

Elongation () 748 805 761

Table 3-7 Mechanical Properties of SUM 23 Black Surface Material

64

Stress-Strain Diagram

(a)

(b)

65

(c)

Fig 3-18 Stress-Strain Diagrams for (a) 1 Round Bar 2 Round Bar and (c) 3 Round Bar

Cut-Off Surface

(a)

66

(b)

(c)

Fig 3-19 Cut-Off Surface of (a) 1 Round Bar 2 Round Bar and (c) 3 Round Bar

67

342 SUM 43

Fig 3-20 Untreated SUM 43 Untreated Material

Number 1 5

Hardness(HRB) 76 75

Yield Stress (MPa) 572 594

Tensile Strength (MPa) 743 785

Poissonrsquos Ratio 027 029

Youngrsquos Modulus (GPa) 200 202

Cut-off Area Shrinking () 338 2944

Elongation () 857 894

Table 3-8 Mechanical Properties of SUM 43 Untreated

68

Stress-Strain Diagrams

(a)

(b)

Fig 3-21 Stress-Strain Diagrams for SUM 43 (a) 1 Round Bar and (b) 5 Round Bar

69

Cut-Off Area

(a)

(b)

Fig 3-22 Cut-Off Area of SUM 43 (a) 1 Round Bar and (b) 5 Round Bar

70

SUM 43 Nickel Round Bar

Fig 3-23 SUM 43 Nickel Material

Number 4 5

Hardness(HRB) 51 50

Yield Stress (MPa) 1580 1544

Tensile Strength (MPa) 1639 1625

Poissonrsquos Ratio 03 028

Youngrsquos Modulus (GPa) 194 201

Cut-off Area Shrinking () 1697 137

Elongation () 376 265

Table 3-9 Mechanical Properties of SUM 43 Nickel

71

Stress-Strain Diagrams

(a)

(b)

Fig 3-24 Stress-Strain Diagrams for (a) 4 Round Bar and (b) 5 Round Bar

72

Cut-Off Area

(a)

(b)

Fig 3-25 Cut-Off Area of (a) 4 Round Bar and (b) 5 Round Bar

73

SUM 43 Black Surface Material

Fig 3-26 SUM 43 Black Surface Material

Number 3 5

Hardness(HRB) 56 56

Yield Stress (MPa) 1416 1361

Tensile Strength (MPa) 1591 1402

Poissonrsquos Ratio 029 031

Youngrsquos Modulus (GPa) 200 202

Cut-off Area Shrinking () 139 124

Elongation () 24 24

Table 3-10 Mechanical Properties of SUM 43 Black Surface Material

74

Stress-Strain Diagrams

0 2 4 6 8 10 12 14

-200

0

200

400

600

800

1000

1200

1400

1600

1800

應力 (MPa)

應變()

(a)

0 2 4 6 8 10

-200

0

200

400

600

800

1000

1200

1400

1600

應力

(MPa)

位移 ()

(b)

Fig 3-27 Stress-Strain Diagrams for (a) 3 Round Bar and (b) 5 Round Bar

(Note These curves were formulated using Visual Solutions Inc VisSim Software)

75

Cut-Off Area

(a)

(b)

Fig 3-28 Cut-Off Area of (a) 3 Round Bar and (b) 5 Round Bar

76

The force value (N) was retrieved from the Universal Testing Machine

The Poissonrsquos Ratio (ε) is calculated as

ε =

the values for the Poissonrsquos Ratio are in average around 0297

The Youngrsquos Modulus (E) is calculated as

E =

Where

Stress =

Cross-sectional Area =

where D is the Diameter

The value for D was in average around 1258 mm

The values shown by the computer because there is Slippage phenomena between the Clamp and the

specimen will not be taken into consideration for the elongation strain and Youngrsquos modulus and we will

refer to the values that we have meticulously calculated

77

Chapter 4 AR COATING IN DEPTH

41 Experimentrsquos Purpose and Principles

By means of a vacuum chamber and several other instruments we intend to apply Anti-Reflective

Coating using deposition process to a laser diode and in this way reduce its refraction so as to make it

lose less light in the process of amplification and we can control certain wavelengths we want produced

for certain desired applications in our case we are attempting to re-create a Bose-Einstein Condensate

An optimal BEC apparatus is shown in figure 4-1

Fig 4-1 BEC Apparatus

The main point of this experiment is to build a vacuum chamber system attach all the instrumentation

needed (Vacuum pump deposition meter and voltmeter) and use it to apply AR coating to a laser diode

After we have accomplished the AR coating other team will be in charge of designing the BEC apparatus

and use the results of our research

78

42 Experimentrsquos Equipment

421 Vacuum Chamber

For this research we designed a vacuum chamber whose main body is shown in figure 4-2 Its

dimensions are

Width 240 mm

Length 240 mm

Height 200 mm

Outer Diameter 4 in

Inner Diameter 15 in

Fig 4-2 Vacuum Chamber Main Body

The chamber is made up of 6 pass ways pass way A is the connection with the Laser Deposition

Equipment pass way B is the connection with the Turbo Pump and pass way C is for the connection with

the Deposition Source

A

C

B

79

Pass way C is for the deposition source as mentioned above This is a system where a thermal

resistance is heated by passing a high current through it which heats up a filament boat (made of tungsten)

where the material to be evaporated is place We control the temperature as such that the material will

evaporate and the heat will not cause the filament boat to crack

Because P = Isup2 R (where P is power I is current and R is resistance) to avoid the current to flow

where it is not desired we decided that the material for the Thermocouple shown in figure 4-3 should be

Copper ᴓ 63 mm We choose it that way because Copper has very good heat dissipation characteristics

and the resistance value is low It can reduce the value of the current enough to make the thermocouple to

create heat

Fig 4-3 Thermocouple

To the thermocouple we attach the tungsten filament boat We need to take notice of materials to be

used in this design because when using high current the tungsten filament boar will heat up and so the

material must be able to keep up with the heating potential of tungsten and has a low coefficient of heat

dissipation to avoid the tungsten to fail when heating up and therefore not evaporating Considering all

this we decide to use Stainless Steel

Because this clamp will be assembled inside the chamber after many revisions it was determined it

will have the shape shown in figure 4-4

Fig 4-4 Filament Boat Clamp Design

80

For the tungsten filament boat we bought the product from a distributor The dimensions are

Length 100 mm

Width 10 mm

Height 1 mm

Our thermocouple is 15 in but the pass way C is 4 in so we need to attach a Flange that connects

15in to 4in Because these specifications are quite difficult to achieve by Milling we had to use

electrical wire cutting

For the laser clamping system where the laser that is going to be AR coated will be placed will be

connected to pass way A the assembly is shown in figure 4-5 below

Fig 4-5 Cover Assembly

For this design we used an O-ring instead of a gasket so as to save time The design of the assembly

where the laser will be placed is shown in figure 4-6

Fig 4-6 Upper Cover Inner Assembly

D

E

F

81

Point D is the plate in the assembly where the laser diode will be fixed Because of the easy

processing we decide to use Aluminum and it is screwed to the top cover Point E is the connection for

the Quartz crystal resonator and it is designed in the same as point F in this way the results of the quartz

microbalance system will be more accurate in real time Point F is the final resting place for the laser

diode We use a Thor Labs Base with dimensions of ᴓ 9mm and ᴓ 56mm for two different size laser

diodes It just needs to be plugged in for easy installation

From figure 4-6 we know that the system needs signal system connections and because of the

change in temperature inside the chamber this could affect the functioning of the quartz microbalance so

we also need to install water tubes for cooling This is shown in figure 4-7 below

Fig 4-7 Diagram of Upper Cover Connections

In figure 4-8 we show the Feed through connections and their functions

Fig 4-8 Feed through Diagram

82

1 SQM-160 wire 5 Laser Connection 1 (Vin)

2 SQM-160 (G) 6 Laser Connection 2 (G)

3 K-Type-1 7 Laser Connection 3 (PD)

4 K-Type-2 8 Not In Use

The fully assembled chamber is shown in figure 4-9

Fig 4-9 Fully Assembled Chamber

422 Quartz Crystal Microbalance

For measuring the deposition on our target for coating we used the Inficon SQM-160 RateThickness

Monitor It is an easy to use instrument for measuring many types of thin-film coatings as shown in

figure 4-10

(a) Front Panel (b) Back Panel

Fig 4-10 Inficon SQM-160

83

Table 4-1 shows the technical specifications for this equipment

Number of sensors 2 Standard 4 additional optional

Sensor Frequency Range 40 MHz ~ 60 MHz

Reference Frequency Accuracy 002

Thickness Display Resolution 1 Aring

Thickness Resolution 015 Aring (Std) 0037 Aring (Hi Res)

Density of Stored Films 05-9999 gmcc

Tooling 10-399

Z-Factor 010-1000

Final Thickness 0000-9999k Aring

Measurement Period 15 to 2 sec

Simulation Mode Yes

Frequency Mode Yes

Rate Resolution 011 Arings

Dual Crystal Yes

Etch Mode Yes

Crystal Tooling 10-399

Crystal Fail Min Max 40 to 60 MHz 41 to 61 MHz

Power 100-120 200-240~plusmn10 nominal 20W

Operation Environment 0degC ~ 50degC

0 ~ 80 RH non-condensing

0 ~ 2000 meters

Class 1 Equipment

Pollution Degree 2

Rack Dimensions 885mm x 2127mm x 1969mm

Weight 27 kg

Table 4-1 Inficon SQM-160 RateThickness Monitor Specs

84

To the SQM-160 we need to connect an Oscillator We use the Sigma Instruments Remote Oscillator

Ser No 2 268 as shown in figure 4-11

Fig 4-11 Sigma Instruments Remote Oscillator

The connections diagram is shown in figure 4-12

Fig 4-12 SQM-160 Connections Diagram

85

423 Turbo Pump

For our experiments we used the Pfeiffer TCP 015 Electronic Drive Unit shown below in figure 4-13

Table 4-2 shows the technical specifications for this equipment

(a) Front Panel (b) Back Panel

Fig 4-13 Pfeiffer TCP 015 Electronic Drive

Connection Voltage (100V) 90-112

Mains Frequency 5060 Hz

Start-up Current 22 A

Nominal Frequency 1500 Hz

Rotation Speed 10V = 1500Hz plusmn2

Analog Output Current 10 V = 25 A plusmn 5

Rotation Speed Switchpoint 750 Hz

Works Setting 8 min

Permissible Ambient Temperature 0degC ~ 40degC

Dimensions Front Panel 1285mm x 1063mm

Insertion Length 227mm

Weight 27 Kg

Table 4-2 Pfeiffer TCP 015 Electronic Drive Specs

86

The connections diagram is shown in figure 4-14

Fig 4-14Connections Diagram for Pfeiffer TCP 015

To measure the pressure inside the chamber we use the Granville Phillips 375 Convectron Vacuum

Pressure Controller shown in figure 4-15

(a) Front Panel (b) Back Panel

Fig 4-15 Granville Phillips 375 Convectron

87

Its dimensions are shown in figure 4-16

Fig 4-16 Dimensions of Convectron

Table 4-3 shows the technical specifications for this equipment

Table 4-3 Granville Phillips 375 Convectron Vacuum Pressure Controller Specs

88

424 Multimeter

For our experiment we used the Keithley 2000 Digital Multimeter as shown in figure 4-17

(a) Front Panel (b) Back Panel

Fig 4-17 Keithley Model 2000 6-12-Digit Digital Multimeter

Its technical specifications are shown in table 4-4

Table 4-4 Keithley Model 2000 6-12-Digit Digital Multimeter Specs

89

43 Experiment Procedure

1 Connecting together the equipment and the chamber

(1) We first connect the resonator to the thickness monitor and connect the other side to the

chamber

(2) We now connect the flexible tubes to the turbo pump on one side and to the chamber on the

other

(3) We need to check that tubes are tightly connected to avoid any leaks in the vacuum pumping

process which will not allow us to get to our goal of Torr As shown in figure 4-18

(4) Connect the convectron to the system as shown in figure 4-19

Fig 4-18 checking for leaks using alcohol

Fig 4-19 Convectron attached to System

90

(5) Attach the clamps of the Multimeter to the bottom of the chamber as shown in figure 4-20

(6) Place the Quartz crystal in place

(7) Close tight vacuum chamber

(8) Connect all electrical appliances to power source

Fig 4-20 Multimeter Connections

2 Starting up the System

(1) We turn on all the devices as such Check all systems are ready to function Reset all values

that might be left over from previous tests

(2) Start the thickness monitor and set all values for this experiment In our case we got to testing

the system but not actual coating So we used the simulation mode of the thickness monitor as

shown in figure 4-21

Fig 4-21 Simulation Mode

91

(3) Start the turbo pump Make sure the lid on the vacuum chamber is tightly closed

(4) Start convectron and record initial pressure

(5) Start Multimeter and record initial current

3 Coating Process

(1) If we have the deposition material inside the filament boat the power source for the high

current must be started as well

(2) Record all initial values for thickness current pressure

(3) For an ideal experiment we need a thickness of around 101 nm a pressure of Torr and

a current of 300 A

44 Results

From previous experiments we have shown that we can turn a LED into a laser by means of AR

Coating In figure 4-22 shown below we can compare the actual results of a Diode before and after AR

coating From the blue line we can see that when the diode is at a current of 15mA its light will change

from LED to laser and if we look at the red line its critical current is around 30 to 35 mA

Fig 4-22 AR Coating Comparison for Laser Diodes

This means that the light emitted is not as strong as if the diode had been coated because inside the

chamber there must be some excitation first so the reflectivity of both sides inside the diode must be high

So because of the coating in one of the sides we have opened a door and let the light come out so the

critical current is risen as such and will be higher value than that of before the coating

92

In the following figures we can see the difference between before and after coating in a material The

thickness is around 1016 nm for this material

Fig 4-23 Before Coating

Fig 4-24 After Coating

93

Chapter 5 CONCLUSIONS AND RECOMMENDATIONS

51 Conclusions

For the first part of this independent study taking into consideration the data that came out of our

research and that sent by the provider we can say

1 SUM 23 after heat treatment will unexpectedly develop cracking in the middle of the tensile

testing process and suddenly break

2 Itrsquos possible that in the process of heat treatment to the SUM 23 material the treatment was not

uniform and this will create a pre-loaded moment force on one side that pushes on the other side

of the specimen resulting in material deformation

3 In the process of attaching the strain gauges to the materials it is very easy to make errors due to

poor adhesion or sudden removal in the tensile testing process

For our second part of the independent study the following can be made

1 At the beginning of this independent study we had no idea what Bose-Einstein Condensate was

or what was its purpose After much literature we finally comprehended the basic principles to

put into practice for our research

2 Our systemrsquos basic working principles and equipmentrsquos complexity are a little difficult to grasp

but hopefully we were able to understand enough of it

3 Theoretically from relation between the power and current we can know the advantages and

disadvantages of AR Coating

4 We were able to assemble the system and run test on its functions Even though we were able to

do this there is still much more work left to do with this system

52 Recommendations

For the Tensile Testing the following can be said

1 Ask the provider to check on the process of heat treatment on the SUM 23 material and give

them the information we have gathered through our test so they can correct for the mechanical

properties found if any change is needed

2 To avoid the problem of the inaccuracy of the poor adhesion of strain gauges we can attach

multiple strain gauges to the same one specimen so as to correlate data and improve our results

For the AR Coating the following can be said

1 We need to make sure that there are no physical defects on the main body of the chamber so as to

achieve maximum efficiency in the vacuum process If there was then the vacuum will arrive to

certain point and then start to decrease

2 It would be preferable to add some sort of visual aid that will allow the user to check the inside of

the chamber without actually opening it This will help us determine at what times we should

manipulate the current to better evaporate the substrate

94

REFERENCES

[1] A L Window Strain Gauge Technology Elsevier Applied Science London and New York 2nd

Edition 1992

[2] CC Perry and HR Lissner Strain Gauge Primer McGraw-Hill Book Co Inc New York 1955

[3] James W Dally William F Riley McGraw-Hill 1978

[4] University of Colorado Boulder BEC - What is it and where did the idea come from

httpwwwcoloradoeduphysics2000becwhat_is_ithtml

[5] Ultraslow Light amp Bose-Einstein Condensates Two-way Control with Coherent Light amp Atom

Fields Harvard Hau Lab Dr Lene Vestergaard Hau Optics amp Photonics News 16 1995

[6] The Art of Taming Light Ultra-slow and Stopped Light Harvard Hau Lab Dr Lene

Vestergaard Hau Europhysics News 2004

[7] Nonlinear Optics Shocking Superfluids Harvard Hau Lab Dr Lene Vestergaard Hau Nature

Physics 2007

[8] Model P3 Strain Indicator and Recorder Instruction Manual Vishay Micro-Measurements 2005

[9] Granville-Phillips Series 375 Convectron Vacuum Gauge Controller Instruction Manual Brooks

Automation 2008

[10] Effect of Film Thickness on the Validity of the Sauerbrey Equation for Hydrated Polyelectrolyte

Films Vogt Lin Wu White 2004

[11] Quartz Crystal Microbalance Study of DNA Immobilization and Hybridization for DNA Sensor

Development Chang Zhao 2008

[12] Installation of Strain Gages with SR-4 PrecoatAdhesive Vishay Micro-Measurements 2005

[13] Strain Gauge Measurement ndash A Tutorial National Instruments 1998

[14] Correlation between Vickers Hardness Number and Yield Stress of Cold-Formed Products

Yavuz Tekkaya

[15] httpsenwikipediaorg

Page 36: PC Hinge Materials Testing and AR Laser Diode Coating

36

Table 2-2 Continued

37

Table 2-2 Continued

38

Table 2-2 Continued

235 Vacuum Chamber System

Vacuum Evaporation is the process of depositing thin films of materials onto surfaces The technique

consists of pumping a vacuum chamber to pressures of less than torr and heating a material to

produce a flux of vapor in order to deposit the material onto a surface The material to be vaporized is

typically heated until its vapor pressure is high enough to produce a flux several Angstrom per second by

using an electrically resistive heater or bombardment by a high voltage beam The process was invented

by Henri Nestle in 1886 for food industry

In here the system has been pumped to a vacuum of Torr When a high current is passed

through the filament boat the filament boat is heated over the desired metal evaporation temperature and

so evaporation starts When the evaporation process is finished and the metal cools down crystals

condensate in the surface of the wafer From the weight of the evaporated material the distance between

the filament boat and the wafer we are able to calculate the deposition thickness and we can also use the

mass detector follower like the Quartz crystal resonator microbalance system In the process of

evaporation we usually use a board in between the filament boat and the wafer This is because before we

arrive to the desired evaporation temperature there will be some impurities that will be vaporized in the

controlled environment so we first use a small current and the board in between to get rid of those

impurities and this raises the purity of the deposition material

39

A vacuum evaporation system is shown in figure 2-24

Fig 2-24 Vacuum Evaporation System

Rough Vacuum 760 ~ 1 torr

Medium Vacuum 1 ~ torr

High Vacuum ~ torr

Ultra-High Vacuum Lower than torr

Table 2-3 Classification of Vacuum

For our study we need to use a Turbo Pump A regular turbo pump is shown in figure 2-25

Fig 2-25 Turbo Pump

For our research we used the Pfeiffer TCP 015 Electronic Drive Unit and Granville Phillips 375

Convectron shown below in figure 2-26

40

Fig 2-26 Control and Measurement Equipment

The electronic drive controls the turbo pump and the Convectron measures the pressure inside our

chamber The turbo pump is a type of vacuum pump used to maintain high vacuum Most turbo pumps

are centrifugal When we start the pumping we need to use a mechanical pump so as to decrease the

pressure inside the system from constant atmospheric pressure to torr and then the use dispersion

pump to continue the vacuum until we get to the desired pressure We need to notice though when we

start the dispersion pump we canrsquot turn off the mechanical pump and they both need to run together If

we need to turn off the pumping we first turn off the dispersion pump wait for it to completely stop and

then turn off the mechanical pump

Our completely assembled system is shown in figure 2-27 below

Fig 2-27 Complete System

41

Chapter 3 TENSILE TESTING IN DEPTH

31 Experimentrsquos Purpose and Principles

By means of Universal testing machine and Strain gauges we were able to observe discuss and

analyze the phenomena created when a specimen of certain material is manipulated under an external load

and determine the stress strain and deformation values later we can use the graphing methods of

stress-strain diagram to describe it

The main point of this experiment is that after the tensile specimen is tested use computer analysis

and the actual strain data and after statistical adjustment make the final results report (Tensile testing

experiment is in accordance with ASTM E8)

32 Experimentrsquos Equipment

321 Universal Testing Machine

For the materials testing experiment part of this research we use a Universal Testing Machine as

shown in figure 31 The maximum load it can apply is 100 Ton After the test specimen is secured on the

device with the use of instrumentation the load exerted and the effects of this become apparent on the

specimen and even the smallest of changes can be recorded For our research we used the Chun Yen

Testing Machines Co Ltd 100 Ton Micro Computer Universal Tensile Tester

Fig 31 Universal Testing Machine

42

Table 31 shows the specifications for this machine

Max Capacity 100 Ton

Accuracy plusmn1

Tension (mm) Max Space 1150mm

Grip for Rod 20-70mm

Ram Stroke 250mm

Effective Column Interval 940mm

Crosshead Speed 300mmmin

Testing Speed 0-50mmmin

Volume of Machine 1700times1000times3350mm(LtimesWtimesH)

Volume of Control Panel 1000times800times1500mm(LtimesWtimesH)

Weight 8000kg

Power 3∮220V 20A

Computer AMD K6-2-350

OS Windows XP

Screen 15rdquo CRT

Table 3-1 Chun Yen Testing Machine Specs Table

The connections diagram is shown in figure 3-2

Fig 3-2 Diagram for System Connections

43

When the test specimen is placed when the external force is applied the Load Cell can measure the

size of the applied force and the Encoder measures the expansion rate of change The Local Controller

receives all the information from the 2 units after arranging the results they are displayed in the

computer and they can be afterwards submitted for more complex analysis such as Finite Element

Analysis and we can get the Stress-Strain Diagram

322 Strain Measurement Equipment

The equipment used in our research provides a four-channel measurement that means we can use up

to 4 strain gauges at a time to do our measurements and provides 3 different bridge arrangements as

shown in figure 3-3

(a) (b) (c)

Fig 3-3 Input Connections for Strain Indicator

Figure 3-3 (a) is the Quarter Bridge (b) is the Half Bridge and (c) is the Full Bridge and Transducers

For our study we used the Quarter Bridge and use the Strain Gauge values to decide the position of the

connecting wires The Strain indicator is shown in figure 3-4

Fig 3-4 Vishay Micro-Measurements Model P3 Strain Indicator and Recorder

44

Input Connections Tool Free eccentric lever release

4-channel input

Wire diameter16-28AWG

Bridge Configurations Quarter- Half- and Full Bridge

Bridge Impedance 60-2000Ω

Display 128 64 pixel FSTN positive gray LCD

Data Conversion AD Converter filter

Measurement Range Resolution Strain Range plusmn155mVV

Resolution plusmn00005mVV

Measurement Accuracy plusmn01 of reading plusmn3 counts

Gage Factor Control 0500-9900

Balance Control Software either manual or automatic

Bridge Excitation 15VDC nominal

Communication Interface USB Cable Included

Data Storage Removable Media Card

Shunt Calibration Across bridge completion resistors controlled

by software When Gage Factor=200

120Ω350Ω1000Ω

Analog Output Value 0 to 25V max

Ranges plusmn320 microε plusmn3200 microε plusmn32000 microε

Error 05 output voltage +5mV

Max Error 14 output voltage + 20mV

Update rate 480 samplessec

Output Load 2000Ω

Power Battery Two Alkaline D cells

Battery life 400 hours typ

USB 5V 100mA

Operational Environment Temperature 0-50

Humidity Up to 90 Non-condensing

Case Aluminum Alloy

Size and Weight 228times152times152(mm) 20(kg)

Table 3-2 Vishay Micro-Measurements Model P3 Strain Indicator and Recorder Specs

45

323 Strain Gauge

The strain gaugersquos main basic principle is to use a resistancersquos characteristics to measure the strain

The inside connections of the strain indicator are shown in figure 3-5

Fig 3-5 Inner Connections

As shown above this is a quarter-bridge connection We connect equal-length 3 wires to the 2

connections allowed by the strain gauge wire 1 and 3 can be used to cancel out the effects of temperature

to the resistance and because of the addition of wires 1 and 3 wire 2 can directly measure the experiment

results from the strain gauge and therefore the strain developed with no influence of temperature

If there were no two measuring leads then the relations will be

R 4 =R g +2R L

Where Rg is the Strain Gauge Value and RL is the wire resistance then

4

4

R

R=

Lg

g

RR

R

2

=

gL

gg

RR

RR

21

amp

4

4

R

R=

g

g

R

R(1- L)

Where L is the Signal Loss Factor and so

L =gL

gL

RR

RR

21

2

g

L

R

2R if

g

L

R

2Rltlt1

46

(Actual Value R g =120R L =08g

L

R

2Ris always much smaller than 1)

R 4 =R g +2R LR 2 =R 3 =rR gR 1 =R g 32 RR =0

V 0 =V 2)1( r

r

(

4

4

R

R-

1

1

R

R)

The first term describes loss attenuation effects second term describes loss of balancing capabilities

effects

V 0 =V 2)1( r

r

[

)2

(Lg

g

RR

R

+

T

Lg

g

RR

R

)

2( + T

Lg

L

RR

R

)

2

2( -(

g

g

R

R) T ]

The first term describes loss attenuation effects and loss of balancing capabilities effects the second

third and fourth terms describe the temperature effects on the wire

For the three-wire method we have

L =gL

gL

RR

RR

1

g

L

R

R if

g

L

R

Rltlt1

V 0 =V 2)1( r

r

[

)(Lg

g

RR

R

+

T

Lg

g

RR

R

)( + T

Lg

L

RR

R

)

2( -

T

Lg

g

RR

R

)( - T

Lg

L

RR

R

)

2( ]

V 0 = V2)1( r

r

)(

Lg

g

RR

R

In the last four terms inside parenthesis we can see the effects of temperature being cancelled out and the

effect on first term is not great so this is the reason why in our research we use three wires

47

324 Specimen Measurements

The tensile specimens used in this research are compliant of ASTM E8 Tensile parameters as shown

in figure 3-6

Fig 3-6 Tensile Specimen

Diameter

D(mm)

Gauge

Length

G(mm)

Smallest

Arc

Radius

R(mm)

Shortest

Area

A(mm)

Total

Length

L(mm)

Clamping

Area

Length

B(mm)

Clamping

Area

Diameter

C(mm)

Bar 125 02 625 01 gt10 gt75 ~ 145 ~ 35 20

Table 3-3 Specifications for Round Bar

33 Experiment Procedure

1 Attaching the Strain Gauge to the Tensile Specimen

(1) Prepare 1 ASTM E8 compliant tensile specimen round bar as shown in figure 3-7

(2) Prepare Strain Gauge as those described in table 3-4

(3) Prepare other consumables and adhesive agent such as epoxy adhesive or

cyanoacrylate adhesive as shown in figure 3-8

48

Fig 3-7 Actual Tensile Specimen

Fig 3-8 Other Materials Used (Such as Alcohol gauze transparent tape adhesive)

Gage Type

EA-06-120LZ-120E

Resistance in ohms at 24∘C

1200plusmn03

Gage Factor at 24∘C

2075plusmn05

Transverse Sensitivity at 24∘C

(+07plusmn02)

Table 3-4 Specifications for Strain Gauge

2 Attaching Strain Gauge

As shown in following figures we shall explain the attachment of the strain gauge

(1) Use sand paper and a rasp to clean thoroughly the surface where the strain gauge will be

attached to

49

(a)

(2) Use alcohol to wash the surface where the strain gauge will be attached and use gauze to rub

it off

(b)

(3) Find a clean surface and clean it with alcohol and gauze

(c)

(4) Place the strain gauge in the clean surface Use a piece of transparent tape on top of the strain

gauge after securely placed rip it off the surface carefully

50

(d)

(5) Use a piece of white paper to mark the place where the strain gauge will be attached and in

this way we can make sure that the strain gauge will be placed as horizontally and vertically

correct as possible

(e)

(6) In the place where we had our mark place the strain gauge

(f)

(7) Carefully lift one side of the tape and apply some of the adhesive agent to both the strain

gauge and specimenrsquos surface

(g)

51

(8) We need to make sure that the gauge and the specimen will be firmly attached so we gently

apply pressure with our thumb

(h)

(9) After the adhesive is fully dry we can carefully rip off the tape

(i)

(10) We need to do the whole process twice one for the horizontally placed strain gauge and one

for the vertically placed strain gauge

52

(j)

(11) We now proceed to solder the wires to the strain gauge

(k)

(12) After soldering we use a Volt Multimeter to measure that there is no contact between wires

If there is none then the specimen is ready for testing

(l)

(13) We now need to measure a 5cm distance and mark it to check and compare the elongation

before and after the tensile testing

(m)

53

Fig 3-9 Specimen-Strain Gauge Process

3 Tensile Test

(1) Enter the computer application that controls the tensile testing machine

(2) Turn on the tensile testing machine main switch

(3) Adjust the hydraulic pump to go back to its original position

(4) Bring the lowering motor down to a distance enough so as to attach the tensile specimen to the

system open the clamps and secure the specimen

(a)

(5) Connect all the necessary wires to the strain indicator equipment

54

(b)

(6) Start the ascending motor and wait for the expansion

(c)

Fig 3-10 Specimen-Tensile Testing Process

4 Start the Test

(1) Enter the software application and enter some variables needed for the experiment in the

specific screen

(2) Go back to the main screen and press the [測試] (measure) button to start the test and auto

recording in the software

(3) After the specimen breaks the mechanical device will automatically stop and ask the user to

enter the total displacement We take out the specimen from the testing machine and adjust the

machinersquos position back to its original position

(4) Save the results information

(5) Record the results from the strain indicator

34 Results

From this experiment we can get the Poissonrsquos Ratio Youngrsquos Modulus and Yield Strength etc and

because of the slippage phenomenon in the clamp at the moment of the test then the Elastic Limit will

display some yield phenomena So omit any undesirable results we just take the Yield portion of the

results as reference

In the process of the experiment the most important part to attend to is the attaching of the strain

gauge because the gaugersquos purpose is to measure the strain developed during the test and this strain

might be very small If the gaugersquos angle change during the test ie is not well attached this will affect

the accuracy of the measurements of Poissonrsquos ratio and Youngrsquos modulus

55

The materials provided by the manufacturer are SUM 23 and SUM 43 steel round bars and these two

types of materials have been through different heat treatment processes so they can be sub-divided

further into untreated material heat-treated material and black surface heat treated material for the two

materials with heat treatment the treatment process and finished are different In the end we only have

the mechanical properties that were calculated after our research of these materials

All of the specifications are identical to those shown in figure 3-6

341 SUM 23

Fig 3-11 SUM 23 Untreated Material

Number 7 10

Hardness(HRB) 74 75

Yield Stress (MPa) 448 440

Tensile Strength (MPa) 544 560

Poissonrsquos Ratio 029 027

Youngrsquos Modulus (GPa) 203 210

Cut-off Area Shrinking () 42 41

Elongation () 1125 1011

Table 3-5 Mechanical Properties of SUM 23 Untreated

56

Stress-Strain Diagram

(a)

(b)

57

Fig 3-12 Stress-Strain Diagrams for (a) 7 Round Bar and (b) 10 Round Bar

Cut-Off Area

(a)

(b)

Fig 3-13 Cut-Off Area of (a) 7 Round Bar and (b) 10 Round Bar

58

SUM 23 Nickel Round Bar

Fig 3-14 SUM 23 Nickel Material

Number 1 2 3 4

Hardness(HRB) 48 50 49 48

Yield Stress (MPa) 370 370 380 400

Tensile Strength (MPa) 455 451 450 450

Poissonrsquos Ratio 028 046 029 026

Youngrsquos Modulus (GPa) 243 303 246 206

Cut-off Area Shrinking () 803 803 726 601

Elongation () 566 65 602 647

Table 3-6 Mechanical Properties of SUM 23 Nickel

59

Stress-Strain Diagram

(a)

60

(b)

(c)

(d)

61

Fig 3-15 Stress-Strain Diagrams for (a) 1 Round Bar (b) 2 Round Bar (c) 3 Round Bar and (d)

4 Round Bar

Cut-Off Area

(a)

(b)

62

(c)

(d)

Fig 3-16 Cut-Off Area of (a) 1 Round Bar (b) 2 Round Bar (c) 3 Round Bar and (d) 4 Round

Bar

63

SUM 23 Black Surface Round Bar

Fig 3-17 SUM 23 Black Surface Material

Number 1 2 3

Hardness(HRB) 51 50 51

Yield Stress (MPa) 378 371 369

Tensile Strength (MPa) 467 465 464

Poissonrsquos Ratio 03 016 04

Youngrsquos Modulus (GPa) 215 266 266

Cut-off Area Shrinking () 986 94 848

Elongation () 748 805 761

Table 3-7 Mechanical Properties of SUM 23 Black Surface Material

64

Stress-Strain Diagram

(a)

(b)

65

(c)

Fig 3-18 Stress-Strain Diagrams for (a) 1 Round Bar 2 Round Bar and (c) 3 Round Bar

Cut-Off Surface

(a)

66

(b)

(c)

Fig 3-19 Cut-Off Surface of (a) 1 Round Bar 2 Round Bar and (c) 3 Round Bar

67

342 SUM 43

Fig 3-20 Untreated SUM 43 Untreated Material

Number 1 5

Hardness(HRB) 76 75

Yield Stress (MPa) 572 594

Tensile Strength (MPa) 743 785

Poissonrsquos Ratio 027 029

Youngrsquos Modulus (GPa) 200 202

Cut-off Area Shrinking () 338 2944

Elongation () 857 894

Table 3-8 Mechanical Properties of SUM 43 Untreated

68

Stress-Strain Diagrams

(a)

(b)

Fig 3-21 Stress-Strain Diagrams for SUM 43 (a) 1 Round Bar and (b) 5 Round Bar

69

Cut-Off Area

(a)

(b)

Fig 3-22 Cut-Off Area of SUM 43 (a) 1 Round Bar and (b) 5 Round Bar

70

SUM 43 Nickel Round Bar

Fig 3-23 SUM 43 Nickel Material

Number 4 5

Hardness(HRB) 51 50

Yield Stress (MPa) 1580 1544

Tensile Strength (MPa) 1639 1625

Poissonrsquos Ratio 03 028

Youngrsquos Modulus (GPa) 194 201

Cut-off Area Shrinking () 1697 137

Elongation () 376 265

Table 3-9 Mechanical Properties of SUM 43 Nickel

71

Stress-Strain Diagrams

(a)

(b)

Fig 3-24 Stress-Strain Diagrams for (a) 4 Round Bar and (b) 5 Round Bar

72

Cut-Off Area

(a)

(b)

Fig 3-25 Cut-Off Area of (a) 4 Round Bar and (b) 5 Round Bar

73

SUM 43 Black Surface Material

Fig 3-26 SUM 43 Black Surface Material

Number 3 5

Hardness(HRB) 56 56

Yield Stress (MPa) 1416 1361

Tensile Strength (MPa) 1591 1402

Poissonrsquos Ratio 029 031

Youngrsquos Modulus (GPa) 200 202

Cut-off Area Shrinking () 139 124

Elongation () 24 24

Table 3-10 Mechanical Properties of SUM 43 Black Surface Material

74

Stress-Strain Diagrams

0 2 4 6 8 10 12 14

-200

0

200

400

600

800

1000

1200

1400

1600

1800

應力 (MPa)

應變()

(a)

0 2 4 6 8 10

-200

0

200

400

600

800

1000

1200

1400

1600

應力

(MPa)

位移 ()

(b)

Fig 3-27 Stress-Strain Diagrams for (a) 3 Round Bar and (b) 5 Round Bar

(Note These curves were formulated using Visual Solutions Inc VisSim Software)

75

Cut-Off Area

(a)

(b)

Fig 3-28 Cut-Off Area of (a) 3 Round Bar and (b) 5 Round Bar

76

The force value (N) was retrieved from the Universal Testing Machine

The Poissonrsquos Ratio (ε) is calculated as

ε =

the values for the Poissonrsquos Ratio are in average around 0297

The Youngrsquos Modulus (E) is calculated as

E =

Where

Stress =

Cross-sectional Area =

where D is the Diameter

The value for D was in average around 1258 mm

The values shown by the computer because there is Slippage phenomena between the Clamp and the

specimen will not be taken into consideration for the elongation strain and Youngrsquos modulus and we will

refer to the values that we have meticulously calculated

77

Chapter 4 AR COATING IN DEPTH

41 Experimentrsquos Purpose and Principles

By means of a vacuum chamber and several other instruments we intend to apply Anti-Reflective

Coating using deposition process to a laser diode and in this way reduce its refraction so as to make it

lose less light in the process of amplification and we can control certain wavelengths we want produced

for certain desired applications in our case we are attempting to re-create a Bose-Einstein Condensate

An optimal BEC apparatus is shown in figure 4-1

Fig 4-1 BEC Apparatus

The main point of this experiment is to build a vacuum chamber system attach all the instrumentation

needed (Vacuum pump deposition meter and voltmeter) and use it to apply AR coating to a laser diode

After we have accomplished the AR coating other team will be in charge of designing the BEC apparatus

and use the results of our research

78

42 Experimentrsquos Equipment

421 Vacuum Chamber

For this research we designed a vacuum chamber whose main body is shown in figure 4-2 Its

dimensions are

Width 240 mm

Length 240 mm

Height 200 mm

Outer Diameter 4 in

Inner Diameter 15 in

Fig 4-2 Vacuum Chamber Main Body

The chamber is made up of 6 pass ways pass way A is the connection with the Laser Deposition

Equipment pass way B is the connection with the Turbo Pump and pass way C is for the connection with

the Deposition Source

A

C

B

79

Pass way C is for the deposition source as mentioned above This is a system where a thermal

resistance is heated by passing a high current through it which heats up a filament boat (made of tungsten)

where the material to be evaporated is place We control the temperature as such that the material will

evaporate and the heat will not cause the filament boat to crack

Because P = Isup2 R (where P is power I is current and R is resistance) to avoid the current to flow

where it is not desired we decided that the material for the Thermocouple shown in figure 4-3 should be

Copper ᴓ 63 mm We choose it that way because Copper has very good heat dissipation characteristics

and the resistance value is low It can reduce the value of the current enough to make the thermocouple to

create heat

Fig 4-3 Thermocouple

To the thermocouple we attach the tungsten filament boat We need to take notice of materials to be

used in this design because when using high current the tungsten filament boar will heat up and so the

material must be able to keep up with the heating potential of tungsten and has a low coefficient of heat

dissipation to avoid the tungsten to fail when heating up and therefore not evaporating Considering all

this we decide to use Stainless Steel

Because this clamp will be assembled inside the chamber after many revisions it was determined it

will have the shape shown in figure 4-4

Fig 4-4 Filament Boat Clamp Design

80

For the tungsten filament boat we bought the product from a distributor The dimensions are

Length 100 mm

Width 10 mm

Height 1 mm

Our thermocouple is 15 in but the pass way C is 4 in so we need to attach a Flange that connects

15in to 4in Because these specifications are quite difficult to achieve by Milling we had to use

electrical wire cutting

For the laser clamping system where the laser that is going to be AR coated will be placed will be

connected to pass way A the assembly is shown in figure 4-5 below

Fig 4-5 Cover Assembly

For this design we used an O-ring instead of a gasket so as to save time The design of the assembly

where the laser will be placed is shown in figure 4-6

Fig 4-6 Upper Cover Inner Assembly

D

E

F

81

Point D is the plate in the assembly where the laser diode will be fixed Because of the easy

processing we decide to use Aluminum and it is screwed to the top cover Point E is the connection for

the Quartz crystal resonator and it is designed in the same as point F in this way the results of the quartz

microbalance system will be more accurate in real time Point F is the final resting place for the laser

diode We use a Thor Labs Base with dimensions of ᴓ 9mm and ᴓ 56mm for two different size laser

diodes It just needs to be plugged in for easy installation

From figure 4-6 we know that the system needs signal system connections and because of the

change in temperature inside the chamber this could affect the functioning of the quartz microbalance so

we also need to install water tubes for cooling This is shown in figure 4-7 below

Fig 4-7 Diagram of Upper Cover Connections

In figure 4-8 we show the Feed through connections and their functions

Fig 4-8 Feed through Diagram

82

1 SQM-160 wire 5 Laser Connection 1 (Vin)

2 SQM-160 (G) 6 Laser Connection 2 (G)

3 K-Type-1 7 Laser Connection 3 (PD)

4 K-Type-2 8 Not In Use

The fully assembled chamber is shown in figure 4-9

Fig 4-9 Fully Assembled Chamber

422 Quartz Crystal Microbalance

For measuring the deposition on our target for coating we used the Inficon SQM-160 RateThickness

Monitor It is an easy to use instrument for measuring many types of thin-film coatings as shown in

figure 4-10

(a) Front Panel (b) Back Panel

Fig 4-10 Inficon SQM-160

83

Table 4-1 shows the technical specifications for this equipment

Number of sensors 2 Standard 4 additional optional

Sensor Frequency Range 40 MHz ~ 60 MHz

Reference Frequency Accuracy 002

Thickness Display Resolution 1 Aring

Thickness Resolution 015 Aring (Std) 0037 Aring (Hi Res)

Density of Stored Films 05-9999 gmcc

Tooling 10-399

Z-Factor 010-1000

Final Thickness 0000-9999k Aring

Measurement Period 15 to 2 sec

Simulation Mode Yes

Frequency Mode Yes

Rate Resolution 011 Arings

Dual Crystal Yes

Etch Mode Yes

Crystal Tooling 10-399

Crystal Fail Min Max 40 to 60 MHz 41 to 61 MHz

Power 100-120 200-240~plusmn10 nominal 20W

Operation Environment 0degC ~ 50degC

0 ~ 80 RH non-condensing

0 ~ 2000 meters

Class 1 Equipment

Pollution Degree 2

Rack Dimensions 885mm x 2127mm x 1969mm

Weight 27 kg

Table 4-1 Inficon SQM-160 RateThickness Monitor Specs

84

To the SQM-160 we need to connect an Oscillator We use the Sigma Instruments Remote Oscillator

Ser No 2 268 as shown in figure 4-11

Fig 4-11 Sigma Instruments Remote Oscillator

The connections diagram is shown in figure 4-12

Fig 4-12 SQM-160 Connections Diagram

85

423 Turbo Pump

For our experiments we used the Pfeiffer TCP 015 Electronic Drive Unit shown below in figure 4-13

Table 4-2 shows the technical specifications for this equipment

(a) Front Panel (b) Back Panel

Fig 4-13 Pfeiffer TCP 015 Electronic Drive

Connection Voltage (100V) 90-112

Mains Frequency 5060 Hz

Start-up Current 22 A

Nominal Frequency 1500 Hz

Rotation Speed 10V = 1500Hz plusmn2

Analog Output Current 10 V = 25 A plusmn 5

Rotation Speed Switchpoint 750 Hz

Works Setting 8 min

Permissible Ambient Temperature 0degC ~ 40degC

Dimensions Front Panel 1285mm x 1063mm

Insertion Length 227mm

Weight 27 Kg

Table 4-2 Pfeiffer TCP 015 Electronic Drive Specs

86

The connections diagram is shown in figure 4-14

Fig 4-14Connections Diagram for Pfeiffer TCP 015

To measure the pressure inside the chamber we use the Granville Phillips 375 Convectron Vacuum

Pressure Controller shown in figure 4-15

(a) Front Panel (b) Back Panel

Fig 4-15 Granville Phillips 375 Convectron

87

Its dimensions are shown in figure 4-16

Fig 4-16 Dimensions of Convectron

Table 4-3 shows the technical specifications for this equipment

Table 4-3 Granville Phillips 375 Convectron Vacuum Pressure Controller Specs

88

424 Multimeter

For our experiment we used the Keithley 2000 Digital Multimeter as shown in figure 4-17

(a) Front Panel (b) Back Panel

Fig 4-17 Keithley Model 2000 6-12-Digit Digital Multimeter

Its technical specifications are shown in table 4-4

Table 4-4 Keithley Model 2000 6-12-Digit Digital Multimeter Specs

89

43 Experiment Procedure

1 Connecting together the equipment and the chamber

(1) We first connect the resonator to the thickness monitor and connect the other side to the

chamber

(2) We now connect the flexible tubes to the turbo pump on one side and to the chamber on the

other

(3) We need to check that tubes are tightly connected to avoid any leaks in the vacuum pumping

process which will not allow us to get to our goal of Torr As shown in figure 4-18

(4) Connect the convectron to the system as shown in figure 4-19

Fig 4-18 checking for leaks using alcohol

Fig 4-19 Convectron attached to System

90

(5) Attach the clamps of the Multimeter to the bottom of the chamber as shown in figure 4-20

(6) Place the Quartz crystal in place

(7) Close tight vacuum chamber

(8) Connect all electrical appliances to power source

Fig 4-20 Multimeter Connections

2 Starting up the System

(1) We turn on all the devices as such Check all systems are ready to function Reset all values

that might be left over from previous tests

(2) Start the thickness monitor and set all values for this experiment In our case we got to testing

the system but not actual coating So we used the simulation mode of the thickness monitor as

shown in figure 4-21

Fig 4-21 Simulation Mode

91

(3) Start the turbo pump Make sure the lid on the vacuum chamber is tightly closed

(4) Start convectron and record initial pressure

(5) Start Multimeter and record initial current

3 Coating Process

(1) If we have the deposition material inside the filament boat the power source for the high

current must be started as well

(2) Record all initial values for thickness current pressure

(3) For an ideal experiment we need a thickness of around 101 nm a pressure of Torr and

a current of 300 A

44 Results

From previous experiments we have shown that we can turn a LED into a laser by means of AR

Coating In figure 4-22 shown below we can compare the actual results of a Diode before and after AR

coating From the blue line we can see that when the diode is at a current of 15mA its light will change

from LED to laser and if we look at the red line its critical current is around 30 to 35 mA

Fig 4-22 AR Coating Comparison for Laser Diodes

This means that the light emitted is not as strong as if the diode had been coated because inside the

chamber there must be some excitation first so the reflectivity of both sides inside the diode must be high

So because of the coating in one of the sides we have opened a door and let the light come out so the

critical current is risen as such and will be higher value than that of before the coating

92

In the following figures we can see the difference between before and after coating in a material The

thickness is around 1016 nm for this material

Fig 4-23 Before Coating

Fig 4-24 After Coating

93

Chapter 5 CONCLUSIONS AND RECOMMENDATIONS

51 Conclusions

For the first part of this independent study taking into consideration the data that came out of our

research and that sent by the provider we can say

1 SUM 23 after heat treatment will unexpectedly develop cracking in the middle of the tensile

testing process and suddenly break

2 Itrsquos possible that in the process of heat treatment to the SUM 23 material the treatment was not

uniform and this will create a pre-loaded moment force on one side that pushes on the other side

of the specimen resulting in material deformation

3 In the process of attaching the strain gauges to the materials it is very easy to make errors due to

poor adhesion or sudden removal in the tensile testing process

For our second part of the independent study the following can be made

1 At the beginning of this independent study we had no idea what Bose-Einstein Condensate was

or what was its purpose After much literature we finally comprehended the basic principles to

put into practice for our research

2 Our systemrsquos basic working principles and equipmentrsquos complexity are a little difficult to grasp

but hopefully we were able to understand enough of it

3 Theoretically from relation between the power and current we can know the advantages and

disadvantages of AR Coating

4 We were able to assemble the system and run test on its functions Even though we were able to

do this there is still much more work left to do with this system

52 Recommendations

For the Tensile Testing the following can be said

1 Ask the provider to check on the process of heat treatment on the SUM 23 material and give

them the information we have gathered through our test so they can correct for the mechanical

properties found if any change is needed

2 To avoid the problem of the inaccuracy of the poor adhesion of strain gauges we can attach

multiple strain gauges to the same one specimen so as to correlate data and improve our results

For the AR Coating the following can be said

1 We need to make sure that there are no physical defects on the main body of the chamber so as to

achieve maximum efficiency in the vacuum process If there was then the vacuum will arrive to

certain point and then start to decrease

2 It would be preferable to add some sort of visual aid that will allow the user to check the inside of

the chamber without actually opening it This will help us determine at what times we should

manipulate the current to better evaporate the substrate

94

REFERENCES

[1] A L Window Strain Gauge Technology Elsevier Applied Science London and New York 2nd

Edition 1992

[2] CC Perry and HR Lissner Strain Gauge Primer McGraw-Hill Book Co Inc New York 1955

[3] James W Dally William F Riley McGraw-Hill 1978

[4] University of Colorado Boulder BEC - What is it and where did the idea come from

httpwwwcoloradoeduphysics2000becwhat_is_ithtml

[5] Ultraslow Light amp Bose-Einstein Condensates Two-way Control with Coherent Light amp Atom

Fields Harvard Hau Lab Dr Lene Vestergaard Hau Optics amp Photonics News 16 1995

[6] The Art of Taming Light Ultra-slow and Stopped Light Harvard Hau Lab Dr Lene

Vestergaard Hau Europhysics News 2004

[7] Nonlinear Optics Shocking Superfluids Harvard Hau Lab Dr Lene Vestergaard Hau Nature

Physics 2007

[8] Model P3 Strain Indicator and Recorder Instruction Manual Vishay Micro-Measurements 2005

[9] Granville-Phillips Series 375 Convectron Vacuum Gauge Controller Instruction Manual Brooks

Automation 2008

[10] Effect of Film Thickness on the Validity of the Sauerbrey Equation for Hydrated Polyelectrolyte

Films Vogt Lin Wu White 2004

[11] Quartz Crystal Microbalance Study of DNA Immobilization and Hybridization for DNA Sensor

Development Chang Zhao 2008

[12] Installation of Strain Gages with SR-4 PrecoatAdhesive Vishay Micro-Measurements 2005

[13] Strain Gauge Measurement ndash A Tutorial National Instruments 1998

[14] Correlation between Vickers Hardness Number and Yield Stress of Cold-Formed Products

Yavuz Tekkaya

[15] httpsenwikipediaorg

Page 37: PC Hinge Materials Testing and AR Laser Diode Coating

37

Table 2-2 Continued

38

Table 2-2 Continued

235 Vacuum Chamber System

Vacuum Evaporation is the process of depositing thin films of materials onto surfaces The technique

consists of pumping a vacuum chamber to pressures of less than torr and heating a material to

produce a flux of vapor in order to deposit the material onto a surface The material to be vaporized is

typically heated until its vapor pressure is high enough to produce a flux several Angstrom per second by

using an electrically resistive heater or bombardment by a high voltage beam The process was invented

by Henri Nestle in 1886 for food industry

In here the system has been pumped to a vacuum of Torr When a high current is passed

through the filament boat the filament boat is heated over the desired metal evaporation temperature and

so evaporation starts When the evaporation process is finished and the metal cools down crystals

condensate in the surface of the wafer From the weight of the evaporated material the distance between

the filament boat and the wafer we are able to calculate the deposition thickness and we can also use the

mass detector follower like the Quartz crystal resonator microbalance system In the process of

evaporation we usually use a board in between the filament boat and the wafer This is because before we

arrive to the desired evaporation temperature there will be some impurities that will be vaporized in the

controlled environment so we first use a small current and the board in between to get rid of those

impurities and this raises the purity of the deposition material

39

A vacuum evaporation system is shown in figure 2-24

Fig 2-24 Vacuum Evaporation System

Rough Vacuum 760 ~ 1 torr

Medium Vacuum 1 ~ torr

High Vacuum ~ torr

Ultra-High Vacuum Lower than torr

Table 2-3 Classification of Vacuum

For our study we need to use a Turbo Pump A regular turbo pump is shown in figure 2-25

Fig 2-25 Turbo Pump

For our research we used the Pfeiffer TCP 015 Electronic Drive Unit and Granville Phillips 375

Convectron shown below in figure 2-26

40

Fig 2-26 Control and Measurement Equipment

The electronic drive controls the turbo pump and the Convectron measures the pressure inside our

chamber The turbo pump is a type of vacuum pump used to maintain high vacuum Most turbo pumps

are centrifugal When we start the pumping we need to use a mechanical pump so as to decrease the

pressure inside the system from constant atmospheric pressure to torr and then the use dispersion

pump to continue the vacuum until we get to the desired pressure We need to notice though when we

start the dispersion pump we canrsquot turn off the mechanical pump and they both need to run together If

we need to turn off the pumping we first turn off the dispersion pump wait for it to completely stop and

then turn off the mechanical pump

Our completely assembled system is shown in figure 2-27 below

Fig 2-27 Complete System

41

Chapter 3 TENSILE TESTING IN DEPTH

31 Experimentrsquos Purpose and Principles

By means of Universal testing machine and Strain gauges we were able to observe discuss and

analyze the phenomena created when a specimen of certain material is manipulated under an external load

and determine the stress strain and deformation values later we can use the graphing methods of

stress-strain diagram to describe it

The main point of this experiment is that after the tensile specimen is tested use computer analysis

and the actual strain data and after statistical adjustment make the final results report (Tensile testing

experiment is in accordance with ASTM E8)

32 Experimentrsquos Equipment

321 Universal Testing Machine

For the materials testing experiment part of this research we use a Universal Testing Machine as

shown in figure 31 The maximum load it can apply is 100 Ton After the test specimen is secured on the

device with the use of instrumentation the load exerted and the effects of this become apparent on the

specimen and even the smallest of changes can be recorded For our research we used the Chun Yen

Testing Machines Co Ltd 100 Ton Micro Computer Universal Tensile Tester

Fig 31 Universal Testing Machine

42

Table 31 shows the specifications for this machine

Max Capacity 100 Ton

Accuracy plusmn1

Tension (mm) Max Space 1150mm

Grip for Rod 20-70mm

Ram Stroke 250mm

Effective Column Interval 940mm

Crosshead Speed 300mmmin

Testing Speed 0-50mmmin

Volume of Machine 1700times1000times3350mm(LtimesWtimesH)

Volume of Control Panel 1000times800times1500mm(LtimesWtimesH)

Weight 8000kg

Power 3∮220V 20A

Computer AMD K6-2-350

OS Windows XP

Screen 15rdquo CRT

Table 3-1 Chun Yen Testing Machine Specs Table

The connections diagram is shown in figure 3-2

Fig 3-2 Diagram for System Connections

43

When the test specimen is placed when the external force is applied the Load Cell can measure the

size of the applied force and the Encoder measures the expansion rate of change The Local Controller

receives all the information from the 2 units after arranging the results they are displayed in the

computer and they can be afterwards submitted for more complex analysis such as Finite Element

Analysis and we can get the Stress-Strain Diagram

322 Strain Measurement Equipment

The equipment used in our research provides a four-channel measurement that means we can use up

to 4 strain gauges at a time to do our measurements and provides 3 different bridge arrangements as

shown in figure 3-3

(a) (b) (c)

Fig 3-3 Input Connections for Strain Indicator

Figure 3-3 (a) is the Quarter Bridge (b) is the Half Bridge and (c) is the Full Bridge and Transducers

For our study we used the Quarter Bridge and use the Strain Gauge values to decide the position of the

connecting wires The Strain indicator is shown in figure 3-4

Fig 3-4 Vishay Micro-Measurements Model P3 Strain Indicator and Recorder

44

Input Connections Tool Free eccentric lever release

4-channel input

Wire diameter16-28AWG

Bridge Configurations Quarter- Half- and Full Bridge

Bridge Impedance 60-2000Ω

Display 128 64 pixel FSTN positive gray LCD

Data Conversion AD Converter filter

Measurement Range Resolution Strain Range plusmn155mVV

Resolution plusmn00005mVV

Measurement Accuracy plusmn01 of reading plusmn3 counts

Gage Factor Control 0500-9900

Balance Control Software either manual or automatic

Bridge Excitation 15VDC nominal

Communication Interface USB Cable Included

Data Storage Removable Media Card

Shunt Calibration Across bridge completion resistors controlled

by software When Gage Factor=200

120Ω350Ω1000Ω

Analog Output Value 0 to 25V max

Ranges plusmn320 microε plusmn3200 microε plusmn32000 microε

Error 05 output voltage +5mV

Max Error 14 output voltage + 20mV

Update rate 480 samplessec

Output Load 2000Ω

Power Battery Two Alkaline D cells

Battery life 400 hours typ

USB 5V 100mA

Operational Environment Temperature 0-50

Humidity Up to 90 Non-condensing

Case Aluminum Alloy

Size and Weight 228times152times152(mm) 20(kg)

Table 3-2 Vishay Micro-Measurements Model P3 Strain Indicator and Recorder Specs

45

323 Strain Gauge

The strain gaugersquos main basic principle is to use a resistancersquos characteristics to measure the strain

The inside connections of the strain indicator are shown in figure 3-5

Fig 3-5 Inner Connections

As shown above this is a quarter-bridge connection We connect equal-length 3 wires to the 2

connections allowed by the strain gauge wire 1 and 3 can be used to cancel out the effects of temperature

to the resistance and because of the addition of wires 1 and 3 wire 2 can directly measure the experiment

results from the strain gauge and therefore the strain developed with no influence of temperature

If there were no two measuring leads then the relations will be

R 4 =R g +2R L

Where Rg is the Strain Gauge Value and RL is the wire resistance then

4

4

R

R=

Lg

g

RR

R

2

=

gL

gg

RR

RR

21

amp

4

4

R

R=

g

g

R

R(1- L)

Where L is the Signal Loss Factor and so

L =gL

gL

RR

RR

21

2

g

L

R

2R if

g

L

R

2Rltlt1

46

(Actual Value R g =120R L =08g

L

R

2Ris always much smaller than 1)

R 4 =R g +2R LR 2 =R 3 =rR gR 1 =R g 32 RR =0

V 0 =V 2)1( r

r

(

4

4

R

R-

1

1

R

R)

The first term describes loss attenuation effects second term describes loss of balancing capabilities

effects

V 0 =V 2)1( r

r

[

)2

(Lg

g

RR

R

+

T

Lg

g

RR

R

)

2( + T

Lg

L

RR

R

)

2

2( -(

g

g

R

R) T ]

The first term describes loss attenuation effects and loss of balancing capabilities effects the second

third and fourth terms describe the temperature effects on the wire

For the three-wire method we have

L =gL

gL

RR

RR

1

g

L

R

R if

g

L

R

Rltlt1

V 0 =V 2)1( r

r

[

)(Lg

g

RR

R

+

T

Lg

g

RR

R

)( + T

Lg

L

RR

R

)

2( -

T

Lg

g

RR

R

)( - T

Lg

L

RR

R

)

2( ]

V 0 = V2)1( r

r

)(

Lg

g

RR

R

In the last four terms inside parenthesis we can see the effects of temperature being cancelled out and the

effect on first term is not great so this is the reason why in our research we use three wires

47

324 Specimen Measurements

The tensile specimens used in this research are compliant of ASTM E8 Tensile parameters as shown

in figure 3-6

Fig 3-6 Tensile Specimen

Diameter

D(mm)

Gauge

Length

G(mm)

Smallest

Arc

Radius

R(mm)

Shortest

Area

A(mm)

Total

Length

L(mm)

Clamping

Area

Length

B(mm)

Clamping

Area

Diameter

C(mm)

Bar 125 02 625 01 gt10 gt75 ~ 145 ~ 35 20

Table 3-3 Specifications for Round Bar

33 Experiment Procedure

1 Attaching the Strain Gauge to the Tensile Specimen

(1) Prepare 1 ASTM E8 compliant tensile specimen round bar as shown in figure 3-7

(2) Prepare Strain Gauge as those described in table 3-4

(3) Prepare other consumables and adhesive agent such as epoxy adhesive or

cyanoacrylate adhesive as shown in figure 3-8

48

Fig 3-7 Actual Tensile Specimen

Fig 3-8 Other Materials Used (Such as Alcohol gauze transparent tape adhesive)

Gage Type

EA-06-120LZ-120E

Resistance in ohms at 24∘C

1200plusmn03

Gage Factor at 24∘C

2075plusmn05

Transverse Sensitivity at 24∘C

(+07plusmn02)

Table 3-4 Specifications for Strain Gauge

2 Attaching Strain Gauge

As shown in following figures we shall explain the attachment of the strain gauge

(1) Use sand paper and a rasp to clean thoroughly the surface where the strain gauge will be

attached to

49

(a)

(2) Use alcohol to wash the surface where the strain gauge will be attached and use gauze to rub

it off

(b)

(3) Find a clean surface and clean it with alcohol and gauze

(c)

(4) Place the strain gauge in the clean surface Use a piece of transparent tape on top of the strain

gauge after securely placed rip it off the surface carefully

50

(d)

(5) Use a piece of white paper to mark the place where the strain gauge will be attached and in

this way we can make sure that the strain gauge will be placed as horizontally and vertically

correct as possible

(e)

(6) In the place where we had our mark place the strain gauge

(f)

(7) Carefully lift one side of the tape and apply some of the adhesive agent to both the strain

gauge and specimenrsquos surface

(g)

51

(8) We need to make sure that the gauge and the specimen will be firmly attached so we gently

apply pressure with our thumb

(h)

(9) After the adhesive is fully dry we can carefully rip off the tape

(i)

(10) We need to do the whole process twice one for the horizontally placed strain gauge and one

for the vertically placed strain gauge

52

(j)

(11) We now proceed to solder the wires to the strain gauge

(k)

(12) After soldering we use a Volt Multimeter to measure that there is no contact between wires

If there is none then the specimen is ready for testing

(l)

(13) We now need to measure a 5cm distance and mark it to check and compare the elongation

before and after the tensile testing

(m)

53

Fig 3-9 Specimen-Strain Gauge Process

3 Tensile Test

(1) Enter the computer application that controls the tensile testing machine

(2) Turn on the tensile testing machine main switch

(3) Adjust the hydraulic pump to go back to its original position

(4) Bring the lowering motor down to a distance enough so as to attach the tensile specimen to the

system open the clamps and secure the specimen

(a)

(5) Connect all the necessary wires to the strain indicator equipment

54

(b)

(6) Start the ascending motor and wait for the expansion

(c)

Fig 3-10 Specimen-Tensile Testing Process

4 Start the Test

(1) Enter the software application and enter some variables needed for the experiment in the

specific screen

(2) Go back to the main screen and press the [測試] (measure) button to start the test and auto

recording in the software

(3) After the specimen breaks the mechanical device will automatically stop and ask the user to

enter the total displacement We take out the specimen from the testing machine and adjust the

machinersquos position back to its original position

(4) Save the results information

(5) Record the results from the strain indicator

34 Results

From this experiment we can get the Poissonrsquos Ratio Youngrsquos Modulus and Yield Strength etc and

because of the slippage phenomenon in the clamp at the moment of the test then the Elastic Limit will

display some yield phenomena So omit any undesirable results we just take the Yield portion of the

results as reference

In the process of the experiment the most important part to attend to is the attaching of the strain

gauge because the gaugersquos purpose is to measure the strain developed during the test and this strain

might be very small If the gaugersquos angle change during the test ie is not well attached this will affect

the accuracy of the measurements of Poissonrsquos ratio and Youngrsquos modulus

55

The materials provided by the manufacturer are SUM 23 and SUM 43 steel round bars and these two

types of materials have been through different heat treatment processes so they can be sub-divided

further into untreated material heat-treated material and black surface heat treated material for the two

materials with heat treatment the treatment process and finished are different In the end we only have

the mechanical properties that were calculated after our research of these materials

All of the specifications are identical to those shown in figure 3-6

341 SUM 23

Fig 3-11 SUM 23 Untreated Material

Number 7 10

Hardness(HRB) 74 75

Yield Stress (MPa) 448 440

Tensile Strength (MPa) 544 560

Poissonrsquos Ratio 029 027

Youngrsquos Modulus (GPa) 203 210

Cut-off Area Shrinking () 42 41

Elongation () 1125 1011

Table 3-5 Mechanical Properties of SUM 23 Untreated

56

Stress-Strain Diagram

(a)

(b)

57

Fig 3-12 Stress-Strain Diagrams for (a) 7 Round Bar and (b) 10 Round Bar

Cut-Off Area

(a)

(b)

Fig 3-13 Cut-Off Area of (a) 7 Round Bar and (b) 10 Round Bar

58

SUM 23 Nickel Round Bar

Fig 3-14 SUM 23 Nickel Material

Number 1 2 3 4

Hardness(HRB) 48 50 49 48

Yield Stress (MPa) 370 370 380 400

Tensile Strength (MPa) 455 451 450 450

Poissonrsquos Ratio 028 046 029 026

Youngrsquos Modulus (GPa) 243 303 246 206

Cut-off Area Shrinking () 803 803 726 601

Elongation () 566 65 602 647

Table 3-6 Mechanical Properties of SUM 23 Nickel

59

Stress-Strain Diagram

(a)

60

(b)

(c)

(d)

61

Fig 3-15 Stress-Strain Diagrams for (a) 1 Round Bar (b) 2 Round Bar (c) 3 Round Bar and (d)

4 Round Bar

Cut-Off Area

(a)

(b)

62

(c)

(d)

Fig 3-16 Cut-Off Area of (a) 1 Round Bar (b) 2 Round Bar (c) 3 Round Bar and (d) 4 Round

Bar

63

SUM 23 Black Surface Round Bar

Fig 3-17 SUM 23 Black Surface Material

Number 1 2 3

Hardness(HRB) 51 50 51

Yield Stress (MPa) 378 371 369

Tensile Strength (MPa) 467 465 464

Poissonrsquos Ratio 03 016 04

Youngrsquos Modulus (GPa) 215 266 266

Cut-off Area Shrinking () 986 94 848

Elongation () 748 805 761

Table 3-7 Mechanical Properties of SUM 23 Black Surface Material

64

Stress-Strain Diagram

(a)

(b)

65

(c)

Fig 3-18 Stress-Strain Diagrams for (a) 1 Round Bar 2 Round Bar and (c) 3 Round Bar

Cut-Off Surface

(a)

66

(b)

(c)

Fig 3-19 Cut-Off Surface of (a) 1 Round Bar 2 Round Bar and (c) 3 Round Bar

67

342 SUM 43

Fig 3-20 Untreated SUM 43 Untreated Material

Number 1 5

Hardness(HRB) 76 75

Yield Stress (MPa) 572 594

Tensile Strength (MPa) 743 785

Poissonrsquos Ratio 027 029

Youngrsquos Modulus (GPa) 200 202

Cut-off Area Shrinking () 338 2944

Elongation () 857 894

Table 3-8 Mechanical Properties of SUM 43 Untreated

68

Stress-Strain Diagrams

(a)

(b)

Fig 3-21 Stress-Strain Diagrams for SUM 43 (a) 1 Round Bar and (b) 5 Round Bar

69

Cut-Off Area

(a)

(b)

Fig 3-22 Cut-Off Area of SUM 43 (a) 1 Round Bar and (b) 5 Round Bar

70

SUM 43 Nickel Round Bar

Fig 3-23 SUM 43 Nickel Material

Number 4 5

Hardness(HRB) 51 50

Yield Stress (MPa) 1580 1544

Tensile Strength (MPa) 1639 1625

Poissonrsquos Ratio 03 028

Youngrsquos Modulus (GPa) 194 201

Cut-off Area Shrinking () 1697 137

Elongation () 376 265

Table 3-9 Mechanical Properties of SUM 43 Nickel

71

Stress-Strain Diagrams

(a)

(b)

Fig 3-24 Stress-Strain Diagrams for (a) 4 Round Bar and (b) 5 Round Bar

72

Cut-Off Area

(a)

(b)

Fig 3-25 Cut-Off Area of (a) 4 Round Bar and (b) 5 Round Bar

73

SUM 43 Black Surface Material

Fig 3-26 SUM 43 Black Surface Material

Number 3 5

Hardness(HRB) 56 56

Yield Stress (MPa) 1416 1361

Tensile Strength (MPa) 1591 1402

Poissonrsquos Ratio 029 031

Youngrsquos Modulus (GPa) 200 202

Cut-off Area Shrinking () 139 124

Elongation () 24 24

Table 3-10 Mechanical Properties of SUM 43 Black Surface Material

74

Stress-Strain Diagrams

0 2 4 6 8 10 12 14

-200

0

200

400

600

800

1000

1200

1400

1600

1800

應力 (MPa)

應變()

(a)

0 2 4 6 8 10

-200

0

200

400

600

800

1000

1200

1400

1600

應力

(MPa)

位移 ()

(b)

Fig 3-27 Stress-Strain Diagrams for (a) 3 Round Bar and (b) 5 Round Bar

(Note These curves were formulated using Visual Solutions Inc VisSim Software)

75

Cut-Off Area

(a)

(b)

Fig 3-28 Cut-Off Area of (a) 3 Round Bar and (b) 5 Round Bar

76

The force value (N) was retrieved from the Universal Testing Machine

The Poissonrsquos Ratio (ε) is calculated as

ε =

the values for the Poissonrsquos Ratio are in average around 0297

The Youngrsquos Modulus (E) is calculated as

E =

Where

Stress =

Cross-sectional Area =

where D is the Diameter

The value for D was in average around 1258 mm

The values shown by the computer because there is Slippage phenomena between the Clamp and the

specimen will not be taken into consideration for the elongation strain and Youngrsquos modulus and we will

refer to the values that we have meticulously calculated

77

Chapter 4 AR COATING IN DEPTH

41 Experimentrsquos Purpose and Principles

By means of a vacuum chamber and several other instruments we intend to apply Anti-Reflective

Coating using deposition process to a laser diode and in this way reduce its refraction so as to make it

lose less light in the process of amplification and we can control certain wavelengths we want produced

for certain desired applications in our case we are attempting to re-create a Bose-Einstein Condensate

An optimal BEC apparatus is shown in figure 4-1

Fig 4-1 BEC Apparatus

The main point of this experiment is to build a vacuum chamber system attach all the instrumentation

needed (Vacuum pump deposition meter and voltmeter) and use it to apply AR coating to a laser diode

After we have accomplished the AR coating other team will be in charge of designing the BEC apparatus

and use the results of our research

78

42 Experimentrsquos Equipment

421 Vacuum Chamber

For this research we designed a vacuum chamber whose main body is shown in figure 4-2 Its

dimensions are

Width 240 mm

Length 240 mm

Height 200 mm

Outer Diameter 4 in

Inner Diameter 15 in

Fig 4-2 Vacuum Chamber Main Body

The chamber is made up of 6 pass ways pass way A is the connection with the Laser Deposition

Equipment pass way B is the connection with the Turbo Pump and pass way C is for the connection with

the Deposition Source

A

C

B

79

Pass way C is for the deposition source as mentioned above This is a system where a thermal

resistance is heated by passing a high current through it which heats up a filament boat (made of tungsten)

where the material to be evaporated is place We control the temperature as such that the material will

evaporate and the heat will not cause the filament boat to crack

Because P = Isup2 R (where P is power I is current and R is resistance) to avoid the current to flow

where it is not desired we decided that the material for the Thermocouple shown in figure 4-3 should be

Copper ᴓ 63 mm We choose it that way because Copper has very good heat dissipation characteristics

and the resistance value is low It can reduce the value of the current enough to make the thermocouple to

create heat

Fig 4-3 Thermocouple

To the thermocouple we attach the tungsten filament boat We need to take notice of materials to be

used in this design because when using high current the tungsten filament boar will heat up and so the

material must be able to keep up with the heating potential of tungsten and has a low coefficient of heat

dissipation to avoid the tungsten to fail when heating up and therefore not evaporating Considering all

this we decide to use Stainless Steel

Because this clamp will be assembled inside the chamber after many revisions it was determined it

will have the shape shown in figure 4-4

Fig 4-4 Filament Boat Clamp Design

80

For the tungsten filament boat we bought the product from a distributor The dimensions are

Length 100 mm

Width 10 mm

Height 1 mm

Our thermocouple is 15 in but the pass way C is 4 in so we need to attach a Flange that connects

15in to 4in Because these specifications are quite difficult to achieve by Milling we had to use

electrical wire cutting

For the laser clamping system where the laser that is going to be AR coated will be placed will be

connected to pass way A the assembly is shown in figure 4-5 below

Fig 4-5 Cover Assembly

For this design we used an O-ring instead of a gasket so as to save time The design of the assembly

where the laser will be placed is shown in figure 4-6

Fig 4-6 Upper Cover Inner Assembly

D

E

F

81

Point D is the plate in the assembly where the laser diode will be fixed Because of the easy

processing we decide to use Aluminum and it is screwed to the top cover Point E is the connection for

the Quartz crystal resonator and it is designed in the same as point F in this way the results of the quartz

microbalance system will be more accurate in real time Point F is the final resting place for the laser

diode We use a Thor Labs Base with dimensions of ᴓ 9mm and ᴓ 56mm for two different size laser

diodes It just needs to be plugged in for easy installation

From figure 4-6 we know that the system needs signal system connections and because of the

change in temperature inside the chamber this could affect the functioning of the quartz microbalance so

we also need to install water tubes for cooling This is shown in figure 4-7 below

Fig 4-7 Diagram of Upper Cover Connections

In figure 4-8 we show the Feed through connections and their functions

Fig 4-8 Feed through Diagram

82

1 SQM-160 wire 5 Laser Connection 1 (Vin)

2 SQM-160 (G) 6 Laser Connection 2 (G)

3 K-Type-1 7 Laser Connection 3 (PD)

4 K-Type-2 8 Not In Use

The fully assembled chamber is shown in figure 4-9

Fig 4-9 Fully Assembled Chamber

422 Quartz Crystal Microbalance

For measuring the deposition on our target for coating we used the Inficon SQM-160 RateThickness

Monitor It is an easy to use instrument for measuring many types of thin-film coatings as shown in

figure 4-10

(a) Front Panel (b) Back Panel

Fig 4-10 Inficon SQM-160

83

Table 4-1 shows the technical specifications for this equipment

Number of sensors 2 Standard 4 additional optional

Sensor Frequency Range 40 MHz ~ 60 MHz

Reference Frequency Accuracy 002

Thickness Display Resolution 1 Aring

Thickness Resolution 015 Aring (Std) 0037 Aring (Hi Res)

Density of Stored Films 05-9999 gmcc

Tooling 10-399

Z-Factor 010-1000

Final Thickness 0000-9999k Aring

Measurement Period 15 to 2 sec

Simulation Mode Yes

Frequency Mode Yes

Rate Resolution 011 Arings

Dual Crystal Yes

Etch Mode Yes

Crystal Tooling 10-399

Crystal Fail Min Max 40 to 60 MHz 41 to 61 MHz

Power 100-120 200-240~plusmn10 nominal 20W

Operation Environment 0degC ~ 50degC

0 ~ 80 RH non-condensing

0 ~ 2000 meters

Class 1 Equipment

Pollution Degree 2

Rack Dimensions 885mm x 2127mm x 1969mm

Weight 27 kg

Table 4-1 Inficon SQM-160 RateThickness Monitor Specs

84

To the SQM-160 we need to connect an Oscillator We use the Sigma Instruments Remote Oscillator

Ser No 2 268 as shown in figure 4-11

Fig 4-11 Sigma Instruments Remote Oscillator

The connections diagram is shown in figure 4-12

Fig 4-12 SQM-160 Connections Diagram

85

423 Turbo Pump

For our experiments we used the Pfeiffer TCP 015 Electronic Drive Unit shown below in figure 4-13

Table 4-2 shows the technical specifications for this equipment

(a) Front Panel (b) Back Panel

Fig 4-13 Pfeiffer TCP 015 Electronic Drive

Connection Voltage (100V) 90-112

Mains Frequency 5060 Hz

Start-up Current 22 A

Nominal Frequency 1500 Hz

Rotation Speed 10V = 1500Hz plusmn2

Analog Output Current 10 V = 25 A plusmn 5

Rotation Speed Switchpoint 750 Hz

Works Setting 8 min

Permissible Ambient Temperature 0degC ~ 40degC

Dimensions Front Panel 1285mm x 1063mm

Insertion Length 227mm

Weight 27 Kg

Table 4-2 Pfeiffer TCP 015 Electronic Drive Specs

86

The connections diagram is shown in figure 4-14

Fig 4-14Connections Diagram for Pfeiffer TCP 015

To measure the pressure inside the chamber we use the Granville Phillips 375 Convectron Vacuum

Pressure Controller shown in figure 4-15

(a) Front Panel (b) Back Panel

Fig 4-15 Granville Phillips 375 Convectron

87

Its dimensions are shown in figure 4-16

Fig 4-16 Dimensions of Convectron

Table 4-3 shows the technical specifications for this equipment

Table 4-3 Granville Phillips 375 Convectron Vacuum Pressure Controller Specs

88

424 Multimeter

For our experiment we used the Keithley 2000 Digital Multimeter as shown in figure 4-17

(a) Front Panel (b) Back Panel

Fig 4-17 Keithley Model 2000 6-12-Digit Digital Multimeter

Its technical specifications are shown in table 4-4

Table 4-4 Keithley Model 2000 6-12-Digit Digital Multimeter Specs

89

43 Experiment Procedure

1 Connecting together the equipment and the chamber

(1) We first connect the resonator to the thickness monitor and connect the other side to the

chamber

(2) We now connect the flexible tubes to the turbo pump on one side and to the chamber on the

other

(3) We need to check that tubes are tightly connected to avoid any leaks in the vacuum pumping

process which will not allow us to get to our goal of Torr As shown in figure 4-18

(4) Connect the convectron to the system as shown in figure 4-19

Fig 4-18 checking for leaks using alcohol

Fig 4-19 Convectron attached to System

90

(5) Attach the clamps of the Multimeter to the bottom of the chamber as shown in figure 4-20

(6) Place the Quartz crystal in place

(7) Close tight vacuum chamber

(8) Connect all electrical appliances to power source

Fig 4-20 Multimeter Connections

2 Starting up the System

(1) We turn on all the devices as such Check all systems are ready to function Reset all values

that might be left over from previous tests

(2) Start the thickness monitor and set all values for this experiment In our case we got to testing

the system but not actual coating So we used the simulation mode of the thickness monitor as

shown in figure 4-21

Fig 4-21 Simulation Mode

91

(3) Start the turbo pump Make sure the lid on the vacuum chamber is tightly closed

(4) Start convectron and record initial pressure

(5) Start Multimeter and record initial current

3 Coating Process

(1) If we have the deposition material inside the filament boat the power source for the high

current must be started as well

(2) Record all initial values for thickness current pressure

(3) For an ideal experiment we need a thickness of around 101 nm a pressure of Torr and

a current of 300 A

44 Results

From previous experiments we have shown that we can turn a LED into a laser by means of AR

Coating In figure 4-22 shown below we can compare the actual results of a Diode before and after AR

coating From the blue line we can see that when the diode is at a current of 15mA its light will change

from LED to laser and if we look at the red line its critical current is around 30 to 35 mA

Fig 4-22 AR Coating Comparison for Laser Diodes

This means that the light emitted is not as strong as if the diode had been coated because inside the

chamber there must be some excitation first so the reflectivity of both sides inside the diode must be high

So because of the coating in one of the sides we have opened a door and let the light come out so the

critical current is risen as such and will be higher value than that of before the coating

92

In the following figures we can see the difference between before and after coating in a material The

thickness is around 1016 nm for this material

Fig 4-23 Before Coating

Fig 4-24 After Coating

93

Chapter 5 CONCLUSIONS AND RECOMMENDATIONS

51 Conclusions

For the first part of this independent study taking into consideration the data that came out of our

research and that sent by the provider we can say

1 SUM 23 after heat treatment will unexpectedly develop cracking in the middle of the tensile

testing process and suddenly break

2 Itrsquos possible that in the process of heat treatment to the SUM 23 material the treatment was not

uniform and this will create a pre-loaded moment force on one side that pushes on the other side

of the specimen resulting in material deformation

3 In the process of attaching the strain gauges to the materials it is very easy to make errors due to

poor adhesion or sudden removal in the tensile testing process

For our second part of the independent study the following can be made

1 At the beginning of this independent study we had no idea what Bose-Einstein Condensate was

or what was its purpose After much literature we finally comprehended the basic principles to

put into practice for our research

2 Our systemrsquos basic working principles and equipmentrsquos complexity are a little difficult to grasp

but hopefully we were able to understand enough of it

3 Theoretically from relation between the power and current we can know the advantages and

disadvantages of AR Coating

4 We were able to assemble the system and run test on its functions Even though we were able to

do this there is still much more work left to do with this system

52 Recommendations

For the Tensile Testing the following can be said

1 Ask the provider to check on the process of heat treatment on the SUM 23 material and give

them the information we have gathered through our test so they can correct for the mechanical

properties found if any change is needed

2 To avoid the problem of the inaccuracy of the poor adhesion of strain gauges we can attach

multiple strain gauges to the same one specimen so as to correlate data and improve our results

For the AR Coating the following can be said

1 We need to make sure that there are no physical defects on the main body of the chamber so as to

achieve maximum efficiency in the vacuum process If there was then the vacuum will arrive to

certain point and then start to decrease

2 It would be preferable to add some sort of visual aid that will allow the user to check the inside of

the chamber without actually opening it This will help us determine at what times we should

manipulate the current to better evaporate the substrate

94

REFERENCES

[1] A L Window Strain Gauge Technology Elsevier Applied Science London and New York 2nd

Edition 1992

[2] CC Perry and HR Lissner Strain Gauge Primer McGraw-Hill Book Co Inc New York 1955

[3] James W Dally William F Riley McGraw-Hill 1978

[4] University of Colorado Boulder BEC - What is it and where did the idea come from

httpwwwcoloradoeduphysics2000becwhat_is_ithtml

[5] Ultraslow Light amp Bose-Einstein Condensates Two-way Control with Coherent Light amp Atom

Fields Harvard Hau Lab Dr Lene Vestergaard Hau Optics amp Photonics News 16 1995

[6] The Art of Taming Light Ultra-slow and Stopped Light Harvard Hau Lab Dr Lene

Vestergaard Hau Europhysics News 2004

[7] Nonlinear Optics Shocking Superfluids Harvard Hau Lab Dr Lene Vestergaard Hau Nature

Physics 2007

[8] Model P3 Strain Indicator and Recorder Instruction Manual Vishay Micro-Measurements 2005

[9] Granville-Phillips Series 375 Convectron Vacuum Gauge Controller Instruction Manual Brooks

Automation 2008

[10] Effect of Film Thickness on the Validity of the Sauerbrey Equation for Hydrated Polyelectrolyte

Films Vogt Lin Wu White 2004

[11] Quartz Crystal Microbalance Study of DNA Immobilization and Hybridization for DNA Sensor

Development Chang Zhao 2008

[12] Installation of Strain Gages with SR-4 PrecoatAdhesive Vishay Micro-Measurements 2005

[13] Strain Gauge Measurement ndash A Tutorial National Instruments 1998

[14] Correlation between Vickers Hardness Number and Yield Stress of Cold-Formed Products

Yavuz Tekkaya

[15] httpsenwikipediaorg

Page 38: PC Hinge Materials Testing and AR Laser Diode Coating

38

Table 2-2 Continued

235 Vacuum Chamber System

Vacuum Evaporation is the process of depositing thin films of materials onto surfaces The technique

consists of pumping a vacuum chamber to pressures of less than torr and heating a material to

produce a flux of vapor in order to deposit the material onto a surface The material to be vaporized is

typically heated until its vapor pressure is high enough to produce a flux several Angstrom per second by

using an electrically resistive heater or bombardment by a high voltage beam The process was invented

by Henri Nestle in 1886 for food industry

In here the system has been pumped to a vacuum of Torr When a high current is passed

through the filament boat the filament boat is heated over the desired metal evaporation temperature and

so evaporation starts When the evaporation process is finished and the metal cools down crystals

condensate in the surface of the wafer From the weight of the evaporated material the distance between

the filament boat and the wafer we are able to calculate the deposition thickness and we can also use the

mass detector follower like the Quartz crystal resonator microbalance system In the process of

evaporation we usually use a board in between the filament boat and the wafer This is because before we

arrive to the desired evaporation temperature there will be some impurities that will be vaporized in the

controlled environment so we first use a small current and the board in between to get rid of those

impurities and this raises the purity of the deposition material

39

A vacuum evaporation system is shown in figure 2-24

Fig 2-24 Vacuum Evaporation System

Rough Vacuum 760 ~ 1 torr

Medium Vacuum 1 ~ torr

High Vacuum ~ torr

Ultra-High Vacuum Lower than torr

Table 2-3 Classification of Vacuum

For our study we need to use a Turbo Pump A regular turbo pump is shown in figure 2-25

Fig 2-25 Turbo Pump

For our research we used the Pfeiffer TCP 015 Electronic Drive Unit and Granville Phillips 375

Convectron shown below in figure 2-26

40

Fig 2-26 Control and Measurement Equipment

The electronic drive controls the turbo pump and the Convectron measures the pressure inside our

chamber The turbo pump is a type of vacuum pump used to maintain high vacuum Most turbo pumps

are centrifugal When we start the pumping we need to use a mechanical pump so as to decrease the

pressure inside the system from constant atmospheric pressure to torr and then the use dispersion

pump to continue the vacuum until we get to the desired pressure We need to notice though when we

start the dispersion pump we canrsquot turn off the mechanical pump and they both need to run together If

we need to turn off the pumping we first turn off the dispersion pump wait for it to completely stop and

then turn off the mechanical pump

Our completely assembled system is shown in figure 2-27 below

Fig 2-27 Complete System

41

Chapter 3 TENSILE TESTING IN DEPTH

31 Experimentrsquos Purpose and Principles

By means of Universal testing machine and Strain gauges we were able to observe discuss and

analyze the phenomena created when a specimen of certain material is manipulated under an external load

and determine the stress strain and deformation values later we can use the graphing methods of

stress-strain diagram to describe it

The main point of this experiment is that after the tensile specimen is tested use computer analysis

and the actual strain data and after statistical adjustment make the final results report (Tensile testing

experiment is in accordance with ASTM E8)

32 Experimentrsquos Equipment

321 Universal Testing Machine

For the materials testing experiment part of this research we use a Universal Testing Machine as

shown in figure 31 The maximum load it can apply is 100 Ton After the test specimen is secured on the

device with the use of instrumentation the load exerted and the effects of this become apparent on the

specimen and even the smallest of changes can be recorded For our research we used the Chun Yen

Testing Machines Co Ltd 100 Ton Micro Computer Universal Tensile Tester

Fig 31 Universal Testing Machine

42

Table 31 shows the specifications for this machine

Max Capacity 100 Ton

Accuracy plusmn1

Tension (mm) Max Space 1150mm

Grip for Rod 20-70mm

Ram Stroke 250mm

Effective Column Interval 940mm

Crosshead Speed 300mmmin

Testing Speed 0-50mmmin

Volume of Machine 1700times1000times3350mm(LtimesWtimesH)

Volume of Control Panel 1000times800times1500mm(LtimesWtimesH)

Weight 8000kg

Power 3∮220V 20A

Computer AMD K6-2-350

OS Windows XP

Screen 15rdquo CRT

Table 3-1 Chun Yen Testing Machine Specs Table

The connections diagram is shown in figure 3-2

Fig 3-2 Diagram for System Connections

43

When the test specimen is placed when the external force is applied the Load Cell can measure the

size of the applied force and the Encoder measures the expansion rate of change The Local Controller

receives all the information from the 2 units after arranging the results they are displayed in the

computer and they can be afterwards submitted for more complex analysis such as Finite Element

Analysis and we can get the Stress-Strain Diagram

322 Strain Measurement Equipment

The equipment used in our research provides a four-channel measurement that means we can use up

to 4 strain gauges at a time to do our measurements and provides 3 different bridge arrangements as

shown in figure 3-3

(a) (b) (c)

Fig 3-3 Input Connections for Strain Indicator

Figure 3-3 (a) is the Quarter Bridge (b) is the Half Bridge and (c) is the Full Bridge and Transducers

For our study we used the Quarter Bridge and use the Strain Gauge values to decide the position of the

connecting wires The Strain indicator is shown in figure 3-4

Fig 3-4 Vishay Micro-Measurements Model P3 Strain Indicator and Recorder

44

Input Connections Tool Free eccentric lever release

4-channel input

Wire diameter16-28AWG

Bridge Configurations Quarter- Half- and Full Bridge

Bridge Impedance 60-2000Ω

Display 128 64 pixel FSTN positive gray LCD

Data Conversion AD Converter filter

Measurement Range Resolution Strain Range plusmn155mVV

Resolution plusmn00005mVV

Measurement Accuracy plusmn01 of reading plusmn3 counts

Gage Factor Control 0500-9900

Balance Control Software either manual or automatic

Bridge Excitation 15VDC nominal

Communication Interface USB Cable Included

Data Storage Removable Media Card

Shunt Calibration Across bridge completion resistors controlled

by software When Gage Factor=200

120Ω350Ω1000Ω

Analog Output Value 0 to 25V max

Ranges plusmn320 microε plusmn3200 microε plusmn32000 microε

Error 05 output voltage +5mV

Max Error 14 output voltage + 20mV

Update rate 480 samplessec

Output Load 2000Ω

Power Battery Two Alkaline D cells

Battery life 400 hours typ

USB 5V 100mA

Operational Environment Temperature 0-50

Humidity Up to 90 Non-condensing

Case Aluminum Alloy

Size and Weight 228times152times152(mm) 20(kg)

Table 3-2 Vishay Micro-Measurements Model P3 Strain Indicator and Recorder Specs

45

323 Strain Gauge

The strain gaugersquos main basic principle is to use a resistancersquos characteristics to measure the strain

The inside connections of the strain indicator are shown in figure 3-5

Fig 3-5 Inner Connections

As shown above this is a quarter-bridge connection We connect equal-length 3 wires to the 2

connections allowed by the strain gauge wire 1 and 3 can be used to cancel out the effects of temperature

to the resistance and because of the addition of wires 1 and 3 wire 2 can directly measure the experiment

results from the strain gauge and therefore the strain developed with no influence of temperature

If there were no two measuring leads then the relations will be

R 4 =R g +2R L

Where Rg is the Strain Gauge Value and RL is the wire resistance then

4

4

R

R=

Lg

g

RR

R

2

=

gL

gg

RR

RR

21

amp

4

4

R

R=

g

g

R

R(1- L)

Where L is the Signal Loss Factor and so

L =gL

gL

RR

RR

21

2

g

L

R

2R if

g

L

R

2Rltlt1

46

(Actual Value R g =120R L =08g

L

R

2Ris always much smaller than 1)

R 4 =R g +2R LR 2 =R 3 =rR gR 1 =R g 32 RR =0

V 0 =V 2)1( r

r

(

4

4

R

R-

1

1

R

R)

The first term describes loss attenuation effects second term describes loss of balancing capabilities

effects

V 0 =V 2)1( r

r

[

)2

(Lg

g

RR

R

+

T

Lg

g

RR

R

)

2( + T

Lg

L

RR

R

)

2

2( -(

g

g

R

R) T ]

The first term describes loss attenuation effects and loss of balancing capabilities effects the second

third and fourth terms describe the temperature effects on the wire

For the three-wire method we have

L =gL

gL

RR

RR

1

g

L

R

R if

g

L

R

Rltlt1

V 0 =V 2)1( r

r

[

)(Lg

g

RR

R

+

T

Lg

g

RR

R

)( + T

Lg

L

RR

R

)

2( -

T

Lg

g

RR

R

)( - T

Lg

L

RR

R

)

2( ]

V 0 = V2)1( r

r

)(

Lg

g

RR

R

In the last four terms inside parenthesis we can see the effects of temperature being cancelled out and the

effect on first term is not great so this is the reason why in our research we use three wires

47

324 Specimen Measurements

The tensile specimens used in this research are compliant of ASTM E8 Tensile parameters as shown

in figure 3-6

Fig 3-6 Tensile Specimen

Diameter

D(mm)

Gauge

Length

G(mm)

Smallest

Arc

Radius

R(mm)

Shortest

Area

A(mm)

Total

Length

L(mm)

Clamping

Area

Length

B(mm)

Clamping

Area

Diameter

C(mm)

Bar 125 02 625 01 gt10 gt75 ~ 145 ~ 35 20

Table 3-3 Specifications for Round Bar

33 Experiment Procedure

1 Attaching the Strain Gauge to the Tensile Specimen

(1) Prepare 1 ASTM E8 compliant tensile specimen round bar as shown in figure 3-7

(2) Prepare Strain Gauge as those described in table 3-4

(3) Prepare other consumables and adhesive agent such as epoxy adhesive or

cyanoacrylate adhesive as shown in figure 3-8

48

Fig 3-7 Actual Tensile Specimen

Fig 3-8 Other Materials Used (Such as Alcohol gauze transparent tape adhesive)

Gage Type

EA-06-120LZ-120E

Resistance in ohms at 24∘C

1200plusmn03

Gage Factor at 24∘C

2075plusmn05

Transverse Sensitivity at 24∘C

(+07plusmn02)

Table 3-4 Specifications for Strain Gauge

2 Attaching Strain Gauge

As shown in following figures we shall explain the attachment of the strain gauge

(1) Use sand paper and a rasp to clean thoroughly the surface where the strain gauge will be

attached to

49

(a)

(2) Use alcohol to wash the surface where the strain gauge will be attached and use gauze to rub

it off

(b)

(3) Find a clean surface and clean it with alcohol and gauze

(c)

(4) Place the strain gauge in the clean surface Use a piece of transparent tape on top of the strain

gauge after securely placed rip it off the surface carefully

50

(d)

(5) Use a piece of white paper to mark the place where the strain gauge will be attached and in

this way we can make sure that the strain gauge will be placed as horizontally and vertically

correct as possible

(e)

(6) In the place where we had our mark place the strain gauge

(f)

(7) Carefully lift one side of the tape and apply some of the adhesive agent to both the strain

gauge and specimenrsquos surface

(g)

51

(8) We need to make sure that the gauge and the specimen will be firmly attached so we gently

apply pressure with our thumb

(h)

(9) After the adhesive is fully dry we can carefully rip off the tape

(i)

(10) We need to do the whole process twice one for the horizontally placed strain gauge and one

for the vertically placed strain gauge

52

(j)

(11) We now proceed to solder the wires to the strain gauge

(k)

(12) After soldering we use a Volt Multimeter to measure that there is no contact between wires

If there is none then the specimen is ready for testing

(l)

(13) We now need to measure a 5cm distance and mark it to check and compare the elongation

before and after the tensile testing

(m)

53

Fig 3-9 Specimen-Strain Gauge Process

3 Tensile Test

(1) Enter the computer application that controls the tensile testing machine

(2) Turn on the tensile testing machine main switch

(3) Adjust the hydraulic pump to go back to its original position

(4) Bring the lowering motor down to a distance enough so as to attach the tensile specimen to the

system open the clamps and secure the specimen

(a)

(5) Connect all the necessary wires to the strain indicator equipment

54

(b)

(6) Start the ascending motor and wait for the expansion

(c)

Fig 3-10 Specimen-Tensile Testing Process

4 Start the Test

(1) Enter the software application and enter some variables needed for the experiment in the

specific screen

(2) Go back to the main screen and press the [測試] (measure) button to start the test and auto

recording in the software

(3) After the specimen breaks the mechanical device will automatically stop and ask the user to

enter the total displacement We take out the specimen from the testing machine and adjust the

machinersquos position back to its original position

(4) Save the results information

(5) Record the results from the strain indicator

34 Results

From this experiment we can get the Poissonrsquos Ratio Youngrsquos Modulus and Yield Strength etc and

because of the slippage phenomenon in the clamp at the moment of the test then the Elastic Limit will

display some yield phenomena So omit any undesirable results we just take the Yield portion of the

results as reference

In the process of the experiment the most important part to attend to is the attaching of the strain

gauge because the gaugersquos purpose is to measure the strain developed during the test and this strain

might be very small If the gaugersquos angle change during the test ie is not well attached this will affect

the accuracy of the measurements of Poissonrsquos ratio and Youngrsquos modulus

55

The materials provided by the manufacturer are SUM 23 and SUM 43 steel round bars and these two

types of materials have been through different heat treatment processes so they can be sub-divided

further into untreated material heat-treated material and black surface heat treated material for the two

materials with heat treatment the treatment process and finished are different In the end we only have

the mechanical properties that were calculated after our research of these materials

All of the specifications are identical to those shown in figure 3-6

341 SUM 23

Fig 3-11 SUM 23 Untreated Material

Number 7 10

Hardness(HRB) 74 75

Yield Stress (MPa) 448 440

Tensile Strength (MPa) 544 560

Poissonrsquos Ratio 029 027

Youngrsquos Modulus (GPa) 203 210

Cut-off Area Shrinking () 42 41

Elongation () 1125 1011

Table 3-5 Mechanical Properties of SUM 23 Untreated

56

Stress-Strain Diagram

(a)

(b)

57

Fig 3-12 Stress-Strain Diagrams for (a) 7 Round Bar and (b) 10 Round Bar

Cut-Off Area

(a)

(b)

Fig 3-13 Cut-Off Area of (a) 7 Round Bar and (b) 10 Round Bar

58

SUM 23 Nickel Round Bar

Fig 3-14 SUM 23 Nickel Material

Number 1 2 3 4

Hardness(HRB) 48 50 49 48

Yield Stress (MPa) 370 370 380 400

Tensile Strength (MPa) 455 451 450 450

Poissonrsquos Ratio 028 046 029 026

Youngrsquos Modulus (GPa) 243 303 246 206

Cut-off Area Shrinking () 803 803 726 601

Elongation () 566 65 602 647

Table 3-6 Mechanical Properties of SUM 23 Nickel

59

Stress-Strain Diagram

(a)

60

(b)

(c)

(d)

61

Fig 3-15 Stress-Strain Diagrams for (a) 1 Round Bar (b) 2 Round Bar (c) 3 Round Bar and (d)

4 Round Bar

Cut-Off Area

(a)

(b)

62

(c)

(d)

Fig 3-16 Cut-Off Area of (a) 1 Round Bar (b) 2 Round Bar (c) 3 Round Bar and (d) 4 Round

Bar

63

SUM 23 Black Surface Round Bar

Fig 3-17 SUM 23 Black Surface Material

Number 1 2 3

Hardness(HRB) 51 50 51

Yield Stress (MPa) 378 371 369

Tensile Strength (MPa) 467 465 464

Poissonrsquos Ratio 03 016 04

Youngrsquos Modulus (GPa) 215 266 266

Cut-off Area Shrinking () 986 94 848

Elongation () 748 805 761

Table 3-7 Mechanical Properties of SUM 23 Black Surface Material

64

Stress-Strain Diagram

(a)

(b)

65

(c)

Fig 3-18 Stress-Strain Diagrams for (a) 1 Round Bar 2 Round Bar and (c) 3 Round Bar

Cut-Off Surface

(a)

66

(b)

(c)

Fig 3-19 Cut-Off Surface of (a) 1 Round Bar 2 Round Bar and (c) 3 Round Bar

67

342 SUM 43

Fig 3-20 Untreated SUM 43 Untreated Material

Number 1 5

Hardness(HRB) 76 75

Yield Stress (MPa) 572 594

Tensile Strength (MPa) 743 785

Poissonrsquos Ratio 027 029

Youngrsquos Modulus (GPa) 200 202

Cut-off Area Shrinking () 338 2944

Elongation () 857 894

Table 3-8 Mechanical Properties of SUM 43 Untreated

68

Stress-Strain Diagrams

(a)

(b)

Fig 3-21 Stress-Strain Diagrams for SUM 43 (a) 1 Round Bar and (b) 5 Round Bar

69

Cut-Off Area

(a)

(b)

Fig 3-22 Cut-Off Area of SUM 43 (a) 1 Round Bar and (b) 5 Round Bar

70

SUM 43 Nickel Round Bar

Fig 3-23 SUM 43 Nickel Material

Number 4 5

Hardness(HRB) 51 50

Yield Stress (MPa) 1580 1544

Tensile Strength (MPa) 1639 1625

Poissonrsquos Ratio 03 028

Youngrsquos Modulus (GPa) 194 201

Cut-off Area Shrinking () 1697 137

Elongation () 376 265

Table 3-9 Mechanical Properties of SUM 43 Nickel

71

Stress-Strain Diagrams

(a)

(b)

Fig 3-24 Stress-Strain Diagrams for (a) 4 Round Bar and (b) 5 Round Bar

72

Cut-Off Area

(a)

(b)

Fig 3-25 Cut-Off Area of (a) 4 Round Bar and (b) 5 Round Bar

73

SUM 43 Black Surface Material

Fig 3-26 SUM 43 Black Surface Material

Number 3 5

Hardness(HRB) 56 56

Yield Stress (MPa) 1416 1361

Tensile Strength (MPa) 1591 1402

Poissonrsquos Ratio 029 031

Youngrsquos Modulus (GPa) 200 202

Cut-off Area Shrinking () 139 124

Elongation () 24 24

Table 3-10 Mechanical Properties of SUM 43 Black Surface Material

74

Stress-Strain Diagrams

0 2 4 6 8 10 12 14

-200

0

200

400

600

800

1000

1200

1400

1600

1800

應力 (MPa)

應變()

(a)

0 2 4 6 8 10

-200

0

200

400

600

800

1000

1200

1400

1600

應力

(MPa)

位移 ()

(b)

Fig 3-27 Stress-Strain Diagrams for (a) 3 Round Bar and (b) 5 Round Bar

(Note These curves were formulated using Visual Solutions Inc VisSim Software)

75

Cut-Off Area

(a)

(b)

Fig 3-28 Cut-Off Area of (a) 3 Round Bar and (b) 5 Round Bar

76

The force value (N) was retrieved from the Universal Testing Machine

The Poissonrsquos Ratio (ε) is calculated as

ε =

the values for the Poissonrsquos Ratio are in average around 0297

The Youngrsquos Modulus (E) is calculated as

E =

Where

Stress =

Cross-sectional Area =

where D is the Diameter

The value for D was in average around 1258 mm

The values shown by the computer because there is Slippage phenomena between the Clamp and the

specimen will not be taken into consideration for the elongation strain and Youngrsquos modulus and we will

refer to the values that we have meticulously calculated

77

Chapter 4 AR COATING IN DEPTH

41 Experimentrsquos Purpose and Principles

By means of a vacuum chamber and several other instruments we intend to apply Anti-Reflective

Coating using deposition process to a laser diode and in this way reduce its refraction so as to make it

lose less light in the process of amplification and we can control certain wavelengths we want produced

for certain desired applications in our case we are attempting to re-create a Bose-Einstein Condensate

An optimal BEC apparatus is shown in figure 4-1

Fig 4-1 BEC Apparatus

The main point of this experiment is to build a vacuum chamber system attach all the instrumentation

needed (Vacuum pump deposition meter and voltmeter) and use it to apply AR coating to a laser diode

After we have accomplished the AR coating other team will be in charge of designing the BEC apparatus

and use the results of our research

78

42 Experimentrsquos Equipment

421 Vacuum Chamber

For this research we designed a vacuum chamber whose main body is shown in figure 4-2 Its

dimensions are

Width 240 mm

Length 240 mm

Height 200 mm

Outer Diameter 4 in

Inner Diameter 15 in

Fig 4-2 Vacuum Chamber Main Body

The chamber is made up of 6 pass ways pass way A is the connection with the Laser Deposition

Equipment pass way B is the connection with the Turbo Pump and pass way C is for the connection with

the Deposition Source

A

C

B

79

Pass way C is for the deposition source as mentioned above This is a system where a thermal

resistance is heated by passing a high current through it which heats up a filament boat (made of tungsten)

where the material to be evaporated is place We control the temperature as such that the material will

evaporate and the heat will not cause the filament boat to crack

Because P = Isup2 R (where P is power I is current and R is resistance) to avoid the current to flow

where it is not desired we decided that the material for the Thermocouple shown in figure 4-3 should be

Copper ᴓ 63 mm We choose it that way because Copper has very good heat dissipation characteristics

and the resistance value is low It can reduce the value of the current enough to make the thermocouple to

create heat

Fig 4-3 Thermocouple

To the thermocouple we attach the tungsten filament boat We need to take notice of materials to be

used in this design because when using high current the tungsten filament boar will heat up and so the

material must be able to keep up with the heating potential of tungsten and has a low coefficient of heat

dissipation to avoid the tungsten to fail when heating up and therefore not evaporating Considering all

this we decide to use Stainless Steel

Because this clamp will be assembled inside the chamber after many revisions it was determined it

will have the shape shown in figure 4-4

Fig 4-4 Filament Boat Clamp Design

80

For the tungsten filament boat we bought the product from a distributor The dimensions are

Length 100 mm

Width 10 mm

Height 1 mm

Our thermocouple is 15 in but the pass way C is 4 in so we need to attach a Flange that connects

15in to 4in Because these specifications are quite difficult to achieve by Milling we had to use

electrical wire cutting

For the laser clamping system where the laser that is going to be AR coated will be placed will be

connected to pass way A the assembly is shown in figure 4-5 below

Fig 4-5 Cover Assembly

For this design we used an O-ring instead of a gasket so as to save time The design of the assembly

where the laser will be placed is shown in figure 4-6

Fig 4-6 Upper Cover Inner Assembly

D

E

F

81

Point D is the plate in the assembly where the laser diode will be fixed Because of the easy

processing we decide to use Aluminum and it is screwed to the top cover Point E is the connection for

the Quartz crystal resonator and it is designed in the same as point F in this way the results of the quartz

microbalance system will be more accurate in real time Point F is the final resting place for the laser

diode We use a Thor Labs Base with dimensions of ᴓ 9mm and ᴓ 56mm for two different size laser

diodes It just needs to be plugged in for easy installation

From figure 4-6 we know that the system needs signal system connections and because of the

change in temperature inside the chamber this could affect the functioning of the quartz microbalance so

we also need to install water tubes for cooling This is shown in figure 4-7 below

Fig 4-7 Diagram of Upper Cover Connections

In figure 4-8 we show the Feed through connections and their functions

Fig 4-8 Feed through Diagram

82

1 SQM-160 wire 5 Laser Connection 1 (Vin)

2 SQM-160 (G) 6 Laser Connection 2 (G)

3 K-Type-1 7 Laser Connection 3 (PD)

4 K-Type-2 8 Not In Use

The fully assembled chamber is shown in figure 4-9

Fig 4-9 Fully Assembled Chamber

422 Quartz Crystal Microbalance

For measuring the deposition on our target for coating we used the Inficon SQM-160 RateThickness

Monitor It is an easy to use instrument for measuring many types of thin-film coatings as shown in

figure 4-10

(a) Front Panel (b) Back Panel

Fig 4-10 Inficon SQM-160

83

Table 4-1 shows the technical specifications for this equipment

Number of sensors 2 Standard 4 additional optional

Sensor Frequency Range 40 MHz ~ 60 MHz

Reference Frequency Accuracy 002

Thickness Display Resolution 1 Aring

Thickness Resolution 015 Aring (Std) 0037 Aring (Hi Res)

Density of Stored Films 05-9999 gmcc

Tooling 10-399

Z-Factor 010-1000

Final Thickness 0000-9999k Aring

Measurement Period 15 to 2 sec

Simulation Mode Yes

Frequency Mode Yes

Rate Resolution 011 Arings

Dual Crystal Yes

Etch Mode Yes

Crystal Tooling 10-399

Crystal Fail Min Max 40 to 60 MHz 41 to 61 MHz

Power 100-120 200-240~plusmn10 nominal 20W

Operation Environment 0degC ~ 50degC

0 ~ 80 RH non-condensing

0 ~ 2000 meters

Class 1 Equipment

Pollution Degree 2

Rack Dimensions 885mm x 2127mm x 1969mm

Weight 27 kg

Table 4-1 Inficon SQM-160 RateThickness Monitor Specs

84

To the SQM-160 we need to connect an Oscillator We use the Sigma Instruments Remote Oscillator

Ser No 2 268 as shown in figure 4-11

Fig 4-11 Sigma Instruments Remote Oscillator

The connections diagram is shown in figure 4-12

Fig 4-12 SQM-160 Connections Diagram

85

423 Turbo Pump

For our experiments we used the Pfeiffer TCP 015 Electronic Drive Unit shown below in figure 4-13

Table 4-2 shows the technical specifications for this equipment

(a) Front Panel (b) Back Panel

Fig 4-13 Pfeiffer TCP 015 Electronic Drive

Connection Voltage (100V) 90-112

Mains Frequency 5060 Hz

Start-up Current 22 A

Nominal Frequency 1500 Hz

Rotation Speed 10V = 1500Hz plusmn2

Analog Output Current 10 V = 25 A plusmn 5

Rotation Speed Switchpoint 750 Hz

Works Setting 8 min

Permissible Ambient Temperature 0degC ~ 40degC

Dimensions Front Panel 1285mm x 1063mm

Insertion Length 227mm

Weight 27 Kg

Table 4-2 Pfeiffer TCP 015 Electronic Drive Specs

86

The connections diagram is shown in figure 4-14

Fig 4-14Connections Diagram for Pfeiffer TCP 015

To measure the pressure inside the chamber we use the Granville Phillips 375 Convectron Vacuum

Pressure Controller shown in figure 4-15

(a) Front Panel (b) Back Panel

Fig 4-15 Granville Phillips 375 Convectron

87

Its dimensions are shown in figure 4-16

Fig 4-16 Dimensions of Convectron

Table 4-3 shows the technical specifications for this equipment

Table 4-3 Granville Phillips 375 Convectron Vacuum Pressure Controller Specs

88

424 Multimeter

For our experiment we used the Keithley 2000 Digital Multimeter as shown in figure 4-17

(a) Front Panel (b) Back Panel

Fig 4-17 Keithley Model 2000 6-12-Digit Digital Multimeter

Its technical specifications are shown in table 4-4

Table 4-4 Keithley Model 2000 6-12-Digit Digital Multimeter Specs

89

43 Experiment Procedure

1 Connecting together the equipment and the chamber

(1) We first connect the resonator to the thickness monitor and connect the other side to the

chamber

(2) We now connect the flexible tubes to the turbo pump on one side and to the chamber on the

other

(3) We need to check that tubes are tightly connected to avoid any leaks in the vacuum pumping

process which will not allow us to get to our goal of Torr As shown in figure 4-18

(4) Connect the convectron to the system as shown in figure 4-19

Fig 4-18 checking for leaks using alcohol

Fig 4-19 Convectron attached to System

90

(5) Attach the clamps of the Multimeter to the bottom of the chamber as shown in figure 4-20

(6) Place the Quartz crystal in place

(7) Close tight vacuum chamber

(8) Connect all electrical appliances to power source

Fig 4-20 Multimeter Connections

2 Starting up the System

(1) We turn on all the devices as such Check all systems are ready to function Reset all values

that might be left over from previous tests

(2) Start the thickness monitor and set all values for this experiment In our case we got to testing

the system but not actual coating So we used the simulation mode of the thickness monitor as

shown in figure 4-21

Fig 4-21 Simulation Mode

91

(3) Start the turbo pump Make sure the lid on the vacuum chamber is tightly closed

(4) Start convectron and record initial pressure

(5) Start Multimeter and record initial current

3 Coating Process

(1) If we have the deposition material inside the filament boat the power source for the high

current must be started as well

(2) Record all initial values for thickness current pressure

(3) For an ideal experiment we need a thickness of around 101 nm a pressure of Torr and

a current of 300 A

44 Results

From previous experiments we have shown that we can turn a LED into a laser by means of AR

Coating In figure 4-22 shown below we can compare the actual results of a Diode before and after AR

coating From the blue line we can see that when the diode is at a current of 15mA its light will change

from LED to laser and if we look at the red line its critical current is around 30 to 35 mA

Fig 4-22 AR Coating Comparison for Laser Diodes

This means that the light emitted is not as strong as if the diode had been coated because inside the

chamber there must be some excitation first so the reflectivity of both sides inside the diode must be high

So because of the coating in one of the sides we have opened a door and let the light come out so the

critical current is risen as such and will be higher value than that of before the coating

92

In the following figures we can see the difference between before and after coating in a material The

thickness is around 1016 nm for this material

Fig 4-23 Before Coating

Fig 4-24 After Coating

93

Chapter 5 CONCLUSIONS AND RECOMMENDATIONS

51 Conclusions

For the first part of this independent study taking into consideration the data that came out of our

research and that sent by the provider we can say

1 SUM 23 after heat treatment will unexpectedly develop cracking in the middle of the tensile

testing process and suddenly break

2 Itrsquos possible that in the process of heat treatment to the SUM 23 material the treatment was not

uniform and this will create a pre-loaded moment force on one side that pushes on the other side

of the specimen resulting in material deformation

3 In the process of attaching the strain gauges to the materials it is very easy to make errors due to

poor adhesion or sudden removal in the tensile testing process

For our second part of the independent study the following can be made

1 At the beginning of this independent study we had no idea what Bose-Einstein Condensate was

or what was its purpose After much literature we finally comprehended the basic principles to

put into practice for our research

2 Our systemrsquos basic working principles and equipmentrsquos complexity are a little difficult to grasp

but hopefully we were able to understand enough of it

3 Theoretically from relation between the power and current we can know the advantages and

disadvantages of AR Coating

4 We were able to assemble the system and run test on its functions Even though we were able to

do this there is still much more work left to do with this system

52 Recommendations

For the Tensile Testing the following can be said

1 Ask the provider to check on the process of heat treatment on the SUM 23 material and give

them the information we have gathered through our test so they can correct for the mechanical

properties found if any change is needed

2 To avoid the problem of the inaccuracy of the poor adhesion of strain gauges we can attach

multiple strain gauges to the same one specimen so as to correlate data and improve our results

For the AR Coating the following can be said

1 We need to make sure that there are no physical defects on the main body of the chamber so as to

achieve maximum efficiency in the vacuum process If there was then the vacuum will arrive to

certain point and then start to decrease

2 It would be preferable to add some sort of visual aid that will allow the user to check the inside of

the chamber without actually opening it This will help us determine at what times we should

manipulate the current to better evaporate the substrate

94

REFERENCES

[1] A L Window Strain Gauge Technology Elsevier Applied Science London and New York 2nd

Edition 1992

[2] CC Perry and HR Lissner Strain Gauge Primer McGraw-Hill Book Co Inc New York 1955

[3] James W Dally William F Riley McGraw-Hill 1978

[4] University of Colorado Boulder BEC - What is it and where did the idea come from

httpwwwcoloradoeduphysics2000becwhat_is_ithtml

[5] Ultraslow Light amp Bose-Einstein Condensates Two-way Control with Coherent Light amp Atom

Fields Harvard Hau Lab Dr Lene Vestergaard Hau Optics amp Photonics News 16 1995

[6] The Art of Taming Light Ultra-slow and Stopped Light Harvard Hau Lab Dr Lene

Vestergaard Hau Europhysics News 2004

[7] Nonlinear Optics Shocking Superfluids Harvard Hau Lab Dr Lene Vestergaard Hau Nature

Physics 2007

[8] Model P3 Strain Indicator and Recorder Instruction Manual Vishay Micro-Measurements 2005

[9] Granville-Phillips Series 375 Convectron Vacuum Gauge Controller Instruction Manual Brooks

Automation 2008

[10] Effect of Film Thickness on the Validity of the Sauerbrey Equation for Hydrated Polyelectrolyte

Films Vogt Lin Wu White 2004

[11] Quartz Crystal Microbalance Study of DNA Immobilization and Hybridization for DNA Sensor

Development Chang Zhao 2008

[12] Installation of Strain Gages with SR-4 PrecoatAdhesive Vishay Micro-Measurements 2005

[13] Strain Gauge Measurement ndash A Tutorial National Instruments 1998

[14] Correlation between Vickers Hardness Number and Yield Stress of Cold-Formed Products

Yavuz Tekkaya

[15] httpsenwikipediaorg

Page 39: PC Hinge Materials Testing and AR Laser Diode Coating

39

A vacuum evaporation system is shown in figure 2-24

Fig 2-24 Vacuum Evaporation System

Rough Vacuum 760 ~ 1 torr

Medium Vacuum 1 ~ torr

High Vacuum ~ torr

Ultra-High Vacuum Lower than torr

Table 2-3 Classification of Vacuum

For our study we need to use a Turbo Pump A regular turbo pump is shown in figure 2-25

Fig 2-25 Turbo Pump

For our research we used the Pfeiffer TCP 015 Electronic Drive Unit and Granville Phillips 375

Convectron shown below in figure 2-26

40

Fig 2-26 Control and Measurement Equipment

The electronic drive controls the turbo pump and the Convectron measures the pressure inside our

chamber The turbo pump is a type of vacuum pump used to maintain high vacuum Most turbo pumps

are centrifugal When we start the pumping we need to use a mechanical pump so as to decrease the

pressure inside the system from constant atmospheric pressure to torr and then the use dispersion

pump to continue the vacuum until we get to the desired pressure We need to notice though when we

start the dispersion pump we canrsquot turn off the mechanical pump and they both need to run together If

we need to turn off the pumping we first turn off the dispersion pump wait for it to completely stop and

then turn off the mechanical pump

Our completely assembled system is shown in figure 2-27 below

Fig 2-27 Complete System

41

Chapter 3 TENSILE TESTING IN DEPTH

31 Experimentrsquos Purpose and Principles

By means of Universal testing machine and Strain gauges we were able to observe discuss and

analyze the phenomena created when a specimen of certain material is manipulated under an external load

and determine the stress strain and deformation values later we can use the graphing methods of

stress-strain diagram to describe it

The main point of this experiment is that after the tensile specimen is tested use computer analysis

and the actual strain data and after statistical adjustment make the final results report (Tensile testing

experiment is in accordance with ASTM E8)

32 Experimentrsquos Equipment

321 Universal Testing Machine

For the materials testing experiment part of this research we use a Universal Testing Machine as

shown in figure 31 The maximum load it can apply is 100 Ton After the test specimen is secured on the

device with the use of instrumentation the load exerted and the effects of this become apparent on the

specimen and even the smallest of changes can be recorded For our research we used the Chun Yen

Testing Machines Co Ltd 100 Ton Micro Computer Universal Tensile Tester

Fig 31 Universal Testing Machine

42

Table 31 shows the specifications for this machine

Max Capacity 100 Ton

Accuracy plusmn1

Tension (mm) Max Space 1150mm

Grip for Rod 20-70mm

Ram Stroke 250mm

Effective Column Interval 940mm

Crosshead Speed 300mmmin

Testing Speed 0-50mmmin

Volume of Machine 1700times1000times3350mm(LtimesWtimesH)

Volume of Control Panel 1000times800times1500mm(LtimesWtimesH)

Weight 8000kg

Power 3∮220V 20A

Computer AMD K6-2-350

OS Windows XP

Screen 15rdquo CRT

Table 3-1 Chun Yen Testing Machine Specs Table

The connections diagram is shown in figure 3-2

Fig 3-2 Diagram for System Connections

43

When the test specimen is placed when the external force is applied the Load Cell can measure the

size of the applied force and the Encoder measures the expansion rate of change The Local Controller

receives all the information from the 2 units after arranging the results they are displayed in the

computer and they can be afterwards submitted for more complex analysis such as Finite Element

Analysis and we can get the Stress-Strain Diagram

322 Strain Measurement Equipment

The equipment used in our research provides a four-channel measurement that means we can use up

to 4 strain gauges at a time to do our measurements and provides 3 different bridge arrangements as

shown in figure 3-3

(a) (b) (c)

Fig 3-3 Input Connections for Strain Indicator

Figure 3-3 (a) is the Quarter Bridge (b) is the Half Bridge and (c) is the Full Bridge and Transducers

For our study we used the Quarter Bridge and use the Strain Gauge values to decide the position of the

connecting wires The Strain indicator is shown in figure 3-4

Fig 3-4 Vishay Micro-Measurements Model P3 Strain Indicator and Recorder

44

Input Connections Tool Free eccentric lever release

4-channel input

Wire diameter16-28AWG

Bridge Configurations Quarter- Half- and Full Bridge

Bridge Impedance 60-2000Ω

Display 128 64 pixel FSTN positive gray LCD

Data Conversion AD Converter filter

Measurement Range Resolution Strain Range plusmn155mVV

Resolution plusmn00005mVV

Measurement Accuracy plusmn01 of reading plusmn3 counts

Gage Factor Control 0500-9900

Balance Control Software either manual or automatic

Bridge Excitation 15VDC nominal

Communication Interface USB Cable Included

Data Storage Removable Media Card

Shunt Calibration Across bridge completion resistors controlled

by software When Gage Factor=200

120Ω350Ω1000Ω

Analog Output Value 0 to 25V max

Ranges plusmn320 microε plusmn3200 microε plusmn32000 microε

Error 05 output voltage +5mV

Max Error 14 output voltage + 20mV

Update rate 480 samplessec

Output Load 2000Ω

Power Battery Two Alkaline D cells

Battery life 400 hours typ

USB 5V 100mA

Operational Environment Temperature 0-50

Humidity Up to 90 Non-condensing

Case Aluminum Alloy

Size and Weight 228times152times152(mm) 20(kg)

Table 3-2 Vishay Micro-Measurements Model P3 Strain Indicator and Recorder Specs

45

323 Strain Gauge

The strain gaugersquos main basic principle is to use a resistancersquos characteristics to measure the strain

The inside connections of the strain indicator are shown in figure 3-5

Fig 3-5 Inner Connections

As shown above this is a quarter-bridge connection We connect equal-length 3 wires to the 2

connections allowed by the strain gauge wire 1 and 3 can be used to cancel out the effects of temperature

to the resistance and because of the addition of wires 1 and 3 wire 2 can directly measure the experiment

results from the strain gauge and therefore the strain developed with no influence of temperature

If there were no two measuring leads then the relations will be

R 4 =R g +2R L

Where Rg is the Strain Gauge Value and RL is the wire resistance then

4

4

R

R=

Lg

g

RR

R

2

=

gL

gg

RR

RR

21

amp

4

4

R

R=

g

g

R

R(1- L)

Where L is the Signal Loss Factor and so

L =gL

gL

RR

RR

21

2

g

L

R

2R if

g

L

R

2Rltlt1

46

(Actual Value R g =120R L =08g

L

R

2Ris always much smaller than 1)

R 4 =R g +2R LR 2 =R 3 =rR gR 1 =R g 32 RR =0

V 0 =V 2)1( r

r

(

4

4

R

R-

1

1

R

R)

The first term describes loss attenuation effects second term describes loss of balancing capabilities

effects

V 0 =V 2)1( r

r

[

)2

(Lg

g

RR

R

+

T

Lg

g

RR

R

)

2( + T

Lg

L

RR

R

)

2

2( -(

g

g

R

R) T ]

The first term describes loss attenuation effects and loss of balancing capabilities effects the second

third and fourth terms describe the temperature effects on the wire

For the three-wire method we have

L =gL

gL

RR

RR

1

g

L

R

R if

g

L

R

Rltlt1

V 0 =V 2)1( r

r

[

)(Lg

g

RR

R

+

T

Lg

g

RR

R

)( + T

Lg

L

RR

R

)

2( -

T

Lg

g

RR

R

)( - T

Lg

L

RR

R

)

2( ]

V 0 = V2)1( r

r

)(

Lg

g

RR

R

In the last four terms inside parenthesis we can see the effects of temperature being cancelled out and the

effect on first term is not great so this is the reason why in our research we use three wires

47

324 Specimen Measurements

The tensile specimens used in this research are compliant of ASTM E8 Tensile parameters as shown

in figure 3-6

Fig 3-6 Tensile Specimen

Diameter

D(mm)

Gauge

Length

G(mm)

Smallest

Arc

Radius

R(mm)

Shortest

Area

A(mm)

Total

Length

L(mm)

Clamping

Area

Length

B(mm)

Clamping

Area

Diameter

C(mm)

Bar 125 02 625 01 gt10 gt75 ~ 145 ~ 35 20

Table 3-3 Specifications for Round Bar

33 Experiment Procedure

1 Attaching the Strain Gauge to the Tensile Specimen

(1) Prepare 1 ASTM E8 compliant tensile specimen round bar as shown in figure 3-7

(2) Prepare Strain Gauge as those described in table 3-4

(3) Prepare other consumables and adhesive agent such as epoxy adhesive or

cyanoacrylate adhesive as shown in figure 3-8

48

Fig 3-7 Actual Tensile Specimen

Fig 3-8 Other Materials Used (Such as Alcohol gauze transparent tape adhesive)

Gage Type

EA-06-120LZ-120E

Resistance in ohms at 24∘C

1200plusmn03

Gage Factor at 24∘C

2075plusmn05

Transverse Sensitivity at 24∘C

(+07plusmn02)

Table 3-4 Specifications for Strain Gauge

2 Attaching Strain Gauge

As shown in following figures we shall explain the attachment of the strain gauge

(1) Use sand paper and a rasp to clean thoroughly the surface where the strain gauge will be

attached to

49

(a)

(2) Use alcohol to wash the surface where the strain gauge will be attached and use gauze to rub

it off

(b)

(3) Find a clean surface and clean it with alcohol and gauze

(c)

(4) Place the strain gauge in the clean surface Use a piece of transparent tape on top of the strain

gauge after securely placed rip it off the surface carefully

50

(d)

(5) Use a piece of white paper to mark the place where the strain gauge will be attached and in

this way we can make sure that the strain gauge will be placed as horizontally and vertically

correct as possible

(e)

(6) In the place where we had our mark place the strain gauge

(f)

(7) Carefully lift one side of the tape and apply some of the adhesive agent to both the strain

gauge and specimenrsquos surface

(g)

51

(8) We need to make sure that the gauge and the specimen will be firmly attached so we gently

apply pressure with our thumb

(h)

(9) After the adhesive is fully dry we can carefully rip off the tape

(i)

(10) We need to do the whole process twice one for the horizontally placed strain gauge and one

for the vertically placed strain gauge

52

(j)

(11) We now proceed to solder the wires to the strain gauge

(k)

(12) After soldering we use a Volt Multimeter to measure that there is no contact between wires

If there is none then the specimen is ready for testing

(l)

(13) We now need to measure a 5cm distance and mark it to check and compare the elongation

before and after the tensile testing

(m)

53

Fig 3-9 Specimen-Strain Gauge Process

3 Tensile Test

(1) Enter the computer application that controls the tensile testing machine

(2) Turn on the tensile testing machine main switch

(3) Adjust the hydraulic pump to go back to its original position

(4) Bring the lowering motor down to a distance enough so as to attach the tensile specimen to the

system open the clamps and secure the specimen

(a)

(5) Connect all the necessary wires to the strain indicator equipment

54

(b)

(6) Start the ascending motor and wait for the expansion

(c)

Fig 3-10 Specimen-Tensile Testing Process

4 Start the Test

(1) Enter the software application and enter some variables needed for the experiment in the

specific screen

(2) Go back to the main screen and press the [測試] (measure) button to start the test and auto

recording in the software

(3) After the specimen breaks the mechanical device will automatically stop and ask the user to

enter the total displacement We take out the specimen from the testing machine and adjust the

machinersquos position back to its original position

(4) Save the results information

(5) Record the results from the strain indicator

34 Results

From this experiment we can get the Poissonrsquos Ratio Youngrsquos Modulus and Yield Strength etc and

because of the slippage phenomenon in the clamp at the moment of the test then the Elastic Limit will

display some yield phenomena So omit any undesirable results we just take the Yield portion of the

results as reference

In the process of the experiment the most important part to attend to is the attaching of the strain

gauge because the gaugersquos purpose is to measure the strain developed during the test and this strain

might be very small If the gaugersquos angle change during the test ie is not well attached this will affect

the accuracy of the measurements of Poissonrsquos ratio and Youngrsquos modulus

55

The materials provided by the manufacturer are SUM 23 and SUM 43 steel round bars and these two

types of materials have been through different heat treatment processes so they can be sub-divided

further into untreated material heat-treated material and black surface heat treated material for the two

materials with heat treatment the treatment process and finished are different In the end we only have

the mechanical properties that were calculated after our research of these materials

All of the specifications are identical to those shown in figure 3-6

341 SUM 23

Fig 3-11 SUM 23 Untreated Material

Number 7 10

Hardness(HRB) 74 75

Yield Stress (MPa) 448 440

Tensile Strength (MPa) 544 560

Poissonrsquos Ratio 029 027

Youngrsquos Modulus (GPa) 203 210

Cut-off Area Shrinking () 42 41

Elongation () 1125 1011

Table 3-5 Mechanical Properties of SUM 23 Untreated

56

Stress-Strain Diagram

(a)

(b)

57

Fig 3-12 Stress-Strain Diagrams for (a) 7 Round Bar and (b) 10 Round Bar

Cut-Off Area

(a)

(b)

Fig 3-13 Cut-Off Area of (a) 7 Round Bar and (b) 10 Round Bar

58

SUM 23 Nickel Round Bar

Fig 3-14 SUM 23 Nickel Material

Number 1 2 3 4

Hardness(HRB) 48 50 49 48

Yield Stress (MPa) 370 370 380 400

Tensile Strength (MPa) 455 451 450 450

Poissonrsquos Ratio 028 046 029 026

Youngrsquos Modulus (GPa) 243 303 246 206

Cut-off Area Shrinking () 803 803 726 601

Elongation () 566 65 602 647

Table 3-6 Mechanical Properties of SUM 23 Nickel

59

Stress-Strain Diagram

(a)

60

(b)

(c)

(d)

61

Fig 3-15 Stress-Strain Diagrams for (a) 1 Round Bar (b) 2 Round Bar (c) 3 Round Bar and (d)

4 Round Bar

Cut-Off Area

(a)

(b)

62

(c)

(d)

Fig 3-16 Cut-Off Area of (a) 1 Round Bar (b) 2 Round Bar (c) 3 Round Bar and (d) 4 Round

Bar

63

SUM 23 Black Surface Round Bar

Fig 3-17 SUM 23 Black Surface Material

Number 1 2 3

Hardness(HRB) 51 50 51

Yield Stress (MPa) 378 371 369

Tensile Strength (MPa) 467 465 464

Poissonrsquos Ratio 03 016 04

Youngrsquos Modulus (GPa) 215 266 266

Cut-off Area Shrinking () 986 94 848

Elongation () 748 805 761

Table 3-7 Mechanical Properties of SUM 23 Black Surface Material

64

Stress-Strain Diagram

(a)

(b)

65

(c)

Fig 3-18 Stress-Strain Diagrams for (a) 1 Round Bar 2 Round Bar and (c) 3 Round Bar

Cut-Off Surface

(a)

66

(b)

(c)

Fig 3-19 Cut-Off Surface of (a) 1 Round Bar 2 Round Bar and (c) 3 Round Bar

67

342 SUM 43

Fig 3-20 Untreated SUM 43 Untreated Material

Number 1 5

Hardness(HRB) 76 75

Yield Stress (MPa) 572 594

Tensile Strength (MPa) 743 785

Poissonrsquos Ratio 027 029

Youngrsquos Modulus (GPa) 200 202

Cut-off Area Shrinking () 338 2944

Elongation () 857 894

Table 3-8 Mechanical Properties of SUM 43 Untreated

68

Stress-Strain Diagrams

(a)

(b)

Fig 3-21 Stress-Strain Diagrams for SUM 43 (a) 1 Round Bar and (b) 5 Round Bar

69

Cut-Off Area

(a)

(b)

Fig 3-22 Cut-Off Area of SUM 43 (a) 1 Round Bar and (b) 5 Round Bar

70

SUM 43 Nickel Round Bar

Fig 3-23 SUM 43 Nickel Material

Number 4 5

Hardness(HRB) 51 50

Yield Stress (MPa) 1580 1544

Tensile Strength (MPa) 1639 1625

Poissonrsquos Ratio 03 028

Youngrsquos Modulus (GPa) 194 201

Cut-off Area Shrinking () 1697 137

Elongation () 376 265

Table 3-9 Mechanical Properties of SUM 43 Nickel

71

Stress-Strain Diagrams

(a)

(b)

Fig 3-24 Stress-Strain Diagrams for (a) 4 Round Bar and (b) 5 Round Bar

72

Cut-Off Area

(a)

(b)

Fig 3-25 Cut-Off Area of (a) 4 Round Bar and (b) 5 Round Bar

73

SUM 43 Black Surface Material

Fig 3-26 SUM 43 Black Surface Material

Number 3 5

Hardness(HRB) 56 56

Yield Stress (MPa) 1416 1361

Tensile Strength (MPa) 1591 1402

Poissonrsquos Ratio 029 031

Youngrsquos Modulus (GPa) 200 202

Cut-off Area Shrinking () 139 124

Elongation () 24 24

Table 3-10 Mechanical Properties of SUM 43 Black Surface Material

74

Stress-Strain Diagrams

0 2 4 6 8 10 12 14

-200

0

200

400

600

800

1000

1200

1400

1600

1800

應力 (MPa)

應變()

(a)

0 2 4 6 8 10

-200

0

200

400

600

800

1000

1200

1400

1600

應力

(MPa)

位移 ()

(b)

Fig 3-27 Stress-Strain Diagrams for (a) 3 Round Bar and (b) 5 Round Bar

(Note These curves were formulated using Visual Solutions Inc VisSim Software)

75

Cut-Off Area

(a)

(b)

Fig 3-28 Cut-Off Area of (a) 3 Round Bar and (b) 5 Round Bar

76

The force value (N) was retrieved from the Universal Testing Machine

The Poissonrsquos Ratio (ε) is calculated as

ε =

the values for the Poissonrsquos Ratio are in average around 0297

The Youngrsquos Modulus (E) is calculated as

E =

Where

Stress =

Cross-sectional Area =

where D is the Diameter

The value for D was in average around 1258 mm

The values shown by the computer because there is Slippage phenomena between the Clamp and the

specimen will not be taken into consideration for the elongation strain and Youngrsquos modulus and we will

refer to the values that we have meticulously calculated

77

Chapter 4 AR COATING IN DEPTH

41 Experimentrsquos Purpose and Principles

By means of a vacuum chamber and several other instruments we intend to apply Anti-Reflective

Coating using deposition process to a laser diode and in this way reduce its refraction so as to make it

lose less light in the process of amplification and we can control certain wavelengths we want produced

for certain desired applications in our case we are attempting to re-create a Bose-Einstein Condensate

An optimal BEC apparatus is shown in figure 4-1

Fig 4-1 BEC Apparatus

The main point of this experiment is to build a vacuum chamber system attach all the instrumentation

needed (Vacuum pump deposition meter and voltmeter) and use it to apply AR coating to a laser diode

After we have accomplished the AR coating other team will be in charge of designing the BEC apparatus

and use the results of our research

78

42 Experimentrsquos Equipment

421 Vacuum Chamber

For this research we designed a vacuum chamber whose main body is shown in figure 4-2 Its

dimensions are

Width 240 mm

Length 240 mm

Height 200 mm

Outer Diameter 4 in

Inner Diameter 15 in

Fig 4-2 Vacuum Chamber Main Body

The chamber is made up of 6 pass ways pass way A is the connection with the Laser Deposition

Equipment pass way B is the connection with the Turbo Pump and pass way C is for the connection with

the Deposition Source

A

C

B

79

Pass way C is for the deposition source as mentioned above This is a system where a thermal

resistance is heated by passing a high current through it which heats up a filament boat (made of tungsten)

where the material to be evaporated is place We control the temperature as such that the material will

evaporate and the heat will not cause the filament boat to crack

Because P = Isup2 R (where P is power I is current and R is resistance) to avoid the current to flow

where it is not desired we decided that the material for the Thermocouple shown in figure 4-3 should be

Copper ᴓ 63 mm We choose it that way because Copper has very good heat dissipation characteristics

and the resistance value is low It can reduce the value of the current enough to make the thermocouple to

create heat

Fig 4-3 Thermocouple

To the thermocouple we attach the tungsten filament boat We need to take notice of materials to be

used in this design because when using high current the tungsten filament boar will heat up and so the

material must be able to keep up with the heating potential of tungsten and has a low coefficient of heat

dissipation to avoid the tungsten to fail when heating up and therefore not evaporating Considering all

this we decide to use Stainless Steel

Because this clamp will be assembled inside the chamber after many revisions it was determined it

will have the shape shown in figure 4-4

Fig 4-4 Filament Boat Clamp Design

80

For the tungsten filament boat we bought the product from a distributor The dimensions are

Length 100 mm

Width 10 mm

Height 1 mm

Our thermocouple is 15 in but the pass way C is 4 in so we need to attach a Flange that connects

15in to 4in Because these specifications are quite difficult to achieve by Milling we had to use

electrical wire cutting

For the laser clamping system where the laser that is going to be AR coated will be placed will be

connected to pass way A the assembly is shown in figure 4-5 below

Fig 4-5 Cover Assembly

For this design we used an O-ring instead of a gasket so as to save time The design of the assembly

where the laser will be placed is shown in figure 4-6

Fig 4-6 Upper Cover Inner Assembly

D

E

F

81

Point D is the plate in the assembly where the laser diode will be fixed Because of the easy

processing we decide to use Aluminum and it is screwed to the top cover Point E is the connection for

the Quartz crystal resonator and it is designed in the same as point F in this way the results of the quartz

microbalance system will be more accurate in real time Point F is the final resting place for the laser

diode We use a Thor Labs Base with dimensions of ᴓ 9mm and ᴓ 56mm for two different size laser

diodes It just needs to be plugged in for easy installation

From figure 4-6 we know that the system needs signal system connections and because of the

change in temperature inside the chamber this could affect the functioning of the quartz microbalance so

we also need to install water tubes for cooling This is shown in figure 4-7 below

Fig 4-7 Diagram of Upper Cover Connections

In figure 4-8 we show the Feed through connections and their functions

Fig 4-8 Feed through Diagram

82

1 SQM-160 wire 5 Laser Connection 1 (Vin)

2 SQM-160 (G) 6 Laser Connection 2 (G)

3 K-Type-1 7 Laser Connection 3 (PD)

4 K-Type-2 8 Not In Use

The fully assembled chamber is shown in figure 4-9

Fig 4-9 Fully Assembled Chamber

422 Quartz Crystal Microbalance

For measuring the deposition on our target for coating we used the Inficon SQM-160 RateThickness

Monitor It is an easy to use instrument for measuring many types of thin-film coatings as shown in

figure 4-10

(a) Front Panel (b) Back Panel

Fig 4-10 Inficon SQM-160

83

Table 4-1 shows the technical specifications for this equipment

Number of sensors 2 Standard 4 additional optional

Sensor Frequency Range 40 MHz ~ 60 MHz

Reference Frequency Accuracy 002

Thickness Display Resolution 1 Aring

Thickness Resolution 015 Aring (Std) 0037 Aring (Hi Res)

Density of Stored Films 05-9999 gmcc

Tooling 10-399

Z-Factor 010-1000

Final Thickness 0000-9999k Aring

Measurement Period 15 to 2 sec

Simulation Mode Yes

Frequency Mode Yes

Rate Resolution 011 Arings

Dual Crystal Yes

Etch Mode Yes

Crystal Tooling 10-399

Crystal Fail Min Max 40 to 60 MHz 41 to 61 MHz

Power 100-120 200-240~plusmn10 nominal 20W

Operation Environment 0degC ~ 50degC

0 ~ 80 RH non-condensing

0 ~ 2000 meters

Class 1 Equipment

Pollution Degree 2

Rack Dimensions 885mm x 2127mm x 1969mm

Weight 27 kg

Table 4-1 Inficon SQM-160 RateThickness Monitor Specs

84

To the SQM-160 we need to connect an Oscillator We use the Sigma Instruments Remote Oscillator

Ser No 2 268 as shown in figure 4-11

Fig 4-11 Sigma Instruments Remote Oscillator

The connections diagram is shown in figure 4-12

Fig 4-12 SQM-160 Connections Diagram

85

423 Turbo Pump

For our experiments we used the Pfeiffer TCP 015 Electronic Drive Unit shown below in figure 4-13

Table 4-2 shows the technical specifications for this equipment

(a) Front Panel (b) Back Panel

Fig 4-13 Pfeiffer TCP 015 Electronic Drive

Connection Voltage (100V) 90-112

Mains Frequency 5060 Hz

Start-up Current 22 A

Nominal Frequency 1500 Hz

Rotation Speed 10V = 1500Hz plusmn2

Analog Output Current 10 V = 25 A plusmn 5

Rotation Speed Switchpoint 750 Hz

Works Setting 8 min

Permissible Ambient Temperature 0degC ~ 40degC

Dimensions Front Panel 1285mm x 1063mm

Insertion Length 227mm

Weight 27 Kg

Table 4-2 Pfeiffer TCP 015 Electronic Drive Specs

86

The connections diagram is shown in figure 4-14

Fig 4-14Connections Diagram for Pfeiffer TCP 015

To measure the pressure inside the chamber we use the Granville Phillips 375 Convectron Vacuum

Pressure Controller shown in figure 4-15

(a) Front Panel (b) Back Panel

Fig 4-15 Granville Phillips 375 Convectron

87

Its dimensions are shown in figure 4-16

Fig 4-16 Dimensions of Convectron

Table 4-3 shows the technical specifications for this equipment

Table 4-3 Granville Phillips 375 Convectron Vacuum Pressure Controller Specs

88

424 Multimeter

For our experiment we used the Keithley 2000 Digital Multimeter as shown in figure 4-17

(a) Front Panel (b) Back Panel

Fig 4-17 Keithley Model 2000 6-12-Digit Digital Multimeter

Its technical specifications are shown in table 4-4

Table 4-4 Keithley Model 2000 6-12-Digit Digital Multimeter Specs

89

43 Experiment Procedure

1 Connecting together the equipment and the chamber

(1) We first connect the resonator to the thickness monitor and connect the other side to the

chamber

(2) We now connect the flexible tubes to the turbo pump on one side and to the chamber on the

other

(3) We need to check that tubes are tightly connected to avoid any leaks in the vacuum pumping

process which will not allow us to get to our goal of Torr As shown in figure 4-18

(4) Connect the convectron to the system as shown in figure 4-19

Fig 4-18 checking for leaks using alcohol

Fig 4-19 Convectron attached to System

90

(5) Attach the clamps of the Multimeter to the bottom of the chamber as shown in figure 4-20

(6) Place the Quartz crystal in place

(7) Close tight vacuum chamber

(8) Connect all electrical appliances to power source

Fig 4-20 Multimeter Connections

2 Starting up the System

(1) We turn on all the devices as such Check all systems are ready to function Reset all values

that might be left over from previous tests

(2) Start the thickness monitor and set all values for this experiment In our case we got to testing

the system but not actual coating So we used the simulation mode of the thickness monitor as

shown in figure 4-21

Fig 4-21 Simulation Mode

91

(3) Start the turbo pump Make sure the lid on the vacuum chamber is tightly closed

(4) Start convectron and record initial pressure

(5) Start Multimeter and record initial current

3 Coating Process

(1) If we have the deposition material inside the filament boat the power source for the high

current must be started as well

(2) Record all initial values for thickness current pressure

(3) For an ideal experiment we need a thickness of around 101 nm a pressure of Torr and

a current of 300 A

44 Results

From previous experiments we have shown that we can turn a LED into a laser by means of AR

Coating In figure 4-22 shown below we can compare the actual results of a Diode before and after AR

coating From the blue line we can see that when the diode is at a current of 15mA its light will change

from LED to laser and if we look at the red line its critical current is around 30 to 35 mA

Fig 4-22 AR Coating Comparison for Laser Diodes

This means that the light emitted is not as strong as if the diode had been coated because inside the

chamber there must be some excitation first so the reflectivity of both sides inside the diode must be high

So because of the coating in one of the sides we have opened a door and let the light come out so the

critical current is risen as such and will be higher value than that of before the coating

92

In the following figures we can see the difference between before and after coating in a material The

thickness is around 1016 nm for this material

Fig 4-23 Before Coating

Fig 4-24 After Coating

93

Chapter 5 CONCLUSIONS AND RECOMMENDATIONS

51 Conclusions

For the first part of this independent study taking into consideration the data that came out of our

research and that sent by the provider we can say

1 SUM 23 after heat treatment will unexpectedly develop cracking in the middle of the tensile

testing process and suddenly break

2 Itrsquos possible that in the process of heat treatment to the SUM 23 material the treatment was not

uniform and this will create a pre-loaded moment force on one side that pushes on the other side

of the specimen resulting in material deformation

3 In the process of attaching the strain gauges to the materials it is very easy to make errors due to

poor adhesion or sudden removal in the tensile testing process

For our second part of the independent study the following can be made

1 At the beginning of this independent study we had no idea what Bose-Einstein Condensate was

or what was its purpose After much literature we finally comprehended the basic principles to

put into practice for our research

2 Our systemrsquos basic working principles and equipmentrsquos complexity are a little difficult to grasp

but hopefully we were able to understand enough of it

3 Theoretically from relation between the power and current we can know the advantages and

disadvantages of AR Coating

4 We were able to assemble the system and run test on its functions Even though we were able to

do this there is still much more work left to do with this system

52 Recommendations

For the Tensile Testing the following can be said

1 Ask the provider to check on the process of heat treatment on the SUM 23 material and give

them the information we have gathered through our test so they can correct for the mechanical

properties found if any change is needed

2 To avoid the problem of the inaccuracy of the poor adhesion of strain gauges we can attach

multiple strain gauges to the same one specimen so as to correlate data and improve our results

For the AR Coating the following can be said

1 We need to make sure that there are no physical defects on the main body of the chamber so as to

achieve maximum efficiency in the vacuum process If there was then the vacuum will arrive to

certain point and then start to decrease

2 It would be preferable to add some sort of visual aid that will allow the user to check the inside of

the chamber without actually opening it This will help us determine at what times we should

manipulate the current to better evaporate the substrate

94

REFERENCES

[1] A L Window Strain Gauge Technology Elsevier Applied Science London and New York 2nd

Edition 1992

[2] CC Perry and HR Lissner Strain Gauge Primer McGraw-Hill Book Co Inc New York 1955

[3] James W Dally William F Riley McGraw-Hill 1978

[4] University of Colorado Boulder BEC - What is it and where did the idea come from

httpwwwcoloradoeduphysics2000becwhat_is_ithtml

[5] Ultraslow Light amp Bose-Einstein Condensates Two-way Control with Coherent Light amp Atom

Fields Harvard Hau Lab Dr Lene Vestergaard Hau Optics amp Photonics News 16 1995

[6] The Art of Taming Light Ultra-slow and Stopped Light Harvard Hau Lab Dr Lene

Vestergaard Hau Europhysics News 2004

[7] Nonlinear Optics Shocking Superfluids Harvard Hau Lab Dr Lene Vestergaard Hau Nature

Physics 2007

[8] Model P3 Strain Indicator and Recorder Instruction Manual Vishay Micro-Measurements 2005

[9] Granville-Phillips Series 375 Convectron Vacuum Gauge Controller Instruction Manual Brooks

Automation 2008

[10] Effect of Film Thickness on the Validity of the Sauerbrey Equation for Hydrated Polyelectrolyte

Films Vogt Lin Wu White 2004

[11] Quartz Crystal Microbalance Study of DNA Immobilization and Hybridization for DNA Sensor

Development Chang Zhao 2008

[12] Installation of Strain Gages with SR-4 PrecoatAdhesive Vishay Micro-Measurements 2005

[13] Strain Gauge Measurement ndash A Tutorial National Instruments 1998

[14] Correlation between Vickers Hardness Number and Yield Stress of Cold-Formed Products

Yavuz Tekkaya

[15] httpsenwikipediaorg

Page 40: PC Hinge Materials Testing and AR Laser Diode Coating

40

Fig 2-26 Control and Measurement Equipment

The electronic drive controls the turbo pump and the Convectron measures the pressure inside our

chamber The turbo pump is a type of vacuum pump used to maintain high vacuum Most turbo pumps

are centrifugal When we start the pumping we need to use a mechanical pump so as to decrease the

pressure inside the system from constant atmospheric pressure to torr and then the use dispersion

pump to continue the vacuum until we get to the desired pressure We need to notice though when we

start the dispersion pump we canrsquot turn off the mechanical pump and they both need to run together If

we need to turn off the pumping we first turn off the dispersion pump wait for it to completely stop and

then turn off the mechanical pump

Our completely assembled system is shown in figure 2-27 below

Fig 2-27 Complete System

41

Chapter 3 TENSILE TESTING IN DEPTH

31 Experimentrsquos Purpose and Principles

By means of Universal testing machine and Strain gauges we were able to observe discuss and

analyze the phenomena created when a specimen of certain material is manipulated under an external load

and determine the stress strain and deformation values later we can use the graphing methods of

stress-strain diagram to describe it

The main point of this experiment is that after the tensile specimen is tested use computer analysis

and the actual strain data and after statistical adjustment make the final results report (Tensile testing

experiment is in accordance with ASTM E8)

32 Experimentrsquos Equipment

321 Universal Testing Machine

For the materials testing experiment part of this research we use a Universal Testing Machine as

shown in figure 31 The maximum load it can apply is 100 Ton After the test specimen is secured on the

device with the use of instrumentation the load exerted and the effects of this become apparent on the

specimen and even the smallest of changes can be recorded For our research we used the Chun Yen

Testing Machines Co Ltd 100 Ton Micro Computer Universal Tensile Tester

Fig 31 Universal Testing Machine

42

Table 31 shows the specifications for this machine

Max Capacity 100 Ton

Accuracy plusmn1

Tension (mm) Max Space 1150mm

Grip for Rod 20-70mm

Ram Stroke 250mm

Effective Column Interval 940mm

Crosshead Speed 300mmmin

Testing Speed 0-50mmmin

Volume of Machine 1700times1000times3350mm(LtimesWtimesH)

Volume of Control Panel 1000times800times1500mm(LtimesWtimesH)

Weight 8000kg

Power 3∮220V 20A

Computer AMD K6-2-350

OS Windows XP

Screen 15rdquo CRT

Table 3-1 Chun Yen Testing Machine Specs Table

The connections diagram is shown in figure 3-2

Fig 3-2 Diagram for System Connections

43

When the test specimen is placed when the external force is applied the Load Cell can measure the

size of the applied force and the Encoder measures the expansion rate of change The Local Controller

receives all the information from the 2 units after arranging the results they are displayed in the

computer and they can be afterwards submitted for more complex analysis such as Finite Element

Analysis and we can get the Stress-Strain Diagram

322 Strain Measurement Equipment

The equipment used in our research provides a four-channel measurement that means we can use up

to 4 strain gauges at a time to do our measurements and provides 3 different bridge arrangements as

shown in figure 3-3

(a) (b) (c)

Fig 3-3 Input Connections for Strain Indicator

Figure 3-3 (a) is the Quarter Bridge (b) is the Half Bridge and (c) is the Full Bridge and Transducers

For our study we used the Quarter Bridge and use the Strain Gauge values to decide the position of the

connecting wires The Strain indicator is shown in figure 3-4

Fig 3-4 Vishay Micro-Measurements Model P3 Strain Indicator and Recorder

44

Input Connections Tool Free eccentric lever release

4-channel input

Wire diameter16-28AWG

Bridge Configurations Quarter- Half- and Full Bridge

Bridge Impedance 60-2000Ω

Display 128 64 pixel FSTN positive gray LCD

Data Conversion AD Converter filter

Measurement Range Resolution Strain Range plusmn155mVV

Resolution plusmn00005mVV

Measurement Accuracy plusmn01 of reading plusmn3 counts

Gage Factor Control 0500-9900

Balance Control Software either manual or automatic

Bridge Excitation 15VDC nominal

Communication Interface USB Cable Included

Data Storage Removable Media Card

Shunt Calibration Across bridge completion resistors controlled

by software When Gage Factor=200

120Ω350Ω1000Ω

Analog Output Value 0 to 25V max

Ranges plusmn320 microε plusmn3200 microε plusmn32000 microε

Error 05 output voltage +5mV

Max Error 14 output voltage + 20mV

Update rate 480 samplessec

Output Load 2000Ω

Power Battery Two Alkaline D cells

Battery life 400 hours typ

USB 5V 100mA

Operational Environment Temperature 0-50

Humidity Up to 90 Non-condensing

Case Aluminum Alloy

Size and Weight 228times152times152(mm) 20(kg)

Table 3-2 Vishay Micro-Measurements Model P3 Strain Indicator and Recorder Specs

45

323 Strain Gauge

The strain gaugersquos main basic principle is to use a resistancersquos characteristics to measure the strain

The inside connections of the strain indicator are shown in figure 3-5

Fig 3-5 Inner Connections

As shown above this is a quarter-bridge connection We connect equal-length 3 wires to the 2

connections allowed by the strain gauge wire 1 and 3 can be used to cancel out the effects of temperature

to the resistance and because of the addition of wires 1 and 3 wire 2 can directly measure the experiment

results from the strain gauge and therefore the strain developed with no influence of temperature

If there were no two measuring leads then the relations will be

R 4 =R g +2R L

Where Rg is the Strain Gauge Value and RL is the wire resistance then

4

4

R

R=

Lg

g

RR

R

2

=

gL

gg

RR

RR

21

amp

4

4

R

R=

g

g

R

R(1- L)

Where L is the Signal Loss Factor and so

L =gL

gL

RR

RR

21

2

g

L

R

2R if

g

L

R

2Rltlt1

46

(Actual Value R g =120R L =08g

L

R

2Ris always much smaller than 1)

R 4 =R g +2R LR 2 =R 3 =rR gR 1 =R g 32 RR =0

V 0 =V 2)1( r

r

(

4

4

R

R-

1

1

R

R)

The first term describes loss attenuation effects second term describes loss of balancing capabilities

effects

V 0 =V 2)1( r

r

[

)2

(Lg

g

RR

R

+

T

Lg

g

RR

R

)

2( + T

Lg

L

RR

R

)

2

2( -(

g

g

R

R) T ]

The first term describes loss attenuation effects and loss of balancing capabilities effects the second

third and fourth terms describe the temperature effects on the wire

For the three-wire method we have

L =gL

gL

RR

RR

1

g

L

R

R if

g

L

R

Rltlt1

V 0 =V 2)1( r

r

[

)(Lg

g

RR

R

+

T

Lg

g

RR

R

)( + T

Lg

L

RR

R

)

2( -

T

Lg

g

RR

R

)( - T

Lg

L

RR

R

)

2( ]

V 0 = V2)1( r

r

)(

Lg

g

RR

R

In the last four terms inside parenthesis we can see the effects of temperature being cancelled out and the

effect on first term is not great so this is the reason why in our research we use three wires

47

324 Specimen Measurements

The tensile specimens used in this research are compliant of ASTM E8 Tensile parameters as shown

in figure 3-6

Fig 3-6 Tensile Specimen

Diameter

D(mm)

Gauge

Length

G(mm)

Smallest

Arc

Radius

R(mm)

Shortest

Area

A(mm)

Total

Length

L(mm)

Clamping

Area

Length

B(mm)

Clamping

Area

Diameter

C(mm)

Bar 125 02 625 01 gt10 gt75 ~ 145 ~ 35 20

Table 3-3 Specifications for Round Bar

33 Experiment Procedure

1 Attaching the Strain Gauge to the Tensile Specimen

(1) Prepare 1 ASTM E8 compliant tensile specimen round bar as shown in figure 3-7

(2) Prepare Strain Gauge as those described in table 3-4

(3) Prepare other consumables and adhesive agent such as epoxy adhesive or

cyanoacrylate adhesive as shown in figure 3-8

48

Fig 3-7 Actual Tensile Specimen

Fig 3-8 Other Materials Used (Such as Alcohol gauze transparent tape adhesive)

Gage Type

EA-06-120LZ-120E

Resistance in ohms at 24∘C

1200plusmn03

Gage Factor at 24∘C

2075plusmn05

Transverse Sensitivity at 24∘C

(+07plusmn02)

Table 3-4 Specifications for Strain Gauge

2 Attaching Strain Gauge

As shown in following figures we shall explain the attachment of the strain gauge

(1) Use sand paper and a rasp to clean thoroughly the surface where the strain gauge will be

attached to

49

(a)

(2) Use alcohol to wash the surface where the strain gauge will be attached and use gauze to rub

it off

(b)

(3) Find a clean surface and clean it with alcohol and gauze

(c)

(4) Place the strain gauge in the clean surface Use a piece of transparent tape on top of the strain

gauge after securely placed rip it off the surface carefully

50

(d)

(5) Use a piece of white paper to mark the place where the strain gauge will be attached and in

this way we can make sure that the strain gauge will be placed as horizontally and vertically

correct as possible

(e)

(6) In the place where we had our mark place the strain gauge

(f)

(7) Carefully lift one side of the tape and apply some of the adhesive agent to both the strain

gauge and specimenrsquos surface

(g)

51

(8) We need to make sure that the gauge and the specimen will be firmly attached so we gently

apply pressure with our thumb

(h)

(9) After the adhesive is fully dry we can carefully rip off the tape

(i)

(10) We need to do the whole process twice one for the horizontally placed strain gauge and one

for the vertically placed strain gauge

52

(j)

(11) We now proceed to solder the wires to the strain gauge

(k)

(12) After soldering we use a Volt Multimeter to measure that there is no contact between wires

If there is none then the specimen is ready for testing

(l)

(13) We now need to measure a 5cm distance and mark it to check and compare the elongation

before and after the tensile testing

(m)

53

Fig 3-9 Specimen-Strain Gauge Process

3 Tensile Test

(1) Enter the computer application that controls the tensile testing machine

(2) Turn on the tensile testing machine main switch

(3) Adjust the hydraulic pump to go back to its original position

(4) Bring the lowering motor down to a distance enough so as to attach the tensile specimen to the

system open the clamps and secure the specimen

(a)

(5) Connect all the necessary wires to the strain indicator equipment

54

(b)

(6) Start the ascending motor and wait for the expansion

(c)

Fig 3-10 Specimen-Tensile Testing Process

4 Start the Test

(1) Enter the software application and enter some variables needed for the experiment in the

specific screen

(2) Go back to the main screen and press the [測試] (measure) button to start the test and auto

recording in the software

(3) After the specimen breaks the mechanical device will automatically stop and ask the user to

enter the total displacement We take out the specimen from the testing machine and adjust the

machinersquos position back to its original position

(4) Save the results information

(5) Record the results from the strain indicator

34 Results

From this experiment we can get the Poissonrsquos Ratio Youngrsquos Modulus and Yield Strength etc and

because of the slippage phenomenon in the clamp at the moment of the test then the Elastic Limit will

display some yield phenomena So omit any undesirable results we just take the Yield portion of the

results as reference

In the process of the experiment the most important part to attend to is the attaching of the strain

gauge because the gaugersquos purpose is to measure the strain developed during the test and this strain

might be very small If the gaugersquos angle change during the test ie is not well attached this will affect

the accuracy of the measurements of Poissonrsquos ratio and Youngrsquos modulus

55

The materials provided by the manufacturer are SUM 23 and SUM 43 steel round bars and these two

types of materials have been through different heat treatment processes so they can be sub-divided

further into untreated material heat-treated material and black surface heat treated material for the two

materials with heat treatment the treatment process and finished are different In the end we only have

the mechanical properties that were calculated after our research of these materials

All of the specifications are identical to those shown in figure 3-6

341 SUM 23

Fig 3-11 SUM 23 Untreated Material

Number 7 10

Hardness(HRB) 74 75

Yield Stress (MPa) 448 440

Tensile Strength (MPa) 544 560

Poissonrsquos Ratio 029 027

Youngrsquos Modulus (GPa) 203 210

Cut-off Area Shrinking () 42 41

Elongation () 1125 1011

Table 3-5 Mechanical Properties of SUM 23 Untreated

56

Stress-Strain Diagram

(a)

(b)

57

Fig 3-12 Stress-Strain Diagrams for (a) 7 Round Bar and (b) 10 Round Bar

Cut-Off Area

(a)

(b)

Fig 3-13 Cut-Off Area of (a) 7 Round Bar and (b) 10 Round Bar

58

SUM 23 Nickel Round Bar

Fig 3-14 SUM 23 Nickel Material

Number 1 2 3 4

Hardness(HRB) 48 50 49 48

Yield Stress (MPa) 370 370 380 400

Tensile Strength (MPa) 455 451 450 450

Poissonrsquos Ratio 028 046 029 026

Youngrsquos Modulus (GPa) 243 303 246 206

Cut-off Area Shrinking () 803 803 726 601

Elongation () 566 65 602 647

Table 3-6 Mechanical Properties of SUM 23 Nickel

59

Stress-Strain Diagram

(a)

60

(b)

(c)

(d)

61

Fig 3-15 Stress-Strain Diagrams for (a) 1 Round Bar (b) 2 Round Bar (c) 3 Round Bar and (d)

4 Round Bar

Cut-Off Area

(a)

(b)

62

(c)

(d)

Fig 3-16 Cut-Off Area of (a) 1 Round Bar (b) 2 Round Bar (c) 3 Round Bar and (d) 4 Round

Bar

63

SUM 23 Black Surface Round Bar

Fig 3-17 SUM 23 Black Surface Material

Number 1 2 3

Hardness(HRB) 51 50 51

Yield Stress (MPa) 378 371 369

Tensile Strength (MPa) 467 465 464

Poissonrsquos Ratio 03 016 04

Youngrsquos Modulus (GPa) 215 266 266

Cut-off Area Shrinking () 986 94 848

Elongation () 748 805 761

Table 3-7 Mechanical Properties of SUM 23 Black Surface Material

64

Stress-Strain Diagram

(a)

(b)

65

(c)

Fig 3-18 Stress-Strain Diagrams for (a) 1 Round Bar 2 Round Bar and (c) 3 Round Bar

Cut-Off Surface

(a)

66

(b)

(c)

Fig 3-19 Cut-Off Surface of (a) 1 Round Bar 2 Round Bar and (c) 3 Round Bar

67

342 SUM 43

Fig 3-20 Untreated SUM 43 Untreated Material

Number 1 5

Hardness(HRB) 76 75

Yield Stress (MPa) 572 594

Tensile Strength (MPa) 743 785

Poissonrsquos Ratio 027 029

Youngrsquos Modulus (GPa) 200 202

Cut-off Area Shrinking () 338 2944

Elongation () 857 894

Table 3-8 Mechanical Properties of SUM 43 Untreated

68

Stress-Strain Diagrams

(a)

(b)

Fig 3-21 Stress-Strain Diagrams for SUM 43 (a) 1 Round Bar and (b) 5 Round Bar

69

Cut-Off Area

(a)

(b)

Fig 3-22 Cut-Off Area of SUM 43 (a) 1 Round Bar and (b) 5 Round Bar

70

SUM 43 Nickel Round Bar

Fig 3-23 SUM 43 Nickel Material

Number 4 5

Hardness(HRB) 51 50

Yield Stress (MPa) 1580 1544

Tensile Strength (MPa) 1639 1625

Poissonrsquos Ratio 03 028

Youngrsquos Modulus (GPa) 194 201

Cut-off Area Shrinking () 1697 137

Elongation () 376 265

Table 3-9 Mechanical Properties of SUM 43 Nickel

71

Stress-Strain Diagrams

(a)

(b)

Fig 3-24 Stress-Strain Diagrams for (a) 4 Round Bar and (b) 5 Round Bar

72

Cut-Off Area

(a)

(b)

Fig 3-25 Cut-Off Area of (a) 4 Round Bar and (b) 5 Round Bar

73

SUM 43 Black Surface Material

Fig 3-26 SUM 43 Black Surface Material

Number 3 5

Hardness(HRB) 56 56

Yield Stress (MPa) 1416 1361

Tensile Strength (MPa) 1591 1402

Poissonrsquos Ratio 029 031

Youngrsquos Modulus (GPa) 200 202

Cut-off Area Shrinking () 139 124

Elongation () 24 24

Table 3-10 Mechanical Properties of SUM 43 Black Surface Material

74

Stress-Strain Diagrams

0 2 4 6 8 10 12 14

-200

0

200

400

600

800

1000

1200

1400

1600

1800

應力 (MPa)

應變()

(a)

0 2 4 6 8 10

-200

0

200

400

600

800

1000

1200

1400

1600

應力

(MPa)

位移 ()

(b)

Fig 3-27 Stress-Strain Diagrams for (a) 3 Round Bar and (b) 5 Round Bar

(Note These curves were formulated using Visual Solutions Inc VisSim Software)

75

Cut-Off Area

(a)

(b)

Fig 3-28 Cut-Off Area of (a) 3 Round Bar and (b) 5 Round Bar

76

The force value (N) was retrieved from the Universal Testing Machine

The Poissonrsquos Ratio (ε) is calculated as

ε =

the values for the Poissonrsquos Ratio are in average around 0297

The Youngrsquos Modulus (E) is calculated as

E =

Where

Stress =

Cross-sectional Area =

where D is the Diameter

The value for D was in average around 1258 mm

The values shown by the computer because there is Slippage phenomena between the Clamp and the

specimen will not be taken into consideration for the elongation strain and Youngrsquos modulus and we will

refer to the values that we have meticulously calculated

77

Chapter 4 AR COATING IN DEPTH

41 Experimentrsquos Purpose and Principles

By means of a vacuum chamber and several other instruments we intend to apply Anti-Reflective

Coating using deposition process to a laser diode and in this way reduce its refraction so as to make it

lose less light in the process of amplification and we can control certain wavelengths we want produced

for certain desired applications in our case we are attempting to re-create a Bose-Einstein Condensate

An optimal BEC apparatus is shown in figure 4-1

Fig 4-1 BEC Apparatus

The main point of this experiment is to build a vacuum chamber system attach all the instrumentation

needed (Vacuum pump deposition meter and voltmeter) and use it to apply AR coating to a laser diode

After we have accomplished the AR coating other team will be in charge of designing the BEC apparatus

and use the results of our research

78

42 Experimentrsquos Equipment

421 Vacuum Chamber

For this research we designed a vacuum chamber whose main body is shown in figure 4-2 Its

dimensions are

Width 240 mm

Length 240 mm

Height 200 mm

Outer Diameter 4 in

Inner Diameter 15 in

Fig 4-2 Vacuum Chamber Main Body

The chamber is made up of 6 pass ways pass way A is the connection with the Laser Deposition

Equipment pass way B is the connection with the Turbo Pump and pass way C is for the connection with

the Deposition Source

A

C

B

79

Pass way C is for the deposition source as mentioned above This is a system where a thermal

resistance is heated by passing a high current through it which heats up a filament boat (made of tungsten)

where the material to be evaporated is place We control the temperature as such that the material will

evaporate and the heat will not cause the filament boat to crack

Because P = Isup2 R (where P is power I is current and R is resistance) to avoid the current to flow

where it is not desired we decided that the material for the Thermocouple shown in figure 4-3 should be

Copper ᴓ 63 mm We choose it that way because Copper has very good heat dissipation characteristics

and the resistance value is low It can reduce the value of the current enough to make the thermocouple to

create heat

Fig 4-3 Thermocouple

To the thermocouple we attach the tungsten filament boat We need to take notice of materials to be

used in this design because when using high current the tungsten filament boar will heat up and so the

material must be able to keep up with the heating potential of tungsten and has a low coefficient of heat

dissipation to avoid the tungsten to fail when heating up and therefore not evaporating Considering all

this we decide to use Stainless Steel

Because this clamp will be assembled inside the chamber after many revisions it was determined it

will have the shape shown in figure 4-4

Fig 4-4 Filament Boat Clamp Design

80

For the tungsten filament boat we bought the product from a distributor The dimensions are

Length 100 mm

Width 10 mm

Height 1 mm

Our thermocouple is 15 in but the pass way C is 4 in so we need to attach a Flange that connects

15in to 4in Because these specifications are quite difficult to achieve by Milling we had to use

electrical wire cutting

For the laser clamping system where the laser that is going to be AR coated will be placed will be

connected to pass way A the assembly is shown in figure 4-5 below

Fig 4-5 Cover Assembly

For this design we used an O-ring instead of a gasket so as to save time The design of the assembly

where the laser will be placed is shown in figure 4-6

Fig 4-6 Upper Cover Inner Assembly

D

E

F

81

Point D is the plate in the assembly where the laser diode will be fixed Because of the easy

processing we decide to use Aluminum and it is screwed to the top cover Point E is the connection for

the Quartz crystal resonator and it is designed in the same as point F in this way the results of the quartz

microbalance system will be more accurate in real time Point F is the final resting place for the laser

diode We use a Thor Labs Base with dimensions of ᴓ 9mm and ᴓ 56mm for two different size laser

diodes It just needs to be plugged in for easy installation

From figure 4-6 we know that the system needs signal system connections and because of the

change in temperature inside the chamber this could affect the functioning of the quartz microbalance so

we also need to install water tubes for cooling This is shown in figure 4-7 below

Fig 4-7 Diagram of Upper Cover Connections

In figure 4-8 we show the Feed through connections and their functions

Fig 4-8 Feed through Diagram

82

1 SQM-160 wire 5 Laser Connection 1 (Vin)

2 SQM-160 (G) 6 Laser Connection 2 (G)

3 K-Type-1 7 Laser Connection 3 (PD)

4 K-Type-2 8 Not In Use

The fully assembled chamber is shown in figure 4-9

Fig 4-9 Fully Assembled Chamber

422 Quartz Crystal Microbalance

For measuring the deposition on our target for coating we used the Inficon SQM-160 RateThickness

Monitor It is an easy to use instrument for measuring many types of thin-film coatings as shown in

figure 4-10

(a) Front Panel (b) Back Panel

Fig 4-10 Inficon SQM-160

83

Table 4-1 shows the technical specifications for this equipment

Number of sensors 2 Standard 4 additional optional

Sensor Frequency Range 40 MHz ~ 60 MHz

Reference Frequency Accuracy 002

Thickness Display Resolution 1 Aring

Thickness Resolution 015 Aring (Std) 0037 Aring (Hi Res)

Density of Stored Films 05-9999 gmcc

Tooling 10-399

Z-Factor 010-1000

Final Thickness 0000-9999k Aring

Measurement Period 15 to 2 sec

Simulation Mode Yes

Frequency Mode Yes

Rate Resolution 011 Arings

Dual Crystal Yes

Etch Mode Yes

Crystal Tooling 10-399

Crystal Fail Min Max 40 to 60 MHz 41 to 61 MHz

Power 100-120 200-240~plusmn10 nominal 20W

Operation Environment 0degC ~ 50degC

0 ~ 80 RH non-condensing

0 ~ 2000 meters

Class 1 Equipment

Pollution Degree 2

Rack Dimensions 885mm x 2127mm x 1969mm

Weight 27 kg

Table 4-1 Inficon SQM-160 RateThickness Monitor Specs

84

To the SQM-160 we need to connect an Oscillator We use the Sigma Instruments Remote Oscillator

Ser No 2 268 as shown in figure 4-11

Fig 4-11 Sigma Instruments Remote Oscillator

The connections diagram is shown in figure 4-12

Fig 4-12 SQM-160 Connections Diagram

85

423 Turbo Pump

For our experiments we used the Pfeiffer TCP 015 Electronic Drive Unit shown below in figure 4-13

Table 4-2 shows the technical specifications for this equipment

(a) Front Panel (b) Back Panel

Fig 4-13 Pfeiffer TCP 015 Electronic Drive

Connection Voltage (100V) 90-112

Mains Frequency 5060 Hz

Start-up Current 22 A

Nominal Frequency 1500 Hz

Rotation Speed 10V = 1500Hz plusmn2

Analog Output Current 10 V = 25 A plusmn 5

Rotation Speed Switchpoint 750 Hz

Works Setting 8 min

Permissible Ambient Temperature 0degC ~ 40degC

Dimensions Front Panel 1285mm x 1063mm

Insertion Length 227mm

Weight 27 Kg

Table 4-2 Pfeiffer TCP 015 Electronic Drive Specs

86

The connections diagram is shown in figure 4-14

Fig 4-14Connections Diagram for Pfeiffer TCP 015

To measure the pressure inside the chamber we use the Granville Phillips 375 Convectron Vacuum

Pressure Controller shown in figure 4-15

(a) Front Panel (b) Back Panel

Fig 4-15 Granville Phillips 375 Convectron

87

Its dimensions are shown in figure 4-16

Fig 4-16 Dimensions of Convectron

Table 4-3 shows the technical specifications for this equipment

Table 4-3 Granville Phillips 375 Convectron Vacuum Pressure Controller Specs

88

424 Multimeter

For our experiment we used the Keithley 2000 Digital Multimeter as shown in figure 4-17

(a) Front Panel (b) Back Panel

Fig 4-17 Keithley Model 2000 6-12-Digit Digital Multimeter

Its technical specifications are shown in table 4-4

Table 4-4 Keithley Model 2000 6-12-Digit Digital Multimeter Specs

89

43 Experiment Procedure

1 Connecting together the equipment and the chamber

(1) We first connect the resonator to the thickness monitor and connect the other side to the

chamber

(2) We now connect the flexible tubes to the turbo pump on one side and to the chamber on the

other

(3) We need to check that tubes are tightly connected to avoid any leaks in the vacuum pumping

process which will not allow us to get to our goal of Torr As shown in figure 4-18

(4) Connect the convectron to the system as shown in figure 4-19

Fig 4-18 checking for leaks using alcohol

Fig 4-19 Convectron attached to System

90

(5) Attach the clamps of the Multimeter to the bottom of the chamber as shown in figure 4-20

(6) Place the Quartz crystal in place

(7) Close tight vacuum chamber

(8) Connect all electrical appliances to power source

Fig 4-20 Multimeter Connections

2 Starting up the System

(1) We turn on all the devices as such Check all systems are ready to function Reset all values

that might be left over from previous tests

(2) Start the thickness monitor and set all values for this experiment In our case we got to testing

the system but not actual coating So we used the simulation mode of the thickness monitor as

shown in figure 4-21

Fig 4-21 Simulation Mode

91

(3) Start the turbo pump Make sure the lid on the vacuum chamber is tightly closed

(4) Start convectron and record initial pressure

(5) Start Multimeter and record initial current

3 Coating Process

(1) If we have the deposition material inside the filament boat the power source for the high

current must be started as well

(2) Record all initial values for thickness current pressure

(3) For an ideal experiment we need a thickness of around 101 nm a pressure of Torr and

a current of 300 A

44 Results

From previous experiments we have shown that we can turn a LED into a laser by means of AR

Coating In figure 4-22 shown below we can compare the actual results of a Diode before and after AR

coating From the blue line we can see that when the diode is at a current of 15mA its light will change

from LED to laser and if we look at the red line its critical current is around 30 to 35 mA

Fig 4-22 AR Coating Comparison for Laser Diodes

This means that the light emitted is not as strong as if the diode had been coated because inside the

chamber there must be some excitation first so the reflectivity of both sides inside the diode must be high

So because of the coating in one of the sides we have opened a door and let the light come out so the

critical current is risen as such and will be higher value than that of before the coating

92

In the following figures we can see the difference between before and after coating in a material The

thickness is around 1016 nm for this material

Fig 4-23 Before Coating

Fig 4-24 After Coating

93

Chapter 5 CONCLUSIONS AND RECOMMENDATIONS

51 Conclusions

For the first part of this independent study taking into consideration the data that came out of our

research and that sent by the provider we can say

1 SUM 23 after heat treatment will unexpectedly develop cracking in the middle of the tensile

testing process and suddenly break

2 Itrsquos possible that in the process of heat treatment to the SUM 23 material the treatment was not

uniform and this will create a pre-loaded moment force on one side that pushes on the other side

of the specimen resulting in material deformation

3 In the process of attaching the strain gauges to the materials it is very easy to make errors due to

poor adhesion or sudden removal in the tensile testing process

For our second part of the independent study the following can be made

1 At the beginning of this independent study we had no idea what Bose-Einstein Condensate was

or what was its purpose After much literature we finally comprehended the basic principles to

put into practice for our research

2 Our systemrsquos basic working principles and equipmentrsquos complexity are a little difficult to grasp

but hopefully we were able to understand enough of it

3 Theoretically from relation between the power and current we can know the advantages and

disadvantages of AR Coating

4 We were able to assemble the system and run test on its functions Even though we were able to

do this there is still much more work left to do with this system

52 Recommendations

For the Tensile Testing the following can be said

1 Ask the provider to check on the process of heat treatment on the SUM 23 material and give

them the information we have gathered through our test so they can correct for the mechanical

properties found if any change is needed

2 To avoid the problem of the inaccuracy of the poor adhesion of strain gauges we can attach

multiple strain gauges to the same one specimen so as to correlate data and improve our results

For the AR Coating the following can be said

1 We need to make sure that there are no physical defects on the main body of the chamber so as to

achieve maximum efficiency in the vacuum process If there was then the vacuum will arrive to

certain point and then start to decrease

2 It would be preferable to add some sort of visual aid that will allow the user to check the inside of

the chamber without actually opening it This will help us determine at what times we should

manipulate the current to better evaporate the substrate

94

REFERENCES

[1] A L Window Strain Gauge Technology Elsevier Applied Science London and New York 2nd

Edition 1992

[2] CC Perry and HR Lissner Strain Gauge Primer McGraw-Hill Book Co Inc New York 1955

[3] James W Dally William F Riley McGraw-Hill 1978

[4] University of Colorado Boulder BEC - What is it and where did the idea come from

httpwwwcoloradoeduphysics2000becwhat_is_ithtml

[5] Ultraslow Light amp Bose-Einstein Condensates Two-way Control with Coherent Light amp Atom

Fields Harvard Hau Lab Dr Lene Vestergaard Hau Optics amp Photonics News 16 1995

[6] The Art of Taming Light Ultra-slow and Stopped Light Harvard Hau Lab Dr Lene

Vestergaard Hau Europhysics News 2004

[7] Nonlinear Optics Shocking Superfluids Harvard Hau Lab Dr Lene Vestergaard Hau Nature

Physics 2007

[8] Model P3 Strain Indicator and Recorder Instruction Manual Vishay Micro-Measurements 2005

[9] Granville-Phillips Series 375 Convectron Vacuum Gauge Controller Instruction Manual Brooks

Automation 2008

[10] Effect of Film Thickness on the Validity of the Sauerbrey Equation for Hydrated Polyelectrolyte

Films Vogt Lin Wu White 2004

[11] Quartz Crystal Microbalance Study of DNA Immobilization and Hybridization for DNA Sensor

Development Chang Zhao 2008

[12] Installation of Strain Gages with SR-4 PrecoatAdhesive Vishay Micro-Measurements 2005

[13] Strain Gauge Measurement ndash A Tutorial National Instruments 1998

[14] Correlation between Vickers Hardness Number and Yield Stress of Cold-Formed Products

Yavuz Tekkaya

[15] httpsenwikipediaorg

Page 41: PC Hinge Materials Testing and AR Laser Diode Coating

41

Chapter 3 TENSILE TESTING IN DEPTH

31 Experimentrsquos Purpose and Principles

By means of Universal testing machine and Strain gauges we were able to observe discuss and

analyze the phenomena created when a specimen of certain material is manipulated under an external load

and determine the stress strain and deformation values later we can use the graphing methods of

stress-strain diagram to describe it

The main point of this experiment is that after the tensile specimen is tested use computer analysis

and the actual strain data and after statistical adjustment make the final results report (Tensile testing

experiment is in accordance with ASTM E8)

32 Experimentrsquos Equipment

321 Universal Testing Machine

For the materials testing experiment part of this research we use a Universal Testing Machine as

shown in figure 31 The maximum load it can apply is 100 Ton After the test specimen is secured on the

device with the use of instrumentation the load exerted and the effects of this become apparent on the

specimen and even the smallest of changes can be recorded For our research we used the Chun Yen

Testing Machines Co Ltd 100 Ton Micro Computer Universal Tensile Tester

Fig 31 Universal Testing Machine

42

Table 31 shows the specifications for this machine

Max Capacity 100 Ton

Accuracy plusmn1

Tension (mm) Max Space 1150mm

Grip for Rod 20-70mm

Ram Stroke 250mm

Effective Column Interval 940mm

Crosshead Speed 300mmmin

Testing Speed 0-50mmmin

Volume of Machine 1700times1000times3350mm(LtimesWtimesH)

Volume of Control Panel 1000times800times1500mm(LtimesWtimesH)

Weight 8000kg

Power 3∮220V 20A

Computer AMD K6-2-350

OS Windows XP

Screen 15rdquo CRT

Table 3-1 Chun Yen Testing Machine Specs Table

The connections diagram is shown in figure 3-2

Fig 3-2 Diagram for System Connections

43

When the test specimen is placed when the external force is applied the Load Cell can measure the

size of the applied force and the Encoder measures the expansion rate of change The Local Controller

receives all the information from the 2 units after arranging the results they are displayed in the

computer and they can be afterwards submitted for more complex analysis such as Finite Element

Analysis and we can get the Stress-Strain Diagram

322 Strain Measurement Equipment

The equipment used in our research provides a four-channel measurement that means we can use up

to 4 strain gauges at a time to do our measurements and provides 3 different bridge arrangements as

shown in figure 3-3

(a) (b) (c)

Fig 3-3 Input Connections for Strain Indicator

Figure 3-3 (a) is the Quarter Bridge (b) is the Half Bridge and (c) is the Full Bridge and Transducers

For our study we used the Quarter Bridge and use the Strain Gauge values to decide the position of the

connecting wires The Strain indicator is shown in figure 3-4

Fig 3-4 Vishay Micro-Measurements Model P3 Strain Indicator and Recorder

44

Input Connections Tool Free eccentric lever release

4-channel input

Wire diameter16-28AWG

Bridge Configurations Quarter- Half- and Full Bridge

Bridge Impedance 60-2000Ω

Display 128 64 pixel FSTN positive gray LCD

Data Conversion AD Converter filter

Measurement Range Resolution Strain Range plusmn155mVV

Resolution plusmn00005mVV

Measurement Accuracy plusmn01 of reading plusmn3 counts

Gage Factor Control 0500-9900

Balance Control Software either manual or automatic

Bridge Excitation 15VDC nominal

Communication Interface USB Cable Included

Data Storage Removable Media Card

Shunt Calibration Across bridge completion resistors controlled

by software When Gage Factor=200

120Ω350Ω1000Ω

Analog Output Value 0 to 25V max

Ranges plusmn320 microε plusmn3200 microε plusmn32000 microε

Error 05 output voltage +5mV

Max Error 14 output voltage + 20mV

Update rate 480 samplessec

Output Load 2000Ω

Power Battery Two Alkaline D cells

Battery life 400 hours typ

USB 5V 100mA

Operational Environment Temperature 0-50

Humidity Up to 90 Non-condensing

Case Aluminum Alloy

Size and Weight 228times152times152(mm) 20(kg)

Table 3-2 Vishay Micro-Measurements Model P3 Strain Indicator and Recorder Specs

45

323 Strain Gauge

The strain gaugersquos main basic principle is to use a resistancersquos characteristics to measure the strain

The inside connections of the strain indicator are shown in figure 3-5

Fig 3-5 Inner Connections

As shown above this is a quarter-bridge connection We connect equal-length 3 wires to the 2

connections allowed by the strain gauge wire 1 and 3 can be used to cancel out the effects of temperature

to the resistance and because of the addition of wires 1 and 3 wire 2 can directly measure the experiment

results from the strain gauge and therefore the strain developed with no influence of temperature

If there were no two measuring leads then the relations will be

R 4 =R g +2R L

Where Rg is the Strain Gauge Value and RL is the wire resistance then

4

4

R

R=

Lg

g

RR

R

2

=

gL

gg

RR

RR

21

amp

4

4

R

R=

g

g

R

R(1- L)

Where L is the Signal Loss Factor and so

L =gL

gL

RR

RR

21

2

g

L

R

2R if

g

L

R

2Rltlt1

46

(Actual Value R g =120R L =08g

L

R

2Ris always much smaller than 1)

R 4 =R g +2R LR 2 =R 3 =rR gR 1 =R g 32 RR =0

V 0 =V 2)1( r

r

(

4

4

R

R-

1

1

R

R)

The first term describes loss attenuation effects second term describes loss of balancing capabilities

effects

V 0 =V 2)1( r

r

[

)2

(Lg

g

RR

R

+

T

Lg

g

RR

R

)

2( + T

Lg

L

RR

R

)

2

2( -(

g

g

R

R) T ]

The first term describes loss attenuation effects and loss of balancing capabilities effects the second

third and fourth terms describe the temperature effects on the wire

For the three-wire method we have

L =gL

gL

RR

RR

1

g

L

R

R if

g

L

R

Rltlt1

V 0 =V 2)1( r

r

[

)(Lg

g

RR

R

+

T

Lg

g

RR

R

)( + T

Lg

L

RR

R

)

2( -

T

Lg

g

RR

R

)( - T

Lg

L

RR

R

)

2( ]

V 0 = V2)1( r

r

)(

Lg

g

RR

R

In the last four terms inside parenthesis we can see the effects of temperature being cancelled out and the

effect on first term is not great so this is the reason why in our research we use three wires

47

324 Specimen Measurements

The tensile specimens used in this research are compliant of ASTM E8 Tensile parameters as shown

in figure 3-6

Fig 3-6 Tensile Specimen

Diameter

D(mm)

Gauge

Length

G(mm)

Smallest

Arc

Radius

R(mm)

Shortest

Area

A(mm)

Total

Length

L(mm)

Clamping

Area

Length

B(mm)

Clamping

Area

Diameter

C(mm)

Bar 125 02 625 01 gt10 gt75 ~ 145 ~ 35 20

Table 3-3 Specifications for Round Bar

33 Experiment Procedure

1 Attaching the Strain Gauge to the Tensile Specimen

(1) Prepare 1 ASTM E8 compliant tensile specimen round bar as shown in figure 3-7

(2) Prepare Strain Gauge as those described in table 3-4

(3) Prepare other consumables and adhesive agent such as epoxy adhesive or

cyanoacrylate adhesive as shown in figure 3-8

48

Fig 3-7 Actual Tensile Specimen

Fig 3-8 Other Materials Used (Such as Alcohol gauze transparent tape adhesive)

Gage Type

EA-06-120LZ-120E

Resistance in ohms at 24∘C

1200plusmn03

Gage Factor at 24∘C

2075plusmn05

Transverse Sensitivity at 24∘C

(+07plusmn02)

Table 3-4 Specifications for Strain Gauge

2 Attaching Strain Gauge

As shown in following figures we shall explain the attachment of the strain gauge

(1) Use sand paper and a rasp to clean thoroughly the surface where the strain gauge will be

attached to

49

(a)

(2) Use alcohol to wash the surface where the strain gauge will be attached and use gauze to rub

it off

(b)

(3) Find a clean surface and clean it with alcohol and gauze

(c)

(4) Place the strain gauge in the clean surface Use a piece of transparent tape on top of the strain

gauge after securely placed rip it off the surface carefully

50

(d)

(5) Use a piece of white paper to mark the place where the strain gauge will be attached and in

this way we can make sure that the strain gauge will be placed as horizontally and vertically

correct as possible

(e)

(6) In the place where we had our mark place the strain gauge

(f)

(7) Carefully lift one side of the tape and apply some of the adhesive agent to both the strain

gauge and specimenrsquos surface

(g)

51

(8) We need to make sure that the gauge and the specimen will be firmly attached so we gently

apply pressure with our thumb

(h)

(9) After the adhesive is fully dry we can carefully rip off the tape

(i)

(10) We need to do the whole process twice one for the horizontally placed strain gauge and one

for the vertically placed strain gauge

52

(j)

(11) We now proceed to solder the wires to the strain gauge

(k)

(12) After soldering we use a Volt Multimeter to measure that there is no contact between wires

If there is none then the specimen is ready for testing

(l)

(13) We now need to measure a 5cm distance and mark it to check and compare the elongation

before and after the tensile testing

(m)

53

Fig 3-9 Specimen-Strain Gauge Process

3 Tensile Test

(1) Enter the computer application that controls the tensile testing machine

(2) Turn on the tensile testing machine main switch

(3) Adjust the hydraulic pump to go back to its original position

(4) Bring the lowering motor down to a distance enough so as to attach the tensile specimen to the

system open the clamps and secure the specimen

(a)

(5) Connect all the necessary wires to the strain indicator equipment

54

(b)

(6) Start the ascending motor and wait for the expansion

(c)

Fig 3-10 Specimen-Tensile Testing Process

4 Start the Test

(1) Enter the software application and enter some variables needed for the experiment in the

specific screen

(2) Go back to the main screen and press the [測試] (measure) button to start the test and auto

recording in the software

(3) After the specimen breaks the mechanical device will automatically stop and ask the user to

enter the total displacement We take out the specimen from the testing machine and adjust the

machinersquos position back to its original position

(4) Save the results information

(5) Record the results from the strain indicator

34 Results

From this experiment we can get the Poissonrsquos Ratio Youngrsquos Modulus and Yield Strength etc and

because of the slippage phenomenon in the clamp at the moment of the test then the Elastic Limit will

display some yield phenomena So omit any undesirable results we just take the Yield portion of the

results as reference

In the process of the experiment the most important part to attend to is the attaching of the strain

gauge because the gaugersquos purpose is to measure the strain developed during the test and this strain

might be very small If the gaugersquos angle change during the test ie is not well attached this will affect

the accuracy of the measurements of Poissonrsquos ratio and Youngrsquos modulus

55

The materials provided by the manufacturer are SUM 23 and SUM 43 steel round bars and these two

types of materials have been through different heat treatment processes so they can be sub-divided

further into untreated material heat-treated material and black surface heat treated material for the two

materials with heat treatment the treatment process and finished are different In the end we only have

the mechanical properties that were calculated after our research of these materials

All of the specifications are identical to those shown in figure 3-6

341 SUM 23

Fig 3-11 SUM 23 Untreated Material

Number 7 10

Hardness(HRB) 74 75

Yield Stress (MPa) 448 440

Tensile Strength (MPa) 544 560

Poissonrsquos Ratio 029 027

Youngrsquos Modulus (GPa) 203 210

Cut-off Area Shrinking () 42 41

Elongation () 1125 1011

Table 3-5 Mechanical Properties of SUM 23 Untreated

56

Stress-Strain Diagram

(a)

(b)

57

Fig 3-12 Stress-Strain Diagrams for (a) 7 Round Bar and (b) 10 Round Bar

Cut-Off Area

(a)

(b)

Fig 3-13 Cut-Off Area of (a) 7 Round Bar and (b) 10 Round Bar

58

SUM 23 Nickel Round Bar

Fig 3-14 SUM 23 Nickel Material

Number 1 2 3 4

Hardness(HRB) 48 50 49 48

Yield Stress (MPa) 370 370 380 400

Tensile Strength (MPa) 455 451 450 450

Poissonrsquos Ratio 028 046 029 026

Youngrsquos Modulus (GPa) 243 303 246 206

Cut-off Area Shrinking () 803 803 726 601

Elongation () 566 65 602 647

Table 3-6 Mechanical Properties of SUM 23 Nickel

59

Stress-Strain Diagram

(a)

60

(b)

(c)

(d)

61

Fig 3-15 Stress-Strain Diagrams for (a) 1 Round Bar (b) 2 Round Bar (c) 3 Round Bar and (d)

4 Round Bar

Cut-Off Area

(a)

(b)

62

(c)

(d)

Fig 3-16 Cut-Off Area of (a) 1 Round Bar (b) 2 Round Bar (c) 3 Round Bar and (d) 4 Round

Bar

63

SUM 23 Black Surface Round Bar

Fig 3-17 SUM 23 Black Surface Material

Number 1 2 3

Hardness(HRB) 51 50 51

Yield Stress (MPa) 378 371 369

Tensile Strength (MPa) 467 465 464

Poissonrsquos Ratio 03 016 04

Youngrsquos Modulus (GPa) 215 266 266

Cut-off Area Shrinking () 986 94 848

Elongation () 748 805 761

Table 3-7 Mechanical Properties of SUM 23 Black Surface Material

64

Stress-Strain Diagram

(a)

(b)

65

(c)

Fig 3-18 Stress-Strain Diagrams for (a) 1 Round Bar 2 Round Bar and (c) 3 Round Bar

Cut-Off Surface

(a)

66

(b)

(c)

Fig 3-19 Cut-Off Surface of (a) 1 Round Bar 2 Round Bar and (c) 3 Round Bar

67

342 SUM 43

Fig 3-20 Untreated SUM 43 Untreated Material

Number 1 5

Hardness(HRB) 76 75

Yield Stress (MPa) 572 594

Tensile Strength (MPa) 743 785

Poissonrsquos Ratio 027 029

Youngrsquos Modulus (GPa) 200 202

Cut-off Area Shrinking () 338 2944

Elongation () 857 894

Table 3-8 Mechanical Properties of SUM 43 Untreated

68

Stress-Strain Diagrams

(a)

(b)

Fig 3-21 Stress-Strain Diagrams for SUM 43 (a) 1 Round Bar and (b) 5 Round Bar

69

Cut-Off Area

(a)

(b)

Fig 3-22 Cut-Off Area of SUM 43 (a) 1 Round Bar and (b) 5 Round Bar

70

SUM 43 Nickel Round Bar

Fig 3-23 SUM 43 Nickel Material

Number 4 5

Hardness(HRB) 51 50

Yield Stress (MPa) 1580 1544

Tensile Strength (MPa) 1639 1625

Poissonrsquos Ratio 03 028

Youngrsquos Modulus (GPa) 194 201

Cut-off Area Shrinking () 1697 137

Elongation () 376 265

Table 3-9 Mechanical Properties of SUM 43 Nickel

71

Stress-Strain Diagrams

(a)

(b)

Fig 3-24 Stress-Strain Diagrams for (a) 4 Round Bar and (b) 5 Round Bar

72

Cut-Off Area

(a)

(b)

Fig 3-25 Cut-Off Area of (a) 4 Round Bar and (b) 5 Round Bar

73

SUM 43 Black Surface Material

Fig 3-26 SUM 43 Black Surface Material

Number 3 5

Hardness(HRB) 56 56

Yield Stress (MPa) 1416 1361

Tensile Strength (MPa) 1591 1402

Poissonrsquos Ratio 029 031

Youngrsquos Modulus (GPa) 200 202

Cut-off Area Shrinking () 139 124

Elongation () 24 24

Table 3-10 Mechanical Properties of SUM 43 Black Surface Material

74

Stress-Strain Diagrams

0 2 4 6 8 10 12 14

-200

0

200

400

600

800

1000

1200

1400

1600

1800

應力 (MPa)

應變()

(a)

0 2 4 6 8 10

-200

0

200

400

600

800

1000

1200

1400

1600

應力

(MPa)

位移 ()

(b)

Fig 3-27 Stress-Strain Diagrams for (a) 3 Round Bar and (b) 5 Round Bar

(Note These curves were formulated using Visual Solutions Inc VisSim Software)

75

Cut-Off Area

(a)

(b)

Fig 3-28 Cut-Off Area of (a) 3 Round Bar and (b) 5 Round Bar

76

The force value (N) was retrieved from the Universal Testing Machine

The Poissonrsquos Ratio (ε) is calculated as

ε =

the values for the Poissonrsquos Ratio are in average around 0297

The Youngrsquos Modulus (E) is calculated as

E =

Where

Stress =

Cross-sectional Area =

where D is the Diameter

The value for D was in average around 1258 mm

The values shown by the computer because there is Slippage phenomena between the Clamp and the

specimen will not be taken into consideration for the elongation strain and Youngrsquos modulus and we will

refer to the values that we have meticulously calculated

77

Chapter 4 AR COATING IN DEPTH

41 Experimentrsquos Purpose and Principles

By means of a vacuum chamber and several other instruments we intend to apply Anti-Reflective

Coating using deposition process to a laser diode and in this way reduce its refraction so as to make it

lose less light in the process of amplification and we can control certain wavelengths we want produced

for certain desired applications in our case we are attempting to re-create a Bose-Einstein Condensate

An optimal BEC apparatus is shown in figure 4-1

Fig 4-1 BEC Apparatus

The main point of this experiment is to build a vacuum chamber system attach all the instrumentation

needed (Vacuum pump deposition meter and voltmeter) and use it to apply AR coating to a laser diode

After we have accomplished the AR coating other team will be in charge of designing the BEC apparatus

and use the results of our research

78

42 Experimentrsquos Equipment

421 Vacuum Chamber

For this research we designed a vacuum chamber whose main body is shown in figure 4-2 Its

dimensions are

Width 240 mm

Length 240 mm

Height 200 mm

Outer Diameter 4 in

Inner Diameter 15 in

Fig 4-2 Vacuum Chamber Main Body

The chamber is made up of 6 pass ways pass way A is the connection with the Laser Deposition

Equipment pass way B is the connection with the Turbo Pump and pass way C is for the connection with

the Deposition Source

A

C

B

79

Pass way C is for the deposition source as mentioned above This is a system where a thermal

resistance is heated by passing a high current through it which heats up a filament boat (made of tungsten)

where the material to be evaporated is place We control the temperature as such that the material will

evaporate and the heat will not cause the filament boat to crack

Because P = Isup2 R (where P is power I is current and R is resistance) to avoid the current to flow

where it is not desired we decided that the material for the Thermocouple shown in figure 4-3 should be

Copper ᴓ 63 mm We choose it that way because Copper has very good heat dissipation characteristics

and the resistance value is low It can reduce the value of the current enough to make the thermocouple to

create heat

Fig 4-3 Thermocouple

To the thermocouple we attach the tungsten filament boat We need to take notice of materials to be

used in this design because when using high current the tungsten filament boar will heat up and so the

material must be able to keep up with the heating potential of tungsten and has a low coefficient of heat

dissipation to avoid the tungsten to fail when heating up and therefore not evaporating Considering all

this we decide to use Stainless Steel

Because this clamp will be assembled inside the chamber after many revisions it was determined it

will have the shape shown in figure 4-4

Fig 4-4 Filament Boat Clamp Design

80

For the tungsten filament boat we bought the product from a distributor The dimensions are

Length 100 mm

Width 10 mm

Height 1 mm

Our thermocouple is 15 in but the pass way C is 4 in so we need to attach a Flange that connects

15in to 4in Because these specifications are quite difficult to achieve by Milling we had to use

electrical wire cutting

For the laser clamping system where the laser that is going to be AR coated will be placed will be

connected to pass way A the assembly is shown in figure 4-5 below

Fig 4-5 Cover Assembly

For this design we used an O-ring instead of a gasket so as to save time The design of the assembly

where the laser will be placed is shown in figure 4-6

Fig 4-6 Upper Cover Inner Assembly

D

E

F

81

Point D is the plate in the assembly where the laser diode will be fixed Because of the easy

processing we decide to use Aluminum and it is screwed to the top cover Point E is the connection for

the Quartz crystal resonator and it is designed in the same as point F in this way the results of the quartz

microbalance system will be more accurate in real time Point F is the final resting place for the laser

diode We use a Thor Labs Base with dimensions of ᴓ 9mm and ᴓ 56mm for two different size laser

diodes It just needs to be plugged in for easy installation

From figure 4-6 we know that the system needs signal system connections and because of the

change in temperature inside the chamber this could affect the functioning of the quartz microbalance so

we also need to install water tubes for cooling This is shown in figure 4-7 below

Fig 4-7 Diagram of Upper Cover Connections

In figure 4-8 we show the Feed through connections and their functions

Fig 4-8 Feed through Diagram

82

1 SQM-160 wire 5 Laser Connection 1 (Vin)

2 SQM-160 (G) 6 Laser Connection 2 (G)

3 K-Type-1 7 Laser Connection 3 (PD)

4 K-Type-2 8 Not In Use

The fully assembled chamber is shown in figure 4-9

Fig 4-9 Fully Assembled Chamber

422 Quartz Crystal Microbalance

For measuring the deposition on our target for coating we used the Inficon SQM-160 RateThickness

Monitor It is an easy to use instrument for measuring many types of thin-film coatings as shown in

figure 4-10

(a) Front Panel (b) Back Panel

Fig 4-10 Inficon SQM-160

83

Table 4-1 shows the technical specifications for this equipment

Number of sensors 2 Standard 4 additional optional

Sensor Frequency Range 40 MHz ~ 60 MHz

Reference Frequency Accuracy 002

Thickness Display Resolution 1 Aring

Thickness Resolution 015 Aring (Std) 0037 Aring (Hi Res)

Density of Stored Films 05-9999 gmcc

Tooling 10-399

Z-Factor 010-1000

Final Thickness 0000-9999k Aring

Measurement Period 15 to 2 sec

Simulation Mode Yes

Frequency Mode Yes

Rate Resolution 011 Arings

Dual Crystal Yes

Etch Mode Yes

Crystal Tooling 10-399

Crystal Fail Min Max 40 to 60 MHz 41 to 61 MHz

Power 100-120 200-240~plusmn10 nominal 20W

Operation Environment 0degC ~ 50degC

0 ~ 80 RH non-condensing

0 ~ 2000 meters

Class 1 Equipment

Pollution Degree 2

Rack Dimensions 885mm x 2127mm x 1969mm

Weight 27 kg

Table 4-1 Inficon SQM-160 RateThickness Monitor Specs

84

To the SQM-160 we need to connect an Oscillator We use the Sigma Instruments Remote Oscillator

Ser No 2 268 as shown in figure 4-11

Fig 4-11 Sigma Instruments Remote Oscillator

The connections diagram is shown in figure 4-12

Fig 4-12 SQM-160 Connections Diagram

85

423 Turbo Pump

For our experiments we used the Pfeiffer TCP 015 Electronic Drive Unit shown below in figure 4-13

Table 4-2 shows the technical specifications for this equipment

(a) Front Panel (b) Back Panel

Fig 4-13 Pfeiffer TCP 015 Electronic Drive

Connection Voltage (100V) 90-112

Mains Frequency 5060 Hz

Start-up Current 22 A

Nominal Frequency 1500 Hz

Rotation Speed 10V = 1500Hz plusmn2

Analog Output Current 10 V = 25 A plusmn 5

Rotation Speed Switchpoint 750 Hz

Works Setting 8 min

Permissible Ambient Temperature 0degC ~ 40degC

Dimensions Front Panel 1285mm x 1063mm

Insertion Length 227mm

Weight 27 Kg

Table 4-2 Pfeiffer TCP 015 Electronic Drive Specs

86

The connections diagram is shown in figure 4-14

Fig 4-14Connections Diagram for Pfeiffer TCP 015

To measure the pressure inside the chamber we use the Granville Phillips 375 Convectron Vacuum

Pressure Controller shown in figure 4-15

(a) Front Panel (b) Back Panel

Fig 4-15 Granville Phillips 375 Convectron

87

Its dimensions are shown in figure 4-16

Fig 4-16 Dimensions of Convectron

Table 4-3 shows the technical specifications for this equipment

Table 4-3 Granville Phillips 375 Convectron Vacuum Pressure Controller Specs

88

424 Multimeter

For our experiment we used the Keithley 2000 Digital Multimeter as shown in figure 4-17

(a) Front Panel (b) Back Panel

Fig 4-17 Keithley Model 2000 6-12-Digit Digital Multimeter

Its technical specifications are shown in table 4-4

Table 4-4 Keithley Model 2000 6-12-Digit Digital Multimeter Specs

89

43 Experiment Procedure

1 Connecting together the equipment and the chamber

(1) We first connect the resonator to the thickness monitor and connect the other side to the

chamber

(2) We now connect the flexible tubes to the turbo pump on one side and to the chamber on the

other

(3) We need to check that tubes are tightly connected to avoid any leaks in the vacuum pumping

process which will not allow us to get to our goal of Torr As shown in figure 4-18

(4) Connect the convectron to the system as shown in figure 4-19

Fig 4-18 checking for leaks using alcohol

Fig 4-19 Convectron attached to System

90

(5) Attach the clamps of the Multimeter to the bottom of the chamber as shown in figure 4-20

(6) Place the Quartz crystal in place

(7) Close tight vacuum chamber

(8) Connect all electrical appliances to power source

Fig 4-20 Multimeter Connections

2 Starting up the System

(1) We turn on all the devices as such Check all systems are ready to function Reset all values

that might be left over from previous tests

(2) Start the thickness monitor and set all values for this experiment In our case we got to testing

the system but not actual coating So we used the simulation mode of the thickness monitor as

shown in figure 4-21

Fig 4-21 Simulation Mode

91

(3) Start the turbo pump Make sure the lid on the vacuum chamber is tightly closed

(4) Start convectron and record initial pressure

(5) Start Multimeter and record initial current

3 Coating Process

(1) If we have the deposition material inside the filament boat the power source for the high

current must be started as well

(2) Record all initial values for thickness current pressure

(3) For an ideal experiment we need a thickness of around 101 nm a pressure of Torr and

a current of 300 A

44 Results

From previous experiments we have shown that we can turn a LED into a laser by means of AR

Coating In figure 4-22 shown below we can compare the actual results of a Diode before and after AR

coating From the blue line we can see that when the diode is at a current of 15mA its light will change

from LED to laser and if we look at the red line its critical current is around 30 to 35 mA

Fig 4-22 AR Coating Comparison for Laser Diodes

This means that the light emitted is not as strong as if the diode had been coated because inside the

chamber there must be some excitation first so the reflectivity of both sides inside the diode must be high

So because of the coating in one of the sides we have opened a door and let the light come out so the

critical current is risen as such and will be higher value than that of before the coating

92

In the following figures we can see the difference between before and after coating in a material The

thickness is around 1016 nm for this material

Fig 4-23 Before Coating

Fig 4-24 After Coating

93

Chapter 5 CONCLUSIONS AND RECOMMENDATIONS

51 Conclusions

For the first part of this independent study taking into consideration the data that came out of our

research and that sent by the provider we can say

1 SUM 23 after heat treatment will unexpectedly develop cracking in the middle of the tensile

testing process and suddenly break

2 Itrsquos possible that in the process of heat treatment to the SUM 23 material the treatment was not

uniform and this will create a pre-loaded moment force on one side that pushes on the other side

of the specimen resulting in material deformation

3 In the process of attaching the strain gauges to the materials it is very easy to make errors due to

poor adhesion or sudden removal in the tensile testing process

For our second part of the independent study the following can be made

1 At the beginning of this independent study we had no idea what Bose-Einstein Condensate was

or what was its purpose After much literature we finally comprehended the basic principles to

put into practice for our research

2 Our systemrsquos basic working principles and equipmentrsquos complexity are a little difficult to grasp

but hopefully we were able to understand enough of it

3 Theoretically from relation between the power and current we can know the advantages and

disadvantages of AR Coating

4 We were able to assemble the system and run test on its functions Even though we were able to

do this there is still much more work left to do with this system

52 Recommendations

For the Tensile Testing the following can be said

1 Ask the provider to check on the process of heat treatment on the SUM 23 material and give

them the information we have gathered through our test so they can correct for the mechanical

properties found if any change is needed

2 To avoid the problem of the inaccuracy of the poor adhesion of strain gauges we can attach

multiple strain gauges to the same one specimen so as to correlate data and improve our results

For the AR Coating the following can be said

1 We need to make sure that there are no physical defects on the main body of the chamber so as to

achieve maximum efficiency in the vacuum process If there was then the vacuum will arrive to

certain point and then start to decrease

2 It would be preferable to add some sort of visual aid that will allow the user to check the inside of

the chamber without actually opening it This will help us determine at what times we should

manipulate the current to better evaporate the substrate

94

REFERENCES

[1] A L Window Strain Gauge Technology Elsevier Applied Science London and New York 2nd

Edition 1992

[2] CC Perry and HR Lissner Strain Gauge Primer McGraw-Hill Book Co Inc New York 1955

[3] James W Dally William F Riley McGraw-Hill 1978

[4] University of Colorado Boulder BEC - What is it and where did the idea come from

httpwwwcoloradoeduphysics2000becwhat_is_ithtml

[5] Ultraslow Light amp Bose-Einstein Condensates Two-way Control with Coherent Light amp Atom

Fields Harvard Hau Lab Dr Lene Vestergaard Hau Optics amp Photonics News 16 1995

[6] The Art of Taming Light Ultra-slow and Stopped Light Harvard Hau Lab Dr Lene

Vestergaard Hau Europhysics News 2004

[7] Nonlinear Optics Shocking Superfluids Harvard Hau Lab Dr Lene Vestergaard Hau Nature

Physics 2007

[8] Model P3 Strain Indicator and Recorder Instruction Manual Vishay Micro-Measurements 2005

[9] Granville-Phillips Series 375 Convectron Vacuum Gauge Controller Instruction Manual Brooks

Automation 2008

[10] Effect of Film Thickness on the Validity of the Sauerbrey Equation for Hydrated Polyelectrolyte

Films Vogt Lin Wu White 2004

[11] Quartz Crystal Microbalance Study of DNA Immobilization and Hybridization for DNA Sensor

Development Chang Zhao 2008

[12] Installation of Strain Gages with SR-4 PrecoatAdhesive Vishay Micro-Measurements 2005

[13] Strain Gauge Measurement ndash A Tutorial National Instruments 1998

[14] Correlation between Vickers Hardness Number and Yield Stress of Cold-Formed Products

Yavuz Tekkaya

[15] httpsenwikipediaorg

Page 42: PC Hinge Materials Testing and AR Laser Diode Coating

42

Table 31 shows the specifications for this machine

Max Capacity 100 Ton

Accuracy plusmn1

Tension (mm) Max Space 1150mm

Grip for Rod 20-70mm

Ram Stroke 250mm

Effective Column Interval 940mm

Crosshead Speed 300mmmin

Testing Speed 0-50mmmin

Volume of Machine 1700times1000times3350mm(LtimesWtimesH)

Volume of Control Panel 1000times800times1500mm(LtimesWtimesH)

Weight 8000kg

Power 3∮220V 20A

Computer AMD K6-2-350

OS Windows XP

Screen 15rdquo CRT

Table 3-1 Chun Yen Testing Machine Specs Table

The connections diagram is shown in figure 3-2

Fig 3-2 Diagram for System Connections

43

When the test specimen is placed when the external force is applied the Load Cell can measure the

size of the applied force and the Encoder measures the expansion rate of change The Local Controller

receives all the information from the 2 units after arranging the results they are displayed in the

computer and they can be afterwards submitted for more complex analysis such as Finite Element

Analysis and we can get the Stress-Strain Diagram

322 Strain Measurement Equipment

The equipment used in our research provides a four-channel measurement that means we can use up

to 4 strain gauges at a time to do our measurements and provides 3 different bridge arrangements as

shown in figure 3-3

(a) (b) (c)

Fig 3-3 Input Connections for Strain Indicator

Figure 3-3 (a) is the Quarter Bridge (b) is the Half Bridge and (c) is the Full Bridge and Transducers

For our study we used the Quarter Bridge and use the Strain Gauge values to decide the position of the

connecting wires The Strain indicator is shown in figure 3-4

Fig 3-4 Vishay Micro-Measurements Model P3 Strain Indicator and Recorder

44

Input Connections Tool Free eccentric lever release

4-channel input

Wire diameter16-28AWG

Bridge Configurations Quarter- Half- and Full Bridge

Bridge Impedance 60-2000Ω

Display 128 64 pixel FSTN positive gray LCD

Data Conversion AD Converter filter

Measurement Range Resolution Strain Range plusmn155mVV

Resolution plusmn00005mVV

Measurement Accuracy plusmn01 of reading plusmn3 counts

Gage Factor Control 0500-9900

Balance Control Software either manual or automatic

Bridge Excitation 15VDC nominal

Communication Interface USB Cable Included

Data Storage Removable Media Card

Shunt Calibration Across bridge completion resistors controlled

by software When Gage Factor=200

120Ω350Ω1000Ω

Analog Output Value 0 to 25V max

Ranges plusmn320 microε plusmn3200 microε plusmn32000 microε

Error 05 output voltage +5mV

Max Error 14 output voltage + 20mV

Update rate 480 samplessec

Output Load 2000Ω

Power Battery Two Alkaline D cells

Battery life 400 hours typ

USB 5V 100mA

Operational Environment Temperature 0-50

Humidity Up to 90 Non-condensing

Case Aluminum Alloy

Size and Weight 228times152times152(mm) 20(kg)

Table 3-2 Vishay Micro-Measurements Model P3 Strain Indicator and Recorder Specs

45

323 Strain Gauge

The strain gaugersquos main basic principle is to use a resistancersquos characteristics to measure the strain

The inside connections of the strain indicator are shown in figure 3-5

Fig 3-5 Inner Connections

As shown above this is a quarter-bridge connection We connect equal-length 3 wires to the 2

connections allowed by the strain gauge wire 1 and 3 can be used to cancel out the effects of temperature

to the resistance and because of the addition of wires 1 and 3 wire 2 can directly measure the experiment

results from the strain gauge and therefore the strain developed with no influence of temperature

If there were no two measuring leads then the relations will be

R 4 =R g +2R L

Where Rg is the Strain Gauge Value and RL is the wire resistance then

4

4

R

R=

Lg

g

RR

R

2

=

gL

gg

RR

RR

21

amp

4

4

R

R=

g

g

R

R(1- L)

Where L is the Signal Loss Factor and so

L =gL

gL

RR

RR

21

2

g

L

R

2R if

g

L

R

2Rltlt1

46

(Actual Value R g =120R L =08g

L

R

2Ris always much smaller than 1)

R 4 =R g +2R LR 2 =R 3 =rR gR 1 =R g 32 RR =0

V 0 =V 2)1( r

r

(

4

4

R

R-

1

1

R

R)

The first term describes loss attenuation effects second term describes loss of balancing capabilities

effects

V 0 =V 2)1( r

r

[

)2

(Lg

g

RR

R

+

T

Lg

g

RR

R

)

2( + T

Lg

L

RR

R

)

2

2( -(

g

g

R

R) T ]

The first term describes loss attenuation effects and loss of balancing capabilities effects the second

third and fourth terms describe the temperature effects on the wire

For the three-wire method we have

L =gL

gL

RR

RR

1

g

L

R

R if

g

L

R

Rltlt1

V 0 =V 2)1( r

r

[

)(Lg

g

RR

R

+

T

Lg

g

RR

R

)( + T

Lg

L

RR

R

)

2( -

T

Lg

g

RR

R

)( - T

Lg

L

RR

R

)

2( ]

V 0 = V2)1( r

r

)(

Lg

g

RR

R

In the last four terms inside parenthesis we can see the effects of temperature being cancelled out and the

effect on first term is not great so this is the reason why in our research we use three wires

47

324 Specimen Measurements

The tensile specimens used in this research are compliant of ASTM E8 Tensile parameters as shown

in figure 3-6

Fig 3-6 Tensile Specimen

Diameter

D(mm)

Gauge

Length

G(mm)

Smallest

Arc

Radius

R(mm)

Shortest

Area

A(mm)

Total

Length

L(mm)

Clamping

Area

Length

B(mm)

Clamping

Area

Diameter

C(mm)

Bar 125 02 625 01 gt10 gt75 ~ 145 ~ 35 20

Table 3-3 Specifications for Round Bar

33 Experiment Procedure

1 Attaching the Strain Gauge to the Tensile Specimen

(1) Prepare 1 ASTM E8 compliant tensile specimen round bar as shown in figure 3-7

(2) Prepare Strain Gauge as those described in table 3-4

(3) Prepare other consumables and adhesive agent such as epoxy adhesive or

cyanoacrylate adhesive as shown in figure 3-8

48

Fig 3-7 Actual Tensile Specimen

Fig 3-8 Other Materials Used (Such as Alcohol gauze transparent tape adhesive)

Gage Type

EA-06-120LZ-120E

Resistance in ohms at 24∘C

1200plusmn03

Gage Factor at 24∘C

2075plusmn05

Transverse Sensitivity at 24∘C

(+07plusmn02)

Table 3-4 Specifications for Strain Gauge

2 Attaching Strain Gauge

As shown in following figures we shall explain the attachment of the strain gauge

(1) Use sand paper and a rasp to clean thoroughly the surface where the strain gauge will be

attached to

49

(a)

(2) Use alcohol to wash the surface where the strain gauge will be attached and use gauze to rub

it off

(b)

(3) Find a clean surface and clean it with alcohol and gauze

(c)

(4) Place the strain gauge in the clean surface Use a piece of transparent tape on top of the strain

gauge after securely placed rip it off the surface carefully

50

(d)

(5) Use a piece of white paper to mark the place where the strain gauge will be attached and in

this way we can make sure that the strain gauge will be placed as horizontally and vertically

correct as possible

(e)

(6) In the place where we had our mark place the strain gauge

(f)

(7) Carefully lift one side of the tape and apply some of the adhesive agent to both the strain

gauge and specimenrsquos surface

(g)

51

(8) We need to make sure that the gauge and the specimen will be firmly attached so we gently

apply pressure with our thumb

(h)

(9) After the adhesive is fully dry we can carefully rip off the tape

(i)

(10) We need to do the whole process twice one for the horizontally placed strain gauge and one

for the vertically placed strain gauge

52

(j)

(11) We now proceed to solder the wires to the strain gauge

(k)

(12) After soldering we use a Volt Multimeter to measure that there is no contact between wires

If there is none then the specimen is ready for testing

(l)

(13) We now need to measure a 5cm distance and mark it to check and compare the elongation

before and after the tensile testing

(m)

53

Fig 3-9 Specimen-Strain Gauge Process

3 Tensile Test

(1) Enter the computer application that controls the tensile testing machine

(2) Turn on the tensile testing machine main switch

(3) Adjust the hydraulic pump to go back to its original position

(4) Bring the lowering motor down to a distance enough so as to attach the tensile specimen to the

system open the clamps and secure the specimen

(a)

(5) Connect all the necessary wires to the strain indicator equipment

54

(b)

(6) Start the ascending motor and wait for the expansion

(c)

Fig 3-10 Specimen-Tensile Testing Process

4 Start the Test

(1) Enter the software application and enter some variables needed for the experiment in the

specific screen

(2) Go back to the main screen and press the [測試] (measure) button to start the test and auto

recording in the software

(3) After the specimen breaks the mechanical device will automatically stop and ask the user to

enter the total displacement We take out the specimen from the testing machine and adjust the

machinersquos position back to its original position

(4) Save the results information

(5) Record the results from the strain indicator

34 Results

From this experiment we can get the Poissonrsquos Ratio Youngrsquos Modulus and Yield Strength etc and

because of the slippage phenomenon in the clamp at the moment of the test then the Elastic Limit will

display some yield phenomena So omit any undesirable results we just take the Yield portion of the

results as reference

In the process of the experiment the most important part to attend to is the attaching of the strain

gauge because the gaugersquos purpose is to measure the strain developed during the test and this strain

might be very small If the gaugersquos angle change during the test ie is not well attached this will affect

the accuracy of the measurements of Poissonrsquos ratio and Youngrsquos modulus

55

The materials provided by the manufacturer are SUM 23 and SUM 43 steel round bars and these two

types of materials have been through different heat treatment processes so they can be sub-divided

further into untreated material heat-treated material and black surface heat treated material for the two

materials with heat treatment the treatment process and finished are different In the end we only have

the mechanical properties that were calculated after our research of these materials

All of the specifications are identical to those shown in figure 3-6

341 SUM 23

Fig 3-11 SUM 23 Untreated Material

Number 7 10

Hardness(HRB) 74 75

Yield Stress (MPa) 448 440

Tensile Strength (MPa) 544 560

Poissonrsquos Ratio 029 027

Youngrsquos Modulus (GPa) 203 210

Cut-off Area Shrinking () 42 41

Elongation () 1125 1011

Table 3-5 Mechanical Properties of SUM 23 Untreated

56

Stress-Strain Diagram

(a)

(b)

57

Fig 3-12 Stress-Strain Diagrams for (a) 7 Round Bar and (b) 10 Round Bar

Cut-Off Area

(a)

(b)

Fig 3-13 Cut-Off Area of (a) 7 Round Bar and (b) 10 Round Bar

58

SUM 23 Nickel Round Bar

Fig 3-14 SUM 23 Nickel Material

Number 1 2 3 4

Hardness(HRB) 48 50 49 48

Yield Stress (MPa) 370 370 380 400

Tensile Strength (MPa) 455 451 450 450

Poissonrsquos Ratio 028 046 029 026

Youngrsquos Modulus (GPa) 243 303 246 206

Cut-off Area Shrinking () 803 803 726 601

Elongation () 566 65 602 647

Table 3-6 Mechanical Properties of SUM 23 Nickel

59

Stress-Strain Diagram

(a)

60

(b)

(c)

(d)

61

Fig 3-15 Stress-Strain Diagrams for (a) 1 Round Bar (b) 2 Round Bar (c) 3 Round Bar and (d)

4 Round Bar

Cut-Off Area

(a)

(b)

62

(c)

(d)

Fig 3-16 Cut-Off Area of (a) 1 Round Bar (b) 2 Round Bar (c) 3 Round Bar and (d) 4 Round

Bar

63

SUM 23 Black Surface Round Bar

Fig 3-17 SUM 23 Black Surface Material

Number 1 2 3

Hardness(HRB) 51 50 51

Yield Stress (MPa) 378 371 369

Tensile Strength (MPa) 467 465 464

Poissonrsquos Ratio 03 016 04

Youngrsquos Modulus (GPa) 215 266 266

Cut-off Area Shrinking () 986 94 848

Elongation () 748 805 761

Table 3-7 Mechanical Properties of SUM 23 Black Surface Material

64

Stress-Strain Diagram

(a)

(b)

65

(c)

Fig 3-18 Stress-Strain Diagrams for (a) 1 Round Bar 2 Round Bar and (c) 3 Round Bar

Cut-Off Surface

(a)

66

(b)

(c)

Fig 3-19 Cut-Off Surface of (a) 1 Round Bar 2 Round Bar and (c) 3 Round Bar

67

342 SUM 43

Fig 3-20 Untreated SUM 43 Untreated Material

Number 1 5

Hardness(HRB) 76 75

Yield Stress (MPa) 572 594

Tensile Strength (MPa) 743 785

Poissonrsquos Ratio 027 029

Youngrsquos Modulus (GPa) 200 202

Cut-off Area Shrinking () 338 2944

Elongation () 857 894

Table 3-8 Mechanical Properties of SUM 43 Untreated

68

Stress-Strain Diagrams

(a)

(b)

Fig 3-21 Stress-Strain Diagrams for SUM 43 (a) 1 Round Bar and (b) 5 Round Bar

69

Cut-Off Area

(a)

(b)

Fig 3-22 Cut-Off Area of SUM 43 (a) 1 Round Bar and (b) 5 Round Bar

70

SUM 43 Nickel Round Bar

Fig 3-23 SUM 43 Nickel Material

Number 4 5

Hardness(HRB) 51 50

Yield Stress (MPa) 1580 1544

Tensile Strength (MPa) 1639 1625

Poissonrsquos Ratio 03 028

Youngrsquos Modulus (GPa) 194 201

Cut-off Area Shrinking () 1697 137

Elongation () 376 265

Table 3-9 Mechanical Properties of SUM 43 Nickel

71

Stress-Strain Diagrams

(a)

(b)

Fig 3-24 Stress-Strain Diagrams for (a) 4 Round Bar and (b) 5 Round Bar

72

Cut-Off Area

(a)

(b)

Fig 3-25 Cut-Off Area of (a) 4 Round Bar and (b) 5 Round Bar

73

SUM 43 Black Surface Material

Fig 3-26 SUM 43 Black Surface Material

Number 3 5

Hardness(HRB) 56 56

Yield Stress (MPa) 1416 1361

Tensile Strength (MPa) 1591 1402

Poissonrsquos Ratio 029 031

Youngrsquos Modulus (GPa) 200 202

Cut-off Area Shrinking () 139 124

Elongation () 24 24

Table 3-10 Mechanical Properties of SUM 43 Black Surface Material

74

Stress-Strain Diagrams

0 2 4 6 8 10 12 14

-200

0

200

400

600

800

1000

1200

1400

1600

1800

應力 (MPa)

應變()

(a)

0 2 4 6 8 10

-200

0

200

400

600

800

1000

1200

1400

1600

應力

(MPa)

位移 ()

(b)

Fig 3-27 Stress-Strain Diagrams for (a) 3 Round Bar and (b) 5 Round Bar

(Note These curves were formulated using Visual Solutions Inc VisSim Software)

75

Cut-Off Area

(a)

(b)

Fig 3-28 Cut-Off Area of (a) 3 Round Bar and (b) 5 Round Bar

76

The force value (N) was retrieved from the Universal Testing Machine

The Poissonrsquos Ratio (ε) is calculated as

ε =

the values for the Poissonrsquos Ratio are in average around 0297

The Youngrsquos Modulus (E) is calculated as

E =

Where

Stress =

Cross-sectional Area =

where D is the Diameter

The value for D was in average around 1258 mm

The values shown by the computer because there is Slippage phenomena between the Clamp and the

specimen will not be taken into consideration for the elongation strain and Youngrsquos modulus and we will

refer to the values that we have meticulously calculated

77

Chapter 4 AR COATING IN DEPTH

41 Experimentrsquos Purpose and Principles

By means of a vacuum chamber and several other instruments we intend to apply Anti-Reflective

Coating using deposition process to a laser diode and in this way reduce its refraction so as to make it

lose less light in the process of amplification and we can control certain wavelengths we want produced

for certain desired applications in our case we are attempting to re-create a Bose-Einstein Condensate

An optimal BEC apparatus is shown in figure 4-1

Fig 4-1 BEC Apparatus

The main point of this experiment is to build a vacuum chamber system attach all the instrumentation

needed (Vacuum pump deposition meter and voltmeter) and use it to apply AR coating to a laser diode

After we have accomplished the AR coating other team will be in charge of designing the BEC apparatus

and use the results of our research

78

42 Experimentrsquos Equipment

421 Vacuum Chamber

For this research we designed a vacuum chamber whose main body is shown in figure 4-2 Its

dimensions are

Width 240 mm

Length 240 mm

Height 200 mm

Outer Diameter 4 in

Inner Diameter 15 in

Fig 4-2 Vacuum Chamber Main Body

The chamber is made up of 6 pass ways pass way A is the connection with the Laser Deposition

Equipment pass way B is the connection with the Turbo Pump and pass way C is for the connection with

the Deposition Source

A

C

B

79

Pass way C is for the deposition source as mentioned above This is a system where a thermal

resistance is heated by passing a high current through it which heats up a filament boat (made of tungsten)

where the material to be evaporated is place We control the temperature as such that the material will

evaporate and the heat will not cause the filament boat to crack

Because P = Isup2 R (where P is power I is current and R is resistance) to avoid the current to flow

where it is not desired we decided that the material for the Thermocouple shown in figure 4-3 should be

Copper ᴓ 63 mm We choose it that way because Copper has very good heat dissipation characteristics

and the resistance value is low It can reduce the value of the current enough to make the thermocouple to

create heat

Fig 4-3 Thermocouple

To the thermocouple we attach the tungsten filament boat We need to take notice of materials to be

used in this design because when using high current the tungsten filament boar will heat up and so the

material must be able to keep up with the heating potential of tungsten and has a low coefficient of heat

dissipation to avoid the tungsten to fail when heating up and therefore not evaporating Considering all

this we decide to use Stainless Steel

Because this clamp will be assembled inside the chamber after many revisions it was determined it

will have the shape shown in figure 4-4

Fig 4-4 Filament Boat Clamp Design

80

For the tungsten filament boat we bought the product from a distributor The dimensions are

Length 100 mm

Width 10 mm

Height 1 mm

Our thermocouple is 15 in but the pass way C is 4 in so we need to attach a Flange that connects

15in to 4in Because these specifications are quite difficult to achieve by Milling we had to use

electrical wire cutting

For the laser clamping system where the laser that is going to be AR coated will be placed will be

connected to pass way A the assembly is shown in figure 4-5 below

Fig 4-5 Cover Assembly

For this design we used an O-ring instead of a gasket so as to save time The design of the assembly

where the laser will be placed is shown in figure 4-6

Fig 4-6 Upper Cover Inner Assembly

D

E

F

81

Point D is the plate in the assembly where the laser diode will be fixed Because of the easy

processing we decide to use Aluminum and it is screwed to the top cover Point E is the connection for

the Quartz crystal resonator and it is designed in the same as point F in this way the results of the quartz

microbalance system will be more accurate in real time Point F is the final resting place for the laser

diode We use a Thor Labs Base with dimensions of ᴓ 9mm and ᴓ 56mm for two different size laser

diodes It just needs to be plugged in for easy installation

From figure 4-6 we know that the system needs signal system connections and because of the

change in temperature inside the chamber this could affect the functioning of the quartz microbalance so

we also need to install water tubes for cooling This is shown in figure 4-7 below

Fig 4-7 Diagram of Upper Cover Connections

In figure 4-8 we show the Feed through connections and their functions

Fig 4-8 Feed through Diagram

82

1 SQM-160 wire 5 Laser Connection 1 (Vin)

2 SQM-160 (G) 6 Laser Connection 2 (G)

3 K-Type-1 7 Laser Connection 3 (PD)

4 K-Type-2 8 Not In Use

The fully assembled chamber is shown in figure 4-9

Fig 4-9 Fully Assembled Chamber

422 Quartz Crystal Microbalance

For measuring the deposition on our target for coating we used the Inficon SQM-160 RateThickness

Monitor It is an easy to use instrument for measuring many types of thin-film coatings as shown in

figure 4-10

(a) Front Panel (b) Back Panel

Fig 4-10 Inficon SQM-160

83

Table 4-1 shows the technical specifications for this equipment

Number of sensors 2 Standard 4 additional optional

Sensor Frequency Range 40 MHz ~ 60 MHz

Reference Frequency Accuracy 002

Thickness Display Resolution 1 Aring

Thickness Resolution 015 Aring (Std) 0037 Aring (Hi Res)

Density of Stored Films 05-9999 gmcc

Tooling 10-399

Z-Factor 010-1000

Final Thickness 0000-9999k Aring

Measurement Period 15 to 2 sec

Simulation Mode Yes

Frequency Mode Yes

Rate Resolution 011 Arings

Dual Crystal Yes

Etch Mode Yes

Crystal Tooling 10-399

Crystal Fail Min Max 40 to 60 MHz 41 to 61 MHz

Power 100-120 200-240~plusmn10 nominal 20W

Operation Environment 0degC ~ 50degC

0 ~ 80 RH non-condensing

0 ~ 2000 meters

Class 1 Equipment

Pollution Degree 2

Rack Dimensions 885mm x 2127mm x 1969mm

Weight 27 kg

Table 4-1 Inficon SQM-160 RateThickness Monitor Specs

84

To the SQM-160 we need to connect an Oscillator We use the Sigma Instruments Remote Oscillator

Ser No 2 268 as shown in figure 4-11

Fig 4-11 Sigma Instruments Remote Oscillator

The connections diagram is shown in figure 4-12

Fig 4-12 SQM-160 Connections Diagram

85

423 Turbo Pump

For our experiments we used the Pfeiffer TCP 015 Electronic Drive Unit shown below in figure 4-13

Table 4-2 shows the technical specifications for this equipment

(a) Front Panel (b) Back Panel

Fig 4-13 Pfeiffer TCP 015 Electronic Drive

Connection Voltage (100V) 90-112

Mains Frequency 5060 Hz

Start-up Current 22 A

Nominal Frequency 1500 Hz

Rotation Speed 10V = 1500Hz plusmn2

Analog Output Current 10 V = 25 A plusmn 5

Rotation Speed Switchpoint 750 Hz

Works Setting 8 min

Permissible Ambient Temperature 0degC ~ 40degC

Dimensions Front Panel 1285mm x 1063mm

Insertion Length 227mm

Weight 27 Kg

Table 4-2 Pfeiffer TCP 015 Electronic Drive Specs

86

The connections diagram is shown in figure 4-14

Fig 4-14Connections Diagram for Pfeiffer TCP 015

To measure the pressure inside the chamber we use the Granville Phillips 375 Convectron Vacuum

Pressure Controller shown in figure 4-15

(a) Front Panel (b) Back Panel

Fig 4-15 Granville Phillips 375 Convectron

87

Its dimensions are shown in figure 4-16

Fig 4-16 Dimensions of Convectron

Table 4-3 shows the technical specifications for this equipment

Table 4-3 Granville Phillips 375 Convectron Vacuum Pressure Controller Specs

88

424 Multimeter

For our experiment we used the Keithley 2000 Digital Multimeter as shown in figure 4-17

(a) Front Panel (b) Back Panel

Fig 4-17 Keithley Model 2000 6-12-Digit Digital Multimeter

Its technical specifications are shown in table 4-4

Table 4-4 Keithley Model 2000 6-12-Digit Digital Multimeter Specs

89

43 Experiment Procedure

1 Connecting together the equipment and the chamber

(1) We first connect the resonator to the thickness monitor and connect the other side to the

chamber

(2) We now connect the flexible tubes to the turbo pump on one side and to the chamber on the

other

(3) We need to check that tubes are tightly connected to avoid any leaks in the vacuum pumping

process which will not allow us to get to our goal of Torr As shown in figure 4-18

(4) Connect the convectron to the system as shown in figure 4-19

Fig 4-18 checking for leaks using alcohol

Fig 4-19 Convectron attached to System

90

(5) Attach the clamps of the Multimeter to the bottom of the chamber as shown in figure 4-20

(6) Place the Quartz crystal in place

(7) Close tight vacuum chamber

(8) Connect all electrical appliances to power source

Fig 4-20 Multimeter Connections

2 Starting up the System

(1) We turn on all the devices as such Check all systems are ready to function Reset all values

that might be left over from previous tests

(2) Start the thickness monitor and set all values for this experiment In our case we got to testing

the system but not actual coating So we used the simulation mode of the thickness monitor as

shown in figure 4-21

Fig 4-21 Simulation Mode

91

(3) Start the turbo pump Make sure the lid on the vacuum chamber is tightly closed

(4) Start convectron and record initial pressure

(5) Start Multimeter and record initial current

3 Coating Process

(1) If we have the deposition material inside the filament boat the power source for the high

current must be started as well

(2) Record all initial values for thickness current pressure

(3) For an ideal experiment we need a thickness of around 101 nm a pressure of Torr and

a current of 300 A

44 Results

From previous experiments we have shown that we can turn a LED into a laser by means of AR

Coating In figure 4-22 shown below we can compare the actual results of a Diode before and after AR

coating From the blue line we can see that when the diode is at a current of 15mA its light will change

from LED to laser and if we look at the red line its critical current is around 30 to 35 mA

Fig 4-22 AR Coating Comparison for Laser Diodes

This means that the light emitted is not as strong as if the diode had been coated because inside the

chamber there must be some excitation first so the reflectivity of both sides inside the diode must be high

So because of the coating in one of the sides we have opened a door and let the light come out so the

critical current is risen as such and will be higher value than that of before the coating

92

In the following figures we can see the difference between before and after coating in a material The

thickness is around 1016 nm for this material

Fig 4-23 Before Coating

Fig 4-24 After Coating

93

Chapter 5 CONCLUSIONS AND RECOMMENDATIONS

51 Conclusions

For the first part of this independent study taking into consideration the data that came out of our

research and that sent by the provider we can say

1 SUM 23 after heat treatment will unexpectedly develop cracking in the middle of the tensile

testing process and suddenly break

2 Itrsquos possible that in the process of heat treatment to the SUM 23 material the treatment was not

uniform and this will create a pre-loaded moment force on one side that pushes on the other side

of the specimen resulting in material deformation

3 In the process of attaching the strain gauges to the materials it is very easy to make errors due to

poor adhesion or sudden removal in the tensile testing process

For our second part of the independent study the following can be made

1 At the beginning of this independent study we had no idea what Bose-Einstein Condensate was

or what was its purpose After much literature we finally comprehended the basic principles to

put into practice for our research

2 Our systemrsquos basic working principles and equipmentrsquos complexity are a little difficult to grasp

but hopefully we were able to understand enough of it

3 Theoretically from relation between the power and current we can know the advantages and

disadvantages of AR Coating

4 We were able to assemble the system and run test on its functions Even though we were able to

do this there is still much more work left to do with this system

52 Recommendations

For the Tensile Testing the following can be said

1 Ask the provider to check on the process of heat treatment on the SUM 23 material and give

them the information we have gathered through our test so they can correct for the mechanical

properties found if any change is needed

2 To avoid the problem of the inaccuracy of the poor adhesion of strain gauges we can attach

multiple strain gauges to the same one specimen so as to correlate data and improve our results

For the AR Coating the following can be said

1 We need to make sure that there are no physical defects on the main body of the chamber so as to

achieve maximum efficiency in the vacuum process If there was then the vacuum will arrive to

certain point and then start to decrease

2 It would be preferable to add some sort of visual aid that will allow the user to check the inside of

the chamber without actually opening it This will help us determine at what times we should

manipulate the current to better evaporate the substrate

94

REFERENCES

[1] A L Window Strain Gauge Technology Elsevier Applied Science London and New York 2nd

Edition 1992

[2] CC Perry and HR Lissner Strain Gauge Primer McGraw-Hill Book Co Inc New York 1955

[3] James W Dally William F Riley McGraw-Hill 1978

[4] University of Colorado Boulder BEC - What is it and where did the idea come from

httpwwwcoloradoeduphysics2000becwhat_is_ithtml

[5] Ultraslow Light amp Bose-Einstein Condensates Two-way Control with Coherent Light amp Atom

Fields Harvard Hau Lab Dr Lene Vestergaard Hau Optics amp Photonics News 16 1995

[6] The Art of Taming Light Ultra-slow and Stopped Light Harvard Hau Lab Dr Lene

Vestergaard Hau Europhysics News 2004

[7] Nonlinear Optics Shocking Superfluids Harvard Hau Lab Dr Lene Vestergaard Hau Nature

Physics 2007

[8] Model P3 Strain Indicator and Recorder Instruction Manual Vishay Micro-Measurements 2005

[9] Granville-Phillips Series 375 Convectron Vacuum Gauge Controller Instruction Manual Brooks

Automation 2008

[10] Effect of Film Thickness on the Validity of the Sauerbrey Equation for Hydrated Polyelectrolyte

Films Vogt Lin Wu White 2004

[11] Quartz Crystal Microbalance Study of DNA Immobilization and Hybridization for DNA Sensor

Development Chang Zhao 2008

[12] Installation of Strain Gages with SR-4 PrecoatAdhesive Vishay Micro-Measurements 2005

[13] Strain Gauge Measurement ndash A Tutorial National Instruments 1998

[14] Correlation between Vickers Hardness Number and Yield Stress of Cold-Formed Products

Yavuz Tekkaya

[15] httpsenwikipediaorg

Page 43: PC Hinge Materials Testing and AR Laser Diode Coating

43

When the test specimen is placed when the external force is applied the Load Cell can measure the

size of the applied force and the Encoder measures the expansion rate of change The Local Controller

receives all the information from the 2 units after arranging the results they are displayed in the

computer and they can be afterwards submitted for more complex analysis such as Finite Element

Analysis and we can get the Stress-Strain Diagram

322 Strain Measurement Equipment

The equipment used in our research provides a four-channel measurement that means we can use up

to 4 strain gauges at a time to do our measurements and provides 3 different bridge arrangements as

shown in figure 3-3

(a) (b) (c)

Fig 3-3 Input Connections for Strain Indicator

Figure 3-3 (a) is the Quarter Bridge (b) is the Half Bridge and (c) is the Full Bridge and Transducers

For our study we used the Quarter Bridge and use the Strain Gauge values to decide the position of the

connecting wires The Strain indicator is shown in figure 3-4

Fig 3-4 Vishay Micro-Measurements Model P3 Strain Indicator and Recorder

44

Input Connections Tool Free eccentric lever release

4-channel input

Wire diameter16-28AWG

Bridge Configurations Quarter- Half- and Full Bridge

Bridge Impedance 60-2000Ω

Display 128 64 pixel FSTN positive gray LCD

Data Conversion AD Converter filter

Measurement Range Resolution Strain Range plusmn155mVV

Resolution plusmn00005mVV

Measurement Accuracy plusmn01 of reading plusmn3 counts

Gage Factor Control 0500-9900

Balance Control Software either manual or automatic

Bridge Excitation 15VDC nominal

Communication Interface USB Cable Included

Data Storage Removable Media Card

Shunt Calibration Across bridge completion resistors controlled

by software When Gage Factor=200

120Ω350Ω1000Ω

Analog Output Value 0 to 25V max

Ranges plusmn320 microε plusmn3200 microε plusmn32000 microε

Error 05 output voltage +5mV

Max Error 14 output voltage + 20mV

Update rate 480 samplessec

Output Load 2000Ω

Power Battery Two Alkaline D cells

Battery life 400 hours typ

USB 5V 100mA

Operational Environment Temperature 0-50

Humidity Up to 90 Non-condensing

Case Aluminum Alloy

Size and Weight 228times152times152(mm) 20(kg)

Table 3-2 Vishay Micro-Measurements Model P3 Strain Indicator and Recorder Specs

45

323 Strain Gauge

The strain gaugersquos main basic principle is to use a resistancersquos characteristics to measure the strain

The inside connections of the strain indicator are shown in figure 3-5

Fig 3-5 Inner Connections

As shown above this is a quarter-bridge connection We connect equal-length 3 wires to the 2

connections allowed by the strain gauge wire 1 and 3 can be used to cancel out the effects of temperature

to the resistance and because of the addition of wires 1 and 3 wire 2 can directly measure the experiment

results from the strain gauge and therefore the strain developed with no influence of temperature

If there were no two measuring leads then the relations will be

R 4 =R g +2R L

Where Rg is the Strain Gauge Value and RL is the wire resistance then

4

4

R

R=

Lg

g

RR

R

2

=

gL

gg

RR

RR

21

amp

4

4

R

R=

g

g

R

R(1- L)

Where L is the Signal Loss Factor and so

L =gL

gL

RR

RR

21

2

g

L

R

2R if

g

L

R

2Rltlt1

46

(Actual Value R g =120R L =08g

L

R

2Ris always much smaller than 1)

R 4 =R g +2R LR 2 =R 3 =rR gR 1 =R g 32 RR =0

V 0 =V 2)1( r

r

(

4

4

R

R-

1

1

R

R)

The first term describes loss attenuation effects second term describes loss of balancing capabilities

effects

V 0 =V 2)1( r

r

[

)2

(Lg

g

RR

R

+

T

Lg

g

RR

R

)

2( + T

Lg

L

RR

R

)

2

2( -(

g

g

R

R) T ]

The first term describes loss attenuation effects and loss of balancing capabilities effects the second

third and fourth terms describe the temperature effects on the wire

For the three-wire method we have

L =gL

gL

RR

RR

1

g

L

R

R if

g

L

R

Rltlt1

V 0 =V 2)1( r

r

[

)(Lg

g

RR

R

+

T

Lg

g

RR

R

)( + T

Lg

L

RR

R

)

2( -

T

Lg

g

RR

R

)( - T

Lg

L

RR

R

)

2( ]

V 0 = V2)1( r

r

)(

Lg

g

RR

R

In the last four terms inside parenthesis we can see the effects of temperature being cancelled out and the

effect on first term is not great so this is the reason why in our research we use three wires

47

324 Specimen Measurements

The tensile specimens used in this research are compliant of ASTM E8 Tensile parameters as shown

in figure 3-6

Fig 3-6 Tensile Specimen

Diameter

D(mm)

Gauge

Length

G(mm)

Smallest

Arc

Radius

R(mm)

Shortest

Area

A(mm)

Total

Length

L(mm)

Clamping

Area

Length

B(mm)

Clamping

Area

Diameter

C(mm)

Bar 125 02 625 01 gt10 gt75 ~ 145 ~ 35 20

Table 3-3 Specifications for Round Bar

33 Experiment Procedure

1 Attaching the Strain Gauge to the Tensile Specimen

(1) Prepare 1 ASTM E8 compliant tensile specimen round bar as shown in figure 3-7

(2) Prepare Strain Gauge as those described in table 3-4

(3) Prepare other consumables and adhesive agent such as epoxy adhesive or

cyanoacrylate adhesive as shown in figure 3-8

48

Fig 3-7 Actual Tensile Specimen

Fig 3-8 Other Materials Used (Such as Alcohol gauze transparent tape adhesive)

Gage Type

EA-06-120LZ-120E

Resistance in ohms at 24∘C

1200plusmn03

Gage Factor at 24∘C

2075plusmn05

Transverse Sensitivity at 24∘C

(+07plusmn02)

Table 3-4 Specifications for Strain Gauge

2 Attaching Strain Gauge

As shown in following figures we shall explain the attachment of the strain gauge

(1) Use sand paper and a rasp to clean thoroughly the surface where the strain gauge will be

attached to

49

(a)

(2) Use alcohol to wash the surface where the strain gauge will be attached and use gauze to rub

it off

(b)

(3) Find a clean surface and clean it with alcohol and gauze

(c)

(4) Place the strain gauge in the clean surface Use a piece of transparent tape on top of the strain

gauge after securely placed rip it off the surface carefully

50

(d)

(5) Use a piece of white paper to mark the place where the strain gauge will be attached and in

this way we can make sure that the strain gauge will be placed as horizontally and vertically

correct as possible

(e)

(6) In the place where we had our mark place the strain gauge

(f)

(7) Carefully lift one side of the tape and apply some of the adhesive agent to both the strain

gauge and specimenrsquos surface

(g)

51

(8) We need to make sure that the gauge and the specimen will be firmly attached so we gently

apply pressure with our thumb

(h)

(9) After the adhesive is fully dry we can carefully rip off the tape

(i)

(10) We need to do the whole process twice one for the horizontally placed strain gauge and one

for the vertically placed strain gauge

52

(j)

(11) We now proceed to solder the wires to the strain gauge

(k)

(12) After soldering we use a Volt Multimeter to measure that there is no contact between wires

If there is none then the specimen is ready for testing

(l)

(13) We now need to measure a 5cm distance and mark it to check and compare the elongation

before and after the tensile testing

(m)

53

Fig 3-9 Specimen-Strain Gauge Process

3 Tensile Test

(1) Enter the computer application that controls the tensile testing machine

(2) Turn on the tensile testing machine main switch

(3) Adjust the hydraulic pump to go back to its original position

(4) Bring the lowering motor down to a distance enough so as to attach the tensile specimen to the

system open the clamps and secure the specimen

(a)

(5) Connect all the necessary wires to the strain indicator equipment

54

(b)

(6) Start the ascending motor and wait for the expansion

(c)

Fig 3-10 Specimen-Tensile Testing Process

4 Start the Test

(1) Enter the software application and enter some variables needed for the experiment in the

specific screen

(2) Go back to the main screen and press the [測試] (measure) button to start the test and auto

recording in the software

(3) After the specimen breaks the mechanical device will automatically stop and ask the user to

enter the total displacement We take out the specimen from the testing machine and adjust the

machinersquos position back to its original position

(4) Save the results information

(5) Record the results from the strain indicator

34 Results

From this experiment we can get the Poissonrsquos Ratio Youngrsquos Modulus and Yield Strength etc and

because of the slippage phenomenon in the clamp at the moment of the test then the Elastic Limit will

display some yield phenomena So omit any undesirable results we just take the Yield portion of the

results as reference

In the process of the experiment the most important part to attend to is the attaching of the strain

gauge because the gaugersquos purpose is to measure the strain developed during the test and this strain

might be very small If the gaugersquos angle change during the test ie is not well attached this will affect

the accuracy of the measurements of Poissonrsquos ratio and Youngrsquos modulus

55

The materials provided by the manufacturer are SUM 23 and SUM 43 steel round bars and these two

types of materials have been through different heat treatment processes so they can be sub-divided

further into untreated material heat-treated material and black surface heat treated material for the two

materials with heat treatment the treatment process and finished are different In the end we only have

the mechanical properties that were calculated after our research of these materials

All of the specifications are identical to those shown in figure 3-6

341 SUM 23

Fig 3-11 SUM 23 Untreated Material

Number 7 10

Hardness(HRB) 74 75

Yield Stress (MPa) 448 440

Tensile Strength (MPa) 544 560

Poissonrsquos Ratio 029 027

Youngrsquos Modulus (GPa) 203 210

Cut-off Area Shrinking () 42 41

Elongation () 1125 1011

Table 3-5 Mechanical Properties of SUM 23 Untreated

56

Stress-Strain Diagram

(a)

(b)

57

Fig 3-12 Stress-Strain Diagrams for (a) 7 Round Bar and (b) 10 Round Bar

Cut-Off Area

(a)

(b)

Fig 3-13 Cut-Off Area of (a) 7 Round Bar and (b) 10 Round Bar

58

SUM 23 Nickel Round Bar

Fig 3-14 SUM 23 Nickel Material

Number 1 2 3 4

Hardness(HRB) 48 50 49 48

Yield Stress (MPa) 370 370 380 400

Tensile Strength (MPa) 455 451 450 450

Poissonrsquos Ratio 028 046 029 026

Youngrsquos Modulus (GPa) 243 303 246 206

Cut-off Area Shrinking () 803 803 726 601

Elongation () 566 65 602 647

Table 3-6 Mechanical Properties of SUM 23 Nickel

59

Stress-Strain Diagram

(a)

60

(b)

(c)

(d)

61

Fig 3-15 Stress-Strain Diagrams for (a) 1 Round Bar (b) 2 Round Bar (c) 3 Round Bar and (d)

4 Round Bar

Cut-Off Area

(a)

(b)

62

(c)

(d)

Fig 3-16 Cut-Off Area of (a) 1 Round Bar (b) 2 Round Bar (c) 3 Round Bar and (d) 4 Round

Bar

63

SUM 23 Black Surface Round Bar

Fig 3-17 SUM 23 Black Surface Material

Number 1 2 3

Hardness(HRB) 51 50 51

Yield Stress (MPa) 378 371 369

Tensile Strength (MPa) 467 465 464

Poissonrsquos Ratio 03 016 04

Youngrsquos Modulus (GPa) 215 266 266

Cut-off Area Shrinking () 986 94 848

Elongation () 748 805 761

Table 3-7 Mechanical Properties of SUM 23 Black Surface Material

64

Stress-Strain Diagram

(a)

(b)

65

(c)

Fig 3-18 Stress-Strain Diagrams for (a) 1 Round Bar 2 Round Bar and (c) 3 Round Bar

Cut-Off Surface

(a)

66

(b)

(c)

Fig 3-19 Cut-Off Surface of (a) 1 Round Bar 2 Round Bar and (c) 3 Round Bar

67

342 SUM 43

Fig 3-20 Untreated SUM 43 Untreated Material

Number 1 5

Hardness(HRB) 76 75

Yield Stress (MPa) 572 594

Tensile Strength (MPa) 743 785

Poissonrsquos Ratio 027 029

Youngrsquos Modulus (GPa) 200 202

Cut-off Area Shrinking () 338 2944

Elongation () 857 894

Table 3-8 Mechanical Properties of SUM 43 Untreated

68

Stress-Strain Diagrams

(a)

(b)

Fig 3-21 Stress-Strain Diagrams for SUM 43 (a) 1 Round Bar and (b) 5 Round Bar

69

Cut-Off Area

(a)

(b)

Fig 3-22 Cut-Off Area of SUM 43 (a) 1 Round Bar and (b) 5 Round Bar

70

SUM 43 Nickel Round Bar

Fig 3-23 SUM 43 Nickel Material

Number 4 5

Hardness(HRB) 51 50

Yield Stress (MPa) 1580 1544

Tensile Strength (MPa) 1639 1625

Poissonrsquos Ratio 03 028

Youngrsquos Modulus (GPa) 194 201

Cut-off Area Shrinking () 1697 137

Elongation () 376 265

Table 3-9 Mechanical Properties of SUM 43 Nickel

71

Stress-Strain Diagrams

(a)

(b)

Fig 3-24 Stress-Strain Diagrams for (a) 4 Round Bar and (b) 5 Round Bar

72

Cut-Off Area

(a)

(b)

Fig 3-25 Cut-Off Area of (a) 4 Round Bar and (b) 5 Round Bar

73

SUM 43 Black Surface Material

Fig 3-26 SUM 43 Black Surface Material

Number 3 5

Hardness(HRB) 56 56

Yield Stress (MPa) 1416 1361

Tensile Strength (MPa) 1591 1402

Poissonrsquos Ratio 029 031

Youngrsquos Modulus (GPa) 200 202

Cut-off Area Shrinking () 139 124

Elongation () 24 24

Table 3-10 Mechanical Properties of SUM 43 Black Surface Material

74

Stress-Strain Diagrams

0 2 4 6 8 10 12 14

-200

0

200

400

600

800

1000

1200

1400

1600

1800

應力 (MPa)

應變()

(a)

0 2 4 6 8 10

-200

0

200

400

600

800

1000

1200

1400

1600

應力

(MPa)

位移 ()

(b)

Fig 3-27 Stress-Strain Diagrams for (a) 3 Round Bar and (b) 5 Round Bar

(Note These curves were formulated using Visual Solutions Inc VisSim Software)

75

Cut-Off Area

(a)

(b)

Fig 3-28 Cut-Off Area of (a) 3 Round Bar and (b) 5 Round Bar

76

The force value (N) was retrieved from the Universal Testing Machine

The Poissonrsquos Ratio (ε) is calculated as

ε =

the values for the Poissonrsquos Ratio are in average around 0297

The Youngrsquos Modulus (E) is calculated as

E =

Where

Stress =

Cross-sectional Area =

where D is the Diameter

The value for D was in average around 1258 mm

The values shown by the computer because there is Slippage phenomena between the Clamp and the

specimen will not be taken into consideration for the elongation strain and Youngrsquos modulus and we will

refer to the values that we have meticulously calculated

77

Chapter 4 AR COATING IN DEPTH

41 Experimentrsquos Purpose and Principles

By means of a vacuum chamber and several other instruments we intend to apply Anti-Reflective

Coating using deposition process to a laser diode and in this way reduce its refraction so as to make it

lose less light in the process of amplification and we can control certain wavelengths we want produced

for certain desired applications in our case we are attempting to re-create a Bose-Einstein Condensate

An optimal BEC apparatus is shown in figure 4-1

Fig 4-1 BEC Apparatus

The main point of this experiment is to build a vacuum chamber system attach all the instrumentation

needed (Vacuum pump deposition meter and voltmeter) and use it to apply AR coating to a laser diode

After we have accomplished the AR coating other team will be in charge of designing the BEC apparatus

and use the results of our research

78

42 Experimentrsquos Equipment

421 Vacuum Chamber

For this research we designed a vacuum chamber whose main body is shown in figure 4-2 Its

dimensions are

Width 240 mm

Length 240 mm

Height 200 mm

Outer Diameter 4 in

Inner Diameter 15 in

Fig 4-2 Vacuum Chamber Main Body

The chamber is made up of 6 pass ways pass way A is the connection with the Laser Deposition

Equipment pass way B is the connection with the Turbo Pump and pass way C is for the connection with

the Deposition Source

A

C

B

79

Pass way C is for the deposition source as mentioned above This is a system where a thermal

resistance is heated by passing a high current through it which heats up a filament boat (made of tungsten)

where the material to be evaporated is place We control the temperature as such that the material will

evaporate and the heat will not cause the filament boat to crack

Because P = Isup2 R (where P is power I is current and R is resistance) to avoid the current to flow

where it is not desired we decided that the material for the Thermocouple shown in figure 4-3 should be

Copper ᴓ 63 mm We choose it that way because Copper has very good heat dissipation characteristics

and the resistance value is low It can reduce the value of the current enough to make the thermocouple to

create heat

Fig 4-3 Thermocouple

To the thermocouple we attach the tungsten filament boat We need to take notice of materials to be

used in this design because when using high current the tungsten filament boar will heat up and so the

material must be able to keep up with the heating potential of tungsten and has a low coefficient of heat

dissipation to avoid the tungsten to fail when heating up and therefore not evaporating Considering all

this we decide to use Stainless Steel

Because this clamp will be assembled inside the chamber after many revisions it was determined it

will have the shape shown in figure 4-4

Fig 4-4 Filament Boat Clamp Design

80

For the tungsten filament boat we bought the product from a distributor The dimensions are

Length 100 mm

Width 10 mm

Height 1 mm

Our thermocouple is 15 in but the pass way C is 4 in so we need to attach a Flange that connects

15in to 4in Because these specifications are quite difficult to achieve by Milling we had to use

electrical wire cutting

For the laser clamping system where the laser that is going to be AR coated will be placed will be

connected to pass way A the assembly is shown in figure 4-5 below

Fig 4-5 Cover Assembly

For this design we used an O-ring instead of a gasket so as to save time The design of the assembly

where the laser will be placed is shown in figure 4-6

Fig 4-6 Upper Cover Inner Assembly

D

E

F

81

Point D is the plate in the assembly where the laser diode will be fixed Because of the easy

processing we decide to use Aluminum and it is screwed to the top cover Point E is the connection for

the Quartz crystal resonator and it is designed in the same as point F in this way the results of the quartz

microbalance system will be more accurate in real time Point F is the final resting place for the laser

diode We use a Thor Labs Base with dimensions of ᴓ 9mm and ᴓ 56mm for two different size laser

diodes It just needs to be plugged in for easy installation

From figure 4-6 we know that the system needs signal system connections and because of the

change in temperature inside the chamber this could affect the functioning of the quartz microbalance so

we also need to install water tubes for cooling This is shown in figure 4-7 below

Fig 4-7 Diagram of Upper Cover Connections

In figure 4-8 we show the Feed through connections and their functions

Fig 4-8 Feed through Diagram

82

1 SQM-160 wire 5 Laser Connection 1 (Vin)

2 SQM-160 (G) 6 Laser Connection 2 (G)

3 K-Type-1 7 Laser Connection 3 (PD)

4 K-Type-2 8 Not In Use

The fully assembled chamber is shown in figure 4-9

Fig 4-9 Fully Assembled Chamber

422 Quartz Crystal Microbalance

For measuring the deposition on our target for coating we used the Inficon SQM-160 RateThickness

Monitor It is an easy to use instrument for measuring many types of thin-film coatings as shown in

figure 4-10

(a) Front Panel (b) Back Panel

Fig 4-10 Inficon SQM-160

83

Table 4-1 shows the technical specifications for this equipment

Number of sensors 2 Standard 4 additional optional

Sensor Frequency Range 40 MHz ~ 60 MHz

Reference Frequency Accuracy 002

Thickness Display Resolution 1 Aring

Thickness Resolution 015 Aring (Std) 0037 Aring (Hi Res)

Density of Stored Films 05-9999 gmcc

Tooling 10-399

Z-Factor 010-1000

Final Thickness 0000-9999k Aring

Measurement Period 15 to 2 sec

Simulation Mode Yes

Frequency Mode Yes

Rate Resolution 011 Arings

Dual Crystal Yes

Etch Mode Yes

Crystal Tooling 10-399

Crystal Fail Min Max 40 to 60 MHz 41 to 61 MHz

Power 100-120 200-240~plusmn10 nominal 20W

Operation Environment 0degC ~ 50degC

0 ~ 80 RH non-condensing

0 ~ 2000 meters

Class 1 Equipment

Pollution Degree 2

Rack Dimensions 885mm x 2127mm x 1969mm

Weight 27 kg

Table 4-1 Inficon SQM-160 RateThickness Monitor Specs

84

To the SQM-160 we need to connect an Oscillator We use the Sigma Instruments Remote Oscillator

Ser No 2 268 as shown in figure 4-11

Fig 4-11 Sigma Instruments Remote Oscillator

The connections diagram is shown in figure 4-12

Fig 4-12 SQM-160 Connections Diagram

85

423 Turbo Pump

For our experiments we used the Pfeiffer TCP 015 Electronic Drive Unit shown below in figure 4-13

Table 4-2 shows the technical specifications for this equipment

(a) Front Panel (b) Back Panel

Fig 4-13 Pfeiffer TCP 015 Electronic Drive

Connection Voltage (100V) 90-112

Mains Frequency 5060 Hz

Start-up Current 22 A

Nominal Frequency 1500 Hz

Rotation Speed 10V = 1500Hz plusmn2

Analog Output Current 10 V = 25 A plusmn 5

Rotation Speed Switchpoint 750 Hz

Works Setting 8 min

Permissible Ambient Temperature 0degC ~ 40degC

Dimensions Front Panel 1285mm x 1063mm

Insertion Length 227mm

Weight 27 Kg

Table 4-2 Pfeiffer TCP 015 Electronic Drive Specs

86

The connections diagram is shown in figure 4-14

Fig 4-14Connections Diagram for Pfeiffer TCP 015

To measure the pressure inside the chamber we use the Granville Phillips 375 Convectron Vacuum

Pressure Controller shown in figure 4-15

(a) Front Panel (b) Back Panel

Fig 4-15 Granville Phillips 375 Convectron

87

Its dimensions are shown in figure 4-16

Fig 4-16 Dimensions of Convectron

Table 4-3 shows the technical specifications for this equipment

Table 4-3 Granville Phillips 375 Convectron Vacuum Pressure Controller Specs

88

424 Multimeter

For our experiment we used the Keithley 2000 Digital Multimeter as shown in figure 4-17

(a) Front Panel (b) Back Panel

Fig 4-17 Keithley Model 2000 6-12-Digit Digital Multimeter

Its technical specifications are shown in table 4-4

Table 4-4 Keithley Model 2000 6-12-Digit Digital Multimeter Specs

89

43 Experiment Procedure

1 Connecting together the equipment and the chamber

(1) We first connect the resonator to the thickness monitor and connect the other side to the

chamber

(2) We now connect the flexible tubes to the turbo pump on one side and to the chamber on the

other

(3) We need to check that tubes are tightly connected to avoid any leaks in the vacuum pumping

process which will not allow us to get to our goal of Torr As shown in figure 4-18

(4) Connect the convectron to the system as shown in figure 4-19

Fig 4-18 checking for leaks using alcohol

Fig 4-19 Convectron attached to System

90

(5) Attach the clamps of the Multimeter to the bottom of the chamber as shown in figure 4-20

(6) Place the Quartz crystal in place

(7) Close tight vacuum chamber

(8) Connect all electrical appliances to power source

Fig 4-20 Multimeter Connections

2 Starting up the System

(1) We turn on all the devices as such Check all systems are ready to function Reset all values

that might be left over from previous tests

(2) Start the thickness monitor and set all values for this experiment In our case we got to testing

the system but not actual coating So we used the simulation mode of the thickness monitor as

shown in figure 4-21

Fig 4-21 Simulation Mode

91

(3) Start the turbo pump Make sure the lid on the vacuum chamber is tightly closed

(4) Start convectron and record initial pressure

(5) Start Multimeter and record initial current

3 Coating Process

(1) If we have the deposition material inside the filament boat the power source for the high

current must be started as well

(2) Record all initial values for thickness current pressure

(3) For an ideal experiment we need a thickness of around 101 nm a pressure of Torr and

a current of 300 A

44 Results

From previous experiments we have shown that we can turn a LED into a laser by means of AR

Coating In figure 4-22 shown below we can compare the actual results of a Diode before and after AR

coating From the blue line we can see that when the diode is at a current of 15mA its light will change

from LED to laser and if we look at the red line its critical current is around 30 to 35 mA

Fig 4-22 AR Coating Comparison for Laser Diodes

This means that the light emitted is not as strong as if the diode had been coated because inside the

chamber there must be some excitation first so the reflectivity of both sides inside the diode must be high

So because of the coating in one of the sides we have opened a door and let the light come out so the

critical current is risen as such and will be higher value than that of before the coating

92

In the following figures we can see the difference between before and after coating in a material The

thickness is around 1016 nm for this material

Fig 4-23 Before Coating

Fig 4-24 After Coating

93

Chapter 5 CONCLUSIONS AND RECOMMENDATIONS

51 Conclusions

For the first part of this independent study taking into consideration the data that came out of our

research and that sent by the provider we can say

1 SUM 23 after heat treatment will unexpectedly develop cracking in the middle of the tensile

testing process and suddenly break

2 Itrsquos possible that in the process of heat treatment to the SUM 23 material the treatment was not

uniform and this will create a pre-loaded moment force on one side that pushes on the other side

of the specimen resulting in material deformation

3 In the process of attaching the strain gauges to the materials it is very easy to make errors due to

poor adhesion or sudden removal in the tensile testing process

For our second part of the independent study the following can be made

1 At the beginning of this independent study we had no idea what Bose-Einstein Condensate was

or what was its purpose After much literature we finally comprehended the basic principles to

put into practice for our research

2 Our systemrsquos basic working principles and equipmentrsquos complexity are a little difficult to grasp

but hopefully we were able to understand enough of it

3 Theoretically from relation between the power and current we can know the advantages and

disadvantages of AR Coating

4 We were able to assemble the system and run test on its functions Even though we were able to

do this there is still much more work left to do with this system

52 Recommendations

For the Tensile Testing the following can be said

1 Ask the provider to check on the process of heat treatment on the SUM 23 material and give

them the information we have gathered through our test so they can correct for the mechanical

properties found if any change is needed

2 To avoid the problem of the inaccuracy of the poor adhesion of strain gauges we can attach

multiple strain gauges to the same one specimen so as to correlate data and improve our results

For the AR Coating the following can be said

1 We need to make sure that there are no physical defects on the main body of the chamber so as to

achieve maximum efficiency in the vacuum process If there was then the vacuum will arrive to

certain point and then start to decrease

2 It would be preferable to add some sort of visual aid that will allow the user to check the inside of

the chamber without actually opening it This will help us determine at what times we should

manipulate the current to better evaporate the substrate

94

REFERENCES

[1] A L Window Strain Gauge Technology Elsevier Applied Science London and New York 2nd

Edition 1992

[2] CC Perry and HR Lissner Strain Gauge Primer McGraw-Hill Book Co Inc New York 1955

[3] James W Dally William F Riley McGraw-Hill 1978

[4] University of Colorado Boulder BEC - What is it and where did the idea come from

httpwwwcoloradoeduphysics2000becwhat_is_ithtml

[5] Ultraslow Light amp Bose-Einstein Condensates Two-way Control with Coherent Light amp Atom

Fields Harvard Hau Lab Dr Lene Vestergaard Hau Optics amp Photonics News 16 1995

[6] The Art of Taming Light Ultra-slow and Stopped Light Harvard Hau Lab Dr Lene

Vestergaard Hau Europhysics News 2004

[7] Nonlinear Optics Shocking Superfluids Harvard Hau Lab Dr Lene Vestergaard Hau Nature

Physics 2007

[8] Model P3 Strain Indicator and Recorder Instruction Manual Vishay Micro-Measurements 2005

[9] Granville-Phillips Series 375 Convectron Vacuum Gauge Controller Instruction Manual Brooks

Automation 2008

[10] Effect of Film Thickness on the Validity of the Sauerbrey Equation for Hydrated Polyelectrolyte

Films Vogt Lin Wu White 2004

[11] Quartz Crystal Microbalance Study of DNA Immobilization and Hybridization for DNA Sensor

Development Chang Zhao 2008

[12] Installation of Strain Gages with SR-4 PrecoatAdhesive Vishay Micro-Measurements 2005

[13] Strain Gauge Measurement ndash A Tutorial National Instruments 1998

[14] Correlation between Vickers Hardness Number and Yield Stress of Cold-Formed Products

Yavuz Tekkaya

[15] httpsenwikipediaorg

Page 44: PC Hinge Materials Testing and AR Laser Diode Coating

44

Input Connections Tool Free eccentric lever release

4-channel input

Wire diameter16-28AWG

Bridge Configurations Quarter- Half- and Full Bridge

Bridge Impedance 60-2000Ω

Display 128 64 pixel FSTN positive gray LCD

Data Conversion AD Converter filter

Measurement Range Resolution Strain Range plusmn155mVV

Resolution plusmn00005mVV

Measurement Accuracy plusmn01 of reading plusmn3 counts

Gage Factor Control 0500-9900

Balance Control Software either manual or automatic

Bridge Excitation 15VDC nominal

Communication Interface USB Cable Included

Data Storage Removable Media Card

Shunt Calibration Across bridge completion resistors controlled

by software When Gage Factor=200

120Ω350Ω1000Ω

Analog Output Value 0 to 25V max

Ranges plusmn320 microε plusmn3200 microε plusmn32000 microε

Error 05 output voltage +5mV

Max Error 14 output voltage + 20mV

Update rate 480 samplessec

Output Load 2000Ω

Power Battery Two Alkaline D cells

Battery life 400 hours typ

USB 5V 100mA

Operational Environment Temperature 0-50

Humidity Up to 90 Non-condensing

Case Aluminum Alloy

Size and Weight 228times152times152(mm) 20(kg)

Table 3-2 Vishay Micro-Measurements Model P3 Strain Indicator and Recorder Specs

45

323 Strain Gauge

The strain gaugersquos main basic principle is to use a resistancersquos characteristics to measure the strain

The inside connections of the strain indicator are shown in figure 3-5

Fig 3-5 Inner Connections

As shown above this is a quarter-bridge connection We connect equal-length 3 wires to the 2

connections allowed by the strain gauge wire 1 and 3 can be used to cancel out the effects of temperature

to the resistance and because of the addition of wires 1 and 3 wire 2 can directly measure the experiment

results from the strain gauge and therefore the strain developed with no influence of temperature

If there were no two measuring leads then the relations will be

R 4 =R g +2R L

Where Rg is the Strain Gauge Value and RL is the wire resistance then

4

4

R

R=

Lg

g

RR

R

2

=

gL

gg

RR

RR

21

amp

4

4

R

R=

g

g

R

R(1- L)

Where L is the Signal Loss Factor and so

L =gL

gL

RR

RR

21

2

g

L

R

2R if

g

L

R

2Rltlt1

46

(Actual Value R g =120R L =08g

L

R

2Ris always much smaller than 1)

R 4 =R g +2R LR 2 =R 3 =rR gR 1 =R g 32 RR =0

V 0 =V 2)1( r

r

(

4

4

R

R-

1

1

R

R)

The first term describes loss attenuation effects second term describes loss of balancing capabilities

effects

V 0 =V 2)1( r

r

[

)2

(Lg

g

RR

R

+

T

Lg

g

RR

R

)

2( + T

Lg

L

RR

R

)

2

2( -(

g

g

R

R) T ]

The first term describes loss attenuation effects and loss of balancing capabilities effects the second

third and fourth terms describe the temperature effects on the wire

For the three-wire method we have

L =gL

gL

RR

RR

1

g

L

R

R if

g

L

R

Rltlt1

V 0 =V 2)1( r

r

[

)(Lg

g

RR

R

+

T

Lg

g

RR

R

)( + T

Lg

L

RR

R

)

2( -

T

Lg

g

RR

R

)( - T

Lg

L

RR

R

)

2( ]

V 0 = V2)1( r

r

)(

Lg

g

RR

R

In the last four terms inside parenthesis we can see the effects of temperature being cancelled out and the

effect on first term is not great so this is the reason why in our research we use three wires

47

324 Specimen Measurements

The tensile specimens used in this research are compliant of ASTM E8 Tensile parameters as shown

in figure 3-6

Fig 3-6 Tensile Specimen

Diameter

D(mm)

Gauge

Length

G(mm)

Smallest

Arc

Radius

R(mm)

Shortest

Area

A(mm)

Total

Length

L(mm)

Clamping

Area

Length

B(mm)

Clamping

Area

Diameter

C(mm)

Bar 125 02 625 01 gt10 gt75 ~ 145 ~ 35 20

Table 3-3 Specifications for Round Bar

33 Experiment Procedure

1 Attaching the Strain Gauge to the Tensile Specimen

(1) Prepare 1 ASTM E8 compliant tensile specimen round bar as shown in figure 3-7

(2) Prepare Strain Gauge as those described in table 3-4

(3) Prepare other consumables and adhesive agent such as epoxy adhesive or

cyanoacrylate adhesive as shown in figure 3-8

48

Fig 3-7 Actual Tensile Specimen

Fig 3-8 Other Materials Used (Such as Alcohol gauze transparent tape adhesive)

Gage Type

EA-06-120LZ-120E

Resistance in ohms at 24∘C

1200plusmn03

Gage Factor at 24∘C

2075plusmn05

Transverse Sensitivity at 24∘C

(+07plusmn02)

Table 3-4 Specifications for Strain Gauge

2 Attaching Strain Gauge

As shown in following figures we shall explain the attachment of the strain gauge

(1) Use sand paper and a rasp to clean thoroughly the surface where the strain gauge will be

attached to

49

(a)

(2) Use alcohol to wash the surface where the strain gauge will be attached and use gauze to rub

it off

(b)

(3) Find a clean surface and clean it with alcohol and gauze

(c)

(4) Place the strain gauge in the clean surface Use a piece of transparent tape on top of the strain

gauge after securely placed rip it off the surface carefully

50

(d)

(5) Use a piece of white paper to mark the place where the strain gauge will be attached and in

this way we can make sure that the strain gauge will be placed as horizontally and vertically

correct as possible

(e)

(6) In the place where we had our mark place the strain gauge

(f)

(7) Carefully lift one side of the tape and apply some of the adhesive agent to both the strain

gauge and specimenrsquos surface

(g)

51

(8) We need to make sure that the gauge and the specimen will be firmly attached so we gently

apply pressure with our thumb

(h)

(9) After the adhesive is fully dry we can carefully rip off the tape

(i)

(10) We need to do the whole process twice one for the horizontally placed strain gauge and one

for the vertically placed strain gauge

52

(j)

(11) We now proceed to solder the wires to the strain gauge

(k)

(12) After soldering we use a Volt Multimeter to measure that there is no contact between wires

If there is none then the specimen is ready for testing

(l)

(13) We now need to measure a 5cm distance and mark it to check and compare the elongation

before and after the tensile testing

(m)

53

Fig 3-9 Specimen-Strain Gauge Process

3 Tensile Test

(1) Enter the computer application that controls the tensile testing machine

(2) Turn on the tensile testing machine main switch

(3) Adjust the hydraulic pump to go back to its original position

(4) Bring the lowering motor down to a distance enough so as to attach the tensile specimen to the

system open the clamps and secure the specimen

(a)

(5) Connect all the necessary wires to the strain indicator equipment

54

(b)

(6) Start the ascending motor and wait for the expansion

(c)

Fig 3-10 Specimen-Tensile Testing Process

4 Start the Test

(1) Enter the software application and enter some variables needed for the experiment in the

specific screen

(2) Go back to the main screen and press the [測試] (measure) button to start the test and auto

recording in the software

(3) After the specimen breaks the mechanical device will automatically stop and ask the user to

enter the total displacement We take out the specimen from the testing machine and adjust the

machinersquos position back to its original position

(4) Save the results information

(5) Record the results from the strain indicator

34 Results

From this experiment we can get the Poissonrsquos Ratio Youngrsquos Modulus and Yield Strength etc and

because of the slippage phenomenon in the clamp at the moment of the test then the Elastic Limit will

display some yield phenomena So omit any undesirable results we just take the Yield portion of the

results as reference

In the process of the experiment the most important part to attend to is the attaching of the strain

gauge because the gaugersquos purpose is to measure the strain developed during the test and this strain

might be very small If the gaugersquos angle change during the test ie is not well attached this will affect

the accuracy of the measurements of Poissonrsquos ratio and Youngrsquos modulus

55

The materials provided by the manufacturer are SUM 23 and SUM 43 steel round bars and these two

types of materials have been through different heat treatment processes so they can be sub-divided

further into untreated material heat-treated material and black surface heat treated material for the two

materials with heat treatment the treatment process and finished are different In the end we only have

the mechanical properties that were calculated after our research of these materials

All of the specifications are identical to those shown in figure 3-6

341 SUM 23

Fig 3-11 SUM 23 Untreated Material

Number 7 10

Hardness(HRB) 74 75

Yield Stress (MPa) 448 440

Tensile Strength (MPa) 544 560

Poissonrsquos Ratio 029 027

Youngrsquos Modulus (GPa) 203 210

Cut-off Area Shrinking () 42 41

Elongation () 1125 1011

Table 3-5 Mechanical Properties of SUM 23 Untreated

56

Stress-Strain Diagram

(a)

(b)

57

Fig 3-12 Stress-Strain Diagrams for (a) 7 Round Bar and (b) 10 Round Bar

Cut-Off Area

(a)

(b)

Fig 3-13 Cut-Off Area of (a) 7 Round Bar and (b) 10 Round Bar

58

SUM 23 Nickel Round Bar

Fig 3-14 SUM 23 Nickel Material

Number 1 2 3 4

Hardness(HRB) 48 50 49 48

Yield Stress (MPa) 370 370 380 400

Tensile Strength (MPa) 455 451 450 450

Poissonrsquos Ratio 028 046 029 026

Youngrsquos Modulus (GPa) 243 303 246 206

Cut-off Area Shrinking () 803 803 726 601

Elongation () 566 65 602 647

Table 3-6 Mechanical Properties of SUM 23 Nickel

59

Stress-Strain Diagram

(a)

60

(b)

(c)

(d)

61

Fig 3-15 Stress-Strain Diagrams for (a) 1 Round Bar (b) 2 Round Bar (c) 3 Round Bar and (d)

4 Round Bar

Cut-Off Area

(a)

(b)

62

(c)

(d)

Fig 3-16 Cut-Off Area of (a) 1 Round Bar (b) 2 Round Bar (c) 3 Round Bar and (d) 4 Round

Bar

63

SUM 23 Black Surface Round Bar

Fig 3-17 SUM 23 Black Surface Material

Number 1 2 3

Hardness(HRB) 51 50 51

Yield Stress (MPa) 378 371 369

Tensile Strength (MPa) 467 465 464

Poissonrsquos Ratio 03 016 04

Youngrsquos Modulus (GPa) 215 266 266

Cut-off Area Shrinking () 986 94 848

Elongation () 748 805 761

Table 3-7 Mechanical Properties of SUM 23 Black Surface Material

64

Stress-Strain Diagram

(a)

(b)

65

(c)

Fig 3-18 Stress-Strain Diagrams for (a) 1 Round Bar 2 Round Bar and (c) 3 Round Bar

Cut-Off Surface

(a)

66

(b)

(c)

Fig 3-19 Cut-Off Surface of (a) 1 Round Bar 2 Round Bar and (c) 3 Round Bar

67

342 SUM 43

Fig 3-20 Untreated SUM 43 Untreated Material

Number 1 5

Hardness(HRB) 76 75

Yield Stress (MPa) 572 594

Tensile Strength (MPa) 743 785

Poissonrsquos Ratio 027 029

Youngrsquos Modulus (GPa) 200 202

Cut-off Area Shrinking () 338 2944

Elongation () 857 894

Table 3-8 Mechanical Properties of SUM 43 Untreated

68

Stress-Strain Diagrams

(a)

(b)

Fig 3-21 Stress-Strain Diagrams for SUM 43 (a) 1 Round Bar and (b) 5 Round Bar

69

Cut-Off Area

(a)

(b)

Fig 3-22 Cut-Off Area of SUM 43 (a) 1 Round Bar and (b) 5 Round Bar

70

SUM 43 Nickel Round Bar

Fig 3-23 SUM 43 Nickel Material

Number 4 5

Hardness(HRB) 51 50

Yield Stress (MPa) 1580 1544

Tensile Strength (MPa) 1639 1625

Poissonrsquos Ratio 03 028

Youngrsquos Modulus (GPa) 194 201

Cut-off Area Shrinking () 1697 137

Elongation () 376 265

Table 3-9 Mechanical Properties of SUM 43 Nickel

71

Stress-Strain Diagrams

(a)

(b)

Fig 3-24 Stress-Strain Diagrams for (a) 4 Round Bar and (b) 5 Round Bar

72

Cut-Off Area

(a)

(b)

Fig 3-25 Cut-Off Area of (a) 4 Round Bar and (b) 5 Round Bar

73

SUM 43 Black Surface Material

Fig 3-26 SUM 43 Black Surface Material

Number 3 5

Hardness(HRB) 56 56

Yield Stress (MPa) 1416 1361

Tensile Strength (MPa) 1591 1402

Poissonrsquos Ratio 029 031

Youngrsquos Modulus (GPa) 200 202

Cut-off Area Shrinking () 139 124

Elongation () 24 24

Table 3-10 Mechanical Properties of SUM 43 Black Surface Material

74

Stress-Strain Diagrams

0 2 4 6 8 10 12 14

-200

0

200

400

600

800

1000

1200

1400

1600

1800

應力 (MPa)

應變()

(a)

0 2 4 6 8 10

-200

0

200

400

600

800

1000

1200

1400

1600

應力

(MPa)

位移 ()

(b)

Fig 3-27 Stress-Strain Diagrams for (a) 3 Round Bar and (b) 5 Round Bar

(Note These curves were formulated using Visual Solutions Inc VisSim Software)

75

Cut-Off Area

(a)

(b)

Fig 3-28 Cut-Off Area of (a) 3 Round Bar and (b) 5 Round Bar

76

The force value (N) was retrieved from the Universal Testing Machine

The Poissonrsquos Ratio (ε) is calculated as

ε =

the values for the Poissonrsquos Ratio are in average around 0297

The Youngrsquos Modulus (E) is calculated as

E =

Where

Stress =

Cross-sectional Area =

where D is the Diameter

The value for D was in average around 1258 mm

The values shown by the computer because there is Slippage phenomena between the Clamp and the

specimen will not be taken into consideration for the elongation strain and Youngrsquos modulus and we will

refer to the values that we have meticulously calculated

77

Chapter 4 AR COATING IN DEPTH

41 Experimentrsquos Purpose and Principles

By means of a vacuum chamber and several other instruments we intend to apply Anti-Reflective

Coating using deposition process to a laser diode and in this way reduce its refraction so as to make it

lose less light in the process of amplification and we can control certain wavelengths we want produced

for certain desired applications in our case we are attempting to re-create a Bose-Einstein Condensate

An optimal BEC apparatus is shown in figure 4-1

Fig 4-1 BEC Apparatus

The main point of this experiment is to build a vacuum chamber system attach all the instrumentation

needed (Vacuum pump deposition meter and voltmeter) and use it to apply AR coating to a laser diode

After we have accomplished the AR coating other team will be in charge of designing the BEC apparatus

and use the results of our research

78

42 Experimentrsquos Equipment

421 Vacuum Chamber

For this research we designed a vacuum chamber whose main body is shown in figure 4-2 Its

dimensions are

Width 240 mm

Length 240 mm

Height 200 mm

Outer Diameter 4 in

Inner Diameter 15 in

Fig 4-2 Vacuum Chamber Main Body

The chamber is made up of 6 pass ways pass way A is the connection with the Laser Deposition

Equipment pass way B is the connection with the Turbo Pump and pass way C is for the connection with

the Deposition Source

A

C

B

79

Pass way C is for the deposition source as mentioned above This is a system where a thermal

resistance is heated by passing a high current through it which heats up a filament boat (made of tungsten)

where the material to be evaporated is place We control the temperature as such that the material will

evaporate and the heat will not cause the filament boat to crack

Because P = Isup2 R (where P is power I is current and R is resistance) to avoid the current to flow

where it is not desired we decided that the material for the Thermocouple shown in figure 4-3 should be

Copper ᴓ 63 mm We choose it that way because Copper has very good heat dissipation characteristics

and the resistance value is low It can reduce the value of the current enough to make the thermocouple to

create heat

Fig 4-3 Thermocouple

To the thermocouple we attach the tungsten filament boat We need to take notice of materials to be

used in this design because when using high current the tungsten filament boar will heat up and so the

material must be able to keep up with the heating potential of tungsten and has a low coefficient of heat

dissipation to avoid the tungsten to fail when heating up and therefore not evaporating Considering all

this we decide to use Stainless Steel

Because this clamp will be assembled inside the chamber after many revisions it was determined it

will have the shape shown in figure 4-4

Fig 4-4 Filament Boat Clamp Design

80

For the tungsten filament boat we bought the product from a distributor The dimensions are

Length 100 mm

Width 10 mm

Height 1 mm

Our thermocouple is 15 in but the pass way C is 4 in so we need to attach a Flange that connects

15in to 4in Because these specifications are quite difficult to achieve by Milling we had to use

electrical wire cutting

For the laser clamping system where the laser that is going to be AR coated will be placed will be

connected to pass way A the assembly is shown in figure 4-5 below

Fig 4-5 Cover Assembly

For this design we used an O-ring instead of a gasket so as to save time The design of the assembly

where the laser will be placed is shown in figure 4-6

Fig 4-6 Upper Cover Inner Assembly

D

E

F

81

Point D is the plate in the assembly where the laser diode will be fixed Because of the easy

processing we decide to use Aluminum and it is screwed to the top cover Point E is the connection for

the Quartz crystal resonator and it is designed in the same as point F in this way the results of the quartz

microbalance system will be more accurate in real time Point F is the final resting place for the laser

diode We use a Thor Labs Base with dimensions of ᴓ 9mm and ᴓ 56mm for two different size laser

diodes It just needs to be plugged in for easy installation

From figure 4-6 we know that the system needs signal system connections and because of the

change in temperature inside the chamber this could affect the functioning of the quartz microbalance so

we also need to install water tubes for cooling This is shown in figure 4-7 below

Fig 4-7 Diagram of Upper Cover Connections

In figure 4-8 we show the Feed through connections and their functions

Fig 4-8 Feed through Diagram

82

1 SQM-160 wire 5 Laser Connection 1 (Vin)

2 SQM-160 (G) 6 Laser Connection 2 (G)

3 K-Type-1 7 Laser Connection 3 (PD)

4 K-Type-2 8 Not In Use

The fully assembled chamber is shown in figure 4-9

Fig 4-9 Fully Assembled Chamber

422 Quartz Crystal Microbalance

For measuring the deposition on our target for coating we used the Inficon SQM-160 RateThickness

Monitor It is an easy to use instrument for measuring many types of thin-film coatings as shown in

figure 4-10

(a) Front Panel (b) Back Panel

Fig 4-10 Inficon SQM-160

83

Table 4-1 shows the technical specifications for this equipment

Number of sensors 2 Standard 4 additional optional

Sensor Frequency Range 40 MHz ~ 60 MHz

Reference Frequency Accuracy 002

Thickness Display Resolution 1 Aring

Thickness Resolution 015 Aring (Std) 0037 Aring (Hi Res)

Density of Stored Films 05-9999 gmcc

Tooling 10-399

Z-Factor 010-1000

Final Thickness 0000-9999k Aring

Measurement Period 15 to 2 sec

Simulation Mode Yes

Frequency Mode Yes

Rate Resolution 011 Arings

Dual Crystal Yes

Etch Mode Yes

Crystal Tooling 10-399

Crystal Fail Min Max 40 to 60 MHz 41 to 61 MHz

Power 100-120 200-240~plusmn10 nominal 20W

Operation Environment 0degC ~ 50degC

0 ~ 80 RH non-condensing

0 ~ 2000 meters

Class 1 Equipment

Pollution Degree 2

Rack Dimensions 885mm x 2127mm x 1969mm

Weight 27 kg

Table 4-1 Inficon SQM-160 RateThickness Monitor Specs

84

To the SQM-160 we need to connect an Oscillator We use the Sigma Instruments Remote Oscillator

Ser No 2 268 as shown in figure 4-11

Fig 4-11 Sigma Instruments Remote Oscillator

The connections diagram is shown in figure 4-12

Fig 4-12 SQM-160 Connections Diagram

85

423 Turbo Pump

For our experiments we used the Pfeiffer TCP 015 Electronic Drive Unit shown below in figure 4-13

Table 4-2 shows the technical specifications for this equipment

(a) Front Panel (b) Back Panel

Fig 4-13 Pfeiffer TCP 015 Electronic Drive

Connection Voltage (100V) 90-112

Mains Frequency 5060 Hz

Start-up Current 22 A

Nominal Frequency 1500 Hz

Rotation Speed 10V = 1500Hz plusmn2

Analog Output Current 10 V = 25 A plusmn 5

Rotation Speed Switchpoint 750 Hz

Works Setting 8 min

Permissible Ambient Temperature 0degC ~ 40degC

Dimensions Front Panel 1285mm x 1063mm

Insertion Length 227mm

Weight 27 Kg

Table 4-2 Pfeiffer TCP 015 Electronic Drive Specs

86

The connections diagram is shown in figure 4-14

Fig 4-14Connections Diagram for Pfeiffer TCP 015

To measure the pressure inside the chamber we use the Granville Phillips 375 Convectron Vacuum

Pressure Controller shown in figure 4-15

(a) Front Panel (b) Back Panel

Fig 4-15 Granville Phillips 375 Convectron

87

Its dimensions are shown in figure 4-16

Fig 4-16 Dimensions of Convectron

Table 4-3 shows the technical specifications for this equipment

Table 4-3 Granville Phillips 375 Convectron Vacuum Pressure Controller Specs

88

424 Multimeter

For our experiment we used the Keithley 2000 Digital Multimeter as shown in figure 4-17

(a) Front Panel (b) Back Panel

Fig 4-17 Keithley Model 2000 6-12-Digit Digital Multimeter

Its technical specifications are shown in table 4-4

Table 4-4 Keithley Model 2000 6-12-Digit Digital Multimeter Specs

89

43 Experiment Procedure

1 Connecting together the equipment and the chamber

(1) We first connect the resonator to the thickness monitor and connect the other side to the

chamber

(2) We now connect the flexible tubes to the turbo pump on one side and to the chamber on the

other

(3) We need to check that tubes are tightly connected to avoid any leaks in the vacuum pumping

process which will not allow us to get to our goal of Torr As shown in figure 4-18

(4) Connect the convectron to the system as shown in figure 4-19

Fig 4-18 checking for leaks using alcohol

Fig 4-19 Convectron attached to System

90

(5) Attach the clamps of the Multimeter to the bottom of the chamber as shown in figure 4-20

(6) Place the Quartz crystal in place

(7) Close tight vacuum chamber

(8) Connect all electrical appliances to power source

Fig 4-20 Multimeter Connections

2 Starting up the System

(1) We turn on all the devices as such Check all systems are ready to function Reset all values

that might be left over from previous tests

(2) Start the thickness monitor and set all values for this experiment In our case we got to testing

the system but not actual coating So we used the simulation mode of the thickness monitor as

shown in figure 4-21

Fig 4-21 Simulation Mode

91

(3) Start the turbo pump Make sure the lid on the vacuum chamber is tightly closed

(4) Start convectron and record initial pressure

(5) Start Multimeter and record initial current

3 Coating Process

(1) If we have the deposition material inside the filament boat the power source for the high

current must be started as well

(2) Record all initial values for thickness current pressure

(3) For an ideal experiment we need a thickness of around 101 nm a pressure of Torr and

a current of 300 A

44 Results

From previous experiments we have shown that we can turn a LED into a laser by means of AR

Coating In figure 4-22 shown below we can compare the actual results of a Diode before and after AR

coating From the blue line we can see that when the diode is at a current of 15mA its light will change

from LED to laser and if we look at the red line its critical current is around 30 to 35 mA

Fig 4-22 AR Coating Comparison for Laser Diodes

This means that the light emitted is not as strong as if the diode had been coated because inside the

chamber there must be some excitation first so the reflectivity of both sides inside the diode must be high

So because of the coating in one of the sides we have opened a door and let the light come out so the

critical current is risen as such and will be higher value than that of before the coating

92

In the following figures we can see the difference between before and after coating in a material The

thickness is around 1016 nm for this material

Fig 4-23 Before Coating

Fig 4-24 After Coating

93

Chapter 5 CONCLUSIONS AND RECOMMENDATIONS

51 Conclusions

For the first part of this independent study taking into consideration the data that came out of our

research and that sent by the provider we can say

1 SUM 23 after heat treatment will unexpectedly develop cracking in the middle of the tensile

testing process and suddenly break

2 Itrsquos possible that in the process of heat treatment to the SUM 23 material the treatment was not

uniform and this will create a pre-loaded moment force on one side that pushes on the other side

of the specimen resulting in material deformation

3 In the process of attaching the strain gauges to the materials it is very easy to make errors due to

poor adhesion or sudden removal in the tensile testing process

For our second part of the independent study the following can be made

1 At the beginning of this independent study we had no idea what Bose-Einstein Condensate was

or what was its purpose After much literature we finally comprehended the basic principles to

put into practice for our research

2 Our systemrsquos basic working principles and equipmentrsquos complexity are a little difficult to grasp

but hopefully we were able to understand enough of it

3 Theoretically from relation between the power and current we can know the advantages and

disadvantages of AR Coating

4 We were able to assemble the system and run test on its functions Even though we were able to

do this there is still much more work left to do with this system

52 Recommendations

For the Tensile Testing the following can be said

1 Ask the provider to check on the process of heat treatment on the SUM 23 material and give

them the information we have gathered through our test so they can correct for the mechanical

properties found if any change is needed

2 To avoid the problem of the inaccuracy of the poor adhesion of strain gauges we can attach

multiple strain gauges to the same one specimen so as to correlate data and improve our results

For the AR Coating the following can be said

1 We need to make sure that there are no physical defects on the main body of the chamber so as to

achieve maximum efficiency in the vacuum process If there was then the vacuum will arrive to

certain point and then start to decrease

2 It would be preferable to add some sort of visual aid that will allow the user to check the inside of

the chamber without actually opening it This will help us determine at what times we should

manipulate the current to better evaporate the substrate

94

REFERENCES

[1] A L Window Strain Gauge Technology Elsevier Applied Science London and New York 2nd

Edition 1992

[2] CC Perry and HR Lissner Strain Gauge Primer McGraw-Hill Book Co Inc New York 1955

[3] James W Dally William F Riley McGraw-Hill 1978

[4] University of Colorado Boulder BEC - What is it and where did the idea come from

httpwwwcoloradoeduphysics2000becwhat_is_ithtml

[5] Ultraslow Light amp Bose-Einstein Condensates Two-way Control with Coherent Light amp Atom

Fields Harvard Hau Lab Dr Lene Vestergaard Hau Optics amp Photonics News 16 1995

[6] The Art of Taming Light Ultra-slow and Stopped Light Harvard Hau Lab Dr Lene

Vestergaard Hau Europhysics News 2004

[7] Nonlinear Optics Shocking Superfluids Harvard Hau Lab Dr Lene Vestergaard Hau Nature

Physics 2007

[8] Model P3 Strain Indicator and Recorder Instruction Manual Vishay Micro-Measurements 2005

[9] Granville-Phillips Series 375 Convectron Vacuum Gauge Controller Instruction Manual Brooks

Automation 2008

[10] Effect of Film Thickness on the Validity of the Sauerbrey Equation for Hydrated Polyelectrolyte

Films Vogt Lin Wu White 2004

[11] Quartz Crystal Microbalance Study of DNA Immobilization and Hybridization for DNA Sensor

Development Chang Zhao 2008

[12] Installation of Strain Gages with SR-4 PrecoatAdhesive Vishay Micro-Measurements 2005

[13] Strain Gauge Measurement ndash A Tutorial National Instruments 1998

[14] Correlation between Vickers Hardness Number and Yield Stress of Cold-Formed Products

Yavuz Tekkaya

[15] httpsenwikipediaorg

Page 45: PC Hinge Materials Testing and AR Laser Diode Coating

45

323 Strain Gauge

The strain gaugersquos main basic principle is to use a resistancersquos characteristics to measure the strain

The inside connections of the strain indicator are shown in figure 3-5

Fig 3-5 Inner Connections

As shown above this is a quarter-bridge connection We connect equal-length 3 wires to the 2

connections allowed by the strain gauge wire 1 and 3 can be used to cancel out the effects of temperature

to the resistance and because of the addition of wires 1 and 3 wire 2 can directly measure the experiment

results from the strain gauge and therefore the strain developed with no influence of temperature

If there were no two measuring leads then the relations will be

R 4 =R g +2R L

Where Rg is the Strain Gauge Value and RL is the wire resistance then

4

4

R

R=

Lg

g

RR

R

2

=

gL

gg

RR

RR

21

amp

4

4

R

R=

g

g

R

R(1- L)

Where L is the Signal Loss Factor and so

L =gL

gL

RR

RR

21

2

g

L

R

2R if

g

L

R

2Rltlt1

46

(Actual Value R g =120R L =08g

L

R

2Ris always much smaller than 1)

R 4 =R g +2R LR 2 =R 3 =rR gR 1 =R g 32 RR =0

V 0 =V 2)1( r

r

(

4

4

R

R-

1

1

R

R)

The first term describes loss attenuation effects second term describes loss of balancing capabilities

effects

V 0 =V 2)1( r

r

[

)2

(Lg

g

RR

R

+

T

Lg

g

RR

R

)

2( + T

Lg

L

RR

R

)

2

2( -(

g

g

R

R) T ]

The first term describes loss attenuation effects and loss of balancing capabilities effects the second

third and fourth terms describe the temperature effects on the wire

For the three-wire method we have

L =gL

gL

RR

RR

1

g

L

R

R if

g

L

R

Rltlt1

V 0 =V 2)1( r

r

[

)(Lg

g

RR

R

+

T

Lg

g

RR

R

)( + T

Lg

L

RR

R

)

2( -

T

Lg

g

RR

R

)( - T

Lg

L

RR

R

)

2( ]

V 0 = V2)1( r

r

)(

Lg

g

RR

R

In the last four terms inside parenthesis we can see the effects of temperature being cancelled out and the

effect on first term is not great so this is the reason why in our research we use three wires

47

324 Specimen Measurements

The tensile specimens used in this research are compliant of ASTM E8 Tensile parameters as shown

in figure 3-6

Fig 3-6 Tensile Specimen

Diameter

D(mm)

Gauge

Length

G(mm)

Smallest

Arc

Radius

R(mm)

Shortest

Area

A(mm)

Total

Length

L(mm)

Clamping

Area

Length

B(mm)

Clamping

Area

Diameter

C(mm)

Bar 125 02 625 01 gt10 gt75 ~ 145 ~ 35 20

Table 3-3 Specifications for Round Bar

33 Experiment Procedure

1 Attaching the Strain Gauge to the Tensile Specimen

(1) Prepare 1 ASTM E8 compliant tensile specimen round bar as shown in figure 3-7

(2) Prepare Strain Gauge as those described in table 3-4

(3) Prepare other consumables and adhesive agent such as epoxy adhesive or

cyanoacrylate adhesive as shown in figure 3-8

48

Fig 3-7 Actual Tensile Specimen

Fig 3-8 Other Materials Used (Such as Alcohol gauze transparent tape adhesive)

Gage Type

EA-06-120LZ-120E

Resistance in ohms at 24∘C

1200plusmn03

Gage Factor at 24∘C

2075plusmn05

Transverse Sensitivity at 24∘C

(+07plusmn02)

Table 3-4 Specifications for Strain Gauge

2 Attaching Strain Gauge

As shown in following figures we shall explain the attachment of the strain gauge

(1) Use sand paper and a rasp to clean thoroughly the surface where the strain gauge will be

attached to

49

(a)

(2) Use alcohol to wash the surface where the strain gauge will be attached and use gauze to rub

it off

(b)

(3) Find a clean surface and clean it with alcohol and gauze

(c)

(4) Place the strain gauge in the clean surface Use a piece of transparent tape on top of the strain

gauge after securely placed rip it off the surface carefully

50

(d)

(5) Use a piece of white paper to mark the place where the strain gauge will be attached and in

this way we can make sure that the strain gauge will be placed as horizontally and vertically

correct as possible

(e)

(6) In the place where we had our mark place the strain gauge

(f)

(7) Carefully lift one side of the tape and apply some of the adhesive agent to both the strain

gauge and specimenrsquos surface

(g)

51

(8) We need to make sure that the gauge and the specimen will be firmly attached so we gently

apply pressure with our thumb

(h)

(9) After the adhesive is fully dry we can carefully rip off the tape

(i)

(10) We need to do the whole process twice one for the horizontally placed strain gauge and one

for the vertically placed strain gauge

52

(j)

(11) We now proceed to solder the wires to the strain gauge

(k)

(12) After soldering we use a Volt Multimeter to measure that there is no contact between wires

If there is none then the specimen is ready for testing

(l)

(13) We now need to measure a 5cm distance and mark it to check and compare the elongation

before and after the tensile testing

(m)

53

Fig 3-9 Specimen-Strain Gauge Process

3 Tensile Test

(1) Enter the computer application that controls the tensile testing machine

(2) Turn on the tensile testing machine main switch

(3) Adjust the hydraulic pump to go back to its original position

(4) Bring the lowering motor down to a distance enough so as to attach the tensile specimen to the

system open the clamps and secure the specimen

(a)

(5) Connect all the necessary wires to the strain indicator equipment

54

(b)

(6) Start the ascending motor and wait for the expansion

(c)

Fig 3-10 Specimen-Tensile Testing Process

4 Start the Test

(1) Enter the software application and enter some variables needed for the experiment in the

specific screen

(2) Go back to the main screen and press the [測試] (measure) button to start the test and auto

recording in the software

(3) After the specimen breaks the mechanical device will automatically stop and ask the user to

enter the total displacement We take out the specimen from the testing machine and adjust the

machinersquos position back to its original position

(4) Save the results information

(5) Record the results from the strain indicator

34 Results

From this experiment we can get the Poissonrsquos Ratio Youngrsquos Modulus and Yield Strength etc and

because of the slippage phenomenon in the clamp at the moment of the test then the Elastic Limit will

display some yield phenomena So omit any undesirable results we just take the Yield portion of the

results as reference

In the process of the experiment the most important part to attend to is the attaching of the strain

gauge because the gaugersquos purpose is to measure the strain developed during the test and this strain

might be very small If the gaugersquos angle change during the test ie is not well attached this will affect

the accuracy of the measurements of Poissonrsquos ratio and Youngrsquos modulus

55

The materials provided by the manufacturer are SUM 23 and SUM 43 steel round bars and these two

types of materials have been through different heat treatment processes so they can be sub-divided

further into untreated material heat-treated material and black surface heat treated material for the two

materials with heat treatment the treatment process and finished are different In the end we only have

the mechanical properties that were calculated after our research of these materials

All of the specifications are identical to those shown in figure 3-6

341 SUM 23

Fig 3-11 SUM 23 Untreated Material

Number 7 10

Hardness(HRB) 74 75

Yield Stress (MPa) 448 440

Tensile Strength (MPa) 544 560

Poissonrsquos Ratio 029 027

Youngrsquos Modulus (GPa) 203 210

Cut-off Area Shrinking () 42 41

Elongation () 1125 1011

Table 3-5 Mechanical Properties of SUM 23 Untreated

56

Stress-Strain Diagram

(a)

(b)

57

Fig 3-12 Stress-Strain Diagrams for (a) 7 Round Bar and (b) 10 Round Bar

Cut-Off Area

(a)

(b)

Fig 3-13 Cut-Off Area of (a) 7 Round Bar and (b) 10 Round Bar

58

SUM 23 Nickel Round Bar

Fig 3-14 SUM 23 Nickel Material

Number 1 2 3 4

Hardness(HRB) 48 50 49 48

Yield Stress (MPa) 370 370 380 400

Tensile Strength (MPa) 455 451 450 450

Poissonrsquos Ratio 028 046 029 026

Youngrsquos Modulus (GPa) 243 303 246 206

Cut-off Area Shrinking () 803 803 726 601

Elongation () 566 65 602 647

Table 3-6 Mechanical Properties of SUM 23 Nickel

59

Stress-Strain Diagram

(a)

60

(b)

(c)

(d)

61

Fig 3-15 Stress-Strain Diagrams for (a) 1 Round Bar (b) 2 Round Bar (c) 3 Round Bar and (d)

4 Round Bar

Cut-Off Area

(a)

(b)

62

(c)

(d)

Fig 3-16 Cut-Off Area of (a) 1 Round Bar (b) 2 Round Bar (c) 3 Round Bar and (d) 4 Round

Bar

63

SUM 23 Black Surface Round Bar

Fig 3-17 SUM 23 Black Surface Material

Number 1 2 3

Hardness(HRB) 51 50 51

Yield Stress (MPa) 378 371 369

Tensile Strength (MPa) 467 465 464

Poissonrsquos Ratio 03 016 04

Youngrsquos Modulus (GPa) 215 266 266

Cut-off Area Shrinking () 986 94 848

Elongation () 748 805 761

Table 3-7 Mechanical Properties of SUM 23 Black Surface Material

64

Stress-Strain Diagram

(a)

(b)

65

(c)

Fig 3-18 Stress-Strain Diagrams for (a) 1 Round Bar 2 Round Bar and (c) 3 Round Bar

Cut-Off Surface

(a)

66

(b)

(c)

Fig 3-19 Cut-Off Surface of (a) 1 Round Bar 2 Round Bar and (c) 3 Round Bar

67

342 SUM 43

Fig 3-20 Untreated SUM 43 Untreated Material

Number 1 5

Hardness(HRB) 76 75

Yield Stress (MPa) 572 594

Tensile Strength (MPa) 743 785

Poissonrsquos Ratio 027 029

Youngrsquos Modulus (GPa) 200 202

Cut-off Area Shrinking () 338 2944

Elongation () 857 894

Table 3-8 Mechanical Properties of SUM 43 Untreated

68

Stress-Strain Diagrams

(a)

(b)

Fig 3-21 Stress-Strain Diagrams for SUM 43 (a) 1 Round Bar and (b) 5 Round Bar

69

Cut-Off Area

(a)

(b)

Fig 3-22 Cut-Off Area of SUM 43 (a) 1 Round Bar and (b) 5 Round Bar

70

SUM 43 Nickel Round Bar

Fig 3-23 SUM 43 Nickel Material

Number 4 5

Hardness(HRB) 51 50

Yield Stress (MPa) 1580 1544

Tensile Strength (MPa) 1639 1625

Poissonrsquos Ratio 03 028

Youngrsquos Modulus (GPa) 194 201

Cut-off Area Shrinking () 1697 137

Elongation () 376 265

Table 3-9 Mechanical Properties of SUM 43 Nickel

71

Stress-Strain Diagrams

(a)

(b)

Fig 3-24 Stress-Strain Diagrams for (a) 4 Round Bar and (b) 5 Round Bar

72

Cut-Off Area

(a)

(b)

Fig 3-25 Cut-Off Area of (a) 4 Round Bar and (b) 5 Round Bar

73

SUM 43 Black Surface Material

Fig 3-26 SUM 43 Black Surface Material

Number 3 5

Hardness(HRB) 56 56

Yield Stress (MPa) 1416 1361

Tensile Strength (MPa) 1591 1402

Poissonrsquos Ratio 029 031

Youngrsquos Modulus (GPa) 200 202

Cut-off Area Shrinking () 139 124

Elongation () 24 24

Table 3-10 Mechanical Properties of SUM 43 Black Surface Material

74

Stress-Strain Diagrams

0 2 4 6 8 10 12 14

-200

0

200

400

600

800

1000

1200

1400

1600

1800

應力 (MPa)

應變()

(a)

0 2 4 6 8 10

-200

0

200

400

600

800

1000

1200

1400

1600

應力

(MPa)

位移 ()

(b)

Fig 3-27 Stress-Strain Diagrams for (a) 3 Round Bar and (b) 5 Round Bar

(Note These curves were formulated using Visual Solutions Inc VisSim Software)

75

Cut-Off Area

(a)

(b)

Fig 3-28 Cut-Off Area of (a) 3 Round Bar and (b) 5 Round Bar

76

The force value (N) was retrieved from the Universal Testing Machine

The Poissonrsquos Ratio (ε) is calculated as

ε =

the values for the Poissonrsquos Ratio are in average around 0297

The Youngrsquos Modulus (E) is calculated as

E =

Where

Stress =

Cross-sectional Area =

where D is the Diameter

The value for D was in average around 1258 mm

The values shown by the computer because there is Slippage phenomena between the Clamp and the

specimen will not be taken into consideration for the elongation strain and Youngrsquos modulus and we will

refer to the values that we have meticulously calculated

77

Chapter 4 AR COATING IN DEPTH

41 Experimentrsquos Purpose and Principles

By means of a vacuum chamber and several other instruments we intend to apply Anti-Reflective

Coating using deposition process to a laser diode and in this way reduce its refraction so as to make it

lose less light in the process of amplification and we can control certain wavelengths we want produced

for certain desired applications in our case we are attempting to re-create a Bose-Einstein Condensate

An optimal BEC apparatus is shown in figure 4-1

Fig 4-1 BEC Apparatus

The main point of this experiment is to build a vacuum chamber system attach all the instrumentation

needed (Vacuum pump deposition meter and voltmeter) and use it to apply AR coating to a laser diode

After we have accomplished the AR coating other team will be in charge of designing the BEC apparatus

and use the results of our research

78

42 Experimentrsquos Equipment

421 Vacuum Chamber

For this research we designed a vacuum chamber whose main body is shown in figure 4-2 Its

dimensions are

Width 240 mm

Length 240 mm

Height 200 mm

Outer Diameter 4 in

Inner Diameter 15 in

Fig 4-2 Vacuum Chamber Main Body

The chamber is made up of 6 pass ways pass way A is the connection with the Laser Deposition

Equipment pass way B is the connection with the Turbo Pump and pass way C is for the connection with

the Deposition Source

A

C

B

79

Pass way C is for the deposition source as mentioned above This is a system where a thermal

resistance is heated by passing a high current through it which heats up a filament boat (made of tungsten)

where the material to be evaporated is place We control the temperature as such that the material will

evaporate and the heat will not cause the filament boat to crack

Because P = Isup2 R (where P is power I is current and R is resistance) to avoid the current to flow

where it is not desired we decided that the material for the Thermocouple shown in figure 4-3 should be

Copper ᴓ 63 mm We choose it that way because Copper has very good heat dissipation characteristics

and the resistance value is low It can reduce the value of the current enough to make the thermocouple to

create heat

Fig 4-3 Thermocouple

To the thermocouple we attach the tungsten filament boat We need to take notice of materials to be

used in this design because when using high current the tungsten filament boar will heat up and so the

material must be able to keep up with the heating potential of tungsten and has a low coefficient of heat

dissipation to avoid the tungsten to fail when heating up and therefore not evaporating Considering all

this we decide to use Stainless Steel

Because this clamp will be assembled inside the chamber after many revisions it was determined it

will have the shape shown in figure 4-4

Fig 4-4 Filament Boat Clamp Design

80

For the tungsten filament boat we bought the product from a distributor The dimensions are

Length 100 mm

Width 10 mm

Height 1 mm

Our thermocouple is 15 in but the pass way C is 4 in so we need to attach a Flange that connects

15in to 4in Because these specifications are quite difficult to achieve by Milling we had to use

electrical wire cutting

For the laser clamping system where the laser that is going to be AR coated will be placed will be

connected to pass way A the assembly is shown in figure 4-5 below

Fig 4-5 Cover Assembly

For this design we used an O-ring instead of a gasket so as to save time The design of the assembly

where the laser will be placed is shown in figure 4-6

Fig 4-6 Upper Cover Inner Assembly

D

E

F

81

Point D is the plate in the assembly where the laser diode will be fixed Because of the easy

processing we decide to use Aluminum and it is screwed to the top cover Point E is the connection for

the Quartz crystal resonator and it is designed in the same as point F in this way the results of the quartz

microbalance system will be more accurate in real time Point F is the final resting place for the laser

diode We use a Thor Labs Base with dimensions of ᴓ 9mm and ᴓ 56mm for two different size laser

diodes It just needs to be plugged in for easy installation

From figure 4-6 we know that the system needs signal system connections and because of the

change in temperature inside the chamber this could affect the functioning of the quartz microbalance so

we also need to install water tubes for cooling This is shown in figure 4-7 below

Fig 4-7 Diagram of Upper Cover Connections

In figure 4-8 we show the Feed through connections and their functions

Fig 4-8 Feed through Diagram

82

1 SQM-160 wire 5 Laser Connection 1 (Vin)

2 SQM-160 (G) 6 Laser Connection 2 (G)

3 K-Type-1 7 Laser Connection 3 (PD)

4 K-Type-2 8 Not In Use

The fully assembled chamber is shown in figure 4-9

Fig 4-9 Fully Assembled Chamber

422 Quartz Crystal Microbalance

For measuring the deposition on our target for coating we used the Inficon SQM-160 RateThickness

Monitor It is an easy to use instrument for measuring many types of thin-film coatings as shown in

figure 4-10

(a) Front Panel (b) Back Panel

Fig 4-10 Inficon SQM-160

83

Table 4-1 shows the technical specifications for this equipment

Number of sensors 2 Standard 4 additional optional

Sensor Frequency Range 40 MHz ~ 60 MHz

Reference Frequency Accuracy 002

Thickness Display Resolution 1 Aring

Thickness Resolution 015 Aring (Std) 0037 Aring (Hi Res)

Density of Stored Films 05-9999 gmcc

Tooling 10-399

Z-Factor 010-1000

Final Thickness 0000-9999k Aring

Measurement Period 15 to 2 sec

Simulation Mode Yes

Frequency Mode Yes

Rate Resolution 011 Arings

Dual Crystal Yes

Etch Mode Yes

Crystal Tooling 10-399

Crystal Fail Min Max 40 to 60 MHz 41 to 61 MHz

Power 100-120 200-240~plusmn10 nominal 20W

Operation Environment 0degC ~ 50degC

0 ~ 80 RH non-condensing

0 ~ 2000 meters

Class 1 Equipment

Pollution Degree 2

Rack Dimensions 885mm x 2127mm x 1969mm

Weight 27 kg

Table 4-1 Inficon SQM-160 RateThickness Monitor Specs

84

To the SQM-160 we need to connect an Oscillator We use the Sigma Instruments Remote Oscillator

Ser No 2 268 as shown in figure 4-11

Fig 4-11 Sigma Instruments Remote Oscillator

The connections diagram is shown in figure 4-12

Fig 4-12 SQM-160 Connections Diagram

85

423 Turbo Pump

For our experiments we used the Pfeiffer TCP 015 Electronic Drive Unit shown below in figure 4-13

Table 4-2 shows the technical specifications for this equipment

(a) Front Panel (b) Back Panel

Fig 4-13 Pfeiffer TCP 015 Electronic Drive

Connection Voltage (100V) 90-112

Mains Frequency 5060 Hz

Start-up Current 22 A

Nominal Frequency 1500 Hz

Rotation Speed 10V = 1500Hz plusmn2

Analog Output Current 10 V = 25 A plusmn 5

Rotation Speed Switchpoint 750 Hz

Works Setting 8 min

Permissible Ambient Temperature 0degC ~ 40degC

Dimensions Front Panel 1285mm x 1063mm

Insertion Length 227mm

Weight 27 Kg

Table 4-2 Pfeiffer TCP 015 Electronic Drive Specs

86

The connections diagram is shown in figure 4-14

Fig 4-14Connections Diagram for Pfeiffer TCP 015

To measure the pressure inside the chamber we use the Granville Phillips 375 Convectron Vacuum

Pressure Controller shown in figure 4-15

(a) Front Panel (b) Back Panel

Fig 4-15 Granville Phillips 375 Convectron

87

Its dimensions are shown in figure 4-16

Fig 4-16 Dimensions of Convectron

Table 4-3 shows the technical specifications for this equipment

Table 4-3 Granville Phillips 375 Convectron Vacuum Pressure Controller Specs

88

424 Multimeter

For our experiment we used the Keithley 2000 Digital Multimeter as shown in figure 4-17

(a) Front Panel (b) Back Panel

Fig 4-17 Keithley Model 2000 6-12-Digit Digital Multimeter

Its technical specifications are shown in table 4-4

Table 4-4 Keithley Model 2000 6-12-Digit Digital Multimeter Specs

89

43 Experiment Procedure

1 Connecting together the equipment and the chamber

(1) We first connect the resonator to the thickness monitor and connect the other side to the

chamber

(2) We now connect the flexible tubes to the turbo pump on one side and to the chamber on the

other

(3) We need to check that tubes are tightly connected to avoid any leaks in the vacuum pumping

process which will not allow us to get to our goal of Torr As shown in figure 4-18

(4) Connect the convectron to the system as shown in figure 4-19

Fig 4-18 checking for leaks using alcohol

Fig 4-19 Convectron attached to System

90

(5) Attach the clamps of the Multimeter to the bottom of the chamber as shown in figure 4-20

(6) Place the Quartz crystal in place

(7) Close tight vacuum chamber

(8) Connect all electrical appliances to power source

Fig 4-20 Multimeter Connections

2 Starting up the System

(1) We turn on all the devices as such Check all systems are ready to function Reset all values

that might be left over from previous tests

(2) Start the thickness monitor and set all values for this experiment In our case we got to testing

the system but not actual coating So we used the simulation mode of the thickness monitor as

shown in figure 4-21

Fig 4-21 Simulation Mode

91

(3) Start the turbo pump Make sure the lid on the vacuum chamber is tightly closed

(4) Start convectron and record initial pressure

(5) Start Multimeter and record initial current

3 Coating Process

(1) If we have the deposition material inside the filament boat the power source for the high

current must be started as well

(2) Record all initial values for thickness current pressure

(3) For an ideal experiment we need a thickness of around 101 nm a pressure of Torr and

a current of 300 A

44 Results

From previous experiments we have shown that we can turn a LED into a laser by means of AR

Coating In figure 4-22 shown below we can compare the actual results of a Diode before and after AR

coating From the blue line we can see that when the diode is at a current of 15mA its light will change

from LED to laser and if we look at the red line its critical current is around 30 to 35 mA

Fig 4-22 AR Coating Comparison for Laser Diodes

This means that the light emitted is not as strong as if the diode had been coated because inside the

chamber there must be some excitation first so the reflectivity of both sides inside the diode must be high

So because of the coating in one of the sides we have opened a door and let the light come out so the

critical current is risen as such and will be higher value than that of before the coating

92

In the following figures we can see the difference between before and after coating in a material The

thickness is around 1016 nm for this material

Fig 4-23 Before Coating

Fig 4-24 After Coating

93

Chapter 5 CONCLUSIONS AND RECOMMENDATIONS

51 Conclusions

For the first part of this independent study taking into consideration the data that came out of our

research and that sent by the provider we can say

1 SUM 23 after heat treatment will unexpectedly develop cracking in the middle of the tensile

testing process and suddenly break

2 Itrsquos possible that in the process of heat treatment to the SUM 23 material the treatment was not

uniform and this will create a pre-loaded moment force on one side that pushes on the other side

of the specimen resulting in material deformation

3 In the process of attaching the strain gauges to the materials it is very easy to make errors due to

poor adhesion or sudden removal in the tensile testing process

For our second part of the independent study the following can be made

1 At the beginning of this independent study we had no idea what Bose-Einstein Condensate was

or what was its purpose After much literature we finally comprehended the basic principles to

put into practice for our research

2 Our systemrsquos basic working principles and equipmentrsquos complexity are a little difficult to grasp

but hopefully we were able to understand enough of it

3 Theoretically from relation between the power and current we can know the advantages and

disadvantages of AR Coating

4 We were able to assemble the system and run test on its functions Even though we were able to

do this there is still much more work left to do with this system

52 Recommendations

For the Tensile Testing the following can be said

1 Ask the provider to check on the process of heat treatment on the SUM 23 material and give

them the information we have gathered through our test so they can correct for the mechanical

properties found if any change is needed

2 To avoid the problem of the inaccuracy of the poor adhesion of strain gauges we can attach

multiple strain gauges to the same one specimen so as to correlate data and improve our results

For the AR Coating the following can be said

1 We need to make sure that there are no physical defects on the main body of the chamber so as to

achieve maximum efficiency in the vacuum process If there was then the vacuum will arrive to

certain point and then start to decrease

2 It would be preferable to add some sort of visual aid that will allow the user to check the inside of

the chamber without actually opening it This will help us determine at what times we should

manipulate the current to better evaporate the substrate

94

REFERENCES

[1] A L Window Strain Gauge Technology Elsevier Applied Science London and New York 2nd

Edition 1992

[2] CC Perry and HR Lissner Strain Gauge Primer McGraw-Hill Book Co Inc New York 1955

[3] James W Dally William F Riley McGraw-Hill 1978

[4] University of Colorado Boulder BEC - What is it and where did the idea come from

httpwwwcoloradoeduphysics2000becwhat_is_ithtml

[5] Ultraslow Light amp Bose-Einstein Condensates Two-way Control with Coherent Light amp Atom

Fields Harvard Hau Lab Dr Lene Vestergaard Hau Optics amp Photonics News 16 1995

[6] The Art of Taming Light Ultra-slow and Stopped Light Harvard Hau Lab Dr Lene

Vestergaard Hau Europhysics News 2004

[7] Nonlinear Optics Shocking Superfluids Harvard Hau Lab Dr Lene Vestergaard Hau Nature

Physics 2007

[8] Model P3 Strain Indicator and Recorder Instruction Manual Vishay Micro-Measurements 2005

[9] Granville-Phillips Series 375 Convectron Vacuum Gauge Controller Instruction Manual Brooks

Automation 2008

[10] Effect of Film Thickness on the Validity of the Sauerbrey Equation for Hydrated Polyelectrolyte

Films Vogt Lin Wu White 2004

[11] Quartz Crystal Microbalance Study of DNA Immobilization and Hybridization for DNA Sensor

Development Chang Zhao 2008

[12] Installation of Strain Gages with SR-4 PrecoatAdhesive Vishay Micro-Measurements 2005

[13] Strain Gauge Measurement ndash A Tutorial National Instruments 1998

[14] Correlation between Vickers Hardness Number and Yield Stress of Cold-Formed Products

Yavuz Tekkaya

[15] httpsenwikipediaorg

Page 46: PC Hinge Materials Testing and AR Laser Diode Coating

46

(Actual Value R g =120R L =08g

L

R

2Ris always much smaller than 1)

R 4 =R g +2R LR 2 =R 3 =rR gR 1 =R g 32 RR =0

V 0 =V 2)1( r

r

(

4

4

R

R-

1

1

R

R)

The first term describes loss attenuation effects second term describes loss of balancing capabilities

effects

V 0 =V 2)1( r

r

[

)2

(Lg

g

RR

R

+

T

Lg

g

RR

R

)

2( + T

Lg

L

RR

R

)

2

2( -(

g

g

R

R) T ]

The first term describes loss attenuation effects and loss of balancing capabilities effects the second

third and fourth terms describe the temperature effects on the wire

For the three-wire method we have

L =gL

gL

RR

RR

1

g

L

R

R if

g

L

R

Rltlt1

V 0 =V 2)1( r

r

[

)(Lg

g

RR

R

+

T

Lg

g

RR

R

)( + T

Lg

L

RR

R

)

2( -

T

Lg

g

RR

R

)( - T

Lg

L

RR

R

)

2( ]

V 0 = V2)1( r

r

)(

Lg

g

RR

R

In the last four terms inside parenthesis we can see the effects of temperature being cancelled out and the

effect on first term is not great so this is the reason why in our research we use three wires

47

324 Specimen Measurements

The tensile specimens used in this research are compliant of ASTM E8 Tensile parameters as shown

in figure 3-6

Fig 3-6 Tensile Specimen

Diameter

D(mm)

Gauge

Length

G(mm)

Smallest

Arc

Radius

R(mm)

Shortest

Area

A(mm)

Total

Length

L(mm)

Clamping

Area

Length

B(mm)

Clamping

Area

Diameter

C(mm)

Bar 125 02 625 01 gt10 gt75 ~ 145 ~ 35 20

Table 3-3 Specifications for Round Bar

33 Experiment Procedure

1 Attaching the Strain Gauge to the Tensile Specimen

(1) Prepare 1 ASTM E8 compliant tensile specimen round bar as shown in figure 3-7

(2) Prepare Strain Gauge as those described in table 3-4

(3) Prepare other consumables and adhesive agent such as epoxy adhesive or

cyanoacrylate adhesive as shown in figure 3-8

48

Fig 3-7 Actual Tensile Specimen

Fig 3-8 Other Materials Used (Such as Alcohol gauze transparent tape adhesive)

Gage Type

EA-06-120LZ-120E

Resistance in ohms at 24∘C

1200plusmn03

Gage Factor at 24∘C

2075plusmn05

Transverse Sensitivity at 24∘C

(+07plusmn02)

Table 3-4 Specifications for Strain Gauge

2 Attaching Strain Gauge

As shown in following figures we shall explain the attachment of the strain gauge

(1) Use sand paper and a rasp to clean thoroughly the surface where the strain gauge will be

attached to

49

(a)

(2) Use alcohol to wash the surface where the strain gauge will be attached and use gauze to rub

it off

(b)

(3) Find a clean surface and clean it with alcohol and gauze

(c)

(4) Place the strain gauge in the clean surface Use a piece of transparent tape on top of the strain

gauge after securely placed rip it off the surface carefully

50

(d)

(5) Use a piece of white paper to mark the place where the strain gauge will be attached and in

this way we can make sure that the strain gauge will be placed as horizontally and vertically

correct as possible

(e)

(6) In the place where we had our mark place the strain gauge

(f)

(7) Carefully lift one side of the tape and apply some of the adhesive agent to both the strain

gauge and specimenrsquos surface

(g)

51

(8) We need to make sure that the gauge and the specimen will be firmly attached so we gently

apply pressure with our thumb

(h)

(9) After the adhesive is fully dry we can carefully rip off the tape

(i)

(10) We need to do the whole process twice one for the horizontally placed strain gauge and one

for the vertically placed strain gauge

52

(j)

(11) We now proceed to solder the wires to the strain gauge

(k)

(12) After soldering we use a Volt Multimeter to measure that there is no contact between wires

If there is none then the specimen is ready for testing

(l)

(13) We now need to measure a 5cm distance and mark it to check and compare the elongation

before and after the tensile testing

(m)

53

Fig 3-9 Specimen-Strain Gauge Process

3 Tensile Test

(1) Enter the computer application that controls the tensile testing machine

(2) Turn on the tensile testing machine main switch

(3) Adjust the hydraulic pump to go back to its original position

(4) Bring the lowering motor down to a distance enough so as to attach the tensile specimen to the

system open the clamps and secure the specimen

(a)

(5) Connect all the necessary wires to the strain indicator equipment

54

(b)

(6) Start the ascending motor and wait for the expansion

(c)

Fig 3-10 Specimen-Tensile Testing Process

4 Start the Test

(1) Enter the software application and enter some variables needed for the experiment in the

specific screen

(2) Go back to the main screen and press the [測試] (measure) button to start the test and auto

recording in the software

(3) After the specimen breaks the mechanical device will automatically stop and ask the user to

enter the total displacement We take out the specimen from the testing machine and adjust the

machinersquos position back to its original position

(4) Save the results information

(5) Record the results from the strain indicator

34 Results

From this experiment we can get the Poissonrsquos Ratio Youngrsquos Modulus and Yield Strength etc and

because of the slippage phenomenon in the clamp at the moment of the test then the Elastic Limit will

display some yield phenomena So omit any undesirable results we just take the Yield portion of the

results as reference

In the process of the experiment the most important part to attend to is the attaching of the strain

gauge because the gaugersquos purpose is to measure the strain developed during the test and this strain

might be very small If the gaugersquos angle change during the test ie is not well attached this will affect

the accuracy of the measurements of Poissonrsquos ratio and Youngrsquos modulus

55

The materials provided by the manufacturer are SUM 23 and SUM 43 steel round bars and these two

types of materials have been through different heat treatment processes so they can be sub-divided

further into untreated material heat-treated material and black surface heat treated material for the two

materials with heat treatment the treatment process and finished are different In the end we only have

the mechanical properties that were calculated after our research of these materials

All of the specifications are identical to those shown in figure 3-6

341 SUM 23

Fig 3-11 SUM 23 Untreated Material

Number 7 10

Hardness(HRB) 74 75

Yield Stress (MPa) 448 440

Tensile Strength (MPa) 544 560

Poissonrsquos Ratio 029 027

Youngrsquos Modulus (GPa) 203 210

Cut-off Area Shrinking () 42 41

Elongation () 1125 1011

Table 3-5 Mechanical Properties of SUM 23 Untreated

56

Stress-Strain Diagram

(a)

(b)

57

Fig 3-12 Stress-Strain Diagrams for (a) 7 Round Bar and (b) 10 Round Bar

Cut-Off Area

(a)

(b)

Fig 3-13 Cut-Off Area of (a) 7 Round Bar and (b) 10 Round Bar

58

SUM 23 Nickel Round Bar

Fig 3-14 SUM 23 Nickel Material

Number 1 2 3 4

Hardness(HRB) 48 50 49 48

Yield Stress (MPa) 370 370 380 400

Tensile Strength (MPa) 455 451 450 450

Poissonrsquos Ratio 028 046 029 026

Youngrsquos Modulus (GPa) 243 303 246 206

Cut-off Area Shrinking () 803 803 726 601

Elongation () 566 65 602 647

Table 3-6 Mechanical Properties of SUM 23 Nickel

59

Stress-Strain Diagram

(a)

60

(b)

(c)

(d)

61

Fig 3-15 Stress-Strain Diagrams for (a) 1 Round Bar (b) 2 Round Bar (c) 3 Round Bar and (d)

4 Round Bar

Cut-Off Area

(a)

(b)

62

(c)

(d)

Fig 3-16 Cut-Off Area of (a) 1 Round Bar (b) 2 Round Bar (c) 3 Round Bar and (d) 4 Round

Bar

63

SUM 23 Black Surface Round Bar

Fig 3-17 SUM 23 Black Surface Material

Number 1 2 3

Hardness(HRB) 51 50 51

Yield Stress (MPa) 378 371 369

Tensile Strength (MPa) 467 465 464

Poissonrsquos Ratio 03 016 04

Youngrsquos Modulus (GPa) 215 266 266

Cut-off Area Shrinking () 986 94 848

Elongation () 748 805 761

Table 3-7 Mechanical Properties of SUM 23 Black Surface Material

64

Stress-Strain Diagram

(a)

(b)

65

(c)

Fig 3-18 Stress-Strain Diagrams for (a) 1 Round Bar 2 Round Bar and (c) 3 Round Bar

Cut-Off Surface

(a)

66

(b)

(c)

Fig 3-19 Cut-Off Surface of (a) 1 Round Bar 2 Round Bar and (c) 3 Round Bar

67

342 SUM 43

Fig 3-20 Untreated SUM 43 Untreated Material

Number 1 5

Hardness(HRB) 76 75

Yield Stress (MPa) 572 594

Tensile Strength (MPa) 743 785

Poissonrsquos Ratio 027 029

Youngrsquos Modulus (GPa) 200 202

Cut-off Area Shrinking () 338 2944

Elongation () 857 894

Table 3-8 Mechanical Properties of SUM 43 Untreated

68

Stress-Strain Diagrams

(a)

(b)

Fig 3-21 Stress-Strain Diagrams for SUM 43 (a) 1 Round Bar and (b) 5 Round Bar

69

Cut-Off Area

(a)

(b)

Fig 3-22 Cut-Off Area of SUM 43 (a) 1 Round Bar and (b) 5 Round Bar

70

SUM 43 Nickel Round Bar

Fig 3-23 SUM 43 Nickel Material

Number 4 5

Hardness(HRB) 51 50

Yield Stress (MPa) 1580 1544

Tensile Strength (MPa) 1639 1625

Poissonrsquos Ratio 03 028

Youngrsquos Modulus (GPa) 194 201

Cut-off Area Shrinking () 1697 137

Elongation () 376 265

Table 3-9 Mechanical Properties of SUM 43 Nickel

71

Stress-Strain Diagrams

(a)

(b)

Fig 3-24 Stress-Strain Diagrams for (a) 4 Round Bar and (b) 5 Round Bar

72

Cut-Off Area

(a)

(b)

Fig 3-25 Cut-Off Area of (a) 4 Round Bar and (b) 5 Round Bar

73

SUM 43 Black Surface Material

Fig 3-26 SUM 43 Black Surface Material

Number 3 5

Hardness(HRB) 56 56

Yield Stress (MPa) 1416 1361

Tensile Strength (MPa) 1591 1402

Poissonrsquos Ratio 029 031

Youngrsquos Modulus (GPa) 200 202

Cut-off Area Shrinking () 139 124

Elongation () 24 24

Table 3-10 Mechanical Properties of SUM 43 Black Surface Material

74

Stress-Strain Diagrams

0 2 4 6 8 10 12 14

-200

0

200

400

600

800

1000

1200

1400

1600

1800

應力 (MPa)

應變()

(a)

0 2 4 6 8 10

-200

0

200

400

600

800

1000

1200

1400

1600

應力

(MPa)

位移 ()

(b)

Fig 3-27 Stress-Strain Diagrams for (a) 3 Round Bar and (b) 5 Round Bar

(Note These curves were formulated using Visual Solutions Inc VisSim Software)

75

Cut-Off Area

(a)

(b)

Fig 3-28 Cut-Off Area of (a) 3 Round Bar and (b) 5 Round Bar

76

The force value (N) was retrieved from the Universal Testing Machine

The Poissonrsquos Ratio (ε) is calculated as

ε =

the values for the Poissonrsquos Ratio are in average around 0297

The Youngrsquos Modulus (E) is calculated as

E =

Where

Stress =

Cross-sectional Area =

where D is the Diameter

The value for D was in average around 1258 mm

The values shown by the computer because there is Slippage phenomena between the Clamp and the

specimen will not be taken into consideration for the elongation strain and Youngrsquos modulus and we will

refer to the values that we have meticulously calculated

77

Chapter 4 AR COATING IN DEPTH

41 Experimentrsquos Purpose and Principles

By means of a vacuum chamber and several other instruments we intend to apply Anti-Reflective

Coating using deposition process to a laser diode and in this way reduce its refraction so as to make it

lose less light in the process of amplification and we can control certain wavelengths we want produced

for certain desired applications in our case we are attempting to re-create a Bose-Einstein Condensate

An optimal BEC apparatus is shown in figure 4-1

Fig 4-1 BEC Apparatus

The main point of this experiment is to build a vacuum chamber system attach all the instrumentation

needed (Vacuum pump deposition meter and voltmeter) and use it to apply AR coating to a laser diode

After we have accomplished the AR coating other team will be in charge of designing the BEC apparatus

and use the results of our research

78

42 Experimentrsquos Equipment

421 Vacuum Chamber

For this research we designed a vacuum chamber whose main body is shown in figure 4-2 Its

dimensions are

Width 240 mm

Length 240 mm

Height 200 mm

Outer Diameter 4 in

Inner Diameter 15 in

Fig 4-2 Vacuum Chamber Main Body

The chamber is made up of 6 pass ways pass way A is the connection with the Laser Deposition

Equipment pass way B is the connection with the Turbo Pump and pass way C is for the connection with

the Deposition Source

A

C

B

79

Pass way C is for the deposition source as mentioned above This is a system where a thermal

resistance is heated by passing a high current through it which heats up a filament boat (made of tungsten)

where the material to be evaporated is place We control the temperature as such that the material will

evaporate and the heat will not cause the filament boat to crack

Because P = Isup2 R (where P is power I is current and R is resistance) to avoid the current to flow

where it is not desired we decided that the material for the Thermocouple shown in figure 4-3 should be

Copper ᴓ 63 mm We choose it that way because Copper has very good heat dissipation characteristics

and the resistance value is low It can reduce the value of the current enough to make the thermocouple to

create heat

Fig 4-3 Thermocouple

To the thermocouple we attach the tungsten filament boat We need to take notice of materials to be

used in this design because when using high current the tungsten filament boar will heat up and so the

material must be able to keep up with the heating potential of tungsten and has a low coefficient of heat

dissipation to avoid the tungsten to fail when heating up and therefore not evaporating Considering all

this we decide to use Stainless Steel

Because this clamp will be assembled inside the chamber after many revisions it was determined it

will have the shape shown in figure 4-4

Fig 4-4 Filament Boat Clamp Design

80

For the tungsten filament boat we bought the product from a distributor The dimensions are

Length 100 mm

Width 10 mm

Height 1 mm

Our thermocouple is 15 in but the pass way C is 4 in so we need to attach a Flange that connects

15in to 4in Because these specifications are quite difficult to achieve by Milling we had to use

electrical wire cutting

For the laser clamping system where the laser that is going to be AR coated will be placed will be

connected to pass way A the assembly is shown in figure 4-5 below

Fig 4-5 Cover Assembly

For this design we used an O-ring instead of a gasket so as to save time The design of the assembly

where the laser will be placed is shown in figure 4-6

Fig 4-6 Upper Cover Inner Assembly

D

E

F

81

Point D is the plate in the assembly where the laser diode will be fixed Because of the easy

processing we decide to use Aluminum and it is screwed to the top cover Point E is the connection for

the Quartz crystal resonator and it is designed in the same as point F in this way the results of the quartz

microbalance system will be more accurate in real time Point F is the final resting place for the laser

diode We use a Thor Labs Base with dimensions of ᴓ 9mm and ᴓ 56mm for two different size laser

diodes It just needs to be plugged in for easy installation

From figure 4-6 we know that the system needs signal system connections and because of the

change in temperature inside the chamber this could affect the functioning of the quartz microbalance so

we also need to install water tubes for cooling This is shown in figure 4-7 below

Fig 4-7 Diagram of Upper Cover Connections

In figure 4-8 we show the Feed through connections and their functions

Fig 4-8 Feed through Diagram

82

1 SQM-160 wire 5 Laser Connection 1 (Vin)

2 SQM-160 (G) 6 Laser Connection 2 (G)

3 K-Type-1 7 Laser Connection 3 (PD)

4 K-Type-2 8 Not In Use

The fully assembled chamber is shown in figure 4-9

Fig 4-9 Fully Assembled Chamber

422 Quartz Crystal Microbalance

For measuring the deposition on our target for coating we used the Inficon SQM-160 RateThickness

Monitor It is an easy to use instrument for measuring many types of thin-film coatings as shown in

figure 4-10

(a) Front Panel (b) Back Panel

Fig 4-10 Inficon SQM-160

83

Table 4-1 shows the technical specifications for this equipment

Number of sensors 2 Standard 4 additional optional

Sensor Frequency Range 40 MHz ~ 60 MHz

Reference Frequency Accuracy 002

Thickness Display Resolution 1 Aring

Thickness Resolution 015 Aring (Std) 0037 Aring (Hi Res)

Density of Stored Films 05-9999 gmcc

Tooling 10-399

Z-Factor 010-1000

Final Thickness 0000-9999k Aring

Measurement Period 15 to 2 sec

Simulation Mode Yes

Frequency Mode Yes

Rate Resolution 011 Arings

Dual Crystal Yes

Etch Mode Yes

Crystal Tooling 10-399

Crystal Fail Min Max 40 to 60 MHz 41 to 61 MHz

Power 100-120 200-240~plusmn10 nominal 20W

Operation Environment 0degC ~ 50degC

0 ~ 80 RH non-condensing

0 ~ 2000 meters

Class 1 Equipment

Pollution Degree 2

Rack Dimensions 885mm x 2127mm x 1969mm

Weight 27 kg

Table 4-1 Inficon SQM-160 RateThickness Monitor Specs

84

To the SQM-160 we need to connect an Oscillator We use the Sigma Instruments Remote Oscillator

Ser No 2 268 as shown in figure 4-11

Fig 4-11 Sigma Instruments Remote Oscillator

The connections diagram is shown in figure 4-12

Fig 4-12 SQM-160 Connections Diagram

85

423 Turbo Pump

For our experiments we used the Pfeiffer TCP 015 Electronic Drive Unit shown below in figure 4-13

Table 4-2 shows the technical specifications for this equipment

(a) Front Panel (b) Back Panel

Fig 4-13 Pfeiffer TCP 015 Electronic Drive

Connection Voltage (100V) 90-112

Mains Frequency 5060 Hz

Start-up Current 22 A

Nominal Frequency 1500 Hz

Rotation Speed 10V = 1500Hz plusmn2

Analog Output Current 10 V = 25 A plusmn 5

Rotation Speed Switchpoint 750 Hz

Works Setting 8 min

Permissible Ambient Temperature 0degC ~ 40degC

Dimensions Front Panel 1285mm x 1063mm

Insertion Length 227mm

Weight 27 Kg

Table 4-2 Pfeiffer TCP 015 Electronic Drive Specs

86

The connections diagram is shown in figure 4-14

Fig 4-14Connections Diagram for Pfeiffer TCP 015

To measure the pressure inside the chamber we use the Granville Phillips 375 Convectron Vacuum

Pressure Controller shown in figure 4-15

(a) Front Panel (b) Back Panel

Fig 4-15 Granville Phillips 375 Convectron

87

Its dimensions are shown in figure 4-16

Fig 4-16 Dimensions of Convectron

Table 4-3 shows the technical specifications for this equipment

Table 4-3 Granville Phillips 375 Convectron Vacuum Pressure Controller Specs

88

424 Multimeter

For our experiment we used the Keithley 2000 Digital Multimeter as shown in figure 4-17

(a) Front Panel (b) Back Panel

Fig 4-17 Keithley Model 2000 6-12-Digit Digital Multimeter

Its technical specifications are shown in table 4-4

Table 4-4 Keithley Model 2000 6-12-Digit Digital Multimeter Specs

89

43 Experiment Procedure

1 Connecting together the equipment and the chamber

(1) We first connect the resonator to the thickness monitor and connect the other side to the

chamber

(2) We now connect the flexible tubes to the turbo pump on one side and to the chamber on the

other

(3) We need to check that tubes are tightly connected to avoid any leaks in the vacuum pumping

process which will not allow us to get to our goal of Torr As shown in figure 4-18

(4) Connect the convectron to the system as shown in figure 4-19

Fig 4-18 checking for leaks using alcohol

Fig 4-19 Convectron attached to System

90

(5) Attach the clamps of the Multimeter to the bottom of the chamber as shown in figure 4-20

(6) Place the Quartz crystal in place

(7) Close tight vacuum chamber

(8) Connect all electrical appliances to power source

Fig 4-20 Multimeter Connections

2 Starting up the System

(1) We turn on all the devices as such Check all systems are ready to function Reset all values

that might be left over from previous tests

(2) Start the thickness monitor and set all values for this experiment In our case we got to testing

the system but not actual coating So we used the simulation mode of the thickness monitor as

shown in figure 4-21

Fig 4-21 Simulation Mode

91

(3) Start the turbo pump Make sure the lid on the vacuum chamber is tightly closed

(4) Start convectron and record initial pressure

(5) Start Multimeter and record initial current

3 Coating Process

(1) If we have the deposition material inside the filament boat the power source for the high

current must be started as well

(2) Record all initial values for thickness current pressure

(3) For an ideal experiment we need a thickness of around 101 nm a pressure of Torr and

a current of 300 A

44 Results

From previous experiments we have shown that we can turn a LED into a laser by means of AR

Coating In figure 4-22 shown below we can compare the actual results of a Diode before and after AR

coating From the blue line we can see that when the diode is at a current of 15mA its light will change

from LED to laser and if we look at the red line its critical current is around 30 to 35 mA

Fig 4-22 AR Coating Comparison for Laser Diodes

This means that the light emitted is not as strong as if the diode had been coated because inside the

chamber there must be some excitation first so the reflectivity of both sides inside the diode must be high

So because of the coating in one of the sides we have opened a door and let the light come out so the

critical current is risen as such and will be higher value than that of before the coating

92

In the following figures we can see the difference between before and after coating in a material The

thickness is around 1016 nm for this material

Fig 4-23 Before Coating

Fig 4-24 After Coating

93

Chapter 5 CONCLUSIONS AND RECOMMENDATIONS

51 Conclusions

For the first part of this independent study taking into consideration the data that came out of our

research and that sent by the provider we can say

1 SUM 23 after heat treatment will unexpectedly develop cracking in the middle of the tensile

testing process and suddenly break

2 Itrsquos possible that in the process of heat treatment to the SUM 23 material the treatment was not

uniform and this will create a pre-loaded moment force on one side that pushes on the other side

of the specimen resulting in material deformation

3 In the process of attaching the strain gauges to the materials it is very easy to make errors due to

poor adhesion or sudden removal in the tensile testing process

For our second part of the independent study the following can be made

1 At the beginning of this independent study we had no idea what Bose-Einstein Condensate was

or what was its purpose After much literature we finally comprehended the basic principles to

put into practice for our research

2 Our systemrsquos basic working principles and equipmentrsquos complexity are a little difficult to grasp

but hopefully we were able to understand enough of it

3 Theoretically from relation between the power and current we can know the advantages and

disadvantages of AR Coating

4 We were able to assemble the system and run test on its functions Even though we were able to

do this there is still much more work left to do with this system

52 Recommendations

For the Tensile Testing the following can be said

1 Ask the provider to check on the process of heat treatment on the SUM 23 material and give

them the information we have gathered through our test so they can correct for the mechanical

properties found if any change is needed

2 To avoid the problem of the inaccuracy of the poor adhesion of strain gauges we can attach

multiple strain gauges to the same one specimen so as to correlate data and improve our results

For the AR Coating the following can be said

1 We need to make sure that there are no physical defects on the main body of the chamber so as to

achieve maximum efficiency in the vacuum process If there was then the vacuum will arrive to

certain point and then start to decrease

2 It would be preferable to add some sort of visual aid that will allow the user to check the inside of

the chamber without actually opening it This will help us determine at what times we should

manipulate the current to better evaporate the substrate

94

REFERENCES

[1] A L Window Strain Gauge Technology Elsevier Applied Science London and New York 2nd

Edition 1992

[2] CC Perry and HR Lissner Strain Gauge Primer McGraw-Hill Book Co Inc New York 1955

[3] James W Dally William F Riley McGraw-Hill 1978

[4] University of Colorado Boulder BEC - What is it and where did the idea come from

httpwwwcoloradoeduphysics2000becwhat_is_ithtml

[5] Ultraslow Light amp Bose-Einstein Condensates Two-way Control with Coherent Light amp Atom

Fields Harvard Hau Lab Dr Lene Vestergaard Hau Optics amp Photonics News 16 1995

[6] The Art of Taming Light Ultra-slow and Stopped Light Harvard Hau Lab Dr Lene

Vestergaard Hau Europhysics News 2004

[7] Nonlinear Optics Shocking Superfluids Harvard Hau Lab Dr Lene Vestergaard Hau Nature

Physics 2007

[8] Model P3 Strain Indicator and Recorder Instruction Manual Vishay Micro-Measurements 2005

[9] Granville-Phillips Series 375 Convectron Vacuum Gauge Controller Instruction Manual Brooks

Automation 2008

[10] Effect of Film Thickness on the Validity of the Sauerbrey Equation for Hydrated Polyelectrolyte

Films Vogt Lin Wu White 2004

[11] Quartz Crystal Microbalance Study of DNA Immobilization and Hybridization for DNA Sensor

Development Chang Zhao 2008

[12] Installation of Strain Gages with SR-4 PrecoatAdhesive Vishay Micro-Measurements 2005

[13] Strain Gauge Measurement ndash A Tutorial National Instruments 1998

[14] Correlation between Vickers Hardness Number and Yield Stress of Cold-Formed Products

Yavuz Tekkaya

[15] httpsenwikipediaorg

Page 47: PC Hinge Materials Testing and AR Laser Diode Coating

47

324 Specimen Measurements

The tensile specimens used in this research are compliant of ASTM E8 Tensile parameters as shown

in figure 3-6

Fig 3-6 Tensile Specimen

Diameter

D(mm)

Gauge

Length

G(mm)

Smallest

Arc

Radius

R(mm)

Shortest

Area

A(mm)

Total

Length

L(mm)

Clamping

Area

Length

B(mm)

Clamping

Area

Diameter

C(mm)

Bar 125 02 625 01 gt10 gt75 ~ 145 ~ 35 20

Table 3-3 Specifications for Round Bar

33 Experiment Procedure

1 Attaching the Strain Gauge to the Tensile Specimen

(1) Prepare 1 ASTM E8 compliant tensile specimen round bar as shown in figure 3-7

(2) Prepare Strain Gauge as those described in table 3-4

(3) Prepare other consumables and adhesive agent such as epoxy adhesive or

cyanoacrylate adhesive as shown in figure 3-8

48

Fig 3-7 Actual Tensile Specimen

Fig 3-8 Other Materials Used (Such as Alcohol gauze transparent tape adhesive)

Gage Type

EA-06-120LZ-120E

Resistance in ohms at 24∘C

1200plusmn03

Gage Factor at 24∘C

2075plusmn05

Transverse Sensitivity at 24∘C

(+07plusmn02)

Table 3-4 Specifications for Strain Gauge

2 Attaching Strain Gauge

As shown in following figures we shall explain the attachment of the strain gauge

(1) Use sand paper and a rasp to clean thoroughly the surface where the strain gauge will be

attached to

49

(a)

(2) Use alcohol to wash the surface where the strain gauge will be attached and use gauze to rub

it off

(b)

(3) Find a clean surface and clean it with alcohol and gauze

(c)

(4) Place the strain gauge in the clean surface Use a piece of transparent tape on top of the strain

gauge after securely placed rip it off the surface carefully

50

(d)

(5) Use a piece of white paper to mark the place where the strain gauge will be attached and in

this way we can make sure that the strain gauge will be placed as horizontally and vertically

correct as possible

(e)

(6) In the place where we had our mark place the strain gauge

(f)

(7) Carefully lift one side of the tape and apply some of the adhesive agent to both the strain

gauge and specimenrsquos surface

(g)

51

(8) We need to make sure that the gauge and the specimen will be firmly attached so we gently

apply pressure with our thumb

(h)

(9) After the adhesive is fully dry we can carefully rip off the tape

(i)

(10) We need to do the whole process twice one for the horizontally placed strain gauge and one

for the vertically placed strain gauge

52

(j)

(11) We now proceed to solder the wires to the strain gauge

(k)

(12) After soldering we use a Volt Multimeter to measure that there is no contact between wires

If there is none then the specimen is ready for testing

(l)

(13) We now need to measure a 5cm distance and mark it to check and compare the elongation

before and after the tensile testing

(m)

53

Fig 3-9 Specimen-Strain Gauge Process

3 Tensile Test

(1) Enter the computer application that controls the tensile testing machine

(2) Turn on the tensile testing machine main switch

(3) Adjust the hydraulic pump to go back to its original position

(4) Bring the lowering motor down to a distance enough so as to attach the tensile specimen to the

system open the clamps and secure the specimen

(a)

(5) Connect all the necessary wires to the strain indicator equipment

54

(b)

(6) Start the ascending motor and wait for the expansion

(c)

Fig 3-10 Specimen-Tensile Testing Process

4 Start the Test

(1) Enter the software application and enter some variables needed for the experiment in the

specific screen

(2) Go back to the main screen and press the [測試] (measure) button to start the test and auto

recording in the software

(3) After the specimen breaks the mechanical device will automatically stop and ask the user to

enter the total displacement We take out the specimen from the testing machine and adjust the

machinersquos position back to its original position

(4) Save the results information

(5) Record the results from the strain indicator

34 Results

From this experiment we can get the Poissonrsquos Ratio Youngrsquos Modulus and Yield Strength etc and

because of the slippage phenomenon in the clamp at the moment of the test then the Elastic Limit will

display some yield phenomena So omit any undesirable results we just take the Yield portion of the

results as reference

In the process of the experiment the most important part to attend to is the attaching of the strain

gauge because the gaugersquos purpose is to measure the strain developed during the test and this strain

might be very small If the gaugersquos angle change during the test ie is not well attached this will affect

the accuracy of the measurements of Poissonrsquos ratio and Youngrsquos modulus

55

The materials provided by the manufacturer are SUM 23 and SUM 43 steel round bars and these two

types of materials have been through different heat treatment processes so they can be sub-divided

further into untreated material heat-treated material and black surface heat treated material for the two

materials with heat treatment the treatment process and finished are different In the end we only have

the mechanical properties that were calculated after our research of these materials

All of the specifications are identical to those shown in figure 3-6

341 SUM 23

Fig 3-11 SUM 23 Untreated Material

Number 7 10

Hardness(HRB) 74 75

Yield Stress (MPa) 448 440

Tensile Strength (MPa) 544 560

Poissonrsquos Ratio 029 027

Youngrsquos Modulus (GPa) 203 210

Cut-off Area Shrinking () 42 41

Elongation () 1125 1011

Table 3-5 Mechanical Properties of SUM 23 Untreated

56

Stress-Strain Diagram

(a)

(b)

57

Fig 3-12 Stress-Strain Diagrams for (a) 7 Round Bar and (b) 10 Round Bar

Cut-Off Area

(a)

(b)

Fig 3-13 Cut-Off Area of (a) 7 Round Bar and (b) 10 Round Bar

58

SUM 23 Nickel Round Bar

Fig 3-14 SUM 23 Nickel Material

Number 1 2 3 4

Hardness(HRB) 48 50 49 48

Yield Stress (MPa) 370 370 380 400

Tensile Strength (MPa) 455 451 450 450

Poissonrsquos Ratio 028 046 029 026

Youngrsquos Modulus (GPa) 243 303 246 206

Cut-off Area Shrinking () 803 803 726 601

Elongation () 566 65 602 647

Table 3-6 Mechanical Properties of SUM 23 Nickel

59

Stress-Strain Diagram

(a)

60

(b)

(c)

(d)

61

Fig 3-15 Stress-Strain Diagrams for (a) 1 Round Bar (b) 2 Round Bar (c) 3 Round Bar and (d)

4 Round Bar

Cut-Off Area

(a)

(b)

62

(c)

(d)

Fig 3-16 Cut-Off Area of (a) 1 Round Bar (b) 2 Round Bar (c) 3 Round Bar and (d) 4 Round

Bar

63

SUM 23 Black Surface Round Bar

Fig 3-17 SUM 23 Black Surface Material

Number 1 2 3

Hardness(HRB) 51 50 51

Yield Stress (MPa) 378 371 369

Tensile Strength (MPa) 467 465 464

Poissonrsquos Ratio 03 016 04

Youngrsquos Modulus (GPa) 215 266 266

Cut-off Area Shrinking () 986 94 848

Elongation () 748 805 761

Table 3-7 Mechanical Properties of SUM 23 Black Surface Material

64

Stress-Strain Diagram

(a)

(b)

65

(c)

Fig 3-18 Stress-Strain Diagrams for (a) 1 Round Bar 2 Round Bar and (c) 3 Round Bar

Cut-Off Surface

(a)

66

(b)

(c)

Fig 3-19 Cut-Off Surface of (a) 1 Round Bar 2 Round Bar and (c) 3 Round Bar

67

342 SUM 43

Fig 3-20 Untreated SUM 43 Untreated Material

Number 1 5

Hardness(HRB) 76 75

Yield Stress (MPa) 572 594

Tensile Strength (MPa) 743 785

Poissonrsquos Ratio 027 029

Youngrsquos Modulus (GPa) 200 202

Cut-off Area Shrinking () 338 2944

Elongation () 857 894

Table 3-8 Mechanical Properties of SUM 43 Untreated

68

Stress-Strain Diagrams

(a)

(b)

Fig 3-21 Stress-Strain Diagrams for SUM 43 (a) 1 Round Bar and (b) 5 Round Bar

69

Cut-Off Area

(a)

(b)

Fig 3-22 Cut-Off Area of SUM 43 (a) 1 Round Bar and (b) 5 Round Bar

70

SUM 43 Nickel Round Bar

Fig 3-23 SUM 43 Nickel Material

Number 4 5

Hardness(HRB) 51 50

Yield Stress (MPa) 1580 1544

Tensile Strength (MPa) 1639 1625

Poissonrsquos Ratio 03 028

Youngrsquos Modulus (GPa) 194 201

Cut-off Area Shrinking () 1697 137

Elongation () 376 265

Table 3-9 Mechanical Properties of SUM 43 Nickel

71

Stress-Strain Diagrams

(a)

(b)

Fig 3-24 Stress-Strain Diagrams for (a) 4 Round Bar and (b) 5 Round Bar

72

Cut-Off Area

(a)

(b)

Fig 3-25 Cut-Off Area of (a) 4 Round Bar and (b) 5 Round Bar

73

SUM 43 Black Surface Material

Fig 3-26 SUM 43 Black Surface Material

Number 3 5

Hardness(HRB) 56 56

Yield Stress (MPa) 1416 1361

Tensile Strength (MPa) 1591 1402

Poissonrsquos Ratio 029 031

Youngrsquos Modulus (GPa) 200 202

Cut-off Area Shrinking () 139 124

Elongation () 24 24

Table 3-10 Mechanical Properties of SUM 43 Black Surface Material

74

Stress-Strain Diagrams

0 2 4 6 8 10 12 14

-200

0

200

400

600

800

1000

1200

1400

1600

1800

應力 (MPa)

應變()

(a)

0 2 4 6 8 10

-200

0

200

400

600

800

1000

1200

1400

1600

應力

(MPa)

位移 ()

(b)

Fig 3-27 Stress-Strain Diagrams for (a) 3 Round Bar and (b) 5 Round Bar

(Note These curves were formulated using Visual Solutions Inc VisSim Software)

75

Cut-Off Area

(a)

(b)

Fig 3-28 Cut-Off Area of (a) 3 Round Bar and (b) 5 Round Bar

76

The force value (N) was retrieved from the Universal Testing Machine

The Poissonrsquos Ratio (ε) is calculated as

ε =

the values for the Poissonrsquos Ratio are in average around 0297

The Youngrsquos Modulus (E) is calculated as

E =

Where

Stress =

Cross-sectional Area =

where D is the Diameter

The value for D was in average around 1258 mm

The values shown by the computer because there is Slippage phenomena between the Clamp and the

specimen will not be taken into consideration for the elongation strain and Youngrsquos modulus and we will

refer to the values that we have meticulously calculated

77

Chapter 4 AR COATING IN DEPTH

41 Experimentrsquos Purpose and Principles

By means of a vacuum chamber and several other instruments we intend to apply Anti-Reflective

Coating using deposition process to a laser diode and in this way reduce its refraction so as to make it

lose less light in the process of amplification and we can control certain wavelengths we want produced

for certain desired applications in our case we are attempting to re-create a Bose-Einstein Condensate

An optimal BEC apparatus is shown in figure 4-1

Fig 4-1 BEC Apparatus

The main point of this experiment is to build a vacuum chamber system attach all the instrumentation

needed (Vacuum pump deposition meter and voltmeter) and use it to apply AR coating to a laser diode

After we have accomplished the AR coating other team will be in charge of designing the BEC apparatus

and use the results of our research

78

42 Experimentrsquos Equipment

421 Vacuum Chamber

For this research we designed a vacuum chamber whose main body is shown in figure 4-2 Its

dimensions are

Width 240 mm

Length 240 mm

Height 200 mm

Outer Diameter 4 in

Inner Diameter 15 in

Fig 4-2 Vacuum Chamber Main Body

The chamber is made up of 6 pass ways pass way A is the connection with the Laser Deposition

Equipment pass way B is the connection with the Turbo Pump and pass way C is for the connection with

the Deposition Source

A

C

B

79

Pass way C is for the deposition source as mentioned above This is a system where a thermal

resistance is heated by passing a high current through it which heats up a filament boat (made of tungsten)

where the material to be evaporated is place We control the temperature as such that the material will

evaporate and the heat will not cause the filament boat to crack

Because P = Isup2 R (where P is power I is current and R is resistance) to avoid the current to flow

where it is not desired we decided that the material for the Thermocouple shown in figure 4-3 should be

Copper ᴓ 63 mm We choose it that way because Copper has very good heat dissipation characteristics

and the resistance value is low It can reduce the value of the current enough to make the thermocouple to

create heat

Fig 4-3 Thermocouple

To the thermocouple we attach the tungsten filament boat We need to take notice of materials to be

used in this design because when using high current the tungsten filament boar will heat up and so the

material must be able to keep up with the heating potential of tungsten and has a low coefficient of heat

dissipation to avoid the tungsten to fail when heating up and therefore not evaporating Considering all

this we decide to use Stainless Steel

Because this clamp will be assembled inside the chamber after many revisions it was determined it

will have the shape shown in figure 4-4

Fig 4-4 Filament Boat Clamp Design

80

For the tungsten filament boat we bought the product from a distributor The dimensions are

Length 100 mm

Width 10 mm

Height 1 mm

Our thermocouple is 15 in but the pass way C is 4 in so we need to attach a Flange that connects

15in to 4in Because these specifications are quite difficult to achieve by Milling we had to use

electrical wire cutting

For the laser clamping system where the laser that is going to be AR coated will be placed will be

connected to pass way A the assembly is shown in figure 4-5 below

Fig 4-5 Cover Assembly

For this design we used an O-ring instead of a gasket so as to save time The design of the assembly

where the laser will be placed is shown in figure 4-6

Fig 4-6 Upper Cover Inner Assembly

D

E

F

81

Point D is the plate in the assembly where the laser diode will be fixed Because of the easy

processing we decide to use Aluminum and it is screwed to the top cover Point E is the connection for

the Quartz crystal resonator and it is designed in the same as point F in this way the results of the quartz

microbalance system will be more accurate in real time Point F is the final resting place for the laser

diode We use a Thor Labs Base with dimensions of ᴓ 9mm and ᴓ 56mm for two different size laser

diodes It just needs to be plugged in for easy installation

From figure 4-6 we know that the system needs signal system connections and because of the

change in temperature inside the chamber this could affect the functioning of the quartz microbalance so

we also need to install water tubes for cooling This is shown in figure 4-7 below

Fig 4-7 Diagram of Upper Cover Connections

In figure 4-8 we show the Feed through connections and their functions

Fig 4-8 Feed through Diagram

82

1 SQM-160 wire 5 Laser Connection 1 (Vin)

2 SQM-160 (G) 6 Laser Connection 2 (G)

3 K-Type-1 7 Laser Connection 3 (PD)

4 K-Type-2 8 Not In Use

The fully assembled chamber is shown in figure 4-9

Fig 4-9 Fully Assembled Chamber

422 Quartz Crystal Microbalance

For measuring the deposition on our target for coating we used the Inficon SQM-160 RateThickness

Monitor It is an easy to use instrument for measuring many types of thin-film coatings as shown in

figure 4-10

(a) Front Panel (b) Back Panel

Fig 4-10 Inficon SQM-160

83

Table 4-1 shows the technical specifications for this equipment

Number of sensors 2 Standard 4 additional optional

Sensor Frequency Range 40 MHz ~ 60 MHz

Reference Frequency Accuracy 002

Thickness Display Resolution 1 Aring

Thickness Resolution 015 Aring (Std) 0037 Aring (Hi Res)

Density of Stored Films 05-9999 gmcc

Tooling 10-399

Z-Factor 010-1000

Final Thickness 0000-9999k Aring

Measurement Period 15 to 2 sec

Simulation Mode Yes

Frequency Mode Yes

Rate Resolution 011 Arings

Dual Crystal Yes

Etch Mode Yes

Crystal Tooling 10-399

Crystal Fail Min Max 40 to 60 MHz 41 to 61 MHz

Power 100-120 200-240~plusmn10 nominal 20W

Operation Environment 0degC ~ 50degC

0 ~ 80 RH non-condensing

0 ~ 2000 meters

Class 1 Equipment

Pollution Degree 2

Rack Dimensions 885mm x 2127mm x 1969mm

Weight 27 kg

Table 4-1 Inficon SQM-160 RateThickness Monitor Specs

84

To the SQM-160 we need to connect an Oscillator We use the Sigma Instruments Remote Oscillator

Ser No 2 268 as shown in figure 4-11

Fig 4-11 Sigma Instruments Remote Oscillator

The connections diagram is shown in figure 4-12

Fig 4-12 SQM-160 Connections Diagram

85

423 Turbo Pump

For our experiments we used the Pfeiffer TCP 015 Electronic Drive Unit shown below in figure 4-13

Table 4-2 shows the technical specifications for this equipment

(a) Front Panel (b) Back Panel

Fig 4-13 Pfeiffer TCP 015 Electronic Drive

Connection Voltage (100V) 90-112

Mains Frequency 5060 Hz

Start-up Current 22 A

Nominal Frequency 1500 Hz

Rotation Speed 10V = 1500Hz plusmn2

Analog Output Current 10 V = 25 A plusmn 5

Rotation Speed Switchpoint 750 Hz

Works Setting 8 min

Permissible Ambient Temperature 0degC ~ 40degC

Dimensions Front Panel 1285mm x 1063mm

Insertion Length 227mm

Weight 27 Kg

Table 4-2 Pfeiffer TCP 015 Electronic Drive Specs

86

The connections diagram is shown in figure 4-14

Fig 4-14Connections Diagram for Pfeiffer TCP 015

To measure the pressure inside the chamber we use the Granville Phillips 375 Convectron Vacuum

Pressure Controller shown in figure 4-15

(a) Front Panel (b) Back Panel

Fig 4-15 Granville Phillips 375 Convectron

87

Its dimensions are shown in figure 4-16

Fig 4-16 Dimensions of Convectron

Table 4-3 shows the technical specifications for this equipment

Table 4-3 Granville Phillips 375 Convectron Vacuum Pressure Controller Specs

88

424 Multimeter

For our experiment we used the Keithley 2000 Digital Multimeter as shown in figure 4-17

(a) Front Panel (b) Back Panel

Fig 4-17 Keithley Model 2000 6-12-Digit Digital Multimeter

Its technical specifications are shown in table 4-4

Table 4-4 Keithley Model 2000 6-12-Digit Digital Multimeter Specs

89

43 Experiment Procedure

1 Connecting together the equipment and the chamber

(1) We first connect the resonator to the thickness monitor and connect the other side to the

chamber

(2) We now connect the flexible tubes to the turbo pump on one side and to the chamber on the

other

(3) We need to check that tubes are tightly connected to avoid any leaks in the vacuum pumping

process which will not allow us to get to our goal of Torr As shown in figure 4-18

(4) Connect the convectron to the system as shown in figure 4-19

Fig 4-18 checking for leaks using alcohol

Fig 4-19 Convectron attached to System

90

(5) Attach the clamps of the Multimeter to the bottom of the chamber as shown in figure 4-20

(6) Place the Quartz crystal in place

(7) Close tight vacuum chamber

(8) Connect all electrical appliances to power source

Fig 4-20 Multimeter Connections

2 Starting up the System

(1) We turn on all the devices as such Check all systems are ready to function Reset all values

that might be left over from previous tests

(2) Start the thickness monitor and set all values for this experiment In our case we got to testing

the system but not actual coating So we used the simulation mode of the thickness monitor as

shown in figure 4-21

Fig 4-21 Simulation Mode

91

(3) Start the turbo pump Make sure the lid on the vacuum chamber is tightly closed

(4) Start convectron and record initial pressure

(5) Start Multimeter and record initial current

3 Coating Process

(1) If we have the deposition material inside the filament boat the power source for the high

current must be started as well

(2) Record all initial values for thickness current pressure

(3) For an ideal experiment we need a thickness of around 101 nm a pressure of Torr and

a current of 300 A

44 Results

From previous experiments we have shown that we can turn a LED into a laser by means of AR

Coating In figure 4-22 shown below we can compare the actual results of a Diode before and after AR

coating From the blue line we can see that when the diode is at a current of 15mA its light will change

from LED to laser and if we look at the red line its critical current is around 30 to 35 mA

Fig 4-22 AR Coating Comparison for Laser Diodes

This means that the light emitted is not as strong as if the diode had been coated because inside the

chamber there must be some excitation first so the reflectivity of both sides inside the diode must be high

So because of the coating in one of the sides we have opened a door and let the light come out so the

critical current is risen as such and will be higher value than that of before the coating

92

In the following figures we can see the difference between before and after coating in a material The

thickness is around 1016 nm for this material

Fig 4-23 Before Coating

Fig 4-24 After Coating

93

Chapter 5 CONCLUSIONS AND RECOMMENDATIONS

51 Conclusions

For the first part of this independent study taking into consideration the data that came out of our

research and that sent by the provider we can say

1 SUM 23 after heat treatment will unexpectedly develop cracking in the middle of the tensile

testing process and suddenly break

2 Itrsquos possible that in the process of heat treatment to the SUM 23 material the treatment was not

uniform and this will create a pre-loaded moment force on one side that pushes on the other side

of the specimen resulting in material deformation

3 In the process of attaching the strain gauges to the materials it is very easy to make errors due to

poor adhesion or sudden removal in the tensile testing process

For our second part of the independent study the following can be made

1 At the beginning of this independent study we had no idea what Bose-Einstein Condensate was

or what was its purpose After much literature we finally comprehended the basic principles to

put into practice for our research

2 Our systemrsquos basic working principles and equipmentrsquos complexity are a little difficult to grasp

but hopefully we were able to understand enough of it

3 Theoretically from relation between the power and current we can know the advantages and

disadvantages of AR Coating

4 We were able to assemble the system and run test on its functions Even though we were able to

do this there is still much more work left to do with this system

52 Recommendations

For the Tensile Testing the following can be said

1 Ask the provider to check on the process of heat treatment on the SUM 23 material and give

them the information we have gathered through our test so they can correct for the mechanical

properties found if any change is needed

2 To avoid the problem of the inaccuracy of the poor adhesion of strain gauges we can attach

multiple strain gauges to the same one specimen so as to correlate data and improve our results

For the AR Coating the following can be said

1 We need to make sure that there are no physical defects on the main body of the chamber so as to

achieve maximum efficiency in the vacuum process If there was then the vacuum will arrive to

certain point and then start to decrease

2 It would be preferable to add some sort of visual aid that will allow the user to check the inside of

the chamber without actually opening it This will help us determine at what times we should

manipulate the current to better evaporate the substrate

94

REFERENCES

[1] A L Window Strain Gauge Technology Elsevier Applied Science London and New York 2nd

Edition 1992

[2] CC Perry and HR Lissner Strain Gauge Primer McGraw-Hill Book Co Inc New York 1955

[3] James W Dally William F Riley McGraw-Hill 1978

[4] University of Colorado Boulder BEC - What is it and where did the idea come from

httpwwwcoloradoeduphysics2000becwhat_is_ithtml

[5] Ultraslow Light amp Bose-Einstein Condensates Two-way Control with Coherent Light amp Atom

Fields Harvard Hau Lab Dr Lene Vestergaard Hau Optics amp Photonics News 16 1995

[6] The Art of Taming Light Ultra-slow and Stopped Light Harvard Hau Lab Dr Lene

Vestergaard Hau Europhysics News 2004

[7] Nonlinear Optics Shocking Superfluids Harvard Hau Lab Dr Lene Vestergaard Hau Nature

Physics 2007

[8] Model P3 Strain Indicator and Recorder Instruction Manual Vishay Micro-Measurements 2005

[9] Granville-Phillips Series 375 Convectron Vacuum Gauge Controller Instruction Manual Brooks

Automation 2008

[10] Effect of Film Thickness on the Validity of the Sauerbrey Equation for Hydrated Polyelectrolyte

Films Vogt Lin Wu White 2004

[11] Quartz Crystal Microbalance Study of DNA Immobilization and Hybridization for DNA Sensor

Development Chang Zhao 2008

[12] Installation of Strain Gages with SR-4 PrecoatAdhesive Vishay Micro-Measurements 2005

[13] Strain Gauge Measurement ndash A Tutorial National Instruments 1998

[14] Correlation between Vickers Hardness Number and Yield Stress of Cold-Formed Products

Yavuz Tekkaya

[15] httpsenwikipediaorg

Page 48: PC Hinge Materials Testing and AR Laser Diode Coating

48

Fig 3-7 Actual Tensile Specimen

Fig 3-8 Other Materials Used (Such as Alcohol gauze transparent tape adhesive)

Gage Type

EA-06-120LZ-120E

Resistance in ohms at 24∘C

1200plusmn03

Gage Factor at 24∘C

2075plusmn05

Transverse Sensitivity at 24∘C

(+07plusmn02)

Table 3-4 Specifications for Strain Gauge

2 Attaching Strain Gauge

As shown in following figures we shall explain the attachment of the strain gauge

(1) Use sand paper and a rasp to clean thoroughly the surface where the strain gauge will be

attached to

49

(a)

(2) Use alcohol to wash the surface where the strain gauge will be attached and use gauze to rub

it off

(b)

(3) Find a clean surface and clean it with alcohol and gauze

(c)

(4) Place the strain gauge in the clean surface Use a piece of transparent tape on top of the strain

gauge after securely placed rip it off the surface carefully

50

(d)

(5) Use a piece of white paper to mark the place where the strain gauge will be attached and in

this way we can make sure that the strain gauge will be placed as horizontally and vertically

correct as possible

(e)

(6) In the place where we had our mark place the strain gauge

(f)

(7) Carefully lift one side of the tape and apply some of the adhesive agent to both the strain

gauge and specimenrsquos surface

(g)

51

(8) We need to make sure that the gauge and the specimen will be firmly attached so we gently

apply pressure with our thumb

(h)

(9) After the adhesive is fully dry we can carefully rip off the tape

(i)

(10) We need to do the whole process twice one for the horizontally placed strain gauge and one

for the vertically placed strain gauge

52

(j)

(11) We now proceed to solder the wires to the strain gauge

(k)

(12) After soldering we use a Volt Multimeter to measure that there is no contact between wires

If there is none then the specimen is ready for testing

(l)

(13) We now need to measure a 5cm distance and mark it to check and compare the elongation

before and after the tensile testing

(m)

53

Fig 3-9 Specimen-Strain Gauge Process

3 Tensile Test

(1) Enter the computer application that controls the tensile testing machine

(2) Turn on the tensile testing machine main switch

(3) Adjust the hydraulic pump to go back to its original position

(4) Bring the lowering motor down to a distance enough so as to attach the tensile specimen to the

system open the clamps and secure the specimen

(a)

(5) Connect all the necessary wires to the strain indicator equipment

54

(b)

(6) Start the ascending motor and wait for the expansion

(c)

Fig 3-10 Specimen-Tensile Testing Process

4 Start the Test

(1) Enter the software application and enter some variables needed for the experiment in the

specific screen

(2) Go back to the main screen and press the [測試] (measure) button to start the test and auto

recording in the software

(3) After the specimen breaks the mechanical device will automatically stop and ask the user to

enter the total displacement We take out the specimen from the testing machine and adjust the

machinersquos position back to its original position

(4) Save the results information

(5) Record the results from the strain indicator

34 Results

From this experiment we can get the Poissonrsquos Ratio Youngrsquos Modulus and Yield Strength etc and

because of the slippage phenomenon in the clamp at the moment of the test then the Elastic Limit will

display some yield phenomena So omit any undesirable results we just take the Yield portion of the

results as reference

In the process of the experiment the most important part to attend to is the attaching of the strain

gauge because the gaugersquos purpose is to measure the strain developed during the test and this strain

might be very small If the gaugersquos angle change during the test ie is not well attached this will affect

the accuracy of the measurements of Poissonrsquos ratio and Youngrsquos modulus

55

The materials provided by the manufacturer are SUM 23 and SUM 43 steel round bars and these two

types of materials have been through different heat treatment processes so they can be sub-divided

further into untreated material heat-treated material and black surface heat treated material for the two

materials with heat treatment the treatment process and finished are different In the end we only have

the mechanical properties that were calculated after our research of these materials

All of the specifications are identical to those shown in figure 3-6

341 SUM 23

Fig 3-11 SUM 23 Untreated Material

Number 7 10

Hardness(HRB) 74 75

Yield Stress (MPa) 448 440

Tensile Strength (MPa) 544 560

Poissonrsquos Ratio 029 027

Youngrsquos Modulus (GPa) 203 210

Cut-off Area Shrinking () 42 41

Elongation () 1125 1011

Table 3-5 Mechanical Properties of SUM 23 Untreated

56

Stress-Strain Diagram

(a)

(b)

57

Fig 3-12 Stress-Strain Diagrams for (a) 7 Round Bar and (b) 10 Round Bar

Cut-Off Area

(a)

(b)

Fig 3-13 Cut-Off Area of (a) 7 Round Bar and (b) 10 Round Bar

58

SUM 23 Nickel Round Bar

Fig 3-14 SUM 23 Nickel Material

Number 1 2 3 4

Hardness(HRB) 48 50 49 48

Yield Stress (MPa) 370 370 380 400

Tensile Strength (MPa) 455 451 450 450

Poissonrsquos Ratio 028 046 029 026

Youngrsquos Modulus (GPa) 243 303 246 206

Cut-off Area Shrinking () 803 803 726 601

Elongation () 566 65 602 647

Table 3-6 Mechanical Properties of SUM 23 Nickel

59

Stress-Strain Diagram

(a)

60

(b)

(c)

(d)

61

Fig 3-15 Stress-Strain Diagrams for (a) 1 Round Bar (b) 2 Round Bar (c) 3 Round Bar and (d)

4 Round Bar

Cut-Off Area

(a)

(b)

62

(c)

(d)

Fig 3-16 Cut-Off Area of (a) 1 Round Bar (b) 2 Round Bar (c) 3 Round Bar and (d) 4 Round

Bar

63

SUM 23 Black Surface Round Bar

Fig 3-17 SUM 23 Black Surface Material

Number 1 2 3

Hardness(HRB) 51 50 51

Yield Stress (MPa) 378 371 369

Tensile Strength (MPa) 467 465 464

Poissonrsquos Ratio 03 016 04

Youngrsquos Modulus (GPa) 215 266 266

Cut-off Area Shrinking () 986 94 848

Elongation () 748 805 761

Table 3-7 Mechanical Properties of SUM 23 Black Surface Material

64

Stress-Strain Diagram

(a)

(b)

65

(c)

Fig 3-18 Stress-Strain Diagrams for (a) 1 Round Bar 2 Round Bar and (c) 3 Round Bar

Cut-Off Surface

(a)

66

(b)

(c)

Fig 3-19 Cut-Off Surface of (a) 1 Round Bar 2 Round Bar and (c) 3 Round Bar

67

342 SUM 43

Fig 3-20 Untreated SUM 43 Untreated Material

Number 1 5

Hardness(HRB) 76 75

Yield Stress (MPa) 572 594

Tensile Strength (MPa) 743 785

Poissonrsquos Ratio 027 029

Youngrsquos Modulus (GPa) 200 202

Cut-off Area Shrinking () 338 2944

Elongation () 857 894

Table 3-8 Mechanical Properties of SUM 43 Untreated

68

Stress-Strain Diagrams

(a)

(b)

Fig 3-21 Stress-Strain Diagrams for SUM 43 (a) 1 Round Bar and (b) 5 Round Bar

69

Cut-Off Area

(a)

(b)

Fig 3-22 Cut-Off Area of SUM 43 (a) 1 Round Bar and (b) 5 Round Bar

70

SUM 43 Nickel Round Bar

Fig 3-23 SUM 43 Nickel Material

Number 4 5

Hardness(HRB) 51 50

Yield Stress (MPa) 1580 1544

Tensile Strength (MPa) 1639 1625

Poissonrsquos Ratio 03 028

Youngrsquos Modulus (GPa) 194 201

Cut-off Area Shrinking () 1697 137

Elongation () 376 265

Table 3-9 Mechanical Properties of SUM 43 Nickel

71

Stress-Strain Diagrams

(a)

(b)

Fig 3-24 Stress-Strain Diagrams for (a) 4 Round Bar and (b) 5 Round Bar

72

Cut-Off Area

(a)

(b)

Fig 3-25 Cut-Off Area of (a) 4 Round Bar and (b) 5 Round Bar

73

SUM 43 Black Surface Material

Fig 3-26 SUM 43 Black Surface Material

Number 3 5

Hardness(HRB) 56 56

Yield Stress (MPa) 1416 1361

Tensile Strength (MPa) 1591 1402

Poissonrsquos Ratio 029 031

Youngrsquos Modulus (GPa) 200 202

Cut-off Area Shrinking () 139 124

Elongation () 24 24

Table 3-10 Mechanical Properties of SUM 43 Black Surface Material

74

Stress-Strain Diagrams

0 2 4 6 8 10 12 14

-200

0

200

400

600

800

1000

1200

1400

1600

1800

應力 (MPa)

應變()

(a)

0 2 4 6 8 10

-200

0

200

400

600

800

1000

1200

1400

1600

應力

(MPa)

位移 ()

(b)

Fig 3-27 Stress-Strain Diagrams for (a) 3 Round Bar and (b) 5 Round Bar

(Note These curves were formulated using Visual Solutions Inc VisSim Software)

75

Cut-Off Area

(a)

(b)

Fig 3-28 Cut-Off Area of (a) 3 Round Bar and (b) 5 Round Bar

76

The force value (N) was retrieved from the Universal Testing Machine

The Poissonrsquos Ratio (ε) is calculated as

ε =

the values for the Poissonrsquos Ratio are in average around 0297

The Youngrsquos Modulus (E) is calculated as

E =

Where

Stress =

Cross-sectional Area =

where D is the Diameter

The value for D was in average around 1258 mm

The values shown by the computer because there is Slippage phenomena between the Clamp and the

specimen will not be taken into consideration for the elongation strain and Youngrsquos modulus and we will

refer to the values that we have meticulously calculated

77

Chapter 4 AR COATING IN DEPTH

41 Experimentrsquos Purpose and Principles

By means of a vacuum chamber and several other instruments we intend to apply Anti-Reflective

Coating using deposition process to a laser diode and in this way reduce its refraction so as to make it

lose less light in the process of amplification and we can control certain wavelengths we want produced

for certain desired applications in our case we are attempting to re-create a Bose-Einstein Condensate

An optimal BEC apparatus is shown in figure 4-1

Fig 4-1 BEC Apparatus

The main point of this experiment is to build a vacuum chamber system attach all the instrumentation

needed (Vacuum pump deposition meter and voltmeter) and use it to apply AR coating to a laser diode

After we have accomplished the AR coating other team will be in charge of designing the BEC apparatus

and use the results of our research

78

42 Experimentrsquos Equipment

421 Vacuum Chamber

For this research we designed a vacuum chamber whose main body is shown in figure 4-2 Its

dimensions are

Width 240 mm

Length 240 mm

Height 200 mm

Outer Diameter 4 in

Inner Diameter 15 in

Fig 4-2 Vacuum Chamber Main Body

The chamber is made up of 6 pass ways pass way A is the connection with the Laser Deposition

Equipment pass way B is the connection with the Turbo Pump and pass way C is for the connection with

the Deposition Source

A

C

B

79

Pass way C is for the deposition source as mentioned above This is a system where a thermal

resistance is heated by passing a high current through it which heats up a filament boat (made of tungsten)

where the material to be evaporated is place We control the temperature as such that the material will

evaporate and the heat will not cause the filament boat to crack

Because P = Isup2 R (where P is power I is current and R is resistance) to avoid the current to flow

where it is not desired we decided that the material for the Thermocouple shown in figure 4-3 should be

Copper ᴓ 63 mm We choose it that way because Copper has very good heat dissipation characteristics

and the resistance value is low It can reduce the value of the current enough to make the thermocouple to

create heat

Fig 4-3 Thermocouple

To the thermocouple we attach the tungsten filament boat We need to take notice of materials to be

used in this design because when using high current the tungsten filament boar will heat up and so the

material must be able to keep up with the heating potential of tungsten and has a low coefficient of heat

dissipation to avoid the tungsten to fail when heating up and therefore not evaporating Considering all

this we decide to use Stainless Steel

Because this clamp will be assembled inside the chamber after many revisions it was determined it

will have the shape shown in figure 4-4

Fig 4-4 Filament Boat Clamp Design

80

For the tungsten filament boat we bought the product from a distributor The dimensions are

Length 100 mm

Width 10 mm

Height 1 mm

Our thermocouple is 15 in but the pass way C is 4 in so we need to attach a Flange that connects

15in to 4in Because these specifications are quite difficult to achieve by Milling we had to use

electrical wire cutting

For the laser clamping system where the laser that is going to be AR coated will be placed will be

connected to pass way A the assembly is shown in figure 4-5 below

Fig 4-5 Cover Assembly

For this design we used an O-ring instead of a gasket so as to save time The design of the assembly

where the laser will be placed is shown in figure 4-6

Fig 4-6 Upper Cover Inner Assembly

D

E

F

81

Point D is the plate in the assembly where the laser diode will be fixed Because of the easy

processing we decide to use Aluminum and it is screwed to the top cover Point E is the connection for

the Quartz crystal resonator and it is designed in the same as point F in this way the results of the quartz

microbalance system will be more accurate in real time Point F is the final resting place for the laser

diode We use a Thor Labs Base with dimensions of ᴓ 9mm and ᴓ 56mm for two different size laser

diodes It just needs to be plugged in for easy installation

From figure 4-6 we know that the system needs signal system connections and because of the

change in temperature inside the chamber this could affect the functioning of the quartz microbalance so

we also need to install water tubes for cooling This is shown in figure 4-7 below

Fig 4-7 Diagram of Upper Cover Connections

In figure 4-8 we show the Feed through connections and their functions

Fig 4-8 Feed through Diagram

82

1 SQM-160 wire 5 Laser Connection 1 (Vin)

2 SQM-160 (G) 6 Laser Connection 2 (G)

3 K-Type-1 7 Laser Connection 3 (PD)

4 K-Type-2 8 Not In Use

The fully assembled chamber is shown in figure 4-9

Fig 4-9 Fully Assembled Chamber

422 Quartz Crystal Microbalance

For measuring the deposition on our target for coating we used the Inficon SQM-160 RateThickness

Monitor It is an easy to use instrument for measuring many types of thin-film coatings as shown in

figure 4-10

(a) Front Panel (b) Back Panel

Fig 4-10 Inficon SQM-160

83

Table 4-1 shows the technical specifications for this equipment

Number of sensors 2 Standard 4 additional optional

Sensor Frequency Range 40 MHz ~ 60 MHz

Reference Frequency Accuracy 002

Thickness Display Resolution 1 Aring

Thickness Resolution 015 Aring (Std) 0037 Aring (Hi Res)

Density of Stored Films 05-9999 gmcc

Tooling 10-399

Z-Factor 010-1000

Final Thickness 0000-9999k Aring

Measurement Period 15 to 2 sec

Simulation Mode Yes

Frequency Mode Yes

Rate Resolution 011 Arings

Dual Crystal Yes

Etch Mode Yes

Crystal Tooling 10-399

Crystal Fail Min Max 40 to 60 MHz 41 to 61 MHz

Power 100-120 200-240~plusmn10 nominal 20W

Operation Environment 0degC ~ 50degC

0 ~ 80 RH non-condensing

0 ~ 2000 meters

Class 1 Equipment

Pollution Degree 2

Rack Dimensions 885mm x 2127mm x 1969mm

Weight 27 kg

Table 4-1 Inficon SQM-160 RateThickness Monitor Specs

84

To the SQM-160 we need to connect an Oscillator We use the Sigma Instruments Remote Oscillator

Ser No 2 268 as shown in figure 4-11

Fig 4-11 Sigma Instruments Remote Oscillator

The connections diagram is shown in figure 4-12

Fig 4-12 SQM-160 Connections Diagram

85

423 Turbo Pump

For our experiments we used the Pfeiffer TCP 015 Electronic Drive Unit shown below in figure 4-13

Table 4-2 shows the technical specifications for this equipment

(a) Front Panel (b) Back Panel

Fig 4-13 Pfeiffer TCP 015 Electronic Drive

Connection Voltage (100V) 90-112

Mains Frequency 5060 Hz

Start-up Current 22 A

Nominal Frequency 1500 Hz

Rotation Speed 10V = 1500Hz plusmn2

Analog Output Current 10 V = 25 A plusmn 5

Rotation Speed Switchpoint 750 Hz

Works Setting 8 min

Permissible Ambient Temperature 0degC ~ 40degC

Dimensions Front Panel 1285mm x 1063mm

Insertion Length 227mm

Weight 27 Kg

Table 4-2 Pfeiffer TCP 015 Electronic Drive Specs

86

The connections diagram is shown in figure 4-14

Fig 4-14Connections Diagram for Pfeiffer TCP 015

To measure the pressure inside the chamber we use the Granville Phillips 375 Convectron Vacuum

Pressure Controller shown in figure 4-15

(a) Front Panel (b) Back Panel

Fig 4-15 Granville Phillips 375 Convectron

87

Its dimensions are shown in figure 4-16

Fig 4-16 Dimensions of Convectron

Table 4-3 shows the technical specifications for this equipment

Table 4-3 Granville Phillips 375 Convectron Vacuum Pressure Controller Specs

88

424 Multimeter

For our experiment we used the Keithley 2000 Digital Multimeter as shown in figure 4-17

(a) Front Panel (b) Back Panel

Fig 4-17 Keithley Model 2000 6-12-Digit Digital Multimeter

Its technical specifications are shown in table 4-4

Table 4-4 Keithley Model 2000 6-12-Digit Digital Multimeter Specs

89

43 Experiment Procedure

1 Connecting together the equipment and the chamber

(1) We first connect the resonator to the thickness monitor and connect the other side to the

chamber

(2) We now connect the flexible tubes to the turbo pump on one side and to the chamber on the

other

(3) We need to check that tubes are tightly connected to avoid any leaks in the vacuum pumping

process which will not allow us to get to our goal of Torr As shown in figure 4-18

(4) Connect the convectron to the system as shown in figure 4-19

Fig 4-18 checking for leaks using alcohol

Fig 4-19 Convectron attached to System

90

(5) Attach the clamps of the Multimeter to the bottom of the chamber as shown in figure 4-20

(6) Place the Quartz crystal in place

(7) Close tight vacuum chamber

(8) Connect all electrical appliances to power source

Fig 4-20 Multimeter Connections

2 Starting up the System

(1) We turn on all the devices as such Check all systems are ready to function Reset all values

that might be left over from previous tests

(2) Start the thickness monitor and set all values for this experiment In our case we got to testing

the system but not actual coating So we used the simulation mode of the thickness monitor as

shown in figure 4-21

Fig 4-21 Simulation Mode

91

(3) Start the turbo pump Make sure the lid on the vacuum chamber is tightly closed

(4) Start convectron and record initial pressure

(5) Start Multimeter and record initial current

3 Coating Process

(1) If we have the deposition material inside the filament boat the power source for the high

current must be started as well

(2) Record all initial values for thickness current pressure

(3) For an ideal experiment we need a thickness of around 101 nm a pressure of Torr and

a current of 300 A

44 Results

From previous experiments we have shown that we can turn a LED into a laser by means of AR

Coating In figure 4-22 shown below we can compare the actual results of a Diode before and after AR

coating From the blue line we can see that when the diode is at a current of 15mA its light will change

from LED to laser and if we look at the red line its critical current is around 30 to 35 mA

Fig 4-22 AR Coating Comparison for Laser Diodes

This means that the light emitted is not as strong as if the diode had been coated because inside the

chamber there must be some excitation first so the reflectivity of both sides inside the diode must be high

So because of the coating in one of the sides we have opened a door and let the light come out so the

critical current is risen as such and will be higher value than that of before the coating

92

In the following figures we can see the difference between before and after coating in a material The

thickness is around 1016 nm for this material

Fig 4-23 Before Coating

Fig 4-24 After Coating

93

Chapter 5 CONCLUSIONS AND RECOMMENDATIONS

51 Conclusions

For the first part of this independent study taking into consideration the data that came out of our

research and that sent by the provider we can say

1 SUM 23 after heat treatment will unexpectedly develop cracking in the middle of the tensile

testing process and suddenly break

2 Itrsquos possible that in the process of heat treatment to the SUM 23 material the treatment was not

uniform and this will create a pre-loaded moment force on one side that pushes on the other side

of the specimen resulting in material deformation

3 In the process of attaching the strain gauges to the materials it is very easy to make errors due to

poor adhesion or sudden removal in the tensile testing process

For our second part of the independent study the following can be made

1 At the beginning of this independent study we had no idea what Bose-Einstein Condensate was

or what was its purpose After much literature we finally comprehended the basic principles to

put into practice for our research

2 Our systemrsquos basic working principles and equipmentrsquos complexity are a little difficult to grasp

but hopefully we were able to understand enough of it

3 Theoretically from relation between the power and current we can know the advantages and

disadvantages of AR Coating

4 We were able to assemble the system and run test on its functions Even though we were able to

do this there is still much more work left to do with this system

52 Recommendations

For the Tensile Testing the following can be said

1 Ask the provider to check on the process of heat treatment on the SUM 23 material and give

them the information we have gathered through our test so they can correct for the mechanical

properties found if any change is needed

2 To avoid the problem of the inaccuracy of the poor adhesion of strain gauges we can attach

multiple strain gauges to the same one specimen so as to correlate data and improve our results

For the AR Coating the following can be said

1 We need to make sure that there are no physical defects on the main body of the chamber so as to

achieve maximum efficiency in the vacuum process If there was then the vacuum will arrive to

certain point and then start to decrease

2 It would be preferable to add some sort of visual aid that will allow the user to check the inside of

the chamber without actually opening it This will help us determine at what times we should

manipulate the current to better evaporate the substrate

94

REFERENCES

[1] A L Window Strain Gauge Technology Elsevier Applied Science London and New York 2nd

Edition 1992

[2] CC Perry and HR Lissner Strain Gauge Primer McGraw-Hill Book Co Inc New York 1955

[3] James W Dally William F Riley McGraw-Hill 1978

[4] University of Colorado Boulder BEC - What is it and where did the idea come from

httpwwwcoloradoeduphysics2000becwhat_is_ithtml

[5] Ultraslow Light amp Bose-Einstein Condensates Two-way Control with Coherent Light amp Atom

Fields Harvard Hau Lab Dr Lene Vestergaard Hau Optics amp Photonics News 16 1995

[6] The Art of Taming Light Ultra-slow and Stopped Light Harvard Hau Lab Dr Lene

Vestergaard Hau Europhysics News 2004

[7] Nonlinear Optics Shocking Superfluids Harvard Hau Lab Dr Lene Vestergaard Hau Nature

Physics 2007

[8] Model P3 Strain Indicator and Recorder Instruction Manual Vishay Micro-Measurements 2005

[9] Granville-Phillips Series 375 Convectron Vacuum Gauge Controller Instruction Manual Brooks

Automation 2008

[10] Effect of Film Thickness on the Validity of the Sauerbrey Equation for Hydrated Polyelectrolyte

Films Vogt Lin Wu White 2004

[11] Quartz Crystal Microbalance Study of DNA Immobilization and Hybridization for DNA Sensor

Development Chang Zhao 2008

[12] Installation of Strain Gages with SR-4 PrecoatAdhesive Vishay Micro-Measurements 2005

[13] Strain Gauge Measurement ndash A Tutorial National Instruments 1998

[14] Correlation between Vickers Hardness Number and Yield Stress of Cold-Formed Products

Yavuz Tekkaya

[15] httpsenwikipediaorg

Page 49: PC Hinge Materials Testing and AR Laser Diode Coating

49

(a)

(2) Use alcohol to wash the surface where the strain gauge will be attached and use gauze to rub

it off

(b)

(3) Find a clean surface and clean it with alcohol and gauze

(c)

(4) Place the strain gauge in the clean surface Use a piece of transparent tape on top of the strain

gauge after securely placed rip it off the surface carefully

50

(d)

(5) Use a piece of white paper to mark the place where the strain gauge will be attached and in

this way we can make sure that the strain gauge will be placed as horizontally and vertically

correct as possible

(e)

(6) In the place where we had our mark place the strain gauge

(f)

(7) Carefully lift one side of the tape and apply some of the adhesive agent to both the strain

gauge and specimenrsquos surface

(g)

51

(8) We need to make sure that the gauge and the specimen will be firmly attached so we gently

apply pressure with our thumb

(h)

(9) After the adhesive is fully dry we can carefully rip off the tape

(i)

(10) We need to do the whole process twice one for the horizontally placed strain gauge and one

for the vertically placed strain gauge

52

(j)

(11) We now proceed to solder the wires to the strain gauge

(k)

(12) After soldering we use a Volt Multimeter to measure that there is no contact between wires

If there is none then the specimen is ready for testing

(l)

(13) We now need to measure a 5cm distance and mark it to check and compare the elongation

before and after the tensile testing

(m)

53

Fig 3-9 Specimen-Strain Gauge Process

3 Tensile Test

(1) Enter the computer application that controls the tensile testing machine

(2) Turn on the tensile testing machine main switch

(3) Adjust the hydraulic pump to go back to its original position

(4) Bring the lowering motor down to a distance enough so as to attach the tensile specimen to the

system open the clamps and secure the specimen

(a)

(5) Connect all the necessary wires to the strain indicator equipment

54

(b)

(6) Start the ascending motor and wait for the expansion

(c)

Fig 3-10 Specimen-Tensile Testing Process

4 Start the Test

(1) Enter the software application and enter some variables needed for the experiment in the

specific screen

(2) Go back to the main screen and press the [測試] (measure) button to start the test and auto

recording in the software

(3) After the specimen breaks the mechanical device will automatically stop and ask the user to

enter the total displacement We take out the specimen from the testing machine and adjust the

machinersquos position back to its original position

(4) Save the results information

(5) Record the results from the strain indicator

34 Results

From this experiment we can get the Poissonrsquos Ratio Youngrsquos Modulus and Yield Strength etc and

because of the slippage phenomenon in the clamp at the moment of the test then the Elastic Limit will

display some yield phenomena So omit any undesirable results we just take the Yield portion of the

results as reference

In the process of the experiment the most important part to attend to is the attaching of the strain

gauge because the gaugersquos purpose is to measure the strain developed during the test and this strain

might be very small If the gaugersquos angle change during the test ie is not well attached this will affect

the accuracy of the measurements of Poissonrsquos ratio and Youngrsquos modulus

55

The materials provided by the manufacturer are SUM 23 and SUM 43 steel round bars and these two

types of materials have been through different heat treatment processes so they can be sub-divided

further into untreated material heat-treated material and black surface heat treated material for the two

materials with heat treatment the treatment process and finished are different In the end we only have

the mechanical properties that were calculated after our research of these materials

All of the specifications are identical to those shown in figure 3-6

341 SUM 23

Fig 3-11 SUM 23 Untreated Material

Number 7 10

Hardness(HRB) 74 75

Yield Stress (MPa) 448 440

Tensile Strength (MPa) 544 560

Poissonrsquos Ratio 029 027

Youngrsquos Modulus (GPa) 203 210

Cut-off Area Shrinking () 42 41

Elongation () 1125 1011

Table 3-5 Mechanical Properties of SUM 23 Untreated

56

Stress-Strain Diagram

(a)

(b)

57

Fig 3-12 Stress-Strain Diagrams for (a) 7 Round Bar and (b) 10 Round Bar

Cut-Off Area

(a)

(b)

Fig 3-13 Cut-Off Area of (a) 7 Round Bar and (b) 10 Round Bar

58

SUM 23 Nickel Round Bar

Fig 3-14 SUM 23 Nickel Material

Number 1 2 3 4

Hardness(HRB) 48 50 49 48

Yield Stress (MPa) 370 370 380 400

Tensile Strength (MPa) 455 451 450 450

Poissonrsquos Ratio 028 046 029 026

Youngrsquos Modulus (GPa) 243 303 246 206

Cut-off Area Shrinking () 803 803 726 601

Elongation () 566 65 602 647

Table 3-6 Mechanical Properties of SUM 23 Nickel

59

Stress-Strain Diagram

(a)

60

(b)

(c)

(d)

61

Fig 3-15 Stress-Strain Diagrams for (a) 1 Round Bar (b) 2 Round Bar (c) 3 Round Bar and (d)

4 Round Bar

Cut-Off Area

(a)

(b)

62

(c)

(d)

Fig 3-16 Cut-Off Area of (a) 1 Round Bar (b) 2 Round Bar (c) 3 Round Bar and (d) 4 Round

Bar

63

SUM 23 Black Surface Round Bar

Fig 3-17 SUM 23 Black Surface Material

Number 1 2 3

Hardness(HRB) 51 50 51

Yield Stress (MPa) 378 371 369

Tensile Strength (MPa) 467 465 464

Poissonrsquos Ratio 03 016 04

Youngrsquos Modulus (GPa) 215 266 266

Cut-off Area Shrinking () 986 94 848

Elongation () 748 805 761

Table 3-7 Mechanical Properties of SUM 23 Black Surface Material

64

Stress-Strain Diagram

(a)

(b)

65

(c)

Fig 3-18 Stress-Strain Diagrams for (a) 1 Round Bar 2 Round Bar and (c) 3 Round Bar

Cut-Off Surface

(a)

66

(b)

(c)

Fig 3-19 Cut-Off Surface of (a) 1 Round Bar 2 Round Bar and (c) 3 Round Bar

67

342 SUM 43

Fig 3-20 Untreated SUM 43 Untreated Material

Number 1 5

Hardness(HRB) 76 75

Yield Stress (MPa) 572 594

Tensile Strength (MPa) 743 785

Poissonrsquos Ratio 027 029

Youngrsquos Modulus (GPa) 200 202

Cut-off Area Shrinking () 338 2944

Elongation () 857 894

Table 3-8 Mechanical Properties of SUM 43 Untreated

68

Stress-Strain Diagrams

(a)

(b)

Fig 3-21 Stress-Strain Diagrams for SUM 43 (a) 1 Round Bar and (b) 5 Round Bar

69

Cut-Off Area

(a)

(b)

Fig 3-22 Cut-Off Area of SUM 43 (a) 1 Round Bar and (b) 5 Round Bar

70

SUM 43 Nickel Round Bar

Fig 3-23 SUM 43 Nickel Material

Number 4 5

Hardness(HRB) 51 50

Yield Stress (MPa) 1580 1544

Tensile Strength (MPa) 1639 1625

Poissonrsquos Ratio 03 028

Youngrsquos Modulus (GPa) 194 201

Cut-off Area Shrinking () 1697 137

Elongation () 376 265

Table 3-9 Mechanical Properties of SUM 43 Nickel

71

Stress-Strain Diagrams

(a)

(b)

Fig 3-24 Stress-Strain Diagrams for (a) 4 Round Bar and (b) 5 Round Bar

72

Cut-Off Area

(a)

(b)

Fig 3-25 Cut-Off Area of (a) 4 Round Bar and (b) 5 Round Bar

73

SUM 43 Black Surface Material

Fig 3-26 SUM 43 Black Surface Material

Number 3 5

Hardness(HRB) 56 56

Yield Stress (MPa) 1416 1361

Tensile Strength (MPa) 1591 1402

Poissonrsquos Ratio 029 031

Youngrsquos Modulus (GPa) 200 202

Cut-off Area Shrinking () 139 124

Elongation () 24 24

Table 3-10 Mechanical Properties of SUM 43 Black Surface Material

74

Stress-Strain Diagrams

0 2 4 6 8 10 12 14

-200

0

200

400

600

800

1000

1200

1400

1600

1800

應力 (MPa)

應變()

(a)

0 2 4 6 8 10

-200

0

200

400

600

800

1000

1200

1400

1600

應力

(MPa)

位移 ()

(b)

Fig 3-27 Stress-Strain Diagrams for (a) 3 Round Bar and (b) 5 Round Bar

(Note These curves were formulated using Visual Solutions Inc VisSim Software)

75

Cut-Off Area

(a)

(b)

Fig 3-28 Cut-Off Area of (a) 3 Round Bar and (b) 5 Round Bar

76

The force value (N) was retrieved from the Universal Testing Machine

The Poissonrsquos Ratio (ε) is calculated as

ε =

the values for the Poissonrsquos Ratio are in average around 0297

The Youngrsquos Modulus (E) is calculated as

E =

Where

Stress =

Cross-sectional Area =

where D is the Diameter

The value for D was in average around 1258 mm

The values shown by the computer because there is Slippage phenomena between the Clamp and the

specimen will not be taken into consideration for the elongation strain and Youngrsquos modulus and we will

refer to the values that we have meticulously calculated

77

Chapter 4 AR COATING IN DEPTH

41 Experimentrsquos Purpose and Principles

By means of a vacuum chamber and several other instruments we intend to apply Anti-Reflective

Coating using deposition process to a laser diode and in this way reduce its refraction so as to make it

lose less light in the process of amplification and we can control certain wavelengths we want produced

for certain desired applications in our case we are attempting to re-create a Bose-Einstein Condensate

An optimal BEC apparatus is shown in figure 4-1

Fig 4-1 BEC Apparatus

The main point of this experiment is to build a vacuum chamber system attach all the instrumentation

needed (Vacuum pump deposition meter and voltmeter) and use it to apply AR coating to a laser diode

After we have accomplished the AR coating other team will be in charge of designing the BEC apparatus

and use the results of our research

78

42 Experimentrsquos Equipment

421 Vacuum Chamber

For this research we designed a vacuum chamber whose main body is shown in figure 4-2 Its

dimensions are

Width 240 mm

Length 240 mm

Height 200 mm

Outer Diameter 4 in

Inner Diameter 15 in

Fig 4-2 Vacuum Chamber Main Body

The chamber is made up of 6 pass ways pass way A is the connection with the Laser Deposition

Equipment pass way B is the connection with the Turbo Pump and pass way C is for the connection with

the Deposition Source

A

C

B

79

Pass way C is for the deposition source as mentioned above This is a system where a thermal

resistance is heated by passing a high current through it which heats up a filament boat (made of tungsten)

where the material to be evaporated is place We control the temperature as such that the material will

evaporate and the heat will not cause the filament boat to crack

Because P = Isup2 R (where P is power I is current and R is resistance) to avoid the current to flow

where it is not desired we decided that the material for the Thermocouple shown in figure 4-3 should be

Copper ᴓ 63 mm We choose it that way because Copper has very good heat dissipation characteristics

and the resistance value is low It can reduce the value of the current enough to make the thermocouple to

create heat

Fig 4-3 Thermocouple

To the thermocouple we attach the tungsten filament boat We need to take notice of materials to be

used in this design because when using high current the tungsten filament boar will heat up and so the

material must be able to keep up with the heating potential of tungsten and has a low coefficient of heat

dissipation to avoid the tungsten to fail when heating up and therefore not evaporating Considering all

this we decide to use Stainless Steel

Because this clamp will be assembled inside the chamber after many revisions it was determined it

will have the shape shown in figure 4-4

Fig 4-4 Filament Boat Clamp Design

80

For the tungsten filament boat we bought the product from a distributor The dimensions are

Length 100 mm

Width 10 mm

Height 1 mm

Our thermocouple is 15 in but the pass way C is 4 in so we need to attach a Flange that connects

15in to 4in Because these specifications are quite difficult to achieve by Milling we had to use

electrical wire cutting

For the laser clamping system where the laser that is going to be AR coated will be placed will be

connected to pass way A the assembly is shown in figure 4-5 below

Fig 4-5 Cover Assembly

For this design we used an O-ring instead of a gasket so as to save time The design of the assembly

where the laser will be placed is shown in figure 4-6

Fig 4-6 Upper Cover Inner Assembly

D

E

F

81

Point D is the plate in the assembly where the laser diode will be fixed Because of the easy

processing we decide to use Aluminum and it is screwed to the top cover Point E is the connection for

the Quartz crystal resonator and it is designed in the same as point F in this way the results of the quartz

microbalance system will be more accurate in real time Point F is the final resting place for the laser

diode We use a Thor Labs Base with dimensions of ᴓ 9mm and ᴓ 56mm for two different size laser

diodes It just needs to be plugged in for easy installation

From figure 4-6 we know that the system needs signal system connections and because of the

change in temperature inside the chamber this could affect the functioning of the quartz microbalance so

we also need to install water tubes for cooling This is shown in figure 4-7 below

Fig 4-7 Diagram of Upper Cover Connections

In figure 4-8 we show the Feed through connections and their functions

Fig 4-8 Feed through Diagram

82

1 SQM-160 wire 5 Laser Connection 1 (Vin)

2 SQM-160 (G) 6 Laser Connection 2 (G)

3 K-Type-1 7 Laser Connection 3 (PD)

4 K-Type-2 8 Not In Use

The fully assembled chamber is shown in figure 4-9

Fig 4-9 Fully Assembled Chamber

422 Quartz Crystal Microbalance

For measuring the deposition on our target for coating we used the Inficon SQM-160 RateThickness

Monitor It is an easy to use instrument for measuring many types of thin-film coatings as shown in

figure 4-10

(a) Front Panel (b) Back Panel

Fig 4-10 Inficon SQM-160

83

Table 4-1 shows the technical specifications for this equipment

Number of sensors 2 Standard 4 additional optional

Sensor Frequency Range 40 MHz ~ 60 MHz

Reference Frequency Accuracy 002

Thickness Display Resolution 1 Aring

Thickness Resolution 015 Aring (Std) 0037 Aring (Hi Res)

Density of Stored Films 05-9999 gmcc

Tooling 10-399

Z-Factor 010-1000

Final Thickness 0000-9999k Aring

Measurement Period 15 to 2 sec

Simulation Mode Yes

Frequency Mode Yes

Rate Resolution 011 Arings

Dual Crystal Yes

Etch Mode Yes

Crystal Tooling 10-399

Crystal Fail Min Max 40 to 60 MHz 41 to 61 MHz

Power 100-120 200-240~plusmn10 nominal 20W

Operation Environment 0degC ~ 50degC

0 ~ 80 RH non-condensing

0 ~ 2000 meters

Class 1 Equipment

Pollution Degree 2

Rack Dimensions 885mm x 2127mm x 1969mm

Weight 27 kg

Table 4-1 Inficon SQM-160 RateThickness Monitor Specs

84

To the SQM-160 we need to connect an Oscillator We use the Sigma Instruments Remote Oscillator

Ser No 2 268 as shown in figure 4-11

Fig 4-11 Sigma Instruments Remote Oscillator

The connections diagram is shown in figure 4-12

Fig 4-12 SQM-160 Connections Diagram

85

423 Turbo Pump

For our experiments we used the Pfeiffer TCP 015 Electronic Drive Unit shown below in figure 4-13

Table 4-2 shows the technical specifications for this equipment

(a) Front Panel (b) Back Panel

Fig 4-13 Pfeiffer TCP 015 Electronic Drive

Connection Voltage (100V) 90-112

Mains Frequency 5060 Hz

Start-up Current 22 A

Nominal Frequency 1500 Hz

Rotation Speed 10V = 1500Hz plusmn2

Analog Output Current 10 V = 25 A plusmn 5

Rotation Speed Switchpoint 750 Hz

Works Setting 8 min

Permissible Ambient Temperature 0degC ~ 40degC

Dimensions Front Panel 1285mm x 1063mm

Insertion Length 227mm

Weight 27 Kg

Table 4-2 Pfeiffer TCP 015 Electronic Drive Specs

86

The connections diagram is shown in figure 4-14

Fig 4-14Connections Diagram for Pfeiffer TCP 015

To measure the pressure inside the chamber we use the Granville Phillips 375 Convectron Vacuum

Pressure Controller shown in figure 4-15

(a) Front Panel (b) Back Panel

Fig 4-15 Granville Phillips 375 Convectron

87

Its dimensions are shown in figure 4-16

Fig 4-16 Dimensions of Convectron

Table 4-3 shows the technical specifications for this equipment

Table 4-3 Granville Phillips 375 Convectron Vacuum Pressure Controller Specs

88

424 Multimeter

For our experiment we used the Keithley 2000 Digital Multimeter as shown in figure 4-17

(a) Front Panel (b) Back Panel

Fig 4-17 Keithley Model 2000 6-12-Digit Digital Multimeter

Its technical specifications are shown in table 4-4

Table 4-4 Keithley Model 2000 6-12-Digit Digital Multimeter Specs

89

43 Experiment Procedure

1 Connecting together the equipment and the chamber

(1) We first connect the resonator to the thickness monitor and connect the other side to the

chamber

(2) We now connect the flexible tubes to the turbo pump on one side and to the chamber on the

other

(3) We need to check that tubes are tightly connected to avoid any leaks in the vacuum pumping

process which will not allow us to get to our goal of Torr As shown in figure 4-18

(4) Connect the convectron to the system as shown in figure 4-19

Fig 4-18 checking for leaks using alcohol

Fig 4-19 Convectron attached to System

90

(5) Attach the clamps of the Multimeter to the bottom of the chamber as shown in figure 4-20

(6) Place the Quartz crystal in place

(7) Close tight vacuum chamber

(8) Connect all electrical appliances to power source

Fig 4-20 Multimeter Connections

2 Starting up the System

(1) We turn on all the devices as such Check all systems are ready to function Reset all values

that might be left over from previous tests

(2) Start the thickness monitor and set all values for this experiment In our case we got to testing

the system but not actual coating So we used the simulation mode of the thickness monitor as

shown in figure 4-21

Fig 4-21 Simulation Mode

91

(3) Start the turbo pump Make sure the lid on the vacuum chamber is tightly closed

(4) Start convectron and record initial pressure

(5) Start Multimeter and record initial current

3 Coating Process

(1) If we have the deposition material inside the filament boat the power source for the high

current must be started as well

(2) Record all initial values for thickness current pressure

(3) For an ideal experiment we need a thickness of around 101 nm a pressure of Torr and

a current of 300 A

44 Results

From previous experiments we have shown that we can turn a LED into a laser by means of AR

Coating In figure 4-22 shown below we can compare the actual results of a Diode before and after AR

coating From the blue line we can see that when the diode is at a current of 15mA its light will change

from LED to laser and if we look at the red line its critical current is around 30 to 35 mA

Fig 4-22 AR Coating Comparison for Laser Diodes

This means that the light emitted is not as strong as if the diode had been coated because inside the

chamber there must be some excitation first so the reflectivity of both sides inside the diode must be high

So because of the coating in one of the sides we have opened a door and let the light come out so the

critical current is risen as such and will be higher value than that of before the coating

92

In the following figures we can see the difference between before and after coating in a material The

thickness is around 1016 nm for this material

Fig 4-23 Before Coating

Fig 4-24 After Coating

93

Chapter 5 CONCLUSIONS AND RECOMMENDATIONS

51 Conclusions

For the first part of this independent study taking into consideration the data that came out of our

research and that sent by the provider we can say

1 SUM 23 after heat treatment will unexpectedly develop cracking in the middle of the tensile

testing process and suddenly break

2 Itrsquos possible that in the process of heat treatment to the SUM 23 material the treatment was not

uniform and this will create a pre-loaded moment force on one side that pushes on the other side

of the specimen resulting in material deformation

3 In the process of attaching the strain gauges to the materials it is very easy to make errors due to

poor adhesion or sudden removal in the tensile testing process

For our second part of the independent study the following can be made

1 At the beginning of this independent study we had no idea what Bose-Einstein Condensate was

or what was its purpose After much literature we finally comprehended the basic principles to

put into practice for our research

2 Our systemrsquos basic working principles and equipmentrsquos complexity are a little difficult to grasp

but hopefully we were able to understand enough of it

3 Theoretically from relation between the power and current we can know the advantages and

disadvantages of AR Coating

4 We were able to assemble the system and run test on its functions Even though we were able to

do this there is still much more work left to do with this system

52 Recommendations

For the Tensile Testing the following can be said

1 Ask the provider to check on the process of heat treatment on the SUM 23 material and give

them the information we have gathered through our test so they can correct for the mechanical

properties found if any change is needed

2 To avoid the problem of the inaccuracy of the poor adhesion of strain gauges we can attach

multiple strain gauges to the same one specimen so as to correlate data and improve our results

For the AR Coating the following can be said

1 We need to make sure that there are no physical defects on the main body of the chamber so as to

achieve maximum efficiency in the vacuum process If there was then the vacuum will arrive to

certain point and then start to decrease

2 It would be preferable to add some sort of visual aid that will allow the user to check the inside of

the chamber without actually opening it This will help us determine at what times we should

manipulate the current to better evaporate the substrate

94

REFERENCES

[1] A L Window Strain Gauge Technology Elsevier Applied Science London and New York 2nd

Edition 1992

[2] CC Perry and HR Lissner Strain Gauge Primer McGraw-Hill Book Co Inc New York 1955

[3] James W Dally William F Riley McGraw-Hill 1978

[4] University of Colorado Boulder BEC - What is it and where did the idea come from

httpwwwcoloradoeduphysics2000becwhat_is_ithtml

[5] Ultraslow Light amp Bose-Einstein Condensates Two-way Control with Coherent Light amp Atom

Fields Harvard Hau Lab Dr Lene Vestergaard Hau Optics amp Photonics News 16 1995

[6] The Art of Taming Light Ultra-slow and Stopped Light Harvard Hau Lab Dr Lene

Vestergaard Hau Europhysics News 2004

[7] Nonlinear Optics Shocking Superfluids Harvard Hau Lab Dr Lene Vestergaard Hau Nature

Physics 2007

[8] Model P3 Strain Indicator and Recorder Instruction Manual Vishay Micro-Measurements 2005

[9] Granville-Phillips Series 375 Convectron Vacuum Gauge Controller Instruction Manual Brooks

Automation 2008

[10] Effect of Film Thickness on the Validity of the Sauerbrey Equation for Hydrated Polyelectrolyte

Films Vogt Lin Wu White 2004

[11] Quartz Crystal Microbalance Study of DNA Immobilization and Hybridization for DNA Sensor

Development Chang Zhao 2008

[12] Installation of Strain Gages with SR-4 PrecoatAdhesive Vishay Micro-Measurements 2005

[13] Strain Gauge Measurement ndash A Tutorial National Instruments 1998

[14] Correlation between Vickers Hardness Number and Yield Stress of Cold-Formed Products

Yavuz Tekkaya

[15] httpsenwikipediaorg

Page 50: PC Hinge Materials Testing and AR Laser Diode Coating

50

(d)

(5) Use a piece of white paper to mark the place where the strain gauge will be attached and in

this way we can make sure that the strain gauge will be placed as horizontally and vertically

correct as possible

(e)

(6) In the place where we had our mark place the strain gauge

(f)

(7) Carefully lift one side of the tape and apply some of the adhesive agent to both the strain

gauge and specimenrsquos surface

(g)

51

(8) We need to make sure that the gauge and the specimen will be firmly attached so we gently

apply pressure with our thumb

(h)

(9) After the adhesive is fully dry we can carefully rip off the tape

(i)

(10) We need to do the whole process twice one for the horizontally placed strain gauge and one

for the vertically placed strain gauge

52

(j)

(11) We now proceed to solder the wires to the strain gauge

(k)

(12) After soldering we use a Volt Multimeter to measure that there is no contact between wires

If there is none then the specimen is ready for testing

(l)

(13) We now need to measure a 5cm distance and mark it to check and compare the elongation

before and after the tensile testing

(m)

53

Fig 3-9 Specimen-Strain Gauge Process

3 Tensile Test

(1) Enter the computer application that controls the tensile testing machine

(2) Turn on the tensile testing machine main switch

(3) Adjust the hydraulic pump to go back to its original position

(4) Bring the lowering motor down to a distance enough so as to attach the tensile specimen to the

system open the clamps and secure the specimen

(a)

(5) Connect all the necessary wires to the strain indicator equipment

54

(b)

(6) Start the ascending motor and wait for the expansion

(c)

Fig 3-10 Specimen-Tensile Testing Process

4 Start the Test

(1) Enter the software application and enter some variables needed for the experiment in the

specific screen

(2) Go back to the main screen and press the [測試] (measure) button to start the test and auto

recording in the software

(3) After the specimen breaks the mechanical device will automatically stop and ask the user to

enter the total displacement We take out the specimen from the testing machine and adjust the

machinersquos position back to its original position

(4) Save the results information

(5) Record the results from the strain indicator

34 Results

From this experiment we can get the Poissonrsquos Ratio Youngrsquos Modulus and Yield Strength etc and

because of the slippage phenomenon in the clamp at the moment of the test then the Elastic Limit will

display some yield phenomena So omit any undesirable results we just take the Yield portion of the

results as reference

In the process of the experiment the most important part to attend to is the attaching of the strain

gauge because the gaugersquos purpose is to measure the strain developed during the test and this strain

might be very small If the gaugersquos angle change during the test ie is not well attached this will affect

the accuracy of the measurements of Poissonrsquos ratio and Youngrsquos modulus

55

The materials provided by the manufacturer are SUM 23 and SUM 43 steel round bars and these two

types of materials have been through different heat treatment processes so they can be sub-divided

further into untreated material heat-treated material and black surface heat treated material for the two

materials with heat treatment the treatment process and finished are different In the end we only have

the mechanical properties that were calculated after our research of these materials

All of the specifications are identical to those shown in figure 3-6

341 SUM 23

Fig 3-11 SUM 23 Untreated Material

Number 7 10

Hardness(HRB) 74 75

Yield Stress (MPa) 448 440

Tensile Strength (MPa) 544 560

Poissonrsquos Ratio 029 027

Youngrsquos Modulus (GPa) 203 210

Cut-off Area Shrinking () 42 41

Elongation () 1125 1011

Table 3-5 Mechanical Properties of SUM 23 Untreated

56

Stress-Strain Diagram

(a)

(b)

57

Fig 3-12 Stress-Strain Diagrams for (a) 7 Round Bar and (b) 10 Round Bar

Cut-Off Area

(a)

(b)

Fig 3-13 Cut-Off Area of (a) 7 Round Bar and (b) 10 Round Bar

58

SUM 23 Nickel Round Bar

Fig 3-14 SUM 23 Nickel Material

Number 1 2 3 4

Hardness(HRB) 48 50 49 48

Yield Stress (MPa) 370 370 380 400

Tensile Strength (MPa) 455 451 450 450

Poissonrsquos Ratio 028 046 029 026

Youngrsquos Modulus (GPa) 243 303 246 206

Cut-off Area Shrinking () 803 803 726 601

Elongation () 566 65 602 647

Table 3-6 Mechanical Properties of SUM 23 Nickel

59

Stress-Strain Diagram

(a)

60

(b)

(c)

(d)

61

Fig 3-15 Stress-Strain Diagrams for (a) 1 Round Bar (b) 2 Round Bar (c) 3 Round Bar and (d)

4 Round Bar

Cut-Off Area

(a)

(b)

62

(c)

(d)

Fig 3-16 Cut-Off Area of (a) 1 Round Bar (b) 2 Round Bar (c) 3 Round Bar and (d) 4 Round

Bar

63

SUM 23 Black Surface Round Bar

Fig 3-17 SUM 23 Black Surface Material

Number 1 2 3

Hardness(HRB) 51 50 51

Yield Stress (MPa) 378 371 369

Tensile Strength (MPa) 467 465 464

Poissonrsquos Ratio 03 016 04

Youngrsquos Modulus (GPa) 215 266 266

Cut-off Area Shrinking () 986 94 848

Elongation () 748 805 761

Table 3-7 Mechanical Properties of SUM 23 Black Surface Material

64

Stress-Strain Diagram

(a)

(b)

65

(c)

Fig 3-18 Stress-Strain Diagrams for (a) 1 Round Bar 2 Round Bar and (c) 3 Round Bar

Cut-Off Surface

(a)

66

(b)

(c)

Fig 3-19 Cut-Off Surface of (a) 1 Round Bar 2 Round Bar and (c) 3 Round Bar

67

342 SUM 43

Fig 3-20 Untreated SUM 43 Untreated Material

Number 1 5

Hardness(HRB) 76 75

Yield Stress (MPa) 572 594

Tensile Strength (MPa) 743 785

Poissonrsquos Ratio 027 029

Youngrsquos Modulus (GPa) 200 202

Cut-off Area Shrinking () 338 2944

Elongation () 857 894

Table 3-8 Mechanical Properties of SUM 43 Untreated

68

Stress-Strain Diagrams

(a)

(b)

Fig 3-21 Stress-Strain Diagrams for SUM 43 (a) 1 Round Bar and (b) 5 Round Bar

69

Cut-Off Area

(a)

(b)

Fig 3-22 Cut-Off Area of SUM 43 (a) 1 Round Bar and (b) 5 Round Bar

70

SUM 43 Nickel Round Bar

Fig 3-23 SUM 43 Nickel Material

Number 4 5

Hardness(HRB) 51 50

Yield Stress (MPa) 1580 1544

Tensile Strength (MPa) 1639 1625

Poissonrsquos Ratio 03 028

Youngrsquos Modulus (GPa) 194 201

Cut-off Area Shrinking () 1697 137

Elongation () 376 265

Table 3-9 Mechanical Properties of SUM 43 Nickel

71

Stress-Strain Diagrams

(a)

(b)

Fig 3-24 Stress-Strain Diagrams for (a) 4 Round Bar and (b) 5 Round Bar

72

Cut-Off Area

(a)

(b)

Fig 3-25 Cut-Off Area of (a) 4 Round Bar and (b) 5 Round Bar

73

SUM 43 Black Surface Material

Fig 3-26 SUM 43 Black Surface Material

Number 3 5

Hardness(HRB) 56 56

Yield Stress (MPa) 1416 1361

Tensile Strength (MPa) 1591 1402

Poissonrsquos Ratio 029 031

Youngrsquos Modulus (GPa) 200 202

Cut-off Area Shrinking () 139 124

Elongation () 24 24

Table 3-10 Mechanical Properties of SUM 43 Black Surface Material

74

Stress-Strain Diagrams

0 2 4 6 8 10 12 14

-200

0

200

400

600

800

1000

1200

1400

1600

1800

應力 (MPa)

應變()

(a)

0 2 4 6 8 10

-200

0

200

400

600

800

1000

1200

1400

1600

應力

(MPa)

位移 ()

(b)

Fig 3-27 Stress-Strain Diagrams for (a) 3 Round Bar and (b) 5 Round Bar

(Note These curves were formulated using Visual Solutions Inc VisSim Software)

75

Cut-Off Area

(a)

(b)

Fig 3-28 Cut-Off Area of (a) 3 Round Bar and (b) 5 Round Bar

76

The force value (N) was retrieved from the Universal Testing Machine

The Poissonrsquos Ratio (ε) is calculated as

ε =

the values for the Poissonrsquos Ratio are in average around 0297

The Youngrsquos Modulus (E) is calculated as

E =

Where

Stress =

Cross-sectional Area =

where D is the Diameter

The value for D was in average around 1258 mm

The values shown by the computer because there is Slippage phenomena between the Clamp and the

specimen will not be taken into consideration for the elongation strain and Youngrsquos modulus and we will

refer to the values that we have meticulously calculated

77

Chapter 4 AR COATING IN DEPTH

41 Experimentrsquos Purpose and Principles

By means of a vacuum chamber and several other instruments we intend to apply Anti-Reflective

Coating using deposition process to a laser diode and in this way reduce its refraction so as to make it

lose less light in the process of amplification and we can control certain wavelengths we want produced

for certain desired applications in our case we are attempting to re-create a Bose-Einstein Condensate

An optimal BEC apparatus is shown in figure 4-1

Fig 4-1 BEC Apparatus

The main point of this experiment is to build a vacuum chamber system attach all the instrumentation

needed (Vacuum pump deposition meter and voltmeter) and use it to apply AR coating to a laser diode

After we have accomplished the AR coating other team will be in charge of designing the BEC apparatus

and use the results of our research

78

42 Experimentrsquos Equipment

421 Vacuum Chamber

For this research we designed a vacuum chamber whose main body is shown in figure 4-2 Its

dimensions are

Width 240 mm

Length 240 mm

Height 200 mm

Outer Diameter 4 in

Inner Diameter 15 in

Fig 4-2 Vacuum Chamber Main Body

The chamber is made up of 6 pass ways pass way A is the connection with the Laser Deposition

Equipment pass way B is the connection with the Turbo Pump and pass way C is for the connection with

the Deposition Source

A

C

B

79

Pass way C is for the deposition source as mentioned above This is a system where a thermal

resistance is heated by passing a high current through it which heats up a filament boat (made of tungsten)

where the material to be evaporated is place We control the temperature as such that the material will

evaporate and the heat will not cause the filament boat to crack

Because P = Isup2 R (where P is power I is current and R is resistance) to avoid the current to flow

where it is not desired we decided that the material for the Thermocouple shown in figure 4-3 should be

Copper ᴓ 63 mm We choose it that way because Copper has very good heat dissipation characteristics

and the resistance value is low It can reduce the value of the current enough to make the thermocouple to

create heat

Fig 4-3 Thermocouple

To the thermocouple we attach the tungsten filament boat We need to take notice of materials to be

used in this design because when using high current the tungsten filament boar will heat up and so the

material must be able to keep up with the heating potential of tungsten and has a low coefficient of heat

dissipation to avoid the tungsten to fail when heating up and therefore not evaporating Considering all

this we decide to use Stainless Steel

Because this clamp will be assembled inside the chamber after many revisions it was determined it

will have the shape shown in figure 4-4

Fig 4-4 Filament Boat Clamp Design

80

For the tungsten filament boat we bought the product from a distributor The dimensions are

Length 100 mm

Width 10 mm

Height 1 mm

Our thermocouple is 15 in but the pass way C is 4 in so we need to attach a Flange that connects

15in to 4in Because these specifications are quite difficult to achieve by Milling we had to use

electrical wire cutting

For the laser clamping system where the laser that is going to be AR coated will be placed will be

connected to pass way A the assembly is shown in figure 4-5 below

Fig 4-5 Cover Assembly

For this design we used an O-ring instead of a gasket so as to save time The design of the assembly

where the laser will be placed is shown in figure 4-6

Fig 4-6 Upper Cover Inner Assembly

D

E

F

81

Point D is the plate in the assembly where the laser diode will be fixed Because of the easy

processing we decide to use Aluminum and it is screwed to the top cover Point E is the connection for

the Quartz crystal resonator and it is designed in the same as point F in this way the results of the quartz

microbalance system will be more accurate in real time Point F is the final resting place for the laser

diode We use a Thor Labs Base with dimensions of ᴓ 9mm and ᴓ 56mm for two different size laser

diodes It just needs to be plugged in for easy installation

From figure 4-6 we know that the system needs signal system connections and because of the

change in temperature inside the chamber this could affect the functioning of the quartz microbalance so

we also need to install water tubes for cooling This is shown in figure 4-7 below

Fig 4-7 Diagram of Upper Cover Connections

In figure 4-8 we show the Feed through connections and their functions

Fig 4-8 Feed through Diagram

82

1 SQM-160 wire 5 Laser Connection 1 (Vin)

2 SQM-160 (G) 6 Laser Connection 2 (G)

3 K-Type-1 7 Laser Connection 3 (PD)

4 K-Type-2 8 Not In Use

The fully assembled chamber is shown in figure 4-9

Fig 4-9 Fully Assembled Chamber

422 Quartz Crystal Microbalance

For measuring the deposition on our target for coating we used the Inficon SQM-160 RateThickness

Monitor It is an easy to use instrument for measuring many types of thin-film coatings as shown in

figure 4-10

(a) Front Panel (b) Back Panel

Fig 4-10 Inficon SQM-160

83

Table 4-1 shows the technical specifications for this equipment

Number of sensors 2 Standard 4 additional optional

Sensor Frequency Range 40 MHz ~ 60 MHz

Reference Frequency Accuracy 002

Thickness Display Resolution 1 Aring

Thickness Resolution 015 Aring (Std) 0037 Aring (Hi Res)

Density of Stored Films 05-9999 gmcc

Tooling 10-399

Z-Factor 010-1000

Final Thickness 0000-9999k Aring

Measurement Period 15 to 2 sec

Simulation Mode Yes

Frequency Mode Yes

Rate Resolution 011 Arings

Dual Crystal Yes

Etch Mode Yes

Crystal Tooling 10-399

Crystal Fail Min Max 40 to 60 MHz 41 to 61 MHz

Power 100-120 200-240~plusmn10 nominal 20W

Operation Environment 0degC ~ 50degC

0 ~ 80 RH non-condensing

0 ~ 2000 meters

Class 1 Equipment

Pollution Degree 2

Rack Dimensions 885mm x 2127mm x 1969mm

Weight 27 kg

Table 4-1 Inficon SQM-160 RateThickness Monitor Specs

84

To the SQM-160 we need to connect an Oscillator We use the Sigma Instruments Remote Oscillator

Ser No 2 268 as shown in figure 4-11

Fig 4-11 Sigma Instruments Remote Oscillator

The connections diagram is shown in figure 4-12

Fig 4-12 SQM-160 Connections Diagram

85

423 Turbo Pump

For our experiments we used the Pfeiffer TCP 015 Electronic Drive Unit shown below in figure 4-13

Table 4-2 shows the technical specifications for this equipment

(a) Front Panel (b) Back Panel

Fig 4-13 Pfeiffer TCP 015 Electronic Drive

Connection Voltage (100V) 90-112

Mains Frequency 5060 Hz

Start-up Current 22 A

Nominal Frequency 1500 Hz

Rotation Speed 10V = 1500Hz plusmn2

Analog Output Current 10 V = 25 A plusmn 5

Rotation Speed Switchpoint 750 Hz

Works Setting 8 min

Permissible Ambient Temperature 0degC ~ 40degC

Dimensions Front Panel 1285mm x 1063mm

Insertion Length 227mm

Weight 27 Kg

Table 4-2 Pfeiffer TCP 015 Electronic Drive Specs

86

The connections diagram is shown in figure 4-14

Fig 4-14Connections Diagram for Pfeiffer TCP 015

To measure the pressure inside the chamber we use the Granville Phillips 375 Convectron Vacuum

Pressure Controller shown in figure 4-15

(a) Front Panel (b) Back Panel

Fig 4-15 Granville Phillips 375 Convectron

87

Its dimensions are shown in figure 4-16

Fig 4-16 Dimensions of Convectron

Table 4-3 shows the technical specifications for this equipment

Table 4-3 Granville Phillips 375 Convectron Vacuum Pressure Controller Specs

88

424 Multimeter

For our experiment we used the Keithley 2000 Digital Multimeter as shown in figure 4-17

(a) Front Panel (b) Back Panel

Fig 4-17 Keithley Model 2000 6-12-Digit Digital Multimeter

Its technical specifications are shown in table 4-4

Table 4-4 Keithley Model 2000 6-12-Digit Digital Multimeter Specs

89

43 Experiment Procedure

1 Connecting together the equipment and the chamber

(1) We first connect the resonator to the thickness monitor and connect the other side to the

chamber

(2) We now connect the flexible tubes to the turbo pump on one side and to the chamber on the

other

(3) We need to check that tubes are tightly connected to avoid any leaks in the vacuum pumping

process which will not allow us to get to our goal of Torr As shown in figure 4-18

(4) Connect the convectron to the system as shown in figure 4-19

Fig 4-18 checking for leaks using alcohol

Fig 4-19 Convectron attached to System

90

(5) Attach the clamps of the Multimeter to the bottom of the chamber as shown in figure 4-20

(6) Place the Quartz crystal in place

(7) Close tight vacuum chamber

(8) Connect all electrical appliances to power source

Fig 4-20 Multimeter Connections

2 Starting up the System

(1) We turn on all the devices as such Check all systems are ready to function Reset all values

that might be left over from previous tests

(2) Start the thickness monitor and set all values for this experiment In our case we got to testing

the system but not actual coating So we used the simulation mode of the thickness monitor as

shown in figure 4-21

Fig 4-21 Simulation Mode

91

(3) Start the turbo pump Make sure the lid on the vacuum chamber is tightly closed

(4) Start convectron and record initial pressure

(5) Start Multimeter and record initial current

3 Coating Process

(1) If we have the deposition material inside the filament boat the power source for the high

current must be started as well

(2) Record all initial values for thickness current pressure

(3) For an ideal experiment we need a thickness of around 101 nm a pressure of Torr and

a current of 300 A

44 Results

From previous experiments we have shown that we can turn a LED into a laser by means of AR

Coating In figure 4-22 shown below we can compare the actual results of a Diode before and after AR

coating From the blue line we can see that when the diode is at a current of 15mA its light will change

from LED to laser and if we look at the red line its critical current is around 30 to 35 mA

Fig 4-22 AR Coating Comparison for Laser Diodes

This means that the light emitted is not as strong as if the diode had been coated because inside the

chamber there must be some excitation first so the reflectivity of both sides inside the diode must be high

So because of the coating in one of the sides we have opened a door and let the light come out so the

critical current is risen as such and will be higher value than that of before the coating

92

In the following figures we can see the difference between before and after coating in a material The

thickness is around 1016 nm for this material

Fig 4-23 Before Coating

Fig 4-24 After Coating

93

Chapter 5 CONCLUSIONS AND RECOMMENDATIONS

51 Conclusions

For the first part of this independent study taking into consideration the data that came out of our

research and that sent by the provider we can say

1 SUM 23 after heat treatment will unexpectedly develop cracking in the middle of the tensile

testing process and suddenly break

2 Itrsquos possible that in the process of heat treatment to the SUM 23 material the treatment was not

uniform and this will create a pre-loaded moment force on one side that pushes on the other side

of the specimen resulting in material deformation

3 In the process of attaching the strain gauges to the materials it is very easy to make errors due to

poor adhesion or sudden removal in the tensile testing process

For our second part of the independent study the following can be made

1 At the beginning of this independent study we had no idea what Bose-Einstein Condensate was

or what was its purpose After much literature we finally comprehended the basic principles to

put into practice for our research

2 Our systemrsquos basic working principles and equipmentrsquos complexity are a little difficult to grasp

but hopefully we were able to understand enough of it

3 Theoretically from relation between the power and current we can know the advantages and

disadvantages of AR Coating

4 We were able to assemble the system and run test on its functions Even though we were able to

do this there is still much more work left to do with this system

52 Recommendations

For the Tensile Testing the following can be said

1 Ask the provider to check on the process of heat treatment on the SUM 23 material and give

them the information we have gathered through our test so they can correct for the mechanical

properties found if any change is needed

2 To avoid the problem of the inaccuracy of the poor adhesion of strain gauges we can attach

multiple strain gauges to the same one specimen so as to correlate data and improve our results

For the AR Coating the following can be said

1 We need to make sure that there are no physical defects on the main body of the chamber so as to

achieve maximum efficiency in the vacuum process If there was then the vacuum will arrive to

certain point and then start to decrease

2 It would be preferable to add some sort of visual aid that will allow the user to check the inside of

the chamber without actually opening it This will help us determine at what times we should

manipulate the current to better evaporate the substrate

94

REFERENCES

[1] A L Window Strain Gauge Technology Elsevier Applied Science London and New York 2nd

Edition 1992

[2] CC Perry and HR Lissner Strain Gauge Primer McGraw-Hill Book Co Inc New York 1955

[3] James W Dally William F Riley McGraw-Hill 1978

[4] University of Colorado Boulder BEC - What is it and where did the idea come from

httpwwwcoloradoeduphysics2000becwhat_is_ithtml

[5] Ultraslow Light amp Bose-Einstein Condensates Two-way Control with Coherent Light amp Atom

Fields Harvard Hau Lab Dr Lene Vestergaard Hau Optics amp Photonics News 16 1995

[6] The Art of Taming Light Ultra-slow and Stopped Light Harvard Hau Lab Dr Lene

Vestergaard Hau Europhysics News 2004

[7] Nonlinear Optics Shocking Superfluids Harvard Hau Lab Dr Lene Vestergaard Hau Nature

Physics 2007

[8] Model P3 Strain Indicator and Recorder Instruction Manual Vishay Micro-Measurements 2005

[9] Granville-Phillips Series 375 Convectron Vacuum Gauge Controller Instruction Manual Brooks

Automation 2008

[10] Effect of Film Thickness on the Validity of the Sauerbrey Equation for Hydrated Polyelectrolyte

Films Vogt Lin Wu White 2004

[11] Quartz Crystal Microbalance Study of DNA Immobilization and Hybridization for DNA Sensor

Development Chang Zhao 2008

[12] Installation of Strain Gages with SR-4 PrecoatAdhesive Vishay Micro-Measurements 2005

[13] Strain Gauge Measurement ndash A Tutorial National Instruments 1998

[14] Correlation between Vickers Hardness Number and Yield Stress of Cold-Formed Products

Yavuz Tekkaya

[15] httpsenwikipediaorg

Page 51: PC Hinge Materials Testing and AR Laser Diode Coating

51

(8) We need to make sure that the gauge and the specimen will be firmly attached so we gently

apply pressure with our thumb

(h)

(9) After the adhesive is fully dry we can carefully rip off the tape

(i)

(10) We need to do the whole process twice one for the horizontally placed strain gauge and one

for the vertically placed strain gauge

52

(j)

(11) We now proceed to solder the wires to the strain gauge

(k)

(12) After soldering we use a Volt Multimeter to measure that there is no contact between wires

If there is none then the specimen is ready for testing

(l)

(13) We now need to measure a 5cm distance and mark it to check and compare the elongation

before and after the tensile testing

(m)

53

Fig 3-9 Specimen-Strain Gauge Process

3 Tensile Test

(1) Enter the computer application that controls the tensile testing machine

(2) Turn on the tensile testing machine main switch

(3) Adjust the hydraulic pump to go back to its original position

(4) Bring the lowering motor down to a distance enough so as to attach the tensile specimen to the

system open the clamps and secure the specimen

(a)

(5) Connect all the necessary wires to the strain indicator equipment

54

(b)

(6) Start the ascending motor and wait for the expansion

(c)

Fig 3-10 Specimen-Tensile Testing Process

4 Start the Test

(1) Enter the software application and enter some variables needed for the experiment in the

specific screen

(2) Go back to the main screen and press the [測試] (measure) button to start the test and auto

recording in the software

(3) After the specimen breaks the mechanical device will automatically stop and ask the user to

enter the total displacement We take out the specimen from the testing machine and adjust the

machinersquos position back to its original position

(4) Save the results information

(5) Record the results from the strain indicator

34 Results

From this experiment we can get the Poissonrsquos Ratio Youngrsquos Modulus and Yield Strength etc and

because of the slippage phenomenon in the clamp at the moment of the test then the Elastic Limit will

display some yield phenomena So omit any undesirable results we just take the Yield portion of the

results as reference

In the process of the experiment the most important part to attend to is the attaching of the strain

gauge because the gaugersquos purpose is to measure the strain developed during the test and this strain

might be very small If the gaugersquos angle change during the test ie is not well attached this will affect

the accuracy of the measurements of Poissonrsquos ratio and Youngrsquos modulus

55

The materials provided by the manufacturer are SUM 23 and SUM 43 steel round bars and these two

types of materials have been through different heat treatment processes so they can be sub-divided

further into untreated material heat-treated material and black surface heat treated material for the two

materials with heat treatment the treatment process and finished are different In the end we only have

the mechanical properties that were calculated after our research of these materials

All of the specifications are identical to those shown in figure 3-6

341 SUM 23

Fig 3-11 SUM 23 Untreated Material

Number 7 10

Hardness(HRB) 74 75

Yield Stress (MPa) 448 440

Tensile Strength (MPa) 544 560

Poissonrsquos Ratio 029 027

Youngrsquos Modulus (GPa) 203 210

Cut-off Area Shrinking () 42 41

Elongation () 1125 1011

Table 3-5 Mechanical Properties of SUM 23 Untreated

56

Stress-Strain Diagram

(a)

(b)

57

Fig 3-12 Stress-Strain Diagrams for (a) 7 Round Bar and (b) 10 Round Bar

Cut-Off Area

(a)

(b)

Fig 3-13 Cut-Off Area of (a) 7 Round Bar and (b) 10 Round Bar

58

SUM 23 Nickel Round Bar

Fig 3-14 SUM 23 Nickel Material

Number 1 2 3 4

Hardness(HRB) 48 50 49 48

Yield Stress (MPa) 370 370 380 400

Tensile Strength (MPa) 455 451 450 450

Poissonrsquos Ratio 028 046 029 026

Youngrsquos Modulus (GPa) 243 303 246 206

Cut-off Area Shrinking () 803 803 726 601

Elongation () 566 65 602 647

Table 3-6 Mechanical Properties of SUM 23 Nickel

59

Stress-Strain Diagram

(a)

60

(b)

(c)

(d)

61

Fig 3-15 Stress-Strain Diagrams for (a) 1 Round Bar (b) 2 Round Bar (c) 3 Round Bar and (d)

4 Round Bar

Cut-Off Area

(a)

(b)

62

(c)

(d)

Fig 3-16 Cut-Off Area of (a) 1 Round Bar (b) 2 Round Bar (c) 3 Round Bar and (d) 4 Round

Bar

63

SUM 23 Black Surface Round Bar

Fig 3-17 SUM 23 Black Surface Material

Number 1 2 3

Hardness(HRB) 51 50 51

Yield Stress (MPa) 378 371 369

Tensile Strength (MPa) 467 465 464

Poissonrsquos Ratio 03 016 04

Youngrsquos Modulus (GPa) 215 266 266

Cut-off Area Shrinking () 986 94 848

Elongation () 748 805 761

Table 3-7 Mechanical Properties of SUM 23 Black Surface Material

64

Stress-Strain Diagram

(a)

(b)

65

(c)

Fig 3-18 Stress-Strain Diagrams for (a) 1 Round Bar 2 Round Bar and (c) 3 Round Bar

Cut-Off Surface

(a)

66

(b)

(c)

Fig 3-19 Cut-Off Surface of (a) 1 Round Bar 2 Round Bar and (c) 3 Round Bar

67

342 SUM 43

Fig 3-20 Untreated SUM 43 Untreated Material

Number 1 5

Hardness(HRB) 76 75

Yield Stress (MPa) 572 594

Tensile Strength (MPa) 743 785

Poissonrsquos Ratio 027 029

Youngrsquos Modulus (GPa) 200 202

Cut-off Area Shrinking () 338 2944

Elongation () 857 894

Table 3-8 Mechanical Properties of SUM 43 Untreated

68

Stress-Strain Diagrams

(a)

(b)

Fig 3-21 Stress-Strain Diagrams for SUM 43 (a) 1 Round Bar and (b) 5 Round Bar

69

Cut-Off Area

(a)

(b)

Fig 3-22 Cut-Off Area of SUM 43 (a) 1 Round Bar and (b) 5 Round Bar

70

SUM 43 Nickel Round Bar

Fig 3-23 SUM 43 Nickel Material

Number 4 5

Hardness(HRB) 51 50

Yield Stress (MPa) 1580 1544

Tensile Strength (MPa) 1639 1625

Poissonrsquos Ratio 03 028

Youngrsquos Modulus (GPa) 194 201

Cut-off Area Shrinking () 1697 137

Elongation () 376 265

Table 3-9 Mechanical Properties of SUM 43 Nickel

71

Stress-Strain Diagrams

(a)

(b)

Fig 3-24 Stress-Strain Diagrams for (a) 4 Round Bar and (b) 5 Round Bar

72

Cut-Off Area

(a)

(b)

Fig 3-25 Cut-Off Area of (a) 4 Round Bar and (b) 5 Round Bar

73

SUM 43 Black Surface Material

Fig 3-26 SUM 43 Black Surface Material

Number 3 5

Hardness(HRB) 56 56

Yield Stress (MPa) 1416 1361

Tensile Strength (MPa) 1591 1402

Poissonrsquos Ratio 029 031

Youngrsquos Modulus (GPa) 200 202

Cut-off Area Shrinking () 139 124

Elongation () 24 24

Table 3-10 Mechanical Properties of SUM 43 Black Surface Material

74

Stress-Strain Diagrams

0 2 4 6 8 10 12 14

-200

0

200

400

600

800

1000

1200

1400

1600

1800

應力 (MPa)

應變()

(a)

0 2 4 6 8 10

-200

0

200

400

600

800

1000

1200

1400

1600

應力

(MPa)

位移 ()

(b)

Fig 3-27 Stress-Strain Diagrams for (a) 3 Round Bar and (b) 5 Round Bar

(Note These curves were formulated using Visual Solutions Inc VisSim Software)

75

Cut-Off Area

(a)

(b)

Fig 3-28 Cut-Off Area of (a) 3 Round Bar and (b) 5 Round Bar

76

The force value (N) was retrieved from the Universal Testing Machine

The Poissonrsquos Ratio (ε) is calculated as

ε =

the values for the Poissonrsquos Ratio are in average around 0297

The Youngrsquos Modulus (E) is calculated as

E =

Where

Stress =

Cross-sectional Area =

where D is the Diameter

The value for D was in average around 1258 mm

The values shown by the computer because there is Slippage phenomena between the Clamp and the

specimen will not be taken into consideration for the elongation strain and Youngrsquos modulus and we will

refer to the values that we have meticulously calculated

77

Chapter 4 AR COATING IN DEPTH

41 Experimentrsquos Purpose and Principles

By means of a vacuum chamber and several other instruments we intend to apply Anti-Reflective

Coating using deposition process to a laser diode and in this way reduce its refraction so as to make it

lose less light in the process of amplification and we can control certain wavelengths we want produced

for certain desired applications in our case we are attempting to re-create a Bose-Einstein Condensate

An optimal BEC apparatus is shown in figure 4-1

Fig 4-1 BEC Apparatus

The main point of this experiment is to build a vacuum chamber system attach all the instrumentation

needed (Vacuum pump deposition meter and voltmeter) and use it to apply AR coating to a laser diode

After we have accomplished the AR coating other team will be in charge of designing the BEC apparatus

and use the results of our research

78

42 Experimentrsquos Equipment

421 Vacuum Chamber

For this research we designed a vacuum chamber whose main body is shown in figure 4-2 Its

dimensions are

Width 240 mm

Length 240 mm

Height 200 mm

Outer Diameter 4 in

Inner Diameter 15 in

Fig 4-2 Vacuum Chamber Main Body

The chamber is made up of 6 pass ways pass way A is the connection with the Laser Deposition

Equipment pass way B is the connection with the Turbo Pump and pass way C is for the connection with

the Deposition Source

A

C

B

79

Pass way C is for the deposition source as mentioned above This is a system where a thermal

resistance is heated by passing a high current through it which heats up a filament boat (made of tungsten)

where the material to be evaporated is place We control the temperature as such that the material will

evaporate and the heat will not cause the filament boat to crack

Because P = Isup2 R (where P is power I is current and R is resistance) to avoid the current to flow

where it is not desired we decided that the material for the Thermocouple shown in figure 4-3 should be

Copper ᴓ 63 mm We choose it that way because Copper has very good heat dissipation characteristics

and the resistance value is low It can reduce the value of the current enough to make the thermocouple to

create heat

Fig 4-3 Thermocouple

To the thermocouple we attach the tungsten filament boat We need to take notice of materials to be

used in this design because when using high current the tungsten filament boar will heat up and so the

material must be able to keep up with the heating potential of tungsten and has a low coefficient of heat

dissipation to avoid the tungsten to fail when heating up and therefore not evaporating Considering all

this we decide to use Stainless Steel

Because this clamp will be assembled inside the chamber after many revisions it was determined it

will have the shape shown in figure 4-4

Fig 4-4 Filament Boat Clamp Design

80

For the tungsten filament boat we bought the product from a distributor The dimensions are

Length 100 mm

Width 10 mm

Height 1 mm

Our thermocouple is 15 in but the pass way C is 4 in so we need to attach a Flange that connects

15in to 4in Because these specifications are quite difficult to achieve by Milling we had to use

electrical wire cutting

For the laser clamping system where the laser that is going to be AR coated will be placed will be

connected to pass way A the assembly is shown in figure 4-5 below

Fig 4-5 Cover Assembly

For this design we used an O-ring instead of a gasket so as to save time The design of the assembly

where the laser will be placed is shown in figure 4-6

Fig 4-6 Upper Cover Inner Assembly

D

E

F

81

Point D is the plate in the assembly where the laser diode will be fixed Because of the easy

processing we decide to use Aluminum and it is screwed to the top cover Point E is the connection for

the Quartz crystal resonator and it is designed in the same as point F in this way the results of the quartz

microbalance system will be more accurate in real time Point F is the final resting place for the laser

diode We use a Thor Labs Base with dimensions of ᴓ 9mm and ᴓ 56mm for two different size laser

diodes It just needs to be plugged in for easy installation

From figure 4-6 we know that the system needs signal system connections and because of the

change in temperature inside the chamber this could affect the functioning of the quartz microbalance so

we also need to install water tubes for cooling This is shown in figure 4-7 below

Fig 4-7 Diagram of Upper Cover Connections

In figure 4-8 we show the Feed through connections and their functions

Fig 4-8 Feed through Diagram

82

1 SQM-160 wire 5 Laser Connection 1 (Vin)

2 SQM-160 (G) 6 Laser Connection 2 (G)

3 K-Type-1 7 Laser Connection 3 (PD)

4 K-Type-2 8 Not In Use

The fully assembled chamber is shown in figure 4-9

Fig 4-9 Fully Assembled Chamber

422 Quartz Crystal Microbalance

For measuring the deposition on our target for coating we used the Inficon SQM-160 RateThickness

Monitor It is an easy to use instrument for measuring many types of thin-film coatings as shown in

figure 4-10

(a) Front Panel (b) Back Panel

Fig 4-10 Inficon SQM-160

83

Table 4-1 shows the technical specifications for this equipment

Number of sensors 2 Standard 4 additional optional

Sensor Frequency Range 40 MHz ~ 60 MHz

Reference Frequency Accuracy 002

Thickness Display Resolution 1 Aring

Thickness Resolution 015 Aring (Std) 0037 Aring (Hi Res)

Density of Stored Films 05-9999 gmcc

Tooling 10-399

Z-Factor 010-1000

Final Thickness 0000-9999k Aring

Measurement Period 15 to 2 sec

Simulation Mode Yes

Frequency Mode Yes

Rate Resolution 011 Arings

Dual Crystal Yes

Etch Mode Yes

Crystal Tooling 10-399

Crystal Fail Min Max 40 to 60 MHz 41 to 61 MHz

Power 100-120 200-240~plusmn10 nominal 20W

Operation Environment 0degC ~ 50degC

0 ~ 80 RH non-condensing

0 ~ 2000 meters

Class 1 Equipment

Pollution Degree 2

Rack Dimensions 885mm x 2127mm x 1969mm

Weight 27 kg

Table 4-1 Inficon SQM-160 RateThickness Monitor Specs

84

To the SQM-160 we need to connect an Oscillator We use the Sigma Instruments Remote Oscillator

Ser No 2 268 as shown in figure 4-11

Fig 4-11 Sigma Instruments Remote Oscillator

The connections diagram is shown in figure 4-12

Fig 4-12 SQM-160 Connections Diagram

85

423 Turbo Pump

For our experiments we used the Pfeiffer TCP 015 Electronic Drive Unit shown below in figure 4-13

Table 4-2 shows the technical specifications for this equipment

(a) Front Panel (b) Back Panel

Fig 4-13 Pfeiffer TCP 015 Electronic Drive

Connection Voltage (100V) 90-112

Mains Frequency 5060 Hz

Start-up Current 22 A

Nominal Frequency 1500 Hz

Rotation Speed 10V = 1500Hz plusmn2

Analog Output Current 10 V = 25 A plusmn 5

Rotation Speed Switchpoint 750 Hz

Works Setting 8 min

Permissible Ambient Temperature 0degC ~ 40degC

Dimensions Front Panel 1285mm x 1063mm

Insertion Length 227mm

Weight 27 Kg

Table 4-2 Pfeiffer TCP 015 Electronic Drive Specs

86

The connections diagram is shown in figure 4-14

Fig 4-14Connections Diagram for Pfeiffer TCP 015

To measure the pressure inside the chamber we use the Granville Phillips 375 Convectron Vacuum

Pressure Controller shown in figure 4-15

(a) Front Panel (b) Back Panel

Fig 4-15 Granville Phillips 375 Convectron

87

Its dimensions are shown in figure 4-16

Fig 4-16 Dimensions of Convectron

Table 4-3 shows the technical specifications for this equipment

Table 4-3 Granville Phillips 375 Convectron Vacuum Pressure Controller Specs

88

424 Multimeter

For our experiment we used the Keithley 2000 Digital Multimeter as shown in figure 4-17

(a) Front Panel (b) Back Panel

Fig 4-17 Keithley Model 2000 6-12-Digit Digital Multimeter

Its technical specifications are shown in table 4-4

Table 4-4 Keithley Model 2000 6-12-Digit Digital Multimeter Specs

89

43 Experiment Procedure

1 Connecting together the equipment and the chamber

(1) We first connect the resonator to the thickness monitor and connect the other side to the

chamber

(2) We now connect the flexible tubes to the turbo pump on one side and to the chamber on the

other

(3) We need to check that tubes are tightly connected to avoid any leaks in the vacuum pumping

process which will not allow us to get to our goal of Torr As shown in figure 4-18

(4) Connect the convectron to the system as shown in figure 4-19

Fig 4-18 checking for leaks using alcohol

Fig 4-19 Convectron attached to System

90

(5) Attach the clamps of the Multimeter to the bottom of the chamber as shown in figure 4-20

(6) Place the Quartz crystal in place

(7) Close tight vacuum chamber

(8) Connect all electrical appliances to power source

Fig 4-20 Multimeter Connections

2 Starting up the System

(1) We turn on all the devices as such Check all systems are ready to function Reset all values

that might be left over from previous tests

(2) Start the thickness monitor and set all values for this experiment In our case we got to testing

the system but not actual coating So we used the simulation mode of the thickness monitor as

shown in figure 4-21

Fig 4-21 Simulation Mode

91

(3) Start the turbo pump Make sure the lid on the vacuum chamber is tightly closed

(4) Start convectron and record initial pressure

(5) Start Multimeter and record initial current

3 Coating Process

(1) If we have the deposition material inside the filament boat the power source for the high

current must be started as well

(2) Record all initial values for thickness current pressure

(3) For an ideal experiment we need a thickness of around 101 nm a pressure of Torr and

a current of 300 A

44 Results

From previous experiments we have shown that we can turn a LED into a laser by means of AR

Coating In figure 4-22 shown below we can compare the actual results of a Diode before and after AR

coating From the blue line we can see that when the diode is at a current of 15mA its light will change

from LED to laser and if we look at the red line its critical current is around 30 to 35 mA

Fig 4-22 AR Coating Comparison for Laser Diodes

This means that the light emitted is not as strong as if the diode had been coated because inside the

chamber there must be some excitation first so the reflectivity of both sides inside the diode must be high

So because of the coating in one of the sides we have opened a door and let the light come out so the

critical current is risen as such and will be higher value than that of before the coating

92

In the following figures we can see the difference between before and after coating in a material The

thickness is around 1016 nm for this material

Fig 4-23 Before Coating

Fig 4-24 After Coating

93

Chapter 5 CONCLUSIONS AND RECOMMENDATIONS

51 Conclusions

For the first part of this independent study taking into consideration the data that came out of our

research and that sent by the provider we can say

1 SUM 23 after heat treatment will unexpectedly develop cracking in the middle of the tensile

testing process and suddenly break

2 Itrsquos possible that in the process of heat treatment to the SUM 23 material the treatment was not

uniform and this will create a pre-loaded moment force on one side that pushes on the other side

of the specimen resulting in material deformation

3 In the process of attaching the strain gauges to the materials it is very easy to make errors due to

poor adhesion or sudden removal in the tensile testing process

For our second part of the independent study the following can be made

1 At the beginning of this independent study we had no idea what Bose-Einstein Condensate was

or what was its purpose After much literature we finally comprehended the basic principles to

put into practice for our research

2 Our systemrsquos basic working principles and equipmentrsquos complexity are a little difficult to grasp

but hopefully we were able to understand enough of it

3 Theoretically from relation between the power and current we can know the advantages and

disadvantages of AR Coating

4 We were able to assemble the system and run test on its functions Even though we were able to

do this there is still much more work left to do with this system

52 Recommendations

For the Tensile Testing the following can be said

1 Ask the provider to check on the process of heat treatment on the SUM 23 material and give

them the information we have gathered through our test so they can correct for the mechanical

properties found if any change is needed

2 To avoid the problem of the inaccuracy of the poor adhesion of strain gauges we can attach

multiple strain gauges to the same one specimen so as to correlate data and improve our results

For the AR Coating the following can be said

1 We need to make sure that there are no physical defects on the main body of the chamber so as to

achieve maximum efficiency in the vacuum process If there was then the vacuum will arrive to

certain point and then start to decrease

2 It would be preferable to add some sort of visual aid that will allow the user to check the inside of

the chamber without actually opening it This will help us determine at what times we should

manipulate the current to better evaporate the substrate

94

REFERENCES

[1] A L Window Strain Gauge Technology Elsevier Applied Science London and New York 2nd

Edition 1992

[2] CC Perry and HR Lissner Strain Gauge Primer McGraw-Hill Book Co Inc New York 1955

[3] James W Dally William F Riley McGraw-Hill 1978

[4] University of Colorado Boulder BEC - What is it and where did the idea come from

httpwwwcoloradoeduphysics2000becwhat_is_ithtml

[5] Ultraslow Light amp Bose-Einstein Condensates Two-way Control with Coherent Light amp Atom

Fields Harvard Hau Lab Dr Lene Vestergaard Hau Optics amp Photonics News 16 1995

[6] The Art of Taming Light Ultra-slow and Stopped Light Harvard Hau Lab Dr Lene

Vestergaard Hau Europhysics News 2004

[7] Nonlinear Optics Shocking Superfluids Harvard Hau Lab Dr Lene Vestergaard Hau Nature

Physics 2007

[8] Model P3 Strain Indicator and Recorder Instruction Manual Vishay Micro-Measurements 2005

[9] Granville-Phillips Series 375 Convectron Vacuum Gauge Controller Instruction Manual Brooks

Automation 2008

[10] Effect of Film Thickness on the Validity of the Sauerbrey Equation for Hydrated Polyelectrolyte

Films Vogt Lin Wu White 2004

[11] Quartz Crystal Microbalance Study of DNA Immobilization and Hybridization for DNA Sensor

Development Chang Zhao 2008

[12] Installation of Strain Gages with SR-4 PrecoatAdhesive Vishay Micro-Measurements 2005

[13] Strain Gauge Measurement ndash A Tutorial National Instruments 1998

[14] Correlation between Vickers Hardness Number and Yield Stress of Cold-Formed Products

Yavuz Tekkaya

[15] httpsenwikipediaorg

Page 52: PC Hinge Materials Testing and AR Laser Diode Coating

52

(j)

(11) We now proceed to solder the wires to the strain gauge

(k)

(12) After soldering we use a Volt Multimeter to measure that there is no contact between wires

If there is none then the specimen is ready for testing

(l)

(13) We now need to measure a 5cm distance and mark it to check and compare the elongation

before and after the tensile testing

(m)

53

Fig 3-9 Specimen-Strain Gauge Process

3 Tensile Test

(1) Enter the computer application that controls the tensile testing machine

(2) Turn on the tensile testing machine main switch

(3) Adjust the hydraulic pump to go back to its original position

(4) Bring the lowering motor down to a distance enough so as to attach the tensile specimen to the

system open the clamps and secure the specimen

(a)

(5) Connect all the necessary wires to the strain indicator equipment

54

(b)

(6) Start the ascending motor and wait for the expansion

(c)

Fig 3-10 Specimen-Tensile Testing Process

4 Start the Test

(1) Enter the software application and enter some variables needed for the experiment in the

specific screen

(2) Go back to the main screen and press the [測試] (measure) button to start the test and auto

recording in the software

(3) After the specimen breaks the mechanical device will automatically stop and ask the user to

enter the total displacement We take out the specimen from the testing machine and adjust the

machinersquos position back to its original position

(4) Save the results information

(5) Record the results from the strain indicator

34 Results

From this experiment we can get the Poissonrsquos Ratio Youngrsquos Modulus and Yield Strength etc and

because of the slippage phenomenon in the clamp at the moment of the test then the Elastic Limit will

display some yield phenomena So omit any undesirable results we just take the Yield portion of the

results as reference

In the process of the experiment the most important part to attend to is the attaching of the strain

gauge because the gaugersquos purpose is to measure the strain developed during the test and this strain

might be very small If the gaugersquos angle change during the test ie is not well attached this will affect

the accuracy of the measurements of Poissonrsquos ratio and Youngrsquos modulus

55

The materials provided by the manufacturer are SUM 23 and SUM 43 steel round bars and these two

types of materials have been through different heat treatment processes so they can be sub-divided

further into untreated material heat-treated material and black surface heat treated material for the two

materials with heat treatment the treatment process and finished are different In the end we only have

the mechanical properties that were calculated after our research of these materials

All of the specifications are identical to those shown in figure 3-6

341 SUM 23

Fig 3-11 SUM 23 Untreated Material

Number 7 10

Hardness(HRB) 74 75

Yield Stress (MPa) 448 440

Tensile Strength (MPa) 544 560

Poissonrsquos Ratio 029 027

Youngrsquos Modulus (GPa) 203 210

Cut-off Area Shrinking () 42 41

Elongation () 1125 1011

Table 3-5 Mechanical Properties of SUM 23 Untreated

56

Stress-Strain Diagram

(a)

(b)

57

Fig 3-12 Stress-Strain Diagrams for (a) 7 Round Bar and (b) 10 Round Bar

Cut-Off Area

(a)

(b)

Fig 3-13 Cut-Off Area of (a) 7 Round Bar and (b) 10 Round Bar

58

SUM 23 Nickel Round Bar

Fig 3-14 SUM 23 Nickel Material

Number 1 2 3 4

Hardness(HRB) 48 50 49 48

Yield Stress (MPa) 370 370 380 400

Tensile Strength (MPa) 455 451 450 450

Poissonrsquos Ratio 028 046 029 026

Youngrsquos Modulus (GPa) 243 303 246 206

Cut-off Area Shrinking () 803 803 726 601

Elongation () 566 65 602 647

Table 3-6 Mechanical Properties of SUM 23 Nickel

59

Stress-Strain Diagram

(a)

60

(b)

(c)

(d)

61

Fig 3-15 Stress-Strain Diagrams for (a) 1 Round Bar (b) 2 Round Bar (c) 3 Round Bar and (d)

4 Round Bar

Cut-Off Area

(a)

(b)

62

(c)

(d)

Fig 3-16 Cut-Off Area of (a) 1 Round Bar (b) 2 Round Bar (c) 3 Round Bar and (d) 4 Round

Bar

63

SUM 23 Black Surface Round Bar

Fig 3-17 SUM 23 Black Surface Material

Number 1 2 3

Hardness(HRB) 51 50 51

Yield Stress (MPa) 378 371 369

Tensile Strength (MPa) 467 465 464

Poissonrsquos Ratio 03 016 04

Youngrsquos Modulus (GPa) 215 266 266

Cut-off Area Shrinking () 986 94 848

Elongation () 748 805 761

Table 3-7 Mechanical Properties of SUM 23 Black Surface Material

64

Stress-Strain Diagram

(a)

(b)

65

(c)

Fig 3-18 Stress-Strain Diagrams for (a) 1 Round Bar 2 Round Bar and (c) 3 Round Bar

Cut-Off Surface

(a)

66

(b)

(c)

Fig 3-19 Cut-Off Surface of (a) 1 Round Bar 2 Round Bar and (c) 3 Round Bar

67

342 SUM 43

Fig 3-20 Untreated SUM 43 Untreated Material

Number 1 5

Hardness(HRB) 76 75

Yield Stress (MPa) 572 594

Tensile Strength (MPa) 743 785

Poissonrsquos Ratio 027 029

Youngrsquos Modulus (GPa) 200 202

Cut-off Area Shrinking () 338 2944

Elongation () 857 894

Table 3-8 Mechanical Properties of SUM 43 Untreated

68

Stress-Strain Diagrams

(a)

(b)

Fig 3-21 Stress-Strain Diagrams for SUM 43 (a) 1 Round Bar and (b) 5 Round Bar

69

Cut-Off Area

(a)

(b)

Fig 3-22 Cut-Off Area of SUM 43 (a) 1 Round Bar and (b) 5 Round Bar

70

SUM 43 Nickel Round Bar

Fig 3-23 SUM 43 Nickel Material

Number 4 5

Hardness(HRB) 51 50

Yield Stress (MPa) 1580 1544

Tensile Strength (MPa) 1639 1625

Poissonrsquos Ratio 03 028

Youngrsquos Modulus (GPa) 194 201

Cut-off Area Shrinking () 1697 137

Elongation () 376 265

Table 3-9 Mechanical Properties of SUM 43 Nickel

71

Stress-Strain Diagrams

(a)

(b)

Fig 3-24 Stress-Strain Diagrams for (a) 4 Round Bar and (b) 5 Round Bar

72

Cut-Off Area

(a)

(b)

Fig 3-25 Cut-Off Area of (a) 4 Round Bar and (b) 5 Round Bar

73

SUM 43 Black Surface Material

Fig 3-26 SUM 43 Black Surface Material

Number 3 5

Hardness(HRB) 56 56

Yield Stress (MPa) 1416 1361

Tensile Strength (MPa) 1591 1402

Poissonrsquos Ratio 029 031

Youngrsquos Modulus (GPa) 200 202

Cut-off Area Shrinking () 139 124

Elongation () 24 24

Table 3-10 Mechanical Properties of SUM 43 Black Surface Material

74

Stress-Strain Diagrams

0 2 4 6 8 10 12 14

-200

0

200

400

600

800

1000

1200

1400

1600

1800

應力 (MPa)

應變()

(a)

0 2 4 6 8 10

-200

0

200

400

600

800

1000

1200

1400

1600

應力

(MPa)

位移 ()

(b)

Fig 3-27 Stress-Strain Diagrams for (a) 3 Round Bar and (b) 5 Round Bar

(Note These curves were formulated using Visual Solutions Inc VisSim Software)

75

Cut-Off Area

(a)

(b)

Fig 3-28 Cut-Off Area of (a) 3 Round Bar and (b) 5 Round Bar

76

The force value (N) was retrieved from the Universal Testing Machine

The Poissonrsquos Ratio (ε) is calculated as

ε =

the values for the Poissonrsquos Ratio are in average around 0297

The Youngrsquos Modulus (E) is calculated as

E =

Where

Stress =

Cross-sectional Area =

where D is the Diameter

The value for D was in average around 1258 mm

The values shown by the computer because there is Slippage phenomena between the Clamp and the

specimen will not be taken into consideration for the elongation strain and Youngrsquos modulus and we will

refer to the values that we have meticulously calculated

77

Chapter 4 AR COATING IN DEPTH

41 Experimentrsquos Purpose and Principles

By means of a vacuum chamber and several other instruments we intend to apply Anti-Reflective

Coating using deposition process to a laser diode and in this way reduce its refraction so as to make it

lose less light in the process of amplification and we can control certain wavelengths we want produced

for certain desired applications in our case we are attempting to re-create a Bose-Einstein Condensate

An optimal BEC apparatus is shown in figure 4-1

Fig 4-1 BEC Apparatus

The main point of this experiment is to build a vacuum chamber system attach all the instrumentation

needed (Vacuum pump deposition meter and voltmeter) and use it to apply AR coating to a laser diode

After we have accomplished the AR coating other team will be in charge of designing the BEC apparatus

and use the results of our research

78

42 Experimentrsquos Equipment

421 Vacuum Chamber

For this research we designed a vacuum chamber whose main body is shown in figure 4-2 Its

dimensions are

Width 240 mm

Length 240 mm

Height 200 mm

Outer Diameter 4 in

Inner Diameter 15 in

Fig 4-2 Vacuum Chamber Main Body

The chamber is made up of 6 pass ways pass way A is the connection with the Laser Deposition

Equipment pass way B is the connection with the Turbo Pump and pass way C is for the connection with

the Deposition Source

A

C

B

79

Pass way C is for the deposition source as mentioned above This is a system where a thermal

resistance is heated by passing a high current through it which heats up a filament boat (made of tungsten)

where the material to be evaporated is place We control the temperature as such that the material will

evaporate and the heat will not cause the filament boat to crack

Because P = Isup2 R (where P is power I is current and R is resistance) to avoid the current to flow

where it is not desired we decided that the material for the Thermocouple shown in figure 4-3 should be

Copper ᴓ 63 mm We choose it that way because Copper has very good heat dissipation characteristics

and the resistance value is low It can reduce the value of the current enough to make the thermocouple to

create heat

Fig 4-3 Thermocouple

To the thermocouple we attach the tungsten filament boat We need to take notice of materials to be

used in this design because when using high current the tungsten filament boar will heat up and so the

material must be able to keep up with the heating potential of tungsten and has a low coefficient of heat

dissipation to avoid the tungsten to fail when heating up and therefore not evaporating Considering all

this we decide to use Stainless Steel

Because this clamp will be assembled inside the chamber after many revisions it was determined it

will have the shape shown in figure 4-4

Fig 4-4 Filament Boat Clamp Design

80

For the tungsten filament boat we bought the product from a distributor The dimensions are

Length 100 mm

Width 10 mm

Height 1 mm

Our thermocouple is 15 in but the pass way C is 4 in so we need to attach a Flange that connects

15in to 4in Because these specifications are quite difficult to achieve by Milling we had to use

electrical wire cutting

For the laser clamping system where the laser that is going to be AR coated will be placed will be

connected to pass way A the assembly is shown in figure 4-5 below

Fig 4-5 Cover Assembly

For this design we used an O-ring instead of a gasket so as to save time The design of the assembly

where the laser will be placed is shown in figure 4-6

Fig 4-6 Upper Cover Inner Assembly

D

E

F

81

Point D is the plate in the assembly where the laser diode will be fixed Because of the easy

processing we decide to use Aluminum and it is screwed to the top cover Point E is the connection for

the Quartz crystal resonator and it is designed in the same as point F in this way the results of the quartz

microbalance system will be more accurate in real time Point F is the final resting place for the laser

diode We use a Thor Labs Base with dimensions of ᴓ 9mm and ᴓ 56mm for two different size laser

diodes It just needs to be plugged in for easy installation

From figure 4-6 we know that the system needs signal system connections and because of the

change in temperature inside the chamber this could affect the functioning of the quartz microbalance so

we also need to install water tubes for cooling This is shown in figure 4-7 below

Fig 4-7 Diagram of Upper Cover Connections

In figure 4-8 we show the Feed through connections and their functions

Fig 4-8 Feed through Diagram

82

1 SQM-160 wire 5 Laser Connection 1 (Vin)

2 SQM-160 (G) 6 Laser Connection 2 (G)

3 K-Type-1 7 Laser Connection 3 (PD)

4 K-Type-2 8 Not In Use

The fully assembled chamber is shown in figure 4-9

Fig 4-9 Fully Assembled Chamber

422 Quartz Crystal Microbalance

For measuring the deposition on our target for coating we used the Inficon SQM-160 RateThickness

Monitor It is an easy to use instrument for measuring many types of thin-film coatings as shown in

figure 4-10

(a) Front Panel (b) Back Panel

Fig 4-10 Inficon SQM-160

83

Table 4-1 shows the technical specifications for this equipment

Number of sensors 2 Standard 4 additional optional

Sensor Frequency Range 40 MHz ~ 60 MHz

Reference Frequency Accuracy 002

Thickness Display Resolution 1 Aring

Thickness Resolution 015 Aring (Std) 0037 Aring (Hi Res)

Density of Stored Films 05-9999 gmcc

Tooling 10-399

Z-Factor 010-1000

Final Thickness 0000-9999k Aring

Measurement Period 15 to 2 sec

Simulation Mode Yes

Frequency Mode Yes

Rate Resolution 011 Arings

Dual Crystal Yes

Etch Mode Yes

Crystal Tooling 10-399

Crystal Fail Min Max 40 to 60 MHz 41 to 61 MHz

Power 100-120 200-240~plusmn10 nominal 20W

Operation Environment 0degC ~ 50degC

0 ~ 80 RH non-condensing

0 ~ 2000 meters

Class 1 Equipment

Pollution Degree 2

Rack Dimensions 885mm x 2127mm x 1969mm

Weight 27 kg

Table 4-1 Inficon SQM-160 RateThickness Monitor Specs

84

To the SQM-160 we need to connect an Oscillator We use the Sigma Instruments Remote Oscillator

Ser No 2 268 as shown in figure 4-11

Fig 4-11 Sigma Instruments Remote Oscillator

The connections diagram is shown in figure 4-12

Fig 4-12 SQM-160 Connections Diagram

85

423 Turbo Pump

For our experiments we used the Pfeiffer TCP 015 Electronic Drive Unit shown below in figure 4-13

Table 4-2 shows the technical specifications for this equipment

(a) Front Panel (b) Back Panel

Fig 4-13 Pfeiffer TCP 015 Electronic Drive

Connection Voltage (100V) 90-112

Mains Frequency 5060 Hz

Start-up Current 22 A

Nominal Frequency 1500 Hz

Rotation Speed 10V = 1500Hz plusmn2

Analog Output Current 10 V = 25 A plusmn 5

Rotation Speed Switchpoint 750 Hz

Works Setting 8 min

Permissible Ambient Temperature 0degC ~ 40degC

Dimensions Front Panel 1285mm x 1063mm

Insertion Length 227mm

Weight 27 Kg

Table 4-2 Pfeiffer TCP 015 Electronic Drive Specs

86

The connections diagram is shown in figure 4-14

Fig 4-14Connections Diagram for Pfeiffer TCP 015

To measure the pressure inside the chamber we use the Granville Phillips 375 Convectron Vacuum

Pressure Controller shown in figure 4-15

(a) Front Panel (b) Back Panel

Fig 4-15 Granville Phillips 375 Convectron

87

Its dimensions are shown in figure 4-16

Fig 4-16 Dimensions of Convectron

Table 4-3 shows the technical specifications for this equipment

Table 4-3 Granville Phillips 375 Convectron Vacuum Pressure Controller Specs

88

424 Multimeter

For our experiment we used the Keithley 2000 Digital Multimeter as shown in figure 4-17

(a) Front Panel (b) Back Panel

Fig 4-17 Keithley Model 2000 6-12-Digit Digital Multimeter

Its technical specifications are shown in table 4-4

Table 4-4 Keithley Model 2000 6-12-Digit Digital Multimeter Specs

89

43 Experiment Procedure

1 Connecting together the equipment and the chamber

(1) We first connect the resonator to the thickness monitor and connect the other side to the

chamber

(2) We now connect the flexible tubes to the turbo pump on one side and to the chamber on the

other

(3) We need to check that tubes are tightly connected to avoid any leaks in the vacuum pumping

process which will not allow us to get to our goal of Torr As shown in figure 4-18

(4) Connect the convectron to the system as shown in figure 4-19

Fig 4-18 checking for leaks using alcohol

Fig 4-19 Convectron attached to System

90

(5) Attach the clamps of the Multimeter to the bottom of the chamber as shown in figure 4-20

(6) Place the Quartz crystal in place

(7) Close tight vacuum chamber

(8) Connect all electrical appliances to power source

Fig 4-20 Multimeter Connections

2 Starting up the System

(1) We turn on all the devices as such Check all systems are ready to function Reset all values

that might be left over from previous tests

(2) Start the thickness monitor and set all values for this experiment In our case we got to testing

the system but not actual coating So we used the simulation mode of the thickness monitor as

shown in figure 4-21

Fig 4-21 Simulation Mode

91

(3) Start the turbo pump Make sure the lid on the vacuum chamber is tightly closed

(4) Start convectron and record initial pressure

(5) Start Multimeter and record initial current

3 Coating Process

(1) If we have the deposition material inside the filament boat the power source for the high

current must be started as well

(2) Record all initial values for thickness current pressure

(3) For an ideal experiment we need a thickness of around 101 nm a pressure of Torr and

a current of 300 A

44 Results

From previous experiments we have shown that we can turn a LED into a laser by means of AR

Coating In figure 4-22 shown below we can compare the actual results of a Diode before and after AR

coating From the blue line we can see that when the diode is at a current of 15mA its light will change

from LED to laser and if we look at the red line its critical current is around 30 to 35 mA

Fig 4-22 AR Coating Comparison for Laser Diodes

This means that the light emitted is not as strong as if the diode had been coated because inside the

chamber there must be some excitation first so the reflectivity of both sides inside the diode must be high

So because of the coating in one of the sides we have opened a door and let the light come out so the

critical current is risen as such and will be higher value than that of before the coating

92

In the following figures we can see the difference between before and after coating in a material The

thickness is around 1016 nm for this material

Fig 4-23 Before Coating

Fig 4-24 After Coating

93

Chapter 5 CONCLUSIONS AND RECOMMENDATIONS

51 Conclusions

For the first part of this independent study taking into consideration the data that came out of our

research and that sent by the provider we can say

1 SUM 23 after heat treatment will unexpectedly develop cracking in the middle of the tensile

testing process and suddenly break

2 Itrsquos possible that in the process of heat treatment to the SUM 23 material the treatment was not

uniform and this will create a pre-loaded moment force on one side that pushes on the other side

of the specimen resulting in material deformation

3 In the process of attaching the strain gauges to the materials it is very easy to make errors due to

poor adhesion or sudden removal in the tensile testing process

For our second part of the independent study the following can be made

1 At the beginning of this independent study we had no idea what Bose-Einstein Condensate was

or what was its purpose After much literature we finally comprehended the basic principles to

put into practice for our research

2 Our systemrsquos basic working principles and equipmentrsquos complexity are a little difficult to grasp

but hopefully we were able to understand enough of it

3 Theoretically from relation between the power and current we can know the advantages and

disadvantages of AR Coating

4 We were able to assemble the system and run test on its functions Even though we were able to

do this there is still much more work left to do with this system

52 Recommendations

For the Tensile Testing the following can be said

1 Ask the provider to check on the process of heat treatment on the SUM 23 material and give

them the information we have gathered through our test so they can correct for the mechanical

properties found if any change is needed

2 To avoid the problem of the inaccuracy of the poor adhesion of strain gauges we can attach

multiple strain gauges to the same one specimen so as to correlate data and improve our results

For the AR Coating the following can be said

1 We need to make sure that there are no physical defects on the main body of the chamber so as to

achieve maximum efficiency in the vacuum process If there was then the vacuum will arrive to

certain point and then start to decrease

2 It would be preferable to add some sort of visual aid that will allow the user to check the inside of

the chamber without actually opening it This will help us determine at what times we should

manipulate the current to better evaporate the substrate

94

REFERENCES

[1] A L Window Strain Gauge Technology Elsevier Applied Science London and New York 2nd

Edition 1992

[2] CC Perry and HR Lissner Strain Gauge Primer McGraw-Hill Book Co Inc New York 1955

[3] James W Dally William F Riley McGraw-Hill 1978

[4] University of Colorado Boulder BEC - What is it and where did the idea come from

httpwwwcoloradoeduphysics2000becwhat_is_ithtml

[5] Ultraslow Light amp Bose-Einstein Condensates Two-way Control with Coherent Light amp Atom

Fields Harvard Hau Lab Dr Lene Vestergaard Hau Optics amp Photonics News 16 1995

[6] The Art of Taming Light Ultra-slow and Stopped Light Harvard Hau Lab Dr Lene

Vestergaard Hau Europhysics News 2004

[7] Nonlinear Optics Shocking Superfluids Harvard Hau Lab Dr Lene Vestergaard Hau Nature

Physics 2007

[8] Model P3 Strain Indicator and Recorder Instruction Manual Vishay Micro-Measurements 2005

[9] Granville-Phillips Series 375 Convectron Vacuum Gauge Controller Instruction Manual Brooks

Automation 2008

[10] Effect of Film Thickness on the Validity of the Sauerbrey Equation for Hydrated Polyelectrolyte

Films Vogt Lin Wu White 2004

[11] Quartz Crystal Microbalance Study of DNA Immobilization and Hybridization for DNA Sensor

Development Chang Zhao 2008

[12] Installation of Strain Gages with SR-4 PrecoatAdhesive Vishay Micro-Measurements 2005

[13] Strain Gauge Measurement ndash A Tutorial National Instruments 1998

[14] Correlation between Vickers Hardness Number and Yield Stress of Cold-Formed Products

Yavuz Tekkaya

[15] httpsenwikipediaorg

Page 53: PC Hinge Materials Testing and AR Laser Diode Coating

53

Fig 3-9 Specimen-Strain Gauge Process

3 Tensile Test

(1) Enter the computer application that controls the tensile testing machine

(2) Turn on the tensile testing machine main switch

(3) Adjust the hydraulic pump to go back to its original position

(4) Bring the lowering motor down to a distance enough so as to attach the tensile specimen to the

system open the clamps and secure the specimen

(a)

(5) Connect all the necessary wires to the strain indicator equipment

54

(b)

(6) Start the ascending motor and wait for the expansion

(c)

Fig 3-10 Specimen-Tensile Testing Process

4 Start the Test

(1) Enter the software application and enter some variables needed for the experiment in the

specific screen

(2) Go back to the main screen and press the [測試] (measure) button to start the test and auto

recording in the software

(3) After the specimen breaks the mechanical device will automatically stop and ask the user to

enter the total displacement We take out the specimen from the testing machine and adjust the

machinersquos position back to its original position

(4) Save the results information

(5) Record the results from the strain indicator

34 Results

From this experiment we can get the Poissonrsquos Ratio Youngrsquos Modulus and Yield Strength etc and

because of the slippage phenomenon in the clamp at the moment of the test then the Elastic Limit will

display some yield phenomena So omit any undesirable results we just take the Yield portion of the

results as reference

In the process of the experiment the most important part to attend to is the attaching of the strain

gauge because the gaugersquos purpose is to measure the strain developed during the test and this strain

might be very small If the gaugersquos angle change during the test ie is not well attached this will affect

the accuracy of the measurements of Poissonrsquos ratio and Youngrsquos modulus

55

The materials provided by the manufacturer are SUM 23 and SUM 43 steel round bars and these two

types of materials have been through different heat treatment processes so they can be sub-divided

further into untreated material heat-treated material and black surface heat treated material for the two

materials with heat treatment the treatment process and finished are different In the end we only have

the mechanical properties that were calculated after our research of these materials

All of the specifications are identical to those shown in figure 3-6

341 SUM 23

Fig 3-11 SUM 23 Untreated Material

Number 7 10

Hardness(HRB) 74 75

Yield Stress (MPa) 448 440

Tensile Strength (MPa) 544 560

Poissonrsquos Ratio 029 027

Youngrsquos Modulus (GPa) 203 210

Cut-off Area Shrinking () 42 41

Elongation () 1125 1011

Table 3-5 Mechanical Properties of SUM 23 Untreated

56

Stress-Strain Diagram

(a)

(b)

57

Fig 3-12 Stress-Strain Diagrams for (a) 7 Round Bar and (b) 10 Round Bar

Cut-Off Area

(a)

(b)

Fig 3-13 Cut-Off Area of (a) 7 Round Bar and (b) 10 Round Bar

58

SUM 23 Nickel Round Bar

Fig 3-14 SUM 23 Nickel Material

Number 1 2 3 4

Hardness(HRB) 48 50 49 48

Yield Stress (MPa) 370 370 380 400

Tensile Strength (MPa) 455 451 450 450

Poissonrsquos Ratio 028 046 029 026

Youngrsquos Modulus (GPa) 243 303 246 206

Cut-off Area Shrinking () 803 803 726 601

Elongation () 566 65 602 647

Table 3-6 Mechanical Properties of SUM 23 Nickel

59

Stress-Strain Diagram

(a)

60

(b)

(c)

(d)

61

Fig 3-15 Stress-Strain Diagrams for (a) 1 Round Bar (b) 2 Round Bar (c) 3 Round Bar and (d)

4 Round Bar

Cut-Off Area

(a)

(b)

62

(c)

(d)

Fig 3-16 Cut-Off Area of (a) 1 Round Bar (b) 2 Round Bar (c) 3 Round Bar and (d) 4 Round

Bar

63

SUM 23 Black Surface Round Bar

Fig 3-17 SUM 23 Black Surface Material

Number 1 2 3

Hardness(HRB) 51 50 51

Yield Stress (MPa) 378 371 369

Tensile Strength (MPa) 467 465 464

Poissonrsquos Ratio 03 016 04

Youngrsquos Modulus (GPa) 215 266 266

Cut-off Area Shrinking () 986 94 848

Elongation () 748 805 761

Table 3-7 Mechanical Properties of SUM 23 Black Surface Material

64

Stress-Strain Diagram

(a)

(b)

65

(c)

Fig 3-18 Stress-Strain Diagrams for (a) 1 Round Bar 2 Round Bar and (c) 3 Round Bar

Cut-Off Surface

(a)

66

(b)

(c)

Fig 3-19 Cut-Off Surface of (a) 1 Round Bar 2 Round Bar and (c) 3 Round Bar

67

342 SUM 43

Fig 3-20 Untreated SUM 43 Untreated Material

Number 1 5

Hardness(HRB) 76 75

Yield Stress (MPa) 572 594

Tensile Strength (MPa) 743 785

Poissonrsquos Ratio 027 029

Youngrsquos Modulus (GPa) 200 202

Cut-off Area Shrinking () 338 2944

Elongation () 857 894

Table 3-8 Mechanical Properties of SUM 43 Untreated

68

Stress-Strain Diagrams

(a)

(b)

Fig 3-21 Stress-Strain Diagrams for SUM 43 (a) 1 Round Bar and (b) 5 Round Bar

69

Cut-Off Area

(a)

(b)

Fig 3-22 Cut-Off Area of SUM 43 (a) 1 Round Bar and (b) 5 Round Bar

70

SUM 43 Nickel Round Bar

Fig 3-23 SUM 43 Nickel Material

Number 4 5

Hardness(HRB) 51 50

Yield Stress (MPa) 1580 1544

Tensile Strength (MPa) 1639 1625

Poissonrsquos Ratio 03 028

Youngrsquos Modulus (GPa) 194 201

Cut-off Area Shrinking () 1697 137

Elongation () 376 265

Table 3-9 Mechanical Properties of SUM 43 Nickel

71

Stress-Strain Diagrams

(a)

(b)

Fig 3-24 Stress-Strain Diagrams for (a) 4 Round Bar and (b) 5 Round Bar

72

Cut-Off Area

(a)

(b)

Fig 3-25 Cut-Off Area of (a) 4 Round Bar and (b) 5 Round Bar

73

SUM 43 Black Surface Material

Fig 3-26 SUM 43 Black Surface Material

Number 3 5

Hardness(HRB) 56 56

Yield Stress (MPa) 1416 1361

Tensile Strength (MPa) 1591 1402

Poissonrsquos Ratio 029 031

Youngrsquos Modulus (GPa) 200 202

Cut-off Area Shrinking () 139 124

Elongation () 24 24

Table 3-10 Mechanical Properties of SUM 43 Black Surface Material

74

Stress-Strain Diagrams

0 2 4 6 8 10 12 14

-200

0

200

400

600

800

1000

1200

1400

1600

1800

應力 (MPa)

應變()

(a)

0 2 4 6 8 10

-200

0

200

400

600

800

1000

1200

1400

1600

應力

(MPa)

位移 ()

(b)

Fig 3-27 Stress-Strain Diagrams for (a) 3 Round Bar and (b) 5 Round Bar

(Note These curves were formulated using Visual Solutions Inc VisSim Software)

75

Cut-Off Area

(a)

(b)

Fig 3-28 Cut-Off Area of (a) 3 Round Bar and (b) 5 Round Bar

76

The force value (N) was retrieved from the Universal Testing Machine

The Poissonrsquos Ratio (ε) is calculated as

ε =

the values for the Poissonrsquos Ratio are in average around 0297

The Youngrsquos Modulus (E) is calculated as

E =

Where

Stress =

Cross-sectional Area =

where D is the Diameter

The value for D was in average around 1258 mm

The values shown by the computer because there is Slippage phenomena between the Clamp and the

specimen will not be taken into consideration for the elongation strain and Youngrsquos modulus and we will

refer to the values that we have meticulously calculated

77

Chapter 4 AR COATING IN DEPTH

41 Experimentrsquos Purpose and Principles

By means of a vacuum chamber and several other instruments we intend to apply Anti-Reflective

Coating using deposition process to a laser diode and in this way reduce its refraction so as to make it

lose less light in the process of amplification and we can control certain wavelengths we want produced

for certain desired applications in our case we are attempting to re-create a Bose-Einstein Condensate

An optimal BEC apparatus is shown in figure 4-1

Fig 4-1 BEC Apparatus

The main point of this experiment is to build a vacuum chamber system attach all the instrumentation

needed (Vacuum pump deposition meter and voltmeter) and use it to apply AR coating to a laser diode

After we have accomplished the AR coating other team will be in charge of designing the BEC apparatus

and use the results of our research

78

42 Experimentrsquos Equipment

421 Vacuum Chamber

For this research we designed a vacuum chamber whose main body is shown in figure 4-2 Its

dimensions are

Width 240 mm

Length 240 mm

Height 200 mm

Outer Diameter 4 in

Inner Diameter 15 in

Fig 4-2 Vacuum Chamber Main Body

The chamber is made up of 6 pass ways pass way A is the connection with the Laser Deposition

Equipment pass way B is the connection with the Turbo Pump and pass way C is for the connection with

the Deposition Source

A

C

B

79

Pass way C is for the deposition source as mentioned above This is a system where a thermal

resistance is heated by passing a high current through it which heats up a filament boat (made of tungsten)

where the material to be evaporated is place We control the temperature as such that the material will

evaporate and the heat will not cause the filament boat to crack

Because P = Isup2 R (where P is power I is current and R is resistance) to avoid the current to flow

where it is not desired we decided that the material for the Thermocouple shown in figure 4-3 should be

Copper ᴓ 63 mm We choose it that way because Copper has very good heat dissipation characteristics

and the resistance value is low It can reduce the value of the current enough to make the thermocouple to

create heat

Fig 4-3 Thermocouple

To the thermocouple we attach the tungsten filament boat We need to take notice of materials to be

used in this design because when using high current the tungsten filament boar will heat up and so the

material must be able to keep up with the heating potential of tungsten and has a low coefficient of heat

dissipation to avoid the tungsten to fail when heating up and therefore not evaporating Considering all

this we decide to use Stainless Steel

Because this clamp will be assembled inside the chamber after many revisions it was determined it

will have the shape shown in figure 4-4

Fig 4-4 Filament Boat Clamp Design

80

For the tungsten filament boat we bought the product from a distributor The dimensions are

Length 100 mm

Width 10 mm

Height 1 mm

Our thermocouple is 15 in but the pass way C is 4 in so we need to attach a Flange that connects

15in to 4in Because these specifications are quite difficult to achieve by Milling we had to use

electrical wire cutting

For the laser clamping system where the laser that is going to be AR coated will be placed will be

connected to pass way A the assembly is shown in figure 4-5 below

Fig 4-5 Cover Assembly

For this design we used an O-ring instead of a gasket so as to save time The design of the assembly

where the laser will be placed is shown in figure 4-6

Fig 4-6 Upper Cover Inner Assembly

D

E

F

81

Point D is the plate in the assembly where the laser diode will be fixed Because of the easy

processing we decide to use Aluminum and it is screwed to the top cover Point E is the connection for

the Quartz crystal resonator and it is designed in the same as point F in this way the results of the quartz

microbalance system will be more accurate in real time Point F is the final resting place for the laser

diode We use a Thor Labs Base with dimensions of ᴓ 9mm and ᴓ 56mm for two different size laser

diodes It just needs to be plugged in for easy installation

From figure 4-6 we know that the system needs signal system connections and because of the

change in temperature inside the chamber this could affect the functioning of the quartz microbalance so

we also need to install water tubes for cooling This is shown in figure 4-7 below

Fig 4-7 Diagram of Upper Cover Connections

In figure 4-8 we show the Feed through connections and their functions

Fig 4-8 Feed through Diagram

82

1 SQM-160 wire 5 Laser Connection 1 (Vin)

2 SQM-160 (G) 6 Laser Connection 2 (G)

3 K-Type-1 7 Laser Connection 3 (PD)

4 K-Type-2 8 Not In Use

The fully assembled chamber is shown in figure 4-9

Fig 4-9 Fully Assembled Chamber

422 Quartz Crystal Microbalance

For measuring the deposition on our target for coating we used the Inficon SQM-160 RateThickness

Monitor It is an easy to use instrument for measuring many types of thin-film coatings as shown in

figure 4-10

(a) Front Panel (b) Back Panel

Fig 4-10 Inficon SQM-160

83

Table 4-1 shows the technical specifications for this equipment

Number of sensors 2 Standard 4 additional optional

Sensor Frequency Range 40 MHz ~ 60 MHz

Reference Frequency Accuracy 002

Thickness Display Resolution 1 Aring

Thickness Resolution 015 Aring (Std) 0037 Aring (Hi Res)

Density of Stored Films 05-9999 gmcc

Tooling 10-399

Z-Factor 010-1000

Final Thickness 0000-9999k Aring

Measurement Period 15 to 2 sec

Simulation Mode Yes

Frequency Mode Yes

Rate Resolution 011 Arings

Dual Crystal Yes

Etch Mode Yes

Crystal Tooling 10-399

Crystal Fail Min Max 40 to 60 MHz 41 to 61 MHz

Power 100-120 200-240~plusmn10 nominal 20W

Operation Environment 0degC ~ 50degC

0 ~ 80 RH non-condensing

0 ~ 2000 meters

Class 1 Equipment

Pollution Degree 2

Rack Dimensions 885mm x 2127mm x 1969mm

Weight 27 kg

Table 4-1 Inficon SQM-160 RateThickness Monitor Specs

84

To the SQM-160 we need to connect an Oscillator We use the Sigma Instruments Remote Oscillator

Ser No 2 268 as shown in figure 4-11

Fig 4-11 Sigma Instruments Remote Oscillator

The connections diagram is shown in figure 4-12

Fig 4-12 SQM-160 Connections Diagram

85

423 Turbo Pump

For our experiments we used the Pfeiffer TCP 015 Electronic Drive Unit shown below in figure 4-13

Table 4-2 shows the technical specifications for this equipment

(a) Front Panel (b) Back Panel

Fig 4-13 Pfeiffer TCP 015 Electronic Drive

Connection Voltage (100V) 90-112

Mains Frequency 5060 Hz

Start-up Current 22 A

Nominal Frequency 1500 Hz

Rotation Speed 10V = 1500Hz plusmn2

Analog Output Current 10 V = 25 A plusmn 5

Rotation Speed Switchpoint 750 Hz

Works Setting 8 min

Permissible Ambient Temperature 0degC ~ 40degC

Dimensions Front Panel 1285mm x 1063mm

Insertion Length 227mm

Weight 27 Kg

Table 4-2 Pfeiffer TCP 015 Electronic Drive Specs

86

The connections diagram is shown in figure 4-14

Fig 4-14Connections Diagram for Pfeiffer TCP 015

To measure the pressure inside the chamber we use the Granville Phillips 375 Convectron Vacuum

Pressure Controller shown in figure 4-15

(a) Front Panel (b) Back Panel

Fig 4-15 Granville Phillips 375 Convectron

87

Its dimensions are shown in figure 4-16

Fig 4-16 Dimensions of Convectron

Table 4-3 shows the technical specifications for this equipment

Table 4-3 Granville Phillips 375 Convectron Vacuum Pressure Controller Specs

88

424 Multimeter

For our experiment we used the Keithley 2000 Digital Multimeter as shown in figure 4-17

(a) Front Panel (b) Back Panel

Fig 4-17 Keithley Model 2000 6-12-Digit Digital Multimeter

Its technical specifications are shown in table 4-4

Table 4-4 Keithley Model 2000 6-12-Digit Digital Multimeter Specs

89

43 Experiment Procedure

1 Connecting together the equipment and the chamber

(1) We first connect the resonator to the thickness monitor and connect the other side to the

chamber

(2) We now connect the flexible tubes to the turbo pump on one side and to the chamber on the

other

(3) We need to check that tubes are tightly connected to avoid any leaks in the vacuum pumping

process which will not allow us to get to our goal of Torr As shown in figure 4-18

(4) Connect the convectron to the system as shown in figure 4-19

Fig 4-18 checking for leaks using alcohol

Fig 4-19 Convectron attached to System

90

(5) Attach the clamps of the Multimeter to the bottom of the chamber as shown in figure 4-20

(6) Place the Quartz crystal in place

(7) Close tight vacuum chamber

(8) Connect all electrical appliances to power source

Fig 4-20 Multimeter Connections

2 Starting up the System

(1) We turn on all the devices as such Check all systems are ready to function Reset all values

that might be left over from previous tests

(2) Start the thickness monitor and set all values for this experiment In our case we got to testing

the system but not actual coating So we used the simulation mode of the thickness monitor as

shown in figure 4-21

Fig 4-21 Simulation Mode

91

(3) Start the turbo pump Make sure the lid on the vacuum chamber is tightly closed

(4) Start convectron and record initial pressure

(5) Start Multimeter and record initial current

3 Coating Process

(1) If we have the deposition material inside the filament boat the power source for the high

current must be started as well

(2) Record all initial values for thickness current pressure

(3) For an ideal experiment we need a thickness of around 101 nm a pressure of Torr and

a current of 300 A

44 Results

From previous experiments we have shown that we can turn a LED into a laser by means of AR

Coating In figure 4-22 shown below we can compare the actual results of a Diode before and after AR

coating From the blue line we can see that when the diode is at a current of 15mA its light will change

from LED to laser and if we look at the red line its critical current is around 30 to 35 mA

Fig 4-22 AR Coating Comparison for Laser Diodes

This means that the light emitted is not as strong as if the diode had been coated because inside the

chamber there must be some excitation first so the reflectivity of both sides inside the diode must be high

So because of the coating in one of the sides we have opened a door and let the light come out so the

critical current is risen as such and will be higher value than that of before the coating

92

In the following figures we can see the difference between before and after coating in a material The

thickness is around 1016 nm for this material

Fig 4-23 Before Coating

Fig 4-24 After Coating

93

Chapter 5 CONCLUSIONS AND RECOMMENDATIONS

51 Conclusions

For the first part of this independent study taking into consideration the data that came out of our

research and that sent by the provider we can say

1 SUM 23 after heat treatment will unexpectedly develop cracking in the middle of the tensile

testing process and suddenly break

2 Itrsquos possible that in the process of heat treatment to the SUM 23 material the treatment was not

uniform and this will create a pre-loaded moment force on one side that pushes on the other side

of the specimen resulting in material deformation

3 In the process of attaching the strain gauges to the materials it is very easy to make errors due to

poor adhesion or sudden removal in the tensile testing process

For our second part of the independent study the following can be made

1 At the beginning of this independent study we had no idea what Bose-Einstein Condensate was

or what was its purpose After much literature we finally comprehended the basic principles to

put into practice for our research

2 Our systemrsquos basic working principles and equipmentrsquos complexity are a little difficult to grasp

but hopefully we were able to understand enough of it

3 Theoretically from relation between the power and current we can know the advantages and

disadvantages of AR Coating

4 We were able to assemble the system and run test on its functions Even though we were able to

do this there is still much more work left to do with this system

52 Recommendations

For the Tensile Testing the following can be said

1 Ask the provider to check on the process of heat treatment on the SUM 23 material and give

them the information we have gathered through our test so they can correct for the mechanical

properties found if any change is needed

2 To avoid the problem of the inaccuracy of the poor adhesion of strain gauges we can attach

multiple strain gauges to the same one specimen so as to correlate data and improve our results

For the AR Coating the following can be said

1 We need to make sure that there are no physical defects on the main body of the chamber so as to

achieve maximum efficiency in the vacuum process If there was then the vacuum will arrive to

certain point and then start to decrease

2 It would be preferable to add some sort of visual aid that will allow the user to check the inside of

the chamber without actually opening it This will help us determine at what times we should

manipulate the current to better evaporate the substrate

94

REFERENCES

[1] A L Window Strain Gauge Technology Elsevier Applied Science London and New York 2nd

Edition 1992

[2] CC Perry and HR Lissner Strain Gauge Primer McGraw-Hill Book Co Inc New York 1955

[3] James W Dally William F Riley McGraw-Hill 1978

[4] University of Colorado Boulder BEC - What is it and where did the idea come from

httpwwwcoloradoeduphysics2000becwhat_is_ithtml

[5] Ultraslow Light amp Bose-Einstein Condensates Two-way Control with Coherent Light amp Atom

Fields Harvard Hau Lab Dr Lene Vestergaard Hau Optics amp Photonics News 16 1995

[6] The Art of Taming Light Ultra-slow and Stopped Light Harvard Hau Lab Dr Lene

Vestergaard Hau Europhysics News 2004

[7] Nonlinear Optics Shocking Superfluids Harvard Hau Lab Dr Lene Vestergaard Hau Nature

Physics 2007

[8] Model P3 Strain Indicator and Recorder Instruction Manual Vishay Micro-Measurements 2005

[9] Granville-Phillips Series 375 Convectron Vacuum Gauge Controller Instruction Manual Brooks

Automation 2008

[10] Effect of Film Thickness on the Validity of the Sauerbrey Equation for Hydrated Polyelectrolyte

Films Vogt Lin Wu White 2004

[11] Quartz Crystal Microbalance Study of DNA Immobilization and Hybridization for DNA Sensor

Development Chang Zhao 2008

[12] Installation of Strain Gages with SR-4 PrecoatAdhesive Vishay Micro-Measurements 2005

[13] Strain Gauge Measurement ndash A Tutorial National Instruments 1998

[14] Correlation between Vickers Hardness Number and Yield Stress of Cold-Formed Products

Yavuz Tekkaya

[15] httpsenwikipediaorg

Page 54: PC Hinge Materials Testing and AR Laser Diode Coating

54

(b)

(6) Start the ascending motor and wait for the expansion

(c)

Fig 3-10 Specimen-Tensile Testing Process

4 Start the Test

(1) Enter the software application and enter some variables needed for the experiment in the

specific screen

(2) Go back to the main screen and press the [測試] (measure) button to start the test and auto

recording in the software

(3) After the specimen breaks the mechanical device will automatically stop and ask the user to

enter the total displacement We take out the specimen from the testing machine and adjust the

machinersquos position back to its original position

(4) Save the results information

(5) Record the results from the strain indicator

34 Results

From this experiment we can get the Poissonrsquos Ratio Youngrsquos Modulus and Yield Strength etc and

because of the slippage phenomenon in the clamp at the moment of the test then the Elastic Limit will

display some yield phenomena So omit any undesirable results we just take the Yield portion of the

results as reference

In the process of the experiment the most important part to attend to is the attaching of the strain

gauge because the gaugersquos purpose is to measure the strain developed during the test and this strain

might be very small If the gaugersquos angle change during the test ie is not well attached this will affect

the accuracy of the measurements of Poissonrsquos ratio and Youngrsquos modulus

55

The materials provided by the manufacturer are SUM 23 and SUM 43 steel round bars and these two

types of materials have been through different heat treatment processes so they can be sub-divided

further into untreated material heat-treated material and black surface heat treated material for the two

materials with heat treatment the treatment process and finished are different In the end we only have

the mechanical properties that were calculated after our research of these materials

All of the specifications are identical to those shown in figure 3-6

341 SUM 23

Fig 3-11 SUM 23 Untreated Material

Number 7 10

Hardness(HRB) 74 75

Yield Stress (MPa) 448 440

Tensile Strength (MPa) 544 560

Poissonrsquos Ratio 029 027

Youngrsquos Modulus (GPa) 203 210

Cut-off Area Shrinking () 42 41

Elongation () 1125 1011

Table 3-5 Mechanical Properties of SUM 23 Untreated

56

Stress-Strain Diagram

(a)

(b)

57

Fig 3-12 Stress-Strain Diagrams for (a) 7 Round Bar and (b) 10 Round Bar

Cut-Off Area

(a)

(b)

Fig 3-13 Cut-Off Area of (a) 7 Round Bar and (b) 10 Round Bar

58

SUM 23 Nickel Round Bar

Fig 3-14 SUM 23 Nickel Material

Number 1 2 3 4

Hardness(HRB) 48 50 49 48

Yield Stress (MPa) 370 370 380 400

Tensile Strength (MPa) 455 451 450 450

Poissonrsquos Ratio 028 046 029 026

Youngrsquos Modulus (GPa) 243 303 246 206

Cut-off Area Shrinking () 803 803 726 601

Elongation () 566 65 602 647

Table 3-6 Mechanical Properties of SUM 23 Nickel

59

Stress-Strain Diagram

(a)

60

(b)

(c)

(d)

61

Fig 3-15 Stress-Strain Diagrams for (a) 1 Round Bar (b) 2 Round Bar (c) 3 Round Bar and (d)

4 Round Bar

Cut-Off Area

(a)

(b)

62

(c)

(d)

Fig 3-16 Cut-Off Area of (a) 1 Round Bar (b) 2 Round Bar (c) 3 Round Bar and (d) 4 Round

Bar

63

SUM 23 Black Surface Round Bar

Fig 3-17 SUM 23 Black Surface Material

Number 1 2 3

Hardness(HRB) 51 50 51

Yield Stress (MPa) 378 371 369

Tensile Strength (MPa) 467 465 464

Poissonrsquos Ratio 03 016 04

Youngrsquos Modulus (GPa) 215 266 266

Cut-off Area Shrinking () 986 94 848

Elongation () 748 805 761

Table 3-7 Mechanical Properties of SUM 23 Black Surface Material

64

Stress-Strain Diagram

(a)

(b)

65

(c)

Fig 3-18 Stress-Strain Diagrams for (a) 1 Round Bar 2 Round Bar and (c) 3 Round Bar

Cut-Off Surface

(a)

66

(b)

(c)

Fig 3-19 Cut-Off Surface of (a) 1 Round Bar 2 Round Bar and (c) 3 Round Bar

67

342 SUM 43

Fig 3-20 Untreated SUM 43 Untreated Material

Number 1 5

Hardness(HRB) 76 75

Yield Stress (MPa) 572 594

Tensile Strength (MPa) 743 785

Poissonrsquos Ratio 027 029

Youngrsquos Modulus (GPa) 200 202

Cut-off Area Shrinking () 338 2944

Elongation () 857 894

Table 3-8 Mechanical Properties of SUM 43 Untreated

68

Stress-Strain Diagrams

(a)

(b)

Fig 3-21 Stress-Strain Diagrams for SUM 43 (a) 1 Round Bar and (b) 5 Round Bar

69

Cut-Off Area

(a)

(b)

Fig 3-22 Cut-Off Area of SUM 43 (a) 1 Round Bar and (b) 5 Round Bar

70

SUM 43 Nickel Round Bar

Fig 3-23 SUM 43 Nickel Material

Number 4 5

Hardness(HRB) 51 50

Yield Stress (MPa) 1580 1544

Tensile Strength (MPa) 1639 1625

Poissonrsquos Ratio 03 028

Youngrsquos Modulus (GPa) 194 201

Cut-off Area Shrinking () 1697 137

Elongation () 376 265

Table 3-9 Mechanical Properties of SUM 43 Nickel

71

Stress-Strain Diagrams

(a)

(b)

Fig 3-24 Stress-Strain Diagrams for (a) 4 Round Bar and (b) 5 Round Bar

72

Cut-Off Area

(a)

(b)

Fig 3-25 Cut-Off Area of (a) 4 Round Bar and (b) 5 Round Bar

73

SUM 43 Black Surface Material

Fig 3-26 SUM 43 Black Surface Material

Number 3 5

Hardness(HRB) 56 56

Yield Stress (MPa) 1416 1361

Tensile Strength (MPa) 1591 1402

Poissonrsquos Ratio 029 031

Youngrsquos Modulus (GPa) 200 202

Cut-off Area Shrinking () 139 124

Elongation () 24 24

Table 3-10 Mechanical Properties of SUM 43 Black Surface Material

74

Stress-Strain Diagrams

0 2 4 6 8 10 12 14

-200

0

200

400

600

800

1000

1200

1400

1600

1800

應力 (MPa)

應變()

(a)

0 2 4 6 8 10

-200

0

200

400

600

800

1000

1200

1400

1600

應力

(MPa)

位移 ()

(b)

Fig 3-27 Stress-Strain Diagrams for (a) 3 Round Bar and (b) 5 Round Bar

(Note These curves were formulated using Visual Solutions Inc VisSim Software)

75

Cut-Off Area

(a)

(b)

Fig 3-28 Cut-Off Area of (a) 3 Round Bar and (b) 5 Round Bar

76

The force value (N) was retrieved from the Universal Testing Machine

The Poissonrsquos Ratio (ε) is calculated as

ε =

the values for the Poissonrsquos Ratio are in average around 0297

The Youngrsquos Modulus (E) is calculated as

E =

Where

Stress =

Cross-sectional Area =

where D is the Diameter

The value for D was in average around 1258 mm

The values shown by the computer because there is Slippage phenomena between the Clamp and the

specimen will not be taken into consideration for the elongation strain and Youngrsquos modulus and we will

refer to the values that we have meticulously calculated

77

Chapter 4 AR COATING IN DEPTH

41 Experimentrsquos Purpose and Principles

By means of a vacuum chamber and several other instruments we intend to apply Anti-Reflective

Coating using deposition process to a laser diode and in this way reduce its refraction so as to make it

lose less light in the process of amplification and we can control certain wavelengths we want produced

for certain desired applications in our case we are attempting to re-create a Bose-Einstein Condensate

An optimal BEC apparatus is shown in figure 4-1

Fig 4-1 BEC Apparatus

The main point of this experiment is to build a vacuum chamber system attach all the instrumentation

needed (Vacuum pump deposition meter and voltmeter) and use it to apply AR coating to a laser diode

After we have accomplished the AR coating other team will be in charge of designing the BEC apparatus

and use the results of our research

78

42 Experimentrsquos Equipment

421 Vacuum Chamber

For this research we designed a vacuum chamber whose main body is shown in figure 4-2 Its

dimensions are

Width 240 mm

Length 240 mm

Height 200 mm

Outer Diameter 4 in

Inner Diameter 15 in

Fig 4-2 Vacuum Chamber Main Body

The chamber is made up of 6 pass ways pass way A is the connection with the Laser Deposition

Equipment pass way B is the connection with the Turbo Pump and pass way C is for the connection with

the Deposition Source

A

C

B

79

Pass way C is for the deposition source as mentioned above This is a system where a thermal

resistance is heated by passing a high current through it which heats up a filament boat (made of tungsten)

where the material to be evaporated is place We control the temperature as such that the material will

evaporate and the heat will not cause the filament boat to crack

Because P = Isup2 R (where P is power I is current and R is resistance) to avoid the current to flow

where it is not desired we decided that the material for the Thermocouple shown in figure 4-3 should be

Copper ᴓ 63 mm We choose it that way because Copper has very good heat dissipation characteristics

and the resistance value is low It can reduce the value of the current enough to make the thermocouple to

create heat

Fig 4-3 Thermocouple

To the thermocouple we attach the tungsten filament boat We need to take notice of materials to be

used in this design because when using high current the tungsten filament boar will heat up and so the

material must be able to keep up with the heating potential of tungsten and has a low coefficient of heat

dissipation to avoid the tungsten to fail when heating up and therefore not evaporating Considering all

this we decide to use Stainless Steel

Because this clamp will be assembled inside the chamber after many revisions it was determined it

will have the shape shown in figure 4-4

Fig 4-4 Filament Boat Clamp Design

80

For the tungsten filament boat we bought the product from a distributor The dimensions are

Length 100 mm

Width 10 mm

Height 1 mm

Our thermocouple is 15 in but the pass way C is 4 in so we need to attach a Flange that connects

15in to 4in Because these specifications are quite difficult to achieve by Milling we had to use

electrical wire cutting

For the laser clamping system where the laser that is going to be AR coated will be placed will be

connected to pass way A the assembly is shown in figure 4-5 below

Fig 4-5 Cover Assembly

For this design we used an O-ring instead of a gasket so as to save time The design of the assembly

where the laser will be placed is shown in figure 4-6

Fig 4-6 Upper Cover Inner Assembly

D

E

F

81

Point D is the plate in the assembly where the laser diode will be fixed Because of the easy

processing we decide to use Aluminum and it is screwed to the top cover Point E is the connection for

the Quartz crystal resonator and it is designed in the same as point F in this way the results of the quartz

microbalance system will be more accurate in real time Point F is the final resting place for the laser

diode We use a Thor Labs Base with dimensions of ᴓ 9mm and ᴓ 56mm for two different size laser

diodes It just needs to be plugged in for easy installation

From figure 4-6 we know that the system needs signal system connections and because of the

change in temperature inside the chamber this could affect the functioning of the quartz microbalance so

we also need to install water tubes for cooling This is shown in figure 4-7 below

Fig 4-7 Diagram of Upper Cover Connections

In figure 4-8 we show the Feed through connections and their functions

Fig 4-8 Feed through Diagram

82

1 SQM-160 wire 5 Laser Connection 1 (Vin)

2 SQM-160 (G) 6 Laser Connection 2 (G)

3 K-Type-1 7 Laser Connection 3 (PD)

4 K-Type-2 8 Not In Use

The fully assembled chamber is shown in figure 4-9

Fig 4-9 Fully Assembled Chamber

422 Quartz Crystal Microbalance

For measuring the deposition on our target for coating we used the Inficon SQM-160 RateThickness

Monitor It is an easy to use instrument for measuring many types of thin-film coatings as shown in

figure 4-10

(a) Front Panel (b) Back Panel

Fig 4-10 Inficon SQM-160

83

Table 4-1 shows the technical specifications for this equipment

Number of sensors 2 Standard 4 additional optional

Sensor Frequency Range 40 MHz ~ 60 MHz

Reference Frequency Accuracy 002

Thickness Display Resolution 1 Aring

Thickness Resolution 015 Aring (Std) 0037 Aring (Hi Res)

Density of Stored Films 05-9999 gmcc

Tooling 10-399

Z-Factor 010-1000

Final Thickness 0000-9999k Aring

Measurement Period 15 to 2 sec

Simulation Mode Yes

Frequency Mode Yes

Rate Resolution 011 Arings

Dual Crystal Yes

Etch Mode Yes

Crystal Tooling 10-399

Crystal Fail Min Max 40 to 60 MHz 41 to 61 MHz

Power 100-120 200-240~plusmn10 nominal 20W

Operation Environment 0degC ~ 50degC

0 ~ 80 RH non-condensing

0 ~ 2000 meters

Class 1 Equipment

Pollution Degree 2

Rack Dimensions 885mm x 2127mm x 1969mm

Weight 27 kg

Table 4-1 Inficon SQM-160 RateThickness Monitor Specs

84

To the SQM-160 we need to connect an Oscillator We use the Sigma Instruments Remote Oscillator

Ser No 2 268 as shown in figure 4-11

Fig 4-11 Sigma Instruments Remote Oscillator

The connections diagram is shown in figure 4-12

Fig 4-12 SQM-160 Connections Diagram

85

423 Turbo Pump

For our experiments we used the Pfeiffer TCP 015 Electronic Drive Unit shown below in figure 4-13

Table 4-2 shows the technical specifications for this equipment

(a) Front Panel (b) Back Panel

Fig 4-13 Pfeiffer TCP 015 Electronic Drive

Connection Voltage (100V) 90-112

Mains Frequency 5060 Hz

Start-up Current 22 A

Nominal Frequency 1500 Hz

Rotation Speed 10V = 1500Hz plusmn2

Analog Output Current 10 V = 25 A plusmn 5

Rotation Speed Switchpoint 750 Hz

Works Setting 8 min

Permissible Ambient Temperature 0degC ~ 40degC

Dimensions Front Panel 1285mm x 1063mm

Insertion Length 227mm

Weight 27 Kg

Table 4-2 Pfeiffer TCP 015 Electronic Drive Specs

86

The connections diagram is shown in figure 4-14

Fig 4-14Connections Diagram for Pfeiffer TCP 015

To measure the pressure inside the chamber we use the Granville Phillips 375 Convectron Vacuum

Pressure Controller shown in figure 4-15

(a) Front Panel (b) Back Panel

Fig 4-15 Granville Phillips 375 Convectron

87

Its dimensions are shown in figure 4-16

Fig 4-16 Dimensions of Convectron

Table 4-3 shows the technical specifications for this equipment

Table 4-3 Granville Phillips 375 Convectron Vacuum Pressure Controller Specs

88

424 Multimeter

For our experiment we used the Keithley 2000 Digital Multimeter as shown in figure 4-17

(a) Front Panel (b) Back Panel

Fig 4-17 Keithley Model 2000 6-12-Digit Digital Multimeter

Its technical specifications are shown in table 4-4

Table 4-4 Keithley Model 2000 6-12-Digit Digital Multimeter Specs

89

43 Experiment Procedure

1 Connecting together the equipment and the chamber

(1) We first connect the resonator to the thickness monitor and connect the other side to the

chamber

(2) We now connect the flexible tubes to the turbo pump on one side and to the chamber on the

other

(3) We need to check that tubes are tightly connected to avoid any leaks in the vacuum pumping

process which will not allow us to get to our goal of Torr As shown in figure 4-18

(4) Connect the convectron to the system as shown in figure 4-19

Fig 4-18 checking for leaks using alcohol

Fig 4-19 Convectron attached to System

90

(5) Attach the clamps of the Multimeter to the bottom of the chamber as shown in figure 4-20

(6) Place the Quartz crystal in place

(7) Close tight vacuum chamber

(8) Connect all electrical appliances to power source

Fig 4-20 Multimeter Connections

2 Starting up the System

(1) We turn on all the devices as such Check all systems are ready to function Reset all values

that might be left over from previous tests

(2) Start the thickness monitor and set all values for this experiment In our case we got to testing

the system but not actual coating So we used the simulation mode of the thickness monitor as

shown in figure 4-21

Fig 4-21 Simulation Mode

91

(3) Start the turbo pump Make sure the lid on the vacuum chamber is tightly closed

(4) Start convectron and record initial pressure

(5) Start Multimeter and record initial current

3 Coating Process

(1) If we have the deposition material inside the filament boat the power source for the high

current must be started as well

(2) Record all initial values for thickness current pressure

(3) For an ideal experiment we need a thickness of around 101 nm a pressure of Torr and

a current of 300 A

44 Results

From previous experiments we have shown that we can turn a LED into a laser by means of AR

Coating In figure 4-22 shown below we can compare the actual results of a Diode before and after AR

coating From the blue line we can see that when the diode is at a current of 15mA its light will change

from LED to laser and if we look at the red line its critical current is around 30 to 35 mA

Fig 4-22 AR Coating Comparison for Laser Diodes

This means that the light emitted is not as strong as if the diode had been coated because inside the

chamber there must be some excitation first so the reflectivity of both sides inside the diode must be high

So because of the coating in one of the sides we have opened a door and let the light come out so the

critical current is risen as such and will be higher value than that of before the coating

92

In the following figures we can see the difference between before and after coating in a material The

thickness is around 1016 nm for this material

Fig 4-23 Before Coating

Fig 4-24 After Coating

93

Chapter 5 CONCLUSIONS AND RECOMMENDATIONS

51 Conclusions

For the first part of this independent study taking into consideration the data that came out of our

research and that sent by the provider we can say

1 SUM 23 after heat treatment will unexpectedly develop cracking in the middle of the tensile

testing process and suddenly break

2 Itrsquos possible that in the process of heat treatment to the SUM 23 material the treatment was not

uniform and this will create a pre-loaded moment force on one side that pushes on the other side

of the specimen resulting in material deformation

3 In the process of attaching the strain gauges to the materials it is very easy to make errors due to

poor adhesion or sudden removal in the tensile testing process

For our second part of the independent study the following can be made

1 At the beginning of this independent study we had no idea what Bose-Einstein Condensate was

or what was its purpose After much literature we finally comprehended the basic principles to

put into practice for our research

2 Our systemrsquos basic working principles and equipmentrsquos complexity are a little difficult to grasp

but hopefully we were able to understand enough of it

3 Theoretically from relation between the power and current we can know the advantages and

disadvantages of AR Coating

4 We were able to assemble the system and run test on its functions Even though we were able to

do this there is still much more work left to do with this system

52 Recommendations

For the Tensile Testing the following can be said

1 Ask the provider to check on the process of heat treatment on the SUM 23 material and give

them the information we have gathered through our test so they can correct for the mechanical

properties found if any change is needed

2 To avoid the problem of the inaccuracy of the poor adhesion of strain gauges we can attach

multiple strain gauges to the same one specimen so as to correlate data and improve our results

For the AR Coating the following can be said

1 We need to make sure that there are no physical defects on the main body of the chamber so as to

achieve maximum efficiency in the vacuum process If there was then the vacuum will arrive to

certain point and then start to decrease

2 It would be preferable to add some sort of visual aid that will allow the user to check the inside of

the chamber without actually opening it This will help us determine at what times we should

manipulate the current to better evaporate the substrate

94

REFERENCES

[1] A L Window Strain Gauge Technology Elsevier Applied Science London and New York 2nd

Edition 1992

[2] CC Perry and HR Lissner Strain Gauge Primer McGraw-Hill Book Co Inc New York 1955

[3] James W Dally William F Riley McGraw-Hill 1978

[4] University of Colorado Boulder BEC - What is it and where did the idea come from

httpwwwcoloradoeduphysics2000becwhat_is_ithtml

[5] Ultraslow Light amp Bose-Einstein Condensates Two-way Control with Coherent Light amp Atom

Fields Harvard Hau Lab Dr Lene Vestergaard Hau Optics amp Photonics News 16 1995

[6] The Art of Taming Light Ultra-slow and Stopped Light Harvard Hau Lab Dr Lene

Vestergaard Hau Europhysics News 2004

[7] Nonlinear Optics Shocking Superfluids Harvard Hau Lab Dr Lene Vestergaard Hau Nature

Physics 2007

[8] Model P3 Strain Indicator and Recorder Instruction Manual Vishay Micro-Measurements 2005

[9] Granville-Phillips Series 375 Convectron Vacuum Gauge Controller Instruction Manual Brooks

Automation 2008

[10] Effect of Film Thickness on the Validity of the Sauerbrey Equation for Hydrated Polyelectrolyte

Films Vogt Lin Wu White 2004

[11] Quartz Crystal Microbalance Study of DNA Immobilization and Hybridization for DNA Sensor

Development Chang Zhao 2008

[12] Installation of Strain Gages with SR-4 PrecoatAdhesive Vishay Micro-Measurements 2005

[13] Strain Gauge Measurement ndash A Tutorial National Instruments 1998

[14] Correlation between Vickers Hardness Number and Yield Stress of Cold-Formed Products

Yavuz Tekkaya

[15] httpsenwikipediaorg

Page 55: PC Hinge Materials Testing and AR Laser Diode Coating

55

The materials provided by the manufacturer are SUM 23 and SUM 43 steel round bars and these two

types of materials have been through different heat treatment processes so they can be sub-divided

further into untreated material heat-treated material and black surface heat treated material for the two

materials with heat treatment the treatment process and finished are different In the end we only have

the mechanical properties that were calculated after our research of these materials

All of the specifications are identical to those shown in figure 3-6

341 SUM 23

Fig 3-11 SUM 23 Untreated Material

Number 7 10

Hardness(HRB) 74 75

Yield Stress (MPa) 448 440

Tensile Strength (MPa) 544 560

Poissonrsquos Ratio 029 027

Youngrsquos Modulus (GPa) 203 210

Cut-off Area Shrinking () 42 41

Elongation () 1125 1011

Table 3-5 Mechanical Properties of SUM 23 Untreated

56

Stress-Strain Diagram

(a)

(b)

57

Fig 3-12 Stress-Strain Diagrams for (a) 7 Round Bar and (b) 10 Round Bar

Cut-Off Area

(a)

(b)

Fig 3-13 Cut-Off Area of (a) 7 Round Bar and (b) 10 Round Bar

58

SUM 23 Nickel Round Bar

Fig 3-14 SUM 23 Nickel Material

Number 1 2 3 4

Hardness(HRB) 48 50 49 48

Yield Stress (MPa) 370 370 380 400

Tensile Strength (MPa) 455 451 450 450

Poissonrsquos Ratio 028 046 029 026

Youngrsquos Modulus (GPa) 243 303 246 206

Cut-off Area Shrinking () 803 803 726 601

Elongation () 566 65 602 647

Table 3-6 Mechanical Properties of SUM 23 Nickel

59

Stress-Strain Diagram

(a)

60

(b)

(c)

(d)

61

Fig 3-15 Stress-Strain Diagrams for (a) 1 Round Bar (b) 2 Round Bar (c) 3 Round Bar and (d)

4 Round Bar

Cut-Off Area

(a)

(b)

62

(c)

(d)

Fig 3-16 Cut-Off Area of (a) 1 Round Bar (b) 2 Round Bar (c) 3 Round Bar and (d) 4 Round

Bar

63

SUM 23 Black Surface Round Bar

Fig 3-17 SUM 23 Black Surface Material

Number 1 2 3

Hardness(HRB) 51 50 51

Yield Stress (MPa) 378 371 369

Tensile Strength (MPa) 467 465 464

Poissonrsquos Ratio 03 016 04

Youngrsquos Modulus (GPa) 215 266 266

Cut-off Area Shrinking () 986 94 848

Elongation () 748 805 761

Table 3-7 Mechanical Properties of SUM 23 Black Surface Material

64

Stress-Strain Diagram

(a)

(b)

65

(c)

Fig 3-18 Stress-Strain Diagrams for (a) 1 Round Bar 2 Round Bar and (c) 3 Round Bar

Cut-Off Surface

(a)

66

(b)

(c)

Fig 3-19 Cut-Off Surface of (a) 1 Round Bar 2 Round Bar and (c) 3 Round Bar

67

342 SUM 43

Fig 3-20 Untreated SUM 43 Untreated Material

Number 1 5

Hardness(HRB) 76 75

Yield Stress (MPa) 572 594

Tensile Strength (MPa) 743 785

Poissonrsquos Ratio 027 029

Youngrsquos Modulus (GPa) 200 202

Cut-off Area Shrinking () 338 2944

Elongation () 857 894

Table 3-8 Mechanical Properties of SUM 43 Untreated

68

Stress-Strain Diagrams

(a)

(b)

Fig 3-21 Stress-Strain Diagrams for SUM 43 (a) 1 Round Bar and (b) 5 Round Bar

69

Cut-Off Area

(a)

(b)

Fig 3-22 Cut-Off Area of SUM 43 (a) 1 Round Bar and (b) 5 Round Bar

70

SUM 43 Nickel Round Bar

Fig 3-23 SUM 43 Nickel Material

Number 4 5

Hardness(HRB) 51 50

Yield Stress (MPa) 1580 1544

Tensile Strength (MPa) 1639 1625

Poissonrsquos Ratio 03 028

Youngrsquos Modulus (GPa) 194 201

Cut-off Area Shrinking () 1697 137

Elongation () 376 265

Table 3-9 Mechanical Properties of SUM 43 Nickel

71

Stress-Strain Diagrams

(a)

(b)

Fig 3-24 Stress-Strain Diagrams for (a) 4 Round Bar and (b) 5 Round Bar

72

Cut-Off Area

(a)

(b)

Fig 3-25 Cut-Off Area of (a) 4 Round Bar and (b) 5 Round Bar

73

SUM 43 Black Surface Material

Fig 3-26 SUM 43 Black Surface Material

Number 3 5

Hardness(HRB) 56 56

Yield Stress (MPa) 1416 1361

Tensile Strength (MPa) 1591 1402

Poissonrsquos Ratio 029 031

Youngrsquos Modulus (GPa) 200 202

Cut-off Area Shrinking () 139 124

Elongation () 24 24

Table 3-10 Mechanical Properties of SUM 43 Black Surface Material

74

Stress-Strain Diagrams

0 2 4 6 8 10 12 14

-200

0

200

400

600

800

1000

1200

1400

1600

1800

應力 (MPa)

應變()

(a)

0 2 4 6 8 10

-200

0

200

400

600

800

1000

1200

1400

1600

應力

(MPa)

位移 ()

(b)

Fig 3-27 Stress-Strain Diagrams for (a) 3 Round Bar and (b) 5 Round Bar

(Note These curves were formulated using Visual Solutions Inc VisSim Software)

75

Cut-Off Area

(a)

(b)

Fig 3-28 Cut-Off Area of (a) 3 Round Bar and (b) 5 Round Bar

76

The force value (N) was retrieved from the Universal Testing Machine

The Poissonrsquos Ratio (ε) is calculated as

ε =

the values for the Poissonrsquos Ratio are in average around 0297

The Youngrsquos Modulus (E) is calculated as

E =

Where

Stress =

Cross-sectional Area =

where D is the Diameter

The value for D was in average around 1258 mm

The values shown by the computer because there is Slippage phenomena between the Clamp and the

specimen will not be taken into consideration for the elongation strain and Youngrsquos modulus and we will

refer to the values that we have meticulously calculated

77

Chapter 4 AR COATING IN DEPTH

41 Experimentrsquos Purpose and Principles

By means of a vacuum chamber and several other instruments we intend to apply Anti-Reflective

Coating using deposition process to a laser diode and in this way reduce its refraction so as to make it

lose less light in the process of amplification and we can control certain wavelengths we want produced

for certain desired applications in our case we are attempting to re-create a Bose-Einstein Condensate

An optimal BEC apparatus is shown in figure 4-1

Fig 4-1 BEC Apparatus

The main point of this experiment is to build a vacuum chamber system attach all the instrumentation

needed (Vacuum pump deposition meter and voltmeter) and use it to apply AR coating to a laser diode

After we have accomplished the AR coating other team will be in charge of designing the BEC apparatus

and use the results of our research

78

42 Experimentrsquos Equipment

421 Vacuum Chamber

For this research we designed a vacuum chamber whose main body is shown in figure 4-2 Its

dimensions are

Width 240 mm

Length 240 mm

Height 200 mm

Outer Diameter 4 in

Inner Diameter 15 in

Fig 4-2 Vacuum Chamber Main Body

The chamber is made up of 6 pass ways pass way A is the connection with the Laser Deposition

Equipment pass way B is the connection with the Turbo Pump and pass way C is for the connection with

the Deposition Source

A

C

B

79

Pass way C is for the deposition source as mentioned above This is a system where a thermal

resistance is heated by passing a high current through it which heats up a filament boat (made of tungsten)

where the material to be evaporated is place We control the temperature as such that the material will

evaporate and the heat will not cause the filament boat to crack

Because P = Isup2 R (where P is power I is current and R is resistance) to avoid the current to flow

where it is not desired we decided that the material for the Thermocouple shown in figure 4-3 should be

Copper ᴓ 63 mm We choose it that way because Copper has very good heat dissipation characteristics

and the resistance value is low It can reduce the value of the current enough to make the thermocouple to

create heat

Fig 4-3 Thermocouple

To the thermocouple we attach the tungsten filament boat We need to take notice of materials to be

used in this design because when using high current the tungsten filament boar will heat up and so the

material must be able to keep up with the heating potential of tungsten and has a low coefficient of heat

dissipation to avoid the tungsten to fail when heating up and therefore not evaporating Considering all

this we decide to use Stainless Steel

Because this clamp will be assembled inside the chamber after many revisions it was determined it

will have the shape shown in figure 4-4

Fig 4-4 Filament Boat Clamp Design

80

For the tungsten filament boat we bought the product from a distributor The dimensions are

Length 100 mm

Width 10 mm

Height 1 mm

Our thermocouple is 15 in but the pass way C is 4 in so we need to attach a Flange that connects

15in to 4in Because these specifications are quite difficult to achieve by Milling we had to use

electrical wire cutting

For the laser clamping system where the laser that is going to be AR coated will be placed will be

connected to pass way A the assembly is shown in figure 4-5 below

Fig 4-5 Cover Assembly

For this design we used an O-ring instead of a gasket so as to save time The design of the assembly

where the laser will be placed is shown in figure 4-6

Fig 4-6 Upper Cover Inner Assembly

D

E

F

81

Point D is the plate in the assembly where the laser diode will be fixed Because of the easy

processing we decide to use Aluminum and it is screwed to the top cover Point E is the connection for

the Quartz crystal resonator and it is designed in the same as point F in this way the results of the quartz

microbalance system will be more accurate in real time Point F is the final resting place for the laser

diode We use a Thor Labs Base with dimensions of ᴓ 9mm and ᴓ 56mm for two different size laser

diodes It just needs to be plugged in for easy installation

From figure 4-6 we know that the system needs signal system connections and because of the

change in temperature inside the chamber this could affect the functioning of the quartz microbalance so

we also need to install water tubes for cooling This is shown in figure 4-7 below

Fig 4-7 Diagram of Upper Cover Connections

In figure 4-8 we show the Feed through connections and their functions

Fig 4-8 Feed through Diagram

82

1 SQM-160 wire 5 Laser Connection 1 (Vin)

2 SQM-160 (G) 6 Laser Connection 2 (G)

3 K-Type-1 7 Laser Connection 3 (PD)

4 K-Type-2 8 Not In Use

The fully assembled chamber is shown in figure 4-9

Fig 4-9 Fully Assembled Chamber

422 Quartz Crystal Microbalance

For measuring the deposition on our target for coating we used the Inficon SQM-160 RateThickness

Monitor It is an easy to use instrument for measuring many types of thin-film coatings as shown in

figure 4-10

(a) Front Panel (b) Back Panel

Fig 4-10 Inficon SQM-160

83

Table 4-1 shows the technical specifications for this equipment

Number of sensors 2 Standard 4 additional optional

Sensor Frequency Range 40 MHz ~ 60 MHz

Reference Frequency Accuracy 002

Thickness Display Resolution 1 Aring

Thickness Resolution 015 Aring (Std) 0037 Aring (Hi Res)

Density of Stored Films 05-9999 gmcc

Tooling 10-399

Z-Factor 010-1000

Final Thickness 0000-9999k Aring

Measurement Period 15 to 2 sec

Simulation Mode Yes

Frequency Mode Yes

Rate Resolution 011 Arings

Dual Crystal Yes

Etch Mode Yes

Crystal Tooling 10-399

Crystal Fail Min Max 40 to 60 MHz 41 to 61 MHz

Power 100-120 200-240~plusmn10 nominal 20W

Operation Environment 0degC ~ 50degC

0 ~ 80 RH non-condensing

0 ~ 2000 meters

Class 1 Equipment

Pollution Degree 2

Rack Dimensions 885mm x 2127mm x 1969mm

Weight 27 kg

Table 4-1 Inficon SQM-160 RateThickness Monitor Specs

84

To the SQM-160 we need to connect an Oscillator We use the Sigma Instruments Remote Oscillator

Ser No 2 268 as shown in figure 4-11

Fig 4-11 Sigma Instruments Remote Oscillator

The connections diagram is shown in figure 4-12

Fig 4-12 SQM-160 Connections Diagram

85

423 Turbo Pump

For our experiments we used the Pfeiffer TCP 015 Electronic Drive Unit shown below in figure 4-13

Table 4-2 shows the technical specifications for this equipment

(a) Front Panel (b) Back Panel

Fig 4-13 Pfeiffer TCP 015 Electronic Drive

Connection Voltage (100V) 90-112

Mains Frequency 5060 Hz

Start-up Current 22 A

Nominal Frequency 1500 Hz

Rotation Speed 10V = 1500Hz plusmn2

Analog Output Current 10 V = 25 A plusmn 5

Rotation Speed Switchpoint 750 Hz

Works Setting 8 min

Permissible Ambient Temperature 0degC ~ 40degC

Dimensions Front Panel 1285mm x 1063mm

Insertion Length 227mm

Weight 27 Kg

Table 4-2 Pfeiffer TCP 015 Electronic Drive Specs

86

The connections diagram is shown in figure 4-14

Fig 4-14Connections Diagram for Pfeiffer TCP 015

To measure the pressure inside the chamber we use the Granville Phillips 375 Convectron Vacuum

Pressure Controller shown in figure 4-15

(a) Front Panel (b) Back Panel

Fig 4-15 Granville Phillips 375 Convectron

87

Its dimensions are shown in figure 4-16

Fig 4-16 Dimensions of Convectron

Table 4-3 shows the technical specifications for this equipment

Table 4-3 Granville Phillips 375 Convectron Vacuum Pressure Controller Specs

88

424 Multimeter

For our experiment we used the Keithley 2000 Digital Multimeter as shown in figure 4-17

(a) Front Panel (b) Back Panel

Fig 4-17 Keithley Model 2000 6-12-Digit Digital Multimeter

Its technical specifications are shown in table 4-4

Table 4-4 Keithley Model 2000 6-12-Digit Digital Multimeter Specs

89

43 Experiment Procedure

1 Connecting together the equipment and the chamber

(1) We first connect the resonator to the thickness monitor and connect the other side to the

chamber

(2) We now connect the flexible tubes to the turbo pump on one side and to the chamber on the

other

(3) We need to check that tubes are tightly connected to avoid any leaks in the vacuum pumping

process which will not allow us to get to our goal of Torr As shown in figure 4-18

(4) Connect the convectron to the system as shown in figure 4-19

Fig 4-18 checking for leaks using alcohol

Fig 4-19 Convectron attached to System

90

(5) Attach the clamps of the Multimeter to the bottom of the chamber as shown in figure 4-20

(6) Place the Quartz crystal in place

(7) Close tight vacuum chamber

(8) Connect all electrical appliances to power source

Fig 4-20 Multimeter Connections

2 Starting up the System

(1) We turn on all the devices as such Check all systems are ready to function Reset all values

that might be left over from previous tests

(2) Start the thickness monitor and set all values for this experiment In our case we got to testing

the system but not actual coating So we used the simulation mode of the thickness monitor as

shown in figure 4-21

Fig 4-21 Simulation Mode

91

(3) Start the turbo pump Make sure the lid on the vacuum chamber is tightly closed

(4) Start convectron and record initial pressure

(5) Start Multimeter and record initial current

3 Coating Process

(1) If we have the deposition material inside the filament boat the power source for the high

current must be started as well

(2) Record all initial values for thickness current pressure

(3) For an ideal experiment we need a thickness of around 101 nm a pressure of Torr and

a current of 300 A

44 Results

From previous experiments we have shown that we can turn a LED into a laser by means of AR

Coating In figure 4-22 shown below we can compare the actual results of a Diode before and after AR

coating From the blue line we can see that when the diode is at a current of 15mA its light will change

from LED to laser and if we look at the red line its critical current is around 30 to 35 mA

Fig 4-22 AR Coating Comparison for Laser Diodes

This means that the light emitted is not as strong as if the diode had been coated because inside the

chamber there must be some excitation first so the reflectivity of both sides inside the diode must be high

So because of the coating in one of the sides we have opened a door and let the light come out so the

critical current is risen as such and will be higher value than that of before the coating

92

In the following figures we can see the difference between before and after coating in a material The

thickness is around 1016 nm for this material

Fig 4-23 Before Coating

Fig 4-24 After Coating

93

Chapter 5 CONCLUSIONS AND RECOMMENDATIONS

51 Conclusions

For the first part of this independent study taking into consideration the data that came out of our

research and that sent by the provider we can say

1 SUM 23 after heat treatment will unexpectedly develop cracking in the middle of the tensile

testing process and suddenly break

2 Itrsquos possible that in the process of heat treatment to the SUM 23 material the treatment was not

uniform and this will create a pre-loaded moment force on one side that pushes on the other side

of the specimen resulting in material deformation

3 In the process of attaching the strain gauges to the materials it is very easy to make errors due to

poor adhesion or sudden removal in the tensile testing process

For our second part of the independent study the following can be made

1 At the beginning of this independent study we had no idea what Bose-Einstein Condensate was

or what was its purpose After much literature we finally comprehended the basic principles to

put into practice for our research

2 Our systemrsquos basic working principles and equipmentrsquos complexity are a little difficult to grasp

but hopefully we were able to understand enough of it

3 Theoretically from relation between the power and current we can know the advantages and

disadvantages of AR Coating

4 We were able to assemble the system and run test on its functions Even though we were able to

do this there is still much more work left to do with this system

52 Recommendations

For the Tensile Testing the following can be said

1 Ask the provider to check on the process of heat treatment on the SUM 23 material and give

them the information we have gathered through our test so they can correct for the mechanical

properties found if any change is needed

2 To avoid the problem of the inaccuracy of the poor adhesion of strain gauges we can attach

multiple strain gauges to the same one specimen so as to correlate data and improve our results

For the AR Coating the following can be said

1 We need to make sure that there are no physical defects on the main body of the chamber so as to

achieve maximum efficiency in the vacuum process If there was then the vacuum will arrive to

certain point and then start to decrease

2 It would be preferable to add some sort of visual aid that will allow the user to check the inside of

the chamber without actually opening it This will help us determine at what times we should

manipulate the current to better evaporate the substrate

94

REFERENCES

[1] A L Window Strain Gauge Technology Elsevier Applied Science London and New York 2nd

Edition 1992

[2] CC Perry and HR Lissner Strain Gauge Primer McGraw-Hill Book Co Inc New York 1955

[3] James W Dally William F Riley McGraw-Hill 1978

[4] University of Colorado Boulder BEC - What is it and where did the idea come from

httpwwwcoloradoeduphysics2000becwhat_is_ithtml

[5] Ultraslow Light amp Bose-Einstein Condensates Two-way Control with Coherent Light amp Atom

Fields Harvard Hau Lab Dr Lene Vestergaard Hau Optics amp Photonics News 16 1995

[6] The Art of Taming Light Ultra-slow and Stopped Light Harvard Hau Lab Dr Lene

Vestergaard Hau Europhysics News 2004

[7] Nonlinear Optics Shocking Superfluids Harvard Hau Lab Dr Lene Vestergaard Hau Nature

Physics 2007

[8] Model P3 Strain Indicator and Recorder Instruction Manual Vishay Micro-Measurements 2005

[9] Granville-Phillips Series 375 Convectron Vacuum Gauge Controller Instruction Manual Brooks

Automation 2008

[10] Effect of Film Thickness on the Validity of the Sauerbrey Equation for Hydrated Polyelectrolyte

Films Vogt Lin Wu White 2004

[11] Quartz Crystal Microbalance Study of DNA Immobilization and Hybridization for DNA Sensor

Development Chang Zhao 2008

[12] Installation of Strain Gages with SR-4 PrecoatAdhesive Vishay Micro-Measurements 2005

[13] Strain Gauge Measurement ndash A Tutorial National Instruments 1998

[14] Correlation between Vickers Hardness Number and Yield Stress of Cold-Formed Products

Yavuz Tekkaya

[15] httpsenwikipediaorg

Page 56: PC Hinge Materials Testing and AR Laser Diode Coating

56

Stress-Strain Diagram

(a)

(b)

57

Fig 3-12 Stress-Strain Diagrams for (a) 7 Round Bar and (b) 10 Round Bar

Cut-Off Area

(a)

(b)

Fig 3-13 Cut-Off Area of (a) 7 Round Bar and (b) 10 Round Bar

58

SUM 23 Nickel Round Bar

Fig 3-14 SUM 23 Nickel Material

Number 1 2 3 4

Hardness(HRB) 48 50 49 48

Yield Stress (MPa) 370 370 380 400

Tensile Strength (MPa) 455 451 450 450

Poissonrsquos Ratio 028 046 029 026

Youngrsquos Modulus (GPa) 243 303 246 206

Cut-off Area Shrinking () 803 803 726 601

Elongation () 566 65 602 647

Table 3-6 Mechanical Properties of SUM 23 Nickel

59

Stress-Strain Diagram

(a)

60

(b)

(c)

(d)

61

Fig 3-15 Stress-Strain Diagrams for (a) 1 Round Bar (b) 2 Round Bar (c) 3 Round Bar and (d)

4 Round Bar

Cut-Off Area

(a)

(b)

62

(c)

(d)

Fig 3-16 Cut-Off Area of (a) 1 Round Bar (b) 2 Round Bar (c) 3 Round Bar and (d) 4 Round

Bar

63

SUM 23 Black Surface Round Bar

Fig 3-17 SUM 23 Black Surface Material

Number 1 2 3

Hardness(HRB) 51 50 51

Yield Stress (MPa) 378 371 369

Tensile Strength (MPa) 467 465 464

Poissonrsquos Ratio 03 016 04

Youngrsquos Modulus (GPa) 215 266 266

Cut-off Area Shrinking () 986 94 848

Elongation () 748 805 761

Table 3-7 Mechanical Properties of SUM 23 Black Surface Material

64

Stress-Strain Diagram

(a)

(b)

65

(c)

Fig 3-18 Stress-Strain Diagrams for (a) 1 Round Bar 2 Round Bar and (c) 3 Round Bar

Cut-Off Surface

(a)

66

(b)

(c)

Fig 3-19 Cut-Off Surface of (a) 1 Round Bar 2 Round Bar and (c) 3 Round Bar

67

342 SUM 43

Fig 3-20 Untreated SUM 43 Untreated Material

Number 1 5

Hardness(HRB) 76 75

Yield Stress (MPa) 572 594

Tensile Strength (MPa) 743 785

Poissonrsquos Ratio 027 029

Youngrsquos Modulus (GPa) 200 202

Cut-off Area Shrinking () 338 2944

Elongation () 857 894

Table 3-8 Mechanical Properties of SUM 43 Untreated

68

Stress-Strain Diagrams

(a)

(b)

Fig 3-21 Stress-Strain Diagrams for SUM 43 (a) 1 Round Bar and (b) 5 Round Bar

69

Cut-Off Area

(a)

(b)

Fig 3-22 Cut-Off Area of SUM 43 (a) 1 Round Bar and (b) 5 Round Bar

70

SUM 43 Nickel Round Bar

Fig 3-23 SUM 43 Nickel Material

Number 4 5

Hardness(HRB) 51 50

Yield Stress (MPa) 1580 1544

Tensile Strength (MPa) 1639 1625

Poissonrsquos Ratio 03 028

Youngrsquos Modulus (GPa) 194 201

Cut-off Area Shrinking () 1697 137

Elongation () 376 265

Table 3-9 Mechanical Properties of SUM 43 Nickel

71

Stress-Strain Diagrams

(a)

(b)

Fig 3-24 Stress-Strain Diagrams for (a) 4 Round Bar and (b) 5 Round Bar

72

Cut-Off Area

(a)

(b)

Fig 3-25 Cut-Off Area of (a) 4 Round Bar and (b) 5 Round Bar

73

SUM 43 Black Surface Material

Fig 3-26 SUM 43 Black Surface Material

Number 3 5

Hardness(HRB) 56 56

Yield Stress (MPa) 1416 1361

Tensile Strength (MPa) 1591 1402

Poissonrsquos Ratio 029 031

Youngrsquos Modulus (GPa) 200 202

Cut-off Area Shrinking () 139 124

Elongation () 24 24

Table 3-10 Mechanical Properties of SUM 43 Black Surface Material

74

Stress-Strain Diagrams

0 2 4 6 8 10 12 14

-200

0

200

400

600

800

1000

1200

1400

1600

1800

應力 (MPa)

應變()

(a)

0 2 4 6 8 10

-200

0

200

400

600

800

1000

1200

1400

1600

應力

(MPa)

位移 ()

(b)

Fig 3-27 Stress-Strain Diagrams for (a) 3 Round Bar and (b) 5 Round Bar

(Note These curves were formulated using Visual Solutions Inc VisSim Software)

75

Cut-Off Area

(a)

(b)

Fig 3-28 Cut-Off Area of (a) 3 Round Bar and (b) 5 Round Bar

76

The force value (N) was retrieved from the Universal Testing Machine

The Poissonrsquos Ratio (ε) is calculated as

ε =

the values for the Poissonrsquos Ratio are in average around 0297

The Youngrsquos Modulus (E) is calculated as

E =

Where

Stress =

Cross-sectional Area =

where D is the Diameter

The value for D was in average around 1258 mm

The values shown by the computer because there is Slippage phenomena between the Clamp and the

specimen will not be taken into consideration for the elongation strain and Youngrsquos modulus and we will

refer to the values that we have meticulously calculated

77

Chapter 4 AR COATING IN DEPTH

41 Experimentrsquos Purpose and Principles

By means of a vacuum chamber and several other instruments we intend to apply Anti-Reflective

Coating using deposition process to a laser diode and in this way reduce its refraction so as to make it

lose less light in the process of amplification and we can control certain wavelengths we want produced

for certain desired applications in our case we are attempting to re-create a Bose-Einstein Condensate

An optimal BEC apparatus is shown in figure 4-1

Fig 4-1 BEC Apparatus

The main point of this experiment is to build a vacuum chamber system attach all the instrumentation

needed (Vacuum pump deposition meter and voltmeter) and use it to apply AR coating to a laser diode

After we have accomplished the AR coating other team will be in charge of designing the BEC apparatus

and use the results of our research

78

42 Experimentrsquos Equipment

421 Vacuum Chamber

For this research we designed a vacuum chamber whose main body is shown in figure 4-2 Its

dimensions are

Width 240 mm

Length 240 mm

Height 200 mm

Outer Diameter 4 in

Inner Diameter 15 in

Fig 4-2 Vacuum Chamber Main Body

The chamber is made up of 6 pass ways pass way A is the connection with the Laser Deposition

Equipment pass way B is the connection with the Turbo Pump and pass way C is for the connection with

the Deposition Source

A

C

B

79

Pass way C is for the deposition source as mentioned above This is a system where a thermal

resistance is heated by passing a high current through it which heats up a filament boat (made of tungsten)

where the material to be evaporated is place We control the temperature as such that the material will

evaporate and the heat will not cause the filament boat to crack

Because P = Isup2 R (where P is power I is current and R is resistance) to avoid the current to flow

where it is not desired we decided that the material for the Thermocouple shown in figure 4-3 should be

Copper ᴓ 63 mm We choose it that way because Copper has very good heat dissipation characteristics

and the resistance value is low It can reduce the value of the current enough to make the thermocouple to

create heat

Fig 4-3 Thermocouple

To the thermocouple we attach the tungsten filament boat We need to take notice of materials to be

used in this design because when using high current the tungsten filament boar will heat up and so the

material must be able to keep up with the heating potential of tungsten and has a low coefficient of heat

dissipation to avoid the tungsten to fail when heating up and therefore not evaporating Considering all

this we decide to use Stainless Steel

Because this clamp will be assembled inside the chamber after many revisions it was determined it

will have the shape shown in figure 4-4

Fig 4-4 Filament Boat Clamp Design

80

For the tungsten filament boat we bought the product from a distributor The dimensions are

Length 100 mm

Width 10 mm

Height 1 mm

Our thermocouple is 15 in but the pass way C is 4 in so we need to attach a Flange that connects

15in to 4in Because these specifications are quite difficult to achieve by Milling we had to use

electrical wire cutting

For the laser clamping system where the laser that is going to be AR coated will be placed will be

connected to pass way A the assembly is shown in figure 4-5 below

Fig 4-5 Cover Assembly

For this design we used an O-ring instead of a gasket so as to save time The design of the assembly

where the laser will be placed is shown in figure 4-6

Fig 4-6 Upper Cover Inner Assembly

D

E

F

81

Point D is the plate in the assembly where the laser diode will be fixed Because of the easy

processing we decide to use Aluminum and it is screwed to the top cover Point E is the connection for

the Quartz crystal resonator and it is designed in the same as point F in this way the results of the quartz

microbalance system will be more accurate in real time Point F is the final resting place for the laser

diode We use a Thor Labs Base with dimensions of ᴓ 9mm and ᴓ 56mm for two different size laser

diodes It just needs to be plugged in for easy installation

From figure 4-6 we know that the system needs signal system connections and because of the

change in temperature inside the chamber this could affect the functioning of the quartz microbalance so

we also need to install water tubes for cooling This is shown in figure 4-7 below

Fig 4-7 Diagram of Upper Cover Connections

In figure 4-8 we show the Feed through connections and their functions

Fig 4-8 Feed through Diagram

82

1 SQM-160 wire 5 Laser Connection 1 (Vin)

2 SQM-160 (G) 6 Laser Connection 2 (G)

3 K-Type-1 7 Laser Connection 3 (PD)

4 K-Type-2 8 Not In Use

The fully assembled chamber is shown in figure 4-9

Fig 4-9 Fully Assembled Chamber

422 Quartz Crystal Microbalance

For measuring the deposition on our target for coating we used the Inficon SQM-160 RateThickness

Monitor It is an easy to use instrument for measuring many types of thin-film coatings as shown in

figure 4-10

(a) Front Panel (b) Back Panel

Fig 4-10 Inficon SQM-160

83

Table 4-1 shows the technical specifications for this equipment

Number of sensors 2 Standard 4 additional optional

Sensor Frequency Range 40 MHz ~ 60 MHz

Reference Frequency Accuracy 002

Thickness Display Resolution 1 Aring

Thickness Resolution 015 Aring (Std) 0037 Aring (Hi Res)

Density of Stored Films 05-9999 gmcc

Tooling 10-399

Z-Factor 010-1000

Final Thickness 0000-9999k Aring

Measurement Period 15 to 2 sec

Simulation Mode Yes

Frequency Mode Yes

Rate Resolution 011 Arings

Dual Crystal Yes

Etch Mode Yes

Crystal Tooling 10-399

Crystal Fail Min Max 40 to 60 MHz 41 to 61 MHz

Power 100-120 200-240~plusmn10 nominal 20W

Operation Environment 0degC ~ 50degC

0 ~ 80 RH non-condensing

0 ~ 2000 meters

Class 1 Equipment

Pollution Degree 2

Rack Dimensions 885mm x 2127mm x 1969mm

Weight 27 kg

Table 4-1 Inficon SQM-160 RateThickness Monitor Specs

84

To the SQM-160 we need to connect an Oscillator We use the Sigma Instruments Remote Oscillator

Ser No 2 268 as shown in figure 4-11

Fig 4-11 Sigma Instruments Remote Oscillator

The connections diagram is shown in figure 4-12

Fig 4-12 SQM-160 Connections Diagram

85

423 Turbo Pump

For our experiments we used the Pfeiffer TCP 015 Electronic Drive Unit shown below in figure 4-13

Table 4-2 shows the technical specifications for this equipment

(a) Front Panel (b) Back Panel

Fig 4-13 Pfeiffer TCP 015 Electronic Drive

Connection Voltage (100V) 90-112

Mains Frequency 5060 Hz

Start-up Current 22 A

Nominal Frequency 1500 Hz

Rotation Speed 10V = 1500Hz plusmn2

Analog Output Current 10 V = 25 A plusmn 5

Rotation Speed Switchpoint 750 Hz

Works Setting 8 min

Permissible Ambient Temperature 0degC ~ 40degC

Dimensions Front Panel 1285mm x 1063mm

Insertion Length 227mm

Weight 27 Kg

Table 4-2 Pfeiffer TCP 015 Electronic Drive Specs

86

The connections diagram is shown in figure 4-14

Fig 4-14Connections Diagram for Pfeiffer TCP 015

To measure the pressure inside the chamber we use the Granville Phillips 375 Convectron Vacuum

Pressure Controller shown in figure 4-15

(a) Front Panel (b) Back Panel

Fig 4-15 Granville Phillips 375 Convectron

87

Its dimensions are shown in figure 4-16

Fig 4-16 Dimensions of Convectron

Table 4-3 shows the technical specifications for this equipment

Table 4-3 Granville Phillips 375 Convectron Vacuum Pressure Controller Specs

88

424 Multimeter

For our experiment we used the Keithley 2000 Digital Multimeter as shown in figure 4-17

(a) Front Panel (b) Back Panel

Fig 4-17 Keithley Model 2000 6-12-Digit Digital Multimeter

Its technical specifications are shown in table 4-4

Table 4-4 Keithley Model 2000 6-12-Digit Digital Multimeter Specs

89

43 Experiment Procedure

1 Connecting together the equipment and the chamber

(1) We first connect the resonator to the thickness monitor and connect the other side to the

chamber

(2) We now connect the flexible tubes to the turbo pump on one side and to the chamber on the

other

(3) We need to check that tubes are tightly connected to avoid any leaks in the vacuum pumping

process which will not allow us to get to our goal of Torr As shown in figure 4-18

(4) Connect the convectron to the system as shown in figure 4-19

Fig 4-18 checking for leaks using alcohol

Fig 4-19 Convectron attached to System

90

(5) Attach the clamps of the Multimeter to the bottom of the chamber as shown in figure 4-20

(6) Place the Quartz crystal in place

(7) Close tight vacuum chamber

(8) Connect all electrical appliances to power source

Fig 4-20 Multimeter Connections

2 Starting up the System

(1) We turn on all the devices as such Check all systems are ready to function Reset all values

that might be left over from previous tests

(2) Start the thickness monitor and set all values for this experiment In our case we got to testing

the system but not actual coating So we used the simulation mode of the thickness monitor as

shown in figure 4-21

Fig 4-21 Simulation Mode

91

(3) Start the turbo pump Make sure the lid on the vacuum chamber is tightly closed

(4) Start convectron and record initial pressure

(5) Start Multimeter and record initial current

3 Coating Process

(1) If we have the deposition material inside the filament boat the power source for the high

current must be started as well

(2) Record all initial values for thickness current pressure

(3) For an ideal experiment we need a thickness of around 101 nm a pressure of Torr and

a current of 300 A

44 Results

From previous experiments we have shown that we can turn a LED into a laser by means of AR

Coating In figure 4-22 shown below we can compare the actual results of a Diode before and after AR

coating From the blue line we can see that when the diode is at a current of 15mA its light will change

from LED to laser and if we look at the red line its critical current is around 30 to 35 mA

Fig 4-22 AR Coating Comparison for Laser Diodes

This means that the light emitted is not as strong as if the diode had been coated because inside the

chamber there must be some excitation first so the reflectivity of both sides inside the diode must be high

So because of the coating in one of the sides we have opened a door and let the light come out so the

critical current is risen as such and will be higher value than that of before the coating

92

In the following figures we can see the difference between before and after coating in a material The

thickness is around 1016 nm for this material

Fig 4-23 Before Coating

Fig 4-24 After Coating

93

Chapter 5 CONCLUSIONS AND RECOMMENDATIONS

51 Conclusions

For the first part of this independent study taking into consideration the data that came out of our

research and that sent by the provider we can say

1 SUM 23 after heat treatment will unexpectedly develop cracking in the middle of the tensile

testing process and suddenly break

2 Itrsquos possible that in the process of heat treatment to the SUM 23 material the treatment was not

uniform and this will create a pre-loaded moment force on one side that pushes on the other side

of the specimen resulting in material deformation

3 In the process of attaching the strain gauges to the materials it is very easy to make errors due to

poor adhesion or sudden removal in the tensile testing process

For our second part of the independent study the following can be made

1 At the beginning of this independent study we had no idea what Bose-Einstein Condensate was

or what was its purpose After much literature we finally comprehended the basic principles to

put into practice for our research

2 Our systemrsquos basic working principles and equipmentrsquos complexity are a little difficult to grasp

but hopefully we were able to understand enough of it

3 Theoretically from relation between the power and current we can know the advantages and

disadvantages of AR Coating

4 We were able to assemble the system and run test on its functions Even though we were able to

do this there is still much more work left to do with this system

52 Recommendations

For the Tensile Testing the following can be said

1 Ask the provider to check on the process of heat treatment on the SUM 23 material and give

them the information we have gathered through our test so they can correct for the mechanical

properties found if any change is needed

2 To avoid the problem of the inaccuracy of the poor adhesion of strain gauges we can attach

multiple strain gauges to the same one specimen so as to correlate data and improve our results

For the AR Coating the following can be said

1 We need to make sure that there are no physical defects on the main body of the chamber so as to

achieve maximum efficiency in the vacuum process If there was then the vacuum will arrive to

certain point and then start to decrease

2 It would be preferable to add some sort of visual aid that will allow the user to check the inside of

the chamber without actually opening it This will help us determine at what times we should

manipulate the current to better evaporate the substrate

94

REFERENCES

[1] A L Window Strain Gauge Technology Elsevier Applied Science London and New York 2nd

Edition 1992

[2] CC Perry and HR Lissner Strain Gauge Primer McGraw-Hill Book Co Inc New York 1955

[3] James W Dally William F Riley McGraw-Hill 1978

[4] University of Colorado Boulder BEC - What is it and where did the idea come from

httpwwwcoloradoeduphysics2000becwhat_is_ithtml

[5] Ultraslow Light amp Bose-Einstein Condensates Two-way Control with Coherent Light amp Atom

Fields Harvard Hau Lab Dr Lene Vestergaard Hau Optics amp Photonics News 16 1995

[6] The Art of Taming Light Ultra-slow and Stopped Light Harvard Hau Lab Dr Lene

Vestergaard Hau Europhysics News 2004

[7] Nonlinear Optics Shocking Superfluids Harvard Hau Lab Dr Lene Vestergaard Hau Nature

Physics 2007

[8] Model P3 Strain Indicator and Recorder Instruction Manual Vishay Micro-Measurements 2005

[9] Granville-Phillips Series 375 Convectron Vacuum Gauge Controller Instruction Manual Brooks

Automation 2008

[10] Effect of Film Thickness on the Validity of the Sauerbrey Equation for Hydrated Polyelectrolyte

Films Vogt Lin Wu White 2004

[11] Quartz Crystal Microbalance Study of DNA Immobilization and Hybridization for DNA Sensor

Development Chang Zhao 2008

[12] Installation of Strain Gages with SR-4 PrecoatAdhesive Vishay Micro-Measurements 2005

[13] Strain Gauge Measurement ndash A Tutorial National Instruments 1998

[14] Correlation between Vickers Hardness Number and Yield Stress of Cold-Formed Products

Yavuz Tekkaya

[15] httpsenwikipediaorg

Page 57: PC Hinge Materials Testing and AR Laser Diode Coating

57

Fig 3-12 Stress-Strain Diagrams for (a) 7 Round Bar and (b) 10 Round Bar

Cut-Off Area

(a)

(b)

Fig 3-13 Cut-Off Area of (a) 7 Round Bar and (b) 10 Round Bar

58

SUM 23 Nickel Round Bar

Fig 3-14 SUM 23 Nickel Material

Number 1 2 3 4

Hardness(HRB) 48 50 49 48

Yield Stress (MPa) 370 370 380 400

Tensile Strength (MPa) 455 451 450 450

Poissonrsquos Ratio 028 046 029 026

Youngrsquos Modulus (GPa) 243 303 246 206

Cut-off Area Shrinking () 803 803 726 601

Elongation () 566 65 602 647

Table 3-6 Mechanical Properties of SUM 23 Nickel

59

Stress-Strain Diagram

(a)

60

(b)

(c)

(d)

61

Fig 3-15 Stress-Strain Diagrams for (a) 1 Round Bar (b) 2 Round Bar (c) 3 Round Bar and (d)

4 Round Bar

Cut-Off Area

(a)

(b)

62

(c)

(d)

Fig 3-16 Cut-Off Area of (a) 1 Round Bar (b) 2 Round Bar (c) 3 Round Bar and (d) 4 Round

Bar

63

SUM 23 Black Surface Round Bar

Fig 3-17 SUM 23 Black Surface Material

Number 1 2 3

Hardness(HRB) 51 50 51

Yield Stress (MPa) 378 371 369

Tensile Strength (MPa) 467 465 464

Poissonrsquos Ratio 03 016 04

Youngrsquos Modulus (GPa) 215 266 266

Cut-off Area Shrinking () 986 94 848

Elongation () 748 805 761

Table 3-7 Mechanical Properties of SUM 23 Black Surface Material

64

Stress-Strain Diagram

(a)

(b)

65

(c)

Fig 3-18 Stress-Strain Diagrams for (a) 1 Round Bar 2 Round Bar and (c) 3 Round Bar

Cut-Off Surface

(a)

66

(b)

(c)

Fig 3-19 Cut-Off Surface of (a) 1 Round Bar 2 Round Bar and (c) 3 Round Bar

67

342 SUM 43

Fig 3-20 Untreated SUM 43 Untreated Material

Number 1 5

Hardness(HRB) 76 75

Yield Stress (MPa) 572 594

Tensile Strength (MPa) 743 785

Poissonrsquos Ratio 027 029

Youngrsquos Modulus (GPa) 200 202

Cut-off Area Shrinking () 338 2944

Elongation () 857 894

Table 3-8 Mechanical Properties of SUM 43 Untreated

68

Stress-Strain Diagrams

(a)

(b)

Fig 3-21 Stress-Strain Diagrams for SUM 43 (a) 1 Round Bar and (b) 5 Round Bar

69

Cut-Off Area

(a)

(b)

Fig 3-22 Cut-Off Area of SUM 43 (a) 1 Round Bar and (b) 5 Round Bar

70

SUM 43 Nickel Round Bar

Fig 3-23 SUM 43 Nickel Material

Number 4 5

Hardness(HRB) 51 50

Yield Stress (MPa) 1580 1544

Tensile Strength (MPa) 1639 1625

Poissonrsquos Ratio 03 028

Youngrsquos Modulus (GPa) 194 201

Cut-off Area Shrinking () 1697 137

Elongation () 376 265

Table 3-9 Mechanical Properties of SUM 43 Nickel

71

Stress-Strain Diagrams

(a)

(b)

Fig 3-24 Stress-Strain Diagrams for (a) 4 Round Bar and (b) 5 Round Bar

72

Cut-Off Area

(a)

(b)

Fig 3-25 Cut-Off Area of (a) 4 Round Bar and (b) 5 Round Bar

73

SUM 43 Black Surface Material

Fig 3-26 SUM 43 Black Surface Material

Number 3 5

Hardness(HRB) 56 56

Yield Stress (MPa) 1416 1361

Tensile Strength (MPa) 1591 1402

Poissonrsquos Ratio 029 031

Youngrsquos Modulus (GPa) 200 202

Cut-off Area Shrinking () 139 124

Elongation () 24 24

Table 3-10 Mechanical Properties of SUM 43 Black Surface Material

74

Stress-Strain Diagrams

0 2 4 6 8 10 12 14

-200

0

200

400

600

800

1000

1200

1400

1600

1800

應力 (MPa)

應變()

(a)

0 2 4 6 8 10

-200

0

200

400

600

800

1000

1200

1400

1600

應力

(MPa)

位移 ()

(b)

Fig 3-27 Stress-Strain Diagrams for (a) 3 Round Bar and (b) 5 Round Bar

(Note These curves were formulated using Visual Solutions Inc VisSim Software)

75

Cut-Off Area

(a)

(b)

Fig 3-28 Cut-Off Area of (a) 3 Round Bar and (b) 5 Round Bar

76

The force value (N) was retrieved from the Universal Testing Machine

The Poissonrsquos Ratio (ε) is calculated as

ε =

the values for the Poissonrsquos Ratio are in average around 0297

The Youngrsquos Modulus (E) is calculated as

E =

Where

Stress =

Cross-sectional Area =

where D is the Diameter

The value for D was in average around 1258 mm

The values shown by the computer because there is Slippage phenomena between the Clamp and the

specimen will not be taken into consideration for the elongation strain and Youngrsquos modulus and we will

refer to the values that we have meticulously calculated

77

Chapter 4 AR COATING IN DEPTH

41 Experimentrsquos Purpose and Principles

By means of a vacuum chamber and several other instruments we intend to apply Anti-Reflective

Coating using deposition process to a laser diode and in this way reduce its refraction so as to make it

lose less light in the process of amplification and we can control certain wavelengths we want produced

for certain desired applications in our case we are attempting to re-create a Bose-Einstein Condensate

An optimal BEC apparatus is shown in figure 4-1

Fig 4-1 BEC Apparatus

The main point of this experiment is to build a vacuum chamber system attach all the instrumentation

needed (Vacuum pump deposition meter and voltmeter) and use it to apply AR coating to a laser diode

After we have accomplished the AR coating other team will be in charge of designing the BEC apparatus

and use the results of our research

78

42 Experimentrsquos Equipment

421 Vacuum Chamber

For this research we designed a vacuum chamber whose main body is shown in figure 4-2 Its

dimensions are

Width 240 mm

Length 240 mm

Height 200 mm

Outer Diameter 4 in

Inner Diameter 15 in

Fig 4-2 Vacuum Chamber Main Body

The chamber is made up of 6 pass ways pass way A is the connection with the Laser Deposition

Equipment pass way B is the connection with the Turbo Pump and pass way C is for the connection with

the Deposition Source

A

C

B

79

Pass way C is for the deposition source as mentioned above This is a system where a thermal

resistance is heated by passing a high current through it which heats up a filament boat (made of tungsten)

where the material to be evaporated is place We control the temperature as such that the material will

evaporate and the heat will not cause the filament boat to crack

Because P = Isup2 R (where P is power I is current and R is resistance) to avoid the current to flow

where it is not desired we decided that the material for the Thermocouple shown in figure 4-3 should be

Copper ᴓ 63 mm We choose it that way because Copper has very good heat dissipation characteristics

and the resistance value is low It can reduce the value of the current enough to make the thermocouple to

create heat

Fig 4-3 Thermocouple

To the thermocouple we attach the tungsten filament boat We need to take notice of materials to be

used in this design because when using high current the tungsten filament boar will heat up and so the

material must be able to keep up with the heating potential of tungsten and has a low coefficient of heat

dissipation to avoid the tungsten to fail when heating up and therefore not evaporating Considering all

this we decide to use Stainless Steel

Because this clamp will be assembled inside the chamber after many revisions it was determined it

will have the shape shown in figure 4-4

Fig 4-4 Filament Boat Clamp Design

80

For the tungsten filament boat we bought the product from a distributor The dimensions are

Length 100 mm

Width 10 mm

Height 1 mm

Our thermocouple is 15 in but the pass way C is 4 in so we need to attach a Flange that connects

15in to 4in Because these specifications are quite difficult to achieve by Milling we had to use

electrical wire cutting

For the laser clamping system where the laser that is going to be AR coated will be placed will be

connected to pass way A the assembly is shown in figure 4-5 below

Fig 4-5 Cover Assembly

For this design we used an O-ring instead of a gasket so as to save time The design of the assembly

where the laser will be placed is shown in figure 4-6

Fig 4-6 Upper Cover Inner Assembly

D

E

F

81

Point D is the plate in the assembly where the laser diode will be fixed Because of the easy

processing we decide to use Aluminum and it is screwed to the top cover Point E is the connection for

the Quartz crystal resonator and it is designed in the same as point F in this way the results of the quartz

microbalance system will be more accurate in real time Point F is the final resting place for the laser

diode We use a Thor Labs Base with dimensions of ᴓ 9mm and ᴓ 56mm for two different size laser

diodes It just needs to be plugged in for easy installation

From figure 4-6 we know that the system needs signal system connections and because of the

change in temperature inside the chamber this could affect the functioning of the quartz microbalance so

we also need to install water tubes for cooling This is shown in figure 4-7 below

Fig 4-7 Diagram of Upper Cover Connections

In figure 4-8 we show the Feed through connections and their functions

Fig 4-8 Feed through Diagram

82

1 SQM-160 wire 5 Laser Connection 1 (Vin)

2 SQM-160 (G) 6 Laser Connection 2 (G)

3 K-Type-1 7 Laser Connection 3 (PD)

4 K-Type-2 8 Not In Use

The fully assembled chamber is shown in figure 4-9

Fig 4-9 Fully Assembled Chamber

422 Quartz Crystal Microbalance

For measuring the deposition on our target for coating we used the Inficon SQM-160 RateThickness

Monitor It is an easy to use instrument for measuring many types of thin-film coatings as shown in

figure 4-10

(a) Front Panel (b) Back Panel

Fig 4-10 Inficon SQM-160

83

Table 4-1 shows the technical specifications for this equipment

Number of sensors 2 Standard 4 additional optional

Sensor Frequency Range 40 MHz ~ 60 MHz

Reference Frequency Accuracy 002

Thickness Display Resolution 1 Aring

Thickness Resolution 015 Aring (Std) 0037 Aring (Hi Res)

Density of Stored Films 05-9999 gmcc

Tooling 10-399

Z-Factor 010-1000

Final Thickness 0000-9999k Aring

Measurement Period 15 to 2 sec

Simulation Mode Yes

Frequency Mode Yes

Rate Resolution 011 Arings

Dual Crystal Yes

Etch Mode Yes

Crystal Tooling 10-399

Crystal Fail Min Max 40 to 60 MHz 41 to 61 MHz

Power 100-120 200-240~plusmn10 nominal 20W

Operation Environment 0degC ~ 50degC

0 ~ 80 RH non-condensing

0 ~ 2000 meters

Class 1 Equipment

Pollution Degree 2

Rack Dimensions 885mm x 2127mm x 1969mm

Weight 27 kg

Table 4-1 Inficon SQM-160 RateThickness Monitor Specs

84

To the SQM-160 we need to connect an Oscillator We use the Sigma Instruments Remote Oscillator

Ser No 2 268 as shown in figure 4-11

Fig 4-11 Sigma Instruments Remote Oscillator

The connections diagram is shown in figure 4-12

Fig 4-12 SQM-160 Connections Diagram

85

423 Turbo Pump

For our experiments we used the Pfeiffer TCP 015 Electronic Drive Unit shown below in figure 4-13

Table 4-2 shows the technical specifications for this equipment

(a) Front Panel (b) Back Panel

Fig 4-13 Pfeiffer TCP 015 Electronic Drive

Connection Voltage (100V) 90-112

Mains Frequency 5060 Hz

Start-up Current 22 A

Nominal Frequency 1500 Hz

Rotation Speed 10V = 1500Hz plusmn2

Analog Output Current 10 V = 25 A plusmn 5

Rotation Speed Switchpoint 750 Hz

Works Setting 8 min

Permissible Ambient Temperature 0degC ~ 40degC

Dimensions Front Panel 1285mm x 1063mm

Insertion Length 227mm

Weight 27 Kg

Table 4-2 Pfeiffer TCP 015 Electronic Drive Specs

86

The connections diagram is shown in figure 4-14

Fig 4-14Connections Diagram for Pfeiffer TCP 015

To measure the pressure inside the chamber we use the Granville Phillips 375 Convectron Vacuum

Pressure Controller shown in figure 4-15

(a) Front Panel (b) Back Panel

Fig 4-15 Granville Phillips 375 Convectron

87

Its dimensions are shown in figure 4-16

Fig 4-16 Dimensions of Convectron

Table 4-3 shows the technical specifications for this equipment

Table 4-3 Granville Phillips 375 Convectron Vacuum Pressure Controller Specs

88

424 Multimeter

For our experiment we used the Keithley 2000 Digital Multimeter as shown in figure 4-17

(a) Front Panel (b) Back Panel

Fig 4-17 Keithley Model 2000 6-12-Digit Digital Multimeter

Its technical specifications are shown in table 4-4

Table 4-4 Keithley Model 2000 6-12-Digit Digital Multimeter Specs

89

43 Experiment Procedure

1 Connecting together the equipment and the chamber

(1) We first connect the resonator to the thickness monitor and connect the other side to the

chamber

(2) We now connect the flexible tubes to the turbo pump on one side and to the chamber on the

other

(3) We need to check that tubes are tightly connected to avoid any leaks in the vacuum pumping

process which will not allow us to get to our goal of Torr As shown in figure 4-18

(4) Connect the convectron to the system as shown in figure 4-19

Fig 4-18 checking for leaks using alcohol

Fig 4-19 Convectron attached to System

90

(5) Attach the clamps of the Multimeter to the bottom of the chamber as shown in figure 4-20

(6) Place the Quartz crystal in place

(7) Close tight vacuum chamber

(8) Connect all electrical appliances to power source

Fig 4-20 Multimeter Connections

2 Starting up the System

(1) We turn on all the devices as such Check all systems are ready to function Reset all values

that might be left over from previous tests

(2) Start the thickness monitor and set all values for this experiment In our case we got to testing

the system but not actual coating So we used the simulation mode of the thickness monitor as

shown in figure 4-21

Fig 4-21 Simulation Mode

91

(3) Start the turbo pump Make sure the lid on the vacuum chamber is tightly closed

(4) Start convectron and record initial pressure

(5) Start Multimeter and record initial current

3 Coating Process

(1) If we have the deposition material inside the filament boat the power source for the high

current must be started as well

(2) Record all initial values for thickness current pressure

(3) For an ideal experiment we need a thickness of around 101 nm a pressure of Torr and

a current of 300 A

44 Results

From previous experiments we have shown that we can turn a LED into a laser by means of AR

Coating In figure 4-22 shown below we can compare the actual results of a Diode before and after AR

coating From the blue line we can see that when the diode is at a current of 15mA its light will change

from LED to laser and if we look at the red line its critical current is around 30 to 35 mA

Fig 4-22 AR Coating Comparison for Laser Diodes

This means that the light emitted is not as strong as if the diode had been coated because inside the

chamber there must be some excitation first so the reflectivity of both sides inside the diode must be high

So because of the coating in one of the sides we have opened a door and let the light come out so the

critical current is risen as such and will be higher value than that of before the coating

92

In the following figures we can see the difference between before and after coating in a material The

thickness is around 1016 nm for this material

Fig 4-23 Before Coating

Fig 4-24 After Coating

93

Chapter 5 CONCLUSIONS AND RECOMMENDATIONS

51 Conclusions

For the first part of this independent study taking into consideration the data that came out of our

research and that sent by the provider we can say

1 SUM 23 after heat treatment will unexpectedly develop cracking in the middle of the tensile

testing process and suddenly break

2 Itrsquos possible that in the process of heat treatment to the SUM 23 material the treatment was not

uniform and this will create a pre-loaded moment force on one side that pushes on the other side

of the specimen resulting in material deformation

3 In the process of attaching the strain gauges to the materials it is very easy to make errors due to

poor adhesion or sudden removal in the tensile testing process

For our second part of the independent study the following can be made

1 At the beginning of this independent study we had no idea what Bose-Einstein Condensate was

or what was its purpose After much literature we finally comprehended the basic principles to

put into practice for our research

2 Our systemrsquos basic working principles and equipmentrsquos complexity are a little difficult to grasp

but hopefully we were able to understand enough of it

3 Theoretically from relation between the power and current we can know the advantages and

disadvantages of AR Coating

4 We were able to assemble the system and run test on its functions Even though we were able to

do this there is still much more work left to do with this system

52 Recommendations

For the Tensile Testing the following can be said

1 Ask the provider to check on the process of heat treatment on the SUM 23 material and give

them the information we have gathered through our test so they can correct for the mechanical

properties found if any change is needed

2 To avoid the problem of the inaccuracy of the poor adhesion of strain gauges we can attach

multiple strain gauges to the same one specimen so as to correlate data and improve our results

For the AR Coating the following can be said

1 We need to make sure that there are no physical defects on the main body of the chamber so as to

achieve maximum efficiency in the vacuum process If there was then the vacuum will arrive to

certain point and then start to decrease

2 It would be preferable to add some sort of visual aid that will allow the user to check the inside of

the chamber without actually opening it This will help us determine at what times we should

manipulate the current to better evaporate the substrate

94

REFERENCES

[1] A L Window Strain Gauge Technology Elsevier Applied Science London and New York 2nd

Edition 1992

[2] CC Perry and HR Lissner Strain Gauge Primer McGraw-Hill Book Co Inc New York 1955

[3] James W Dally William F Riley McGraw-Hill 1978

[4] University of Colorado Boulder BEC - What is it and where did the idea come from

httpwwwcoloradoeduphysics2000becwhat_is_ithtml

[5] Ultraslow Light amp Bose-Einstein Condensates Two-way Control with Coherent Light amp Atom

Fields Harvard Hau Lab Dr Lene Vestergaard Hau Optics amp Photonics News 16 1995

[6] The Art of Taming Light Ultra-slow and Stopped Light Harvard Hau Lab Dr Lene

Vestergaard Hau Europhysics News 2004

[7] Nonlinear Optics Shocking Superfluids Harvard Hau Lab Dr Lene Vestergaard Hau Nature

Physics 2007

[8] Model P3 Strain Indicator and Recorder Instruction Manual Vishay Micro-Measurements 2005

[9] Granville-Phillips Series 375 Convectron Vacuum Gauge Controller Instruction Manual Brooks

Automation 2008

[10] Effect of Film Thickness on the Validity of the Sauerbrey Equation for Hydrated Polyelectrolyte

Films Vogt Lin Wu White 2004

[11] Quartz Crystal Microbalance Study of DNA Immobilization and Hybridization for DNA Sensor

Development Chang Zhao 2008

[12] Installation of Strain Gages with SR-4 PrecoatAdhesive Vishay Micro-Measurements 2005

[13] Strain Gauge Measurement ndash A Tutorial National Instruments 1998

[14] Correlation between Vickers Hardness Number and Yield Stress of Cold-Formed Products

Yavuz Tekkaya

[15] httpsenwikipediaorg

Page 58: PC Hinge Materials Testing and AR Laser Diode Coating

58

SUM 23 Nickel Round Bar

Fig 3-14 SUM 23 Nickel Material

Number 1 2 3 4

Hardness(HRB) 48 50 49 48

Yield Stress (MPa) 370 370 380 400

Tensile Strength (MPa) 455 451 450 450

Poissonrsquos Ratio 028 046 029 026

Youngrsquos Modulus (GPa) 243 303 246 206

Cut-off Area Shrinking () 803 803 726 601

Elongation () 566 65 602 647

Table 3-6 Mechanical Properties of SUM 23 Nickel

59

Stress-Strain Diagram

(a)

60

(b)

(c)

(d)

61

Fig 3-15 Stress-Strain Diagrams for (a) 1 Round Bar (b) 2 Round Bar (c) 3 Round Bar and (d)

4 Round Bar

Cut-Off Area

(a)

(b)

62

(c)

(d)

Fig 3-16 Cut-Off Area of (a) 1 Round Bar (b) 2 Round Bar (c) 3 Round Bar and (d) 4 Round

Bar

63

SUM 23 Black Surface Round Bar

Fig 3-17 SUM 23 Black Surface Material

Number 1 2 3

Hardness(HRB) 51 50 51

Yield Stress (MPa) 378 371 369

Tensile Strength (MPa) 467 465 464

Poissonrsquos Ratio 03 016 04

Youngrsquos Modulus (GPa) 215 266 266

Cut-off Area Shrinking () 986 94 848

Elongation () 748 805 761

Table 3-7 Mechanical Properties of SUM 23 Black Surface Material

64

Stress-Strain Diagram

(a)

(b)

65

(c)

Fig 3-18 Stress-Strain Diagrams for (a) 1 Round Bar 2 Round Bar and (c) 3 Round Bar

Cut-Off Surface

(a)

66

(b)

(c)

Fig 3-19 Cut-Off Surface of (a) 1 Round Bar 2 Round Bar and (c) 3 Round Bar

67

342 SUM 43

Fig 3-20 Untreated SUM 43 Untreated Material

Number 1 5

Hardness(HRB) 76 75

Yield Stress (MPa) 572 594

Tensile Strength (MPa) 743 785

Poissonrsquos Ratio 027 029

Youngrsquos Modulus (GPa) 200 202

Cut-off Area Shrinking () 338 2944

Elongation () 857 894

Table 3-8 Mechanical Properties of SUM 43 Untreated

68

Stress-Strain Diagrams

(a)

(b)

Fig 3-21 Stress-Strain Diagrams for SUM 43 (a) 1 Round Bar and (b) 5 Round Bar

69

Cut-Off Area

(a)

(b)

Fig 3-22 Cut-Off Area of SUM 43 (a) 1 Round Bar and (b) 5 Round Bar

70

SUM 43 Nickel Round Bar

Fig 3-23 SUM 43 Nickel Material

Number 4 5

Hardness(HRB) 51 50

Yield Stress (MPa) 1580 1544

Tensile Strength (MPa) 1639 1625

Poissonrsquos Ratio 03 028

Youngrsquos Modulus (GPa) 194 201

Cut-off Area Shrinking () 1697 137

Elongation () 376 265

Table 3-9 Mechanical Properties of SUM 43 Nickel

71

Stress-Strain Diagrams

(a)

(b)

Fig 3-24 Stress-Strain Diagrams for (a) 4 Round Bar and (b) 5 Round Bar

72

Cut-Off Area

(a)

(b)

Fig 3-25 Cut-Off Area of (a) 4 Round Bar and (b) 5 Round Bar

73

SUM 43 Black Surface Material

Fig 3-26 SUM 43 Black Surface Material

Number 3 5

Hardness(HRB) 56 56

Yield Stress (MPa) 1416 1361

Tensile Strength (MPa) 1591 1402

Poissonrsquos Ratio 029 031

Youngrsquos Modulus (GPa) 200 202

Cut-off Area Shrinking () 139 124

Elongation () 24 24

Table 3-10 Mechanical Properties of SUM 43 Black Surface Material

74

Stress-Strain Diagrams

0 2 4 6 8 10 12 14

-200

0

200

400

600

800

1000

1200

1400

1600

1800

應力 (MPa)

應變()

(a)

0 2 4 6 8 10

-200

0

200

400

600

800

1000

1200

1400

1600

應力

(MPa)

位移 ()

(b)

Fig 3-27 Stress-Strain Diagrams for (a) 3 Round Bar and (b) 5 Round Bar

(Note These curves were formulated using Visual Solutions Inc VisSim Software)

75

Cut-Off Area

(a)

(b)

Fig 3-28 Cut-Off Area of (a) 3 Round Bar and (b) 5 Round Bar

76

The force value (N) was retrieved from the Universal Testing Machine

The Poissonrsquos Ratio (ε) is calculated as

ε =

the values for the Poissonrsquos Ratio are in average around 0297

The Youngrsquos Modulus (E) is calculated as

E =

Where

Stress =

Cross-sectional Area =

where D is the Diameter

The value for D was in average around 1258 mm

The values shown by the computer because there is Slippage phenomena between the Clamp and the

specimen will not be taken into consideration for the elongation strain and Youngrsquos modulus and we will

refer to the values that we have meticulously calculated

77

Chapter 4 AR COATING IN DEPTH

41 Experimentrsquos Purpose and Principles

By means of a vacuum chamber and several other instruments we intend to apply Anti-Reflective

Coating using deposition process to a laser diode and in this way reduce its refraction so as to make it

lose less light in the process of amplification and we can control certain wavelengths we want produced

for certain desired applications in our case we are attempting to re-create a Bose-Einstein Condensate

An optimal BEC apparatus is shown in figure 4-1

Fig 4-1 BEC Apparatus

The main point of this experiment is to build a vacuum chamber system attach all the instrumentation

needed (Vacuum pump deposition meter and voltmeter) and use it to apply AR coating to a laser diode

After we have accomplished the AR coating other team will be in charge of designing the BEC apparatus

and use the results of our research

78

42 Experimentrsquos Equipment

421 Vacuum Chamber

For this research we designed a vacuum chamber whose main body is shown in figure 4-2 Its

dimensions are

Width 240 mm

Length 240 mm

Height 200 mm

Outer Diameter 4 in

Inner Diameter 15 in

Fig 4-2 Vacuum Chamber Main Body

The chamber is made up of 6 pass ways pass way A is the connection with the Laser Deposition

Equipment pass way B is the connection with the Turbo Pump and pass way C is for the connection with

the Deposition Source

A

C

B

79

Pass way C is for the deposition source as mentioned above This is a system where a thermal

resistance is heated by passing a high current through it which heats up a filament boat (made of tungsten)

where the material to be evaporated is place We control the temperature as such that the material will

evaporate and the heat will not cause the filament boat to crack

Because P = Isup2 R (where P is power I is current and R is resistance) to avoid the current to flow

where it is not desired we decided that the material for the Thermocouple shown in figure 4-3 should be

Copper ᴓ 63 mm We choose it that way because Copper has very good heat dissipation characteristics

and the resistance value is low It can reduce the value of the current enough to make the thermocouple to

create heat

Fig 4-3 Thermocouple

To the thermocouple we attach the tungsten filament boat We need to take notice of materials to be

used in this design because when using high current the tungsten filament boar will heat up and so the

material must be able to keep up with the heating potential of tungsten and has a low coefficient of heat

dissipation to avoid the tungsten to fail when heating up and therefore not evaporating Considering all

this we decide to use Stainless Steel

Because this clamp will be assembled inside the chamber after many revisions it was determined it

will have the shape shown in figure 4-4

Fig 4-4 Filament Boat Clamp Design

80

For the tungsten filament boat we bought the product from a distributor The dimensions are

Length 100 mm

Width 10 mm

Height 1 mm

Our thermocouple is 15 in but the pass way C is 4 in so we need to attach a Flange that connects

15in to 4in Because these specifications are quite difficult to achieve by Milling we had to use

electrical wire cutting

For the laser clamping system where the laser that is going to be AR coated will be placed will be

connected to pass way A the assembly is shown in figure 4-5 below

Fig 4-5 Cover Assembly

For this design we used an O-ring instead of a gasket so as to save time The design of the assembly

where the laser will be placed is shown in figure 4-6

Fig 4-6 Upper Cover Inner Assembly

D

E

F

81

Point D is the plate in the assembly where the laser diode will be fixed Because of the easy

processing we decide to use Aluminum and it is screwed to the top cover Point E is the connection for

the Quartz crystal resonator and it is designed in the same as point F in this way the results of the quartz

microbalance system will be more accurate in real time Point F is the final resting place for the laser

diode We use a Thor Labs Base with dimensions of ᴓ 9mm and ᴓ 56mm for two different size laser

diodes It just needs to be plugged in for easy installation

From figure 4-6 we know that the system needs signal system connections and because of the

change in temperature inside the chamber this could affect the functioning of the quartz microbalance so

we also need to install water tubes for cooling This is shown in figure 4-7 below

Fig 4-7 Diagram of Upper Cover Connections

In figure 4-8 we show the Feed through connections and their functions

Fig 4-8 Feed through Diagram

82

1 SQM-160 wire 5 Laser Connection 1 (Vin)

2 SQM-160 (G) 6 Laser Connection 2 (G)

3 K-Type-1 7 Laser Connection 3 (PD)

4 K-Type-2 8 Not In Use

The fully assembled chamber is shown in figure 4-9

Fig 4-9 Fully Assembled Chamber

422 Quartz Crystal Microbalance

For measuring the deposition on our target for coating we used the Inficon SQM-160 RateThickness

Monitor It is an easy to use instrument for measuring many types of thin-film coatings as shown in

figure 4-10

(a) Front Panel (b) Back Panel

Fig 4-10 Inficon SQM-160

83

Table 4-1 shows the technical specifications for this equipment

Number of sensors 2 Standard 4 additional optional

Sensor Frequency Range 40 MHz ~ 60 MHz

Reference Frequency Accuracy 002

Thickness Display Resolution 1 Aring

Thickness Resolution 015 Aring (Std) 0037 Aring (Hi Res)

Density of Stored Films 05-9999 gmcc

Tooling 10-399

Z-Factor 010-1000

Final Thickness 0000-9999k Aring

Measurement Period 15 to 2 sec

Simulation Mode Yes

Frequency Mode Yes

Rate Resolution 011 Arings

Dual Crystal Yes

Etch Mode Yes

Crystal Tooling 10-399

Crystal Fail Min Max 40 to 60 MHz 41 to 61 MHz

Power 100-120 200-240~plusmn10 nominal 20W

Operation Environment 0degC ~ 50degC

0 ~ 80 RH non-condensing

0 ~ 2000 meters

Class 1 Equipment

Pollution Degree 2

Rack Dimensions 885mm x 2127mm x 1969mm

Weight 27 kg

Table 4-1 Inficon SQM-160 RateThickness Monitor Specs

84

To the SQM-160 we need to connect an Oscillator We use the Sigma Instruments Remote Oscillator

Ser No 2 268 as shown in figure 4-11

Fig 4-11 Sigma Instruments Remote Oscillator

The connections diagram is shown in figure 4-12

Fig 4-12 SQM-160 Connections Diagram

85

423 Turbo Pump

For our experiments we used the Pfeiffer TCP 015 Electronic Drive Unit shown below in figure 4-13

Table 4-2 shows the technical specifications for this equipment

(a) Front Panel (b) Back Panel

Fig 4-13 Pfeiffer TCP 015 Electronic Drive

Connection Voltage (100V) 90-112

Mains Frequency 5060 Hz

Start-up Current 22 A

Nominal Frequency 1500 Hz

Rotation Speed 10V = 1500Hz plusmn2

Analog Output Current 10 V = 25 A plusmn 5

Rotation Speed Switchpoint 750 Hz

Works Setting 8 min

Permissible Ambient Temperature 0degC ~ 40degC

Dimensions Front Panel 1285mm x 1063mm

Insertion Length 227mm

Weight 27 Kg

Table 4-2 Pfeiffer TCP 015 Electronic Drive Specs

86

The connections diagram is shown in figure 4-14

Fig 4-14Connections Diagram for Pfeiffer TCP 015

To measure the pressure inside the chamber we use the Granville Phillips 375 Convectron Vacuum

Pressure Controller shown in figure 4-15

(a) Front Panel (b) Back Panel

Fig 4-15 Granville Phillips 375 Convectron

87

Its dimensions are shown in figure 4-16

Fig 4-16 Dimensions of Convectron

Table 4-3 shows the technical specifications for this equipment

Table 4-3 Granville Phillips 375 Convectron Vacuum Pressure Controller Specs

88

424 Multimeter

For our experiment we used the Keithley 2000 Digital Multimeter as shown in figure 4-17

(a) Front Panel (b) Back Panel

Fig 4-17 Keithley Model 2000 6-12-Digit Digital Multimeter

Its technical specifications are shown in table 4-4

Table 4-4 Keithley Model 2000 6-12-Digit Digital Multimeter Specs

89

43 Experiment Procedure

1 Connecting together the equipment and the chamber

(1) We first connect the resonator to the thickness monitor and connect the other side to the

chamber

(2) We now connect the flexible tubes to the turbo pump on one side and to the chamber on the

other

(3) We need to check that tubes are tightly connected to avoid any leaks in the vacuum pumping

process which will not allow us to get to our goal of Torr As shown in figure 4-18

(4) Connect the convectron to the system as shown in figure 4-19

Fig 4-18 checking for leaks using alcohol

Fig 4-19 Convectron attached to System

90

(5) Attach the clamps of the Multimeter to the bottom of the chamber as shown in figure 4-20

(6) Place the Quartz crystal in place

(7) Close tight vacuum chamber

(8) Connect all electrical appliances to power source

Fig 4-20 Multimeter Connections

2 Starting up the System

(1) We turn on all the devices as such Check all systems are ready to function Reset all values

that might be left over from previous tests

(2) Start the thickness monitor and set all values for this experiment In our case we got to testing

the system but not actual coating So we used the simulation mode of the thickness monitor as

shown in figure 4-21

Fig 4-21 Simulation Mode

91

(3) Start the turbo pump Make sure the lid on the vacuum chamber is tightly closed

(4) Start convectron and record initial pressure

(5) Start Multimeter and record initial current

3 Coating Process

(1) If we have the deposition material inside the filament boat the power source for the high

current must be started as well

(2) Record all initial values for thickness current pressure

(3) For an ideal experiment we need a thickness of around 101 nm a pressure of Torr and

a current of 300 A

44 Results

From previous experiments we have shown that we can turn a LED into a laser by means of AR

Coating In figure 4-22 shown below we can compare the actual results of a Diode before and after AR

coating From the blue line we can see that when the diode is at a current of 15mA its light will change

from LED to laser and if we look at the red line its critical current is around 30 to 35 mA

Fig 4-22 AR Coating Comparison for Laser Diodes

This means that the light emitted is not as strong as if the diode had been coated because inside the

chamber there must be some excitation first so the reflectivity of both sides inside the diode must be high

So because of the coating in one of the sides we have opened a door and let the light come out so the

critical current is risen as such and will be higher value than that of before the coating

92

In the following figures we can see the difference between before and after coating in a material The

thickness is around 1016 nm for this material

Fig 4-23 Before Coating

Fig 4-24 After Coating

93

Chapter 5 CONCLUSIONS AND RECOMMENDATIONS

51 Conclusions

For the first part of this independent study taking into consideration the data that came out of our

research and that sent by the provider we can say

1 SUM 23 after heat treatment will unexpectedly develop cracking in the middle of the tensile

testing process and suddenly break

2 Itrsquos possible that in the process of heat treatment to the SUM 23 material the treatment was not

uniform and this will create a pre-loaded moment force on one side that pushes on the other side

of the specimen resulting in material deformation

3 In the process of attaching the strain gauges to the materials it is very easy to make errors due to

poor adhesion or sudden removal in the tensile testing process

For our second part of the independent study the following can be made

1 At the beginning of this independent study we had no idea what Bose-Einstein Condensate was

or what was its purpose After much literature we finally comprehended the basic principles to

put into practice for our research

2 Our systemrsquos basic working principles and equipmentrsquos complexity are a little difficult to grasp

but hopefully we were able to understand enough of it

3 Theoretically from relation between the power and current we can know the advantages and

disadvantages of AR Coating

4 We were able to assemble the system and run test on its functions Even though we were able to

do this there is still much more work left to do with this system

52 Recommendations

For the Tensile Testing the following can be said

1 Ask the provider to check on the process of heat treatment on the SUM 23 material and give

them the information we have gathered through our test so they can correct for the mechanical

properties found if any change is needed

2 To avoid the problem of the inaccuracy of the poor adhesion of strain gauges we can attach

multiple strain gauges to the same one specimen so as to correlate data and improve our results

For the AR Coating the following can be said

1 We need to make sure that there are no physical defects on the main body of the chamber so as to

achieve maximum efficiency in the vacuum process If there was then the vacuum will arrive to

certain point and then start to decrease

2 It would be preferable to add some sort of visual aid that will allow the user to check the inside of

the chamber without actually opening it This will help us determine at what times we should

manipulate the current to better evaporate the substrate

94

REFERENCES

[1] A L Window Strain Gauge Technology Elsevier Applied Science London and New York 2nd

Edition 1992

[2] CC Perry and HR Lissner Strain Gauge Primer McGraw-Hill Book Co Inc New York 1955

[3] James W Dally William F Riley McGraw-Hill 1978

[4] University of Colorado Boulder BEC - What is it and where did the idea come from

httpwwwcoloradoeduphysics2000becwhat_is_ithtml

[5] Ultraslow Light amp Bose-Einstein Condensates Two-way Control with Coherent Light amp Atom

Fields Harvard Hau Lab Dr Lene Vestergaard Hau Optics amp Photonics News 16 1995

[6] The Art of Taming Light Ultra-slow and Stopped Light Harvard Hau Lab Dr Lene

Vestergaard Hau Europhysics News 2004

[7] Nonlinear Optics Shocking Superfluids Harvard Hau Lab Dr Lene Vestergaard Hau Nature

Physics 2007

[8] Model P3 Strain Indicator and Recorder Instruction Manual Vishay Micro-Measurements 2005

[9] Granville-Phillips Series 375 Convectron Vacuum Gauge Controller Instruction Manual Brooks

Automation 2008

[10] Effect of Film Thickness on the Validity of the Sauerbrey Equation for Hydrated Polyelectrolyte

Films Vogt Lin Wu White 2004

[11] Quartz Crystal Microbalance Study of DNA Immobilization and Hybridization for DNA Sensor

Development Chang Zhao 2008

[12] Installation of Strain Gages with SR-4 PrecoatAdhesive Vishay Micro-Measurements 2005

[13] Strain Gauge Measurement ndash A Tutorial National Instruments 1998

[14] Correlation between Vickers Hardness Number and Yield Stress of Cold-Formed Products

Yavuz Tekkaya

[15] httpsenwikipediaorg

Page 59: PC Hinge Materials Testing and AR Laser Diode Coating

59

Stress-Strain Diagram

(a)

60

(b)

(c)

(d)

61

Fig 3-15 Stress-Strain Diagrams for (a) 1 Round Bar (b) 2 Round Bar (c) 3 Round Bar and (d)

4 Round Bar

Cut-Off Area

(a)

(b)

62

(c)

(d)

Fig 3-16 Cut-Off Area of (a) 1 Round Bar (b) 2 Round Bar (c) 3 Round Bar and (d) 4 Round

Bar

63

SUM 23 Black Surface Round Bar

Fig 3-17 SUM 23 Black Surface Material

Number 1 2 3

Hardness(HRB) 51 50 51

Yield Stress (MPa) 378 371 369

Tensile Strength (MPa) 467 465 464

Poissonrsquos Ratio 03 016 04

Youngrsquos Modulus (GPa) 215 266 266

Cut-off Area Shrinking () 986 94 848

Elongation () 748 805 761

Table 3-7 Mechanical Properties of SUM 23 Black Surface Material

64

Stress-Strain Diagram

(a)

(b)

65

(c)

Fig 3-18 Stress-Strain Diagrams for (a) 1 Round Bar 2 Round Bar and (c) 3 Round Bar

Cut-Off Surface

(a)

66

(b)

(c)

Fig 3-19 Cut-Off Surface of (a) 1 Round Bar 2 Round Bar and (c) 3 Round Bar

67

342 SUM 43

Fig 3-20 Untreated SUM 43 Untreated Material

Number 1 5

Hardness(HRB) 76 75

Yield Stress (MPa) 572 594

Tensile Strength (MPa) 743 785

Poissonrsquos Ratio 027 029

Youngrsquos Modulus (GPa) 200 202

Cut-off Area Shrinking () 338 2944

Elongation () 857 894

Table 3-8 Mechanical Properties of SUM 43 Untreated

68

Stress-Strain Diagrams

(a)

(b)

Fig 3-21 Stress-Strain Diagrams for SUM 43 (a) 1 Round Bar and (b) 5 Round Bar

69

Cut-Off Area

(a)

(b)

Fig 3-22 Cut-Off Area of SUM 43 (a) 1 Round Bar and (b) 5 Round Bar

70

SUM 43 Nickel Round Bar

Fig 3-23 SUM 43 Nickel Material

Number 4 5

Hardness(HRB) 51 50

Yield Stress (MPa) 1580 1544

Tensile Strength (MPa) 1639 1625

Poissonrsquos Ratio 03 028

Youngrsquos Modulus (GPa) 194 201

Cut-off Area Shrinking () 1697 137

Elongation () 376 265

Table 3-9 Mechanical Properties of SUM 43 Nickel

71

Stress-Strain Diagrams

(a)

(b)

Fig 3-24 Stress-Strain Diagrams for (a) 4 Round Bar and (b) 5 Round Bar

72

Cut-Off Area

(a)

(b)

Fig 3-25 Cut-Off Area of (a) 4 Round Bar and (b) 5 Round Bar

73

SUM 43 Black Surface Material

Fig 3-26 SUM 43 Black Surface Material

Number 3 5

Hardness(HRB) 56 56

Yield Stress (MPa) 1416 1361

Tensile Strength (MPa) 1591 1402

Poissonrsquos Ratio 029 031

Youngrsquos Modulus (GPa) 200 202

Cut-off Area Shrinking () 139 124

Elongation () 24 24

Table 3-10 Mechanical Properties of SUM 43 Black Surface Material

74

Stress-Strain Diagrams

0 2 4 6 8 10 12 14

-200

0

200

400

600

800

1000

1200

1400

1600

1800

應力 (MPa)

應變()

(a)

0 2 4 6 8 10

-200

0

200

400

600

800

1000

1200

1400

1600

應力

(MPa)

位移 ()

(b)

Fig 3-27 Stress-Strain Diagrams for (a) 3 Round Bar and (b) 5 Round Bar

(Note These curves were formulated using Visual Solutions Inc VisSim Software)

75

Cut-Off Area

(a)

(b)

Fig 3-28 Cut-Off Area of (a) 3 Round Bar and (b) 5 Round Bar

76

The force value (N) was retrieved from the Universal Testing Machine

The Poissonrsquos Ratio (ε) is calculated as

ε =

the values for the Poissonrsquos Ratio are in average around 0297

The Youngrsquos Modulus (E) is calculated as

E =

Where

Stress =

Cross-sectional Area =

where D is the Diameter

The value for D was in average around 1258 mm

The values shown by the computer because there is Slippage phenomena between the Clamp and the

specimen will not be taken into consideration for the elongation strain and Youngrsquos modulus and we will

refer to the values that we have meticulously calculated

77

Chapter 4 AR COATING IN DEPTH

41 Experimentrsquos Purpose and Principles

By means of a vacuum chamber and several other instruments we intend to apply Anti-Reflective

Coating using deposition process to a laser diode and in this way reduce its refraction so as to make it

lose less light in the process of amplification and we can control certain wavelengths we want produced

for certain desired applications in our case we are attempting to re-create a Bose-Einstein Condensate

An optimal BEC apparatus is shown in figure 4-1

Fig 4-1 BEC Apparatus

The main point of this experiment is to build a vacuum chamber system attach all the instrumentation

needed (Vacuum pump deposition meter and voltmeter) and use it to apply AR coating to a laser diode

After we have accomplished the AR coating other team will be in charge of designing the BEC apparatus

and use the results of our research

78

42 Experimentrsquos Equipment

421 Vacuum Chamber

For this research we designed a vacuum chamber whose main body is shown in figure 4-2 Its

dimensions are

Width 240 mm

Length 240 mm

Height 200 mm

Outer Diameter 4 in

Inner Diameter 15 in

Fig 4-2 Vacuum Chamber Main Body

The chamber is made up of 6 pass ways pass way A is the connection with the Laser Deposition

Equipment pass way B is the connection with the Turbo Pump and pass way C is for the connection with

the Deposition Source

A

C

B

79

Pass way C is for the deposition source as mentioned above This is a system where a thermal

resistance is heated by passing a high current through it which heats up a filament boat (made of tungsten)

where the material to be evaporated is place We control the temperature as such that the material will

evaporate and the heat will not cause the filament boat to crack

Because P = Isup2 R (where P is power I is current and R is resistance) to avoid the current to flow

where it is not desired we decided that the material for the Thermocouple shown in figure 4-3 should be

Copper ᴓ 63 mm We choose it that way because Copper has very good heat dissipation characteristics

and the resistance value is low It can reduce the value of the current enough to make the thermocouple to

create heat

Fig 4-3 Thermocouple

To the thermocouple we attach the tungsten filament boat We need to take notice of materials to be

used in this design because when using high current the tungsten filament boar will heat up and so the

material must be able to keep up with the heating potential of tungsten and has a low coefficient of heat

dissipation to avoid the tungsten to fail when heating up and therefore not evaporating Considering all

this we decide to use Stainless Steel

Because this clamp will be assembled inside the chamber after many revisions it was determined it

will have the shape shown in figure 4-4

Fig 4-4 Filament Boat Clamp Design

80

For the tungsten filament boat we bought the product from a distributor The dimensions are

Length 100 mm

Width 10 mm

Height 1 mm

Our thermocouple is 15 in but the pass way C is 4 in so we need to attach a Flange that connects

15in to 4in Because these specifications are quite difficult to achieve by Milling we had to use

electrical wire cutting

For the laser clamping system where the laser that is going to be AR coated will be placed will be

connected to pass way A the assembly is shown in figure 4-5 below

Fig 4-5 Cover Assembly

For this design we used an O-ring instead of a gasket so as to save time The design of the assembly

where the laser will be placed is shown in figure 4-6

Fig 4-6 Upper Cover Inner Assembly

D

E

F

81

Point D is the plate in the assembly where the laser diode will be fixed Because of the easy

processing we decide to use Aluminum and it is screwed to the top cover Point E is the connection for

the Quartz crystal resonator and it is designed in the same as point F in this way the results of the quartz

microbalance system will be more accurate in real time Point F is the final resting place for the laser

diode We use a Thor Labs Base with dimensions of ᴓ 9mm and ᴓ 56mm for two different size laser

diodes It just needs to be plugged in for easy installation

From figure 4-6 we know that the system needs signal system connections and because of the

change in temperature inside the chamber this could affect the functioning of the quartz microbalance so

we also need to install water tubes for cooling This is shown in figure 4-7 below

Fig 4-7 Diagram of Upper Cover Connections

In figure 4-8 we show the Feed through connections and their functions

Fig 4-8 Feed through Diagram

82

1 SQM-160 wire 5 Laser Connection 1 (Vin)

2 SQM-160 (G) 6 Laser Connection 2 (G)

3 K-Type-1 7 Laser Connection 3 (PD)

4 K-Type-2 8 Not In Use

The fully assembled chamber is shown in figure 4-9

Fig 4-9 Fully Assembled Chamber

422 Quartz Crystal Microbalance

For measuring the deposition on our target for coating we used the Inficon SQM-160 RateThickness

Monitor It is an easy to use instrument for measuring many types of thin-film coatings as shown in

figure 4-10

(a) Front Panel (b) Back Panel

Fig 4-10 Inficon SQM-160

83

Table 4-1 shows the technical specifications for this equipment

Number of sensors 2 Standard 4 additional optional

Sensor Frequency Range 40 MHz ~ 60 MHz

Reference Frequency Accuracy 002

Thickness Display Resolution 1 Aring

Thickness Resolution 015 Aring (Std) 0037 Aring (Hi Res)

Density of Stored Films 05-9999 gmcc

Tooling 10-399

Z-Factor 010-1000

Final Thickness 0000-9999k Aring

Measurement Period 15 to 2 sec

Simulation Mode Yes

Frequency Mode Yes

Rate Resolution 011 Arings

Dual Crystal Yes

Etch Mode Yes

Crystal Tooling 10-399

Crystal Fail Min Max 40 to 60 MHz 41 to 61 MHz

Power 100-120 200-240~plusmn10 nominal 20W

Operation Environment 0degC ~ 50degC

0 ~ 80 RH non-condensing

0 ~ 2000 meters

Class 1 Equipment

Pollution Degree 2

Rack Dimensions 885mm x 2127mm x 1969mm

Weight 27 kg

Table 4-1 Inficon SQM-160 RateThickness Monitor Specs

84

To the SQM-160 we need to connect an Oscillator We use the Sigma Instruments Remote Oscillator

Ser No 2 268 as shown in figure 4-11

Fig 4-11 Sigma Instruments Remote Oscillator

The connections diagram is shown in figure 4-12

Fig 4-12 SQM-160 Connections Diagram

85

423 Turbo Pump

For our experiments we used the Pfeiffer TCP 015 Electronic Drive Unit shown below in figure 4-13

Table 4-2 shows the technical specifications for this equipment

(a) Front Panel (b) Back Panel

Fig 4-13 Pfeiffer TCP 015 Electronic Drive

Connection Voltage (100V) 90-112

Mains Frequency 5060 Hz

Start-up Current 22 A

Nominal Frequency 1500 Hz

Rotation Speed 10V = 1500Hz plusmn2

Analog Output Current 10 V = 25 A plusmn 5

Rotation Speed Switchpoint 750 Hz

Works Setting 8 min

Permissible Ambient Temperature 0degC ~ 40degC

Dimensions Front Panel 1285mm x 1063mm

Insertion Length 227mm

Weight 27 Kg

Table 4-2 Pfeiffer TCP 015 Electronic Drive Specs

86

The connections diagram is shown in figure 4-14

Fig 4-14Connections Diagram for Pfeiffer TCP 015

To measure the pressure inside the chamber we use the Granville Phillips 375 Convectron Vacuum

Pressure Controller shown in figure 4-15

(a) Front Panel (b) Back Panel

Fig 4-15 Granville Phillips 375 Convectron

87

Its dimensions are shown in figure 4-16

Fig 4-16 Dimensions of Convectron

Table 4-3 shows the technical specifications for this equipment

Table 4-3 Granville Phillips 375 Convectron Vacuum Pressure Controller Specs

88

424 Multimeter

For our experiment we used the Keithley 2000 Digital Multimeter as shown in figure 4-17

(a) Front Panel (b) Back Panel

Fig 4-17 Keithley Model 2000 6-12-Digit Digital Multimeter

Its technical specifications are shown in table 4-4

Table 4-4 Keithley Model 2000 6-12-Digit Digital Multimeter Specs

89

43 Experiment Procedure

1 Connecting together the equipment and the chamber

(1) We first connect the resonator to the thickness monitor and connect the other side to the

chamber

(2) We now connect the flexible tubes to the turbo pump on one side and to the chamber on the

other

(3) We need to check that tubes are tightly connected to avoid any leaks in the vacuum pumping

process which will not allow us to get to our goal of Torr As shown in figure 4-18

(4) Connect the convectron to the system as shown in figure 4-19

Fig 4-18 checking for leaks using alcohol

Fig 4-19 Convectron attached to System

90

(5) Attach the clamps of the Multimeter to the bottom of the chamber as shown in figure 4-20

(6) Place the Quartz crystal in place

(7) Close tight vacuum chamber

(8) Connect all electrical appliances to power source

Fig 4-20 Multimeter Connections

2 Starting up the System

(1) We turn on all the devices as such Check all systems are ready to function Reset all values

that might be left over from previous tests

(2) Start the thickness monitor and set all values for this experiment In our case we got to testing

the system but not actual coating So we used the simulation mode of the thickness monitor as

shown in figure 4-21

Fig 4-21 Simulation Mode

91

(3) Start the turbo pump Make sure the lid on the vacuum chamber is tightly closed

(4) Start convectron and record initial pressure

(5) Start Multimeter and record initial current

3 Coating Process

(1) If we have the deposition material inside the filament boat the power source for the high

current must be started as well

(2) Record all initial values for thickness current pressure

(3) For an ideal experiment we need a thickness of around 101 nm a pressure of Torr and

a current of 300 A

44 Results

From previous experiments we have shown that we can turn a LED into a laser by means of AR

Coating In figure 4-22 shown below we can compare the actual results of a Diode before and after AR

coating From the blue line we can see that when the diode is at a current of 15mA its light will change

from LED to laser and if we look at the red line its critical current is around 30 to 35 mA

Fig 4-22 AR Coating Comparison for Laser Diodes

This means that the light emitted is not as strong as if the diode had been coated because inside the

chamber there must be some excitation first so the reflectivity of both sides inside the diode must be high

So because of the coating in one of the sides we have opened a door and let the light come out so the

critical current is risen as such and will be higher value than that of before the coating

92

In the following figures we can see the difference between before and after coating in a material The

thickness is around 1016 nm for this material

Fig 4-23 Before Coating

Fig 4-24 After Coating

93

Chapter 5 CONCLUSIONS AND RECOMMENDATIONS

51 Conclusions

For the first part of this independent study taking into consideration the data that came out of our

research and that sent by the provider we can say

1 SUM 23 after heat treatment will unexpectedly develop cracking in the middle of the tensile

testing process and suddenly break

2 Itrsquos possible that in the process of heat treatment to the SUM 23 material the treatment was not

uniform and this will create a pre-loaded moment force on one side that pushes on the other side

of the specimen resulting in material deformation

3 In the process of attaching the strain gauges to the materials it is very easy to make errors due to

poor adhesion or sudden removal in the tensile testing process

For our second part of the independent study the following can be made

1 At the beginning of this independent study we had no idea what Bose-Einstein Condensate was

or what was its purpose After much literature we finally comprehended the basic principles to

put into practice for our research

2 Our systemrsquos basic working principles and equipmentrsquos complexity are a little difficult to grasp

but hopefully we were able to understand enough of it

3 Theoretically from relation between the power and current we can know the advantages and

disadvantages of AR Coating

4 We were able to assemble the system and run test on its functions Even though we were able to

do this there is still much more work left to do with this system

52 Recommendations

For the Tensile Testing the following can be said

1 Ask the provider to check on the process of heat treatment on the SUM 23 material and give

them the information we have gathered through our test so they can correct for the mechanical

properties found if any change is needed

2 To avoid the problem of the inaccuracy of the poor adhesion of strain gauges we can attach

multiple strain gauges to the same one specimen so as to correlate data and improve our results

For the AR Coating the following can be said

1 We need to make sure that there are no physical defects on the main body of the chamber so as to

achieve maximum efficiency in the vacuum process If there was then the vacuum will arrive to

certain point and then start to decrease

2 It would be preferable to add some sort of visual aid that will allow the user to check the inside of

the chamber without actually opening it This will help us determine at what times we should

manipulate the current to better evaporate the substrate

94

REFERENCES

[1] A L Window Strain Gauge Technology Elsevier Applied Science London and New York 2nd

Edition 1992

[2] CC Perry and HR Lissner Strain Gauge Primer McGraw-Hill Book Co Inc New York 1955

[3] James W Dally William F Riley McGraw-Hill 1978

[4] University of Colorado Boulder BEC - What is it and where did the idea come from

httpwwwcoloradoeduphysics2000becwhat_is_ithtml

[5] Ultraslow Light amp Bose-Einstein Condensates Two-way Control with Coherent Light amp Atom

Fields Harvard Hau Lab Dr Lene Vestergaard Hau Optics amp Photonics News 16 1995

[6] The Art of Taming Light Ultra-slow and Stopped Light Harvard Hau Lab Dr Lene

Vestergaard Hau Europhysics News 2004

[7] Nonlinear Optics Shocking Superfluids Harvard Hau Lab Dr Lene Vestergaard Hau Nature

Physics 2007

[8] Model P3 Strain Indicator and Recorder Instruction Manual Vishay Micro-Measurements 2005

[9] Granville-Phillips Series 375 Convectron Vacuum Gauge Controller Instruction Manual Brooks

Automation 2008

[10] Effect of Film Thickness on the Validity of the Sauerbrey Equation for Hydrated Polyelectrolyte

Films Vogt Lin Wu White 2004

[11] Quartz Crystal Microbalance Study of DNA Immobilization and Hybridization for DNA Sensor

Development Chang Zhao 2008

[12] Installation of Strain Gages with SR-4 PrecoatAdhesive Vishay Micro-Measurements 2005

[13] Strain Gauge Measurement ndash A Tutorial National Instruments 1998

[14] Correlation between Vickers Hardness Number and Yield Stress of Cold-Formed Products

Yavuz Tekkaya

[15] httpsenwikipediaorg

Page 60: PC Hinge Materials Testing and AR Laser Diode Coating

60

(b)

(c)

(d)

61

Fig 3-15 Stress-Strain Diagrams for (a) 1 Round Bar (b) 2 Round Bar (c) 3 Round Bar and (d)

4 Round Bar

Cut-Off Area

(a)

(b)

62

(c)

(d)

Fig 3-16 Cut-Off Area of (a) 1 Round Bar (b) 2 Round Bar (c) 3 Round Bar and (d) 4 Round

Bar

63

SUM 23 Black Surface Round Bar

Fig 3-17 SUM 23 Black Surface Material

Number 1 2 3

Hardness(HRB) 51 50 51

Yield Stress (MPa) 378 371 369

Tensile Strength (MPa) 467 465 464

Poissonrsquos Ratio 03 016 04

Youngrsquos Modulus (GPa) 215 266 266

Cut-off Area Shrinking () 986 94 848

Elongation () 748 805 761

Table 3-7 Mechanical Properties of SUM 23 Black Surface Material

64

Stress-Strain Diagram

(a)

(b)

65

(c)

Fig 3-18 Stress-Strain Diagrams for (a) 1 Round Bar 2 Round Bar and (c) 3 Round Bar

Cut-Off Surface

(a)

66

(b)

(c)

Fig 3-19 Cut-Off Surface of (a) 1 Round Bar 2 Round Bar and (c) 3 Round Bar

67

342 SUM 43

Fig 3-20 Untreated SUM 43 Untreated Material

Number 1 5

Hardness(HRB) 76 75

Yield Stress (MPa) 572 594

Tensile Strength (MPa) 743 785

Poissonrsquos Ratio 027 029

Youngrsquos Modulus (GPa) 200 202

Cut-off Area Shrinking () 338 2944

Elongation () 857 894

Table 3-8 Mechanical Properties of SUM 43 Untreated

68

Stress-Strain Diagrams

(a)

(b)

Fig 3-21 Stress-Strain Diagrams for SUM 43 (a) 1 Round Bar and (b) 5 Round Bar

69

Cut-Off Area

(a)

(b)

Fig 3-22 Cut-Off Area of SUM 43 (a) 1 Round Bar and (b) 5 Round Bar

70

SUM 43 Nickel Round Bar

Fig 3-23 SUM 43 Nickel Material

Number 4 5

Hardness(HRB) 51 50

Yield Stress (MPa) 1580 1544

Tensile Strength (MPa) 1639 1625

Poissonrsquos Ratio 03 028

Youngrsquos Modulus (GPa) 194 201

Cut-off Area Shrinking () 1697 137

Elongation () 376 265

Table 3-9 Mechanical Properties of SUM 43 Nickel

71

Stress-Strain Diagrams

(a)

(b)

Fig 3-24 Stress-Strain Diagrams for (a) 4 Round Bar and (b) 5 Round Bar

72

Cut-Off Area

(a)

(b)

Fig 3-25 Cut-Off Area of (a) 4 Round Bar and (b) 5 Round Bar

73

SUM 43 Black Surface Material

Fig 3-26 SUM 43 Black Surface Material

Number 3 5

Hardness(HRB) 56 56

Yield Stress (MPa) 1416 1361

Tensile Strength (MPa) 1591 1402

Poissonrsquos Ratio 029 031

Youngrsquos Modulus (GPa) 200 202

Cut-off Area Shrinking () 139 124

Elongation () 24 24

Table 3-10 Mechanical Properties of SUM 43 Black Surface Material

74

Stress-Strain Diagrams

0 2 4 6 8 10 12 14

-200

0

200

400

600

800

1000

1200

1400

1600

1800

應力 (MPa)

應變()

(a)

0 2 4 6 8 10

-200

0

200

400

600

800

1000

1200

1400

1600

應力

(MPa)

位移 ()

(b)

Fig 3-27 Stress-Strain Diagrams for (a) 3 Round Bar and (b) 5 Round Bar

(Note These curves were formulated using Visual Solutions Inc VisSim Software)

75

Cut-Off Area

(a)

(b)

Fig 3-28 Cut-Off Area of (a) 3 Round Bar and (b) 5 Round Bar

76

The force value (N) was retrieved from the Universal Testing Machine

The Poissonrsquos Ratio (ε) is calculated as

ε =

the values for the Poissonrsquos Ratio are in average around 0297

The Youngrsquos Modulus (E) is calculated as

E =

Where

Stress =

Cross-sectional Area =

where D is the Diameter

The value for D was in average around 1258 mm

The values shown by the computer because there is Slippage phenomena between the Clamp and the

specimen will not be taken into consideration for the elongation strain and Youngrsquos modulus and we will

refer to the values that we have meticulously calculated

77

Chapter 4 AR COATING IN DEPTH

41 Experimentrsquos Purpose and Principles

By means of a vacuum chamber and several other instruments we intend to apply Anti-Reflective

Coating using deposition process to a laser diode and in this way reduce its refraction so as to make it

lose less light in the process of amplification and we can control certain wavelengths we want produced

for certain desired applications in our case we are attempting to re-create a Bose-Einstein Condensate

An optimal BEC apparatus is shown in figure 4-1

Fig 4-1 BEC Apparatus

The main point of this experiment is to build a vacuum chamber system attach all the instrumentation

needed (Vacuum pump deposition meter and voltmeter) and use it to apply AR coating to a laser diode

After we have accomplished the AR coating other team will be in charge of designing the BEC apparatus

and use the results of our research

78

42 Experimentrsquos Equipment

421 Vacuum Chamber

For this research we designed a vacuum chamber whose main body is shown in figure 4-2 Its

dimensions are

Width 240 mm

Length 240 mm

Height 200 mm

Outer Diameter 4 in

Inner Diameter 15 in

Fig 4-2 Vacuum Chamber Main Body

The chamber is made up of 6 pass ways pass way A is the connection with the Laser Deposition

Equipment pass way B is the connection with the Turbo Pump and pass way C is for the connection with

the Deposition Source

A

C

B

79

Pass way C is for the deposition source as mentioned above This is a system where a thermal

resistance is heated by passing a high current through it which heats up a filament boat (made of tungsten)

where the material to be evaporated is place We control the temperature as such that the material will

evaporate and the heat will not cause the filament boat to crack

Because P = Isup2 R (where P is power I is current and R is resistance) to avoid the current to flow

where it is not desired we decided that the material for the Thermocouple shown in figure 4-3 should be

Copper ᴓ 63 mm We choose it that way because Copper has very good heat dissipation characteristics

and the resistance value is low It can reduce the value of the current enough to make the thermocouple to

create heat

Fig 4-3 Thermocouple

To the thermocouple we attach the tungsten filament boat We need to take notice of materials to be

used in this design because when using high current the tungsten filament boar will heat up and so the

material must be able to keep up with the heating potential of tungsten and has a low coefficient of heat

dissipation to avoid the tungsten to fail when heating up and therefore not evaporating Considering all

this we decide to use Stainless Steel

Because this clamp will be assembled inside the chamber after many revisions it was determined it

will have the shape shown in figure 4-4

Fig 4-4 Filament Boat Clamp Design

80

For the tungsten filament boat we bought the product from a distributor The dimensions are

Length 100 mm

Width 10 mm

Height 1 mm

Our thermocouple is 15 in but the pass way C is 4 in so we need to attach a Flange that connects

15in to 4in Because these specifications are quite difficult to achieve by Milling we had to use

electrical wire cutting

For the laser clamping system where the laser that is going to be AR coated will be placed will be

connected to pass way A the assembly is shown in figure 4-5 below

Fig 4-5 Cover Assembly

For this design we used an O-ring instead of a gasket so as to save time The design of the assembly

where the laser will be placed is shown in figure 4-6

Fig 4-6 Upper Cover Inner Assembly

D

E

F

81

Point D is the plate in the assembly where the laser diode will be fixed Because of the easy

processing we decide to use Aluminum and it is screwed to the top cover Point E is the connection for

the Quartz crystal resonator and it is designed in the same as point F in this way the results of the quartz

microbalance system will be more accurate in real time Point F is the final resting place for the laser

diode We use a Thor Labs Base with dimensions of ᴓ 9mm and ᴓ 56mm for two different size laser

diodes It just needs to be plugged in for easy installation

From figure 4-6 we know that the system needs signal system connections and because of the

change in temperature inside the chamber this could affect the functioning of the quartz microbalance so

we also need to install water tubes for cooling This is shown in figure 4-7 below

Fig 4-7 Diagram of Upper Cover Connections

In figure 4-8 we show the Feed through connections and their functions

Fig 4-8 Feed through Diagram

82

1 SQM-160 wire 5 Laser Connection 1 (Vin)

2 SQM-160 (G) 6 Laser Connection 2 (G)

3 K-Type-1 7 Laser Connection 3 (PD)

4 K-Type-2 8 Not In Use

The fully assembled chamber is shown in figure 4-9

Fig 4-9 Fully Assembled Chamber

422 Quartz Crystal Microbalance

For measuring the deposition on our target for coating we used the Inficon SQM-160 RateThickness

Monitor It is an easy to use instrument for measuring many types of thin-film coatings as shown in

figure 4-10

(a) Front Panel (b) Back Panel

Fig 4-10 Inficon SQM-160

83

Table 4-1 shows the technical specifications for this equipment

Number of sensors 2 Standard 4 additional optional

Sensor Frequency Range 40 MHz ~ 60 MHz

Reference Frequency Accuracy 002

Thickness Display Resolution 1 Aring

Thickness Resolution 015 Aring (Std) 0037 Aring (Hi Res)

Density of Stored Films 05-9999 gmcc

Tooling 10-399

Z-Factor 010-1000

Final Thickness 0000-9999k Aring

Measurement Period 15 to 2 sec

Simulation Mode Yes

Frequency Mode Yes

Rate Resolution 011 Arings

Dual Crystal Yes

Etch Mode Yes

Crystal Tooling 10-399

Crystal Fail Min Max 40 to 60 MHz 41 to 61 MHz

Power 100-120 200-240~plusmn10 nominal 20W

Operation Environment 0degC ~ 50degC

0 ~ 80 RH non-condensing

0 ~ 2000 meters

Class 1 Equipment

Pollution Degree 2

Rack Dimensions 885mm x 2127mm x 1969mm

Weight 27 kg

Table 4-1 Inficon SQM-160 RateThickness Monitor Specs

84

To the SQM-160 we need to connect an Oscillator We use the Sigma Instruments Remote Oscillator

Ser No 2 268 as shown in figure 4-11

Fig 4-11 Sigma Instruments Remote Oscillator

The connections diagram is shown in figure 4-12

Fig 4-12 SQM-160 Connections Diagram

85

423 Turbo Pump

For our experiments we used the Pfeiffer TCP 015 Electronic Drive Unit shown below in figure 4-13

Table 4-2 shows the technical specifications for this equipment

(a) Front Panel (b) Back Panel

Fig 4-13 Pfeiffer TCP 015 Electronic Drive

Connection Voltage (100V) 90-112

Mains Frequency 5060 Hz

Start-up Current 22 A

Nominal Frequency 1500 Hz

Rotation Speed 10V = 1500Hz plusmn2

Analog Output Current 10 V = 25 A plusmn 5

Rotation Speed Switchpoint 750 Hz

Works Setting 8 min

Permissible Ambient Temperature 0degC ~ 40degC

Dimensions Front Panel 1285mm x 1063mm

Insertion Length 227mm

Weight 27 Kg

Table 4-2 Pfeiffer TCP 015 Electronic Drive Specs

86

The connections diagram is shown in figure 4-14

Fig 4-14Connections Diagram for Pfeiffer TCP 015

To measure the pressure inside the chamber we use the Granville Phillips 375 Convectron Vacuum

Pressure Controller shown in figure 4-15

(a) Front Panel (b) Back Panel

Fig 4-15 Granville Phillips 375 Convectron

87

Its dimensions are shown in figure 4-16

Fig 4-16 Dimensions of Convectron

Table 4-3 shows the technical specifications for this equipment

Table 4-3 Granville Phillips 375 Convectron Vacuum Pressure Controller Specs

88

424 Multimeter

For our experiment we used the Keithley 2000 Digital Multimeter as shown in figure 4-17

(a) Front Panel (b) Back Panel

Fig 4-17 Keithley Model 2000 6-12-Digit Digital Multimeter

Its technical specifications are shown in table 4-4

Table 4-4 Keithley Model 2000 6-12-Digit Digital Multimeter Specs

89

43 Experiment Procedure

1 Connecting together the equipment and the chamber

(1) We first connect the resonator to the thickness monitor and connect the other side to the

chamber

(2) We now connect the flexible tubes to the turbo pump on one side and to the chamber on the

other

(3) We need to check that tubes are tightly connected to avoid any leaks in the vacuum pumping

process which will not allow us to get to our goal of Torr As shown in figure 4-18

(4) Connect the convectron to the system as shown in figure 4-19

Fig 4-18 checking for leaks using alcohol

Fig 4-19 Convectron attached to System

90

(5) Attach the clamps of the Multimeter to the bottom of the chamber as shown in figure 4-20

(6) Place the Quartz crystal in place

(7) Close tight vacuum chamber

(8) Connect all electrical appliances to power source

Fig 4-20 Multimeter Connections

2 Starting up the System

(1) We turn on all the devices as such Check all systems are ready to function Reset all values

that might be left over from previous tests

(2) Start the thickness monitor and set all values for this experiment In our case we got to testing

the system but not actual coating So we used the simulation mode of the thickness monitor as

shown in figure 4-21

Fig 4-21 Simulation Mode

91

(3) Start the turbo pump Make sure the lid on the vacuum chamber is tightly closed

(4) Start convectron and record initial pressure

(5) Start Multimeter and record initial current

3 Coating Process

(1) If we have the deposition material inside the filament boat the power source for the high

current must be started as well

(2) Record all initial values for thickness current pressure

(3) For an ideal experiment we need a thickness of around 101 nm a pressure of Torr and

a current of 300 A

44 Results

From previous experiments we have shown that we can turn a LED into a laser by means of AR

Coating In figure 4-22 shown below we can compare the actual results of a Diode before and after AR

coating From the blue line we can see that when the diode is at a current of 15mA its light will change

from LED to laser and if we look at the red line its critical current is around 30 to 35 mA

Fig 4-22 AR Coating Comparison for Laser Diodes

This means that the light emitted is not as strong as if the diode had been coated because inside the

chamber there must be some excitation first so the reflectivity of both sides inside the diode must be high

So because of the coating in one of the sides we have opened a door and let the light come out so the

critical current is risen as such and will be higher value than that of before the coating

92

In the following figures we can see the difference between before and after coating in a material The

thickness is around 1016 nm for this material

Fig 4-23 Before Coating

Fig 4-24 After Coating

93

Chapter 5 CONCLUSIONS AND RECOMMENDATIONS

51 Conclusions

For the first part of this independent study taking into consideration the data that came out of our

research and that sent by the provider we can say

1 SUM 23 after heat treatment will unexpectedly develop cracking in the middle of the tensile

testing process and suddenly break

2 Itrsquos possible that in the process of heat treatment to the SUM 23 material the treatment was not

uniform and this will create a pre-loaded moment force on one side that pushes on the other side

of the specimen resulting in material deformation

3 In the process of attaching the strain gauges to the materials it is very easy to make errors due to

poor adhesion or sudden removal in the tensile testing process

For our second part of the independent study the following can be made

1 At the beginning of this independent study we had no idea what Bose-Einstein Condensate was

or what was its purpose After much literature we finally comprehended the basic principles to

put into practice for our research

2 Our systemrsquos basic working principles and equipmentrsquos complexity are a little difficult to grasp

but hopefully we were able to understand enough of it

3 Theoretically from relation between the power and current we can know the advantages and

disadvantages of AR Coating

4 We were able to assemble the system and run test on its functions Even though we were able to

do this there is still much more work left to do with this system

52 Recommendations

For the Tensile Testing the following can be said

1 Ask the provider to check on the process of heat treatment on the SUM 23 material and give

them the information we have gathered through our test so they can correct for the mechanical

properties found if any change is needed

2 To avoid the problem of the inaccuracy of the poor adhesion of strain gauges we can attach

multiple strain gauges to the same one specimen so as to correlate data and improve our results

For the AR Coating the following can be said

1 We need to make sure that there are no physical defects on the main body of the chamber so as to

achieve maximum efficiency in the vacuum process If there was then the vacuum will arrive to

certain point and then start to decrease

2 It would be preferable to add some sort of visual aid that will allow the user to check the inside of

the chamber without actually opening it This will help us determine at what times we should

manipulate the current to better evaporate the substrate

94

REFERENCES

[1] A L Window Strain Gauge Technology Elsevier Applied Science London and New York 2nd

Edition 1992

[2] CC Perry and HR Lissner Strain Gauge Primer McGraw-Hill Book Co Inc New York 1955

[3] James W Dally William F Riley McGraw-Hill 1978

[4] University of Colorado Boulder BEC - What is it and where did the idea come from

httpwwwcoloradoeduphysics2000becwhat_is_ithtml

[5] Ultraslow Light amp Bose-Einstein Condensates Two-way Control with Coherent Light amp Atom

Fields Harvard Hau Lab Dr Lene Vestergaard Hau Optics amp Photonics News 16 1995

[6] The Art of Taming Light Ultra-slow and Stopped Light Harvard Hau Lab Dr Lene

Vestergaard Hau Europhysics News 2004

[7] Nonlinear Optics Shocking Superfluids Harvard Hau Lab Dr Lene Vestergaard Hau Nature

Physics 2007

[8] Model P3 Strain Indicator and Recorder Instruction Manual Vishay Micro-Measurements 2005

[9] Granville-Phillips Series 375 Convectron Vacuum Gauge Controller Instruction Manual Brooks

Automation 2008

[10] Effect of Film Thickness on the Validity of the Sauerbrey Equation for Hydrated Polyelectrolyte

Films Vogt Lin Wu White 2004

[11] Quartz Crystal Microbalance Study of DNA Immobilization and Hybridization for DNA Sensor

Development Chang Zhao 2008

[12] Installation of Strain Gages with SR-4 PrecoatAdhesive Vishay Micro-Measurements 2005

[13] Strain Gauge Measurement ndash A Tutorial National Instruments 1998

[14] Correlation between Vickers Hardness Number and Yield Stress of Cold-Formed Products

Yavuz Tekkaya

[15] httpsenwikipediaorg

Page 61: PC Hinge Materials Testing and AR Laser Diode Coating

61

Fig 3-15 Stress-Strain Diagrams for (a) 1 Round Bar (b) 2 Round Bar (c) 3 Round Bar and (d)

4 Round Bar

Cut-Off Area

(a)

(b)

62

(c)

(d)

Fig 3-16 Cut-Off Area of (a) 1 Round Bar (b) 2 Round Bar (c) 3 Round Bar and (d) 4 Round

Bar

63

SUM 23 Black Surface Round Bar

Fig 3-17 SUM 23 Black Surface Material

Number 1 2 3

Hardness(HRB) 51 50 51

Yield Stress (MPa) 378 371 369

Tensile Strength (MPa) 467 465 464

Poissonrsquos Ratio 03 016 04

Youngrsquos Modulus (GPa) 215 266 266

Cut-off Area Shrinking () 986 94 848

Elongation () 748 805 761

Table 3-7 Mechanical Properties of SUM 23 Black Surface Material

64

Stress-Strain Diagram

(a)

(b)

65

(c)

Fig 3-18 Stress-Strain Diagrams for (a) 1 Round Bar 2 Round Bar and (c) 3 Round Bar

Cut-Off Surface

(a)

66

(b)

(c)

Fig 3-19 Cut-Off Surface of (a) 1 Round Bar 2 Round Bar and (c) 3 Round Bar

67

342 SUM 43

Fig 3-20 Untreated SUM 43 Untreated Material

Number 1 5

Hardness(HRB) 76 75

Yield Stress (MPa) 572 594

Tensile Strength (MPa) 743 785

Poissonrsquos Ratio 027 029

Youngrsquos Modulus (GPa) 200 202

Cut-off Area Shrinking () 338 2944

Elongation () 857 894

Table 3-8 Mechanical Properties of SUM 43 Untreated

68

Stress-Strain Diagrams

(a)

(b)

Fig 3-21 Stress-Strain Diagrams for SUM 43 (a) 1 Round Bar and (b) 5 Round Bar

69

Cut-Off Area

(a)

(b)

Fig 3-22 Cut-Off Area of SUM 43 (a) 1 Round Bar and (b) 5 Round Bar

70

SUM 43 Nickel Round Bar

Fig 3-23 SUM 43 Nickel Material

Number 4 5

Hardness(HRB) 51 50

Yield Stress (MPa) 1580 1544

Tensile Strength (MPa) 1639 1625

Poissonrsquos Ratio 03 028

Youngrsquos Modulus (GPa) 194 201

Cut-off Area Shrinking () 1697 137

Elongation () 376 265

Table 3-9 Mechanical Properties of SUM 43 Nickel

71

Stress-Strain Diagrams

(a)

(b)

Fig 3-24 Stress-Strain Diagrams for (a) 4 Round Bar and (b) 5 Round Bar

72

Cut-Off Area

(a)

(b)

Fig 3-25 Cut-Off Area of (a) 4 Round Bar and (b) 5 Round Bar

73

SUM 43 Black Surface Material

Fig 3-26 SUM 43 Black Surface Material

Number 3 5

Hardness(HRB) 56 56

Yield Stress (MPa) 1416 1361

Tensile Strength (MPa) 1591 1402

Poissonrsquos Ratio 029 031

Youngrsquos Modulus (GPa) 200 202

Cut-off Area Shrinking () 139 124

Elongation () 24 24

Table 3-10 Mechanical Properties of SUM 43 Black Surface Material

74

Stress-Strain Diagrams

0 2 4 6 8 10 12 14

-200

0

200

400

600

800

1000

1200

1400

1600

1800

應力 (MPa)

應變()

(a)

0 2 4 6 8 10

-200

0

200

400

600

800

1000

1200

1400

1600

應力

(MPa)

位移 ()

(b)

Fig 3-27 Stress-Strain Diagrams for (a) 3 Round Bar and (b) 5 Round Bar

(Note These curves were formulated using Visual Solutions Inc VisSim Software)

75

Cut-Off Area

(a)

(b)

Fig 3-28 Cut-Off Area of (a) 3 Round Bar and (b) 5 Round Bar

76

The force value (N) was retrieved from the Universal Testing Machine

The Poissonrsquos Ratio (ε) is calculated as

ε =

the values for the Poissonrsquos Ratio are in average around 0297

The Youngrsquos Modulus (E) is calculated as

E =

Where

Stress =

Cross-sectional Area =

where D is the Diameter

The value for D was in average around 1258 mm

The values shown by the computer because there is Slippage phenomena between the Clamp and the

specimen will not be taken into consideration for the elongation strain and Youngrsquos modulus and we will

refer to the values that we have meticulously calculated

77

Chapter 4 AR COATING IN DEPTH

41 Experimentrsquos Purpose and Principles

By means of a vacuum chamber and several other instruments we intend to apply Anti-Reflective

Coating using deposition process to a laser diode and in this way reduce its refraction so as to make it

lose less light in the process of amplification and we can control certain wavelengths we want produced

for certain desired applications in our case we are attempting to re-create a Bose-Einstein Condensate

An optimal BEC apparatus is shown in figure 4-1

Fig 4-1 BEC Apparatus

The main point of this experiment is to build a vacuum chamber system attach all the instrumentation

needed (Vacuum pump deposition meter and voltmeter) and use it to apply AR coating to a laser diode

After we have accomplished the AR coating other team will be in charge of designing the BEC apparatus

and use the results of our research

78

42 Experimentrsquos Equipment

421 Vacuum Chamber

For this research we designed a vacuum chamber whose main body is shown in figure 4-2 Its

dimensions are

Width 240 mm

Length 240 mm

Height 200 mm

Outer Diameter 4 in

Inner Diameter 15 in

Fig 4-2 Vacuum Chamber Main Body

The chamber is made up of 6 pass ways pass way A is the connection with the Laser Deposition

Equipment pass way B is the connection with the Turbo Pump and pass way C is for the connection with

the Deposition Source

A

C

B

79

Pass way C is for the deposition source as mentioned above This is a system where a thermal

resistance is heated by passing a high current through it which heats up a filament boat (made of tungsten)

where the material to be evaporated is place We control the temperature as such that the material will

evaporate and the heat will not cause the filament boat to crack

Because P = Isup2 R (where P is power I is current and R is resistance) to avoid the current to flow

where it is not desired we decided that the material for the Thermocouple shown in figure 4-3 should be

Copper ᴓ 63 mm We choose it that way because Copper has very good heat dissipation characteristics

and the resistance value is low It can reduce the value of the current enough to make the thermocouple to

create heat

Fig 4-3 Thermocouple

To the thermocouple we attach the tungsten filament boat We need to take notice of materials to be

used in this design because when using high current the tungsten filament boar will heat up and so the

material must be able to keep up with the heating potential of tungsten and has a low coefficient of heat

dissipation to avoid the tungsten to fail when heating up and therefore not evaporating Considering all

this we decide to use Stainless Steel

Because this clamp will be assembled inside the chamber after many revisions it was determined it

will have the shape shown in figure 4-4

Fig 4-4 Filament Boat Clamp Design

80

For the tungsten filament boat we bought the product from a distributor The dimensions are

Length 100 mm

Width 10 mm

Height 1 mm

Our thermocouple is 15 in but the pass way C is 4 in so we need to attach a Flange that connects

15in to 4in Because these specifications are quite difficult to achieve by Milling we had to use

electrical wire cutting

For the laser clamping system where the laser that is going to be AR coated will be placed will be

connected to pass way A the assembly is shown in figure 4-5 below

Fig 4-5 Cover Assembly

For this design we used an O-ring instead of a gasket so as to save time The design of the assembly

where the laser will be placed is shown in figure 4-6

Fig 4-6 Upper Cover Inner Assembly

D

E

F

81

Point D is the plate in the assembly where the laser diode will be fixed Because of the easy

processing we decide to use Aluminum and it is screwed to the top cover Point E is the connection for

the Quartz crystal resonator and it is designed in the same as point F in this way the results of the quartz

microbalance system will be more accurate in real time Point F is the final resting place for the laser

diode We use a Thor Labs Base with dimensions of ᴓ 9mm and ᴓ 56mm for two different size laser

diodes It just needs to be plugged in for easy installation

From figure 4-6 we know that the system needs signal system connections and because of the

change in temperature inside the chamber this could affect the functioning of the quartz microbalance so

we also need to install water tubes for cooling This is shown in figure 4-7 below

Fig 4-7 Diagram of Upper Cover Connections

In figure 4-8 we show the Feed through connections and their functions

Fig 4-8 Feed through Diagram

82

1 SQM-160 wire 5 Laser Connection 1 (Vin)

2 SQM-160 (G) 6 Laser Connection 2 (G)

3 K-Type-1 7 Laser Connection 3 (PD)

4 K-Type-2 8 Not In Use

The fully assembled chamber is shown in figure 4-9

Fig 4-9 Fully Assembled Chamber

422 Quartz Crystal Microbalance

For measuring the deposition on our target for coating we used the Inficon SQM-160 RateThickness

Monitor It is an easy to use instrument for measuring many types of thin-film coatings as shown in

figure 4-10

(a) Front Panel (b) Back Panel

Fig 4-10 Inficon SQM-160

83

Table 4-1 shows the technical specifications for this equipment

Number of sensors 2 Standard 4 additional optional

Sensor Frequency Range 40 MHz ~ 60 MHz

Reference Frequency Accuracy 002

Thickness Display Resolution 1 Aring

Thickness Resolution 015 Aring (Std) 0037 Aring (Hi Res)

Density of Stored Films 05-9999 gmcc

Tooling 10-399

Z-Factor 010-1000

Final Thickness 0000-9999k Aring

Measurement Period 15 to 2 sec

Simulation Mode Yes

Frequency Mode Yes

Rate Resolution 011 Arings

Dual Crystal Yes

Etch Mode Yes

Crystal Tooling 10-399

Crystal Fail Min Max 40 to 60 MHz 41 to 61 MHz

Power 100-120 200-240~plusmn10 nominal 20W

Operation Environment 0degC ~ 50degC

0 ~ 80 RH non-condensing

0 ~ 2000 meters

Class 1 Equipment

Pollution Degree 2

Rack Dimensions 885mm x 2127mm x 1969mm

Weight 27 kg

Table 4-1 Inficon SQM-160 RateThickness Monitor Specs

84

To the SQM-160 we need to connect an Oscillator We use the Sigma Instruments Remote Oscillator

Ser No 2 268 as shown in figure 4-11

Fig 4-11 Sigma Instruments Remote Oscillator

The connections diagram is shown in figure 4-12

Fig 4-12 SQM-160 Connections Diagram

85

423 Turbo Pump

For our experiments we used the Pfeiffer TCP 015 Electronic Drive Unit shown below in figure 4-13

Table 4-2 shows the technical specifications for this equipment

(a) Front Panel (b) Back Panel

Fig 4-13 Pfeiffer TCP 015 Electronic Drive

Connection Voltage (100V) 90-112

Mains Frequency 5060 Hz

Start-up Current 22 A

Nominal Frequency 1500 Hz

Rotation Speed 10V = 1500Hz plusmn2

Analog Output Current 10 V = 25 A plusmn 5

Rotation Speed Switchpoint 750 Hz

Works Setting 8 min

Permissible Ambient Temperature 0degC ~ 40degC

Dimensions Front Panel 1285mm x 1063mm

Insertion Length 227mm

Weight 27 Kg

Table 4-2 Pfeiffer TCP 015 Electronic Drive Specs

86

The connections diagram is shown in figure 4-14

Fig 4-14Connections Diagram for Pfeiffer TCP 015

To measure the pressure inside the chamber we use the Granville Phillips 375 Convectron Vacuum

Pressure Controller shown in figure 4-15

(a) Front Panel (b) Back Panel

Fig 4-15 Granville Phillips 375 Convectron

87

Its dimensions are shown in figure 4-16

Fig 4-16 Dimensions of Convectron

Table 4-3 shows the technical specifications for this equipment

Table 4-3 Granville Phillips 375 Convectron Vacuum Pressure Controller Specs

88

424 Multimeter

For our experiment we used the Keithley 2000 Digital Multimeter as shown in figure 4-17

(a) Front Panel (b) Back Panel

Fig 4-17 Keithley Model 2000 6-12-Digit Digital Multimeter

Its technical specifications are shown in table 4-4

Table 4-4 Keithley Model 2000 6-12-Digit Digital Multimeter Specs

89

43 Experiment Procedure

1 Connecting together the equipment and the chamber

(1) We first connect the resonator to the thickness monitor and connect the other side to the

chamber

(2) We now connect the flexible tubes to the turbo pump on one side and to the chamber on the

other

(3) We need to check that tubes are tightly connected to avoid any leaks in the vacuum pumping

process which will not allow us to get to our goal of Torr As shown in figure 4-18

(4) Connect the convectron to the system as shown in figure 4-19

Fig 4-18 checking for leaks using alcohol

Fig 4-19 Convectron attached to System

90

(5) Attach the clamps of the Multimeter to the bottom of the chamber as shown in figure 4-20

(6) Place the Quartz crystal in place

(7) Close tight vacuum chamber

(8) Connect all electrical appliances to power source

Fig 4-20 Multimeter Connections

2 Starting up the System

(1) We turn on all the devices as such Check all systems are ready to function Reset all values

that might be left over from previous tests

(2) Start the thickness monitor and set all values for this experiment In our case we got to testing

the system but not actual coating So we used the simulation mode of the thickness monitor as

shown in figure 4-21

Fig 4-21 Simulation Mode

91

(3) Start the turbo pump Make sure the lid on the vacuum chamber is tightly closed

(4) Start convectron and record initial pressure

(5) Start Multimeter and record initial current

3 Coating Process

(1) If we have the deposition material inside the filament boat the power source for the high

current must be started as well

(2) Record all initial values for thickness current pressure

(3) For an ideal experiment we need a thickness of around 101 nm a pressure of Torr and

a current of 300 A

44 Results

From previous experiments we have shown that we can turn a LED into a laser by means of AR

Coating In figure 4-22 shown below we can compare the actual results of a Diode before and after AR

coating From the blue line we can see that when the diode is at a current of 15mA its light will change

from LED to laser and if we look at the red line its critical current is around 30 to 35 mA

Fig 4-22 AR Coating Comparison for Laser Diodes

This means that the light emitted is not as strong as if the diode had been coated because inside the

chamber there must be some excitation first so the reflectivity of both sides inside the diode must be high

So because of the coating in one of the sides we have opened a door and let the light come out so the

critical current is risen as such and will be higher value than that of before the coating

92

In the following figures we can see the difference between before and after coating in a material The

thickness is around 1016 nm for this material

Fig 4-23 Before Coating

Fig 4-24 After Coating

93

Chapter 5 CONCLUSIONS AND RECOMMENDATIONS

51 Conclusions

For the first part of this independent study taking into consideration the data that came out of our

research and that sent by the provider we can say

1 SUM 23 after heat treatment will unexpectedly develop cracking in the middle of the tensile

testing process and suddenly break

2 Itrsquos possible that in the process of heat treatment to the SUM 23 material the treatment was not

uniform and this will create a pre-loaded moment force on one side that pushes on the other side

of the specimen resulting in material deformation

3 In the process of attaching the strain gauges to the materials it is very easy to make errors due to

poor adhesion or sudden removal in the tensile testing process

For our second part of the independent study the following can be made

1 At the beginning of this independent study we had no idea what Bose-Einstein Condensate was

or what was its purpose After much literature we finally comprehended the basic principles to

put into practice for our research

2 Our systemrsquos basic working principles and equipmentrsquos complexity are a little difficult to grasp

but hopefully we were able to understand enough of it

3 Theoretically from relation between the power and current we can know the advantages and

disadvantages of AR Coating

4 We were able to assemble the system and run test on its functions Even though we were able to

do this there is still much more work left to do with this system

52 Recommendations

For the Tensile Testing the following can be said

1 Ask the provider to check on the process of heat treatment on the SUM 23 material and give

them the information we have gathered through our test so they can correct for the mechanical

properties found if any change is needed

2 To avoid the problem of the inaccuracy of the poor adhesion of strain gauges we can attach

multiple strain gauges to the same one specimen so as to correlate data and improve our results

For the AR Coating the following can be said

1 We need to make sure that there are no physical defects on the main body of the chamber so as to

achieve maximum efficiency in the vacuum process If there was then the vacuum will arrive to

certain point and then start to decrease

2 It would be preferable to add some sort of visual aid that will allow the user to check the inside of

the chamber without actually opening it This will help us determine at what times we should

manipulate the current to better evaporate the substrate

94

REFERENCES

[1] A L Window Strain Gauge Technology Elsevier Applied Science London and New York 2nd

Edition 1992

[2] CC Perry and HR Lissner Strain Gauge Primer McGraw-Hill Book Co Inc New York 1955

[3] James W Dally William F Riley McGraw-Hill 1978

[4] University of Colorado Boulder BEC - What is it and where did the idea come from

httpwwwcoloradoeduphysics2000becwhat_is_ithtml

[5] Ultraslow Light amp Bose-Einstein Condensates Two-way Control with Coherent Light amp Atom

Fields Harvard Hau Lab Dr Lene Vestergaard Hau Optics amp Photonics News 16 1995

[6] The Art of Taming Light Ultra-slow and Stopped Light Harvard Hau Lab Dr Lene

Vestergaard Hau Europhysics News 2004

[7] Nonlinear Optics Shocking Superfluids Harvard Hau Lab Dr Lene Vestergaard Hau Nature

Physics 2007

[8] Model P3 Strain Indicator and Recorder Instruction Manual Vishay Micro-Measurements 2005

[9] Granville-Phillips Series 375 Convectron Vacuum Gauge Controller Instruction Manual Brooks

Automation 2008

[10] Effect of Film Thickness on the Validity of the Sauerbrey Equation for Hydrated Polyelectrolyte

Films Vogt Lin Wu White 2004

[11] Quartz Crystal Microbalance Study of DNA Immobilization and Hybridization for DNA Sensor

Development Chang Zhao 2008

[12] Installation of Strain Gages with SR-4 PrecoatAdhesive Vishay Micro-Measurements 2005

[13] Strain Gauge Measurement ndash A Tutorial National Instruments 1998

[14] Correlation between Vickers Hardness Number and Yield Stress of Cold-Formed Products

Yavuz Tekkaya

[15] httpsenwikipediaorg

Page 62: PC Hinge Materials Testing and AR Laser Diode Coating

62

(c)

(d)

Fig 3-16 Cut-Off Area of (a) 1 Round Bar (b) 2 Round Bar (c) 3 Round Bar and (d) 4 Round

Bar

63

SUM 23 Black Surface Round Bar

Fig 3-17 SUM 23 Black Surface Material

Number 1 2 3

Hardness(HRB) 51 50 51

Yield Stress (MPa) 378 371 369

Tensile Strength (MPa) 467 465 464

Poissonrsquos Ratio 03 016 04

Youngrsquos Modulus (GPa) 215 266 266

Cut-off Area Shrinking () 986 94 848

Elongation () 748 805 761

Table 3-7 Mechanical Properties of SUM 23 Black Surface Material

64

Stress-Strain Diagram

(a)

(b)

65

(c)

Fig 3-18 Stress-Strain Diagrams for (a) 1 Round Bar 2 Round Bar and (c) 3 Round Bar

Cut-Off Surface

(a)

66

(b)

(c)

Fig 3-19 Cut-Off Surface of (a) 1 Round Bar 2 Round Bar and (c) 3 Round Bar

67

342 SUM 43

Fig 3-20 Untreated SUM 43 Untreated Material

Number 1 5

Hardness(HRB) 76 75

Yield Stress (MPa) 572 594

Tensile Strength (MPa) 743 785

Poissonrsquos Ratio 027 029

Youngrsquos Modulus (GPa) 200 202

Cut-off Area Shrinking () 338 2944

Elongation () 857 894

Table 3-8 Mechanical Properties of SUM 43 Untreated

68

Stress-Strain Diagrams

(a)

(b)

Fig 3-21 Stress-Strain Diagrams for SUM 43 (a) 1 Round Bar and (b) 5 Round Bar

69

Cut-Off Area

(a)

(b)

Fig 3-22 Cut-Off Area of SUM 43 (a) 1 Round Bar and (b) 5 Round Bar

70

SUM 43 Nickel Round Bar

Fig 3-23 SUM 43 Nickel Material

Number 4 5

Hardness(HRB) 51 50

Yield Stress (MPa) 1580 1544

Tensile Strength (MPa) 1639 1625

Poissonrsquos Ratio 03 028

Youngrsquos Modulus (GPa) 194 201

Cut-off Area Shrinking () 1697 137

Elongation () 376 265

Table 3-9 Mechanical Properties of SUM 43 Nickel

71

Stress-Strain Diagrams

(a)

(b)

Fig 3-24 Stress-Strain Diagrams for (a) 4 Round Bar and (b) 5 Round Bar

72

Cut-Off Area

(a)

(b)

Fig 3-25 Cut-Off Area of (a) 4 Round Bar and (b) 5 Round Bar

73

SUM 43 Black Surface Material

Fig 3-26 SUM 43 Black Surface Material

Number 3 5

Hardness(HRB) 56 56

Yield Stress (MPa) 1416 1361

Tensile Strength (MPa) 1591 1402

Poissonrsquos Ratio 029 031

Youngrsquos Modulus (GPa) 200 202

Cut-off Area Shrinking () 139 124

Elongation () 24 24

Table 3-10 Mechanical Properties of SUM 43 Black Surface Material

74

Stress-Strain Diagrams

0 2 4 6 8 10 12 14

-200

0

200

400

600

800

1000

1200

1400

1600

1800

應力 (MPa)

應變()

(a)

0 2 4 6 8 10

-200

0

200

400

600

800

1000

1200

1400

1600

應力

(MPa)

位移 ()

(b)

Fig 3-27 Stress-Strain Diagrams for (a) 3 Round Bar and (b) 5 Round Bar

(Note These curves were formulated using Visual Solutions Inc VisSim Software)

75

Cut-Off Area

(a)

(b)

Fig 3-28 Cut-Off Area of (a) 3 Round Bar and (b) 5 Round Bar

76

The force value (N) was retrieved from the Universal Testing Machine

The Poissonrsquos Ratio (ε) is calculated as

ε =

the values for the Poissonrsquos Ratio are in average around 0297

The Youngrsquos Modulus (E) is calculated as

E =

Where

Stress =

Cross-sectional Area =

where D is the Diameter

The value for D was in average around 1258 mm

The values shown by the computer because there is Slippage phenomena between the Clamp and the

specimen will not be taken into consideration for the elongation strain and Youngrsquos modulus and we will

refer to the values that we have meticulously calculated

77

Chapter 4 AR COATING IN DEPTH

41 Experimentrsquos Purpose and Principles

By means of a vacuum chamber and several other instruments we intend to apply Anti-Reflective

Coating using deposition process to a laser diode and in this way reduce its refraction so as to make it

lose less light in the process of amplification and we can control certain wavelengths we want produced

for certain desired applications in our case we are attempting to re-create a Bose-Einstein Condensate

An optimal BEC apparatus is shown in figure 4-1

Fig 4-1 BEC Apparatus

The main point of this experiment is to build a vacuum chamber system attach all the instrumentation

needed (Vacuum pump deposition meter and voltmeter) and use it to apply AR coating to a laser diode

After we have accomplished the AR coating other team will be in charge of designing the BEC apparatus

and use the results of our research

78

42 Experimentrsquos Equipment

421 Vacuum Chamber

For this research we designed a vacuum chamber whose main body is shown in figure 4-2 Its

dimensions are

Width 240 mm

Length 240 mm

Height 200 mm

Outer Diameter 4 in

Inner Diameter 15 in

Fig 4-2 Vacuum Chamber Main Body

The chamber is made up of 6 pass ways pass way A is the connection with the Laser Deposition

Equipment pass way B is the connection with the Turbo Pump and pass way C is for the connection with

the Deposition Source

A

C

B

79

Pass way C is for the deposition source as mentioned above This is a system where a thermal

resistance is heated by passing a high current through it which heats up a filament boat (made of tungsten)

where the material to be evaporated is place We control the temperature as such that the material will

evaporate and the heat will not cause the filament boat to crack

Because P = Isup2 R (where P is power I is current and R is resistance) to avoid the current to flow

where it is not desired we decided that the material for the Thermocouple shown in figure 4-3 should be

Copper ᴓ 63 mm We choose it that way because Copper has very good heat dissipation characteristics

and the resistance value is low It can reduce the value of the current enough to make the thermocouple to

create heat

Fig 4-3 Thermocouple

To the thermocouple we attach the tungsten filament boat We need to take notice of materials to be

used in this design because when using high current the tungsten filament boar will heat up and so the

material must be able to keep up with the heating potential of tungsten and has a low coefficient of heat

dissipation to avoid the tungsten to fail when heating up and therefore not evaporating Considering all

this we decide to use Stainless Steel

Because this clamp will be assembled inside the chamber after many revisions it was determined it

will have the shape shown in figure 4-4

Fig 4-4 Filament Boat Clamp Design

80

For the tungsten filament boat we bought the product from a distributor The dimensions are

Length 100 mm

Width 10 mm

Height 1 mm

Our thermocouple is 15 in but the pass way C is 4 in so we need to attach a Flange that connects

15in to 4in Because these specifications are quite difficult to achieve by Milling we had to use

electrical wire cutting

For the laser clamping system where the laser that is going to be AR coated will be placed will be

connected to pass way A the assembly is shown in figure 4-5 below

Fig 4-5 Cover Assembly

For this design we used an O-ring instead of a gasket so as to save time The design of the assembly

where the laser will be placed is shown in figure 4-6

Fig 4-6 Upper Cover Inner Assembly

D

E

F

81

Point D is the plate in the assembly where the laser diode will be fixed Because of the easy

processing we decide to use Aluminum and it is screwed to the top cover Point E is the connection for

the Quartz crystal resonator and it is designed in the same as point F in this way the results of the quartz

microbalance system will be more accurate in real time Point F is the final resting place for the laser

diode We use a Thor Labs Base with dimensions of ᴓ 9mm and ᴓ 56mm for two different size laser

diodes It just needs to be plugged in for easy installation

From figure 4-6 we know that the system needs signal system connections and because of the

change in temperature inside the chamber this could affect the functioning of the quartz microbalance so

we also need to install water tubes for cooling This is shown in figure 4-7 below

Fig 4-7 Diagram of Upper Cover Connections

In figure 4-8 we show the Feed through connections and their functions

Fig 4-8 Feed through Diagram

82

1 SQM-160 wire 5 Laser Connection 1 (Vin)

2 SQM-160 (G) 6 Laser Connection 2 (G)

3 K-Type-1 7 Laser Connection 3 (PD)

4 K-Type-2 8 Not In Use

The fully assembled chamber is shown in figure 4-9

Fig 4-9 Fully Assembled Chamber

422 Quartz Crystal Microbalance

For measuring the deposition on our target for coating we used the Inficon SQM-160 RateThickness

Monitor It is an easy to use instrument for measuring many types of thin-film coatings as shown in

figure 4-10

(a) Front Panel (b) Back Panel

Fig 4-10 Inficon SQM-160

83

Table 4-1 shows the technical specifications for this equipment

Number of sensors 2 Standard 4 additional optional

Sensor Frequency Range 40 MHz ~ 60 MHz

Reference Frequency Accuracy 002

Thickness Display Resolution 1 Aring

Thickness Resolution 015 Aring (Std) 0037 Aring (Hi Res)

Density of Stored Films 05-9999 gmcc

Tooling 10-399

Z-Factor 010-1000

Final Thickness 0000-9999k Aring

Measurement Period 15 to 2 sec

Simulation Mode Yes

Frequency Mode Yes

Rate Resolution 011 Arings

Dual Crystal Yes

Etch Mode Yes

Crystal Tooling 10-399

Crystal Fail Min Max 40 to 60 MHz 41 to 61 MHz

Power 100-120 200-240~plusmn10 nominal 20W

Operation Environment 0degC ~ 50degC

0 ~ 80 RH non-condensing

0 ~ 2000 meters

Class 1 Equipment

Pollution Degree 2

Rack Dimensions 885mm x 2127mm x 1969mm

Weight 27 kg

Table 4-1 Inficon SQM-160 RateThickness Monitor Specs

84

To the SQM-160 we need to connect an Oscillator We use the Sigma Instruments Remote Oscillator

Ser No 2 268 as shown in figure 4-11

Fig 4-11 Sigma Instruments Remote Oscillator

The connections diagram is shown in figure 4-12

Fig 4-12 SQM-160 Connections Diagram

85

423 Turbo Pump

For our experiments we used the Pfeiffer TCP 015 Electronic Drive Unit shown below in figure 4-13

Table 4-2 shows the technical specifications for this equipment

(a) Front Panel (b) Back Panel

Fig 4-13 Pfeiffer TCP 015 Electronic Drive

Connection Voltage (100V) 90-112

Mains Frequency 5060 Hz

Start-up Current 22 A

Nominal Frequency 1500 Hz

Rotation Speed 10V = 1500Hz plusmn2

Analog Output Current 10 V = 25 A plusmn 5

Rotation Speed Switchpoint 750 Hz

Works Setting 8 min

Permissible Ambient Temperature 0degC ~ 40degC

Dimensions Front Panel 1285mm x 1063mm

Insertion Length 227mm

Weight 27 Kg

Table 4-2 Pfeiffer TCP 015 Electronic Drive Specs

86

The connections diagram is shown in figure 4-14

Fig 4-14Connections Diagram for Pfeiffer TCP 015

To measure the pressure inside the chamber we use the Granville Phillips 375 Convectron Vacuum

Pressure Controller shown in figure 4-15

(a) Front Panel (b) Back Panel

Fig 4-15 Granville Phillips 375 Convectron

87

Its dimensions are shown in figure 4-16

Fig 4-16 Dimensions of Convectron

Table 4-3 shows the technical specifications for this equipment

Table 4-3 Granville Phillips 375 Convectron Vacuum Pressure Controller Specs

88

424 Multimeter

For our experiment we used the Keithley 2000 Digital Multimeter as shown in figure 4-17

(a) Front Panel (b) Back Panel

Fig 4-17 Keithley Model 2000 6-12-Digit Digital Multimeter

Its technical specifications are shown in table 4-4

Table 4-4 Keithley Model 2000 6-12-Digit Digital Multimeter Specs

89

43 Experiment Procedure

1 Connecting together the equipment and the chamber

(1) We first connect the resonator to the thickness monitor and connect the other side to the

chamber

(2) We now connect the flexible tubes to the turbo pump on one side and to the chamber on the

other

(3) We need to check that tubes are tightly connected to avoid any leaks in the vacuum pumping

process which will not allow us to get to our goal of Torr As shown in figure 4-18

(4) Connect the convectron to the system as shown in figure 4-19

Fig 4-18 checking for leaks using alcohol

Fig 4-19 Convectron attached to System

90

(5) Attach the clamps of the Multimeter to the bottom of the chamber as shown in figure 4-20

(6) Place the Quartz crystal in place

(7) Close tight vacuum chamber

(8) Connect all electrical appliances to power source

Fig 4-20 Multimeter Connections

2 Starting up the System

(1) We turn on all the devices as such Check all systems are ready to function Reset all values

that might be left over from previous tests

(2) Start the thickness monitor and set all values for this experiment In our case we got to testing

the system but not actual coating So we used the simulation mode of the thickness monitor as

shown in figure 4-21

Fig 4-21 Simulation Mode

91

(3) Start the turbo pump Make sure the lid on the vacuum chamber is tightly closed

(4) Start convectron and record initial pressure

(5) Start Multimeter and record initial current

3 Coating Process

(1) If we have the deposition material inside the filament boat the power source for the high

current must be started as well

(2) Record all initial values for thickness current pressure

(3) For an ideal experiment we need a thickness of around 101 nm a pressure of Torr and

a current of 300 A

44 Results

From previous experiments we have shown that we can turn a LED into a laser by means of AR

Coating In figure 4-22 shown below we can compare the actual results of a Diode before and after AR

coating From the blue line we can see that when the diode is at a current of 15mA its light will change

from LED to laser and if we look at the red line its critical current is around 30 to 35 mA

Fig 4-22 AR Coating Comparison for Laser Diodes

This means that the light emitted is not as strong as if the diode had been coated because inside the

chamber there must be some excitation first so the reflectivity of both sides inside the diode must be high

So because of the coating in one of the sides we have opened a door and let the light come out so the

critical current is risen as such and will be higher value than that of before the coating

92

In the following figures we can see the difference between before and after coating in a material The

thickness is around 1016 nm for this material

Fig 4-23 Before Coating

Fig 4-24 After Coating

93

Chapter 5 CONCLUSIONS AND RECOMMENDATIONS

51 Conclusions

For the first part of this independent study taking into consideration the data that came out of our

research and that sent by the provider we can say

1 SUM 23 after heat treatment will unexpectedly develop cracking in the middle of the tensile

testing process and suddenly break

2 Itrsquos possible that in the process of heat treatment to the SUM 23 material the treatment was not

uniform and this will create a pre-loaded moment force on one side that pushes on the other side

of the specimen resulting in material deformation

3 In the process of attaching the strain gauges to the materials it is very easy to make errors due to

poor adhesion or sudden removal in the tensile testing process

For our second part of the independent study the following can be made

1 At the beginning of this independent study we had no idea what Bose-Einstein Condensate was

or what was its purpose After much literature we finally comprehended the basic principles to

put into practice for our research

2 Our systemrsquos basic working principles and equipmentrsquos complexity are a little difficult to grasp

but hopefully we were able to understand enough of it

3 Theoretically from relation between the power and current we can know the advantages and

disadvantages of AR Coating

4 We were able to assemble the system and run test on its functions Even though we were able to

do this there is still much more work left to do with this system

52 Recommendations

For the Tensile Testing the following can be said

1 Ask the provider to check on the process of heat treatment on the SUM 23 material and give

them the information we have gathered through our test so they can correct for the mechanical

properties found if any change is needed

2 To avoid the problem of the inaccuracy of the poor adhesion of strain gauges we can attach

multiple strain gauges to the same one specimen so as to correlate data and improve our results

For the AR Coating the following can be said

1 We need to make sure that there are no physical defects on the main body of the chamber so as to

achieve maximum efficiency in the vacuum process If there was then the vacuum will arrive to

certain point and then start to decrease

2 It would be preferable to add some sort of visual aid that will allow the user to check the inside of

the chamber without actually opening it This will help us determine at what times we should

manipulate the current to better evaporate the substrate

94

REFERENCES

[1] A L Window Strain Gauge Technology Elsevier Applied Science London and New York 2nd

Edition 1992

[2] CC Perry and HR Lissner Strain Gauge Primer McGraw-Hill Book Co Inc New York 1955

[3] James W Dally William F Riley McGraw-Hill 1978

[4] University of Colorado Boulder BEC - What is it and where did the idea come from

httpwwwcoloradoeduphysics2000becwhat_is_ithtml

[5] Ultraslow Light amp Bose-Einstein Condensates Two-way Control with Coherent Light amp Atom

Fields Harvard Hau Lab Dr Lene Vestergaard Hau Optics amp Photonics News 16 1995

[6] The Art of Taming Light Ultra-slow and Stopped Light Harvard Hau Lab Dr Lene

Vestergaard Hau Europhysics News 2004

[7] Nonlinear Optics Shocking Superfluids Harvard Hau Lab Dr Lene Vestergaard Hau Nature

Physics 2007

[8] Model P3 Strain Indicator and Recorder Instruction Manual Vishay Micro-Measurements 2005

[9] Granville-Phillips Series 375 Convectron Vacuum Gauge Controller Instruction Manual Brooks

Automation 2008

[10] Effect of Film Thickness on the Validity of the Sauerbrey Equation for Hydrated Polyelectrolyte

Films Vogt Lin Wu White 2004

[11] Quartz Crystal Microbalance Study of DNA Immobilization and Hybridization for DNA Sensor

Development Chang Zhao 2008

[12] Installation of Strain Gages with SR-4 PrecoatAdhesive Vishay Micro-Measurements 2005

[13] Strain Gauge Measurement ndash A Tutorial National Instruments 1998

[14] Correlation between Vickers Hardness Number and Yield Stress of Cold-Formed Products

Yavuz Tekkaya

[15] httpsenwikipediaorg

Page 63: PC Hinge Materials Testing and AR Laser Diode Coating

63

SUM 23 Black Surface Round Bar

Fig 3-17 SUM 23 Black Surface Material

Number 1 2 3

Hardness(HRB) 51 50 51

Yield Stress (MPa) 378 371 369

Tensile Strength (MPa) 467 465 464

Poissonrsquos Ratio 03 016 04

Youngrsquos Modulus (GPa) 215 266 266

Cut-off Area Shrinking () 986 94 848

Elongation () 748 805 761

Table 3-7 Mechanical Properties of SUM 23 Black Surface Material

64

Stress-Strain Diagram

(a)

(b)

65

(c)

Fig 3-18 Stress-Strain Diagrams for (a) 1 Round Bar 2 Round Bar and (c) 3 Round Bar

Cut-Off Surface

(a)

66

(b)

(c)

Fig 3-19 Cut-Off Surface of (a) 1 Round Bar 2 Round Bar and (c) 3 Round Bar

67

342 SUM 43

Fig 3-20 Untreated SUM 43 Untreated Material

Number 1 5

Hardness(HRB) 76 75

Yield Stress (MPa) 572 594

Tensile Strength (MPa) 743 785

Poissonrsquos Ratio 027 029

Youngrsquos Modulus (GPa) 200 202

Cut-off Area Shrinking () 338 2944

Elongation () 857 894

Table 3-8 Mechanical Properties of SUM 43 Untreated

68

Stress-Strain Diagrams

(a)

(b)

Fig 3-21 Stress-Strain Diagrams for SUM 43 (a) 1 Round Bar and (b) 5 Round Bar

69

Cut-Off Area

(a)

(b)

Fig 3-22 Cut-Off Area of SUM 43 (a) 1 Round Bar and (b) 5 Round Bar

70

SUM 43 Nickel Round Bar

Fig 3-23 SUM 43 Nickel Material

Number 4 5

Hardness(HRB) 51 50

Yield Stress (MPa) 1580 1544

Tensile Strength (MPa) 1639 1625

Poissonrsquos Ratio 03 028

Youngrsquos Modulus (GPa) 194 201

Cut-off Area Shrinking () 1697 137

Elongation () 376 265

Table 3-9 Mechanical Properties of SUM 43 Nickel

71

Stress-Strain Diagrams

(a)

(b)

Fig 3-24 Stress-Strain Diagrams for (a) 4 Round Bar and (b) 5 Round Bar

72

Cut-Off Area

(a)

(b)

Fig 3-25 Cut-Off Area of (a) 4 Round Bar and (b) 5 Round Bar

73

SUM 43 Black Surface Material

Fig 3-26 SUM 43 Black Surface Material

Number 3 5

Hardness(HRB) 56 56

Yield Stress (MPa) 1416 1361

Tensile Strength (MPa) 1591 1402

Poissonrsquos Ratio 029 031

Youngrsquos Modulus (GPa) 200 202

Cut-off Area Shrinking () 139 124

Elongation () 24 24

Table 3-10 Mechanical Properties of SUM 43 Black Surface Material

74

Stress-Strain Diagrams

0 2 4 6 8 10 12 14

-200

0

200

400

600

800

1000

1200

1400

1600

1800

應力 (MPa)

應變()

(a)

0 2 4 6 8 10

-200

0

200

400

600

800

1000

1200

1400

1600

應力

(MPa)

位移 ()

(b)

Fig 3-27 Stress-Strain Diagrams for (a) 3 Round Bar and (b) 5 Round Bar

(Note These curves were formulated using Visual Solutions Inc VisSim Software)

75

Cut-Off Area

(a)

(b)

Fig 3-28 Cut-Off Area of (a) 3 Round Bar and (b) 5 Round Bar

76

The force value (N) was retrieved from the Universal Testing Machine

The Poissonrsquos Ratio (ε) is calculated as

ε =

the values for the Poissonrsquos Ratio are in average around 0297

The Youngrsquos Modulus (E) is calculated as

E =

Where

Stress =

Cross-sectional Area =

where D is the Diameter

The value for D was in average around 1258 mm

The values shown by the computer because there is Slippage phenomena between the Clamp and the

specimen will not be taken into consideration for the elongation strain and Youngrsquos modulus and we will

refer to the values that we have meticulously calculated

77

Chapter 4 AR COATING IN DEPTH

41 Experimentrsquos Purpose and Principles

By means of a vacuum chamber and several other instruments we intend to apply Anti-Reflective

Coating using deposition process to a laser diode and in this way reduce its refraction so as to make it

lose less light in the process of amplification and we can control certain wavelengths we want produced

for certain desired applications in our case we are attempting to re-create a Bose-Einstein Condensate

An optimal BEC apparatus is shown in figure 4-1

Fig 4-1 BEC Apparatus

The main point of this experiment is to build a vacuum chamber system attach all the instrumentation

needed (Vacuum pump deposition meter and voltmeter) and use it to apply AR coating to a laser diode

After we have accomplished the AR coating other team will be in charge of designing the BEC apparatus

and use the results of our research

78

42 Experimentrsquos Equipment

421 Vacuum Chamber

For this research we designed a vacuum chamber whose main body is shown in figure 4-2 Its

dimensions are

Width 240 mm

Length 240 mm

Height 200 mm

Outer Diameter 4 in

Inner Diameter 15 in

Fig 4-2 Vacuum Chamber Main Body

The chamber is made up of 6 pass ways pass way A is the connection with the Laser Deposition

Equipment pass way B is the connection with the Turbo Pump and pass way C is for the connection with

the Deposition Source

A

C

B

79

Pass way C is for the deposition source as mentioned above This is a system where a thermal

resistance is heated by passing a high current through it which heats up a filament boat (made of tungsten)

where the material to be evaporated is place We control the temperature as such that the material will

evaporate and the heat will not cause the filament boat to crack

Because P = Isup2 R (where P is power I is current and R is resistance) to avoid the current to flow

where it is not desired we decided that the material for the Thermocouple shown in figure 4-3 should be

Copper ᴓ 63 mm We choose it that way because Copper has very good heat dissipation characteristics

and the resistance value is low It can reduce the value of the current enough to make the thermocouple to

create heat

Fig 4-3 Thermocouple

To the thermocouple we attach the tungsten filament boat We need to take notice of materials to be

used in this design because when using high current the tungsten filament boar will heat up and so the

material must be able to keep up with the heating potential of tungsten and has a low coefficient of heat

dissipation to avoid the tungsten to fail when heating up and therefore not evaporating Considering all

this we decide to use Stainless Steel

Because this clamp will be assembled inside the chamber after many revisions it was determined it

will have the shape shown in figure 4-4

Fig 4-4 Filament Boat Clamp Design

80

For the tungsten filament boat we bought the product from a distributor The dimensions are

Length 100 mm

Width 10 mm

Height 1 mm

Our thermocouple is 15 in but the pass way C is 4 in so we need to attach a Flange that connects

15in to 4in Because these specifications are quite difficult to achieve by Milling we had to use

electrical wire cutting

For the laser clamping system where the laser that is going to be AR coated will be placed will be

connected to pass way A the assembly is shown in figure 4-5 below

Fig 4-5 Cover Assembly

For this design we used an O-ring instead of a gasket so as to save time The design of the assembly

where the laser will be placed is shown in figure 4-6

Fig 4-6 Upper Cover Inner Assembly

D

E

F

81

Point D is the plate in the assembly where the laser diode will be fixed Because of the easy

processing we decide to use Aluminum and it is screwed to the top cover Point E is the connection for

the Quartz crystal resonator and it is designed in the same as point F in this way the results of the quartz

microbalance system will be more accurate in real time Point F is the final resting place for the laser

diode We use a Thor Labs Base with dimensions of ᴓ 9mm and ᴓ 56mm for two different size laser

diodes It just needs to be plugged in for easy installation

From figure 4-6 we know that the system needs signal system connections and because of the

change in temperature inside the chamber this could affect the functioning of the quartz microbalance so

we also need to install water tubes for cooling This is shown in figure 4-7 below

Fig 4-7 Diagram of Upper Cover Connections

In figure 4-8 we show the Feed through connections and their functions

Fig 4-8 Feed through Diagram

82

1 SQM-160 wire 5 Laser Connection 1 (Vin)

2 SQM-160 (G) 6 Laser Connection 2 (G)

3 K-Type-1 7 Laser Connection 3 (PD)

4 K-Type-2 8 Not In Use

The fully assembled chamber is shown in figure 4-9

Fig 4-9 Fully Assembled Chamber

422 Quartz Crystal Microbalance

For measuring the deposition on our target for coating we used the Inficon SQM-160 RateThickness

Monitor It is an easy to use instrument for measuring many types of thin-film coatings as shown in

figure 4-10

(a) Front Panel (b) Back Panel

Fig 4-10 Inficon SQM-160

83

Table 4-1 shows the technical specifications for this equipment

Number of sensors 2 Standard 4 additional optional

Sensor Frequency Range 40 MHz ~ 60 MHz

Reference Frequency Accuracy 002

Thickness Display Resolution 1 Aring

Thickness Resolution 015 Aring (Std) 0037 Aring (Hi Res)

Density of Stored Films 05-9999 gmcc

Tooling 10-399

Z-Factor 010-1000

Final Thickness 0000-9999k Aring

Measurement Period 15 to 2 sec

Simulation Mode Yes

Frequency Mode Yes

Rate Resolution 011 Arings

Dual Crystal Yes

Etch Mode Yes

Crystal Tooling 10-399

Crystal Fail Min Max 40 to 60 MHz 41 to 61 MHz

Power 100-120 200-240~plusmn10 nominal 20W

Operation Environment 0degC ~ 50degC

0 ~ 80 RH non-condensing

0 ~ 2000 meters

Class 1 Equipment

Pollution Degree 2

Rack Dimensions 885mm x 2127mm x 1969mm

Weight 27 kg

Table 4-1 Inficon SQM-160 RateThickness Monitor Specs

84

To the SQM-160 we need to connect an Oscillator We use the Sigma Instruments Remote Oscillator

Ser No 2 268 as shown in figure 4-11

Fig 4-11 Sigma Instruments Remote Oscillator

The connections diagram is shown in figure 4-12

Fig 4-12 SQM-160 Connections Diagram

85

423 Turbo Pump

For our experiments we used the Pfeiffer TCP 015 Electronic Drive Unit shown below in figure 4-13

Table 4-2 shows the technical specifications for this equipment

(a) Front Panel (b) Back Panel

Fig 4-13 Pfeiffer TCP 015 Electronic Drive

Connection Voltage (100V) 90-112

Mains Frequency 5060 Hz

Start-up Current 22 A

Nominal Frequency 1500 Hz

Rotation Speed 10V = 1500Hz plusmn2

Analog Output Current 10 V = 25 A plusmn 5

Rotation Speed Switchpoint 750 Hz

Works Setting 8 min

Permissible Ambient Temperature 0degC ~ 40degC

Dimensions Front Panel 1285mm x 1063mm

Insertion Length 227mm

Weight 27 Kg

Table 4-2 Pfeiffer TCP 015 Electronic Drive Specs

86

The connections diagram is shown in figure 4-14

Fig 4-14Connections Diagram for Pfeiffer TCP 015

To measure the pressure inside the chamber we use the Granville Phillips 375 Convectron Vacuum

Pressure Controller shown in figure 4-15

(a) Front Panel (b) Back Panel

Fig 4-15 Granville Phillips 375 Convectron

87

Its dimensions are shown in figure 4-16

Fig 4-16 Dimensions of Convectron

Table 4-3 shows the technical specifications for this equipment

Table 4-3 Granville Phillips 375 Convectron Vacuum Pressure Controller Specs

88

424 Multimeter

For our experiment we used the Keithley 2000 Digital Multimeter as shown in figure 4-17

(a) Front Panel (b) Back Panel

Fig 4-17 Keithley Model 2000 6-12-Digit Digital Multimeter

Its technical specifications are shown in table 4-4

Table 4-4 Keithley Model 2000 6-12-Digit Digital Multimeter Specs

89

43 Experiment Procedure

1 Connecting together the equipment and the chamber

(1) We first connect the resonator to the thickness monitor and connect the other side to the

chamber

(2) We now connect the flexible tubes to the turbo pump on one side and to the chamber on the

other

(3) We need to check that tubes are tightly connected to avoid any leaks in the vacuum pumping

process which will not allow us to get to our goal of Torr As shown in figure 4-18

(4) Connect the convectron to the system as shown in figure 4-19

Fig 4-18 checking for leaks using alcohol

Fig 4-19 Convectron attached to System

90

(5) Attach the clamps of the Multimeter to the bottom of the chamber as shown in figure 4-20

(6) Place the Quartz crystal in place

(7) Close tight vacuum chamber

(8) Connect all electrical appliances to power source

Fig 4-20 Multimeter Connections

2 Starting up the System

(1) We turn on all the devices as such Check all systems are ready to function Reset all values

that might be left over from previous tests

(2) Start the thickness monitor and set all values for this experiment In our case we got to testing

the system but not actual coating So we used the simulation mode of the thickness monitor as

shown in figure 4-21

Fig 4-21 Simulation Mode

91

(3) Start the turbo pump Make sure the lid on the vacuum chamber is tightly closed

(4) Start convectron and record initial pressure

(5) Start Multimeter and record initial current

3 Coating Process

(1) If we have the deposition material inside the filament boat the power source for the high

current must be started as well

(2) Record all initial values for thickness current pressure

(3) For an ideal experiment we need a thickness of around 101 nm a pressure of Torr and

a current of 300 A

44 Results

From previous experiments we have shown that we can turn a LED into a laser by means of AR

Coating In figure 4-22 shown below we can compare the actual results of a Diode before and after AR

coating From the blue line we can see that when the diode is at a current of 15mA its light will change

from LED to laser and if we look at the red line its critical current is around 30 to 35 mA

Fig 4-22 AR Coating Comparison for Laser Diodes

This means that the light emitted is not as strong as if the diode had been coated because inside the

chamber there must be some excitation first so the reflectivity of both sides inside the diode must be high

So because of the coating in one of the sides we have opened a door and let the light come out so the

critical current is risen as such and will be higher value than that of before the coating

92

In the following figures we can see the difference between before and after coating in a material The

thickness is around 1016 nm for this material

Fig 4-23 Before Coating

Fig 4-24 After Coating

93

Chapter 5 CONCLUSIONS AND RECOMMENDATIONS

51 Conclusions

For the first part of this independent study taking into consideration the data that came out of our

research and that sent by the provider we can say

1 SUM 23 after heat treatment will unexpectedly develop cracking in the middle of the tensile

testing process and suddenly break

2 Itrsquos possible that in the process of heat treatment to the SUM 23 material the treatment was not

uniform and this will create a pre-loaded moment force on one side that pushes on the other side

of the specimen resulting in material deformation

3 In the process of attaching the strain gauges to the materials it is very easy to make errors due to

poor adhesion or sudden removal in the tensile testing process

For our second part of the independent study the following can be made

1 At the beginning of this independent study we had no idea what Bose-Einstein Condensate was

or what was its purpose After much literature we finally comprehended the basic principles to

put into practice for our research

2 Our systemrsquos basic working principles and equipmentrsquos complexity are a little difficult to grasp

but hopefully we were able to understand enough of it

3 Theoretically from relation between the power and current we can know the advantages and

disadvantages of AR Coating

4 We were able to assemble the system and run test on its functions Even though we were able to

do this there is still much more work left to do with this system

52 Recommendations

For the Tensile Testing the following can be said

1 Ask the provider to check on the process of heat treatment on the SUM 23 material and give

them the information we have gathered through our test so they can correct for the mechanical

properties found if any change is needed

2 To avoid the problem of the inaccuracy of the poor adhesion of strain gauges we can attach

multiple strain gauges to the same one specimen so as to correlate data and improve our results

For the AR Coating the following can be said

1 We need to make sure that there are no physical defects on the main body of the chamber so as to

achieve maximum efficiency in the vacuum process If there was then the vacuum will arrive to

certain point and then start to decrease

2 It would be preferable to add some sort of visual aid that will allow the user to check the inside of

the chamber without actually opening it This will help us determine at what times we should

manipulate the current to better evaporate the substrate

94

REFERENCES

[1] A L Window Strain Gauge Technology Elsevier Applied Science London and New York 2nd

Edition 1992

[2] CC Perry and HR Lissner Strain Gauge Primer McGraw-Hill Book Co Inc New York 1955

[3] James W Dally William F Riley McGraw-Hill 1978

[4] University of Colorado Boulder BEC - What is it and where did the idea come from

httpwwwcoloradoeduphysics2000becwhat_is_ithtml

[5] Ultraslow Light amp Bose-Einstein Condensates Two-way Control with Coherent Light amp Atom

Fields Harvard Hau Lab Dr Lene Vestergaard Hau Optics amp Photonics News 16 1995

[6] The Art of Taming Light Ultra-slow and Stopped Light Harvard Hau Lab Dr Lene

Vestergaard Hau Europhysics News 2004

[7] Nonlinear Optics Shocking Superfluids Harvard Hau Lab Dr Lene Vestergaard Hau Nature

Physics 2007

[8] Model P3 Strain Indicator and Recorder Instruction Manual Vishay Micro-Measurements 2005

[9] Granville-Phillips Series 375 Convectron Vacuum Gauge Controller Instruction Manual Brooks

Automation 2008

[10] Effect of Film Thickness on the Validity of the Sauerbrey Equation for Hydrated Polyelectrolyte

Films Vogt Lin Wu White 2004

[11] Quartz Crystal Microbalance Study of DNA Immobilization and Hybridization for DNA Sensor

Development Chang Zhao 2008

[12] Installation of Strain Gages with SR-4 PrecoatAdhesive Vishay Micro-Measurements 2005

[13] Strain Gauge Measurement ndash A Tutorial National Instruments 1998

[14] Correlation between Vickers Hardness Number and Yield Stress of Cold-Formed Products

Yavuz Tekkaya

[15] httpsenwikipediaorg

Page 64: PC Hinge Materials Testing and AR Laser Diode Coating

64

Stress-Strain Diagram

(a)

(b)

65

(c)

Fig 3-18 Stress-Strain Diagrams for (a) 1 Round Bar 2 Round Bar and (c) 3 Round Bar

Cut-Off Surface

(a)

66

(b)

(c)

Fig 3-19 Cut-Off Surface of (a) 1 Round Bar 2 Round Bar and (c) 3 Round Bar

67

342 SUM 43

Fig 3-20 Untreated SUM 43 Untreated Material

Number 1 5

Hardness(HRB) 76 75

Yield Stress (MPa) 572 594

Tensile Strength (MPa) 743 785

Poissonrsquos Ratio 027 029

Youngrsquos Modulus (GPa) 200 202

Cut-off Area Shrinking () 338 2944

Elongation () 857 894

Table 3-8 Mechanical Properties of SUM 43 Untreated

68

Stress-Strain Diagrams

(a)

(b)

Fig 3-21 Stress-Strain Diagrams for SUM 43 (a) 1 Round Bar and (b) 5 Round Bar

69

Cut-Off Area

(a)

(b)

Fig 3-22 Cut-Off Area of SUM 43 (a) 1 Round Bar and (b) 5 Round Bar

70

SUM 43 Nickel Round Bar

Fig 3-23 SUM 43 Nickel Material

Number 4 5

Hardness(HRB) 51 50

Yield Stress (MPa) 1580 1544

Tensile Strength (MPa) 1639 1625

Poissonrsquos Ratio 03 028

Youngrsquos Modulus (GPa) 194 201

Cut-off Area Shrinking () 1697 137

Elongation () 376 265

Table 3-9 Mechanical Properties of SUM 43 Nickel

71

Stress-Strain Diagrams

(a)

(b)

Fig 3-24 Stress-Strain Diagrams for (a) 4 Round Bar and (b) 5 Round Bar

72

Cut-Off Area

(a)

(b)

Fig 3-25 Cut-Off Area of (a) 4 Round Bar and (b) 5 Round Bar

73

SUM 43 Black Surface Material

Fig 3-26 SUM 43 Black Surface Material

Number 3 5

Hardness(HRB) 56 56

Yield Stress (MPa) 1416 1361

Tensile Strength (MPa) 1591 1402

Poissonrsquos Ratio 029 031

Youngrsquos Modulus (GPa) 200 202

Cut-off Area Shrinking () 139 124

Elongation () 24 24

Table 3-10 Mechanical Properties of SUM 43 Black Surface Material

74

Stress-Strain Diagrams

0 2 4 6 8 10 12 14

-200

0

200

400

600

800

1000

1200

1400

1600

1800

應力 (MPa)

應變()

(a)

0 2 4 6 8 10

-200

0

200

400

600

800

1000

1200

1400

1600

應力

(MPa)

位移 ()

(b)

Fig 3-27 Stress-Strain Diagrams for (a) 3 Round Bar and (b) 5 Round Bar

(Note These curves were formulated using Visual Solutions Inc VisSim Software)

75

Cut-Off Area

(a)

(b)

Fig 3-28 Cut-Off Area of (a) 3 Round Bar and (b) 5 Round Bar

76

The force value (N) was retrieved from the Universal Testing Machine

The Poissonrsquos Ratio (ε) is calculated as

ε =

the values for the Poissonrsquos Ratio are in average around 0297

The Youngrsquos Modulus (E) is calculated as

E =

Where

Stress =

Cross-sectional Area =

where D is the Diameter

The value for D was in average around 1258 mm

The values shown by the computer because there is Slippage phenomena between the Clamp and the

specimen will not be taken into consideration for the elongation strain and Youngrsquos modulus and we will

refer to the values that we have meticulously calculated

77

Chapter 4 AR COATING IN DEPTH

41 Experimentrsquos Purpose and Principles

By means of a vacuum chamber and several other instruments we intend to apply Anti-Reflective

Coating using deposition process to a laser diode and in this way reduce its refraction so as to make it

lose less light in the process of amplification and we can control certain wavelengths we want produced

for certain desired applications in our case we are attempting to re-create a Bose-Einstein Condensate

An optimal BEC apparatus is shown in figure 4-1

Fig 4-1 BEC Apparatus

The main point of this experiment is to build a vacuum chamber system attach all the instrumentation

needed (Vacuum pump deposition meter and voltmeter) and use it to apply AR coating to a laser diode

After we have accomplished the AR coating other team will be in charge of designing the BEC apparatus

and use the results of our research

78

42 Experimentrsquos Equipment

421 Vacuum Chamber

For this research we designed a vacuum chamber whose main body is shown in figure 4-2 Its

dimensions are

Width 240 mm

Length 240 mm

Height 200 mm

Outer Diameter 4 in

Inner Diameter 15 in

Fig 4-2 Vacuum Chamber Main Body

The chamber is made up of 6 pass ways pass way A is the connection with the Laser Deposition

Equipment pass way B is the connection with the Turbo Pump and pass way C is for the connection with

the Deposition Source

A

C

B

79

Pass way C is for the deposition source as mentioned above This is a system where a thermal

resistance is heated by passing a high current through it which heats up a filament boat (made of tungsten)

where the material to be evaporated is place We control the temperature as such that the material will

evaporate and the heat will not cause the filament boat to crack

Because P = Isup2 R (where P is power I is current and R is resistance) to avoid the current to flow

where it is not desired we decided that the material for the Thermocouple shown in figure 4-3 should be

Copper ᴓ 63 mm We choose it that way because Copper has very good heat dissipation characteristics

and the resistance value is low It can reduce the value of the current enough to make the thermocouple to

create heat

Fig 4-3 Thermocouple

To the thermocouple we attach the tungsten filament boat We need to take notice of materials to be

used in this design because when using high current the tungsten filament boar will heat up and so the

material must be able to keep up with the heating potential of tungsten and has a low coefficient of heat

dissipation to avoid the tungsten to fail when heating up and therefore not evaporating Considering all

this we decide to use Stainless Steel

Because this clamp will be assembled inside the chamber after many revisions it was determined it

will have the shape shown in figure 4-4

Fig 4-4 Filament Boat Clamp Design

80

For the tungsten filament boat we bought the product from a distributor The dimensions are

Length 100 mm

Width 10 mm

Height 1 mm

Our thermocouple is 15 in but the pass way C is 4 in so we need to attach a Flange that connects

15in to 4in Because these specifications are quite difficult to achieve by Milling we had to use

electrical wire cutting

For the laser clamping system where the laser that is going to be AR coated will be placed will be

connected to pass way A the assembly is shown in figure 4-5 below

Fig 4-5 Cover Assembly

For this design we used an O-ring instead of a gasket so as to save time The design of the assembly

where the laser will be placed is shown in figure 4-6

Fig 4-6 Upper Cover Inner Assembly

D

E

F

81

Point D is the plate in the assembly where the laser diode will be fixed Because of the easy

processing we decide to use Aluminum and it is screwed to the top cover Point E is the connection for

the Quartz crystal resonator and it is designed in the same as point F in this way the results of the quartz

microbalance system will be more accurate in real time Point F is the final resting place for the laser

diode We use a Thor Labs Base with dimensions of ᴓ 9mm and ᴓ 56mm for two different size laser

diodes It just needs to be plugged in for easy installation

From figure 4-6 we know that the system needs signal system connections and because of the

change in temperature inside the chamber this could affect the functioning of the quartz microbalance so

we also need to install water tubes for cooling This is shown in figure 4-7 below

Fig 4-7 Diagram of Upper Cover Connections

In figure 4-8 we show the Feed through connections and their functions

Fig 4-8 Feed through Diagram

82

1 SQM-160 wire 5 Laser Connection 1 (Vin)

2 SQM-160 (G) 6 Laser Connection 2 (G)

3 K-Type-1 7 Laser Connection 3 (PD)

4 K-Type-2 8 Not In Use

The fully assembled chamber is shown in figure 4-9

Fig 4-9 Fully Assembled Chamber

422 Quartz Crystal Microbalance

For measuring the deposition on our target for coating we used the Inficon SQM-160 RateThickness

Monitor It is an easy to use instrument for measuring many types of thin-film coatings as shown in

figure 4-10

(a) Front Panel (b) Back Panel

Fig 4-10 Inficon SQM-160

83

Table 4-1 shows the technical specifications for this equipment

Number of sensors 2 Standard 4 additional optional

Sensor Frequency Range 40 MHz ~ 60 MHz

Reference Frequency Accuracy 002

Thickness Display Resolution 1 Aring

Thickness Resolution 015 Aring (Std) 0037 Aring (Hi Res)

Density of Stored Films 05-9999 gmcc

Tooling 10-399

Z-Factor 010-1000

Final Thickness 0000-9999k Aring

Measurement Period 15 to 2 sec

Simulation Mode Yes

Frequency Mode Yes

Rate Resolution 011 Arings

Dual Crystal Yes

Etch Mode Yes

Crystal Tooling 10-399

Crystal Fail Min Max 40 to 60 MHz 41 to 61 MHz

Power 100-120 200-240~plusmn10 nominal 20W

Operation Environment 0degC ~ 50degC

0 ~ 80 RH non-condensing

0 ~ 2000 meters

Class 1 Equipment

Pollution Degree 2

Rack Dimensions 885mm x 2127mm x 1969mm

Weight 27 kg

Table 4-1 Inficon SQM-160 RateThickness Monitor Specs

84

To the SQM-160 we need to connect an Oscillator We use the Sigma Instruments Remote Oscillator

Ser No 2 268 as shown in figure 4-11

Fig 4-11 Sigma Instruments Remote Oscillator

The connections diagram is shown in figure 4-12

Fig 4-12 SQM-160 Connections Diagram

85

423 Turbo Pump

For our experiments we used the Pfeiffer TCP 015 Electronic Drive Unit shown below in figure 4-13

Table 4-2 shows the technical specifications for this equipment

(a) Front Panel (b) Back Panel

Fig 4-13 Pfeiffer TCP 015 Electronic Drive

Connection Voltage (100V) 90-112

Mains Frequency 5060 Hz

Start-up Current 22 A

Nominal Frequency 1500 Hz

Rotation Speed 10V = 1500Hz plusmn2

Analog Output Current 10 V = 25 A plusmn 5

Rotation Speed Switchpoint 750 Hz

Works Setting 8 min

Permissible Ambient Temperature 0degC ~ 40degC

Dimensions Front Panel 1285mm x 1063mm

Insertion Length 227mm

Weight 27 Kg

Table 4-2 Pfeiffer TCP 015 Electronic Drive Specs

86

The connections diagram is shown in figure 4-14

Fig 4-14Connections Diagram for Pfeiffer TCP 015

To measure the pressure inside the chamber we use the Granville Phillips 375 Convectron Vacuum

Pressure Controller shown in figure 4-15

(a) Front Panel (b) Back Panel

Fig 4-15 Granville Phillips 375 Convectron

87

Its dimensions are shown in figure 4-16

Fig 4-16 Dimensions of Convectron

Table 4-3 shows the technical specifications for this equipment

Table 4-3 Granville Phillips 375 Convectron Vacuum Pressure Controller Specs

88

424 Multimeter

For our experiment we used the Keithley 2000 Digital Multimeter as shown in figure 4-17

(a) Front Panel (b) Back Panel

Fig 4-17 Keithley Model 2000 6-12-Digit Digital Multimeter

Its technical specifications are shown in table 4-4

Table 4-4 Keithley Model 2000 6-12-Digit Digital Multimeter Specs

89

43 Experiment Procedure

1 Connecting together the equipment and the chamber

(1) We first connect the resonator to the thickness monitor and connect the other side to the

chamber

(2) We now connect the flexible tubes to the turbo pump on one side and to the chamber on the

other

(3) We need to check that tubes are tightly connected to avoid any leaks in the vacuum pumping

process which will not allow us to get to our goal of Torr As shown in figure 4-18

(4) Connect the convectron to the system as shown in figure 4-19

Fig 4-18 checking for leaks using alcohol

Fig 4-19 Convectron attached to System

90

(5) Attach the clamps of the Multimeter to the bottom of the chamber as shown in figure 4-20

(6) Place the Quartz crystal in place

(7) Close tight vacuum chamber

(8) Connect all electrical appliances to power source

Fig 4-20 Multimeter Connections

2 Starting up the System

(1) We turn on all the devices as such Check all systems are ready to function Reset all values

that might be left over from previous tests

(2) Start the thickness monitor and set all values for this experiment In our case we got to testing

the system but not actual coating So we used the simulation mode of the thickness monitor as

shown in figure 4-21

Fig 4-21 Simulation Mode

91

(3) Start the turbo pump Make sure the lid on the vacuum chamber is tightly closed

(4) Start convectron and record initial pressure

(5) Start Multimeter and record initial current

3 Coating Process

(1) If we have the deposition material inside the filament boat the power source for the high

current must be started as well

(2) Record all initial values for thickness current pressure

(3) For an ideal experiment we need a thickness of around 101 nm a pressure of Torr and

a current of 300 A

44 Results

From previous experiments we have shown that we can turn a LED into a laser by means of AR

Coating In figure 4-22 shown below we can compare the actual results of a Diode before and after AR

coating From the blue line we can see that when the diode is at a current of 15mA its light will change

from LED to laser and if we look at the red line its critical current is around 30 to 35 mA

Fig 4-22 AR Coating Comparison for Laser Diodes

This means that the light emitted is not as strong as if the diode had been coated because inside the

chamber there must be some excitation first so the reflectivity of both sides inside the diode must be high

So because of the coating in one of the sides we have opened a door and let the light come out so the

critical current is risen as such and will be higher value than that of before the coating

92

In the following figures we can see the difference between before and after coating in a material The

thickness is around 1016 nm for this material

Fig 4-23 Before Coating

Fig 4-24 After Coating

93

Chapter 5 CONCLUSIONS AND RECOMMENDATIONS

51 Conclusions

For the first part of this independent study taking into consideration the data that came out of our

research and that sent by the provider we can say

1 SUM 23 after heat treatment will unexpectedly develop cracking in the middle of the tensile

testing process and suddenly break

2 Itrsquos possible that in the process of heat treatment to the SUM 23 material the treatment was not

uniform and this will create a pre-loaded moment force on one side that pushes on the other side

of the specimen resulting in material deformation

3 In the process of attaching the strain gauges to the materials it is very easy to make errors due to

poor adhesion or sudden removal in the tensile testing process

For our second part of the independent study the following can be made

1 At the beginning of this independent study we had no idea what Bose-Einstein Condensate was

or what was its purpose After much literature we finally comprehended the basic principles to

put into practice for our research

2 Our systemrsquos basic working principles and equipmentrsquos complexity are a little difficult to grasp

but hopefully we were able to understand enough of it

3 Theoretically from relation between the power and current we can know the advantages and

disadvantages of AR Coating

4 We were able to assemble the system and run test on its functions Even though we were able to

do this there is still much more work left to do with this system

52 Recommendations

For the Tensile Testing the following can be said

1 Ask the provider to check on the process of heat treatment on the SUM 23 material and give

them the information we have gathered through our test so they can correct for the mechanical

properties found if any change is needed

2 To avoid the problem of the inaccuracy of the poor adhesion of strain gauges we can attach

multiple strain gauges to the same one specimen so as to correlate data and improve our results

For the AR Coating the following can be said

1 We need to make sure that there are no physical defects on the main body of the chamber so as to

achieve maximum efficiency in the vacuum process If there was then the vacuum will arrive to

certain point and then start to decrease

2 It would be preferable to add some sort of visual aid that will allow the user to check the inside of

the chamber without actually opening it This will help us determine at what times we should

manipulate the current to better evaporate the substrate

94

REFERENCES

[1] A L Window Strain Gauge Technology Elsevier Applied Science London and New York 2nd

Edition 1992

[2] CC Perry and HR Lissner Strain Gauge Primer McGraw-Hill Book Co Inc New York 1955

[3] James W Dally William F Riley McGraw-Hill 1978

[4] University of Colorado Boulder BEC - What is it and where did the idea come from

httpwwwcoloradoeduphysics2000becwhat_is_ithtml

[5] Ultraslow Light amp Bose-Einstein Condensates Two-way Control with Coherent Light amp Atom

Fields Harvard Hau Lab Dr Lene Vestergaard Hau Optics amp Photonics News 16 1995

[6] The Art of Taming Light Ultra-slow and Stopped Light Harvard Hau Lab Dr Lene

Vestergaard Hau Europhysics News 2004

[7] Nonlinear Optics Shocking Superfluids Harvard Hau Lab Dr Lene Vestergaard Hau Nature

Physics 2007

[8] Model P3 Strain Indicator and Recorder Instruction Manual Vishay Micro-Measurements 2005

[9] Granville-Phillips Series 375 Convectron Vacuum Gauge Controller Instruction Manual Brooks

Automation 2008

[10] Effect of Film Thickness on the Validity of the Sauerbrey Equation for Hydrated Polyelectrolyte

Films Vogt Lin Wu White 2004

[11] Quartz Crystal Microbalance Study of DNA Immobilization and Hybridization for DNA Sensor

Development Chang Zhao 2008

[12] Installation of Strain Gages with SR-4 PrecoatAdhesive Vishay Micro-Measurements 2005

[13] Strain Gauge Measurement ndash A Tutorial National Instruments 1998

[14] Correlation between Vickers Hardness Number and Yield Stress of Cold-Formed Products

Yavuz Tekkaya

[15] httpsenwikipediaorg

Page 65: PC Hinge Materials Testing and AR Laser Diode Coating

65

(c)

Fig 3-18 Stress-Strain Diagrams for (a) 1 Round Bar 2 Round Bar and (c) 3 Round Bar

Cut-Off Surface

(a)

66

(b)

(c)

Fig 3-19 Cut-Off Surface of (a) 1 Round Bar 2 Round Bar and (c) 3 Round Bar

67

342 SUM 43

Fig 3-20 Untreated SUM 43 Untreated Material

Number 1 5

Hardness(HRB) 76 75

Yield Stress (MPa) 572 594

Tensile Strength (MPa) 743 785

Poissonrsquos Ratio 027 029

Youngrsquos Modulus (GPa) 200 202

Cut-off Area Shrinking () 338 2944

Elongation () 857 894

Table 3-8 Mechanical Properties of SUM 43 Untreated

68

Stress-Strain Diagrams

(a)

(b)

Fig 3-21 Stress-Strain Diagrams for SUM 43 (a) 1 Round Bar and (b) 5 Round Bar

69

Cut-Off Area

(a)

(b)

Fig 3-22 Cut-Off Area of SUM 43 (a) 1 Round Bar and (b) 5 Round Bar

70

SUM 43 Nickel Round Bar

Fig 3-23 SUM 43 Nickel Material

Number 4 5

Hardness(HRB) 51 50

Yield Stress (MPa) 1580 1544

Tensile Strength (MPa) 1639 1625

Poissonrsquos Ratio 03 028

Youngrsquos Modulus (GPa) 194 201

Cut-off Area Shrinking () 1697 137

Elongation () 376 265

Table 3-9 Mechanical Properties of SUM 43 Nickel

71

Stress-Strain Diagrams

(a)

(b)

Fig 3-24 Stress-Strain Diagrams for (a) 4 Round Bar and (b) 5 Round Bar

72

Cut-Off Area

(a)

(b)

Fig 3-25 Cut-Off Area of (a) 4 Round Bar and (b) 5 Round Bar

73

SUM 43 Black Surface Material

Fig 3-26 SUM 43 Black Surface Material

Number 3 5

Hardness(HRB) 56 56

Yield Stress (MPa) 1416 1361

Tensile Strength (MPa) 1591 1402

Poissonrsquos Ratio 029 031

Youngrsquos Modulus (GPa) 200 202

Cut-off Area Shrinking () 139 124

Elongation () 24 24

Table 3-10 Mechanical Properties of SUM 43 Black Surface Material

74

Stress-Strain Diagrams

0 2 4 6 8 10 12 14

-200

0

200

400

600

800

1000

1200

1400

1600

1800

應力 (MPa)

應變()

(a)

0 2 4 6 8 10

-200

0

200

400

600

800

1000

1200

1400

1600

應力

(MPa)

位移 ()

(b)

Fig 3-27 Stress-Strain Diagrams for (a) 3 Round Bar and (b) 5 Round Bar

(Note These curves were formulated using Visual Solutions Inc VisSim Software)

75

Cut-Off Area

(a)

(b)

Fig 3-28 Cut-Off Area of (a) 3 Round Bar and (b) 5 Round Bar

76

The force value (N) was retrieved from the Universal Testing Machine

The Poissonrsquos Ratio (ε) is calculated as

ε =

the values for the Poissonrsquos Ratio are in average around 0297

The Youngrsquos Modulus (E) is calculated as

E =

Where

Stress =

Cross-sectional Area =

where D is the Diameter

The value for D was in average around 1258 mm

The values shown by the computer because there is Slippage phenomena between the Clamp and the

specimen will not be taken into consideration for the elongation strain and Youngrsquos modulus and we will

refer to the values that we have meticulously calculated

77

Chapter 4 AR COATING IN DEPTH

41 Experimentrsquos Purpose and Principles

By means of a vacuum chamber and several other instruments we intend to apply Anti-Reflective

Coating using deposition process to a laser diode and in this way reduce its refraction so as to make it

lose less light in the process of amplification and we can control certain wavelengths we want produced

for certain desired applications in our case we are attempting to re-create a Bose-Einstein Condensate

An optimal BEC apparatus is shown in figure 4-1

Fig 4-1 BEC Apparatus

The main point of this experiment is to build a vacuum chamber system attach all the instrumentation

needed (Vacuum pump deposition meter and voltmeter) and use it to apply AR coating to a laser diode

After we have accomplished the AR coating other team will be in charge of designing the BEC apparatus

and use the results of our research

78

42 Experimentrsquos Equipment

421 Vacuum Chamber

For this research we designed a vacuum chamber whose main body is shown in figure 4-2 Its

dimensions are

Width 240 mm

Length 240 mm

Height 200 mm

Outer Diameter 4 in

Inner Diameter 15 in

Fig 4-2 Vacuum Chamber Main Body

The chamber is made up of 6 pass ways pass way A is the connection with the Laser Deposition

Equipment pass way B is the connection with the Turbo Pump and pass way C is for the connection with

the Deposition Source

A

C

B

79

Pass way C is for the deposition source as mentioned above This is a system where a thermal

resistance is heated by passing a high current through it which heats up a filament boat (made of tungsten)

where the material to be evaporated is place We control the temperature as such that the material will

evaporate and the heat will not cause the filament boat to crack

Because P = Isup2 R (where P is power I is current and R is resistance) to avoid the current to flow

where it is not desired we decided that the material for the Thermocouple shown in figure 4-3 should be

Copper ᴓ 63 mm We choose it that way because Copper has very good heat dissipation characteristics

and the resistance value is low It can reduce the value of the current enough to make the thermocouple to

create heat

Fig 4-3 Thermocouple

To the thermocouple we attach the tungsten filament boat We need to take notice of materials to be

used in this design because when using high current the tungsten filament boar will heat up and so the

material must be able to keep up with the heating potential of tungsten and has a low coefficient of heat

dissipation to avoid the tungsten to fail when heating up and therefore not evaporating Considering all

this we decide to use Stainless Steel

Because this clamp will be assembled inside the chamber after many revisions it was determined it

will have the shape shown in figure 4-4

Fig 4-4 Filament Boat Clamp Design

80

For the tungsten filament boat we bought the product from a distributor The dimensions are

Length 100 mm

Width 10 mm

Height 1 mm

Our thermocouple is 15 in but the pass way C is 4 in so we need to attach a Flange that connects

15in to 4in Because these specifications are quite difficult to achieve by Milling we had to use

electrical wire cutting

For the laser clamping system where the laser that is going to be AR coated will be placed will be

connected to pass way A the assembly is shown in figure 4-5 below

Fig 4-5 Cover Assembly

For this design we used an O-ring instead of a gasket so as to save time The design of the assembly

where the laser will be placed is shown in figure 4-6

Fig 4-6 Upper Cover Inner Assembly

D

E

F

81

Point D is the plate in the assembly where the laser diode will be fixed Because of the easy

processing we decide to use Aluminum and it is screwed to the top cover Point E is the connection for

the Quartz crystal resonator and it is designed in the same as point F in this way the results of the quartz

microbalance system will be more accurate in real time Point F is the final resting place for the laser

diode We use a Thor Labs Base with dimensions of ᴓ 9mm and ᴓ 56mm for two different size laser

diodes It just needs to be plugged in for easy installation

From figure 4-6 we know that the system needs signal system connections and because of the

change in temperature inside the chamber this could affect the functioning of the quartz microbalance so

we also need to install water tubes for cooling This is shown in figure 4-7 below

Fig 4-7 Diagram of Upper Cover Connections

In figure 4-8 we show the Feed through connections and their functions

Fig 4-8 Feed through Diagram

82

1 SQM-160 wire 5 Laser Connection 1 (Vin)

2 SQM-160 (G) 6 Laser Connection 2 (G)

3 K-Type-1 7 Laser Connection 3 (PD)

4 K-Type-2 8 Not In Use

The fully assembled chamber is shown in figure 4-9

Fig 4-9 Fully Assembled Chamber

422 Quartz Crystal Microbalance

For measuring the deposition on our target for coating we used the Inficon SQM-160 RateThickness

Monitor It is an easy to use instrument for measuring many types of thin-film coatings as shown in

figure 4-10

(a) Front Panel (b) Back Panel

Fig 4-10 Inficon SQM-160

83

Table 4-1 shows the technical specifications for this equipment

Number of sensors 2 Standard 4 additional optional

Sensor Frequency Range 40 MHz ~ 60 MHz

Reference Frequency Accuracy 002

Thickness Display Resolution 1 Aring

Thickness Resolution 015 Aring (Std) 0037 Aring (Hi Res)

Density of Stored Films 05-9999 gmcc

Tooling 10-399

Z-Factor 010-1000

Final Thickness 0000-9999k Aring

Measurement Period 15 to 2 sec

Simulation Mode Yes

Frequency Mode Yes

Rate Resolution 011 Arings

Dual Crystal Yes

Etch Mode Yes

Crystal Tooling 10-399

Crystal Fail Min Max 40 to 60 MHz 41 to 61 MHz

Power 100-120 200-240~plusmn10 nominal 20W

Operation Environment 0degC ~ 50degC

0 ~ 80 RH non-condensing

0 ~ 2000 meters

Class 1 Equipment

Pollution Degree 2

Rack Dimensions 885mm x 2127mm x 1969mm

Weight 27 kg

Table 4-1 Inficon SQM-160 RateThickness Monitor Specs

84

To the SQM-160 we need to connect an Oscillator We use the Sigma Instruments Remote Oscillator

Ser No 2 268 as shown in figure 4-11

Fig 4-11 Sigma Instruments Remote Oscillator

The connections diagram is shown in figure 4-12

Fig 4-12 SQM-160 Connections Diagram

85

423 Turbo Pump

For our experiments we used the Pfeiffer TCP 015 Electronic Drive Unit shown below in figure 4-13

Table 4-2 shows the technical specifications for this equipment

(a) Front Panel (b) Back Panel

Fig 4-13 Pfeiffer TCP 015 Electronic Drive

Connection Voltage (100V) 90-112

Mains Frequency 5060 Hz

Start-up Current 22 A

Nominal Frequency 1500 Hz

Rotation Speed 10V = 1500Hz plusmn2

Analog Output Current 10 V = 25 A plusmn 5

Rotation Speed Switchpoint 750 Hz

Works Setting 8 min

Permissible Ambient Temperature 0degC ~ 40degC

Dimensions Front Panel 1285mm x 1063mm

Insertion Length 227mm

Weight 27 Kg

Table 4-2 Pfeiffer TCP 015 Electronic Drive Specs

86

The connections diagram is shown in figure 4-14

Fig 4-14Connections Diagram for Pfeiffer TCP 015

To measure the pressure inside the chamber we use the Granville Phillips 375 Convectron Vacuum

Pressure Controller shown in figure 4-15

(a) Front Panel (b) Back Panel

Fig 4-15 Granville Phillips 375 Convectron

87

Its dimensions are shown in figure 4-16

Fig 4-16 Dimensions of Convectron

Table 4-3 shows the technical specifications for this equipment

Table 4-3 Granville Phillips 375 Convectron Vacuum Pressure Controller Specs

88

424 Multimeter

For our experiment we used the Keithley 2000 Digital Multimeter as shown in figure 4-17

(a) Front Panel (b) Back Panel

Fig 4-17 Keithley Model 2000 6-12-Digit Digital Multimeter

Its technical specifications are shown in table 4-4

Table 4-4 Keithley Model 2000 6-12-Digit Digital Multimeter Specs

89

43 Experiment Procedure

1 Connecting together the equipment and the chamber

(1) We first connect the resonator to the thickness monitor and connect the other side to the

chamber

(2) We now connect the flexible tubes to the turbo pump on one side and to the chamber on the

other

(3) We need to check that tubes are tightly connected to avoid any leaks in the vacuum pumping

process which will not allow us to get to our goal of Torr As shown in figure 4-18

(4) Connect the convectron to the system as shown in figure 4-19

Fig 4-18 checking for leaks using alcohol

Fig 4-19 Convectron attached to System

90

(5) Attach the clamps of the Multimeter to the bottom of the chamber as shown in figure 4-20

(6) Place the Quartz crystal in place

(7) Close tight vacuum chamber

(8) Connect all electrical appliances to power source

Fig 4-20 Multimeter Connections

2 Starting up the System

(1) We turn on all the devices as such Check all systems are ready to function Reset all values

that might be left over from previous tests

(2) Start the thickness monitor and set all values for this experiment In our case we got to testing

the system but not actual coating So we used the simulation mode of the thickness monitor as

shown in figure 4-21

Fig 4-21 Simulation Mode

91

(3) Start the turbo pump Make sure the lid on the vacuum chamber is tightly closed

(4) Start convectron and record initial pressure

(5) Start Multimeter and record initial current

3 Coating Process

(1) If we have the deposition material inside the filament boat the power source for the high

current must be started as well

(2) Record all initial values for thickness current pressure

(3) For an ideal experiment we need a thickness of around 101 nm a pressure of Torr and

a current of 300 A

44 Results

From previous experiments we have shown that we can turn a LED into a laser by means of AR

Coating In figure 4-22 shown below we can compare the actual results of a Diode before and after AR

coating From the blue line we can see that when the diode is at a current of 15mA its light will change

from LED to laser and if we look at the red line its critical current is around 30 to 35 mA

Fig 4-22 AR Coating Comparison for Laser Diodes

This means that the light emitted is not as strong as if the diode had been coated because inside the

chamber there must be some excitation first so the reflectivity of both sides inside the diode must be high

So because of the coating in one of the sides we have opened a door and let the light come out so the

critical current is risen as such and will be higher value than that of before the coating

92

In the following figures we can see the difference between before and after coating in a material The

thickness is around 1016 nm for this material

Fig 4-23 Before Coating

Fig 4-24 After Coating

93

Chapter 5 CONCLUSIONS AND RECOMMENDATIONS

51 Conclusions

For the first part of this independent study taking into consideration the data that came out of our

research and that sent by the provider we can say

1 SUM 23 after heat treatment will unexpectedly develop cracking in the middle of the tensile

testing process and suddenly break

2 Itrsquos possible that in the process of heat treatment to the SUM 23 material the treatment was not

uniform and this will create a pre-loaded moment force on one side that pushes on the other side

of the specimen resulting in material deformation

3 In the process of attaching the strain gauges to the materials it is very easy to make errors due to

poor adhesion or sudden removal in the tensile testing process

For our second part of the independent study the following can be made

1 At the beginning of this independent study we had no idea what Bose-Einstein Condensate was

or what was its purpose After much literature we finally comprehended the basic principles to

put into practice for our research

2 Our systemrsquos basic working principles and equipmentrsquos complexity are a little difficult to grasp

but hopefully we were able to understand enough of it

3 Theoretically from relation between the power and current we can know the advantages and

disadvantages of AR Coating

4 We were able to assemble the system and run test on its functions Even though we were able to

do this there is still much more work left to do with this system

52 Recommendations

For the Tensile Testing the following can be said

1 Ask the provider to check on the process of heat treatment on the SUM 23 material and give

them the information we have gathered through our test so they can correct for the mechanical

properties found if any change is needed

2 To avoid the problem of the inaccuracy of the poor adhesion of strain gauges we can attach

multiple strain gauges to the same one specimen so as to correlate data and improve our results

For the AR Coating the following can be said

1 We need to make sure that there are no physical defects on the main body of the chamber so as to

achieve maximum efficiency in the vacuum process If there was then the vacuum will arrive to

certain point and then start to decrease

2 It would be preferable to add some sort of visual aid that will allow the user to check the inside of

the chamber without actually opening it This will help us determine at what times we should

manipulate the current to better evaporate the substrate

94

REFERENCES

[1] A L Window Strain Gauge Technology Elsevier Applied Science London and New York 2nd

Edition 1992

[2] CC Perry and HR Lissner Strain Gauge Primer McGraw-Hill Book Co Inc New York 1955

[3] James W Dally William F Riley McGraw-Hill 1978

[4] University of Colorado Boulder BEC - What is it and where did the idea come from

httpwwwcoloradoeduphysics2000becwhat_is_ithtml

[5] Ultraslow Light amp Bose-Einstein Condensates Two-way Control with Coherent Light amp Atom

Fields Harvard Hau Lab Dr Lene Vestergaard Hau Optics amp Photonics News 16 1995

[6] The Art of Taming Light Ultra-slow and Stopped Light Harvard Hau Lab Dr Lene

Vestergaard Hau Europhysics News 2004

[7] Nonlinear Optics Shocking Superfluids Harvard Hau Lab Dr Lene Vestergaard Hau Nature

Physics 2007

[8] Model P3 Strain Indicator and Recorder Instruction Manual Vishay Micro-Measurements 2005

[9] Granville-Phillips Series 375 Convectron Vacuum Gauge Controller Instruction Manual Brooks

Automation 2008

[10] Effect of Film Thickness on the Validity of the Sauerbrey Equation for Hydrated Polyelectrolyte

Films Vogt Lin Wu White 2004

[11] Quartz Crystal Microbalance Study of DNA Immobilization and Hybridization for DNA Sensor

Development Chang Zhao 2008

[12] Installation of Strain Gages with SR-4 PrecoatAdhesive Vishay Micro-Measurements 2005

[13] Strain Gauge Measurement ndash A Tutorial National Instruments 1998

[14] Correlation between Vickers Hardness Number and Yield Stress of Cold-Formed Products

Yavuz Tekkaya

[15] httpsenwikipediaorg

Page 66: PC Hinge Materials Testing and AR Laser Diode Coating

66

(b)

(c)

Fig 3-19 Cut-Off Surface of (a) 1 Round Bar 2 Round Bar and (c) 3 Round Bar

67

342 SUM 43

Fig 3-20 Untreated SUM 43 Untreated Material

Number 1 5

Hardness(HRB) 76 75

Yield Stress (MPa) 572 594

Tensile Strength (MPa) 743 785

Poissonrsquos Ratio 027 029

Youngrsquos Modulus (GPa) 200 202

Cut-off Area Shrinking () 338 2944

Elongation () 857 894

Table 3-8 Mechanical Properties of SUM 43 Untreated

68

Stress-Strain Diagrams

(a)

(b)

Fig 3-21 Stress-Strain Diagrams for SUM 43 (a) 1 Round Bar and (b) 5 Round Bar

69

Cut-Off Area

(a)

(b)

Fig 3-22 Cut-Off Area of SUM 43 (a) 1 Round Bar and (b) 5 Round Bar

70

SUM 43 Nickel Round Bar

Fig 3-23 SUM 43 Nickel Material

Number 4 5

Hardness(HRB) 51 50

Yield Stress (MPa) 1580 1544

Tensile Strength (MPa) 1639 1625

Poissonrsquos Ratio 03 028

Youngrsquos Modulus (GPa) 194 201

Cut-off Area Shrinking () 1697 137

Elongation () 376 265

Table 3-9 Mechanical Properties of SUM 43 Nickel

71

Stress-Strain Diagrams

(a)

(b)

Fig 3-24 Stress-Strain Diagrams for (a) 4 Round Bar and (b) 5 Round Bar

72

Cut-Off Area

(a)

(b)

Fig 3-25 Cut-Off Area of (a) 4 Round Bar and (b) 5 Round Bar

73

SUM 43 Black Surface Material

Fig 3-26 SUM 43 Black Surface Material

Number 3 5

Hardness(HRB) 56 56

Yield Stress (MPa) 1416 1361

Tensile Strength (MPa) 1591 1402

Poissonrsquos Ratio 029 031

Youngrsquos Modulus (GPa) 200 202

Cut-off Area Shrinking () 139 124

Elongation () 24 24

Table 3-10 Mechanical Properties of SUM 43 Black Surface Material

74

Stress-Strain Diagrams

0 2 4 6 8 10 12 14

-200

0

200

400

600

800

1000

1200

1400

1600

1800

應力 (MPa)

應變()

(a)

0 2 4 6 8 10

-200

0

200

400

600

800

1000

1200

1400

1600

應力

(MPa)

位移 ()

(b)

Fig 3-27 Stress-Strain Diagrams for (a) 3 Round Bar and (b) 5 Round Bar

(Note These curves were formulated using Visual Solutions Inc VisSim Software)

75

Cut-Off Area

(a)

(b)

Fig 3-28 Cut-Off Area of (a) 3 Round Bar and (b) 5 Round Bar

76

The force value (N) was retrieved from the Universal Testing Machine

The Poissonrsquos Ratio (ε) is calculated as

ε =

the values for the Poissonrsquos Ratio are in average around 0297

The Youngrsquos Modulus (E) is calculated as

E =

Where

Stress =

Cross-sectional Area =

where D is the Diameter

The value for D was in average around 1258 mm

The values shown by the computer because there is Slippage phenomena between the Clamp and the

specimen will not be taken into consideration for the elongation strain and Youngrsquos modulus and we will

refer to the values that we have meticulously calculated

77

Chapter 4 AR COATING IN DEPTH

41 Experimentrsquos Purpose and Principles

By means of a vacuum chamber and several other instruments we intend to apply Anti-Reflective

Coating using deposition process to a laser diode and in this way reduce its refraction so as to make it

lose less light in the process of amplification and we can control certain wavelengths we want produced

for certain desired applications in our case we are attempting to re-create a Bose-Einstein Condensate

An optimal BEC apparatus is shown in figure 4-1

Fig 4-1 BEC Apparatus

The main point of this experiment is to build a vacuum chamber system attach all the instrumentation

needed (Vacuum pump deposition meter and voltmeter) and use it to apply AR coating to a laser diode

After we have accomplished the AR coating other team will be in charge of designing the BEC apparatus

and use the results of our research

78

42 Experimentrsquos Equipment

421 Vacuum Chamber

For this research we designed a vacuum chamber whose main body is shown in figure 4-2 Its

dimensions are

Width 240 mm

Length 240 mm

Height 200 mm

Outer Diameter 4 in

Inner Diameter 15 in

Fig 4-2 Vacuum Chamber Main Body

The chamber is made up of 6 pass ways pass way A is the connection with the Laser Deposition

Equipment pass way B is the connection with the Turbo Pump and pass way C is for the connection with

the Deposition Source

A

C

B

79

Pass way C is for the deposition source as mentioned above This is a system where a thermal

resistance is heated by passing a high current through it which heats up a filament boat (made of tungsten)

where the material to be evaporated is place We control the temperature as such that the material will

evaporate and the heat will not cause the filament boat to crack

Because P = Isup2 R (where P is power I is current and R is resistance) to avoid the current to flow

where it is not desired we decided that the material for the Thermocouple shown in figure 4-3 should be

Copper ᴓ 63 mm We choose it that way because Copper has very good heat dissipation characteristics

and the resistance value is low It can reduce the value of the current enough to make the thermocouple to

create heat

Fig 4-3 Thermocouple

To the thermocouple we attach the tungsten filament boat We need to take notice of materials to be

used in this design because when using high current the tungsten filament boar will heat up and so the

material must be able to keep up with the heating potential of tungsten and has a low coefficient of heat

dissipation to avoid the tungsten to fail when heating up and therefore not evaporating Considering all

this we decide to use Stainless Steel

Because this clamp will be assembled inside the chamber after many revisions it was determined it

will have the shape shown in figure 4-4

Fig 4-4 Filament Boat Clamp Design

80

For the tungsten filament boat we bought the product from a distributor The dimensions are

Length 100 mm

Width 10 mm

Height 1 mm

Our thermocouple is 15 in but the pass way C is 4 in so we need to attach a Flange that connects

15in to 4in Because these specifications are quite difficult to achieve by Milling we had to use

electrical wire cutting

For the laser clamping system where the laser that is going to be AR coated will be placed will be

connected to pass way A the assembly is shown in figure 4-5 below

Fig 4-5 Cover Assembly

For this design we used an O-ring instead of a gasket so as to save time The design of the assembly

where the laser will be placed is shown in figure 4-6

Fig 4-6 Upper Cover Inner Assembly

D

E

F

81

Point D is the plate in the assembly where the laser diode will be fixed Because of the easy

processing we decide to use Aluminum and it is screwed to the top cover Point E is the connection for

the Quartz crystal resonator and it is designed in the same as point F in this way the results of the quartz

microbalance system will be more accurate in real time Point F is the final resting place for the laser

diode We use a Thor Labs Base with dimensions of ᴓ 9mm and ᴓ 56mm for two different size laser

diodes It just needs to be plugged in for easy installation

From figure 4-6 we know that the system needs signal system connections and because of the

change in temperature inside the chamber this could affect the functioning of the quartz microbalance so

we also need to install water tubes for cooling This is shown in figure 4-7 below

Fig 4-7 Diagram of Upper Cover Connections

In figure 4-8 we show the Feed through connections and their functions

Fig 4-8 Feed through Diagram

82

1 SQM-160 wire 5 Laser Connection 1 (Vin)

2 SQM-160 (G) 6 Laser Connection 2 (G)

3 K-Type-1 7 Laser Connection 3 (PD)

4 K-Type-2 8 Not In Use

The fully assembled chamber is shown in figure 4-9

Fig 4-9 Fully Assembled Chamber

422 Quartz Crystal Microbalance

For measuring the deposition on our target for coating we used the Inficon SQM-160 RateThickness

Monitor It is an easy to use instrument for measuring many types of thin-film coatings as shown in

figure 4-10

(a) Front Panel (b) Back Panel

Fig 4-10 Inficon SQM-160

83

Table 4-1 shows the technical specifications for this equipment

Number of sensors 2 Standard 4 additional optional

Sensor Frequency Range 40 MHz ~ 60 MHz

Reference Frequency Accuracy 002

Thickness Display Resolution 1 Aring

Thickness Resolution 015 Aring (Std) 0037 Aring (Hi Res)

Density of Stored Films 05-9999 gmcc

Tooling 10-399

Z-Factor 010-1000

Final Thickness 0000-9999k Aring

Measurement Period 15 to 2 sec

Simulation Mode Yes

Frequency Mode Yes

Rate Resolution 011 Arings

Dual Crystal Yes

Etch Mode Yes

Crystal Tooling 10-399

Crystal Fail Min Max 40 to 60 MHz 41 to 61 MHz

Power 100-120 200-240~plusmn10 nominal 20W

Operation Environment 0degC ~ 50degC

0 ~ 80 RH non-condensing

0 ~ 2000 meters

Class 1 Equipment

Pollution Degree 2

Rack Dimensions 885mm x 2127mm x 1969mm

Weight 27 kg

Table 4-1 Inficon SQM-160 RateThickness Monitor Specs

84

To the SQM-160 we need to connect an Oscillator We use the Sigma Instruments Remote Oscillator

Ser No 2 268 as shown in figure 4-11

Fig 4-11 Sigma Instruments Remote Oscillator

The connections diagram is shown in figure 4-12

Fig 4-12 SQM-160 Connections Diagram

85

423 Turbo Pump

For our experiments we used the Pfeiffer TCP 015 Electronic Drive Unit shown below in figure 4-13

Table 4-2 shows the technical specifications for this equipment

(a) Front Panel (b) Back Panel

Fig 4-13 Pfeiffer TCP 015 Electronic Drive

Connection Voltage (100V) 90-112

Mains Frequency 5060 Hz

Start-up Current 22 A

Nominal Frequency 1500 Hz

Rotation Speed 10V = 1500Hz plusmn2

Analog Output Current 10 V = 25 A plusmn 5

Rotation Speed Switchpoint 750 Hz

Works Setting 8 min

Permissible Ambient Temperature 0degC ~ 40degC

Dimensions Front Panel 1285mm x 1063mm

Insertion Length 227mm

Weight 27 Kg

Table 4-2 Pfeiffer TCP 015 Electronic Drive Specs

86

The connections diagram is shown in figure 4-14

Fig 4-14Connections Diagram for Pfeiffer TCP 015

To measure the pressure inside the chamber we use the Granville Phillips 375 Convectron Vacuum

Pressure Controller shown in figure 4-15

(a) Front Panel (b) Back Panel

Fig 4-15 Granville Phillips 375 Convectron

87

Its dimensions are shown in figure 4-16

Fig 4-16 Dimensions of Convectron

Table 4-3 shows the technical specifications for this equipment

Table 4-3 Granville Phillips 375 Convectron Vacuum Pressure Controller Specs

88

424 Multimeter

For our experiment we used the Keithley 2000 Digital Multimeter as shown in figure 4-17

(a) Front Panel (b) Back Panel

Fig 4-17 Keithley Model 2000 6-12-Digit Digital Multimeter

Its technical specifications are shown in table 4-4

Table 4-4 Keithley Model 2000 6-12-Digit Digital Multimeter Specs

89

43 Experiment Procedure

1 Connecting together the equipment and the chamber

(1) We first connect the resonator to the thickness monitor and connect the other side to the

chamber

(2) We now connect the flexible tubes to the turbo pump on one side and to the chamber on the

other

(3) We need to check that tubes are tightly connected to avoid any leaks in the vacuum pumping

process which will not allow us to get to our goal of Torr As shown in figure 4-18

(4) Connect the convectron to the system as shown in figure 4-19

Fig 4-18 checking for leaks using alcohol

Fig 4-19 Convectron attached to System

90

(5) Attach the clamps of the Multimeter to the bottom of the chamber as shown in figure 4-20

(6) Place the Quartz crystal in place

(7) Close tight vacuum chamber

(8) Connect all electrical appliances to power source

Fig 4-20 Multimeter Connections

2 Starting up the System

(1) We turn on all the devices as such Check all systems are ready to function Reset all values

that might be left over from previous tests

(2) Start the thickness monitor and set all values for this experiment In our case we got to testing

the system but not actual coating So we used the simulation mode of the thickness monitor as

shown in figure 4-21

Fig 4-21 Simulation Mode

91

(3) Start the turbo pump Make sure the lid on the vacuum chamber is tightly closed

(4) Start convectron and record initial pressure

(5) Start Multimeter and record initial current

3 Coating Process

(1) If we have the deposition material inside the filament boat the power source for the high

current must be started as well

(2) Record all initial values for thickness current pressure

(3) For an ideal experiment we need a thickness of around 101 nm a pressure of Torr and

a current of 300 A

44 Results

From previous experiments we have shown that we can turn a LED into a laser by means of AR

Coating In figure 4-22 shown below we can compare the actual results of a Diode before and after AR

coating From the blue line we can see that when the diode is at a current of 15mA its light will change

from LED to laser and if we look at the red line its critical current is around 30 to 35 mA

Fig 4-22 AR Coating Comparison for Laser Diodes

This means that the light emitted is not as strong as if the diode had been coated because inside the

chamber there must be some excitation first so the reflectivity of both sides inside the diode must be high

So because of the coating in one of the sides we have opened a door and let the light come out so the

critical current is risen as such and will be higher value than that of before the coating

92

In the following figures we can see the difference between before and after coating in a material The

thickness is around 1016 nm for this material

Fig 4-23 Before Coating

Fig 4-24 After Coating

93

Chapter 5 CONCLUSIONS AND RECOMMENDATIONS

51 Conclusions

For the first part of this independent study taking into consideration the data that came out of our

research and that sent by the provider we can say

1 SUM 23 after heat treatment will unexpectedly develop cracking in the middle of the tensile

testing process and suddenly break

2 Itrsquos possible that in the process of heat treatment to the SUM 23 material the treatment was not

uniform and this will create a pre-loaded moment force on one side that pushes on the other side

of the specimen resulting in material deformation

3 In the process of attaching the strain gauges to the materials it is very easy to make errors due to

poor adhesion or sudden removal in the tensile testing process

For our second part of the independent study the following can be made

1 At the beginning of this independent study we had no idea what Bose-Einstein Condensate was

or what was its purpose After much literature we finally comprehended the basic principles to

put into practice for our research

2 Our systemrsquos basic working principles and equipmentrsquos complexity are a little difficult to grasp

but hopefully we were able to understand enough of it

3 Theoretically from relation between the power and current we can know the advantages and

disadvantages of AR Coating

4 We were able to assemble the system and run test on its functions Even though we were able to

do this there is still much more work left to do with this system

52 Recommendations

For the Tensile Testing the following can be said

1 Ask the provider to check on the process of heat treatment on the SUM 23 material and give

them the information we have gathered through our test so they can correct for the mechanical

properties found if any change is needed

2 To avoid the problem of the inaccuracy of the poor adhesion of strain gauges we can attach

multiple strain gauges to the same one specimen so as to correlate data and improve our results

For the AR Coating the following can be said

1 We need to make sure that there are no physical defects on the main body of the chamber so as to

achieve maximum efficiency in the vacuum process If there was then the vacuum will arrive to

certain point and then start to decrease

2 It would be preferable to add some sort of visual aid that will allow the user to check the inside of

the chamber without actually opening it This will help us determine at what times we should

manipulate the current to better evaporate the substrate

94

REFERENCES

[1] A L Window Strain Gauge Technology Elsevier Applied Science London and New York 2nd

Edition 1992

[2] CC Perry and HR Lissner Strain Gauge Primer McGraw-Hill Book Co Inc New York 1955

[3] James W Dally William F Riley McGraw-Hill 1978

[4] University of Colorado Boulder BEC - What is it and where did the idea come from

httpwwwcoloradoeduphysics2000becwhat_is_ithtml

[5] Ultraslow Light amp Bose-Einstein Condensates Two-way Control with Coherent Light amp Atom

Fields Harvard Hau Lab Dr Lene Vestergaard Hau Optics amp Photonics News 16 1995

[6] The Art of Taming Light Ultra-slow and Stopped Light Harvard Hau Lab Dr Lene

Vestergaard Hau Europhysics News 2004

[7] Nonlinear Optics Shocking Superfluids Harvard Hau Lab Dr Lene Vestergaard Hau Nature

Physics 2007

[8] Model P3 Strain Indicator and Recorder Instruction Manual Vishay Micro-Measurements 2005

[9] Granville-Phillips Series 375 Convectron Vacuum Gauge Controller Instruction Manual Brooks

Automation 2008

[10] Effect of Film Thickness on the Validity of the Sauerbrey Equation for Hydrated Polyelectrolyte

Films Vogt Lin Wu White 2004

[11] Quartz Crystal Microbalance Study of DNA Immobilization and Hybridization for DNA Sensor

Development Chang Zhao 2008

[12] Installation of Strain Gages with SR-4 PrecoatAdhesive Vishay Micro-Measurements 2005

[13] Strain Gauge Measurement ndash A Tutorial National Instruments 1998

[14] Correlation between Vickers Hardness Number and Yield Stress of Cold-Formed Products

Yavuz Tekkaya

[15] httpsenwikipediaorg

Page 67: PC Hinge Materials Testing and AR Laser Diode Coating

67

342 SUM 43

Fig 3-20 Untreated SUM 43 Untreated Material

Number 1 5

Hardness(HRB) 76 75

Yield Stress (MPa) 572 594

Tensile Strength (MPa) 743 785

Poissonrsquos Ratio 027 029

Youngrsquos Modulus (GPa) 200 202

Cut-off Area Shrinking () 338 2944

Elongation () 857 894

Table 3-8 Mechanical Properties of SUM 43 Untreated

68

Stress-Strain Diagrams

(a)

(b)

Fig 3-21 Stress-Strain Diagrams for SUM 43 (a) 1 Round Bar and (b) 5 Round Bar

69

Cut-Off Area

(a)

(b)

Fig 3-22 Cut-Off Area of SUM 43 (a) 1 Round Bar and (b) 5 Round Bar

70

SUM 43 Nickel Round Bar

Fig 3-23 SUM 43 Nickel Material

Number 4 5

Hardness(HRB) 51 50

Yield Stress (MPa) 1580 1544

Tensile Strength (MPa) 1639 1625

Poissonrsquos Ratio 03 028

Youngrsquos Modulus (GPa) 194 201

Cut-off Area Shrinking () 1697 137

Elongation () 376 265

Table 3-9 Mechanical Properties of SUM 43 Nickel

71

Stress-Strain Diagrams

(a)

(b)

Fig 3-24 Stress-Strain Diagrams for (a) 4 Round Bar and (b) 5 Round Bar

72

Cut-Off Area

(a)

(b)

Fig 3-25 Cut-Off Area of (a) 4 Round Bar and (b) 5 Round Bar

73

SUM 43 Black Surface Material

Fig 3-26 SUM 43 Black Surface Material

Number 3 5

Hardness(HRB) 56 56

Yield Stress (MPa) 1416 1361

Tensile Strength (MPa) 1591 1402

Poissonrsquos Ratio 029 031

Youngrsquos Modulus (GPa) 200 202

Cut-off Area Shrinking () 139 124

Elongation () 24 24

Table 3-10 Mechanical Properties of SUM 43 Black Surface Material

74

Stress-Strain Diagrams

0 2 4 6 8 10 12 14

-200

0

200

400

600

800

1000

1200

1400

1600

1800

應力 (MPa)

應變()

(a)

0 2 4 6 8 10

-200

0

200

400

600

800

1000

1200

1400

1600

應力

(MPa)

位移 ()

(b)

Fig 3-27 Stress-Strain Diagrams for (a) 3 Round Bar and (b) 5 Round Bar

(Note These curves were formulated using Visual Solutions Inc VisSim Software)

75

Cut-Off Area

(a)

(b)

Fig 3-28 Cut-Off Area of (a) 3 Round Bar and (b) 5 Round Bar

76

The force value (N) was retrieved from the Universal Testing Machine

The Poissonrsquos Ratio (ε) is calculated as

ε =

the values for the Poissonrsquos Ratio are in average around 0297

The Youngrsquos Modulus (E) is calculated as

E =

Where

Stress =

Cross-sectional Area =

where D is the Diameter

The value for D was in average around 1258 mm

The values shown by the computer because there is Slippage phenomena between the Clamp and the

specimen will not be taken into consideration for the elongation strain and Youngrsquos modulus and we will

refer to the values that we have meticulously calculated

77

Chapter 4 AR COATING IN DEPTH

41 Experimentrsquos Purpose and Principles

By means of a vacuum chamber and several other instruments we intend to apply Anti-Reflective

Coating using deposition process to a laser diode and in this way reduce its refraction so as to make it

lose less light in the process of amplification and we can control certain wavelengths we want produced

for certain desired applications in our case we are attempting to re-create a Bose-Einstein Condensate

An optimal BEC apparatus is shown in figure 4-1

Fig 4-1 BEC Apparatus

The main point of this experiment is to build a vacuum chamber system attach all the instrumentation

needed (Vacuum pump deposition meter and voltmeter) and use it to apply AR coating to a laser diode

After we have accomplished the AR coating other team will be in charge of designing the BEC apparatus

and use the results of our research

78

42 Experimentrsquos Equipment

421 Vacuum Chamber

For this research we designed a vacuum chamber whose main body is shown in figure 4-2 Its

dimensions are

Width 240 mm

Length 240 mm

Height 200 mm

Outer Diameter 4 in

Inner Diameter 15 in

Fig 4-2 Vacuum Chamber Main Body

The chamber is made up of 6 pass ways pass way A is the connection with the Laser Deposition

Equipment pass way B is the connection with the Turbo Pump and pass way C is for the connection with

the Deposition Source

A

C

B

79

Pass way C is for the deposition source as mentioned above This is a system where a thermal

resistance is heated by passing a high current through it which heats up a filament boat (made of tungsten)

where the material to be evaporated is place We control the temperature as such that the material will

evaporate and the heat will not cause the filament boat to crack

Because P = Isup2 R (where P is power I is current and R is resistance) to avoid the current to flow

where it is not desired we decided that the material for the Thermocouple shown in figure 4-3 should be

Copper ᴓ 63 mm We choose it that way because Copper has very good heat dissipation characteristics

and the resistance value is low It can reduce the value of the current enough to make the thermocouple to

create heat

Fig 4-3 Thermocouple

To the thermocouple we attach the tungsten filament boat We need to take notice of materials to be

used in this design because when using high current the tungsten filament boar will heat up and so the

material must be able to keep up with the heating potential of tungsten and has a low coefficient of heat

dissipation to avoid the tungsten to fail when heating up and therefore not evaporating Considering all

this we decide to use Stainless Steel

Because this clamp will be assembled inside the chamber after many revisions it was determined it

will have the shape shown in figure 4-4

Fig 4-4 Filament Boat Clamp Design

80

For the tungsten filament boat we bought the product from a distributor The dimensions are

Length 100 mm

Width 10 mm

Height 1 mm

Our thermocouple is 15 in but the pass way C is 4 in so we need to attach a Flange that connects

15in to 4in Because these specifications are quite difficult to achieve by Milling we had to use

electrical wire cutting

For the laser clamping system where the laser that is going to be AR coated will be placed will be

connected to pass way A the assembly is shown in figure 4-5 below

Fig 4-5 Cover Assembly

For this design we used an O-ring instead of a gasket so as to save time The design of the assembly

where the laser will be placed is shown in figure 4-6

Fig 4-6 Upper Cover Inner Assembly

D

E

F

81

Point D is the plate in the assembly where the laser diode will be fixed Because of the easy

processing we decide to use Aluminum and it is screwed to the top cover Point E is the connection for

the Quartz crystal resonator and it is designed in the same as point F in this way the results of the quartz

microbalance system will be more accurate in real time Point F is the final resting place for the laser

diode We use a Thor Labs Base with dimensions of ᴓ 9mm and ᴓ 56mm for two different size laser

diodes It just needs to be plugged in for easy installation

From figure 4-6 we know that the system needs signal system connections and because of the

change in temperature inside the chamber this could affect the functioning of the quartz microbalance so

we also need to install water tubes for cooling This is shown in figure 4-7 below

Fig 4-7 Diagram of Upper Cover Connections

In figure 4-8 we show the Feed through connections and their functions

Fig 4-8 Feed through Diagram

82

1 SQM-160 wire 5 Laser Connection 1 (Vin)

2 SQM-160 (G) 6 Laser Connection 2 (G)

3 K-Type-1 7 Laser Connection 3 (PD)

4 K-Type-2 8 Not In Use

The fully assembled chamber is shown in figure 4-9

Fig 4-9 Fully Assembled Chamber

422 Quartz Crystal Microbalance

For measuring the deposition on our target for coating we used the Inficon SQM-160 RateThickness

Monitor It is an easy to use instrument for measuring many types of thin-film coatings as shown in

figure 4-10

(a) Front Panel (b) Back Panel

Fig 4-10 Inficon SQM-160

83

Table 4-1 shows the technical specifications for this equipment

Number of sensors 2 Standard 4 additional optional

Sensor Frequency Range 40 MHz ~ 60 MHz

Reference Frequency Accuracy 002

Thickness Display Resolution 1 Aring

Thickness Resolution 015 Aring (Std) 0037 Aring (Hi Res)

Density of Stored Films 05-9999 gmcc

Tooling 10-399

Z-Factor 010-1000

Final Thickness 0000-9999k Aring

Measurement Period 15 to 2 sec

Simulation Mode Yes

Frequency Mode Yes

Rate Resolution 011 Arings

Dual Crystal Yes

Etch Mode Yes

Crystal Tooling 10-399

Crystal Fail Min Max 40 to 60 MHz 41 to 61 MHz

Power 100-120 200-240~plusmn10 nominal 20W

Operation Environment 0degC ~ 50degC

0 ~ 80 RH non-condensing

0 ~ 2000 meters

Class 1 Equipment

Pollution Degree 2

Rack Dimensions 885mm x 2127mm x 1969mm

Weight 27 kg

Table 4-1 Inficon SQM-160 RateThickness Monitor Specs

84

To the SQM-160 we need to connect an Oscillator We use the Sigma Instruments Remote Oscillator

Ser No 2 268 as shown in figure 4-11

Fig 4-11 Sigma Instruments Remote Oscillator

The connections diagram is shown in figure 4-12

Fig 4-12 SQM-160 Connections Diagram

85

423 Turbo Pump

For our experiments we used the Pfeiffer TCP 015 Electronic Drive Unit shown below in figure 4-13

Table 4-2 shows the technical specifications for this equipment

(a) Front Panel (b) Back Panel

Fig 4-13 Pfeiffer TCP 015 Electronic Drive

Connection Voltage (100V) 90-112

Mains Frequency 5060 Hz

Start-up Current 22 A

Nominal Frequency 1500 Hz

Rotation Speed 10V = 1500Hz plusmn2

Analog Output Current 10 V = 25 A plusmn 5

Rotation Speed Switchpoint 750 Hz

Works Setting 8 min

Permissible Ambient Temperature 0degC ~ 40degC

Dimensions Front Panel 1285mm x 1063mm

Insertion Length 227mm

Weight 27 Kg

Table 4-2 Pfeiffer TCP 015 Electronic Drive Specs

86

The connections diagram is shown in figure 4-14

Fig 4-14Connections Diagram for Pfeiffer TCP 015

To measure the pressure inside the chamber we use the Granville Phillips 375 Convectron Vacuum

Pressure Controller shown in figure 4-15

(a) Front Panel (b) Back Panel

Fig 4-15 Granville Phillips 375 Convectron

87

Its dimensions are shown in figure 4-16

Fig 4-16 Dimensions of Convectron

Table 4-3 shows the technical specifications for this equipment

Table 4-3 Granville Phillips 375 Convectron Vacuum Pressure Controller Specs

88

424 Multimeter

For our experiment we used the Keithley 2000 Digital Multimeter as shown in figure 4-17

(a) Front Panel (b) Back Panel

Fig 4-17 Keithley Model 2000 6-12-Digit Digital Multimeter

Its technical specifications are shown in table 4-4

Table 4-4 Keithley Model 2000 6-12-Digit Digital Multimeter Specs

89

43 Experiment Procedure

1 Connecting together the equipment and the chamber

(1) We first connect the resonator to the thickness monitor and connect the other side to the

chamber

(2) We now connect the flexible tubes to the turbo pump on one side and to the chamber on the

other

(3) We need to check that tubes are tightly connected to avoid any leaks in the vacuum pumping

process which will not allow us to get to our goal of Torr As shown in figure 4-18

(4) Connect the convectron to the system as shown in figure 4-19

Fig 4-18 checking for leaks using alcohol

Fig 4-19 Convectron attached to System

90

(5) Attach the clamps of the Multimeter to the bottom of the chamber as shown in figure 4-20

(6) Place the Quartz crystal in place

(7) Close tight vacuum chamber

(8) Connect all electrical appliances to power source

Fig 4-20 Multimeter Connections

2 Starting up the System

(1) We turn on all the devices as such Check all systems are ready to function Reset all values

that might be left over from previous tests

(2) Start the thickness monitor and set all values for this experiment In our case we got to testing

the system but not actual coating So we used the simulation mode of the thickness monitor as

shown in figure 4-21

Fig 4-21 Simulation Mode

91

(3) Start the turbo pump Make sure the lid on the vacuum chamber is tightly closed

(4) Start convectron and record initial pressure

(5) Start Multimeter and record initial current

3 Coating Process

(1) If we have the deposition material inside the filament boat the power source for the high

current must be started as well

(2) Record all initial values for thickness current pressure

(3) For an ideal experiment we need a thickness of around 101 nm a pressure of Torr and

a current of 300 A

44 Results

From previous experiments we have shown that we can turn a LED into a laser by means of AR

Coating In figure 4-22 shown below we can compare the actual results of a Diode before and after AR

coating From the blue line we can see that when the diode is at a current of 15mA its light will change

from LED to laser and if we look at the red line its critical current is around 30 to 35 mA

Fig 4-22 AR Coating Comparison for Laser Diodes

This means that the light emitted is not as strong as if the diode had been coated because inside the

chamber there must be some excitation first so the reflectivity of both sides inside the diode must be high

So because of the coating in one of the sides we have opened a door and let the light come out so the

critical current is risen as such and will be higher value than that of before the coating

92

In the following figures we can see the difference between before and after coating in a material The

thickness is around 1016 nm for this material

Fig 4-23 Before Coating

Fig 4-24 After Coating

93

Chapter 5 CONCLUSIONS AND RECOMMENDATIONS

51 Conclusions

For the first part of this independent study taking into consideration the data that came out of our

research and that sent by the provider we can say

1 SUM 23 after heat treatment will unexpectedly develop cracking in the middle of the tensile

testing process and suddenly break

2 Itrsquos possible that in the process of heat treatment to the SUM 23 material the treatment was not

uniform and this will create a pre-loaded moment force on one side that pushes on the other side

of the specimen resulting in material deformation

3 In the process of attaching the strain gauges to the materials it is very easy to make errors due to

poor adhesion or sudden removal in the tensile testing process

For our second part of the independent study the following can be made

1 At the beginning of this independent study we had no idea what Bose-Einstein Condensate was

or what was its purpose After much literature we finally comprehended the basic principles to

put into practice for our research

2 Our systemrsquos basic working principles and equipmentrsquos complexity are a little difficult to grasp

but hopefully we were able to understand enough of it

3 Theoretically from relation between the power and current we can know the advantages and

disadvantages of AR Coating

4 We were able to assemble the system and run test on its functions Even though we were able to

do this there is still much more work left to do with this system

52 Recommendations

For the Tensile Testing the following can be said

1 Ask the provider to check on the process of heat treatment on the SUM 23 material and give

them the information we have gathered through our test so they can correct for the mechanical

properties found if any change is needed

2 To avoid the problem of the inaccuracy of the poor adhesion of strain gauges we can attach

multiple strain gauges to the same one specimen so as to correlate data and improve our results

For the AR Coating the following can be said

1 We need to make sure that there are no physical defects on the main body of the chamber so as to

achieve maximum efficiency in the vacuum process If there was then the vacuum will arrive to

certain point and then start to decrease

2 It would be preferable to add some sort of visual aid that will allow the user to check the inside of

the chamber without actually opening it This will help us determine at what times we should

manipulate the current to better evaporate the substrate

94

REFERENCES

[1] A L Window Strain Gauge Technology Elsevier Applied Science London and New York 2nd

Edition 1992

[2] CC Perry and HR Lissner Strain Gauge Primer McGraw-Hill Book Co Inc New York 1955

[3] James W Dally William F Riley McGraw-Hill 1978

[4] University of Colorado Boulder BEC - What is it and where did the idea come from

httpwwwcoloradoeduphysics2000becwhat_is_ithtml

[5] Ultraslow Light amp Bose-Einstein Condensates Two-way Control with Coherent Light amp Atom

Fields Harvard Hau Lab Dr Lene Vestergaard Hau Optics amp Photonics News 16 1995

[6] The Art of Taming Light Ultra-slow and Stopped Light Harvard Hau Lab Dr Lene

Vestergaard Hau Europhysics News 2004

[7] Nonlinear Optics Shocking Superfluids Harvard Hau Lab Dr Lene Vestergaard Hau Nature

Physics 2007

[8] Model P3 Strain Indicator and Recorder Instruction Manual Vishay Micro-Measurements 2005

[9] Granville-Phillips Series 375 Convectron Vacuum Gauge Controller Instruction Manual Brooks

Automation 2008

[10] Effect of Film Thickness on the Validity of the Sauerbrey Equation for Hydrated Polyelectrolyte

Films Vogt Lin Wu White 2004

[11] Quartz Crystal Microbalance Study of DNA Immobilization and Hybridization for DNA Sensor

Development Chang Zhao 2008

[12] Installation of Strain Gages with SR-4 PrecoatAdhesive Vishay Micro-Measurements 2005

[13] Strain Gauge Measurement ndash A Tutorial National Instruments 1998

[14] Correlation between Vickers Hardness Number and Yield Stress of Cold-Formed Products

Yavuz Tekkaya

[15] httpsenwikipediaorg

Page 68: PC Hinge Materials Testing and AR Laser Diode Coating

68

Stress-Strain Diagrams

(a)

(b)

Fig 3-21 Stress-Strain Diagrams for SUM 43 (a) 1 Round Bar and (b) 5 Round Bar

69

Cut-Off Area

(a)

(b)

Fig 3-22 Cut-Off Area of SUM 43 (a) 1 Round Bar and (b) 5 Round Bar

70

SUM 43 Nickel Round Bar

Fig 3-23 SUM 43 Nickel Material

Number 4 5

Hardness(HRB) 51 50

Yield Stress (MPa) 1580 1544

Tensile Strength (MPa) 1639 1625

Poissonrsquos Ratio 03 028

Youngrsquos Modulus (GPa) 194 201

Cut-off Area Shrinking () 1697 137

Elongation () 376 265

Table 3-9 Mechanical Properties of SUM 43 Nickel

71

Stress-Strain Diagrams

(a)

(b)

Fig 3-24 Stress-Strain Diagrams for (a) 4 Round Bar and (b) 5 Round Bar

72

Cut-Off Area

(a)

(b)

Fig 3-25 Cut-Off Area of (a) 4 Round Bar and (b) 5 Round Bar

73

SUM 43 Black Surface Material

Fig 3-26 SUM 43 Black Surface Material

Number 3 5

Hardness(HRB) 56 56

Yield Stress (MPa) 1416 1361

Tensile Strength (MPa) 1591 1402

Poissonrsquos Ratio 029 031

Youngrsquos Modulus (GPa) 200 202

Cut-off Area Shrinking () 139 124

Elongation () 24 24

Table 3-10 Mechanical Properties of SUM 43 Black Surface Material

74

Stress-Strain Diagrams

0 2 4 6 8 10 12 14

-200

0

200

400

600

800

1000

1200

1400

1600

1800

應力 (MPa)

應變()

(a)

0 2 4 6 8 10

-200

0

200

400

600

800

1000

1200

1400

1600

應力

(MPa)

位移 ()

(b)

Fig 3-27 Stress-Strain Diagrams for (a) 3 Round Bar and (b) 5 Round Bar

(Note These curves were formulated using Visual Solutions Inc VisSim Software)

75

Cut-Off Area

(a)

(b)

Fig 3-28 Cut-Off Area of (a) 3 Round Bar and (b) 5 Round Bar

76

The force value (N) was retrieved from the Universal Testing Machine

The Poissonrsquos Ratio (ε) is calculated as

ε =

the values for the Poissonrsquos Ratio are in average around 0297

The Youngrsquos Modulus (E) is calculated as

E =

Where

Stress =

Cross-sectional Area =

where D is the Diameter

The value for D was in average around 1258 mm

The values shown by the computer because there is Slippage phenomena between the Clamp and the

specimen will not be taken into consideration for the elongation strain and Youngrsquos modulus and we will

refer to the values that we have meticulously calculated

77

Chapter 4 AR COATING IN DEPTH

41 Experimentrsquos Purpose and Principles

By means of a vacuum chamber and several other instruments we intend to apply Anti-Reflective

Coating using deposition process to a laser diode and in this way reduce its refraction so as to make it

lose less light in the process of amplification and we can control certain wavelengths we want produced

for certain desired applications in our case we are attempting to re-create a Bose-Einstein Condensate

An optimal BEC apparatus is shown in figure 4-1

Fig 4-1 BEC Apparatus

The main point of this experiment is to build a vacuum chamber system attach all the instrumentation

needed (Vacuum pump deposition meter and voltmeter) and use it to apply AR coating to a laser diode

After we have accomplished the AR coating other team will be in charge of designing the BEC apparatus

and use the results of our research

78

42 Experimentrsquos Equipment

421 Vacuum Chamber

For this research we designed a vacuum chamber whose main body is shown in figure 4-2 Its

dimensions are

Width 240 mm

Length 240 mm

Height 200 mm

Outer Diameter 4 in

Inner Diameter 15 in

Fig 4-2 Vacuum Chamber Main Body

The chamber is made up of 6 pass ways pass way A is the connection with the Laser Deposition

Equipment pass way B is the connection with the Turbo Pump and pass way C is for the connection with

the Deposition Source

A

C

B

79

Pass way C is for the deposition source as mentioned above This is a system where a thermal

resistance is heated by passing a high current through it which heats up a filament boat (made of tungsten)

where the material to be evaporated is place We control the temperature as such that the material will

evaporate and the heat will not cause the filament boat to crack

Because P = Isup2 R (where P is power I is current and R is resistance) to avoid the current to flow

where it is not desired we decided that the material for the Thermocouple shown in figure 4-3 should be

Copper ᴓ 63 mm We choose it that way because Copper has very good heat dissipation characteristics

and the resistance value is low It can reduce the value of the current enough to make the thermocouple to

create heat

Fig 4-3 Thermocouple

To the thermocouple we attach the tungsten filament boat We need to take notice of materials to be

used in this design because when using high current the tungsten filament boar will heat up and so the

material must be able to keep up with the heating potential of tungsten and has a low coefficient of heat

dissipation to avoid the tungsten to fail when heating up and therefore not evaporating Considering all

this we decide to use Stainless Steel

Because this clamp will be assembled inside the chamber after many revisions it was determined it

will have the shape shown in figure 4-4

Fig 4-4 Filament Boat Clamp Design

80

For the tungsten filament boat we bought the product from a distributor The dimensions are

Length 100 mm

Width 10 mm

Height 1 mm

Our thermocouple is 15 in but the pass way C is 4 in so we need to attach a Flange that connects

15in to 4in Because these specifications are quite difficult to achieve by Milling we had to use

electrical wire cutting

For the laser clamping system where the laser that is going to be AR coated will be placed will be

connected to pass way A the assembly is shown in figure 4-5 below

Fig 4-5 Cover Assembly

For this design we used an O-ring instead of a gasket so as to save time The design of the assembly

where the laser will be placed is shown in figure 4-6

Fig 4-6 Upper Cover Inner Assembly

D

E

F

81

Point D is the plate in the assembly where the laser diode will be fixed Because of the easy

processing we decide to use Aluminum and it is screwed to the top cover Point E is the connection for

the Quartz crystal resonator and it is designed in the same as point F in this way the results of the quartz

microbalance system will be more accurate in real time Point F is the final resting place for the laser

diode We use a Thor Labs Base with dimensions of ᴓ 9mm and ᴓ 56mm for two different size laser

diodes It just needs to be plugged in for easy installation

From figure 4-6 we know that the system needs signal system connections and because of the

change in temperature inside the chamber this could affect the functioning of the quartz microbalance so

we also need to install water tubes for cooling This is shown in figure 4-7 below

Fig 4-7 Diagram of Upper Cover Connections

In figure 4-8 we show the Feed through connections and their functions

Fig 4-8 Feed through Diagram

82

1 SQM-160 wire 5 Laser Connection 1 (Vin)

2 SQM-160 (G) 6 Laser Connection 2 (G)

3 K-Type-1 7 Laser Connection 3 (PD)

4 K-Type-2 8 Not In Use

The fully assembled chamber is shown in figure 4-9

Fig 4-9 Fully Assembled Chamber

422 Quartz Crystal Microbalance

For measuring the deposition on our target for coating we used the Inficon SQM-160 RateThickness

Monitor It is an easy to use instrument for measuring many types of thin-film coatings as shown in

figure 4-10

(a) Front Panel (b) Back Panel

Fig 4-10 Inficon SQM-160

83

Table 4-1 shows the technical specifications for this equipment

Number of sensors 2 Standard 4 additional optional

Sensor Frequency Range 40 MHz ~ 60 MHz

Reference Frequency Accuracy 002

Thickness Display Resolution 1 Aring

Thickness Resolution 015 Aring (Std) 0037 Aring (Hi Res)

Density of Stored Films 05-9999 gmcc

Tooling 10-399

Z-Factor 010-1000

Final Thickness 0000-9999k Aring

Measurement Period 15 to 2 sec

Simulation Mode Yes

Frequency Mode Yes

Rate Resolution 011 Arings

Dual Crystal Yes

Etch Mode Yes

Crystal Tooling 10-399

Crystal Fail Min Max 40 to 60 MHz 41 to 61 MHz

Power 100-120 200-240~plusmn10 nominal 20W

Operation Environment 0degC ~ 50degC

0 ~ 80 RH non-condensing

0 ~ 2000 meters

Class 1 Equipment

Pollution Degree 2

Rack Dimensions 885mm x 2127mm x 1969mm

Weight 27 kg

Table 4-1 Inficon SQM-160 RateThickness Monitor Specs

84

To the SQM-160 we need to connect an Oscillator We use the Sigma Instruments Remote Oscillator

Ser No 2 268 as shown in figure 4-11

Fig 4-11 Sigma Instruments Remote Oscillator

The connections diagram is shown in figure 4-12

Fig 4-12 SQM-160 Connections Diagram

85

423 Turbo Pump

For our experiments we used the Pfeiffer TCP 015 Electronic Drive Unit shown below in figure 4-13

Table 4-2 shows the technical specifications for this equipment

(a) Front Panel (b) Back Panel

Fig 4-13 Pfeiffer TCP 015 Electronic Drive

Connection Voltage (100V) 90-112

Mains Frequency 5060 Hz

Start-up Current 22 A

Nominal Frequency 1500 Hz

Rotation Speed 10V = 1500Hz plusmn2

Analog Output Current 10 V = 25 A plusmn 5

Rotation Speed Switchpoint 750 Hz

Works Setting 8 min

Permissible Ambient Temperature 0degC ~ 40degC

Dimensions Front Panel 1285mm x 1063mm

Insertion Length 227mm

Weight 27 Kg

Table 4-2 Pfeiffer TCP 015 Electronic Drive Specs

86

The connections diagram is shown in figure 4-14

Fig 4-14Connections Diagram for Pfeiffer TCP 015

To measure the pressure inside the chamber we use the Granville Phillips 375 Convectron Vacuum

Pressure Controller shown in figure 4-15

(a) Front Panel (b) Back Panel

Fig 4-15 Granville Phillips 375 Convectron

87

Its dimensions are shown in figure 4-16

Fig 4-16 Dimensions of Convectron

Table 4-3 shows the technical specifications for this equipment

Table 4-3 Granville Phillips 375 Convectron Vacuum Pressure Controller Specs

88

424 Multimeter

For our experiment we used the Keithley 2000 Digital Multimeter as shown in figure 4-17

(a) Front Panel (b) Back Panel

Fig 4-17 Keithley Model 2000 6-12-Digit Digital Multimeter

Its technical specifications are shown in table 4-4

Table 4-4 Keithley Model 2000 6-12-Digit Digital Multimeter Specs

89

43 Experiment Procedure

1 Connecting together the equipment and the chamber

(1) We first connect the resonator to the thickness monitor and connect the other side to the

chamber

(2) We now connect the flexible tubes to the turbo pump on one side and to the chamber on the

other

(3) We need to check that tubes are tightly connected to avoid any leaks in the vacuum pumping

process which will not allow us to get to our goal of Torr As shown in figure 4-18

(4) Connect the convectron to the system as shown in figure 4-19

Fig 4-18 checking for leaks using alcohol

Fig 4-19 Convectron attached to System

90

(5) Attach the clamps of the Multimeter to the bottom of the chamber as shown in figure 4-20

(6) Place the Quartz crystal in place

(7) Close tight vacuum chamber

(8) Connect all electrical appliances to power source

Fig 4-20 Multimeter Connections

2 Starting up the System

(1) We turn on all the devices as such Check all systems are ready to function Reset all values

that might be left over from previous tests

(2) Start the thickness monitor and set all values for this experiment In our case we got to testing

the system but not actual coating So we used the simulation mode of the thickness monitor as

shown in figure 4-21

Fig 4-21 Simulation Mode

91

(3) Start the turbo pump Make sure the lid on the vacuum chamber is tightly closed

(4) Start convectron and record initial pressure

(5) Start Multimeter and record initial current

3 Coating Process

(1) If we have the deposition material inside the filament boat the power source for the high

current must be started as well

(2) Record all initial values for thickness current pressure

(3) For an ideal experiment we need a thickness of around 101 nm a pressure of Torr and

a current of 300 A

44 Results

From previous experiments we have shown that we can turn a LED into a laser by means of AR

Coating In figure 4-22 shown below we can compare the actual results of a Diode before and after AR

coating From the blue line we can see that when the diode is at a current of 15mA its light will change

from LED to laser and if we look at the red line its critical current is around 30 to 35 mA

Fig 4-22 AR Coating Comparison for Laser Diodes

This means that the light emitted is not as strong as if the diode had been coated because inside the

chamber there must be some excitation first so the reflectivity of both sides inside the diode must be high

So because of the coating in one of the sides we have opened a door and let the light come out so the

critical current is risen as such and will be higher value than that of before the coating

92

In the following figures we can see the difference between before and after coating in a material The

thickness is around 1016 nm for this material

Fig 4-23 Before Coating

Fig 4-24 After Coating

93

Chapter 5 CONCLUSIONS AND RECOMMENDATIONS

51 Conclusions

For the first part of this independent study taking into consideration the data that came out of our

research and that sent by the provider we can say

1 SUM 23 after heat treatment will unexpectedly develop cracking in the middle of the tensile

testing process and suddenly break

2 Itrsquos possible that in the process of heat treatment to the SUM 23 material the treatment was not

uniform and this will create a pre-loaded moment force on one side that pushes on the other side

of the specimen resulting in material deformation

3 In the process of attaching the strain gauges to the materials it is very easy to make errors due to

poor adhesion or sudden removal in the tensile testing process

For our second part of the independent study the following can be made

1 At the beginning of this independent study we had no idea what Bose-Einstein Condensate was

or what was its purpose After much literature we finally comprehended the basic principles to

put into practice for our research

2 Our systemrsquos basic working principles and equipmentrsquos complexity are a little difficult to grasp

but hopefully we were able to understand enough of it

3 Theoretically from relation between the power and current we can know the advantages and

disadvantages of AR Coating

4 We were able to assemble the system and run test on its functions Even though we were able to

do this there is still much more work left to do with this system

52 Recommendations

For the Tensile Testing the following can be said

1 Ask the provider to check on the process of heat treatment on the SUM 23 material and give

them the information we have gathered through our test so they can correct for the mechanical

properties found if any change is needed

2 To avoid the problem of the inaccuracy of the poor adhesion of strain gauges we can attach

multiple strain gauges to the same one specimen so as to correlate data and improve our results

For the AR Coating the following can be said

1 We need to make sure that there are no physical defects on the main body of the chamber so as to

achieve maximum efficiency in the vacuum process If there was then the vacuum will arrive to

certain point and then start to decrease

2 It would be preferable to add some sort of visual aid that will allow the user to check the inside of

the chamber without actually opening it This will help us determine at what times we should

manipulate the current to better evaporate the substrate

94

REFERENCES

[1] A L Window Strain Gauge Technology Elsevier Applied Science London and New York 2nd

Edition 1992

[2] CC Perry and HR Lissner Strain Gauge Primer McGraw-Hill Book Co Inc New York 1955

[3] James W Dally William F Riley McGraw-Hill 1978

[4] University of Colorado Boulder BEC - What is it and where did the idea come from

httpwwwcoloradoeduphysics2000becwhat_is_ithtml

[5] Ultraslow Light amp Bose-Einstein Condensates Two-way Control with Coherent Light amp Atom

Fields Harvard Hau Lab Dr Lene Vestergaard Hau Optics amp Photonics News 16 1995

[6] The Art of Taming Light Ultra-slow and Stopped Light Harvard Hau Lab Dr Lene

Vestergaard Hau Europhysics News 2004

[7] Nonlinear Optics Shocking Superfluids Harvard Hau Lab Dr Lene Vestergaard Hau Nature

Physics 2007

[8] Model P3 Strain Indicator and Recorder Instruction Manual Vishay Micro-Measurements 2005

[9] Granville-Phillips Series 375 Convectron Vacuum Gauge Controller Instruction Manual Brooks

Automation 2008

[10] Effect of Film Thickness on the Validity of the Sauerbrey Equation for Hydrated Polyelectrolyte

Films Vogt Lin Wu White 2004

[11] Quartz Crystal Microbalance Study of DNA Immobilization and Hybridization for DNA Sensor

Development Chang Zhao 2008

[12] Installation of Strain Gages with SR-4 PrecoatAdhesive Vishay Micro-Measurements 2005

[13] Strain Gauge Measurement ndash A Tutorial National Instruments 1998

[14] Correlation between Vickers Hardness Number and Yield Stress of Cold-Formed Products

Yavuz Tekkaya

[15] httpsenwikipediaorg

Page 69: PC Hinge Materials Testing and AR Laser Diode Coating

69

Cut-Off Area

(a)

(b)

Fig 3-22 Cut-Off Area of SUM 43 (a) 1 Round Bar and (b) 5 Round Bar

70

SUM 43 Nickel Round Bar

Fig 3-23 SUM 43 Nickel Material

Number 4 5

Hardness(HRB) 51 50

Yield Stress (MPa) 1580 1544

Tensile Strength (MPa) 1639 1625

Poissonrsquos Ratio 03 028

Youngrsquos Modulus (GPa) 194 201

Cut-off Area Shrinking () 1697 137

Elongation () 376 265

Table 3-9 Mechanical Properties of SUM 43 Nickel

71

Stress-Strain Diagrams

(a)

(b)

Fig 3-24 Stress-Strain Diagrams for (a) 4 Round Bar and (b) 5 Round Bar

72

Cut-Off Area

(a)

(b)

Fig 3-25 Cut-Off Area of (a) 4 Round Bar and (b) 5 Round Bar

73

SUM 43 Black Surface Material

Fig 3-26 SUM 43 Black Surface Material

Number 3 5

Hardness(HRB) 56 56

Yield Stress (MPa) 1416 1361

Tensile Strength (MPa) 1591 1402

Poissonrsquos Ratio 029 031

Youngrsquos Modulus (GPa) 200 202

Cut-off Area Shrinking () 139 124

Elongation () 24 24

Table 3-10 Mechanical Properties of SUM 43 Black Surface Material

74

Stress-Strain Diagrams

0 2 4 6 8 10 12 14

-200

0

200

400

600

800

1000

1200

1400

1600

1800

應力 (MPa)

應變()

(a)

0 2 4 6 8 10

-200

0

200

400

600

800

1000

1200

1400

1600

應力

(MPa)

位移 ()

(b)

Fig 3-27 Stress-Strain Diagrams for (a) 3 Round Bar and (b) 5 Round Bar

(Note These curves were formulated using Visual Solutions Inc VisSim Software)

75

Cut-Off Area

(a)

(b)

Fig 3-28 Cut-Off Area of (a) 3 Round Bar and (b) 5 Round Bar

76

The force value (N) was retrieved from the Universal Testing Machine

The Poissonrsquos Ratio (ε) is calculated as

ε =

the values for the Poissonrsquos Ratio are in average around 0297

The Youngrsquos Modulus (E) is calculated as

E =

Where

Stress =

Cross-sectional Area =

where D is the Diameter

The value for D was in average around 1258 mm

The values shown by the computer because there is Slippage phenomena between the Clamp and the

specimen will not be taken into consideration for the elongation strain and Youngrsquos modulus and we will

refer to the values that we have meticulously calculated

77

Chapter 4 AR COATING IN DEPTH

41 Experimentrsquos Purpose and Principles

By means of a vacuum chamber and several other instruments we intend to apply Anti-Reflective

Coating using deposition process to a laser diode and in this way reduce its refraction so as to make it

lose less light in the process of amplification and we can control certain wavelengths we want produced

for certain desired applications in our case we are attempting to re-create a Bose-Einstein Condensate

An optimal BEC apparatus is shown in figure 4-1

Fig 4-1 BEC Apparatus

The main point of this experiment is to build a vacuum chamber system attach all the instrumentation

needed (Vacuum pump deposition meter and voltmeter) and use it to apply AR coating to a laser diode

After we have accomplished the AR coating other team will be in charge of designing the BEC apparatus

and use the results of our research

78

42 Experimentrsquos Equipment

421 Vacuum Chamber

For this research we designed a vacuum chamber whose main body is shown in figure 4-2 Its

dimensions are

Width 240 mm

Length 240 mm

Height 200 mm

Outer Diameter 4 in

Inner Diameter 15 in

Fig 4-2 Vacuum Chamber Main Body

The chamber is made up of 6 pass ways pass way A is the connection with the Laser Deposition

Equipment pass way B is the connection with the Turbo Pump and pass way C is for the connection with

the Deposition Source

A

C

B

79

Pass way C is for the deposition source as mentioned above This is a system where a thermal

resistance is heated by passing a high current through it which heats up a filament boat (made of tungsten)

where the material to be evaporated is place We control the temperature as such that the material will

evaporate and the heat will not cause the filament boat to crack

Because P = Isup2 R (where P is power I is current and R is resistance) to avoid the current to flow

where it is not desired we decided that the material for the Thermocouple shown in figure 4-3 should be

Copper ᴓ 63 mm We choose it that way because Copper has very good heat dissipation characteristics

and the resistance value is low It can reduce the value of the current enough to make the thermocouple to

create heat

Fig 4-3 Thermocouple

To the thermocouple we attach the tungsten filament boat We need to take notice of materials to be

used in this design because when using high current the tungsten filament boar will heat up and so the

material must be able to keep up with the heating potential of tungsten and has a low coefficient of heat

dissipation to avoid the tungsten to fail when heating up and therefore not evaporating Considering all

this we decide to use Stainless Steel

Because this clamp will be assembled inside the chamber after many revisions it was determined it

will have the shape shown in figure 4-4

Fig 4-4 Filament Boat Clamp Design

80

For the tungsten filament boat we bought the product from a distributor The dimensions are

Length 100 mm

Width 10 mm

Height 1 mm

Our thermocouple is 15 in but the pass way C is 4 in so we need to attach a Flange that connects

15in to 4in Because these specifications are quite difficult to achieve by Milling we had to use

electrical wire cutting

For the laser clamping system where the laser that is going to be AR coated will be placed will be

connected to pass way A the assembly is shown in figure 4-5 below

Fig 4-5 Cover Assembly

For this design we used an O-ring instead of a gasket so as to save time The design of the assembly

where the laser will be placed is shown in figure 4-6

Fig 4-6 Upper Cover Inner Assembly

D

E

F

81

Point D is the plate in the assembly where the laser diode will be fixed Because of the easy

processing we decide to use Aluminum and it is screwed to the top cover Point E is the connection for

the Quartz crystal resonator and it is designed in the same as point F in this way the results of the quartz

microbalance system will be more accurate in real time Point F is the final resting place for the laser

diode We use a Thor Labs Base with dimensions of ᴓ 9mm and ᴓ 56mm for two different size laser

diodes It just needs to be plugged in for easy installation

From figure 4-6 we know that the system needs signal system connections and because of the

change in temperature inside the chamber this could affect the functioning of the quartz microbalance so

we also need to install water tubes for cooling This is shown in figure 4-7 below

Fig 4-7 Diagram of Upper Cover Connections

In figure 4-8 we show the Feed through connections and their functions

Fig 4-8 Feed through Diagram

82

1 SQM-160 wire 5 Laser Connection 1 (Vin)

2 SQM-160 (G) 6 Laser Connection 2 (G)

3 K-Type-1 7 Laser Connection 3 (PD)

4 K-Type-2 8 Not In Use

The fully assembled chamber is shown in figure 4-9

Fig 4-9 Fully Assembled Chamber

422 Quartz Crystal Microbalance

For measuring the deposition on our target for coating we used the Inficon SQM-160 RateThickness

Monitor It is an easy to use instrument for measuring many types of thin-film coatings as shown in

figure 4-10

(a) Front Panel (b) Back Panel

Fig 4-10 Inficon SQM-160

83

Table 4-1 shows the technical specifications for this equipment

Number of sensors 2 Standard 4 additional optional

Sensor Frequency Range 40 MHz ~ 60 MHz

Reference Frequency Accuracy 002

Thickness Display Resolution 1 Aring

Thickness Resolution 015 Aring (Std) 0037 Aring (Hi Res)

Density of Stored Films 05-9999 gmcc

Tooling 10-399

Z-Factor 010-1000

Final Thickness 0000-9999k Aring

Measurement Period 15 to 2 sec

Simulation Mode Yes

Frequency Mode Yes

Rate Resolution 011 Arings

Dual Crystal Yes

Etch Mode Yes

Crystal Tooling 10-399

Crystal Fail Min Max 40 to 60 MHz 41 to 61 MHz

Power 100-120 200-240~plusmn10 nominal 20W

Operation Environment 0degC ~ 50degC

0 ~ 80 RH non-condensing

0 ~ 2000 meters

Class 1 Equipment

Pollution Degree 2

Rack Dimensions 885mm x 2127mm x 1969mm

Weight 27 kg

Table 4-1 Inficon SQM-160 RateThickness Monitor Specs

84

To the SQM-160 we need to connect an Oscillator We use the Sigma Instruments Remote Oscillator

Ser No 2 268 as shown in figure 4-11

Fig 4-11 Sigma Instruments Remote Oscillator

The connections diagram is shown in figure 4-12

Fig 4-12 SQM-160 Connections Diagram

85

423 Turbo Pump

For our experiments we used the Pfeiffer TCP 015 Electronic Drive Unit shown below in figure 4-13

Table 4-2 shows the technical specifications for this equipment

(a) Front Panel (b) Back Panel

Fig 4-13 Pfeiffer TCP 015 Electronic Drive

Connection Voltage (100V) 90-112

Mains Frequency 5060 Hz

Start-up Current 22 A

Nominal Frequency 1500 Hz

Rotation Speed 10V = 1500Hz plusmn2

Analog Output Current 10 V = 25 A plusmn 5

Rotation Speed Switchpoint 750 Hz

Works Setting 8 min

Permissible Ambient Temperature 0degC ~ 40degC

Dimensions Front Panel 1285mm x 1063mm

Insertion Length 227mm

Weight 27 Kg

Table 4-2 Pfeiffer TCP 015 Electronic Drive Specs

86

The connections diagram is shown in figure 4-14

Fig 4-14Connections Diagram for Pfeiffer TCP 015

To measure the pressure inside the chamber we use the Granville Phillips 375 Convectron Vacuum

Pressure Controller shown in figure 4-15

(a) Front Panel (b) Back Panel

Fig 4-15 Granville Phillips 375 Convectron

87

Its dimensions are shown in figure 4-16

Fig 4-16 Dimensions of Convectron

Table 4-3 shows the technical specifications for this equipment

Table 4-3 Granville Phillips 375 Convectron Vacuum Pressure Controller Specs

88

424 Multimeter

For our experiment we used the Keithley 2000 Digital Multimeter as shown in figure 4-17

(a) Front Panel (b) Back Panel

Fig 4-17 Keithley Model 2000 6-12-Digit Digital Multimeter

Its technical specifications are shown in table 4-4

Table 4-4 Keithley Model 2000 6-12-Digit Digital Multimeter Specs

89

43 Experiment Procedure

1 Connecting together the equipment and the chamber

(1) We first connect the resonator to the thickness monitor and connect the other side to the

chamber

(2) We now connect the flexible tubes to the turbo pump on one side and to the chamber on the

other

(3) We need to check that tubes are tightly connected to avoid any leaks in the vacuum pumping

process which will not allow us to get to our goal of Torr As shown in figure 4-18

(4) Connect the convectron to the system as shown in figure 4-19

Fig 4-18 checking for leaks using alcohol

Fig 4-19 Convectron attached to System

90

(5) Attach the clamps of the Multimeter to the bottom of the chamber as shown in figure 4-20

(6) Place the Quartz crystal in place

(7) Close tight vacuum chamber

(8) Connect all electrical appliances to power source

Fig 4-20 Multimeter Connections

2 Starting up the System

(1) We turn on all the devices as such Check all systems are ready to function Reset all values

that might be left over from previous tests

(2) Start the thickness monitor and set all values for this experiment In our case we got to testing

the system but not actual coating So we used the simulation mode of the thickness monitor as

shown in figure 4-21

Fig 4-21 Simulation Mode

91

(3) Start the turbo pump Make sure the lid on the vacuum chamber is tightly closed

(4) Start convectron and record initial pressure

(5) Start Multimeter and record initial current

3 Coating Process

(1) If we have the deposition material inside the filament boat the power source for the high

current must be started as well

(2) Record all initial values for thickness current pressure

(3) For an ideal experiment we need a thickness of around 101 nm a pressure of Torr and

a current of 300 A

44 Results

From previous experiments we have shown that we can turn a LED into a laser by means of AR

Coating In figure 4-22 shown below we can compare the actual results of a Diode before and after AR

coating From the blue line we can see that when the diode is at a current of 15mA its light will change

from LED to laser and if we look at the red line its critical current is around 30 to 35 mA

Fig 4-22 AR Coating Comparison for Laser Diodes

This means that the light emitted is not as strong as if the diode had been coated because inside the

chamber there must be some excitation first so the reflectivity of both sides inside the diode must be high

So because of the coating in one of the sides we have opened a door and let the light come out so the

critical current is risen as such and will be higher value than that of before the coating

92

In the following figures we can see the difference between before and after coating in a material The

thickness is around 1016 nm for this material

Fig 4-23 Before Coating

Fig 4-24 After Coating

93

Chapter 5 CONCLUSIONS AND RECOMMENDATIONS

51 Conclusions

For the first part of this independent study taking into consideration the data that came out of our

research and that sent by the provider we can say

1 SUM 23 after heat treatment will unexpectedly develop cracking in the middle of the tensile

testing process and suddenly break

2 Itrsquos possible that in the process of heat treatment to the SUM 23 material the treatment was not

uniform and this will create a pre-loaded moment force on one side that pushes on the other side

of the specimen resulting in material deformation

3 In the process of attaching the strain gauges to the materials it is very easy to make errors due to

poor adhesion or sudden removal in the tensile testing process

For our second part of the independent study the following can be made

1 At the beginning of this independent study we had no idea what Bose-Einstein Condensate was

or what was its purpose After much literature we finally comprehended the basic principles to

put into practice for our research

2 Our systemrsquos basic working principles and equipmentrsquos complexity are a little difficult to grasp

but hopefully we were able to understand enough of it

3 Theoretically from relation between the power and current we can know the advantages and

disadvantages of AR Coating

4 We were able to assemble the system and run test on its functions Even though we were able to

do this there is still much more work left to do with this system

52 Recommendations

For the Tensile Testing the following can be said

1 Ask the provider to check on the process of heat treatment on the SUM 23 material and give

them the information we have gathered through our test so they can correct for the mechanical

properties found if any change is needed

2 To avoid the problem of the inaccuracy of the poor adhesion of strain gauges we can attach

multiple strain gauges to the same one specimen so as to correlate data and improve our results

For the AR Coating the following can be said

1 We need to make sure that there are no physical defects on the main body of the chamber so as to

achieve maximum efficiency in the vacuum process If there was then the vacuum will arrive to

certain point and then start to decrease

2 It would be preferable to add some sort of visual aid that will allow the user to check the inside of

the chamber without actually opening it This will help us determine at what times we should

manipulate the current to better evaporate the substrate

94

REFERENCES

[1] A L Window Strain Gauge Technology Elsevier Applied Science London and New York 2nd

Edition 1992

[2] CC Perry and HR Lissner Strain Gauge Primer McGraw-Hill Book Co Inc New York 1955

[3] James W Dally William F Riley McGraw-Hill 1978

[4] University of Colorado Boulder BEC - What is it and where did the idea come from

httpwwwcoloradoeduphysics2000becwhat_is_ithtml

[5] Ultraslow Light amp Bose-Einstein Condensates Two-way Control with Coherent Light amp Atom

Fields Harvard Hau Lab Dr Lene Vestergaard Hau Optics amp Photonics News 16 1995

[6] The Art of Taming Light Ultra-slow and Stopped Light Harvard Hau Lab Dr Lene

Vestergaard Hau Europhysics News 2004

[7] Nonlinear Optics Shocking Superfluids Harvard Hau Lab Dr Lene Vestergaard Hau Nature

Physics 2007

[8] Model P3 Strain Indicator and Recorder Instruction Manual Vishay Micro-Measurements 2005

[9] Granville-Phillips Series 375 Convectron Vacuum Gauge Controller Instruction Manual Brooks

Automation 2008

[10] Effect of Film Thickness on the Validity of the Sauerbrey Equation for Hydrated Polyelectrolyte

Films Vogt Lin Wu White 2004

[11] Quartz Crystal Microbalance Study of DNA Immobilization and Hybridization for DNA Sensor

Development Chang Zhao 2008

[12] Installation of Strain Gages with SR-4 PrecoatAdhesive Vishay Micro-Measurements 2005

[13] Strain Gauge Measurement ndash A Tutorial National Instruments 1998

[14] Correlation between Vickers Hardness Number and Yield Stress of Cold-Formed Products

Yavuz Tekkaya

[15] httpsenwikipediaorg

Page 70: PC Hinge Materials Testing and AR Laser Diode Coating

70

SUM 43 Nickel Round Bar

Fig 3-23 SUM 43 Nickel Material

Number 4 5

Hardness(HRB) 51 50

Yield Stress (MPa) 1580 1544

Tensile Strength (MPa) 1639 1625

Poissonrsquos Ratio 03 028

Youngrsquos Modulus (GPa) 194 201

Cut-off Area Shrinking () 1697 137

Elongation () 376 265

Table 3-9 Mechanical Properties of SUM 43 Nickel

71

Stress-Strain Diagrams

(a)

(b)

Fig 3-24 Stress-Strain Diagrams for (a) 4 Round Bar and (b) 5 Round Bar

72

Cut-Off Area

(a)

(b)

Fig 3-25 Cut-Off Area of (a) 4 Round Bar and (b) 5 Round Bar

73

SUM 43 Black Surface Material

Fig 3-26 SUM 43 Black Surface Material

Number 3 5

Hardness(HRB) 56 56

Yield Stress (MPa) 1416 1361

Tensile Strength (MPa) 1591 1402

Poissonrsquos Ratio 029 031

Youngrsquos Modulus (GPa) 200 202

Cut-off Area Shrinking () 139 124

Elongation () 24 24

Table 3-10 Mechanical Properties of SUM 43 Black Surface Material

74

Stress-Strain Diagrams

0 2 4 6 8 10 12 14

-200

0

200

400

600

800

1000

1200

1400

1600

1800

應力 (MPa)

應變()

(a)

0 2 4 6 8 10

-200

0

200

400

600

800

1000

1200

1400

1600

應力

(MPa)

位移 ()

(b)

Fig 3-27 Stress-Strain Diagrams for (a) 3 Round Bar and (b) 5 Round Bar

(Note These curves were formulated using Visual Solutions Inc VisSim Software)

75

Cut-Off Area

(a)

(b)

Fig 3-28 Cut-Off Area of (a) 3 Round Bar and (b) 5 Round Bar

76

The force value (N) was retrieved from the Universal Testing Machine

The Poissonrsquos Ratio (ε) is calculated as

ε =

the values for the Poissonrsquos Ratio are in average around 0297

The Youngrsquos Modulus (E) is calculated as

E =

Where

Stress =

Cross-sectional Area =

where D is the Diameter

The value for D was in average around 1258 mm

The values shown by the computer because there is Slippage phenomena between the Clamp and the

specimen will not be taken into consideration for the elongation strain and Youngrsquos modulus and we will

refer to the values that we have meticulously calculated

77

Chapter 4 AR COATING IN DEPTH

41 Experimentrsquos Purpose and Principles

By means of a vacuum chamber and several other instruments we intend to apply Anti-Reflective

Coating using deposition process to a laser diode and in this way reduce its refraction so as to make it

lose less light in the process of amplification and we can control certain wavelengths we want produced

for certain desired applications in our case we are attempting to re-create a Bose-Einstein Condensate

An optimal BEC apparatus is shown in figure 4-1

Fig 4-1 BEC Apparatus

The main point of this experiment is to build a vacuum chamber system attach all the instrumentation

needed (Vacuum pump deposition meter and voltmeter) and use it to apply AR coating to a laser diode

After we have accomplished the AR coating other team will be in charge of designing the BEC apparatus

and use the results of our research

78

42 Experimentrsquos Equipment

421 Vacuum Chamber

For this research we designed a vacuum chamber whose main body is shown in figure 4-2 Its

dimensions are

Width 240 mm

Length 240 mm

Height 200 mm

Outer Diameter 4 in

Inner Diameter 15 in

Fig 4-2 Vacuum Chamber Main Body

The chamber is made up of 6 pass ways pass way A is the connection with the Laser Deposition

Equipment pass way B is the connection with the Turbo Pump and pass way C is for the connection with

the Deposition Source

A

C

B

79

Pass way C is for the deposition source as mentioned above This is a system where a thermal

resistance is heated by passing a high current through it which heats up a filament boat (made of tungsten)

where the material to be evaporated is place We control the temperature as such that the material will

evaporate and the heat will not cause the filament boat to crack

Because P = Isup2 R (where P is power I is current and R is resistance) to avoid the current to flow

where it is not desired we decided that the material for the Thermocouple shown in figure 4-3 should be

Copper ᴓ 63 mm We choose it that way because Copper has very good heat dissipation characteristics

and the resistance value is low It can reduce the value of the current enough to make the thermocouple to

create heat

Fig 4-3 Thermocouple

To the thermocouple we attach the tungsten filament boat We need to take notice of materials to be

used in this design because when using high current the tungsten filament boar will heat up and so the

material must be able to keep up with the heating potential of tungsten and has a low coefficient of heat

dissipation to avoid the tungsten to fail when heating up and therefore not evaporating Considering all

this we decide to use Stainless Steel

Because this clamp will be assembled inside the chamber after many revisions it was determined it

will have the shape shown in figure 4-4

Fig 4-4 Filament Boat Clamp Design

80

For the tungsten filament boat we bought the product from a distributor The dimensions are

Length 100 mm

Width 10 mm

Height 1 mm

Our thermocouple is 15 in but the pass way C is 4 in so we need to attach a Flange that connects

15in to 4in Because these specifications are quite difficult to achieve by Milling we had to use

electrical wire cutting

For the laser clamping system where the laser that is going to be AR coated will be placed will be

connected to pass way A the assembly is shown in figure 4-5 below

Fig 4-5 Cover Assembly

For this design we used an O-ring instead of a gasket so as to save time The design of the assembly

where the laser will be placed is shown in figure 4-6

Fig 4-6 Upper Cover Inner Assembly

D

E

F

81

Point D is the plate in the assembly where the laser diode will be fixed Because of the easy

processing we decide to use Aluminum and it is screwed to the top cover Point E is the connection for

the Quartz crystal resonator and it is designed in the same as point F in this way the results of the quartz

microbalance system will be more accurate in real time Point F is the final resting place for the laser

diode We use a Thor Labs Base with dimensions of ᴓ 9mm and ᴓ 56mm for two different size laser

diodes It just needs to be plugged in for easy installation

From figure 4-6 we know that the system needs signal system connections and because of the

change in temperature inside the chamber this could affect the functioning of the quartz microbalance so

we also need to install water tubes for cooling This is shown in figure 4-7 below

Fig 4-7 Diagram of Upper Cover Connections

In figure 4-8 we show the Feed through connections and their functions

Fig 4-8 Feed through Diagram

82

1 SQM-160 wire 5 Laser Connection 1 (Vin)

2 SQM-160 (G) 6 Laser Connection 2 (G)

3 K-Type-1 7 Laser Connection 3 (PD)

4 K-Type-2 8 Not In Use

The fully assembled chamber is shown in figure 4-9

Fig 4-9 Fully Assembled Chamber

422 Quartz Crystal Microbalance

For measuring the deposition on our target for coating we used the Inficon SQM-160 RateThickness

Monitor It is an easy to use instrument for measuring many types of thin-film coatings as shown in

figure 4-10

(a) Front Panel (b) Back Panel

Fig 4-10 Inficon SQM-160

83

Table 4-1 shows the technical specifications for this equipment

Number of sensors 2 Standard 4 additional optional

Sensor Frequency Range 40 MHz ~ 60 MHz

Reference Frequency Accuracy 002

Thickness Display Resolution 1 Aring

Thickness Resolution 015 Aring (Std) 0037 Aring (Hi Res)

Density of Stored Films 05-9999 gmcc

Tooling 10-399

Z-Factor 010-1000

Final Thickness 0000-9999k Aring

Measurement Period 15 to 2 sec

Simulation Mode Yes

Frequency Mode Yes

Rate Resolution 011 Arings

Dual Crystal Yes

Etch Mode Yes

Crystal Tooling 10-399

Crystal Fail Min Max 40 to 60 MHz 41 to 61 MHz

Power 100-120 200-240~plusmn10 nominal 20W

Operation Environment 0degC ~ 50degC

0 ~ 80 RH non-condensing

0 ~ 2000 meters

Class 1 Equipment

Pollution Degree 2

Rack Dimensions 885mm x 2127mm x 1969mm

Weight 27 kg

Table 4-1 Inficon SQM-160 RateThickness Monitor Specs

84

To the SQM-160 we need to connect an Oscillator We use the Sigma Instruments Remote Oscillator

Ser No 2 268 as shown in figure 4-11

Fig 4-11 Sigma Instruments Remote Oscillator

The connections diagram is shown in figure 4-12

Fig 4-12 SQM-160 Connections Diagram

85

423 Turbo Pump

For our experiments we used the Pfeiffer TCP 015 Electronic Drive Unit shown below in figure 4-13

Table 4-2 shows the technical specifications for this equipment

(a) Front Panel (b) Back Panel

Fig 4-13 Pfeiffer TCP 015 Electronic Drive

Connection Voltage (100V) 90-112

Mains Frequency 5060 Hz

Start-up Current 22 A

Nominal Frequency 1500 Hz

Rotation Speed 10V = 1500Hz plusmn2

Analog Output Current 10 V = 25 A plusmn 5

Rotation Speed Switchpoint 750 Hz

Works Setting 8 min

Permissible Ambient Temperature 0degC ~ 40degC

Dimensions Front Panel 1285mm x 1063mm

Insertion Length 227mm

Weight 27 Kg

Table 4-2 Pfeiffer TCP 015 Electronic Drive Specs

86

The connections diagram is shown in figure 4-14

Fig 4-14Connections Diagram for Pfeiffer TCP 015

To measure the pressure inside the chamber we use the Granville Phillips 375 Convectron Vacuum

Pressure Controller shown in figure 4-15

(a) Front Panel (b) Back Panel

Fig 4-15 Granville Phillips 375 Convectron

87

Its dimensions are shown in figure 4-16

Fig 4-16 Dimensions of Convectron

Table 4-3 shows the technical specifications for this equipment

Table 4-3 Granville Phillips 375 Convectron Vacuum Pressure Controller Specs

88

424 Multimeter

For our experiment we used the Keithley 2000 Digital Multimeter as shown in figure 4-17

(a) Front Panel (b) Back Panel

Fig 4-17 Keithley Model 2000 6-12-Digit Digital Multimeter

Its technical specifications are shown in table 4-4

Table 4-4 Keithley Model 2000 6-12-Digit Digital Multimeter Specs

89

43 Experiment Procedure

1 Connecting together the equipment and the chamber

(1) We first connect the resonator to the thickness monitor and connect the other side to the

chamber

(2) We now connect the flexible tubes to the turbo pump on one side and to the chamber on the

other

(3) We need to check that tubes are tightly connected to avoid any leaks in the vacuum pumping

process which will not allow us to get to our goal of Torr As shown in figure 4-18

(4) Connect the convectron to the system as shown in figure 4-19

Fig 4-18 checking for leaks using alcohol

Fig 4-19 Convectron attached to System

90

(5) Attach the clamps of the Multimeter to the bottom of the chamber as shown in figure 4-20

(6) Place the Quartz crystal in place

(7) Close tight vacuum chamber

(8) Connect all electrical appliances to power source

Fig 4-20 Multimeter Connections

2 Starting up the System

(1) We turn on all the devices as such Check all systems are ready to function Reset all values

that might be left over from previous tests

(2) Start the thickness monitor and set all values for this experiment In our case we got to testing

the system but not actual coating So we used the simulation mode of the thickness monitor as

shown in figure 4-21

Fig 4-21 Simulation Mode

91

(3) Start the turbo pump Make sure the lid on the vacuum chamber is tightly closed

(4) Start convectron and record initial pressure

(5) Start Multimeter and record initial current

3 Coating Process

(1) If we have the deposition material inside the filament boat the power source for the high

current must be started as well

(2) Record all initial values for thickness current pressure

(3) For an ideal experiment we need a thickness of around 101 nm a pressure of Torr and

a current of 300 A

44 Results

From previous experiments we have shown that we can turn a LED into a laser by means of AR

Coating In figure 4-22 shown below we can compare the actual results of a Diode before and after AR

coating From the blue line we can see that when the diode is at a current of 15mA its light will change

from LED to laser and if we look at the red line its critical current is around 30 to 35 mA

Fig 4-22 AR Coating Comparison for Laser Diodes

This means that the light emitted is not as strong as if the diode had been coated because inside the

chamber there must be some excitation first so the reflectivity of both sides inside the diode must be high

So because of the coating in one of the sides we have opened a door and let the light come out so the

critical current is risen as such and will be higher value than that of before the coating

92

In the following figures we can see the difference between before and after coating in a material The

thickness is around 1016 nm for this material

Fig 4-23 Before Coating

Fig 4-24 After Coating

93

Chapter 5 CONCLUSIONS AND RECOMMENDATIONS

51 Conclusions

For the first part of this independent study taking into consideration the data that came out of our

research and that sent by the provider we can say

1 SUM 23 after heat treatment will unexpectedly develop cracking in the middle of the tensile

testing process and suddenly break

2 Itrsquos possible that in the process of heat treatment to the SUM 23 material the treatment was not

uniform and this will create a pre-loaded moment force on one side that pushes on the other side

of the specimen resulting in material deformation

3 In the process of attaching the strain gauges to the materials it is very easy to make errors due to

poor adhesion or sudden removal in the tensile testing process

For our second part of the independent study the following can be made

1 At the beginning of this independent study we had no idea what Bose-Einstein Condensate was

or what was its purpose After much literature we finally comprehended the basic principles to

put into practice for our research

2 Our systemrsquos basic working principles and equipmentrsquos complexity are a little difficult to grasp

but hopefully we were able to understand enough of it

3 Theoretically from relation between the power and current we can know the advantages and

disadvantages of AR Coating

4 We were able to assemble the system and run test on its functions Even though we were able to

do this there is still much more work left to do with this system

52 Recommendations

For the Tensile Testing the following can be said

1 Ask the provider to check on the process of heat treatment on the SUM 23 material and give

them the information we have gathered through our test so they can correct for the mechanical

properties found if any change is needed

2 To avoid the problem of the inaccuracy of the poor adhesion of strain gauges we can attach

multiple strain gauges to the same one specimen so as to correlate data and improve our results

For the AR Coating the following can be said

1 We need to make sure that there are no physical defects on the main body of the chamber so as to

achieve maximum efficiency in the vacuum process If there was then the vacuum will arrive to

certain point and then start to decrease

2 It would be preferable to add some sort of visual aid that will allow the user to check the inside of

the chamber without actually opening it This will help us determine at what times we should

manipulate the current to better evaporate the substrate

94

REFERENCES

[1] A L Window Strain Gauge Technology Elsevier Applied Science London and New York 2nd

Edition 1992

[2] CC Perry and HR Lissner Strain Gauge Primer McGraw-Hill Book Co Inc New York 1955

[3] James W Dally William F Riley McGraw-Hill 1978

[4] University of Colorado Boulder BEC - What is it and where did the idea come from

httpwwwcoloradoeduphysics2000becwhat_is_ithtml

[5] Ultraslow Light amp Bose-Einstein Condensates Two-way Control with Coherent Light amp Atom

Fields Harvard Hau Lab Dr Lene Vestergaard Hau Optics amp Photonics News 16 1995

[6] The Art of Taming Light Ultra-slow and Stopped Light Harvard Hau Lab Dr Lene

Vestergaard Hau Europhysics News 2004

[7] Nonlinear Optics Shocking Superfluids Harvard Hau Lab Dr Lene Vestergaard Hau Nature

Physics 2007

[8] Model P3 Strain Indicator and Recorder Instruction Manual Vishay Micro-Measurements 2005

[9] Granville-Phillips Series 375 Convectron Vacuum Gauge Controller Instruction Manual Brooks

Automation 2008

[10] Effect of Film Thickness on the Validity of the Sauerbrey Equation for Hydrated Polyelectrolyte

Films Vogt Lin Wu White 2004

[11] Quartz Crystal Microbalance Study of DNA Immobilization and Hybridization for DNA Sensor

Development Chang Zhao 2008

[12] Installation of Strain Gages with SR-4 PrecoatAdhesive Vishay Micro-Measurements 2005

[13] Strain Gauge Measurement ndash A Tutorial National Instruments 1998

[14] Correlation between Vickers Hardness Number and Yield Stress of Cold-Formed Products

Yavuz Tekkaya

[15] httpsenwikipediaorg

Page 71: PC Hinge Materials Testing and AR Laser Diode Coating

71

Stress-Strain Diagrams

(a)

(b)

Fig 3-24 Stress-Strain Diagrams for (a) 4 Round Bar and (b) 5 Round Bar

72

Cut-Off Area

(a)

(b)

Fig 3-25 Cut-Off Area of (a) 4 Round Bar and (b) 5 Round Bar

73

SUM 43 Black Surface Material

Fig 3-26 SUM 43 Black Surface Material

Number 3 5

Hardness(HRB) 56 56

Yield Stress (MPa) 1416 1361

Tensile Strength (MPa) 1591 1402

Poissonrsquos Ratio 029 031

Youngrsquos Modulus (GPa) 200 202

Cut-off Area Shrinking () 139 124

Elongation () 24 24

Table 3-10 Mechanical Properties of SUM 43 Black Surface Material

74

Stress-Strain Diagrams

0 2 4 6 8 10 12 14

-200

0

200

400

600

800

1000

1200

1400

1600

1800

應力 (MPa)

應變()

(a)

0 2 4 6 8 10

-200

0

200

400

600

800

1000

1200

1400

1600

應力

(MPa)

位移 ()

(b)

Fig 3-27 Stress-Strain Diagrams for (a) 3 Round Bar and (b) 5 Round Bar

(Note These curves were formulated using Visual Solutions Inc VisSim Software)

75

Cut-Off Area

(a)

(b)

Fig 3-28 Cut-Off Area of (a) 3 Round Bar and (b) 5 Round Bar

76

The force value (N) was retrieved from the Universal Testing Machine

The Poissonrsquos Ratio (ε) is calculated as

ε =

the values for the Poissonrsquos Ratio are in average around 0297

The Youngrsquos Modulus (E) is calculated as

E =

Where

Stress =

Cross-sectional Area =

where D is the Diameter

The value for D was in average around 1258 mm

The values shown by the computer because there is Slippage phenomena between the Clamp and the

specimen will not be taken into consideration for the elongation strain and Youngrsquos modulus and we will

refer to the values that we have meticulously calculated

77

Chapter 4 AR COATING IN DEPTH

41 Experimentrsquos Purpose and Principles

By means of a vacuum chamber and several other instruments we intend to apply Anti-Reflective

Coating using deposition process to a laser diode and in this way reduce its refraction so as to make it

lose less light in the process of amplification and we can control certain wavelengths we want produced

for certain desired applications in our case we are attempting to re-create a Bose-Einstein Condensate

An optimal BEC apparatus is shown in figure 4-1

Fig 4-1 BEC Apparatus

The main point of this experiment is to build a vacuum chamber system attach all the instrumentation

needed (Vacuum pump deposition meter and voltmeter) and use it to apply AR coating to a laser diode

After we have accomplished the AR coating other team will be in charge of designing the BEC apparatus

and use the results of our research

78

42 Experimentrsquos Equipment

421 Vacuum Chamber

For this research we designed a vacuum chamber whose main body is shown in figure 4-2 Its

dimensions are

Width 240 mm

Length 240 mm

Height 200 mm

Outer Diameter 4 in

Inner Diameter 15 in

Fig 4-2 Vacuum Chamber Main Body

The chamber is made up of 6 pass ways pass way A is the connection with the Laser Deposition

Equipment pass way B is the connection with the Turbo Pump and pass way C is for the connection with

the Deposition Source

A

C

B

79

Pass way C is for the deposition source as mentioned above This is a system where a thermal

resistance is heated by passing a high current through it which heats up a filament boat (made of tungsten)

where the material to be evaporated is place We control the temperature as such that the material will

evaporate and the heat will not cause the filament boat to crack

Because P = Isup2 R (where P is power I is current and R is resistance) to avoid the current to flow

where it is not desired we decided that the material for the Thermocouple shown in figure 4-3 should be

Copper ᴓ 63 mm We choose it that way because Copper has very good heat dissipation characteristics

and the resistance value is low It can reduce the value of the current enough to make the thermocouple to

create heat

Fig 4-3 Thermocouple

To the thermocouple we attach the tungsten filament boat We need to take notice of materials to be

used in this design because when using high current the tungsten filament boar will heat up and so the

material must be able to keep up with the heating potential of tungsten and has a low coefficient of heat

dissipation to avoid the tungsten to fail when heating up and therefore not evaporating Considering all

this we decide to use Stainless Steel

Because this clamp will be assembled inside the chamber after many revisions it was determined it

will have the shape shown in figure 4-4

Fig 4-4 Filament Boat Clamp Design

80

For the tungsten filament boat we bought the product from a distributor The dimensions are

Length 100 mm

Width 10 mm

Height 1 mm

Our thermocouple is 15 in but the pass way C is 4 in so we need to attach a Flange that connects

15in to 4in Because these specifications are quite difficult to achieve by Milling we had to use

electrical wire cutting

For the laser clamping system where the laser that is going to be AR coated will be placed will be

connected to pass way A the assembly is shown in figure 4-5 below

Fig 4-5 Cover Assembly

For this design we used an O-ring instead of a gasket so as to save time The design of the assembly

where the laser will be placed is shown in figure 4-6

Fig 4-6 Upper Cover Inner Assembly

D

E

F

81

Point D is the plate in the assembly where the laser diode will be fixed Because of the easy

processing we decide to use Aluminum and it is screwed to the top cover Point E is the connection for

the Quartz crystal resonator and it is designed in the same as point F in this way the results of the quartz

microbalance system will be more accurate in real time Point F is the final resting place for the laser

diode We use a Thor Labs Base with dimensions of ᴓ 9mm and ᴓ 56mm for two different size laser

diodes It just needs to be plugged in for easy installation

From figure 4-6 we know that the system needs signal system connections and because of the

change in temperature inside the chamber this could affect the functioning of the quartz microbalance so

we also need to install water tubes for cooling This is shown in figure 4-7 below

Fig 4-7 Diagram of Upper Cover Connections

In figure 4-8 we show the Feed through connections and their functions

Fig 4-8 Feed through Diagram

82

1 SQM-160 wire 5 Laser Connection 1 (Vin)

2 SQM-160 (G) 6 Laser Connection 2 (G)

3 K-Type-1 7 Laser Connection 3 (PD)

4 K-Type-2 8 Not In Use

The fully assembled chamber is shown in figure 4-9

Fig 4-9 Fully Assembled Chamber

422 Quartz Crystal Microbalance

For measuring the deposition on our target for coating we used the Inficon SQM-160 RateThickness

Monitor It is an easy to use instrument for measuring many types of thin-film coatings as shown in

figure 4-10

(a) Front Panel (b) Back Panel

Fig 4-10 Inficon SQM-160

83

Table 4-1 shows the technical specifications for this equipment

Number of sensors 2 Standard 4 additional optional

Sensor Frequency Range 40 MHz ~ 60 MHz

Reference Frequency Accuracy 002

Thickness Display Resolution 1 Aring

Thickness Resolution 015 Aring (Std) 0037 Aring (Hi Res)

Density of Stored Films 05-9999 gmcc

Tooling 10-399

Z-Factor 010-1000

Final Thickness 0000-9999k Aring

Measurement Period 15 to 2 sec

Simulation Mode Yes

Frequency Mode Yes

Rate Resolution 011 Arings

Dual Crystal Yes

Etch Mode Yes

Crystal Tooling 10-399

Crystal Fail Min Max 40 to 60 MHz 41 to 61 MHz

Power 100-120 200-240~plusmn10 nominal 20W

Operation Environment 0degC ~ 50degC

0 ~ 80 RH non-condensing

0 ~ 2000 meters

Class 1 Equipment

Pollution Degree 2

Rack Dimensions 885mm x 2127mm x 1969mm

Weight 27 kg

Table 4-1 Inficon SQM-160 RateThickness Monitor Specs

84

To the SQM-160 we need to connect an Oscillator We use the Sigma Instruments Remote Oscillator

Ser No 2 268 as shown in figure 4-11

Fig 4-11 Sigma Instruments Remote Oscillator

The connections diagram is shown in figure 4-12

Fig 4-12 SQM-160 Connections Diagram

85

423 Turbo Pump

For our experiments we used the Pfeiffer TCP 015 Electronic Drive Unit shown below in figure 4-13

Table 4-2 shows the technical specifications for this equipment

(a) Front Panel (b) Back Panel

Fig 4-13 Pfeiffer TCP 015 Electronic Drive

Connection Voltage (100V) 90-112

Mains Frequency 5060 Hz

Start-up Current 22 A

Nominal Frequency 1500 Hz

Rotation Speed 10V = 1500Hz plusmn2

Analog Output Current 10 V = 25 A plusmn 5

Rotation Speed Switchpoint 750 Hz

Works Setting 8 min

Permissible Ambient Temperature 0degC ~ 40degC

Dimensions Front Panel 1285mm x 1063mm

Insertion Length 227mm

Weight 27 Kg

Table 4-2 Pfeiffer TCP 015 Electronic Drive Specs

86

The connections diagram is shown in figure 4-14

Fig 4-14Connections Diagram for Pfeiffer TCP 015

To measure the pressure inside the chamber we use the Granville Phillips 375 Convectron Vacuum

Pressure Controller shown in figure 4-15

(a) Front Panel (b) Back Panel

Fig 4-15 Granville Phillips 375 Convectron

87

Its dimensions are shown in figure 4-16

Fig 4-16 Dimensions of Convectron

Table 4-3 shows the technical specifications for this equipment

Table 4-3 Granville Phillips 375 Convectron Vacuum Pressure Controller Specs

88

424 Multimeter

For our experiment we used the Keithley 2000 Digital Multimeter as shown in figure 4-17

(a) Front Panel (b) Back Panel

Fig 4-17 Keithley Model 2000 6-12-Digit Digital Multimeter

Its technical specifications are shown in table 4-4

Table 4-4 Keithley Model 2000 6-12-Digit Digital Multimeter Specs

89

43 Experiment Procedure

1 Connecting together the equipment and the chamber

(1) We first connect the resonator to the thickness monitor and connect the other side to the

chamber

(2) We now connect the flexible tubes to the turbo pump on one side and to the chamber on the

other

(3) We need to check that tubes are tightly connected to avoid any leaks in the vacuum pumping

process which will not allow us to get to our goal of Torr As shown in figure 4-18

(4) Connect the convectron to the system as shown in figure 4-19

Fig 4-18 checking for leaks using alcohol

Fig 4-19 Convectron attached to System

90

(5) Attach the clamps of the Multimeter to the bottom of the chamber as shown in figure 4-20

(6) Place the Quartz crystal in place

(7) Close tight vacuum chamber

(8) Connect all electrical appliances to power source

Fig 4-20 Multimeter Connections

2 Starting up the System

(1) We turn on all the devices as such Check all systems are ready to function Reset all values

that might be left over from previous tests

(2) Start the thickness monitor and set all values for this experiment In our case we got to testing

the system but not actual coating So we used the simulation mode of the thickness monitor as

shown in figure 4-21

Fig 4-21 Simulation Mode

91

(3) Start the turbo pump Make sure the lid on the vacuum chamber is tightly closed

(4) Start convectron and record initial pressure

(5) Start Multimeter and record initial current

3 Coating Process

(1) If we have the deposition material inside the filament boat the power source for the high

current must be started as well

(2) Record all initial values for thickness current pressure

(3) For an ideal experiment we need a thickness of around 101 nm a pressure of Torr and

a current of 300 A

44 Results

From previous experiments we have shown that we can turn a LED into a laser by means of AR

Coating In figure 4-22 shown below we can compare the actual results of a Diode before and after AR

coating From the blue line we can see that when the diode is at a current of 15mA its light will change

from LED to laser and if we look at the red line its critical current is around 30 to 35 mA

Fig 4-22 AR Coating Comparison for Laser Diodes

This means that the light emitted is not as strong as if the diode had been coated because inside the

chamber there must be some excitation first so the reflectivity of both sides inside the diode must be high

So because of the coating in one of the sides we have opened a door and let the light come out so the

critical current is risen as such and will be higher value than that of before the coating

92

In the following figures we can see the difference between before and after coating in a material The

thickness is around 1016 nm for this material

Fig 4-23 Before Coating

Fig 4-24 After Coating

93

Chapter 5 CONCLUSIONS AND RECOMMENDATIONS

51 Conclusions

For the first part of this independent study taking into consideration the data that came out of our

research and that sent by the provider we can say

1 SUM 23 after heat treatment will unexpectedly develop cracking in the middle of the tensile

testing process and suddenly break

2 Itrsquos possible that in the process of heat treatment to the SUM 23 material the treatment was not

uniform and this will create a pre-loaded moment force on one side that pushes on the other side

of the specimen resulting in material deformation

3 In the process of attaching the strain gauges to the materials it is very easy to make errors due to

poor adhesion or sudden removal in the tensile testing process

For our second part of the independent study the following can be made

1 At the beginning of this independent study we had no idea what Bose-Einstein Condensate was

or what was its purpose After much literature we finally comprehended the basic principles to

put into practice for our research

2 Our systemrsquos basic working principles and equipmentrsquos complexity are a little difficult to grasp

but hopefully we were able to understand enough of it

3 Theoretically from relation between the power and current we can know the advantages and

disadvantages of AR Coating

4 We were able to assemble the system and run test on its functions Even though we were able to

do this there is still much more work left to do with this system

52 Recommendations

For the Tensile Testing the following can be said

1 Ask the provider to check on the process of heat treatment on the SUM 23 material and give

them the information we have gathered through our test so they can correct for the mechanical

properties found if any change is needed

2 To avoid the problem of the inaccuracy of the poor adhesion of strain gauges we can attach

multiple strain gauges to the same one specimen so as to correlate data and improve our results

For the AR Coating the following can be said

1 We need to make sure that there are no physical defects on the main body of the chamber so as to

achieve maximum efficiency in the vacuum process If there was then the vacuum will arrive to

certain point and then start to decrease

2 It would be preferable to add some sort of visual aid that will allow the user to check the inside of

the chamber without actually opening it This will help us determine at what times we should

manipulate the current to better evaporate the substrate

94

REFERENCES

[1] A L Window Strain Gauge Technology Elsevier Applied Science London and New York 2nd

Edition 1992

[2] CC Perry and HR Lissner Strain Gauge Primer McGraw-Hill Book Co Inc New York 1955

[3] James W Dally William F Riley McGraw-Hill 1978

[4] University of Colorado Boulder BEC - What is it and where did the idea come from

httpwwwcoloradoeduphysics2000becwhat_is_ithtml

[5] Ultraslow Light amp Bose-Einstein Condensates Two-way Control with Coherent Light amp Atom

Fields Harvard Hau Lab Dr Lene Vestergaard Hau Optics amp Photonics News 16 1995

[6] The Art of Taming Light Ultra-slow and Stopped Light Harvard Hau Lab Dr Lene

Vestergaard Hau Europhysics News 2004

[7] Nonlinear Optics Shocking Superfluids Harvard Hau Lab Dr Lene Vestergaard Hau Nature

Physics 2007

[8] Model P3 Strain Indicator and Recorder Instruction Manual Vishay Micro-Measurements 2005

[9] Granville-Phillips Series 375 Convectron Vacuum Gauge Controller Instruction Manual Brooks

Automation 2008

[10] Effect of Film Thickness on the Validity of the Sauerbrey Equation for Hydrated Polyelectrolyte

Films Vogt Lin Wu White 2004

[11] Quartz Crystal Microbalance Study of DNA Immobilization and Hybridization for DNA Sensor

Development Chang Zhao 2008

[12] Installation of Strain Gages with SR-4 PrecoatAdhesive Vishay Micro-Measurements 2005

[13] Strain Gauge Measurement ndash A Tutorial National Instruments 1998

[14] Correlation between Vickers Hardness Number and Yield Stress of Cold-Formed Products

Yavuz Tekkaya

[15] httpsenwikipediaorg

Page 72: PC Hinge Materials Testing and AR Laser Diode Coating

72

Cut-Off Area

(a)

(b)

Fig 3-25 Cut-Off Area of (a) 4 Round Bar and (b) 5 Round Bar

73

SUM 43 Black Surface Material

Fig 3-26 SUM 43 Black Surface Material

Number 3 5

Hardness(HRB) 56 56

Yield Stress (MPa) 1416 1361

Tensile Strength (MPa) 1591 1402

Poissonrsquos Ratio 029 031

Youngrsquos Modulus (GPa) 200 202

Cut-off Area Shrinking () 139 124

Elongation () 24 24

Table 3-10 Mechanical Properties of SUM 43 Black Surface Material

74

Stress-Strain Diagrams

0 2 4 6 8 10 12 14

-200

0

200

400

600

800

1000

1200

1400

1600

1800

應力 (MPa)

應變()

(a)

0 2 4 6 8 10

-200

0

200

400

600

800

1000

1200

1400

1600

應力

(MPa)

位移 ()

(b)

Fig 3-27 Stress-Strain Diagrams for (a) 3 Round Bar and (b) 5 Round Bar

(Note These curves were formulated using Visual Solutions Inc VisSim Software)

75

Cut-Off Area

(a)

(b)

Fig 3-28 Cut-Off Area of (a) 3 Round Bar and (b) 5 Round Bar

76

The force value (N) was retrieved from the Universal Testing Machine

The Poissonrsquos Ratio (ε) is calculated as

ε =

the values for the Poissonrsquos Ratio are in average around 0297

The Youngrsquos Modulus (E) is calculated as

E =

Where

Stress =

Cross-sectional Area =

where D is the Diameter

The value for D was in average around 1258 mm

The values shown by the computer because there is Slippage phenomena between the Clamp and the

specimen will not be taken into consideration for the elongation strain and Youngrsquos modulus and we will

refer to the values that we have meticulously calculated

77

Chapter 4 AR COATING IN DEPTH

41 Experimentrsquos Purpose and Principles

By means of a vacuum chamber and several other instruments we intend to apply Anti-Reflective

Coating using deposition process to a laser diode and in this way reduce its refraction so as to make it

lose less light in the process of amplification and we can control certain wavelengths we want produced

for certain desired applications in our case we are attempting to re-create a Bose-Einstein Condensate

An optimal BEC apparatus is shown in figure 4-1

Fig 4-1 BEC Apparatus

The main point of this experiment is to build a vacuum chamber system attach all the instrumentation

needed (Vacuum pump deposition meter and voltmeter) and use it to apply AR coating to a laser diode

After we have accomplished the AR coating other team will be in charge of designing the BEC apparatus

and use the results of our research

78

42 Experimentrsquos Equipment

421 Vacuum Chamber

For this research we designed a vacuum chamber whose main body is shown in figure 4-2 Its

dimensions are

Width 240 mm

Length 240 mm

Height 200 mm

Outer Diameter 4 in

Inner Diameter 15 in

Fig 4-2 Vacuum Chamber Main Body

The chamber is made up of 6 pass ways pass way A is the connection with the Laser Deposition

Equipment pass way B is the connection with the Turbo Pump and pass way C is for the connection with

the Deposition Source

A

C

B

79

Pass way C is for the deposition source as mentioned above This is a system where a thermal

resistance is heated by passing a high current through it which heats up a filament boat (made of tungsten)

where the material to be evaporated is place We control the temperature as such that the material will

evaporate and the heat will not cause the filament boat to crack

Because P = Isup2 R (where P is power I is current and R is resistance) to avoid the current to flow

where it is not desired we decided that the material for the Thermocouple shown in figure 4-3 should be

Copper ᴓ 63 mm We choose it that way because Copper has very good heat dissipation characteristics

and the resistance value is low It can reduce the value of the current enough to make the thermocouple to

create heat

Fig 4-3 Thermocouple

To the thermocouple we attach the tungsten filament boat We need to take notice of materials to be

used in this design because when using high current the tungsten filament boar will heat up and so the

material must be able to keep up with the heating potential of tungsten and has a low coefficient of heat

dissipation to avoid the tungsten to fail when heating up and therefore not evaporating Considering all

this we decide to use Stainless Steel

Because this clamp will be assembled inside the chamber after many revisions it was determined it

will have the shape shown in figure 4-4

Fig 4-4 Filament Boat Clamp Design

80

For the tungsten filament boat we bought the product from a distributor The dimensions are

Length 100 mm

Width 10 mm

Height 1 mm

Our thermocouple is 15 in but the pass way C is 4 in so we need to attach a Flange that connects

15in to 4in Because these specifications are quite difficult to achieve by Milling we had to use

electrical wire cutting

For the laser clamping system where the laser that is going to be AR coated will be placed will be

connected to pass way A the assembly is shown in figure 4-5 below

Fig 4-5 Cover Assembly

For this design we used an O-ring instead of a gasket so as to save time The design of the assembly

where the laser will be placed is shown in figure 4-6

Fig 4-6 Upper Cover Inner Assembly

D

E

F

81

Point D is the plate in the assembly where the laser diode will be fixed Because of the easy

processing we decide to use Aluminum and it is screwed to the top cover Point E is the connection for

the Quartz crystal resonator and it is designed in the same as point F in this way the results of the quartz

microbalance system will be more accurate in real time Point F is the final resting place for the laser

diode We use a Thor Labs Base with dimensions of ᴓ 9mm and ᴓ 56mm for two different size laser

diodes It just needs to be plugged in for easy installation

From figure 4-6 we know that the system needs signal system connections and because of the

change in temperature inside the chamber this could affect the functioning of the quartz microbalance so

we also need to install water tubes for cooling This is shown in figure 4-7 below

Fig 4-7 Diagram of Upper Cover Connections

In figure 4-8 we show the Feed through connections and their functions

Fig 4-8 Feed through Diagram

82

1 SQM-160 wire 5 Laser Connection 1 (Vin)

2 SQM-160 (G) 6 Laser Connection 2 (G)

3 K-Type-1 7 Laser Connection 3 (PD)

4 K-Type-2 8 Not In Use

The fully assembled chamber is shown in figure 4-9

Fig 4-9 Fully Assembled Chamber

422 Quartz Crystal Microbalance

For measuring the deposition on our target for coating we used the Inficon SQM-160 RateThickness

Monitor It is an easy to use instrument for measuring many types of thin-film coatings as shown in

figure 4-10

(a) Front Panel (b) Back Panel

Fig 4-10 Inficon SQM-160

83

Table 4-1 shows the technical specifications for this equipment

Number of sensors 2 Standard 4 additional optional

Sensor Frequency Range 40 MHz ~ 60 MHz

Reference Frequency Accuracy 002

Thickness Display Resolution 1 Aring

Thickness Resolution 015 Aring (Std) 0037 Aring (Hi Res)

Density of Stored Films 05-9999 gmcc

Tooling 10-399

Z-Factor 010-1000

Final Thickness 0000-9999k Aring

Measurement Period 15 to 2 sec

Simulation Mode Yes

Frequency Mode Yes

Rate Resolution 011 Arings

Dual Crystal Yes

Etch Mode Yes

Crystal Tooling 10-399

Crystal Fail Min Max 40 to 60 MHz 41 to 61 MHz

Power 100-120 200-240~plusmn10 nominal 20W

Operation Environment 0degC ~ 50degC

0 ~ 80 RH non-condensing

0 ~ 2000 meters

Class 1 Equipment

Pollution Degree 2

Rack Dimensions 885mm x 2127mm x 1969mm

Weight 27 kg

Table 4-1 Inficon SQM-160 RateThickness Monitor Specs

84

To the SQM-160 we need to connect an Oscillator We use the Sigma Instruments Remote Oscillator

Ser No 2 268 as shown in figure 4-11

Fig 4-11 Sigma Instruments Remote Oscillator

The connections diagram is shown in figure 4-12

Fig 4-12 SQM-160 Connections Diagram

85

423 Turbo Pump

For our experiments we used the Pfeiffer TCP 015 Electronic Drive Unit shown below in figure 4-13

Table 4-2 shows the technical specifications for this equipment

(a) Front Panel (b) Back Panel

Fig 4-13 Pfeiffer TCP 015 Electronic Drive

Connection Voltage (100V) 90-112

Mains Frequency 5060 Hz

Start-up Current 22 A

Nominal Frequency 1500 Hz

Rotation Speed 10V = 1500Hz plusmn2

Analog Output Current 10 V = 25 A plusmn 5

Rotation Speed Switchpoint 750 Hz

Works Setting 8 min

Permissible Ambient Temperature 0degC ~ 40degC

Dimensions Front Panel 1285mm x 1063mm

Insertion Length 227mm

Weight 27 Kg

Table 4-2 Pfeiffer TCP 015 Electronic Drive Specs

86

The connections diagram is shown in figure 4-14

Fig 4-14Connections Diagram for Pfeiffer TCP 015

To measure the pressure inside the chamber we use the Granville Phillips 375 Convectron Vacuum

Pressure Controller shown in figure 4-15

(a) Front Panel (b) Back Panel

Fig 4-15 Granville Phillips 375 Convectron

87

Its dimensions are shown in figure 4-16

Fig 4-16 Dimensions of Convectron

Table 4-3 shows the technical specifications for this equipment

Table 4-3 Granville Phillips 375 Convectron Vacuum Pressure Controller Specs

88

424 Multimeter

For our experiment we used the Keithley 2000 Digital Multimeter as shown in figure 4-17

(a) Front Panel (b) Back Panel

Fig 4-17 Keithley Model 2000 6-12-Digit Digital Multimeter

Its technical specifications are shown in table 4-4

Table 4-4 Keithley Model 2000 6-12-Digit Digital Multimeter Specs

89

43 Experiment Procedure

1 Connecting together the equipment and the chamber

(1) We first connect the resonator to the thickness monitor and connect the other side to the

chamber

(2) We now connect the flexible tubes to the turbo pump on one side and to the chamber on the

other

(3) We need to check that tubes are tightly connected to avoid any leaks in the vacuum pumping

process which will not allow us to get to our goal of Torr As shown in figure 4-18

(4) Connect the convectron to the system as shown in figure 4-19

Fig 4-18 checking for leaks using alcohol

Fig 4-19 Convectron attached to System

90

(5) Attach the clamps of the Multimeter to the bottom of the chamber as shown in figure 4-20

(6) Place the Quartz crystal in place

(7) Close tight vacuum chamber

(8) Connect all electrical appliances to power source

Fig 4-20 Multimeter Connections

2 Starting up the System

(1) We turn on all the devices as such Check all systems are ready to function Reset all values

that might be left over from previous tests

(2) Start the thickness monitor and set all values for this experiment In our case we got to testing

the system but not actual coating So we used the simulation mode of the thickness monitor as

shown in figure 4-21

Fig 4-21 Simulation Mode

91

(3) Start the turbo pump Make sure the lid on the vacuum chamber is tightly closed

(4) Start convectron and record initial pressure

(5) Start Multimeter and record initial current

3 Coating Process

(1) If we have the deposition material inside the filament boat the power source for the high

current must be started as well

(2) Record all initial values for thickness current pressure

(3) For an ideal experiment we need a thickness of around 101 nm a pressure of Torr and

a current of 300 A

44 Results

From previous experiments we have shown that we can turn a LED into a laser by means of AR

Coating In figure 4-22 shown below we can compare the actual results of a Diode before and after AR

coating From the blue line we can see that when the diode is at a current of 15mA its light will change

from LED to laser and if we look at the red line its critical current is around 30 to 35 mA

Fig 4-22 AR Coating Comparison for Laser Diodes

This means that the light emitted is not as strong as if the diode had been coated because inside the

chamber there must be some excitation first so the reflectivity of both sides inside the diode must be high

So because of the coating in one of the sides we have opened a door and let the light come out so the

critical current is risen as such and will be higher value than that of before the coating

92

In the following figures we can see the difference between before and after coating in a material The

thickness is around 1016 nm for this material

Fig 4-23 Before Coating

Fig 4-24 After Coating

93

Chapter 5 CONCLUSIONS AND RECOMMENDATIONS

51 Conclusions

For the first part of this independent study taking into consideration the data that came out of our

research and that sent by the provider we can say

1 SUM 23 after heat treatment will unexpectedly develop cracking in the middle of the tensile

testing process and suddenly break

2 Itrsquos possible that in the process of heat treatment to the SUM 23 material the treatment was not

uniform and this will create a pre-loaded moment force on one side that pushes on the other side

of the specimen resulting in material deformation

3 In the process of attaching the strain gauges to the materials it is very easy to make errors due to

poor adhesion or sudden removal in the tensile testing process

For our second part of the independent study the following can be made

1 At the beginning of this independent study we had no idea what Bose-Einstein Condensate was

or what was its purpose After much literature we finally comprehended the basic principles to

put into practice for our research

2 Our systemrsquos basic working principles and equipmentrsquos complexity are a little difficult to grasp

but hopefully we were able to understand enough of it

3 Theoretically from relation between the power and current we can know the advantages and

disadvantages of AR Coating

4 We were able to assemble the system and run test on its functions Even though we were able to

do this there is still much more work left to do with this system

52 Recommendations

For the Tensile Testing the following can be said

1 Ask the provider to check on the process of heat treatment on the SUM 23 material and give

them the information we have gathered through our test so they can correct for the mechanical

properties found if any change is needed

2 To avoid the problem of the inaccuracy of the poor adhesion of strain gauges we can attach

multiple strain gauges to the same one specimen so as to correlate data and improve our results

For the AR Coating the following can be said

1 We need to make sure that there are no physical defects on the main body of the chamber so as to

achieve maximum efficiency in the vacuum process If there was then the vacuum will arrive to

certain point and then start to decrease

2 It would be preferable to add some sort of visual aid that will allow the user to check the inside of

the chamber without actually opening it This will help us determine at what times we should

manipulate the current to better evaporate the substrate

94

REFERENCES

[1] A L Window Strain Gauge Technology Elsevier Applied Science London and New York 2nd

Edition 1992

[2] CC Perry and HR Lissner Strain Gauge Primer McGraw-Hill Book Co Inc New York 1955

[3] James W Dally William F Riley McGraw-Hill 1978

[4] University of Colorado Boulder BEC - What is it and where did the idea come from

httpwwwcoloradoeduphysics2000becwhat_is_ithtml

[5] Ultraslow Light amp Bose-Einstein Condensates Two-way Control with Coherent Light amp Atom

Fields Harvard Hau Lab Dr Lene Vestergaard Hau Optics amp Photonics News 16 1995

[6] The Art of Taming Light Ultra-slow and Stopped Light Harvard Hau Lab Dr Lene

Vestergaard Hau Europhysics News 2004

[7] Nonlinear Optics Shocking Superfluids Harvard Hau Lab Dr Lene Vestergaard Hau Nature

Physics 2007

[8] Model P3 Strain Indicator and Recorder Instruction Manual Vishay Micro-Measurements 2005

[9] Granville-Phillips Series 375 Convectron Vacuum Gauge Controller Instruction Manual Brooks

Automation 2008

[10] Effect of Film Thickness on the Validity of the Sauerbrey Equation for Hydrated Polyelectrolyte

Films Vogt Lin Wu White 2004

[11] Quartz Crystal Microbalance Study of DNA Immobilization and Hybridization for DNA Sensor

Development Chang Zhao 2008

[12] Installation of Strain Gages with SR-4 PrecoatAdhesive Vishay Micro-Measurements 2005

[13] Strain Gauge Measurement ndash A Tutorial National Instruments 1998

[14] Correlation between Vickers Hardness Number and Yield Stress of Cold-Formed Products

Yavuz Tekkaya

[15] httpsenwikipediaorg

Page 73: PC Hinge Materials Testing and AR Laser Diode Coating

73

SUM 43 Black Surface Material

Fig 3-26 SUM 43 Black Surface Material

Number 3 5

Hardness(HRB) 56 56

Yield Stress (MPa) 1416 1361

Tensile Strength (MPa) 1591 1402

Poissonrsquos Ratio 029 031

Youngrsquos Modulus (GPa) 200 202

Cut-off Area Shrinking () 139 124

Elongation () 24 24

Table 3-10 Mechanical Properties of SUM 43 Black Surface Material

74

Stress-Strain Diagrams

0 2 4 6 8 10 12 14

-200

0

200

400

600

800

1000

1200

1400

1600

1800

應力 (MPa)

應變()

(a)

0 2 4 6 8 10

-200

0

200

400

600

800

1000

1200

1400

1600

應力

(MPa)

位移 ()

(b)

Fig 3-27 Stress-Strain Diagrams for (a) 3 Round Bar and (b) 5 Round Bar

(Note These curves were formulated using Visual Solutions Inc VisSim Software)

75

Cut-Off Area

(a)

(b)

Fig 3-28 Cut-Off Area of (a) 3 Round Bar and (b) 5 Round Bar

76

The force value (N) was retrieved from the Universal Testing Machine

The Poissonrsquos Ratio (ε) is calculated as

ε =

the values for the Poissonrsquos Ratio are in average around 0297

The Youngrsquos Modulus (E) is calculated as

E =

Where

Stress =

Cross-sectional Area =

where D is the Diameter

The value for D was in average around 1258 mm

The values shown by the computer because there is Slippage phenomena between the Clamp and the

specimen will not be taken into consideration for the elongation strain and Youngrsquos modulus and we will

refer to the values that we have meticulously calculated

77

Chapter 4 AR COATING IN DEPTH

41 Experimentrsquos Purpose and Principles

By means of a vacuum chamber and several other instruments we intend to apply Anti-Reflective

Coating using deposition process to a laser diode and in this way reduce its refraction so as to make it

lose less light in the process of amplification and we can control certain wavelengths we want produced

for certain desired applications in our case we are attempting to re-create a Bose-Einstein Condensate

An optimal BEC apparatus is shown in figure 4-1

Fig 4-1 BEC Apparatus

The main point of this experiment is to build a vacuum chamber system attach all the instrumentation

needed (Vacuum pump deposition meter and voltmeter) and use it to apply AR coating to a laser diode

After we have accomplished the AR coating other team will be in charge of designing the BEC apparatus

and use the results of our research

78

42 Experimentrsquos Equipment

421 Vacuum Chamber

For this research we designed a vacuum chamber whose main body is shown in figure 4-2 Its

dimensions are

Width 240 mm

Length 240 mm

Height 200 mm

Outer Diameter 4 in

Inner Diameter 15 in

Fig 4-2 Vacuum Chamber Main Body

The chamber is made up of 6 pass ways pass way A is the connection with the Laser Deposition

Equipment pass way B is the connection with the Turbo Pump and pass way C is for the connection with

the Deposition Source

A

C

B

79

Pass way C is for the deposition source as mentioned above This is a system where a thermal

resistance is heated by passing a high current through it which heats up a filament boat (made of tungsten)

where the material to be evaporated is place We control the temperature as such that the material will

evaporate and the heat will not cause the filament boat to crack

Because P = Isup2 R (where P is power I is current and R is resistance) to avoid the current to flow

where it is not desired we decided that the material for the Thermocouple shown in figure 4-3 should be

Copper ᴓ 63 mm We choose it that way because Copper has very good heat dissipation characteristics

and the resistance value is low It can reduce the value of the current enough to make the thermocouple to

create heat

Fig 4-3 Thermocouple

To the thermocouple we attach the tungsten filament boat We need to take notice of materials to be

used in this design because when using high current the tungsten filament boar will heat up and so the

material must be able to keep up with the heating potential of tungsten and has a low coefficient of heat

dissipation to avoid the tungsten to fail when heating up and therefore not evaporating Considering all

this we decide to use Stainless Steel

Because this clamp will be assembled inside the chamber after many revisions it was determined it

will have the shape shown in figure 4-4

Fig 4-4 Filament Boat Clamp Design

80

For the tungsten filament boat we bought the product from a distributor The dimensions are

Length 100 mm

Width 10 mm

Height 1 mm

Our thermocouple is 15 in but the pass way C is 4 in so we need to attach a Flange that connects

15in to 4in Because these specifications are quite difficult to achieve by Milling we had to use

electrical wire cutting

For the laser clamping system where the laser that is going to be AR coated will be placed will be

connected to pass way A the assembly is shown in figure 4-5 below

Fig 4-5 Cover Assembly

For this design we used an O-ring instead of a gasket so as to save time The design of the assembly

where the laser will be placed is shown in figure 4-6

Fig 4-6 Upper Cover Inner Assembly

D

E

F

81

Point D is the plate in the assembly where the laser diode will be fixed Because of the easy

processing we decide to use Aluminum and it is screwed to the top cover Point E is the connection for

the Quartz crystal resonator and it is designed in the same as point F in this way the results of the quartz

microbalance system will be more accurate in real time Point F is the final resting place for the laser

diode We use a Thor Labs Base with dimensions of ᴓ 9mm and ᴓ 56mm for two different size laser

diodes It just needs to be plugged in for easy installation

From figure 4-6 we know that the system needs signal system connections and because of the

change in temperature inside the chamber this could affect the functioning of the quartz microbalance so

we also need to install water tubes for cooling This is shown in figure 4-7 below

Fig 4-7 Diagram of Upper Cover Connections

In figure 4-8 we show the Feed through connections and their functions

Fig 4-8 Feed through Diagram

82

1 SQM-160 wire 5 Laser Connection 1 (Vin)

2 SQM-160 (G) 6 Laser Connection 2 (G)

3 K-Type-1 7 Laser Connection 3 (PD)

4 K-Type-2 8 Not In Use

The fully assembled chamber is shown in figure 4-9

Fig 4-9 Fully Assembled Chamber

422 Quartz Crystal Microbalance

For measuring the deposition on our target for coating we used the Inficon SQM-160 RateThickness

Monitor It is an easy to use instrument for measuring many types of thin-film coatings as shown in

figure 4-10

(a) Front Panel (b) Back Panel

Fig 4-10 Inficon SQM-160

83

Table 4-1 shows the technical specifications for this equipment

Number of sensors 2 Standard 4 additional optional

Sensor Frequency Range 40 MHz ~ 60 MHz

Reference Frequency Accuracy 002

Thickness Display Resolution 1 Aring

Thickness Resolution 015 Aring (Std) 0037 Aring (Hi Res)

Density of Stored Films 05-9999 gmcc

Tooling 10-399

Z-Factor 010-1000

Final Thickness 0000-9999k Aring

Measurement Period 15 to 2 sec

Simulation Mode Yes

Frequency Mode Yes

Rate Resolution 011 Arings

Dual Crystal Yes

Etch Mode Yes

Crystal Tooling 10-399

Crystal Fail Min Max 40 to 60 MHz 41 to 61 MHz

Power 100-120 200-240~plusmn10 nominal 20W

Operation Environment 0degC ~ 50degC

0 ~ 80 RH non-condensing

0 ~ 2000 meters

Class 1 Equipment

Pollution Degree 2

Rack Dimensions 885mm x 2127mm x 1969mm

Weight 27 kg

Table 4-1 Inficon SQM-160 RateThickness Monitor Specs

84

To the SQM-160 we need to connect an Oscillator We use the Sigma Instruments Remote Oscillator

Ser No 2 268 as shown in figure 4-11

Fig 4-11 Sigma Instruments Remote Oscillator

The connections diagram is shown in figure 4-12

Fig 4-12 SQM-160 Connections Diagram

85

423 Turbo Pump

For our experiments we used the Pfeiffer TCP 015 Electronic Drive Unit shown below in figure 4-13

Table 4-2 shows the technical specifications for this equipment

(a) Front Panel (b) Back Panel

Fig 4-13 Pfeiffer TCP 015 Electronic Drive

Connection Voltage (100V) 90-112

Mains Frequency 5060 Hz

Start-up Current 22 A

Nominal Frequency 1500 Hz

Rotation Speed 10V = 1500Hz plusmn2

Analog Output Current 10 V = 25 A plusmn 5

Rotation Speed Switchpoint 750 Hz

Works Setting 8 min

Permissible Ambient Temperature 0degC ~ 40degC

Dimensions Front Panel 1285mm x 1063mm

Insertion Length 227mm

Weight 27 Kg

Table 4-2 Pfeiffer TCP 015 Electronic Drive Specs

86

The connections diagram is shown in figure 4-14

Fig 4-14Connections Diagram for Pfeiffer TCP 015

To measure the pressure inside the chamber we use the Granville Phillips 375 Convectron Vacuum

Pressure Controller shown in figure 4-15

(a) Front Panel (b) Back Panel

Fig 4-15 Granville Phillips 375 Convectron

87

Its dimensions are shown in figure 4-16

Fig 4-16 Dimensions of Convectron

Table 4-3 shows the technical specifications for this equipment

Table 4-3 Granville Phillips 375 Convectron Vacuum Pressure Controller Specs

88

424 Multimeter

For our experiment we used the Keithley 2000 Digital Multimeter as shown in figure 4-17

(a) Front Panel (b) Back Panel

Fig 4-17 Keithley Model 2000 6-12-Digit Digital Multimeter

Its technical specifications are shown in table 4-4

Table 4-4 Keithley Model 2000 6-12-Digit Digital Multimeter Specs

89

43 Experiment Procedure

1 Connecting together the equipment and the chamber

(1) We first connect the resonator to the thickness monitor and connect the other side to the

chamber

(2) We now connect the flexible tubes to the turbo pump on one side and to the chamber on the

other

(3) We need to check that tubes are tightly connected to avoid any leaks in the vacuum pumping

process which will not allow us to get to our goal of Torr As shown in figure 4-18

(4) Connect the convectron to the system as shown in figure 4-19

Fig 4-18 checking for leaks using alcohol

Fig 4-19 Convectron attached to System

90

(5) Attach the clamps of the Multimeter to the bottom of the chamber as shown in figure 4-20

(6) Place the Quartz crystal in place

(7) Close tight vacuum chamber

(8) Connect all electrical appliances to power source

Fig 4-20 Multimeter Connections

2 Starting up the System

(1) We turn on all the devices as such Check all systems are ready to function Reset all values

that might be left over from previous tests

(2) Start the thickness monitor and set all values for this experiment In our case we got to testing

the system but not actual coating So we used the simulation mode of the thickness monitor as

shown in figure 4-21

Fig 4-21 Simulation Mode

91

(3) Start the turbo pump Make sure the lid on the vacuum chamber is tightly closed

(4) Start convectron and record initial pressure

(5) Start Multimeter and record initial current

3 Coating Process

(1) If we have the deposition material inside the filament boat the power source for the high

current must be started as well

(2) Record all initial values for thickness current pressure

(3) For an ideal experiment we need a thickness of around 101 nm a pressure of Torr and

a current of 300 A

44 Results

From previous experiments we have shown that we can turn a LED into a laser by means of AR

Coating In figure 4-22 shown below we can compare the actual results of a Diode before and after AR

coating From the blue line we can see that when the diode is at a current of 15mA its light will change

from LED to laser and if we look at the red line its critical current is around 30 to 35 mA

Fig 4-22 AR Coating Comparison for Laser Diodes

This means that the light emitted is not as strong as if the diode had been coated because inside the

chamber there must be some excitation first so the reflectivity of both sides inside the diode must be high

So because of the coating in one of the sides we have opened a door and let the light come out so the

critical current is risen as such and will be higher value than that of before the coating

92

In the following figures we can see the difference between before and after coating in a material The

thickness is around 1016 nm for this material

Fig 4-23 Before Coating

Fig 4-24 After Coating

93

Chapter 5 CONCLUSIONS AND RECOMMENDATIONS

51 Conclusions

For the first part of this independent study taking into consideration the data that came out of our

research and that sent by the provider we can say

1 SUM 23 after heat treatment will unexpectedly develop cracking in the middle of the tensile

testing process and suddenly break

2 Itrsquos possible that in the process of heat treatment to the SUM 23 material the treatment was not

uniform and this will create a pre-loaded moment force on one side that pushes on the other side

of the specimen resulting in material deformation

3 In the process of attaching the strain gauges to the materials it is very easy to make errors due to

poor adhesion or sudden removal in the tensile testing process

For our second part of the independent study the following can be made

1 At the beginning of this independent study we had no idea what Bose-Einstein Condensate was

or what was its purpose After much literature we finally comprehended the basic principles to

put into practice for our research

2 Our systemrsquos basic working principles and equipmentrsquos complexity are a little difficult to grasp

but hopefully we were able to understand enough of it

3 Theoretically from relation between the power and current we can know the advantages and

disadvantages of AR Coating

4 We were able to assemble the system and run test on its functions Even though we were able to

do this there is still much more work left to do with this system

52 Recommendations

For the Tensile Testing the following can be said

1 Ask the provider to check on the process of heat treatment on the SUM 23 material and give

them the information we have gathered through our test so they can correct for the mechanical

properties found if any change is needed

2 To avoid the problem of the inaccuracy of the poor adhesion of strain gauges we can attach

multiple strain gauges to the same one specimen so as to correlate data and improve our results

For the AR Coating the following can be said

1 We need to make sure that there are no physical defects on the main body of the chamber so as to

achieve maximum efficiency in the vacuum process If there was then the vacuum will arrive to

certain point and then start to decrease

2 It would be preferable to add some sort of visual aid that will allow the user to check the inside of

the chamber without actually opening it This will help us determine at what times we should

manipulate the current to better evaporate the substrate

94

REFERENCES

[1] A L Window Strain Gauge Technology Elsevier Applied Science London and New York 2nd

Edition 1992

[2] CC Perry and HR Lissner Strain Gauge Primer McGraw-Hill Book Co Inc New York 1955

[3] James W Dally William F Riley McGraw-Hill 1978

[4] University of Colorado Boulder BEC - What is it and where did the idea come from

httpwwwcoloradoeduphysics2000becwhat_is_ithtml

[5] Ultraslow Light amp Bose-Einstein Condensates Two-way Control with Coherent Light amp Atom

Fields Harvard Hau Lab Dr Lene Vestergaard Hau Optics amp Photonics News 16 1995

[6] The Art of Taming Light Ultra-slow and Stopped Light Harvard Hau Lab Dr Lene

Vestergaard Hau Europhysics News 2004

[7] Nonlinear Optics Shocking Superfluids Harvard Hau Lab Dr Lene Vestergaard Hau Nature

Physics 2007

[8] Model P3 Strain Indicator and Recorder Instruction Manual Vishay Micro-Measurements 2005

[9] Granville-Phillips Series 375 Convectron Vacuum Gauge Controller Instruction Manual Brooks

Automation 2008

[10] Effect of Film Thickness on the Validity of the Sauerbrey Equation for Hydrated Polyelectrolyte

Films Vogt Lin Wu White 2004

[11] Quartz Crystal Microbalance Study of DNA Immobilization and Hybridization for DNA Sensor

Development Chang Zhao 2008

[12] Installation of Strain Gages with SR-4 PrecoatAdhesive Vishay Micro-Measurements 2005

[13] Strain Gauge Measurement ndash A Tutorial National Instruments 1998

[14] Correlation between Vickers Hardness Number and Yield Stress of Cold-Formed Products

Yavuz Tekkaya

[15] httpsenwikipediaorg

Page 74: PC Hinge Materials Testing and AR Laser Diode Coating

74

Stress-Strain Diagrams

0 2 4 6 8 10 12 14

-200

0

200

400

600

800

1000

1200

1400

1600

1800

應力 (MPa)

應變()

(a)

0 2 4 6 8 10

-200

0

200

400

600

800

1000

1200

1400

1600

應力

(MPa)

位移 ()

(b)

Fig 3-27 Stress-Strain Diagrams for (a) 3 Round Bar and (b) 5 Round Bar

(Note These curves were formulated using Visual Solutions Inc VisSim Software)

75

Cut-Off Area

(a)

(b)

Fig 3-28 Cut-Off Area of (a) 3 Round Bar and (b) 5 Round Bar

76

The force value (N) was retrieved from the Universal Testing Machine

The Poissonrsquos Ratio (ε) is calculated as

ε =

the values for the Poissonrsquos Ratio are in average around 0297

The Youngrsquos Modulus (E) is calculated as

E =

Where

Stress =

Cross-sectional Area =

where D is the Diameter

The value for D was in average around 1258 mm

The values shown by the computer because there is Slippage phenomena between the Clamp and the

specimen will not be taken into consideration for the elongation strain and Youngrsquos modulus and we will

refer to the values that we have meticulously calculated

77

Chapter 4 AR COATING IN DEPTH

41 Experimentrsquos Purpose and Principles

By means of a vacuum chamber and several other instruments we intend to apply Anti-Reflective

Coating using deposition process to a laser diode and in this way reduce its refraction so as to make it

lose less light in the process of amplification and we can control certain wavelengths we want produced

for certain desired applications in our case we are attempting to re-create a Bose-Einstein Condensate

An optimal BEC apparatus is shown in figure 4-1

Fig 4-1 BEC Apparatus

The main point of this experiment is to build a vacuum chamber system attach all the instrumentation

needed (Vacuum pump deposition meter and voltmeter) and use it to apply AR coating to a laser diode

After we have accomplished the AR coating other team will be in charge of designing the BEC apparatus

and use the results of our research

78

42 Experimentrsquos Equipment

421 Vacuum Chamber

For this research we designed a vacuum chamber whose main body is shown in figure 4-2 Its

dimensions are

Width 240 mm

Length 240 mm

Height 200 mm

Outer Diameter 4 in

Inner Diameter 15 in

Fig 4-2 Vacuum Chamber Main Body

The chamber is made up of 6 pass ways pass way A is the connection with the Laser Deposition

Equipment pass way B is the connection with the Turbo Pump and pass way C is for the connection with

the Deposition Source

A

C

B

79

Pass way C is for the deposition source as mentioned above This is a system where a thermal

resistance is heated by passing a high current through it which heats up a filament boat (made of tungsten)

where the material to be evaporated is place We control the temperature as such that the material will

evaporate and the heat will not cause the filament boat to crack

Because P = Isup2 R (where P is power I is current and R is resistance) to avoid the current to flow

where it is not desired we decided that the material for the Thermocouple shown in figure 4-3 should be

Copper ᴓ 63 mm We choose it that way because Copper has very good heat dissipation characteristics

and the resistance value is low It can reduce the value of the current enough to make the thermocouple to

create heat

Fig 4-3 Thermocouple

To the thermocouple we attach the tungsten filament boat We need to take notice of materials to be

used in this design because when using high current the tungsten filament boar will heat up and so the

material must be able to keep up with the heating potential of tungsten and has a low coefficient of heat

dissipation to avoid the tungsten to fail when heating up and therefore not evaporating Considering all

this we decide to use Stainless Steel

Because this clamp will be assembled inside the chamber after many revisions it was determined it

will have the shape shown in figure 4-4

Fig 4-4 Filament Boat Clamp Design

80

For the tungsten filament boat we bought the product from a distributor The dimensions are

Length 100 mm

Width 10 mm

Height 1 mm

Our thermocouple is 15 in but the pass way C is 4 in so we need to attach a Flange that connects

15in to 4in Because these specifications are quite difficult to achieve by Milling we had to use

electrical wire cutting

For the laser clamping system where the laser that is going to be AR coated will be placed will be

connected to pass way A the assembly is shown in figure 4-5 below

Fig 4-5 Cover Assembly

For this design we used an O-ring instead of a gasket so as to save time The design of the assembly

where the laser will be placed is shown in figure 4-6

Fig 4-6 Upper Cover Inner Assembly

D

E

F

81

Point D is the plate in the assembly where the laser diode will be fixed Because of the easy

processing we decide to use Aluminum and it is screwed to the top cover Point E is the connection for

the Quartz crystal resonator and it is designed in the same as point F in this way the results of the quartz

microbalance system will be more accurate in real time Point F is the final resting place for the laser

diode We use a Thor Labs Base with dimensions of ᴓ 9mm and ᴓ 56mm for two different size laser

diodes It just needs to be plugged in for easy installation

From figure 4-6 we know that the system needs signal system connections and because of the

change in temperature inside the chamber this could affect the functioning of the quartz microbalance so

we also need to install water tubes for cooling This is shown in figure 4-7 below

Fig 4-7 Diagram of Upper Cover Connections

In figure 4-8 we show the Feed through connections and their functions

Fig 4-8 Feed through Diagram

82

1 SQM-160 wire 5 Laser Connection 1 (Vin)

2 SQM-160 (G) 6 Laser Connection 2 (G)

3 K-Type-1 7 Laser Connection 3 (PD)

4 K-Type-2 8 Not In Use

The fully assembled chamber is shown in figure 4-9

Fig 4-9 Fully Assembled Chamber

422 Quartz Crystal Microbalance

For measuring the deposition on our target for coating we used the Inficon SQM-160 RateThickness

Monitor It is an easy to use instrument for measuring many types of thin-film coatings as shown in

figure 4-10

(a) Front Panel (b) Back Panel

Fig 4-10 Inficon SQM-160

83

Table 4-1 shows the technical specifications for this equipment

Number of sensors 2 Standard 4 additional optional

Sensor Frequency Range 40 MHz ~ 60 MHz

Reference Frequency Accuracy 002

Thickness Display Resolution 1 Aring

Thickness Resolution 015 Aring (Std) 0037 Aring (Hi Res)

Density of Stored Films 05-9999 gmcc

Tooling 10-399

Z-Factor 010-1000

Final Thickness 0000-9999k Aring

Measurement Period 15 to 2 sec

Simulation Mode Yes

Frequency Mode Yes

Rate Resolution 011 Arings

Dual Crystal Yes

Etch Mode Yes

Crystal Tooling 10-399

Crystal Fail Min Max 40 to 60 MHz 41 to 61 MHz

Power 100-120 200-240~plusmn10 nominal 20W

Operation Environment 0degC ~ 50degC

0 ~ 80 RH non-condensing

0 ~ 2000 meters

Class 1 Equipment

Pollution Degree 2

Rack Dimensions 885mm x 2127mm x 1969mm

Weight 27 kg

Table 4-1 Inficon SQM-160 RateThickness Monitor Specs

84

To the SQM-160 we need to connect an Oscillator We use the Sigma Instruments Remote Oscillator

Ser No 2 268 as shown in figure 4-11

Fig 4-11 Sigma Instruments Remote Oscillator

The connections diagram is shown in figure 4-12

Fig 4-12 SQM-160 Connections Diagram

85

423 Turbo Pump

For our experiments we used the Pfeiffer TCP 015 Electronic Drive Unit shown below in figure 4-13

Table 4-2 shows the technical specifications for this equipment

(a) Front Panel (b) Back Panel

Fig 4-13 Pfeiffer TCP 015 Electronic Drive

Connection Voltage (100V) 90-112

Mains Frequency 5060 Hz

Start-up Current 22 A

Nominal Frequency 1500 Hz

Rotation Speed 10V = 1500Hz plusmn2

Analog Output Current 10 V = 25 A plusmn 5

Rotation Speed Switchpoint 750 Hz

Works Setting 8 min

Permissible Ambient Temperature 0degC ~ 40degC

Dimensions Front Panel 1285mm x 1063mm

Insertion Length 227mm

Weight 27 Kg

Table 4-2 Pfeiffer TCP 015 Electronic Drive Specs

86

The connections diagram is shown in figure 4-14

Fig 4-14Connections Diagram for Pfeiffer TCP 015

To measure the pressure inside the chamber we use the Granville Phillips 375 Convectron Vacuum

Pressure Controller shown in figure 4-15

(a) Front Panel (b) Back Panel

Fig 4-15 Granville Phillips 375 Convectron

87

Its dimensions are shown in figure 4-16

Fig 4-16 Dimensions of Convectron

Table 4-3 shows the technical specifications for this equipment

Table 4-3 Granville Phillips 375 Convectron Vacuum Pressure Controller Specs

88

424 Multimeter

For our experiment we used the Keithley 2000 Digital Multimeter as shown in figure 4-17

(a) Front Panel (b) Back Panel

Fig 4-17 Keithley Model 2000 6-12-Digit Digital Multimeter

Its technical specifications are shown in table 4-4

Table 4-4 Keithley Model 2000 6-12-Digit Digital Multimeter Specs

89

43 Experiment Procedure

1 Connecting together the equipment and the chamber

(1) We first connect the resonator to the thickness monitor and connect the other side to the

chamber

(2) We now connect the flexible tubes to the turbo pump on one side and to the chamber on the

other

(3) We need to check that tubes are tightly connected to avoid any leaks in the vacuum pumping

process which will not allow us to get to our goal of Torr As shown in figure 4-18

(4) Connect the convectron to the system as shown in figure 4-19

Fig 4-18 checking for leaks using alcohol

Fig 4-19 Convectron attached to System

90

(5) Attach the clamps of the Multimeter to the bottom of the chamber as shown in figure 4-20

(6) Place the Quartz crystal in place

(7) Close tight vacuum chamber

(8) Connect all electrical appliances to power source

Fig 4-20 Multimeter Connections

2 Starting up the System

(1) We turn on all the devices as such Check all systems are ready to function Reset all values

that might be left over from previous tests

(2) Start the thickness monitor and set all values for this experiment In our case we got to testing

the system but not actual coating So we used the simulation mode of the thickness monitor as

shown in figure 4-21

Fig 4-21 Simulation Mode

91

(3) Start the turbo pump Make sure the lid on the vacuum chamber is tightly closed

(4) Start convectron and record initial pressure

(5) Start Multimeter and record initial current

3 Coating Process

(1) If we have the deposition material inside the filament boat the power source for the high

current must be started as well

(2) Record all initial values for thickness current pressure

(3) For an ideal experiment we need a thickness of around 101 nm a pressure of Torr and

a current of 300 A

44 Results

From previous experiments we have shown that we can turn a LED into a laser by means of AR

Coating In figure 4-22 shown below we can compare the actual results of a Diode before and after AR

coating From the blue line we can see that when the diode is at a current of 15mA its light will change

from LED to laser and if we look at the red line its critical current is around 30 to 35 mA

Fig 4-22 AR Coating Comparison for Laser Diodes

This means that the light emitted is not as strong as if the diode had been coated because inside the

chamber there must be some excitation first so the reflectivity of both sides inside the diode must be high

So because of the coating in one of the sides we have opened a door and let the light come out so the

critical current is risen as such and will be higher value than that of before the coating

92

In the following figures we can see the difference between before and after coating in a material The

thickness is around 1016 nm for this material

Fig 4-23 Before Coating

Fig 4-24 After Coating

93

Chapter 5 CONCLUSIONS AND RECOMMENDATIONS

51 Conclusions

For the first part of this independent study taking into consideration the data that came out of our

research and that sent by the provider we can say

1 SUM 23 after heat treatment will unexpectedly develop cracking in the middle of the tensile

testing process and suddenly break

2 Itrsquos possible that in the process of heat treatment to the SUM 23 material the treatment was not

uniform and this will create a pre-loaded moment force on one side that pushes on the other side

of the specimen resulting in material deformation

3 In the process of attaching the strain gauges to the materials it is very easy to make errors due to

poor adhesion or sudden removal in the tensile testing process

For our second part of the independent study the following can be made

1 At the beginning of this independent study we had no idea what Bose-Einstein Condensate was

or what was its purpose After much literature we finally comprehended the basic principles to

put into practice for our research

2 Our systemrsquos basic working principles and equipmentrsquos complexity are a little difficult to grasp

but hopefully we were able to understand enough of it

3 Theoretically from relation between the power and current we can know the advantages and

disadvantages of AR Coating

4 We were able to assemble the system and run test on its functions Even though we were able to

do this there is still much more work left to do with this system

52 Recommendations

For the Tensile Testing the following can be said

1 Ask the provider to check on the process of heat treatment on the SUM 23 material and give

them the information we have gathered through our test so they can correct for the mechanical

properties found if any change is needed

2 To avoid the problem of the inaccuracy of the poor adhesion of strain gauges we can attach

multiple strain gauges to the same one specimen so as to correlate data and improve our results

For the AR Coating the following can be said

1 We need to make sure that there are no physical defects on the main body of the chamber so as to

achieve maximum efficiency in the vacuum process If there was then the vacuum will arrive to

certain point and then start to decrease

2 It would be preferable to add some sort of visual aid that will allow the user to check the inside of

the chamber without actually opening it This will help us determine at what times we should

manipulate the current to better evaporate the substrate

94

REFERENCES

[1] A L Window Strain Gauge Technology Elsevier Applied Science London and New York 2nd

Edition 1992

[2] CC Perry and HR Lissner Strain Gauge Primer McGraw-Hill Book Co Inc New York 1955

[3] James W Dally William F Riley McGraw-Hill 1978

[4] University of Colorado Boulder BEC - What is it and where did the idea come from

httpwwwcoloradoeduphysics2000becwhat_is_ithtml

[5] Ultraslow Light amp Bose-Einstein Condensates Two-way Control with Coherent Light amp Atom

Fields Harvard Hau Lab Dr Lene Vestergaard Hau Optics amp Photonics News 16 1995

[6] The Art of Taming Light Ultra-slow and Stopped Light Harvard Hau Lab Dr Lene

Vestergaard Hau Europhysics News 2004

[7] Nonlinear Optics Shocking Superfluids Harvard Hau Lab Dr Lene Vestergaard Hau Nature

Physics 2007

[8] Model P3 Strain Indicator and Recorder Instruction Manual Vishay Micro-Measurements 2005

[9] Granville-Phillips Series 375 Convectron Vacuum Gauge Controller Instruction Manual Brooks

Automation 2008

[10] Effect of Film Thickness on the Validity of the Sauerbrey Equation for Hydrated Polyelectrolyte

Films Vogt Lin Wu White 2004

[11] Quartz Crystal Microbalance Study of DNA Immobilization and Hybridization for DNA Sensor

Development Chang Zhao 2008

[12] Installation of Strain Gages with SR-4 PrecoatAdhesive Vishay Micro-Measurements 2005

[13] Strain Gauge Measurement ndash A Tutorial National Instruments 1998

[14] Correlation between Vickers Hardness Number and Yield Stress of Cold-Formed Products

Yavuz Tekkaya

[15] httpsenwikipediaorg

Page 75: PC Hinge Materials Testing and AR Laser Diode Coating

75

Cut-Off Area

(a)

(b)

Fig 3-28 Cut-Off Area of (a) 3 Round Bar and (b) 5 Round Bar

76

The force value (N) was retrieved from the Universal Testing Machine

The Poissonrsquos Ratio (ε) is calculated as

ε =

the values for the Poissonrsquos Ratio are in average around 0297

The Youngrsquos Modulus (E) is calculated as

E =

Where

Stress =

Cross-sectional Area =

where D is the Diameter

The value for D was in average around 1258 mm

The values shown by the computer because there is Slippage phenomena between the Clamp and the

specimen will not be taken into consideration for the elongation strain and Youngrsquos modulus and we will

refer to the values that we have meticulously calculated

77

Chapter 4 AR COATING IN DEPTH

41 Experimentrsquos Purpose and Principles

By means of a vacuum chamber and several other instruments we intend to apply Anti-Reflective

Coating using deposition process to a laser diode and in this way reduce its refraction so as to make it

lose less light in the process of amplification and we can control certain wavelengths we want produced

for certain desired applications in our case we are attempting to re-create a Bose-Einstein Condensate

An optimal BEC apparatus is shown in figure 4-1

Fig 4-1 BEC Apparatus

The main point of this experiment is to build a vacuum chamber system attach all the instrumentation

needed (Vacuum pump deposition meter and voltmeter) and use it to apply AR coating to a laser diode

After we have accomplished the AR coating other team will be in charge of designing the BEC apparatus

and use the results of our research

78

42 Experimentrsquos Equipment

421 Vacuum Chamber

For this research we designed a vacuum chamber whose main body is shown in figure 4-2 Its

dimensions are

Width 240 mm

Length 240 mm

Height 200 mm

Outer Diameter 4 in

Inner Diameter 15 in

Fig 4-2 Vacuum Chamber Main Body

The chamber is made up of 6 pass ways pass way A is the connection with the Laser Deposition

Equipment pass way B is the connection with the Turbo Pump and pass way C is for the connection with

the Deposition Source

A

C

B

79

Pass way C is for the deposition source as mentioned above This is a system where a thermal

resistance is heated by passing a high current through it which heats up a filament boat (made of tungsten)

where the material to be evaporated is place We control the temperature as such that the material will

evaporate and the heat will not cause the filament boat to crack

Because P = Isup2 R (where P is power I is current and R is resistance) to avoid the current to flow

where it is not desired we decided that the material for the Thermocouple shown in figure 4-3 should be

Copper ᴓ 63 mm We choose it that way because Copper has very good heat dissipation characteristics

and the resistance value is low It can reduce the value of the current enough to make the thermocouple to

create heat

Fig 4-3 Thermocouple

To the thermocouple we attach the tungsten filament boat We need to take notice of materials to be

used in this design because when using high current the tungsten filament boar will heat up and so the

material must be able to keep up with the heating potential of tungsten and has a low coefficient of heat

dissipation to avoid the tungsten to fail when heating up and therefore not evaporating Considering all

this we decide to use Stainless Steel

Because this clamp will be assembled inside the chamber after many revisions it was determined it

will have the shape shown in figure 4-4

Fig 4-4 Filament Boat Clamp Design

80

For the tungsten filament boat we bought the product from a distributor The dimensions are

Length 100 mm

Width 10 mm

Height 1 mm

Our thermocouple is 15 in but the pass way C is 4 in so we need to attach a Flange that connects

15in to 4in Because these specifications are quite difficult to achieve by Milling we had to use

electrical wire cutting

For the laser clamping system where the laser that is going to be AR coated will be placed will be

connected to pass way A the assembly is shown in figure 4-5 below

Fig 4-5 Cover Assembly

For this design we used an O-ring instead of a gasket so as to save time The design of the assembly

where the laser will be placed is shown in figure 4-6

Fig 4-6 Upper Cover Inner Assembly

D

E

F

81

Point D is the plate in the assembly where the laser diode will be fixed Because of the easy

processing we decide to use Aluminum and it is screwed to the top cover Point E is the connection for

the Quartz crystal resonator and it is designed in the same as point F in this way the results of the quartz

microbalance system will be more accurate in real time Point F is the final resting place for the laser

diode We use a Thor Labs Base with dimensions of ᴓ 9mm and ᴓ 56mm for two different size laser

diodes It just needs to be plugged in for easy installation

From figure 4-6 we know that the system needs signal system connections and because of the

change in temperature inside the chamber this could affect the functioning of the quartz microbalance so

we also need to install water tubes for cooling This is shown in figure 4-7 below

Fig 4-7 Diagram of Upper Cover Connections

In figure 4-8 we show the Feed through connections and their functions

Fig 4-8 Feed through Diagram

82

1 SQM-160 wire 5 Laser Connection 1 (Vin)

2 SQM-160 (G) 6 Laser Connection 2 (G)

3 K-Type-1 7 Laser Connection 3 (PD)

4 K-Type-2 8 Not In Use

The fully assembled chamber is shown in figure 4-9

Fig 4-9 Fully Assembled Chamber

422 Quartz Crystal Microbalance

For measuring the deposition on our target for coating we used the Inficon SQM-160 RateThickness

Monitor It is an easy to use instrument for measuring many types of thin-film coatings as shown in

figure 4-10

(a) Front Panel (b) Back Panel

Fig 4-10 Inficon SQM-160

83

Table 4-1 shows the technical specifications for this equipment

Number of sensors 2 Standard 4 additional optional

Sensor Frequency Range 40 MHz ~ 60 MHz

Reference Frequency Accuracy 002

Thickness Display Resolution 1 Aring

Thickness Resolution 015 Aring (Std) 0037 Aring (Hi Res)

Density of Stored Films 05-9999 gmcc

Tooling 10-399

Z-Factor 010-1000

Final Thickness 0000-9999k Aring

Measurement Period 15 to 2 sec

Simulation Mode Yes

Frequency Mode Yes

Rate Resolution 011 Arings

Dual Crystal Yes

Etch Mode Yes

Crystal Tooling 10-399

Crystal Fail Min Max 40 to 60 MHz 41 to 61 MHz

Power 100-120 200-240~plusmn10 nominal 20W

Operation Environment 0degC ~ 50degC

0 ~ 80 RH non-condensing

0 ~ 2000 meters

Class 1 Equipment

Pollution Degree 2

Rack Dimensions 885mm x 2127mm x 1969mm

Weight 27 kg

Table 4-1 Inficon SQM-160 RateThickness Monitor Specs

84

To the SQM-160 we need to connect an Oscillator We use the Sigma Instruments Remote Oscillator

Ser No 2 268 as shown in figure 4-11

Fig 4-11 Sigma Instruments Remote Oscillator

The connections diagram is shown in figure 4-12

Fig 4-12 SQM-160 Connections Diagram

85

423 Turbo Pump

For our experiments we used the Pfeiffer TCP 015 Electronic Drive Unit shown below in figure 4-13

Table 4-2 shows the technical specifications for this equipment

(a) Front Panel (b) Back Panel

Fig 4-13 Pfeiffer TCP 015 Electronic Drive

Connection Voltage (100V) 90-112

Mains Frequency 5060 Hz

Start-up Current 22 A

Nominal Frequency 1500 Hz

Rotation Speed 10V = 1500Hz plusmn2

Analog Output Current 10 V = 25 A plusmn 5

Rotation Speed Switchpoint 750 Hz

Works Setting 8 min

Permissible Ambient Temperature 0degC ~ 40degC

Dimensions Front Panel 1285mm x 1063mm

Insertion Length 227mm

Weight 27 Kg

Table 4-2 Pfeiffer TCP 015 Electronic Drive Specs

86

The connections diagram is shown in figure 4-14

Fig 4-14Connections Diagram for Pfeiffer TCP 015

To measure the pressure inside the chamber we use the Granville Phillips 375 Convectron Vacuum

Pressure Controller shown in figure 4-15

(a) Front Panel (b) Back Panel

Fig 4-15 Granville Phillips 375 Convectron

87

Its dimensions are shown in figure 4-16

Fig 4-16 Dimensions of Convectron

Table 4-3 shows the technical specifications for this equipment

Table 4-3 Granville Phillips 375 Convectron Vacuum Pressure Controller Specs

88

424 Multimeter

For our experiment we used the Keithley 2000 Digital Multimeter as shown in figure 4-17

(a) Front Panel (b) Back Panel

Fig 4-17 Keithley Model 2000 6-12-Digit Digital Multimeter

Its technical specifications are shown in table 4-4

Table 4-4 Keithley Model 2000 6-12-Digit Digital Multimeter Specs

89

43 Experiment Procedure

1 Connecting together the equipment and the chamber

(1) We first connect the resonator to the thickness monitor and connect the other side to the

chamber

(2) We now connect the flexible tubes to the turbo pump on one side and to the chamber on the

other

(3) We need to check that tubes are tightly connected to avoid any leaks in the vacuum pumping

process which will not allow us to get to our goal of Torr As shown in figure 4-18

(4) Connect the convectron to the system as shown in figure 4-19

Fig 4-18 checking for leaks using alcohol

Fig 4-19 Convectron attached to System

90

(5) Attach the clamps of the Multimeter to the bottom of the chamber as shown in figure 4-20

(6) Place the Quartz crystal in place

(7) Close tight vacuum chamber

(8) Connect all electrical appliances to power source

Fig 4-20 Multimeter Connections

2 Starting up the System

(1) We turn on all the devices as such Check all systems are ready to function Reset all values

that might be left over from previous tests

(2) Start the thickness monitor and set all values for this experiment In our case we got to testing

the system but not actual coating So we used the simulation mode of the thickness monitor as

shown in figure 4-21

Fig 4-21 Simulation Mode

91

(3) Start the turbo pump Make sure the lid on the vacuum chamber is tightly closed

(4) Start convectron and record initial pressure

(5) Start Multimeter and record initial current

3 Coating Process

(1) If we have the deposition material inside the filament boat the power source for the high

current must be started as well

(2) Record all initial values for thickness current pressure

(3) For an ideal experiment we need a thickness of around 101 nm a pressure of Torr and

a current of 300 A

44 Results

From previous experiments we have shown that we can turn a LED into a laser by means of AR

Coating In figure 4-22 shown below we can compare the actual results of a Diode before and after AR

coating From the blue line we can see that when the diode is at a current of 15mA its light will change

from LED to laser and if we look at the red line its critical current is around 30 to 35 mA

Fig 4-22 AR Coating Comparison for Laser Diodes

This means that the light emitted is not as strong as if the diode had been coated because inside the

chamber there must be some excitation first so the reflectivity of both sides inside the diode must be high

So because of the coating in one of the sides we have opened a door and let the light come out so the

critical current is risen as such and will be higher value than that of before the coating

92

In the following figures we can see the difference between before and after coating in a material The

thickness is around 1016 nm for this material

Fig 4-23 Before Coating

Fig 4-24 After Coating

93

Chapter 5 CONCLUSIONS AND RECOMMENDATIONS

51 Conclusions

For the first part of this independent study taking into consideration the data that came out of our

research and that sent by the provider we can say

1 SUM 23 after heat treatment will unexpectedly develop cracking in the middle of the tensile

testing process and suddenly break

2 Itrsquos possible that in the process of heat treatment to the SUM 23 material the treatment was not

uniform and this will create a pre-loaded moment force on one side that pushes on the other side

of the specimen resulting in material deformation

3 In the process of attaching the strain gauges to the materials it is very easy to make errors due to

poor adhesion or sudden removal in the tensile testing process

For our second part of the independent study the following can be made

1 At the beginning of this independent study we had no idea what Bose-Einstein Condensate was

or what was its purpose After much literature we finally comprehended the basic principles to

put into practice for our research

2 Our systemrsquos basic working principles and equipmentrsquos complexity are a little difficult to grasp

but hopefully we were able to understand enough of it

3 Theoretically from relation between the power and current we can know the advantages and

disadvantages of AR Coating

4 We were able to assemble the system and run test on its functions Even though we were able to

do this there is still much more work left to do with this system

52 Recommendations

For the Tensile Testing the following can be said

1 Ask the provider to check on the process of heat treatment on the SUM 23 material and give

them the information we have gathered through our test so they can correct for the mechanical

properties found if any change is needed

2 To avoid the problem of the inaccuracy of the poor adhesion of strain gauges we can attach

multiple strain gauges to the same one specimen so as to correlate data and improve our results

For the AR Coating the following can be said

1 We need to make sure that there are no physical defects on the main body of the chamber so as to

achieve maximum efficiency in the vacuum process If there was then the vacuum will arrive to

certain point and then start to decrease

2 It would be preferable to add some sort of visual aid that will allow the user to check the inside of

the chamber without actually opening it This will help us determine at what times we should

manipulate the current to better evaporate the substrate

94

REFERENCES

[1] A L Window Strain Gauge Technology Elsevier Applied Science London and New York 2nd

Edition 1992

[2] CC Perry and HR Lissner Strain Gauge Primer McGraw-Hill Book Co Inc New York 1955

[3] James W Dally William F Riley McGraw-Hill 1978

[4] University of Colorado Boulder BEC - What is it and where did the idea come from

httpwwwcoloradoeduphysics2000becwhat_is_ithtml

[5] Ultraslow Light amp Bose-Einstein Condensates Two-way Control with Coherent Light amp Atom

Fields Harvard Hau Lab Dr Lene Vestergaard Hau Optics amp Photonics News 16 1995

[6] The Art of Taming Light Ultra-slow and Stopped Light Harvard Hau Lab Dr Lene

Vestergaard Hau Europhysics News 2004

[7] Nonlinear Optics Shocking Superfluids Harvard Hau Lab Dr Lene Vestergaard Hau Nature

Physics 2007

[8] Model P3 Strain Indicator and Recorder Instruction Manual Vishay Micro-Measurements 2005

[9] Granville-Phillips Series 375 Convectron Vacuum Gauge Controller Instruction Manual Brooks

Automation 2008

[10] Effect of Film Thickness on the Validity of the Sauerbrey Equation for Hydrated Polyelectrolyte

Films Vogt Lin Wu White 2004

[11] Quartz Crystal Microbalance Study of DNA Immobilization and Hybridization for DNA Sensor

Development Chang Zhao 2008

[12] Installation of Strain Gages with SR-4 PrecoatAdhesive Vishay Micro-Measurements 2005

[13] Strain Gauge Measurement ndash A Tutorial National Instruments 1998

[14] Correlation between Vickers Hardness Number and Yield Stress of Cold-Formed Products

Yavuz Tekkaya

[15] httpsenwikipediaorg

Page 76: PC Hinge Materials Testing and AR Laser Diode Coating

76

The force value (N) was retrieved from the Universal Testing Machine

The Poissonrsquos Ratio (ε) is calculated as

ε =

the values for the Poissonrsquos Ratio are in average around 0297

The Youngrsquos Modulus (E) is calculated as

E =

Where

Stress =

Cross-sectional Area =

where D is the Diameter

The value for D was in average around 1258 mm

The values shown by the computer because there is Slippage phenomena between the Clamp and the

specimen will not be taken into consideration for the elongation strain and Youngrsquos modulus and we will

refer to the values that we have meticulously calculated

77

Chapter 4 AR COATING IN DEPTH

41 Experimentrsquos Purpose and Principles

By means of a vacuum chamber and several other instruments we intend to apply Anti-Reflective

Coating using deposition process to a laser diode and in this way reduce its refraction so as to make it

lose less light in the process of amplification and we can control certain wavelengths we want produced

for certain desired applications in our case we are attempting to re-create a Bose-Einstein Condensate

An optimal BEC apparatus is shown in figure 4-1

Fig 4-1 BEC Apparatus

The main point of this experiment is to build a vacuum chamber system attach all the instrumentation

needed (Vacuum pump deposition meter and voltmeter) and use it to apply AR coating to a laser diode

After we have accomplished the AR coating other team will be in charge of designing the BEC apparatus

and use the results of our research

78

42 Experimentrsquos Equipment

421 Vacuum Chamber

For this research we designed a vacuum chamber whose main body is shown in figure 4-2 Its

dimensions are

Width 240 mm

Length 240 mm

Height 200 mm

Outer Diameter 4 in

Inner Diameter 15 in

Fig 4-2 Vacuum Chamber Main Body

The chamber is made up of 6 pass ways pass way A is the connection with the Laser Deposition

Equipment pass way B is the connection with the Turbo Pump and pass way C is for the connection with

the Deposition Source

A

C

B

79

Pass way C is for the deposition source as mentioned above This is a system where a thermal

resistance is heated by passing a high current through it which heats up a filament boat (made of tungsten)

where the material to be evaporated is place We control the temperature as such that the material will

evaporate and the heat will not cause the filament boat to crack

Because P = Isup2 R (where P is power I is current and R is resistance) to avoid the current to flow

where it is not desired we decided that the material for the Thermocouple shown in figure 4-3 should be

Copper ᴓ 63 mm We choose it that way because Copper has very good heat dissipation characteristics

and the resistance value is low It can reduce the value of the current enough to make the thermocouple to

create heat

Fig 4-3 Thermocouple

To the thermocouple we attach the tungsten filament boat We need to take notice of materials to be

used in this design because when using high current the tungsten filament boar will heat up and so the

material must be able to keep up with the heating potential of tungsten and has a low coefficient of heat

dissipation to avoid the tungsten to fail when heating up and therefore not evaporating Considering all

this we decide to use Stainless Steel

Because this clamp will be assembled inside the chamber after many revisions it was determined it

will have the shape shown in figure 4-4

Fig 4-4 Filament Boat Clamp Design

80

For the tungsten filament boat we bought the product from a distributor The dimensions are

Length 100 mm

Width 10 mm

Height 1 mm

Our thermocouple is 15 in but the pass way C is 4 in so we need to attach a Flange that connects

15in to 4in Because these specifications are quite difficult to achieve by Milling we had to use

electrical wire cutting

For the laser clamping system where the laser that is going to be AR coated will be placed will be

connected to pass way A the assembly is shown in figure 4-5 below

Fig 4-5 Cover Assembly

For this design we used an O-ring instead of a gasket so as to save time The design of the assembly

where the laser will be placed is shown in figure 4-6

Fig 4-6 Upper Cover Inner Assembly

D

E

F

81

Point D is the plate in the assembly where the laser diode will be fixed Because of the easy

processing we decide to use Aluminum and it is screwed to the top cover Point E is the connection for

the Quartz crystal resonator and it is designed in the same as point F in this way the results of the quartz

microbalance system will be more accurate in real time Point F is the final resting place for the laser

diode We use a Thor Labs Base with dimensions of ᴓ 9mm and ᴓ 56mm for two different size laser

diodes It just needs to be plugged in for easy installation

From figure 4-6 we know that the system needs signal system connections and because of the

change in temperature inside the chamber this could affect the functioning of the quartz microbalance so

we also need to install water tubes for cooling This is shown in figure 4-7 below

Fig 4-7 Diagram of Upper Cover Connections

In figure 4-8 we show the Feed through connections and their functions

Fig 4-8 Feed through Diagram

82

1 SQM-160 wire 5 Laser Connection 1 (Vin)

2 SQM-160 (G) 6 Laser Connection 2 (G)

3 K-Type-1 7 Laser Connection 3 (PD)

4 K-Type-2 8 Not In Use

The fully assembled chamber is shown in figure 4-9

Fig 4-9 Fully Assembled Chamber

422 Quartz Crystal Microbalance

For measuring the deposition on our target for coating we used the Inficon SQM-160 RateThickness

Monitor It is an easy to use instrument for measuring many types of thin-film coatings as shown in

figure 4-10

(a) Front Panel (b) Back Panel

Fig 4-10 Inficon SQM-160

83

Table 4-1 shows the technical specifications for this equipment

Number of sensors 2 Standard 4 additional optional

Sensor Frequency Range 40 MHz ~ 60 MHz

Reference Frequency Accuracy 002

Thickness Display Resolution 1 Aring

Thickness Resolution 015 Aring (Std) 0037 Aring (Hi Res)

Density of Stored Films 05-9999 gmcc

Tooling 10-399

Z-Factor 010-1000

Final Thickness 0000-9999k Aring

Measurement Period 15 to 2 sec

Simulation Mode Yes

Frequency Mode Yes

Rate Resolution 011 Arings

Dual Crystal Yes

Etch Mode Yes

Crystal Tooling 10-399

Crystal Fail Min Max 40 to 60 MHz 41 to 61 MHz

Power 100-120 200-240~plusmn10 nominal 20W

Operation Environment 0degC ~ 50degC

0 ~ 80 RH non-condensing

0 ~ 2000 meters

Class 1 Equipment

Pollution Degree 2

Rack Dimensions 885mm x 2127mm x 1969mm

Weight 27 kg

Table 4-1 Inficon SQM-160 RateThickness Monitor Specs

84

To the SQM-160 we need to connect an Oscillator We use the Sigma Instruments Remote Oscillator

Ser No 2 268 as shown in figure 4-11

Fig 4-11 Sigma Instruments Remote Oscillator

The connections diagram is shown in figure 4-12

Fig 4-12 SQM-160 Connections Diagram

85

423 Turbo Pump

For our experiments we used the Pfeiffer TCP 015 Electronic Drive Unit shown below in figure 4-13

Table 4-2 shows the technical specifications for this equipment

(a) Front Panel (b) Back Panel

Fig 4-13 Pfeiffer TCP 015 Electronic Drive

Connection Voltage (100V) 90-112

Mains Frequency 5060 Hz

Start-up Current 22 A

Nominal Frequency 1500 Hz

Rotation Speed 10V = 1500Hz plusmn2

Analog Output Current 10 V = 25 A plusmn 5

Rotation Speed Switchpoint 750 Hz

Works Setting 8 min

Permissible Ambient Temperature 0degC ~ 40degC

Dimensions Front Panel 1285mm x 1063mm

Insertion Length 227mm

Weight 27 Kg

Table 4-2 Pfeiffer TCP 015 Electronic Drive Specs

86

The connections diagram is shown in figure 4-14

Fig 4-14Connections Diagram for Pfeiffer TCP 015

To measure the pressure inside the chamber we use the Granville Phillips 375 Convectron Vacuum

Pressure Controller shown in figure 4-15

(a) Front Panel (b) Back Panel

Fig 4-15 Granville Phillips 375 Convectron

87

Its dimensions are shown in figure 4-16

Fig 4-16 Dimensions of Convectron

Table 4-3 shows the technical specifications for this equipment

Table 4-3 Granville Phillips 375 Convectron Vacuum Pressure Controller Specs

88

424 Multimeter

For our experiment we used the Keithley 2000 Digital Multimeter as shown in figure 4-17

(a) Front Panel (b) Back Panel

Fig 4-17 Keithley Model 2000 6-12-Digit Digital Multimeter

Its technical specifications are shown in table 4-4

Table 4-4 Keithley Model 2000 6-12-Digit Digital Multimeter Specs

89

43 Experiment Procedure

1 Connecting together the equipment and the chamber

(1) We first connect the resonator to the thickness monitor and connect the other side to the

chamber

(2) We now connect the flexible tubes to the turbo pump on one side and to the chamber on the

other

(3) We need to check that tubes are tightly connected to avoid any leaks in the vacuum pumping

process which will not allow us to get to our goal of Torr As shown in figure 4-18

(4) Connect the convectron to the system as shown in figure 4-19

Fig 4-18 checking for leaks using alcohol

Fig 4-19 Convectron attached to System

90

(5) Attach the clamps of the Multimeter to the bottom of the chamber as shown in figure 4-20

(6) Place the Quartz crystal in place

(7) Close tight vacuum chamber

(8) Connect all electrical appliances to power source

Fig 4-20 Multimeter Connections

2 Starting up the System

(1) We turn on all the devices as such Check all systems are ready to function Reset all values

that might be left over from previous tests

(2) Start the thickness monitor and set all values for this experiment In our case we got to testing

the system but not actual coating So we used the simulation mode of the thickness monitor as

shown in figure 4-21

Fig 4-21 Simulation Mode

91

(3) Start the turbo pump Make sure the lid on the vacuum chamber is tightly closed

(4) Start convectron and record initial pressure

(5) Start Multimeter and record initial current

3 Coating Process

(1) If we have the deposition material inside the filament boat the power source for the high

current must be started as well

(2) Record all initial values for thickness current pressure

(3) For an ideal experiment we need a thickness of around 101 nm a pressure of Torr and

a current of 300 A

44 Results

From previous experiments we have shown that we can turn a LED into a laser by means of AR

Coating In figure 4-22 shown below we can compare the actual results of a Diode before and after AR

coating From the blue line we can see that when the diode is at a current of 15mA its light will change

from LED to laser and if we look at the red line its critical current is around 30 to 35 mA

Fig 4-22 AR Coating Comparison for Laser Diodes

This means that the light emitted is not as strong as if the diode had been coated because inside the

chamber there must be some excitation first so the reflectivity of both sides inside the diode must be high

So because of the coating in one of the sides we have opened a door and let the light come out so the

critical current is risen as such and will be higher value than that of before the coating

92

In the following figures we can see the difference between before and after coating in a material The

thickness is around 1016 nm for this material

Fig 4-23 Before Coating

Fig 4-24 After Coating

93

Chapter 5 CONCLUSIONS AND RECOMMENDATIONS

51 Conclusions

For the first part of this independent study taking into consideration the data that came out of our

research and that sent by the provider we can say

1 SUM 23 after heat treatment will unexpectedly develop cracking in the middle of the tensile

testing process and suddenly break

2 Itrsquos possible that in the process of heat treatment to the SUM 23 material the treatment was not

uniform and this will create a pre-loaded moment force on one side that pushes on the other side

of the specimen resulting in material deformation

3 In the process of attaching the strain gauges to the materials it is very easy to make errors due to

poor adhesion or sudden removal in the tensile testing process

For our second part of the independent study the following can be made

1 At the beginning of this independent study we had no idea what Bose-Einstein Condensate was

or what was its purpose After much literature we finally comprehended the basic principles to

put into practice for our research

2 Our systemrsquos basic working principles and equipmentrsquos complexity are a little difficult to grasp

but hopefully we were able to understand enough of it

3 Theoretically from relation between the power and current we can know the advantages and

disadvantages of AR Coating

4 We were able to assemble the system and run test on its functions Even though we were able to

do this there is still much more work left to do with this system

52 Recommendations

For the Tensile Testing the following can be said

1 Ask the provider to check on the process of heat treatment on the SUM 23 material and give

them the information we have gathered through our test so they can correct for the mechanical

properties found if any change is needed

2 To avoid the problem of the inaccuracy of the poor adhesion of strain gauges we can attach

multiple strain gauges to the same one specimen so as to correlate data and improve our results

For the AR Coating the following can be said

1 We need to make sure that there are no physical defects on the main body of the chamber so as to

achieve maximum efficiency in the vacuum process If there was then the vacuum will arrive to

certain point and then start to decrease

2 It would be preferable to add some sort of visual aid that will allow the user to check the inside of

the chamber without actually opening it This will help us determine at what times we should

manipulate the current to better evaporate the substrate

94

REFERENCES

[1] A L Window Strain Gauge Technology Elsevier Applied Science London and New York 2nd

Edition 1992

[2] CC Perry and HR Lissner Strain Gauge Primer McGraw-Hill Book Co Inc New York 1955

[3] James W Dally William F Riley McGraw-Hill 1978

[4] University of Colorado Boulder BEC - What is it and where did the idea come from

httpwwwcoloradoeduphysics2000becwhat_is_ithtml

[5] Ultraslow Light amp Bose-Einstein Condensates Two-way Control with Coherent Light amp Atom

Fields Harvard Hau Lab Dr Lene Vestergaard Hau Optics amp Photonics News 16 1995

[6] The Art of Taming Light Ultra-slow and Stopped Light Harvard Hau Lab Dr Lene

Vestergaard Hau Europhysics News 2004

[7] Nonlinear Optics Shocking Superfluids Harvard Hau Lab Dr Lene Vestergaard Hau Nature

Physics 2007

[8] Model P3 Strain Indicator and Recorder Instruction Manual Vishay Micro-Measurements 2005

[9] Granville-Phillips Series 375 Convectron Vacuum Gauge Controller Instruction Manual Brooks

Automation 2008

[10] Effect of Film Thickness on the Validity of the Sauerbrey Equation for Hydrated Polyelectrolyte

Films Vogt Lin Wu White 2004

[11] Quartz Crystal Microbalance Study of DNA Immobilization and Hybridization for DNA Sensor

Development Chang Zhao 2008

[12] Installation of Strain Gages with SR-4 PrecoatAdhesive Vishay Micro-Measurements 2005

[13] Strain Gauge Measurement ndash A Tutorial National Instruments 1998

[14] Correlation between Vickers Hardness Number and Yield Stress of Cold-Formed Products

Yavuz Tekkaya

[15] httpsenwikipediaorg

Page 77: PC Hinge Materials Testing and AR Laser Diode Coating

77

Chapter 4 AR COATING IN DEPTH

41 Experimentrsquos Purpose and Principles

By means of a vacuum chamber and several other instruments we intend to apply Anti-Reflective

Coating using deposition process to a laser diode and in this way reduce its refraction so as to make it

lose less light in the process of amplification and we can control certain wavelengths we want produced

for certain desired applications in our case we are attempting to re-create a Bose-Einstein Condensate

An optimal BEC apparatus is shown in figure 4-1

Fig 4-1 BEC Apparatus

The main point of this experiment is to build a vacuum chamber system attach all the instrumentation

needed (Vacuum pump deposition meter and voltmeter) and use it to apply AR coating to a laser diode

After we have accomplished the AR coating other team will be in charge of designing the BEC apparatus

and use the results of our research

78

42 Experimentrsquos Equipment

421 Vacuum Chamber

For this research we designed a vacuum chamber whose main body is shown in figure 4-2 Its

dimensions are

Width 240 mm

Length 240 mm

Height 200 mm

Outer Diameter 4 in

Inner Diameter 15 in

Fig 4-2 Vacuum Chamber Main Body

The chamber is made up of 6 pass ways pass way A is the connection with the Laser Deposition

Equipment pass way B is the connection with the Turbo Pump and pass way C is for the connection with

the Deposition Source

A

C

B

79

Pass way C is for the deposition source as mentioned above This is a system where a thermal

resistance is heated by passing a high current through it which heats up a filament boat (made of tungsten)

where the material to be evaporated is place We control the temperature as such that the material will

evaporate and the heat will not cause the filament boat to crack

Because P = Isup2 R (where P is power I is current and R is resistance) to avoid the current to flow

where it is not desired we decided that the material for the Thermocouple shown in figure 4-3 should be

Copper ᴓ 63 mm We choose it that way because Copper has very good heat dissipation characteristics

and the resistance value is low It can reduce the value of the current enough to make the thermocouple to

create heat

Fig 4-3 Thermocouple

To the thermocouple we attach the tungsten filament boat We need to take notice of materials to be

used in this design because when using high current the tungsten filament boar will heat up and so the

material must be able to keep up with the heating potential of tungsten and has a low coefficient of heat

dissipation to avoid the tungsten to fail when heating up and therefore not evaporating Considering all

this we decide to use Stainless Steel

Because this clamp will be assembled inside the chamber after many revisions it was determined it

will have the shape shown in figure 4-4

Fig 4-4 Filament Boat Clamp Design

80

For the tungsten filament boat we bought the product from a distributor The dimensions are

Length 100 mm

Width 10 mm

Height 1 mm

Our thermocouple is 15 in but the pass way C is 4 in so we need to attach a Flange that connects

15in to 4in Because these specifications are quite difficult to achieve by Milling we had to use

electrical wire cutting

For the laser clamping system where the laser that is going to be AR coated will be placed will be

connected to pass way A the assembly is shown in figure 4-5 below

Fig 4-5 Cover Assembly

For this design we used an O-ring instead of a gasket so as to save time The design of the assembly

where the laser will be placed is shown in figure 4-6

Fig 4-6 Upper Cover Inner Assembly

D

E

F

81

Point D is the plate in the assembly where the laser diode will be fixed Because of the easy

processing we decide to use Aluminum and it is screwed to the top cover Point E is the connection for

the Quartz crystal resonator and it is designed in the same as point F in this way the results of the quartz

microbalance system will be more accurate in real time Point F is the final resting place for the laser

diode We use a Thor Labs Base with dimensions of ᴓ 9mm and ᴓ 56mm for two different size laser

diodes It just needs to be plugged in for easy installation

From figure 4-6 we know that the system needs signal system connections and because of the

change in temperature inside the chamber this could affect the functioning of the quartz microbalance so

we also need to install water tubes for cooling This is shown in figure 4-7 below

Fig 4-7 Diagram of Upper Cover Connections

In figure 4-8 we show the Feed through connections and their functions

Fig 4-8 Feed through Diagram

82

1 SQM-160 wire 5 Laser Connection 1 (Vin)

2 SQM-160 (G) 6 Laser Connection 2 (G)

3 K-Type-1 7 Laser Connection 3 (PD)

4 K-Type-2 8 Not In Use

The fully assembled chamber is shown in figure 4-9

Fig 4-9 Fully Assembled Chamber

422 Quartz Crystal Microbalance

For measuring the deposition on our target for coating we used the Inficon SQM-160 RateThickness

Monitor It is an easy to use instrument for measuring many types of thin-film coatings as shown in

figure 4-10

(a) Front Panel (b) Back Panel

Fig 4-10 Inficon SQM-160

83

Table 4-1 shows the technical specifications for this equipment

Number of sensors 2 Standard 4 additional optional

Sensor Frequency Range 40 MHz ~ 60 MHz

Reference Frequency Accuracy 002

Thickness Display Resolution 1 Aring

Thickness Resolution 015 Aring (Std) 0037 Aring (Hi Res)

Density of Stored Films 05-9999 gmcc

Tooling 10-399

Z-Factor 010-1000

Final Thickness 0000-9999k Aring

Measurement Period 15 to 2 sec

Simulation Mode Yes

Frequency Mode Yes

Rate Resolution 011 Arings

Dual Crystal Yes

Etch Mode Yes

Crystal Tooling 10-399

Crystal Fail Min Max 40 to 60 MHz 41 to 61 MHz

Power 100-120 200-240~plusmn10 nominal 20W

Operation Environment 0degC ~ 50degC

0 ~ 80 RH non-condensing

0 ~ 2000 meters

Class 1 Equipment

Pollution Degree 2

Rack Dimensions 885mm x 2127mm x 1969mm

Weight 27 kg

Table 4-1 Inficon SQM-160 RateThickness Monitor Specs

84

To the SQM-160 we need to connect an Oscillator We use the Sigma Instruments Remote Oscillator

Ser No 2 268 as shown in figure 4-11

Fig 4-11 Sigma Instruments Remote Oscillator

The connections diagram is shown in figure 4-12

Fig 4-12 SQM-160 Connections Diagram

85

423 Turbo Pump

For our experiments we used the Pfeiffer TCP 015 Electronic Drive Unit shown below in figure 4-13

Table 4-2 shows the technical specifications for this equipment

(a) Front Panel (b) Back Panel

Fig 4-13 Pfeiffer TCP 015 Electronic Drive

Connection Voltage (100V) 90-112

Mains Frequency 5060 Hz

Start-up Current 22 A

Nominal Frequency 1500 Hz

Rotation Speed 10V = 1500Hz plusmn2

Analog Output Current 10 V = 25 A plusmn 5

Rotation Speed Switchpoint 750 Hz

Works Setting 8 min

Permissible Ambient Temperature 0degC ~ 40degC

Dimensions Front Panel 1285mm x 1063mm

Insertion Length 227mm

Weight 27 Kg

Table 4-2 Pfeiffer TCP 015 Electronic Drive Specs

86

The connections diagram is shown in figure 4-14

Fig 4-14Connections Diagram for Pfeiffer TCP 015

To measure the pressure inside the chamber we use the Granville Phillips 375 Convectron Vacuum

Pressure Controller shown in figure 4-15

(a) Front Panel (b) Back Panel

Fig 4-15 Granville Phillips 375 Convectron

87

Its dimensions are shown in figure 4-16

Fig 4-16 Dimensions of Convectron

Table 4-3 shows the technical specifications for this equipment

Table 4-3 Granville Phillips 375 Convectron Vacuum Pressure Controller Specs

88

424 Multimeter

For our experiment we used the Keithley 2000 Digital Multimeter as shown in figure 4-17

(a) Front Panel (b) Back Panel

Fig 4-17 Keithley Model 2000 6-12-Digit Digital Multimeter

Its technical specifications are shown in table 4-4

Table 4-4 Keithley Model 2000 6-12-Digit Digital Multimeter Specs

89

43 Experiment Procedure

1 Connecting together the equipment and the chamber

(1) We first connect the resonator to the thickness monitor and connect the other side to the

chamber

(2) We now connect the flexible tubes to the turbo pump on one side and to the chamber on the

other

(3) We need to check that tubes are tightly connected to avoid any leaks in the vacuum pumping

process which will not allow us to get to our goal of Torr As shown in figure 4-18

(4) Connect the convectron to the system as shown in figure 4-19

Fig 4-18 checking for leaks using alcohol

Fig 4-19 Convectron attached to System

90

(5) Attach the clamps of the Multimeter to the bottom of the chamber as shown in figure 4-20

(6) Place the Quartz crystal in place

(7) Close tight vacuum chamber

(8) Connect all electrical appliances to power source

Fig 4-20 Multimeter Connections

2 Starting up the System

(1) We turn on all the devices as such Check all systems are ready to function Reset all values

that might be left over from previous tests

(2) Start the thickness monitor and set all values for this experiment In our case we got to testing

the system but not actual coating So we used the simulation mode of the thickness monitor as

shown in figure 4-21

Fig 4-21 Simulation Mode

91

(3) Start the turbo pump Make sure the lid on the vacuum chamber is tightly closed

(4) Start convectron and record initial pressure

(5) Start Multimeter and record initial current

3 Coating Process

(1) If we have the deposition material inside the filament boat the power source for the high

current must be started as well

(2) Record all initial values for thickness current pressure

(3) For an ideal experiment we need a thickness of around 101 nm a pressure of Torr and

a current of 300 A

44 Results

From previous experiments we have shown that we can turn a LED into a laser by means of AR

Coating In figure 4-22 shown below we can compare the actual results of a Diode before and after AR

coating From the blue line we can see that when the diode is at a current of 15mA its light will change

from LED to laser and if we look at the red line its critical current is around 30 to 35 mA

Fig 4-22 AR Coating Comparison for Laser Diodes

This means that the light emitted is not as strong as if the diode had been coated because inside the

chamber there must be some excitation first so the reflectivity of both sides inside the diode must be high

So because of the coating in one of the sides we have opened a door and let the light come out so the

critical current is risen as such and will be higher value than that of before the coating

92

In the following figures we can see the difference between before and after coating in a material The

thickness is around 1016 nm for this material

Fig 4-23 Before Coating

Fig 4-24 After Coating

93

Chapter 5 CONCLUSIONS AND RECOMMENDATIONS

51 Conclusions

For the first part of this independent study taking into consideration the data that came out of our

research and that sent by the provider we can say

1 SUM 23 after heat treatment will unexpectedly develop cracking in the middle of the tensile

testing process and suddenly break

2 Itrsquos possible that in the process of heat treatment to the SUM 23 material the treatment was not

uniform and this will create a pre-loaded moment force on one side that pushes on the other side

of the specimen resulting in material deformation

3 In the process of attaching the strain gauges to the materials it is very easy to make errors due to

poor adhesion or sudden removal in the tensile testing process

For our second part of the independent study the following can be made

1 At the beginning of this independent study we had no idea what Bose-Einstein Condensate was

or what was its purpose After much literature we finally comprehended the basic principles to

put into practice for our research

2 Our systemrsquos basic working principles and equipmentrsquos complexity are a little difficult to grasp

but hopefully we were able to understand enough of it

3 Theoretically from relation between the power and current we can know the advantages and

disadvantages of AR Coating

4 We were able to assemble the system and run test on its functions Even though we were able to

do this there is still much more work left to do with this system

52 Recommendations

For the Tensile Testing the following can be said

1 Ask the provider to check on the process of heat treatment on the SUM 23 material and give

them the information we have gathered through our test so they can correct for the mechanical

properties found if any change is needed

2 To avoid the problem of the inaccuracy of the poor adhesion of strain gauges we can attach

multiple strain gauges to the same one specimen so as to correlate data and improve our results

For the AR Coating the following can be said

1 We need to make sure that there are no physical defects on the main body of the chamber so as to

achieve maximum efficiency in the vacuum process If there was then the vacuum will arrive to

certain point and then start to decrease

2 It would be preferable to add some sort of visual aid that will allow the user to check the inside of

the chamber without actually opening it This will help us determine at what times we should

manipulate the current to better evaporate the substrate

94

REFERENCES

[1] A L Window Strain Gauge Technology Elsevier Applied Science London and New York 2nd

Edition 1992

[2] CC Perry and HR Lissner Strain Gauge Primer McGraw-Hill Book Co Inc New York 1955

[3] James W Dally William F Riley McGraw-Hill 1978

[4] University of Colorado Boulder BEC - What is it and where did the idea come from

httpwwwcoloradoeduphysics2000becwhat_is_ithtml

[5] Ultraslow Light amp Bose-Einstein Condensates Two-way Control with Coherent Light amp Atom

Fields Harvard Hau Lab Dr Lene Vestergaard Hau Optics amp Photonics News 16 1995

[6] The Art of Taming Light Ultra-slow and Stopped Light Harvard Hau Lab Dr Lene

Vestergaard Hau Europhysics News 2004

[7] Nonlinear Optics Shocking Superfluids Harvard Hau Lab Dr Lene Vestergaard Hau Nature

Physics 2007

[8] Model P3 Strain Indicator and Recorder Instruction Manual Vishay Micro-Measurements 2005

[9] Granville-Phillips Series 375 Convectron Vacuum Gauge Controller Instruction Manual Brooks

Automation 2008

[10] Effect of Film Thickness on the Validity of the Sauerbrey Equation for Hydrated Polyelectrolyte

Films Vogt Lin Wu White 2004

[11] Quartz Crystal Microbalance Study of DNA Immobilization and Hybridization for DNA Sensor

Development Chang Zhao 2008

[12] Installation of Strain Gages with SR-4 PrecoatAdhesive Vishay Micro-Measurements 2005

[13] Strain Gauge Measurement ndash A Tutorial National Instruments 1998

[14] Correlation between Vickers Hardness Number and Yield Stress of Cold-Formed Products

Yavuz Tekkaya

[15] httpsenwikipediaorg

Page 78: PC Hinge Materials Testing and AR Laser Diode Coating

78

42 Experimentrsquos Equipment

421 Vacuum Chamber

For this research we designed a vacuum chamber whose main body is shown in figure 4-2 Its

dimensions are

Width 240 mm

Length 240 mm

Height 200 mm

Outer Diameter 4 in

Inner Diameter 15 in

Fig 4-2 Vacuum Chamber Main Body

The chamber is made up of 6 pass ways pass way A is the connection with the Laser Deposition

Equipment pass way B is the connection with the Turbo Pump and pass way C is for the connection with

the Deposition Source

A

C

B

79

Pass way C is for the deposition source as mentioned above This is a system where a thermal

resistance is heated by passing a high current through it which heats up a filament boat (made of tungsten)

where the material to be evaporated is place We control the temperature as such that the material will

evaporate and the heat will not cause the filament boat to crack

Because P = Isup2 R (where P is power I is current and R is resistance) to avoid the current to flow

where it is not desired we decided that the material for the Thermocouple shown in figure 4-3 should be

Copper ᴓ 63 mm We choose it that way because Copper has very good heat dissipation characteristics

and the resistance value is low It can reduce the value of the current enough to make the thermocouple to

create heat

Fig 4-3 Thermocouple

To the thermocouple we attach the tungsten filament boat We need to take notice of materials to be

used in this design because when using high current the tungsten filament boar will heat up and so the

material must be able to keep up with the heating potential of tungsten and has a low coefficient of heat

dissipation to avoid the tungsten to fail when heating up and therefore not evaporating Considering all

this we decide to use Stainless Steel

Because this clamp will be assembled inside the chamber after many revisions it was determined it

will have the shape shown in figure 4-4

Fig 4-4 Filament Boat Clamp Design

80

For the tungsten filament boat we bought the product from a distributor The dimensions are

Length 100 mm

Width 10 mm

Height 1 mm

Our thermocouple is 15 in but the pass way C is 4 in so we need to attach a Flange that connects

15in to 4in Because these specifications are quite difficult to achieve by Milling we had to use

electrical wire cutting

For the laser clamping system where the laser that is going to be AR coated will be placed will be

connected to pass way A the assembly is shown in figure 4-5 below

Fig 4-5 Cover Assembly

For this design we used an O-ring instead of a gasket so as to save time The design of the assembly

where the laser will be placed is shown in figure 4-6

Fig 4-6 Upper Cover Inner Assembly

D

E

F

81

Point D is the plate in the assembly where the laser diode will be fixed Because of the easy

processing we decide to use Aluminum and it is screwed to the top cover Point E is the connection for

the Quartz crystal resonator and it is designed in the same as point F in this way the results of the quartz

microbalance system will be more accurate in real time Point F is the final resting place for the laser

diode We use a Thor Labs Base with dimensions of ᴓ 9mm and ᴓ 56mm for two different size laser

diodes It just needs to be plugged in for easy installation

From figure 4-6 we know that the system needs signal system connections and because of the

change in temperature inside the chamber this could affect the functioning of the quartz microbalance so

we also need to install water tubes for cooling This is shown in figure 4-7 below

Fig 4-7 Diagram of Upper Cover Connections

In figure 4-8 we show the Feed through connections and their functions

Fig 4-8 Feed through Diagram

82

1 SQM-160 wire 5 Laser Connection 1 (Vin)

2 SQM-160 (G) 6 Laser Connection 2 (G)

3 K-Type-1 7 Laser Connection 3 (PD)

4 K-Type-2 8 Not In Use

The fully assembled chamber is shown in figure 4-9

Fig 4-9 Fully Assembled Chamber

422 Quartz Crystal Microbalance

For measuring the deposition on our target for coating we used the Inficon SQM-160 RateThickness

Monitor It is an easy to use instrument for measuring many types of thin-film coatings as shown in

figure 4-10

(a) Front Panel (b) Back Panel

Fig 4-10 Inficon SQM-160

83

Table 4-1 shows the technical specifications for this equipment

Number of sensors 2 Standard 4 additional optional

Sensor Frequency Range 40 MHz ~ 60 MHz

Reference Frequency Accuracy 002

Thickness Display Resolution 1 Aring

Thickness Resolution 015 Aring (Std) 0037 Aring (Hi Res)

Density of Stored Films 05-9999 gmcc

Tooling 10-399

Z-Factor 010-1000

Final Thickness 0000-9999k Aring

Measurement Period 15 to 2 sec

Simulation Mode Yes

Frequency Mode Yes

Rate Resolution 011 Arings

Dual Crystal Yes

Etch Mode Yes

Crystal Tooling 10-399

Crystal Fail Min Max 40 to 60 MHz 41 to 61 MHz

Power 100-120 200-240~plusmn10 nominal 20W

Operation Environment 0degC ~ 50degC

0 ~ 80 RH non-condensing

0 ~ 2000 meters

Class 1 Equipment

Pollution Degree 2

Rack Dimensions 885mm x 2127mm x 1969mm

Weight 27 kg

Table 4-1 Inficon SQM-160 RateThickness Monitor Specs

84

To the SQM-160 we need to connect an Oscillator We use the Sigma Instruments Remote Oscillator

Ser No 2 268 as shown in figure 4-11

Fig 4-11 Sigma Instruments Remote Oscillator

The connections diagram is shown in figure 4-12

Fig 4-12 SQM-160 Connections Diagram

85

423 Turbo Pump

For our experiments we used the Pfeiffer TCP 015 Electronic Drive Unit shown below in figure 4-13

Table 4-2 shows the technical specifications for this equipment

(a) Front Panel (b) Back Panel

Fig 4-13 Pfeiffer TCP 015 Electronic Drive

Connection Voltage (100V) 90-112

Mains Frequency 5060 Hz

Start-up Current 22 A

Nominal Frequency 1500 Hz

Rotation Speed 10V = 1500Hz plusmn2

Analog Output Current 10 V = 25 A plusmn 5

Rotation Speed Switchpoint 750 Hz

Works Setting 8 min

Permissible Ambient Temperature 0degC ~ 40degC

Dimensions Front Panel 1285mm x 1063mm

Insertion Length 227mm

Weight 27 Kg

Table 4-2 Pfeiffer TCP 015 Electronic Drive Specs

86

The connections diagram is shown in figure 4-14

Fig 4-14Connections Diagram for Pfeiffer TCP 015

To measure the pressure inside the chamber we use the Granville Phillips 375 Convectron Vacuum

Pressure Controller shown in figure 4-15

(a) Front Panel (b) Back Panel

Fig 4-15 Granville Phillips 375 Convectron

87

Its dimensions are shown in figure 4-16

Fig 4-16 Dimensions of Convectron

Table 4-3 shows the technical specifications for this equipment

Table 4-3 Granville Phillips 375 Convectron Vacuum Pressure Controller Specs

88

424 Multimeter

For our experiment we used the Keithley 2000 Digital Multimeter as shown in figure 4-17

(a) Front Panel (b) Back Panel

Fig 4-17 Keithley Model 2000 6-12-Digit Digital Multimeter

Its technical specifications are shown in table 4-4

Table 4-4 Keithley Model 2000 6-12-Digit Digital Multimeter Specs

89

43 Experiment Procedure

1 Connecting together the equipment and the chamber

(1) We first connect the resonator to the thickness monitor and connect the other side to the

chamber

(2) We now connect the flexible tubes to the turbo pump on one side and to the chamber on the

other

(3) We need to check that tubes are tightly connected to avoid any leaks in the vacuum pumping

process which will not allow us to get to our goal of Torr As shown in figure 4-18

(4) Connect the convectron to the system as shown in figure 4-19

Fig 4-18 checking for leaks using alcohol

Fig 4-19 Convectron attached to System

90

(5) Attach the clamps of the Multimeter to the bottom of the chamber as shown in figure 4-20

(6) Place the Quartz crystal in place

(7) Close tight vacuum chamber

(8) Connect all electrical appliances to power source

Fig 4-20 Multimeter Connections

2 Starting up the System

(1) We turn on all the devices as such Check all systems are ready to function Reset all values

that might be left over from previous tests

(2) Start the thickness monitor and set all values for this experiment In our case we got to testing

the system but not actual coating So we used the simulation mode of the thickness monitor as

shown in figure 4-21

Fig 4-21 Simulation Mode

91

(3) Start the turbo pump Make sure the lid on the vacuum chamber is tightly closed

(4) Start convectron and record initial pressure

(5) Start Multimeter and record initial current

3 Coating Process

(1) If we have the deposition material inside the filament boat the power source for the high

current must be started as well

(2) Record all initial values for thickness current pressure

(3) For an ideal experiment we need a thickness of around 101 nm a pressure of Torr and

a current of 300 A

44 Results

From previous experiments we have shown that we can turn a LED into a laser by means of AR

Coating In figure 4-22 shown below we can compare the actual results of a Diode before and after AR

coating From the blue line we can see that when the diode is at a current of 15mA its light will change

from LED to laser and if we look at the red line its critical current is around 30 to 35 mA

Fig 4-22 AR Coating Comparison for Laser Diodes

This means that the light emitted is not as strong as if the diode had been coated because inside the

chamber there must be some excitation first so the reflectivity of both sides inside the diode must be high

So because of the coating in one of the sides we have opened a door and let the light come out so the

critical current is risen as such and will be higher value than that of before the coating

92

In the following figures we can see the difference between before and after coating in a material The

thickness is around 1016 nm for this material

Fig 4-23 Before Coating

Fig 4-24 After Coating

93

Chapter 5 CONCLUSIONS AND RECOMMENDATIONS

51 Conclusions

For the first part of this independent study taking into consideration the data that came out of our

research and that sent by the provider we can say

1 SUM 23 after heat treatment will unexpectedly develop cracking in the middle of the tensile

testing process and suddenly break

2 Itrsquos possible that in the process of heat treatment to the SUM 23 material the treatment was not

uniform and this will create a pre-loaded moment force on one side that pushes on the other side

of the specimen resulting in material deformation

3 In the process of attaching the strain gauges to the materials it is very easy to make errors due to

poor adhesion or sudden removal in the tensile testing process

For our second part of the independent study the following can be made

1 At the beginning of this independent study we had no idea what Bose-Einstein Condensate was

or what was its purpose After much literature we finally comprehended the basic principles to

put into practice for our research

2 Our systemrsquos basic working principles and equipmentrsquos complexity are a little difficult to grasp

but hopefully we were able to understand enough of it

3 Theoretically from relation between the power and current we can know the advantages and

disadvantages of AR Coating

4 We were able to assemble the system and run test on its functions Even though we were able to

do this there is still much more work left to do with this system

52 Recommendations

For the Tensile Testing the following can be said

1 Ask the provider to check on the process of heat treatment on the SUM 23 material and give

them the information we have gathered through our test so they can correct for the mechanical

properties found if any change is needed

2 To avoid the problem of the inaccuracy of the poor adhesion of strain gauges we can attach

multiple strain gauges to the same one specimen so as to correlate data and improve our results

For the AR Coating the following can be said

1 We need to make sure that there are no physical defects on the main body of the chamber so as to

achieve maximum efficiency in the vacuum process If there was then the vacuum will arrive to

certain point and then start to decrease

2 It would be preferable to add some sort of visual aid that will allow the user to check the inside of

the chamber without actually opening it This will help us determine at what times we should

manipulate the current to better evaporate the substrate

94

REFERENCES

[1] A L Window Strain Gauge Technology Elsevier Applied Science London and New York 2nd

Edition 1992

[2] CC Perry and HR Lissner Strain Gauge Primer McGraw-Hill Book Co Inc New York 1955

[3] James W Dally William F Riley McGraw-Hill 1978

[4] University of Colorado Boulder BEC - What is it and where did the idea come from

httpwwwcoloradoeduphysics2000becwhat_is_ithtml

[5] Ultraslow Light amp Bose-Einstein Condensates Two-way Control with Coherent Light amp Atom

Fields Harvard Hau Lab Dr Lene Vestergaard Hau Optics amp Photonics News 16 1995

[6] The Art of Taming Light Ultra-slow and Stopped Light Harvard Hau Lab Dr Lene

Vestergaard Hau Europhysics News 2004

[7] Nonlinear Optics Shocking Superfluids Harvard Hau Lab Dr Lene Vestergaard Hau Nature

Physics 2007

[8] Model P3 Strain Indicator and Recorder Instruction Manual Vishay Micro-Measurements 2005

[9] Granville-Phillips Series 375 Convectron Vacuum Gauge Controller Instruction Manual Brooks

Automation 2008

[10] Effect of Film Thickness on the Validity of the Sauerbrey Equation for Hydrated Polyelectrolyte

Films Vogt Lin Wu White 2004

[11] Quartz Crystal Microbalance Study of DNA Immobilization and Hybridization for DNA Sensor

Development Chang Zhao 2008

[12] Installation of Strain Gages with SR-4 PrecoatAdhesive Vishay Micro-Measurements 2005

[13] Strain Gauge Measurement ndash A Tutorial National Instruments 1998

[14] Correlation between Vickers Hardness Number and Yield Stress of Cold-Formed Products

Yavuz Tekkaya

[15] httpsenwikipediaorg

Page 79: PC Hinge Materials Testing and AR Laser Diode Coating

79

Pass way C is for the deposition source as mentioned above This is a system where a thermal

resistance is heated by passing a high current through it which heats up a filament boat (made of tungsten)

where the material to be evaporated is place We control the temperature as such that the material will

evaporate and the heat will not cause the filament boat to crack

Because P = Isup2 R (where P is power I is current and R is resistance) to avoid the current to flow

where it is not desired we decided that the material for the Thermocouple shown in figure 4-3 should be

Copper ᴓ 63 mm We choose it that way because Copper has very good heat dissipation characteristics

and the resistance value is low It can reduce the value of the current enough to make the thermocouple to

create heat

Fig 4-3 Thermocouple

To the thermocouple we attach the tungsten filament boat We need to take notice of materials to be

used in this design because when using high current the tungsten filament boar will heat up and so the

material must be able to keep up with the heating potential of tungsten and has a low coefficient of heat

dissipation to avoid the tungsten to fail when heating up and therefore not evaporating Considering all

this we decide to use Stainless Steel

Because this clamp will be assembled inside the chamber after many revisions it was determined it

will have the shape shown in figure 4-4

Fig 4-4 Filament Boat Clamp Design

80

For the tungsten filament boat we bought the product from a distributor The dimensions are

Length 100 mm

Width 10 mm

Height 1 mm

Our thermocouple is 15 in but the pass way C is 4 in so we need to attach a Flange that connects

15in to 4in Because these specifications are quite difficult to achieve by Milling we had to use

electrical wire cutting

For the laser clamping system where the laser that is going to be AR coated will be placed will be

connected to pass way A the assembly is shown in figure 4-5 below

Fig 4-5 Cover Assembly

For this design we used an O-ring instead of a gasket so as to save time The design of the assembly

where the laser will be placed is shown in figure 4-6

Fig 4-6 Upper Cover Inner Assembly

D

E

F

81

Point D is the plate in the assembly where the laser diode will be fixed Because of the easy

processing we decide to use Aluminum and it is screwed to the top cover Point E is the connection for

the Quartz crystal resonator and it is designed in the same as point F in this way the results of the quartz

microbalance system will be more accurate in real time Point F is the final resting place for the laser

diode We use a Thor Labs Base with dimensions of ᴓ 9mm and ᴓ 56mm for two different size laser

diodes It just needs to be plugged in for easy installation

From figure 4-6 we know that the system needs signal system connections and because of the

change in temperature inside the chamber this could affect the functioning of the quartz microbalance so

we also need to install water tubes for cooling This is shown in figure 4-7 below

Fig 4-7 Diagram of Upper Cover Connections

In figure 4-8 we show the Feed through connections and their functions

Fig 4-8 Feed through Diagram

82

1 SQM-160 wire 5 Laser Connection 1 (Vin)

2 SQM-160 (G) 6 Laser Connection 2 (G)

3 K-Type-1 7 Laser Connection 3 (PD)

4 K-Type-2 8 Not In Use

The fully assembled chamber is shown in figure 4-9

Fig 4-9 Fully Assembled Chamber

422 Quartz Crystal Microbalance

For measuring the deposition on our target for coating we used the Inficon SQM-160 RateThickness

Monitor It is an easy to use instrument for measuring many types of thin-film coatings as shown in

figure 4-10

(a) Front Panel (b) Back Panel

Fig 4-10 Inficon SQM-160

83

Table 4-1 shows the technical specifications for this equipment

Number of sensors 2 Standard 4 additional optional

Sensor Frequency Range 40 MHz ~ 60 MHz

Reference Frequency Accuracy 002

Thickness Display Resolution 1 Aring

Thickness Resolution 015 Aring (Std) 0037 Aring (Hi Res)

Density of Stored Films 05-9999 gmcc

Tooling 10-399

Z-Factor 010-1000

Final Thickness 0000-9999k Aring

Measurement Period 15 to 2 sec

Simulation Mode Yes

Frequency Mode Yes

Rate Resolution 011 Arings

Dual Crystal Yes

Etch Mode Yes

Crystal Tooling 10-399

Crystal Fail Min Max 40 to 60 MHz 41 to 61 MHz

Power 100-120 200-240~plusmn10 nominal 20W

Operation Environment 0degC ~ 50degC

0 ~ 80 RH non-condensing

0 ~ 2000 meters

Class 1 Equipment

Pollution Degree 2

Rack Dimensions 885mm x 2127mm x 1969mm

Weight 27 kg

Table 4-1 Inficon SQM-160 RateThickness Monitor Specs

84

To the SQM-160 we need to connect an Oscillator We use the Sigma Instruments Remote Oscillator

Ser No 2 268 as shown in figure 4-11

Fig 4-11 Sigma Instruments Remote Oscillator

The connections diagram is shown in figure 4-12

Fig 4-12 SQM-160 Connections Diagram

85

423 Turbo Pump

For our experiments we used the Pfeiffer TCP 015 Electronic Drive Unit shown below in figure 4-13

Table 4-2 shows the technical specifications for this equipment

(a) Front Panel (b) Back Panel

Fig 4-13 Pfeiffer TCP 015 Electronic Drive

Connection Voltage (100V) 90-112

Mains Frequency 5060 Hz

Start-up Current 22 A

Nominal Frequency 1500 Hz

Rotation Speed 10V = 1500Hz plusmn2

Analog Output Current 10 V = 25 A plusmn 5

Rotation Speed Switchpoint 750 Hz

Works Setting 8 min

Permissible Ambient Temperature 0degC ~ 40degC

Dimensions Front Panel 1285mm x 1063mm

Insertion Length 227mm

Weight 27 Kg

Table 4-2 Pfeiffer TCP 015 Electronic Drive Specs

86

The connections diagram is shown in figure 4-14

Fig 4-14Connections Diagram for Pfeiffer TCP 015

To measure the pressure inside the chamber we use the Granville Phillips 375 Convectron Vacuum

Pressure Controller shown in figure 4-15

(a) Front Panel (b) Back Panel

Fig 4-15 Granville Phillips 375 Convectron

87

Its dimensions are shown in figure 4-16

Fig 4-16 Dimensions of Convectron

Table 4-3 shows the technical specifications for this equipment

Table 4-3 Granville Phillips 375 Convectron Vacuum Pressure Controller Specs

88

424 Multimeter

For our experiment we used the Keithley 2000 Digital Multimeter as shown in figure 4-17

(a) Front Panel (b) Back Panel

Fig 4-17 Keithley Model 2000 6-12-Digit Digital Multimeter

Its technical specifications are shown in table 4-4

Table 4-4 Keithley Model 2000 6-12-Digit Digital Multimeter Specs

89

43 Experiment Procedure

1 Connecting together the equipment and the chamber

(1) We first connect the resonator to the thickness monitor and connect the other side to the

chamber

(2) We now connect the flexible tubes to the turbo pump on one side and to the chamber on the

other

(3) We need to check that tubes are tightly connected to avoid any leaks in the vacuum pumping

process which will not allow us to get to our goal of Torr As shown in figure 4-18

(4) Connect the convectron to the system as shown in figure 4-19

Fig 4-18 checking for leaks using alcohol

Fig 4-19 Convectron attached to System

90

(5) Attach the clamps of the Multimeter to the bottom of the chamber as shown in figure 4-20

(6) Place the Quartz crystal in place

(7) Close tight vacuum chamber

(8) Connect all electrical appliances to power source

Fig 4-20 Multimeter Connections

2 Starting up the System

(1) We turn on all the devices as such Check all systems are ready to function Reset all values

that might be left over from previous tests

(2) Start the thickness monitor and set all values for this experiment In our case we got to testing

the system but not actual coating So we used the simulation mode of the thickness monitor as

shown in figure 4-21

Fig 4-21 Simulation Mode

91

(3) Start the turbo pump Make sure the lid on the vacuum chamber is tightly closed

(4) Start convectron and record initial pressure

(5) Start Multimeter and record initial current

3 Coating Process

(1) If we have the deposition material inside the filament boat the power source for the high

current must be started as well

(2) Record all initial values for thickness current pressure

(3) For an ideal experiment we need a thickness of around 101 nm a pressure of Torr and

a current of 300 A

44 Results

From previous experiments we have shown that we can turn a LED into a laser by means of AR

Coating In figure 4-22 shown below we can compare the actual results of a Diode before and after AR

coating From the blue line we can see that when the diode is at a current of 15mA its light will change

from LED to laser and if we look at the red line its critical current is around 30 to 35 mA

Fig 4-22 AR Coating Comparison for Laser Diodes

This means that the light emitted is not as strong as if the diode had been coated because inside the

chamber there must be some excitation first so the reflectivity of both sides inside the diode must be high

So because of the coating in one of the sides we have opened a door and let the light come out so the

critical current is risen as such and will be higher value than that of before the coating

92

In the following figures we can see the difference between before and after coating in a material The

thickness is around 1016 nm for this material

Fig 4-23 Before Coating

Fig 4-24 After Coating

93

Chapter 5 CONCLUSIONS AND RECOMMENDATIONS

51 Conclusions

For the first part of this independent study taking into consideration the data that came out of our

research and that sent by the provider we can say

1 SUM 23 after heat treatment will unexpectedly develop cracking in the middle of the tensile

testing process and suddenly break

2 Itrsquos possible that in the process of heat treatment to the SUM 23 material the treatment was not

uniform and this will create a pre-loaded moment force on one side that pushes on the other side

of the specimen resulting in material deformation

3 In the process of attaching the strain gauges to the materials it is very easy to make errors due to

poor adhesion or sudden removal in the tensile testing process

For our second part of the independent study the following can be made

1 At the beginning of this independent study we had no idea what Bose-Einstein Condensate was

or what was its purpose After much literature we finally comprehended the basic principles to

put into practice for our research

2 Our systemrsquos basic working principles and equipmentrsquos complexity are a little difficult to grasp

but hopefully we were able to understand enough of it

3 Theoretically from relation between the power and current we can know the advantages and

disadvantages of AR Coating

4 We were able to assemble the system and run test on its functions Even though we were able to

do this there is still much more work left to do with this system

52 Recommendations

For the Tensile Testing the following can be said

1 Ask the provider to check on the process of heat treatment on the SUM 23 material and give

them the information we have gathered through our test so they can correct for the mechanical

properties found if any change is needed

2 To avoid the problem of the inaccuracy of the poor adhesion of strain gauges we can attach

multiple strain gauges to the same one specimen so as to correlate data and improve our results

For the AR Coating the following can be said

1 We need to make sure that there are no physical defects on the main body of the chamber so as to

achieve maximum efficiency in the vacuum process If there was then the vacuum will arrive to

certain point and then start to decrease

2 It would be preferable to add some sort of visual aid that will allow the user to check the inside of

the chamber without actually opening it This will help us determine at what times we should

manipulate the current to better evaporate the substrate

94

REFERENCES

[1] A L Window Strain Gauge Technology Elsevier Applied Science London and New York 2nd

Edition 1992

[2] CC Perry and HR Lissner Strain Gauge Primer McGraw-Hill Book Co Inc New York 1955

[3] James W Dally William F Riley McGraw-Hill 1978

[4] University of Colorado Boulder BEC - What is it and where did the idea come from

httpwwwcoloradoeduphysics2000becwhat_is_ithtml

[5] Ultraslow Light amp Bose-Einstein Condensates Two-way Control with Coherent Light amp Atom

Fields Harvard Hau Lab Dr Lene Vestergaard Hau Optics amp Photonics News 16 1995

[6] The Art of Taming Light Ultra-slow and Stopped Light Harvard Hau Lab Dr Lene

Vestergaard Hau Europhysics News 2004

[7] Nonlinear Optics Shocking Superfluids Harvard Hau Lab Dr Lene Vestergaard Hau Nature

Physics 2007

[8] Model P3 Strain Indicator and Recorder Instruction Manual Vishay Micro-Measurements 2005

[9] Granville-Phillips Series 375 Convectron Vacuum Gauge Controller Instruction Manual Brooks

Automation 2008

[10] Effect of Film Thickness on the Validity of the Sauerbrey Equation for Hydrated Polyelectrolyte

Films Vogt Lin Wu White 2004

[11] Quartz Crystal Microbalance Study of DNA Immobilization and Hybridization for DNA Sensor

Development Chang Zhao 2008

[12] Installation of Strain Gages with SR-4 PrecoatAdhesive Vishay Micro-Measurements 2005

[13] Strain Gauge Measurement ndash A Tutorial National Instruments 1998

[14] Correlation between Vickers Hardness Number and Yield Stress of Cold-Formed Products

Yavuz Tekkaya

[15] httpsenwikipediaorg

Page 80: PC Hinge Materials Testing and AR Laser Diode Coating

80

For the tungsten filament boat we bought the product from a distributor The dimensions are

Length 100 mm

Width 10 mm

Height 1 mm

Our thermocouple is 15 in but the pass way C is 4 in so we need to attach a Flange that connects

15in to 4in Because these specifications are quite difficult to achieve by Milling we had to use

electrical wire cutting

For the laser clamping system where the laser that is going to be AR coated will be placed will be

connected to pass way A the assembly is shown in figure 4-5 below

Fig 4-5 Cover Assembly

For this design we used an O-ring instead of a gasket so as to save time The design of the assembly

where the laser will be placed is shown in figure 4-6

Fig 4-6 Upper Cover Inner Assembly

D

E

F

81

Point D is the plate in the assembly where the laser diode will be fixed Because of the easy

processing we decide to use Aluminum and it is screwed to the top cover Point E is the connection for

the Quartz crystal resonator and it is designed in the same as point F in this way the results of the quartz

microbalance system will be more accurate in real time Point F is the final resting place for the laser

diode We use a Thor Labs Base with dimensions of ᴓ 9mm and ᴓ 56mm for two different size laser

diodes It just needs to be plugged in for easy installation

From figure 4-6 we know that the system needs signal system connections and because of the

change in temperature inside the chamber this could affect the functioning of the quartz microbalance so

we also need to install water tubes for cooling This is shown in figure 4-7 below

Fig 4-7 Diagram of Upper Cover Connections

In figure 4-8 we show the Feed through connections and their functions

Fig 4-8 Feed through Diagram

82

1 SQM-160 wire 5 Laser Connection 1 (Vin)

2 SQM-160 (G) 6 Laser Connection 2 (G)

3 K-Type-1 7 Laser Connection 3 (PD)

4 K-Type-2 8 Not In Use

The fully assembled chamber is shown in figure 4-9

Fig 4-9 Fully Assembled Chamber

422 Quartz Crystal Microbalance

For measuring the deposition on our target for coating we used the Inficon SQM-160 RateThickness

Monitor It is an easy to use instrument for measuring many types of thin-film coatings as shown in

figure 4-10

(a) Front Panel (b) Back Panel

Fig 4-10 Inficon SQM-160

83

Table 4-1 shows the technical specifications for this equipment

Number of sensors 2 Standard 4 additional optional

Sensor Frequency Range 40 MHz ~ 60 MHz

Reference Frequency Accuracy 002

Thickness Display Resolution 1 Aring

Thickness Resolution 015 Aring (Std) 0037 Aring (Hi Res)

Density of Stored Films 05-9999 gmcc

Tooling 10-399

Z-Factor 010-1000

Final Thickness 0000-9999k Aring

Measurement Period 15 to 2 sec

Simulation Mode Yes

Frequency Mode Yes

Rate Resolution 011 Arings

Dual Crystal Yes

Etch Mode Yes

Crystal Tooling 10-399

Crystal Fail Min Max 40 to 60 MHz 41 to 61 MHz

Power 100-120 200-240~plusmn10 nominal 20W

Operation Environment 0degC ~ 50degC

0 ~ 80 RH non-condensing

0 ~ 2000 meters

Class 1 Equipment

Pollution Degree 2

Rack Dimensions 885mm x 2127mm x 1969mm

Weight 27 kg

Table 4-1 Inficon SQM-160 RateThickness Monitor Specs

84

To the SQM-160 we need to connect an Oscillator We use the Sigma Instruments Remote Oscillator

Ser No 2 268 as shown in figure 4-11

Fig 4-11 Sigma Instruments Remote Oscillator

The connections diagram is shown in figure 4-12

Fig 4-12 SQM-160 Connections Diagram

85

423 Turbo Pump

For our experiments we used the Pfeiffer TCP 015 Electronic Drive Unit shown below in figure 4-13

Table 4-2 shows the technical specifications for this equipment

(a) Front Panel (b) Back Panel

Fig 4-13 Pfeiffer TCP 015 Electronic Drive

Connection Voltage (100V) 90-112

Mains Frequency 5060 Hz

Start-up Current 22 A

Nominal Frequency 1500 Hz

Rotation Speed 10V = 1500Hz plusmn2

Analog Output Current 10 V = 25 A plusmn 5

Rotation Speed Switchpoint 750 Hz

Works Setting 8 min

Permissible Ambient Temperature 0degC ~ 40degC

Dimensions Front Panel 1285mm x 1063mm

Insertion Length 227mm

Weight 27 Kg

Table 4-2 Pfeiffer TCP 015 Electronic Drive Specs

86

The connections diagram is shown in figure 4-14

Fig 4-14Connections Diagram for Pfeiffer TCP 015

To measure the pressure inside the chamber we use the Granville Phillips 375 Convectron Vacuum

Pressure Controller shown in figure 4-15

(a) Front Panel (b) Back Panel

Fig 4-15 Granville Phillips 375 Convectron

87

Its dimensions are shown in figure 4-16

Fig 4-16 Dimensions of Convectron

Table 4-3 shows the technical specifications for this equipment

Table 4-3 Granville Phillips 375 Convectron Vacuum Pressure Controller Specs

88

424 Multimeter

For our experiment we used the Keithley 2000 Digital Multimeter as shown in figure 4-17

(a) Front Panel (b) Back Panel

Fig 4-17 Keithley Model 2000 6-12-Digit Digital Multimeter

Its technical specifications are shown in table 4-4

Table 4-4 Keithley Model 2000 6-12-Digit Digital Multimeter Specs

89

43 Experiment Procedure

1 Connecting together the equipment and the chamber

(1) We first connect the resonator to the thickness monitor and connect the other side to the

chamber

(2) We now connect the flexible tubes to the turbo pump on one side and to the chamber on the

other

(3) We need to check that tubes are tightly connected to avoid any leaks in the vacuum pumping

process which will not allow us to get to our goal of Torr As shown in figure 4-18

(4) Connect the convectron to the system as shown in figure 4-19

Fig 4-18 checking for leaks using alcohol

Fig 4-19 Convectron attached to System

90

(5) Attach the clamps of the Multimeter to the bottom of the chamber as shown in figure 4-20

(6) Place the Quartz crystal in place

(7) Close tight vacuum chamber

(8) Connect all electrical appliances to power source

Fig 4-20 Multimeter Connections

2 Starting up the System

(1) We turn on all the devices as such Check all systems are ready to function Reset all values

that might be left over from previous tests

(2) Start the thickness monitor and set all values for this experiment In our case we got to testing

the system but not actual coating So we used the simulation mode of the thickness monitor as

shown in figure 4-21

Fig 4-21 Simulation Mode

91

(3) Start the turbo pump Make sure the lid on the vacuum chamber is tightly closed

(4) Start convectron and record initial pressure

(5) Start Multimeter and record initial current

3 Coating Process

(1) If we have the deposition material inside the filament boat the power source for the high

current must be started as well

(2) Record all initial values for thickness current pressure

(3) For an ideal experiment we need a thickness of around 101 nm a pressure of Torr and

a current of 300 A

44 Results

From previous experiments we have shown that we can turn a LED into a laser by means of AR

Coating In figure 4-22 shown below we can compare the actual results of a Diode before and after AR

coating From the blue line we can see that when the diode is at a current of 15mA its light will change

from LED to laser and if we look at the red line its critical current is around 30 to 35 mA

Fig 4-22 AR Coating Comparison for Laser Diodes

This means that the light emitted is not as strong as if the diode had been coated because inside the

chamber there must be some excitation first so the reflectivity of both sides inside the diode must be high

So because of the coating in one of the sides we have opened a door and let the light come out so the

critical current is risen as such and will be higher value than that of before the coating

92

In the following figures we can see the difference between before and after coating in a material The

thickness is around 1016 nm for this material

Fig 4-23 Before Coating

Fig 4-24 After Coating

93

Chapter 5 CONCLUSIONS AND RECOMMENDATIONS

51 Conclusions

For the first part of this independent study taking into consideration the data that came out of our

research and that sent by the provider we can say

1 SUM 23 after heat treatment will unexpectedly develop cracking in the middle of the tensile

testing process and suddenly break

2 Itrsquos possible that in the process of heat treatment to the SUM 23 material the treatment was not

uniform and this will create a pre-loaded moment force on one side that pushes on the other side

of the specimen resulting in material deformation

3 In the process of attaching the strain gauges to the materials it is very easy to make errors due to

poor adhesion or sudden removal in the tensile testing process

For our second part of the independent study the following can be made

1 At the beginning of this independent study we had no idea what Bose-Einstein Condensate was

or what was its purpose After much literature we finally comprehended the basic principles to

put into practice for our research

2 Our systemrsquos basic working principles and equipmentrsquos complexity are a little difficult to grasp

but hopefully we were able to understand enough of it

3 Theoretically from relation between the power and current we can know the advantages and

disadvantages of AR Coating

4 We were able to assemble the system and run test on its functions Even though we were able to

do this there is still much more work left to do with this system

52 Recommendations

For the Tensile Testing the following can be said

1 Ask the provider to check on the process of heat treatment on the SUM 23 material and give

them the information we have gathered through our test so they can correct for the mechanical

properties found if any change is needed

2 To avoid the problem of the inaccuracy of the poor adhesion of strain gauges we can attach

multiple strain gauges to the same one specimen so as to correlate data and improve our results

For the AR Coating the following can be said

1 We need to make sure that there are no physical defects on the main body of the chamber so as to

achieve maximum efficiency in the vacuum process If there was then the vacuum will arrive to

certain point and then start to decrease

2 It would be preferable to add some sort of visual aid that will allow the user to check the inside of

the chamber without actually opening it This will help us determine at what times we should

manipulate the current to better evaporate the substrate

94

REFERENCES

[1] A L Window Strain Gauge Technology Elsevier Applied Science London and New York 2nd

Edition 1992

[2] CC Perry and HR Lissner Strain Gauge Primer McGraw-Hill Book Co Inc New York 1955

[3] James W Dally William F Riley McGraw-Hill 1978

[4] University of Colorado Boulder BEC - What is it and where did the idea come from

httpwwwcoloradoeduphysics2000becwhat_is_ithtml

[5] Ultraslow Light amp Bose-Einstein Condensates Two-way Control with Coherent Light amp Atom

Fields Harvard Hau Lab Dr Lene Vestergaard Hau Optics amp Photonics News 16 1995

[6] The Art of Taming Light Ultra-slow and Stopped Light Harvard Hau Lab Dr Lene

Vestergaard Hau Europhysics News 2004

[7] Nonlinear Optics Shocking Superfluids Harvard Hau Lab Dr Lene Vestergaard Hau Nature

Physics 2007

[8] Model P3 Strain Indicator and Recorder Instruction Manual Vishay Micro-Measurements 2005

[9] Granville-Phillips Series 375 Convectron Vacuum Gauge Controller Instruction Manual Brooks

Automation 2008

[10] Effect of Film Thickness on the Validity of the Sauerbrey Equation for Hydrated Polyelectrolyte

Films Vogt Lin Wu White 2004

[11] Quartz Crystal Microbalance Study of DNA Immobilization and Hybridization for DNA Sensor

Development Chang Zhao 2008

[12] Installation of Strain Gages with SR-4 PrecoatAdhesive Vishay Micro-Measurements 2005

[13] Strain Gauge Measurement ndash A Tutorial National Instruments 1998

[14] Correlation between Vickers Hardness Number and Yield Stress of Cold-Formed Products

Yavuz Tekkaya

[15] httpsenwikipediaorg

Page 81: PC Hinge Materials Testing and AR Laser Diode Coating

81

Point D is the plate in the assembly where the laser diode will be fixed Because of the easy

processing we decide to use Aluminum and it is screwed to the top cover Point E is the connection for

the Quartz crystal resonator and it is designed in the same as point F in this way the results of the quartz

microbalance system will be more accurate in real time Point F is the final resting place for the laser

diode We use a Thor Labs Base with dimensions of ᴓ 9mm and ᴓ 56mm for two different size laser

diodes It just needs to be plugged in for easy installation

From figure 4-6 we know that the system needs signal system connections and because of the

change in temperature inside the chamber this could affect the functioning of the quartz microbalance so

we also need to install water tubes for cooling This is shown in figure 4-7 below

Fig 4-7 Diagram of Upper Cover Connections

In figure 4-8 we show the Feed through connections and their functions

Fig 4-8 Feed through Diagram

82

1 SQM-160 wire 5 Laser Connection 1 (Vin)

2 SQM-160 (G) 6 Laser Connection 2 (G)

3 K-Type-1 7 Laser Connection 3 (PD)

4 K-Type-2 8 Not In Use

The fully assembled chamber is shown in figure 4-9

Fig 4-9 Fully Assembled Chamber

422 Quartz Crystal Microbalance

For measuring the deposition on our target for coating we used the Inficon SQM-160 RateThickness

Monitor It is an easy to use instrument for measuring many types of thin-film coatings as shown in

figure 4-10

(a) Front Panel (b) Back Panel

Fig 4-10 Inficon SQM-160

83

Table 4-1 shows the technical specifications for this equipment

Number of sensors 2 Standard 4 additional optional

Sensor Frequency Range 40 MHz ~ 60 MHz

Reference Frequency Accuracy 002

Thickness Display Resolution 1 Aring

Thickness Resolution 015 Aring (Std) 0037 Aring (Hi Res)

Density of Stored Films 05-9999 gmcc

Tooling 10-399

Z-Factor 010-1000

Final Thickness 0000-9999k Aring

Measurement Period 15 to 2 sec

Simulation Mode Yes

Frequency Mode Yes

Rate Resolution 011 Arings

Dual Crystal Yes

Etch Mode Yes

Crystal Tooling 10-399

Crystal Fail Min Max 40 to 60 MHz 41 to 61 MHz

Power 100-120 200-240~plusmn10 nominal 20W

Operation Environment 0degC ~ 50degC

0 ~ 80 RH non-condensing

0 ~ 2000 meters

Class 1 Equipment

Pollution Degree 2

Rack Dimensions 885mm x 2127mm x 1969mm

Weight 27 kg

Table 4-1 Inficon SQM-160 RateThickness Monitor Specs

84

To the SQM-160 we need to connect an Oscillator We use the Sigma Instruments Remote Oscillator

Ser No 2 268 as shown in figure 4-11

Fig 4-11 Sigma Instruments Remote Oscillator

The connections diagram is shown in figure 4-12

Fig 4-12 SQM-160 Connections Diagram

85

423 Turbo Pump

For our experiments we used the Pfeiffer TCP 015 Electronic Drive Unit shown below in figure 4-13

Table 4-2 shows the technical specifications for this equipment

(a) Front Panel (b) Back Panel

Fig 4-13 Pfeiffer TCP 015 Electronic Drive

Connection Voltage (100V) 90-112

Mains Frequency 5060 Hz

Start-up Current 22 A

Nominal Frequency 1500 Hz

Rotation Speed 10V = 1500Hz plusmn2

Analog Output Current 10 V = 25 A plusmn 5

Rotation Speed Switchpoint 750 Hz

Works Setting 8 min

Permissible Ambient Temperature 0degC ~ 40degC

Dimensions Front Panel 1285mm x 1063mm

Insertion Length 227mm

Weight 27 Kg

Table 4-2 Pfeiffer TCP 015 Electronic Drive Specs

86

The connections diagram is shown in figure 4-14

Fig 4-14Connections Diagram for Pfeiffer TCP 015

To measure the pressure inside the chamber we use the Granville Phillips 375 Convectron Vacuum

Pressure Controller shown in figure 4-15

(a) Front Panel (b) Back Panel

Fig 4-15 Granville Phillips 375 Convectron

87

Its dimensions are shown in figure 4-16

Fig 4-16 Dimensions of Convectron

Table 4-3 shows the technical specifications for this equipment

Table 4-3 Granville Phillips 375 Convectron Vacuum Pressure Controller Specs

88

424 Multimeter

For our experiment we used the Keithley 2000 Digital Multimeter as shown in figure 4-17

(a) Front Panel (b) Back Panel

Fig 4-17 Keithley Model 2000 6-12-Digit Digital Multimeter

Its technical specifications are shown in table 4-4

Table 4-4 Keithley Model 2000 6-12-Digit Digital Multimeter Specs

89

43 Experiment Procedure

1 Connecting together the equipment and the chamber

(1) We first connect the resonator to the thickness monitor and connect the other side to the

chamber

(2) We now connect the flexible tubes to the turbo pump on one side and to the chamber on the

other

(3) We need to check that tubes are tightly connected to avoid any leaks in the vacuum pumping

process which will not allow us to get to our goal of Torr As shown in figure 4-18

(4) Connect the convectron to the system as shown in figure 4-19

Fig 4-18 checking for leaks using alcohol

Fig 4-19 Convectron attached to System

90

(5) Attach the clamps of the Multimeter to the bottom of the chamber as shown in figure 4-20

(6) Place the Quartz crystal in place

(7) Close tight vacuum chamber

(8) Connect all electrical appliances to power source

Fig 4-20 Multimeter Connections

2 Starting up the System

(1) We turn on all the devices as such Check all systems are ready to function Reset all values

that might be left over from previous tests

(2) Start the thickness monitor and set all values for this experiment In our case we got to testing

the system but not actual coating So we used the simulation mode of the thickness monitor as

shown in figure 4-21

Fig 4-21 Simulation Mode

91

(3) Start the turbo pump Make sure the lid on the vacuum chamber is tightly closed

(4) Start convectron and record initial pressure

(5) Start Multimeter and record initial current

3 Coating Process

(1) If we have the deposition material inside the filament boat the power source for the high

current must be started as well

(2) Record all initial values for thickness current pressure

(3) For an ideal experiment we need a thickness of around 101 nm a pressure of Torr and

a current of 300 A

44 Results

From previous experiments we have shown that we can turn a LED into a laser by means of AR

Coating In figure 4-22 shown below we can compare the actual results of a Diode before and after AR

coating From the blue line we can see that when the diode is at a current of 15mA its light will change

from LED to laser and if we look at the red line its critical current is around 30 to 35 mA

Fig 4-22 AR Coating Comparison for Laser Diodes

This means that the light emitted is not as strong as if the diode had been coated because inside the

chamber there must be some excitation first so the reflectivity of both sides inside the diode must be high

So because of the coating in one of the sides we have opened a door and let the light come out so the

critical current is risen as such and will be higher value than that of before the coating

92

In the following figures we can see the difference between before and after coating in a material The

thickness is around 1016 nm for this material

Fig 4-23 Before Coating

Fig 4-24 After Coating

93

Chapter 5 CONCLUSIONS AND RECOMMENDATIONS

51 Conclusions

For the first part of this independent study taking into consideration the data that came out of our

research and that sent by the provider we can say

1 SUM 23 after heat treatment will unexpectedly develop cracking in the middle of the tensile

testing process and suddenly break

2 Itrsquos possible that in the process of heat treatment to the SUM 23 material the treatment was not

uniform and this will create a pre-loaded moment force on one side that pushes on the other side

of the specimen resulting in material deformation

3 In the process of attaching the strain gauges to the materials it is very easy to make errors due to

poor adhesion or sudden removal in the tensile testing process

For our second part of the independent study the following can be made

1 At the beginning of this independent study we had no idea what Bose-Einstein Condensate was

or what was its purpose After much literature we finally comprehended the basic principles to

put into practice for our research

2 Our systemrsquos basic working principles and equipmentrsquos complexity are a little difficult to grasp

but hopefully we were able to understand enough of it

3 Theoretically from relation between the power and current we can know the advantages and

disadvantages of AR Coating

4 We were able to assemble the system and run test on its functions Even though we were able to

do this there is still much more work left to do with this system

52 Recommendations

For the Tensile Testing the following can be said

1 Ask the provider to check on the process of heat treatment on the SUM 23 material and give

them the information we have gathered through our test so they can correct for the mechanical

properties found if any change is needed

2 To avoid the problem of the inaccuracy of the poor adhesion of strain gauges we can attach

multiple strain gauges to the same one specimen so as to correlate data and improve our results

For the AR Coating the following can be said

1 We need to make sure that there are no physical defects on the main body of the chamber so as to

achieve maximum efficiency in the vacuum process If there was then the vacuum will arrive to

certain point and then start to decrease

2 It would be preferable to add some sort of visual aid that will allow the user to check the inside of

the chamber without actually opening it This will help us determine at what times we should

manipulate the current to better evaporate the substrate

94

REFERENCES

[1] A L Window Strain Gauge Technology Elsevier Applied Science London and New York 2nd

Edition 1992

[2] CC Perry and HR Lissner Strain Gauge Primer McGraw-Hill Book Co Inc New York 1955

[3] James W Dally William F Riley McGraw-Hill 1978

[4] University of Colorado Boulder BEC - What is it and where did the idea come from

httpwwwcoloradoeduphysics2000becwhat_is_ithtml

[5] Ultraslow Light amp Bose-Einstein Condensates Two-way Control with Coherent Light amp Atom

Fields Harvard Hau Lab Dr Lene Vestergaard Hau Optics amp Photonics News 16 1995

[6] The Art of Taming Light Ultra-slow and Stopped Light Harvard Hau Lab Dr Lene

Vestergaard Hau Europhysics News 2004

[7] Nonlinear Optics Shocking Superfluids Harvard Hau Lab Dr Lene Vestergaard Hau Nature

Physics 2007

[8] Model P3 Strain Indicator and Recorder Instruction Manual Vishay Micro-Measurements 2005

[9] Granville-Phillips Series 375 Convectron Vacuum Gauge Controller Instruction Manual Brooks

Automation 2008

[10] Effect of Film Thickness on the Validity of the Sauerbrey Equation for Hydrated Polyelectrolyte

Films Vogt Lin Wu White 2004

[11] Quartz Crystal Microbalance Study of DNA Immobilization and Hybridization for DNA Sensor

Development Chang Zhao 2008

[12] Installation of Strain Gages with SR-4 PrecoatAdhesive Vishay Micro-Measurements 2005

[13] Strain Gauge Measurement ndash A Tutorial National Instruments 1998

[14] Correlation between Vickers Hardness Number and Yield Stress of Cold-Formed Products

Yavuz Tekkaya

[15] httpsenwikipediaorg

Page 82: PC Hinge Materials Testing and AR Laser Diode Coating

82

1 SQM-160 wire 5 Laser Connection 1 (Vin)

2 SQM-160 (G) 6 Laser Connection 2 (G)

3 K-Type-1 7 Laser Connection 3 (PD)

4 K-Type-2 8 Not In Use

The fully assembled chamber is shown in figure 4-9

Fig 4-9 Fully Assembled Chamber

422 Quartz Crystal Microbalance

For measuring the deposition on our target for coating we used the Inficon SQM-160 RateThickness

Monitor It is an easy to use instrument for measuring many types of thin-film coatings as shown in

figure 4-10

(a) Front Panel (b) Back Panel

Fig 4-10 Inficon SQM-160

83

Table 4-1 shows the technical specifications for this equipment

Number of sensors 2 Standard 4 additional optional

Sensor Frequency Range 40 MHz ~ 60 MHz

Reference Frequency Accuracy 002

Thickness Display Resolution 1 Aring

Thickness Resolution 015 Aring (Std) 0037 Aring (Hi Res)

Density of Stored Films 05-9999 gmcc

Tooling 10-399

Z-Factor 010-1000

Final Thickness 0000-9999k Aring

Measurement Period 15 to 2 sec

Simulation Mode Yes

Frequency Mode Yes

Rate Resolution 011 Arings

Dual Crystal Yes

Etch Mode Yes

Crystal Tooling 10-399

Crystal Fail Min Max 40 to 60 MHz 41 to 61 MHz

Power 100-120 200-240~plusmn10 nominal 20W

Operation Environment 0degC ~ 50degC

0 ~ 80 RH non-condensing

0 ~ 2000 meters

Class 1 Equipment

Pollution Degree 2

Rack Dimensions 885mm x 2127mm x 1969mm

Weight 27 kg

Table 4-1 Inficon SQM-160 RateThickness Monitor Specs

84

To the SQM-160 we need to connect an Oscillator We use the Sigma Instruments Remote Oscillator

Ser No 2 268 as shown in figure 4-11

Fig 4-11 Sigma Instruments Remote Oscillator

The connections diagram is shown in figure 4-12

Fig 4-12 SQM-160 Connections Diagram

85

423 Turbo Pump

For our experiments we used the Pfeiffer TCP 015 Electronic Drive Unit shown below in figure 4-13

Table 4-2 shows the technical specifications for this equipment

(a) Front Panel (b) Back Panel

Fig 4-13 Pfeiffer TCP 015 Electronic Drive

Connection Voltage (100V) 90-112

Mains Frequency 5060 Hz

Start-up Current 22 A

Nominal Frequency 1500 Hz

Rotation Speed 10V = 1500Hz plusmn2

Analog Output Current 10 V = 25 A plusmn 5

Rotation Speed Switchpoint 750 Hz

Works Setting 8 min

Permissible Ambient Temperature 0degC ~ 40degC

Dimensions Front Panel 1285mm x 1063mm

Insertion Length 227mm

Weight 27 Kg

Table 4-2 Pfeiffer TCP 015 Electronic Drive Specs

86

The connections diagram is shown in figure 4-14

Fig 4-14Connections Diagram for Pfeiffer TCP 015

To measure the pressure inside the chamber we use the Granville Phillips 375 Convectron Vacuum

Pressure Controller shown in figure 4-15

(a) Front Panel (b) Back Panel

Fig 4-15 Granville Phillips 375 Convectron

87

Its dimensions are shown in figure 4-16

Fig 4-16 Dimensions of Convectron

Table 4-3 shows the technical specifications for this equipment

Table 4-3 Granville Phillips 375 Convectron Vacuum Pressure Controller Specs

88

424 Multimeter

For our experiment we used the Keithley 2000 Digital Multimeter as shown in figure 4-17

(a) Front Panel (b) Back Panel

Fig 4-17 Keithley Model 2000 6-12-Digit Digital Multimeter

Its technical specifications are shown in table 4-4

Table 4-4 Keithley Model 2000 6-12-Digit Digital Multimeter Specs

89

43 Experiment Procedure

1 Connecting together the equipment and the chamber

(1) We first connect the resonator to the thickness monitor and connect the other side to the

chamber

(2) We now connect the flexible tubes to the turbo pump on one side and to the chamber on the

other

(3) We need to check that tubes are tightly connected to avoid any leaks in the vacuum pumping

process which will not allow us to get to our goal of Torr As shown in figure 4-18

(4) Connect the convectron to the system as shown in figure 4-19

Fig 4-18 checking for leaks using alcohol

Fig 4-19 Convectron attached to System

90

(5) Attach the clamps of the Multimeter to the bottom of the chamber as shown in figure 4-20

(6) Place the Quartz crystal in place

(7) Close tight vacuum chamber

(8) Connect all electrical appliances to power source

Fig 4-20 Multimeter Connections

2 Starting up the System

(1) We turn on all the devices as such Check all systems are ready to function Reset all values

that might be left over from previous tests

(2) Start the thickness monitor and set all values for this experiment In our case we got to testing

the system but not actual coating So we used the simulation mode of the thickness monitor as

shown in figure 4-21

Fig 4-21 Simulation Mode

91

(3) Start the turbo pump Make sure the lid on the vacuum chamber is tightly closed

(4) Start convectron and record initial pressure

(5) Start Multimeter and record initial current

3 Coating Process

(1) If we have the deposition material inside the filament boat the power source for the high

current must be started as well

(2) Record all initial values for thickness current pressure

(3) For an ideal experiment we need a thickness of around 101 nm a pressure of Torr and

a current of 300 A

44 Results

From previous experiments we have shown that we can turn a LED into a laser by means of AR

Coating In figure 4-22 shown below we can compare the actual results of a Diode before and after AR

coating From the blue line we can see that when the diode is at a current of 15mA its light will change

from LED to laser and if we look at the red line its critical current is around 30 to 35 mA

Fig 4-22 AR Coating Comparison for Laser Diodes

This means that the light emitted is not as strong as if the diode had been coated because inside the

chamber there must be some excitation first so the reflectivity of both sides inside the diode must be high

So because of the coating in one of the sides we have opened a door and let the light come out so the

critical current is risen as such and will be higher value than that of before the coating

92

In the following figures we can see the difference between before and after coating in a material The

thickness is around 1016 nm for this material

Fig 4-23 Before Coating

Fig 4-24 After Coating

93

Chapter 5 CONCLUSIONS AND RECOMMENDATIONS

51 Conclusions

For the first part of this independent study taking into consideration the data that came out of our

research and that sent by the provider we can say

1 SUM 23 after heat treatment will unexpectedly develop cracking in the middle of the tensile

testing process and suddenly break

2 Itrsquos possible that in the process of heat treatment to the SUM 23 material the treatment was not

uniform and this will create a pre-loaded moment force on one side that pushes on the other side

of the specimen resulting in material deformation

3 In the process of attaching the strain gauges to the materials it is very easy to make errors due to

poor adhesion or sudden removal in the tensile testing process

For our second part of the independent study the following can be made

1 At the beginning of this independent study we had no idea what Bose-Einstein Condensate was

or what was its purpose After much literature we finally comprehended the basic principles to

put into practice for our research

2 Our systemrsquos basic working principles and equipmentrsquos complexity are a little difficult to grasp

but hopefully we were able to understand enough of it

3 Theoretically from relation between the power and current we can know the advantages and

disadvantages of AR Coating

4 We were able to assemble the system and run test on its functions Even though we were able to

do this there is still much more work left to do with this system

52 Recommendations

For the Tensile Testing the following can be said

1 Ask the provider to check on the process of heat treatment on the SUM 23 material and give

them the information we have gathered through our test so they can correct for the mechanical

properties found if any change is needed

2 To avoid the problem of the inaccuracy of the poor adhesion of strain gauges we can attach

multiple strain gauges to the same one specimen so as to correlate data and improve our results

For the AR Coating the following can be said

1 We need to make sure that there are no physical defects on the main body of the chamber so as to

achieve maximum efficiency in the vacuum process If there was then the vacuum will arrive to

certain point and then start to decrease

2 It would be preferable to add some sort of visual aid that will allow the user to check the inside of

the chamber without actually opening it This will help us determine at what times we should

manipulate the current to better evaporate the substrate

94

REFERENCES

[1] A L Window Strain Gauge Technology Elsevier Applied Science London and New York 2nd

Edition 1992

[2] CC Perry and HR Lissner Strain Gauge Primer McGraw-Hill Book Co Inc New York 1955

[3] James W Dally William F Riley McGraw-Hill 1978

[4] University of Colorado Boulder BEC - What is it and where did the idea come from

httpwwwcoloradoeduphysics2000becwhat_is_ithtml

[5] Ultraslow Light amp Bose-Einstein Condensates Two-way Control with Coherent Light amp Atom

Fields Harvard Hau Lab Dr Lene Vestergaard Hau Optics amp Photonics News 16 1995

[6] The Art of Taming Light Ultra-slow and Stopped Light Harvard Hau Lab Dr Lene

Vestergaard Hau Europhysics News 2004

[7] Nonlinear Optics Shocking Superfluids Harvard Hau Lab Dr Lene Vestergaard Hau Nature

Physics 2007

[8] Model P3 Strain Indicator and Recorder Instruction Manual Vishay Micro-Measurements 2005

[9] Granville-Phillips Series 375 Convectron Vacuum Gauge Controller Instruction Manual Brooks

Automation 2008

[10] Effect of Film Thickness on the Validity of the Sauerbrey Equation for Hydrated Polyelectrolyte

Films Vogt Lin Wu White 2004

[11] Quartz Crystal Microbalance Study of DNA Immobilization and Hybridization for DNA Sensor

Development Chang Zhao 2008

[12] Installation of Strain Gages with SR-4 PrecoatAdhesive Vishay Micro-Measurements 2005

[13] Strain Gauge Measurement ndash A Tutorial National Instruments 1998

[14] Correlation between Vickers Hardness Number and Yield Stress of Cold-Formed Products

Yavuz Tekkaya

[15] httpsenwikipediaorg

Page 83: PC Hinge Materials Testing and AR Laser Diode Coating

83

Table 4-1 shows the technical specifications for this equipment

Number of sensors 2 Standard 4 additional optional

Sensor Frequency Range 40 MHz ~ 60 MHz

Reference Frequency Accuracy 002

Thickness Display Resolution 1 Aring

Thickness Resolution 015 Aring (Std) 0037 Aring (Hi Res)

Density of Stored Films 05-9999 gmcc

Tooling 10-399

Z-Factor 010-1000

Final Thickness 0000-9999k Aring

Measurement Period 15 to 2 sec

Simulation Mode Yes

Frequency Mode Yes

Rate Resolution 011 Arings

Dual Crystal Yes

Etch Mode Yes

Crystal Tooling 10-399

Crystal Fail Min Max 40 to 60 MHz 41 to 61 MHz

Power 100-120 200-240~plusmn10 nominal 20W

Operation Environment 0degC ~ 50degC

0 ~ 80 RH non-condensing

0 ~ 2000 meters

Class 1 Equipment

Pollution Degree 2

Rack Dimensions 885mm x 2127mm x 1969mm

Weight 27 kg

Table 4-1 Inficon SQM-160 RateThickness Monitor Specs

84

To the SQM-160 we need to connect an Oscillator We use the Sigma Instruments Remote Oscillator

Ser No 2 268 as shown in figure 4-11

Fig 4-11 Sigma Instruments Remote Oscillator

The connections diagram is shown in figure 4-12

Fig 4-12 SQM-160 Connections Diagram

85

423 Turbo Pump

For our experiments we used the Pfeiffer TCP 015 Electronic Drive Unit shown below in figure 4-13

Table 4-2 shows the technical specifications for this equipment

(a) Front Panel (b) Back Panel

Fig 4-13 Pfeiffer TCP 015 Electronic Drive

Connection Voltage (100V) 90-112

Mains Frequency 5060 Hz

Start-up Current 22 A

Nominal Frequency 1500 Hz

Rotation Speed 10V = 1500Hz plusmn2

Analog Output Current 10 V = 25 A plusmn 5

Rotation Speed Switchpoint 750 Hz

Works Setting 8 min

Permissible Ambient Temperature 0degC ~ 40degC

Dimensions Front Panel 1285mm x 1063mm

Insertion Length 227mm

Weight 27 Kg

Table 4-2 Pfeiffer TCP 015 Electronic Drive Specs

86

The connections diagram is shown in figure 4-14

Fig 4-14Connections Diagram for Pfeiffer TCP 015

To measure the pressure inside the chamber we use the Granville Phillips 375 Convectron Vacuum

Pressure Controller shown in figure 4-15

(a) Front Panel (b) Back Panel

Fig 4-15 Granville Phillips 375 Convectron

87

Its dimensions are shown in figure 4-16

Fig 4-16 Dimensions of Convectron

Table 4-3 shows the technical specifications for this equipment

Table 4-3 Granville Phillips 375 Convectron Vacuum Pressure Controller Specs

88

424 Multimeter

For our experiment we used the Keithley 2000 Digital Multimeter as shown in figure 4-17

(a) Front Panel (b) Back Panel

Fig 4-17 Keithley Model 2000 6-12-Digit Digital Multimeter

Its technical specifications are shown in table 4-4

Table 4-4 Keithley Model 2000 6-12-Digit Digital Multimeter Specs

89

43 Experiment Procedure

1 Connecting together the equipment and the chamber

(1) We first connect the resonator to the thickness monitor and connect the other side to the

chamber

(2) We now connect the flexible tubes to the turbo pump on one side and to the chamber on the

other

(3) We need to check that tubes are tightly connected to avoid any leaks in the vacuum pumping

process which will not allow us to get to our goal of Torr As shown in figure 4-18

(4) Connect the convectron to the system as shown in figure 4-19

Fig 4-18 checking for leaks using alcohol

Fig 4-19 Convectron attached to System

90

(5) Attach the clamps of the Multimeter to the bottom of the chamber as shown in figure 4-20

(6) Place the Quartz crystal in place

(7) Close tight vacuum chamber

(8) Connect all electrical appliances to power source

Fig 4-20 Multimeter Connections

2 Starting up the System

(1) We turn on all the devices as such Check all systems are ready to function Reset all values

that might be left over from previous tests

(2) Start the thickness monitor and set all values for this experiment In our case we got to testing

the system but not actual coating So we used the simulation mode of the thickness monitor as

shown in figure 4-21

Fig 4-21 Simulation Mode

91

(3) Start the turbo pump Make sure the lid on the vacuum chamber is tightly closed

(4) Start convectron and record initial pressure

(5) Start Multimeter and record initial current

3 Coating Process

(1) If we have the deposition material inside the filament boat the power source for the high

current must be started as well

(2) Record all initial values for thickness current pressure

(3) For an ideal experiment we need a thickness of around 101 nm a pressure of Torr and

a current of 300 A

44 Results

From previous experiments we have shown that we can turn a LED into a laser by means of AR

Coating In figure 4-22 shown below we can compare the actual results of a Diode before and after AR

coating From the blue line we can see that when the diode is at a current of 15mA its light will change

from LED to laser and if we look at the red line its critical current is around 30 to 35 mA

Fig 4-22 AR Coating Comparison for Laser Diodes

This means that the light emitted is not as strong as if the diode had been coated because inside the

chamber there must be some excitation first so the reflectivity of both sides inside the diode must be high

So because of the coating in one of the sides we have opened a door and let the light come out so the

critical current is risen as such and will be higher value than that of before the coating

92

In the following figures we can see the difference between before and after coating in a material The

thickness is around 1016 nm for this material

Fig 4-23 Before Coating

Fig 4-24 After Coating

93

Chapter 5 CONCLUSIONS AND RECOMMENDATIONS

51 Conclusions

For the first part of this independent study taking into consideration the data that came out of our

research and that sent by the provider we can say

1 SUM 23 after heat treatment will unexpectedly develop cracking in the middle of the tensile

testing process and suddenly break

2 Itrsquos possible that in the process of heat treatment to the SUM 23 material the treatment was not

uniform and this will create a pre-loaded moment force on one side that pushes on the other side

of the specimen resulting in material deformation

3 In the process of attaching the strain gauges to the materials it is very easy to make errors due to

poor adhesion or sudden removal in the tensile testing process

For our second part of the independent study the following can be made

1 At the beginning of this independent study we had no idea what Bose-Einstein Condensate was

or what was its purpose After much literature we finally comprehended the basic principles to

put into practice for our research

2 Our systemrsquos basic working principles and equipmentrsquos complexity are a little difficult to grasp

but hopefully we were able to understand enough of it

3 Theoretically from relation between the power and current we can know the advantages and

disadvantages of AR Coating

4 We were able to assemble the system and run test on its functions Even though we were able to

do this there is still much more work left to do with this system

52 Recommendations

For the Tensile Testing the following can be said

1 Ask the provider to check on the process of heat treatment on the SUM 23 material and give

them the information we have gathered through our test so they can correct for the mechanical

properties found if any change is needed

2 To avoid the problem of the inaccuracy of the poor adhesion of strain gauges we can attach

multiple strain gauges to the same one specimen so as to correlate data and improve our results

For the AR Coating the following can be said

1 We need to make sure that there are no physical defects on the main body of the chamber so as to

achieve maximum efficiency in the vacuum process If there was then the vacuum will arrive to

certain point and then start to decrease

2 It would be preferable to add some sort of visual aid that will allow the user to check the inside of

the chamber without actually opening it This will help us determine at what times we should

manipulate the current to better evaporate the substrate

94

REFERENCES

[1] A L Window Strain Gauge Technology Elsevier Applied Science London and New York 2nd

Edition 1992

[2] CC Perry and HR Lissner Strain Gauge Primer McGraw-Hill Book Co Inc New York 1955

[3] James W Dally William F Riley McGraw-Hill 1978

[4] University of Colorado Boulder BEC - What is it and where did the idea come from

httpwwwcoloradoeduphysics2000becwhat_is_ithtml

[5] Ultraslow Light amp Bose-Einstein Condensates Two-way Control with Coherent Light amp Atom

Fields Harvard Hau Lab Dr Lene Vestergaard Hau Optics amp Photonics News 16 1995

[6] The Art of Taming Light Ultra-slow and Stopped Light Harvard Hau Lab Dr Lene

Vestergaard Hau Europhysics News 2004

[7] Nonlinear Optics Shocking Superfluids Harvard Hau Lab Dr Lene Vestergaard Hau Nature

Physics 2007

[8] Model P3 Strain Indicator and Recorder Instruction Manual Vishay Micro-Measurements 2005

[9] Granville-Phillips Series 375 Convectron Vacuum Gauge Controller Instruction Manual Brooks

Automation 2008

[10] Effect of Film Thickness on the Validity of the Sauerbrey Equation for Hydrated Polyelectrolyte

Films Vogt Lin Wu White 2004

[11] Quartz Crystal Microbalance Study of DNA Immobilization and Hybridization for DNA Sensor

Development Chang Zhao 2008

[12] Installation of Strain Gages with SR-4 PrecoatAdhesive Vishay Micro-Measurements 2005

[13] Strain Gauge Measurement ndash A Tutorial National Instruments 1998

[14] Correlation between Vickers Hardness Number and Yield Stress of Cold-Formed Products

Yavuz Tekkaya

[15] httpsenwikipediaorg

Page 84: PC Hinge Materials Testing and AR Laser Diode Coating

84

To the SQM-160 we need to connect an Oscillator We use the Sigma Instruments Remote Oscillator

Ser No 2 268 as shown in figure 4-11

Fig 4-11 Sigma Instruments Remote Oscillator

The connections diagram is shown in figure 4-12

Fig 4-12 SQM-160 Connections Diagram

85

423 Turbo Pump

For our experiments we used the Pfeiffer TCP 015 Electronic Drive Unit shown below in figure 4-13

Table 4-2 shows the technical specifications for this equipment

(a) Front Panel (b) Back Panel

Fig 4-13 Pfeiffer TCP 015 Electronic Drive

Connection Voltage (100V) 90-112

Mains Frequency 5060 Hz

Start-up Current 22 A

Nominal Frequency 1500 Hz

Rotation Speed 10V = 1500Hz plusmn2

Analog Output Current 10 V = 25 A plusmn 5

Rotation Speed Switchpoint 750 Hz

Works Setting 8 min

Permissible Ambient Temperature 0degC ~ 40degC

Dimensions Front Panel 1285mm x 1063mm

Insertion Length 227mm

Weight 27 Kg

Table 4-2 Pfeiffer TCP 015 Electronic Drive Specs

86

The connections diagram is shown in figure 4-14

Fig 4-14Connections Diagram for Pfeiffer TCP 015

To measure the pressure inside the chamber we use the Granville Phillips 375 Convectron Vacuum

Pressure Controller shown in figure 4-15

(a) Front Panel (b) Back Panel

Fig 4-15 Granville Phillips 375 Convectron

87

Its dimensions are shown in figure 4-16

Fig 4-16 Dimensions of Convectron

Table 4-3 shows the technical specifications for this equipment

Table 4-3 Granville Phillips 375 Convectron Vacuum Pressure Controller Specs

88

424 Multimeter

For our experiment we used the Keithley 2000 Digital Multimeter as shown in figure 4-17

(a) Front Panel (b) Back Panel

Fig 4-17 Keithley Model 2000 6-12-Digit Digital Multimeter

Its technical specifications are shown in table 4-4

Table 4-4 Keithley Model 2000 6-12-Digit Digital Multimeter Specs

89

43 Experiment Procedure

1 Connecting together the equipment and the chamber

(1) We first connect the resonator to the thickness monitor and connect the other side to the

chamber

(2) We now connect the flexible tubes to the turbo pump on one side and to the chamber on the

other

(3) We need to check that tubes are tightly connected to avoid any leaks in the vacuum pumping

process which will not allow us to get to our goal of Torr As shown in figure 4-18

(4) Connect the convectron to the system as shown in figure 4-19

Fig 4-18 checking for leaks using alcohol

Fig 4-19 Convectron attached to System

90

(5) Attach the clamps of the Multimeter to the bottom of the chamber as shown in figure 4-20

(6) Place the Quartz crystal in place

(7) Close tight vacuum chamber

(8) Connect all electrical appliances to power source

Fig 4-20 Multimeter Connections

2 Starting up the System

(1) We turn on all the devices as such Check all systems are ready to function Reset all values

that might be left over from previous tests

(2) Start the thickness monitor and set all values for this experiment In our case we got to testing

the system but not actual coating So we used the simulation mode of the thickness monitor as

shown in figure 4-21

Fig 4-21 Simulation Mode

91

(3) Start the turbo pump Make sure the lid on the vacuum chamber is tightly closed

(4) Start convectron and record initial pressure

(5) Start Multimeter and record initial current

3 Coating Process

(1) If we have the deposition material inside the filament boat the power source for the high

current must be started as well

(2) Record all initial values for thickness current pressure

(3) For an ideal experiment we need a thickness of around 101 nm a pressure of Torr and

a current of 300 A

44 Results

From previous experiments we have shown that we can turn a LED into a laser by means of AR

Coating In figure 4-22 shown below we can compare the actual results of a Diode before and after AR

coating From the blue line we can see that when the diode is at a current of 15mA its light will change

from LED to laser and if we look at the red line its critical current is around 30 to 35 mA

Fig 4-22 AR Coating Comparison for Laser Diodes

This means that the light emitted is not as strong as if the diode had been coated because inside the

chamber there must be some excitation first so the reflectivity of both sides inside the diode must be high

So because of the coating in one of the sides we have opened a door and let the light come out so the

critical current is risen as such and will be higher value than that of before the coating

92

In the following figures we can see the difference between before and after coating in a material The

thickness is around 1016 nm for this material

Fig 4-23 Before Coating

Fig 4-24 After Coating

93

Chapter 5 CONCLUSIONS AND RECOMMENDATIONS

51 Conclusions

For the first part of this independent study taking into consideration the data that came out of our

research and that sent by the provider we can say

1 SUM 23 after heat treatment will unexpectedly develop cracking in the middle of the tensile

testing process and suddenly break

2 Itrsquos possible that in the process of heat treatment to the SUM 23 material the treatment was not

uniform and this will create a pre-loaded moment force on one side that pushes on the other side

of the specimen resulting in material deformation

3 In the process of attaching the strain gauges to the materials it is very easy to make errors due to

poor adhesion or sudden removal in the tensile testing process

For our second part of the independent study the following can be made

1 At the beginning of this independent study we had no idea what Bose-Einstein Condensate was

or what was its purpose After much literature we finally comprehended the basic principles to

put into practice for our research

2 Our systemrsquos basic working principles and equipmentrsquos complexity are a little difficult to grasp

but hopefully we were able to understand enough of it

3 Theoretically from relation between the power and current we can know the advantages and

disadvantages of AR Coating

4 We were able to assemble the system and run test on its functions Even though we were able to

do this there is still much more work left to do with this system

52 Recommendations

For the Tensile Testing the following can be said

1 Ask the provider to check on the process of heat treatment on the SUM 23 material and give

them the information we have gathered through our test so they can correct for the mechanical

properties found if any change is needed

2 To avoid the problem of the inaccuracy of the poor adhesion of strain gauges we can attach

multiple strain gauges to the same one specimen so as to correlate data and improve our results

For the AR Coating the following can be said

1 We need to make sure that there are no physical defects on the main body of the chamber so as to

achieve maximum efficiency in the vacuum process If there was then the vacuum will arrive to

certain point and then start to decrease

2 It would be preferable to add some sort of visual aid that will allow the user to check the inside of

the chamber without actually opening it This will help us determine at what times we should

manipulate the current to better evaporate the substrate

94

REFERENCES

[1] A L Window Strain Gauge Technology Elsevier Applied Science London and New York 2nd

Edition 1992

[2] CC Perry and HR Lissner Strain Gauge Primer McGraw-Hill Book Co Inc New York 1955

[3] James W Dally William F Riley McGraw-Hill 1978

[4] University of Colorado Boulder BEC - What is it and where did the idea come from

httpwwwcoloradoeduphysics2000becwhat_is_ithtml

[5] Ultraslow Light amp Bose-Einstein Condensates Two-way Control with Coherent Light amp Atom

Fields Harvard Hau Lab Dr Lene Vestergaard Hau Optics amp Photonics News 16 1995

[6] The Art of Taming Light Ultra-slow and Stopped Light Harvard Hau Lab Dr Lene

Vestergaard Hau Europhysics News 2004

[7] Nonlinear Optics Shocking Superfluids Harvard Hau Lab Dr Lene Vestergaard Hau Nature

Physics 2007

[8] Model P3 Strain Indicator and Recorder Instruction Manual Vishay Micro-Measurements 2005

[9] Granville-Phillips Series 375 Convectron Vacuum Gauge Controller Instruction Manual Brooks

Automation 2008

[10] Effect of Film Thickness on the Validity of the Sauerbrey Equation for Hydrated Polyelectrolyte

Films Vogt Lin Wu White 2004

[11] Quartz Crystal Microbalance Study of DNA Immobilization and Hybridization for DNA Sensor

Development Chang Zhao 2008

[12] Installation of Strain Gages with SR-4 PrecoatAdhesive Vishay Micro-Measurements 2005

[13] Strain Gauge Measurement ndash A Tutorial National Instruments 1998

[14] Correlation between Vickers Hardness Number and Yield Stress of Cold-Formed Products

Yavuz Tekkaya

[15] httpsenwikipediaorg

Page 85: PC Hinge Materials Testing and AR Laser Diode Coating

85

423 Turbo Pump

For our experiments we used the Pfeiffer TCP 015 Electronic Drive Unit shown below in figure 4-13

Table 4-2 shows the technical specifications for this equipment

(a) Front Panel (b) Back Panel

Fig 4-13 Pfeiffer TCP 015 Electronic Drive

Connection Voltage (100V) 90-112

Mains Frequency 5060 Hz

Start-up Current 22 A

Nominal Frequency 1500 Hz

Rotation Speed 10V = 1500Hz plusmn2

Analog Output Current 10 V = 25 A plusmn 5

Rotation Speed Switchpoint 750 Hz

Works Setting 8 min

Permissible Ambient Temperature 0degC ~ 40degC

Dimensions Front Panel 1285mm x 1063mm

Insertion Length 227mm

Weight 27 Kg

Table 4-2 Pfeiffer TCP 015 Electronic Drive Specs

86

The connections diagram is shown in figure 4-14

Fig 4-14Connections Diagram for Pfeiffer TCP 015

To measure the pressure inside the chamber we use the Granville Phillips 375 Convectron Vacuum

Pressure Controller shown in figure 4-15

(a) Front Panel (b) Back Panel

Fig 4-15 Granville Phillips 375 Convectron

87

Its dimensions are shown in figure 4-16

Fig 4-16 Dimensions of Convectron

Table 4-3 shows the technical specifications for this equipment

Table 4-3 Granville Phillips 375 Convectron Vacuum Pressure Controller Specs

88

424 Multimeter

For our experiment we used the Keithley 2000 Digital Multimeter as shown in figure 4-17

(a) Front Panel (b) Back Panel

Fig 4-17 Keithley Model 2000 6-12-Digit Digital Multimeter

Its technical specifications are shown in table 4-4

Table 4-4 Keithley Model 2000 6-12-Digit Digital Multimeter Specs

89

43 Experiment Procedure

1 Connecting together the equipment and the chamber

(1) We first connect the resonator to the thickness monitor and connect the other side to the

chamber

(2) We now connect the flexible tubes to the turbo pump on one side and to the chamber on the

other

(3) We need to check that tubes are tightly connected to avoid any leaks in the vacuum pumping

process which will not allow us to get to our goal of Torr As shown in figure 4-18

(4) Connect the convectron to the system as shown in figure 4-19

Fig 4-18 checking for leaks using alcohol

Fig 4-19 Convectron attached to System

90

(5) Attach the clamps of the Multimeter to the bottom of the chamber as shown in figure 4-20

(6) Place the Quartz crystal in place

(7) Close tight vacuum chamber

(8) Connect all electrical appliances to power source

Fig 4-20 Multimeter Connections

2 Starting up the System

(1) We turn on all the devices as such Check all systems are ready to function Reset all values

that might be left over from previous tests

(2) Start the thickness monitor and set all values for this experiment In our case we got to testing

the system but not actual coating So we used the simulation mode of the thickness monitor as

shown in figure 4-21

Fig 4-21 Simulation Mode

91

(3) Start the turbo pump Make sure the lid on the vacuum chamber is tightly closed

(4) Start convectron and record initial pressure

(5) Start Multimeter and record initial current

3 Coating Process

(1) If we have the deposition material inside the filament boat the power source for the high

current must be started as well

(2) Record all initial values for thickness current pressure

(3) For an ideal experiment we need a thickness of around 101 nm a pressure of Torr and

a current of 300 A

44 Results

From previous experiments we have shown that we can turn a LED into a laser by means of AR

Coating In figure 4-22 shown below we can compare the actual results of a Diode before and after AR

coating From the blue line we can see that when the diode is at a current of 15mA its light will change

from LED to laser and if we look at the red line its critical current is around 30 to 35 mA

Fig 4-22 AR Coating Comparison for Laser Diodes

This means that the light emitted is not as strong as if the diode had been coated because inside the

chamber there must be some excitation first so the reflectivity of both sides inside the diode must be high

So because of the coating in one of the sides we have opened a door and let the light come out so the

critical current is risen as such and will be higher value than that of before the coating

92

In the following figures we can see the difference between before and after coating in a material The

thickness is around 1016 nm for this material

Fig 4-23 Before Coating

Fig 4-24 After Coating

93

Chapter 5 CONCLUSIONS AND RECOMMENDATIONS

51 Conclusions

For the first part of this independent study taking into consideration the data that came out of our

research and that sent by the provider we can say

1 SUM 23 after heat treatment will unexpectedly develop cracking in the middle of the tensile

testing process and suddenly break

2 Itrsquos possible that in the process of heat treatment to the SUM 23 material the treatment was not

uniform and this will create a pre-loaded moment force on one side that pushes on the other side

of the specimen resulting in material deformation

3 In the process of attaching the strain gauges to the materials it is very easy to make errors due to

poor adhesion or sudden removal in the tensile testing process

For our second part of the independent study the following can be made

1 At the beginning of this independent study we had no idea what Bose-Einstein Condensate was

or what was its purpose After much literature we finally comprehended the basic principles to

put into practice for our research

2 Our systemrsquos basic working principles and equipmentrsquos complexity are a little difficult to grasp

but hopefully we were able to understand enough of it

3 Theoretically from relation between the power and current we can know the advantages and

disadvantages of AR Coating

4 We were able to assemble the system and run test on its functions Even though we were able to

do this there is still much more work left to do with this system

52 Recommendations

For the Tensile Testing the following can be said

1 Ask the provider to check on the process of heat treatment on the SUM 23 material and give

them the information we have gathered through our test so they can correct for the mechanical

properties found if any change is needed

2 To avoid the problem of the inaccuracy of the poor adhesion of strain gauges we can attach

multiple strain gauges to the same one specimen so as to correlate data and improve our results

For the AR Coating the following can be said

1 We need to make sure that there are no physical defects on the main body of the chamber so as to

achieve maximum efficiency in the vacuum process If there was then the vacuum will arrive to

certain point and then start to decrease

2 It would be preferable to add some sort of visual aid that will allow the user to check the inside of

the chamber without actually opening it This will help us determine at what times we should

manipulate the current to better evaporate the substrate

94

REFERENCES

[1] A L Window Strain Gauge Technology Elsevier Applied Science London and New York 2nd

Edition 1992

[2] CC Perry and HR Lissner Strain Gauge Primer McGraw-Hill Book Co Inc New York 1955

[3] James W Dally William F Riley McGraw-Hill 1978

[4] University of Colorado Boulder BEC - What is it and where did the idea come from

httpwwwcoloradoeduphysics2000becwhat_is_ithtml

[5] Ultraslow Light amp Bose-Einstein Condensates Two-way Control with Coherent Light amp Atom

Fields Harvard Hau Lab Dr Lene Vestergaard Hau Optics amp Photonics News 16 1995

[6] The Art of Taming Light Ultra-slow and Stopped Light Harvard Hau Lab Dr Lene

Vestergaard Hau Europhysics News 2004

[7] Nonlinear Optics Shocking Superfluids Harvard Hau Lab Dr Lene Vestergaard Hau Nature

Physics 2007

[8] Model P3 Strain Indicator and Recorder Instruction Manual Vishay Micro-Measurements 2005

[9] Granville-Phillips Series 375 Convectron Vacuum Gauge Controller Instruction Manual Brooks

Automation 2008

[10] Effect of Film Thickness on the Validity of the Sauerbrey Equation for Hydrated Polyelectrolyte

Films Vogt Lin Wu White 2004

[11] Quartz Crystal Microbalance Study of DNA Immobilization and Hybridization for DNA Sensor

Development Chang Zhao 2008

[12] Installation of Strain Gages with SR-4 PrecoatAdhesive Vishay Micro-Measurements 2005

[13] Strain Gauge Measurement ndash A Tutorial National Instruments 1998

[14] Correlation between Vickers Hardness Number and Yield Stress of Cold-Formed Products

Yavuz Tekkaya

[15] httpsenwikipediaorg

Page 86: PC Hinge Materials Testing and AR Laser Diode Coating

86

The connections diagram is shown in figure 4-14

Fig 4-14Connections Diagram for Pfeiffer TCP 015

To measure the pressure inside the chamber we use the Granville Phillips 375 Convectron Vacuum

Pressure Controller shown in figure 4-15

(a) Front Panel (b) Back Panel

Fig 4-15 Granville Phillips 375 Convectron

87

Its dimensions are shown in figure 4-16

Fig 4-16 Dimensions of Convectron

Table 4-3 shows the technical specifications for this equipment

Table 4-3 Granville Phillips 375 Convectron Vacuum Pressure Controller Specs

88

424 Multimeter

For our experiment we used the Keithley 2000 Digital Multimeter as shown in figure 4-17

(a) Front Panel (b) Back Panel

Fig 4-17 Keithley Model 2000 6-12-Digit Digital Multimeter

Its technical specifications are shown in table 4-4

Table 4-4 Keithley Model 2000 6-12-Digit Digital Multimeter Specs

89

43 Experiment Procedure

1 Connecting together the equipment and the chamber

(1) We first connect the resonator to the thickness monitor and connect the other side to the

chamber

(2) We now connect the flexible tubes to the turbo pump on one side and to the chamber on the

other

(3) We need to check that tubes are tightly connected to avoid any leaks in the vacuum pumping

process which will not allow us to get to our goal of Torr As shown in figure 4-18

(4) Connect the convectron to the system as shown in figure 4-19

Fig 4-18 checking for leaks using alcohol

Fig 4-19 Convectron attached to System

90

(5) Attach the clamps of the Multimeter to the bottom of the chamber as shown in figure 4-20

(6) Place the Quartz crystal in place

(7) Close tight vacuum chamber

(8) Connect all electrical appliances to power source

Fig 4-20 Multimeter Connections

2 Starting up the System

(1) We turn on all the devices as such Check all systems are ready to function Reset all values

that might be left over from previous tests

(2) Start the thickness monitor and set all values for this experiment In our case we got to testing

the system but not actual coating So we used the simulation mode of the thickness monitor as

shown in figure 4-21

Fig 4-21 Simulation Mode

91

(3) Start the turbo pump Make sure the lid on the vacuum chamber is tightly closed

(4) Start convectron and record initial pressure

(5) Start Multimeter and record initial current

3 Coating Process

(1) If we have the deposition material inside the filament boat the power source for the high

current must be started as well

(2) Record all initial values for thickness current pressure

(3) For an ideal experiment we need a thickness of around 101 nm a pressure of Torr and

a current of 300 A

44 Results

From previous experiments we have shown that we can turn a LED into a laser by means of AR

Coating In figure 4-22 shown below we can compare the actual results of a Diode before and after AR

coating From the blue line we can see that when the diode is at a current of 15mA its light will change

from LED to laser and if we look at the red line its critical current is around 30 to 35 mA

Fig 4-22 AR Coating Comparison for Laser Diodes

This means that the light emitted is not as strong as if the diode had been coated because inside the

chamber there must be some excitation first so the reflectivity of both sides inside the diode must be high

So because of the coating in one of the sides we have opened a door and let the light come out so the

critical current is risen as such and will be higher value than that of before the coating

92

In the following figures we can see the difference between before and after coating in a material The

thickness is around 1016 nm for this material

Fig 4-23 Before Coating

Fig 4-24 After Coating

93

Chapter 5 CONCLUSIONS AND RECOMMENDATIONS

51 Conclusions

For the first part of this independent study taking into consideration the data that came out of our

research and that sent by the provider we can say

1 SUM 23 after heat treatment will unexpectedly develop cracking in the middle of the tensile

testing process and suddenly break

2 Itrsquos possible that in the process of heat treatment to the SUM 23 material the treatment was not

uniform and this will create a pre-loaded moment force on one side that pushes on the other side

of the specimen resulting in material deformation

3 In the process of attaching the strain gauges to the materials it is very easy to make errors due to

poor adhesion or sudden removal in the tensile testing process

For our second part of the independent study the following can be made

1 At the beginning of this independent study we had no idea what Bose-Einstein Condensate was

or what was its purpose After much literature we finally comprehended the basic principles to

put into practice for our research

2 Our systemrsquos basic working principles and equipmentrsquos complexity are a little difficult to grasp

but hopefully we were able to understand enough of it

3 Theoretically from relation between the power and current we can know the advantages and

disadvantages of AR Coating

4 We were able to assemble the system and run test on its functions Even though we were able to

do this there is still much more work left to do with this system

52 Recommendations

For the Tensile Testing the following can be said

1 Ask the provider to check on the process of heat treatment on the SUM 23 material and give

them the information we have gathered through our test so they can correct for the mechanical

properties found if any change is needed

2 To avoid the problem of the inaccuracy of the poor adhesion of strain gauges we can attach

multiple strain gauges to the same one specimen so as to correlate data and improve our results

For the AR Coating the following can be said

1 We need to make sure that there are no physical defects on the main body of the chamber so as to

achieve maximum efficiency in the vacuum process If there was then the vacuum will arrive to

certain point and then start to decrease

2 It would be preferable to add some sort of visual aid that will allow the user to check the inside of

the chamber without actually opening it This will help us determine at what times we should

manipulate the current to better evaporate the substrate

94

REFERENCES

[1] A L Window Strain Gauge Technology Elsevier Applied Science London and New York 2nd

Edition 1992

[2] CC Perry and HR Lissner Strain Gauge Primer McGraw-Hill Book Co Inc New York 1955

[3] James W Dally William F Riley McGraw-Hill 1978

[4] University of Colorado Boulder BEC - What is it and where did the idea come from

httpwwwcoloradoeduphysics2000becwhat_is_ithtml

[5] Ultraslow Light amp Bose-Einstein Condensates Two-way Control with Coherent Light amp Atom

Fields Harvard Hau Lab Dr Lene Vestergaard Hau Optics amp Photonics News 16 1995

[6] The Art of Taming Light Ultra-slow and Stopped Light Harvard Hau Lab Dr Lene

Vestergaard Hau Europhysics News 2004

[7] Nonlinear Optics Shocking Superfluids Harvard Hau Lab Dr Lene Vestergaard Hau Nature

Physics 2007

[8] Model P3 Strain Indicator and Recorder Instruction Manual Vishay Micro-Measurements 2005

[9] Granville-Phillips Series 375 Convectron Vacuum Gauge Controller Instruction Manual Brooks

Automation 2008

[10] Effect of Film Thickness on the Validity of the Sauerbrey Equation for Hydrated Polyelectrolyte

Films Vogt Lin Wu White 2004

[11] Quartz Crystal Microbalance Study of DNA Immobilization and Hybridization for DNA Sensor

Development Chang Zhao 2008

[12] Installation of Strain Gages with SR-4 PrecoatAdhesive Vishay Micro-Measurements 2005

[13] Strain Gauge Measurement ndash A Tutorial National Instruments 1998

[14] Correlation between Vickers Hardness Number and Yield Stress of Cold-Formed Products

Yavuz Tekkaya

[15] httpsenwikipediaorg

Page 87: PC Hinge Materials Testing and AR Laser Diode Coating

87

Its dimensions are shown in figure 4-16

Fig 4-16 Dimensions of Convectron

Table 4-3 shows the technical specifications for this equipment

Table 4-3 Granville Phillips 375 Convectron Vacuum Pressure Controller Specs

88

424 Multimeter

For our experiment we used the Keithley 2000 Digital Multimeter as shown in figure 4-17

(a) Front Panel (b) Back Panel

Fig 4-17 Keithley Model 2000 6-12-Digit Digital Multimeter

Its technical specifications are shown in table 4-4

Table 4-4 Keithley Model 2000 6-12-Digit Digital Multimeter Specs

89

43 Experiment Procedure

1 Connecting together the equipment and the chamber

(1) We first connect the resonator to the thickness monitor and connect the other side to the

chamber

(2) We now connect the flexible tubes to the turbo pump on one side and to the chamber on the

other

(3) We need to check that tubes are tightly connected to avoid any leaks in the vacuum pumping

process which will not allow us to get to our goal of Torr As shown in figure 4-18

(4) Connect the convectron to the system as shown in figure 4-19

Fig 4-18 checking for leaks using alcohol

Fig 4-19 Convectron attached to System

90

(5) Attach the clamps of the Multimeter to the bottom of the chamber as shown in figure 4-20

(6) Place the Quartz crystal in place

(7) Close tight vacuum chamber

(8) Connect all electrical appliances to power source

Fig 4-20 Multimeter Connections

2 Starting up the System

(1) We turn on all the devices as such Check all systems are ready to function Reset all values

that might be left over from previous tests

(2) Start the thickness monitor and set all values for this experiment In our case we got to testing

the system but not actual coating So we used the simulation mode of the thickness monitor as

shown in figure 4-21

Fig 4-21 Simulation Mode

91

(3) Start the turbo pump Make sure the lid on the vacuum chamber is tightly closed

(4) Start convectron and record initial pressure

(5) Start Multimeter and record initial current

3 Coating Process

(1) If we have the deposition material inside the filament boat the power source for the high

current must be started as well

(2) Record all initial values for thickness current pressure

(3) For an ideal experiment we need a thickness of around 101 nm a pressure of Torr and

a current of 300 A

44 Results

From previous experiments we have shown that we can turn a LED into a laser by means of AR

Coating In figure 4-22 shown below we can compare the actual results of a Diode before and after AR

coating From the blue line we can see that when the diode is at a current of 15mA its light will change

from LED to laser and if we look at the red line its critical current is around 30 to 35 mA

Fig 4-22 AR Coating Comparison for Laser Diodes

This means that the light emitted is not as strong as if the diode had been coated because inside the

chamber there must be some excitation first so the reflectivity of both sides inside the diode must be high

So because of the coating in one of the sides we have opened a door and let the light come out so the

critical current is risen as such and will be higher value than that of before the coating

92

In the following figures we can see the difference between before and after coating in a material The

thickness is around 1016 nm for this material

Fig 4-23 Before Coating

Fig 4-24 After Coating

93

Chapter 5 CONCLUSIONS AND RECOMMENDATIONS

51 Conclusions

For the first part of this independent study taking into consideration the data that came out of our

research and that sent by the provider we can say

1 SUM 23 after heat treatment will unexpectedly develop cracking in the middle of the tensile

testing process and suddenly break

2 Itrsquos possible that in the process of heat treatment to the SUM 23 material the treatment was not

uniform and this will create a pre-loaded moment force on one side that pushes on the other side

of the specimen resulting in material deformation

3 In the process of attaching the strain gauges to the materials it is very easy to make errors due to

poor adhesion or sudden removal in the tensile testing process

For our second part of the independent study the following can be made

1 At the beginning of this independent study we had no idea what Bose-Einstein Condensate was

or what was its purpose After much literature we finally comprehended the basic principles to

put into practice for our research

2 Our systemrsquos basic working principles and equipmentrsquos complexity are a little difficult to grasp

but hopefully we were able to understand enough of it

3 Theoretically from relation between the power and current we can know the advantages and

disadvantages of AR Coating

4 We were able to assemble the system and run test on its functions Even though we were able to

do this there is still much more work left to do with this system

52 Recommendations

For the Tensile Testing the following can be said

1 Ask the provider to check on the process of heat treatment on the SUM 23 material and give

them the information we have gathered through our test so they can correct for the mechanical

properties found if any change is needed

2 To avoid the problem of the inaccuracy of the poor adhesion of strain gauges we can attach

multiple strain gauges to the same one specimen so as to correlate data and improve our results

For the AR Coating the following can be said

1 We need to make sure that there are no physical defects on the main body of the chamber so as to

achieve maximum efficiency in the vacuum process If there was then the vacuum will arrive to

certain point and then start to decrease

2 It would be preferable to add some sort of visual aid that will allow the user to check the inside of

the chamber without actually opening it This will help us determine at what times we should

manipulate the current to better evaporate the substrate

94

REFERENCES

[1] A L Window Strain Gauge Technology Elsevier Applied Science London and New York 2nd

Edition 1992

[2] CC Perry and HR Lissner Strain Gauge Primer McGraw-Hill Book Co Inc New York 1955

[3] James W Dally William F Riley McGraw-Hill 1978

[4] University of Colorado Boulder BEC - What is it and where did the idea come from

httpwwwcoloradoeduphysics2000becwhat_is_ithtml

[5] Ultraslow Light amp Bose-Einstein Condensates Two-way Control with Coherent Light amp Atom

Fields Harvard Hau Lab Dr Lene Vestergaard Hau Optics amp Photonics News 16 1995

[6] The Art of Taming Light Ultra-slow and Stopped Light Harvard Hau Lab Dr Lene

Vestergaard Hau Europhysics News 2004

[7] Nonlinear Optics Shocking Superfluids Harvard Hau Lab Dr Lene Vestergaard Hau Nature

Physics 2007

[8] Model P3 Strain Indicator and Recorder Instruction Manual Vishay Micro-Measurements 2005

[9] Granville-Phillips Series 375 Convectron Vacuum Gauge Controller Instruction Manual Brooks

Automation 2008

[10] Effect of Film Thickness on the Validity of the Sauerbrey Equation for Hydrated Polyelectrolyte

Films Vogt Lin Wu White 2004

[11] Quartz Crystal Microbalance Study of DNA Immobilization and Hybridization for DNA Sensor

Development Chang Zhao 2008

[12] Installation of Strain Gages with SR-4 PrecoatAdhesive Vishay Micro-Measurements 2005

[13] Strain Gauge Measurement ndash A Tutorial National Instruments 1998

[14] Correlation between Vickers Hardness Number and Yield Stress of Cold-Formed Products

Yavuz Tekkaya

[15] httpsenwikipediaorg

Page 88: PC Hinge Materials Testing and AR Laser Diode Coating

88

424 Multimeter

For our experiment we used the Keithley 2000 Digital Multimeter as shown in figure 4-17

(a) Front Panel (b) Back Panel

Fig 4-17 Keithley Model 2000 6-12-Digit Digital Multimeter

Its technical specifications are shown in table 4-4

Table 4-4 Keithley Model 2000 6-12-Digit Digital Multimeter Specs

89

43 Experiment Procedure

1 Connecting together the equipment and the chamber

(1) We first connect the resonator to the thickness monitor and connect the other side to the

chamber

(2) We now connect the flexible tubes to the turbo pump on one side and to the chamber on the

other

(3) We need to check that tubes are tightly connected to avoid any leaks in the vacuum pumping

process which will not allow us to get to our goal of Torr As shown in figure 4-18

(4) Connect the convectron to the system as shown in figure 4-19

Fig 4-18 checking for leaks using alcohol

Fig 4-19 Convectron attached to System

90

(5) Attach the clamps of the Multimeter to the bottom of the chamber as shown in figure 4-20

(6) Place the Quartz crystal in place

(7) Close tight vacuum chamber

(8) Connect all electrical appliances to power source

Fig 4-20 Multimeter Connections

2 Starting up the System

(1) We turn on all the devices as such Check all systems are ready to function Reset all values

that might be left over from previous tests

(2) Start the thickness monitor and set all values for this experiment In our case we got to testing

the system but not actual coating So we used the simulation mode of the thickness monitor as

shown in figure 4-21

Fig 4-21 Simulation Mode

91

(3) Start the turbo pump Make sure the lid on the vacuum chamber is tightly closed

(4) Start convectron and record initial pressure

(5) Start Multimeter and record initial current

3 Coating Process

(1) If we have the deposition material inside the filament boat the power source for the high

current must be started as well

(2) Record all initial values for thickness current pressure

(3) For an ideal experiment we need a thickness of around 101 nm a pressure of Torr and

a current of 300 A

44 Results

From previous experiments we have shown that we can turn a LED into a laser by means of AR

Coating In figure 4-22 shown below we can compare the actual results of a Diode before and after AR

coating From the blue line we can see that when the diode is at a current of 15mA its light will change

from LED to laser and if we look at the red line its critical current is around 30 to 35 mA

Fig 4-22 AR Coating Comparison for Laser Diodes

This means that the light emitted is not as strong as if the diode had been coated because inside the

chamber there must be some excitation first so the reflectivity of both sides inside the diode must be high

So because of the coating in one of the sides we have opened a door and let the light come out so the

critical current is risen as such and will be higher value than that of before the coating

92

In the following figures we can see the difference between before and after coating in a material The

thickness is around 1016 nm for this material

Fig 4-23 Before Coating

Fig 4-24 After Coating

93

Chapter 5 CONCLUSIONS AND RECOMMENDATIONS

51 Conclusions

For the first part of this independent study taking into consideration the data that came out of our

research and that sent by the provider we can say

1 SUM 23 after heat treatment will unexpectedly develop cracking in the middle of the tensile

testing process and suddenly break

2 Itrsquos possible that in the process of heat treatment to the SUM 23 material the treatment was not

uniform and this will create a pre-loaded moment force on one side that pushes on the other side

of the specimen resulting in material deformation

3 In the process of attaching the strain gauges to the materials it is very easy to make errors due to

poor adhesion or sudden removal in the tensile testing process

For our second part of the independent study the following can be made

1 At the beginning of this independent study we had no idea what Bose-Einstein Condensate was

or what was its purpose After much literature we finally comprehended the basic principles to

put into practice for our research

2 Our systemrsquos basic working principles and equipmentrsquos complexity are a little difficult to grasp

but hopefully we were able to understand enough of it

3 Theoretically from relation between the power and current we can know the advantages and

disadvantages of AR Coating

4 We were able to assemble the system and run test on its functions Even though we were able to

do this there is still much more work left to do with this system

52 Recommendations

For the Tensile Testing the following can be said

1 Ask the provider to check on the process of heat treatment on the SUM 23 material and give

them the information we have gathered through our test so they can correct for the mechanical

properties found if any change is needed

2 To avoid the problem of the inaccuracy of the poor adhesion of strain gauges we can attach

multiple strain gauges to the same one specimen so as to correlate data and improve our results

For the AR Coating the following can be said

1 We need to make sure that there are no physical defects on the main body of the chamber so as to

achieve maximum efficiency in the vacuum process If there was then the vacuum will arrive to

certain point and then start to decrease

2 It would be preferable to add some sort of visual aid that will allow the user to check the inside of

the chamber without actually opening it This will help us determine at what times we should

manipulate the current to better evaporate the substrate

94

REFERENCES

[1] A L Window Strain Gauge Technology Elsevier Applied Science London and New York 2nd

Edition 1992

[2] CC Perry and HR Lissner Strain Gauge Primer McGraw-Hill Book Co Inc New York 1955

[3] James W Dally William F Riley McGraw-Hill 1978

[4] University of Colorado Boulder BEC - What is it and where did the idea come from

httpwwwcoloradoeduphysics2000becwhat_is_ithtml

[5] Ultraslow Light amp Bose-Einstein Condensates Two-way Control with Coherent Light amp Atom

Fields Harvard Hau Lab Dr Lene Vestergaard Hau Optics amp Photonics News 16 1995

[6] The Art of Taming Light Ultra-slow and Stopped Light Harvard Hau Lab Dr Lene

Vestergaard Hau Europhysics News 2004

[7] Nonlinear Optics Shocking Superfluids Harvard Hau Lab Dr Lene Vestergaard Hau Nature

Physics 2007

[8] Model P3 Strain Indicator and Recorder Instruction Manual Vishay Micro-Measurements 2005

[9] Granville-Phillips Series 375 Convectron Vacuum Gauge Controller Instruction Manual Brooks

Automation 2008

[10] Effect of Film Thickness on the Validity of the Sauerbrey Equation for Hydrated Polyelectrolyte

Films Vogt Lin Wu White 2004

[11] Quartz Crystal Microbalance Study of DNA Immobilization and Hybridization for DNA Sensor

Development Chang Zhao 2008

[12] Installation of Strain Gages with SR-4 PrecoatAdhesive Vishay Micro-Measurements 2005

[13] Strain Gauge Measurement ndash A Tutorial National Instruments 1998

[14] Correlation between Vickers Hardness Number and Yield Stress of Cold-Formed Products

Yavuz Tekkaya

[15] httpsenwikipediaorg

Page 89: PC Hinge Materials Testing and AR Laser Diode Coating

89

43 Experiment Procedure

1 Connecting together the equipment and the chamber

(1) We first connect the resonator to the thickness monitor and connect the other side to the

chamber

(2) We now connect the flexible tubes to the turbo pump on one side and to the chamber on the

other

(3) We need to check that tubes are tightly connected to avoid any leaks in the vacuum pumping

process which will not allow us to get to our goal of Torr As shown in figure 4-18

(4) Connect the convectron to the system as shown in figure 4-19

Fig 4-18 checking for leaks using alcohol

Fig 4-19 Convectron attached to System

90

(5) Attach the clamps of the Multimeter to the bottom of the chamber as shown in figure 4-20

(6) Place the Quartz crystal in place

(7) Close tight vacuum chamber

(8) Connect all electrical appliances to power source

Fig 4-20 Multimeter Connections

2 Starting up the System

(1) We turn on all the devices as such Check all systems are ready to function Reset all values

that might be left over from previous tests

(2) Start the thickness monitor and set all values for this experiment In our case we got to testing

the system but not actual coating So we used the simulation mode of the thickness monitor as

shown in figure 4-21

Fig 4-21 Simulation Mode

91

(3) Start the turbo pump Make sure the lid on the vacuum chamber is tightly closed

(4) Start convectron and record initial pressure

(5) Start Multimeter and record initial current

3 Coating Process

(1) If we have the deposition material inside the filament boat the power source for the high

current must be started as well

(2) Record all initial values for thickness current pressure

(3) For an ideal experiment we need a thickness of around 101 nm a pressure of Torr and

a current of 300 A

44 Results

From previous experiments we have shown that we can turn a LED into a laser by means of AR

Coating In figure 4-22 shown below we can compare the actual results of a Diode before and after AR

coating From the blue line we can see that when the diode is at a current of 15mA its light will change

from LED to laser and if we look at the red line its critical current is around 30 to 35 mA

Fig 4-22 AR Coating Comparison for Laser Diodes

This means that the light emitted is not as strong as if the diode had been coated because inside the

chamber there must be some excitation first so the reflectivity of both sides inside the diode must be high

So because of the coating in one of the sides we have opened a door and let the light come out so the

critical current is risen as such and will be higher value than that of before the coating

92

In the following figures we can see the difference between before and after coating in a material The

thickness is around 1016 nm for this material

Fig 4-23 Before Coating

Fig 4-24 After Coating

93

Chapter 5 CONCLUSIONS AND RECOMMENDATIONS

51 Conclusions

For the first part of this independent study taking into consideration the data that came out of our

research and that sent by the provider we can say

1 SUM 23 after heat treatment will unexpectedly develop cracking in the middle of the tensile

testing process and suddenly break

2 Itrsquos possible that in the process of heat treatment to the SUM 23 material the treatment was not

uniform and this will create a pre-loaded moment force on one side that pushes on the other side

of the specimen resulting in material deformation

3 In the process of attaching the strain gauges to the materials it is very easy to make errors due to

poor adhesion or sudden removal in the tensile testing process

For our second part of the independent study the following can be made

1 At the beginning of this independent study we had no idea what Bose-Einstein Condensate was

or what was its purpose After much literature we finally comprehended the basic principles to

put into practice for our research

2 Our systemrsquos basic working principles and equipmentrsquos complexity are a little difficult to grasp

but hopefully we were able to understand enough of it

3 Theoretically from relation between the power and current we can know the advantages and

disadvantages of AR Coating

4 We were able to assemble the system and run test on its functions Even though we were able to

do this there is still much more work left to do with this system

52 Recommendations

For the Tensile Testing the following can be said

1 Ask the provider to check on the process of heat treatment on the SUM 23 material and give

them the information we have gathered through our test so they can correct for the mechanical

properties found if any change is needed

2 To avoid the problem of the inaccuracy of the poor adhesion of strain gauges we can attach

multiple strain gauges to the same one specimen so as to correlate data and improve our results

For the AR Coating the following can be said

1 We need to make sure that there are no physical defects on the main body of the chamber so as to

achieve maximum efficiency in the vacuum process If there was then the vacuum will arrive to

certain point and then start to decrease

2 It would be preferable to add some sort of visual aid that will allow the user to check the inside of

the chamber without actually opening it This will help us determine at what times we should

manipulate the current to better evaporate the substrate

94

REFERENCES

[1] A L Window Strain Gauge Technology Elsevier Applied Science London and New York 2nd

Edition 1992

[2] CC Perry and HR Lissner Strain Gauge Primer McGraw-Hill Book Co Inc New York 1955

[3] James W Dally William F Riley McGraw-Hill 1978

[4] University of Colorado Boulder BEC - What is it and where did the idea come from

httpwwwcoloradoeduphysics2000becwhat_is_ithtml

[5] Ultraslow Light amp Bose-Einstein Condensates Two-way Control with Coherent Light amp Atom

Fields Harvard Hau Lab Dr Lene Vestergaard Hau Optics amp Photonics News 16 1995

[6] The Art of Taming Light Ultra-slow and Stopped Light Harvard Hau Lab Dr Lene

Vestergaard Hau Europhysics News 2004

[7] Nonlinear Optics Shocking Superfluids Harvard Hau Lab Dr Lene Vestergaard Hau Nature

Physics 2007

[8] Model P3 Strain Indicator and Recorder Instruction Manual Vishay Micro-Measurements 2005

[9] Granville-Phillips Series 375 Convectron Vacuum Gauge Controller Instruction Manual Brooks

Automation 2008

[10] Effect of Film Thickness on the Validity of the Sauerbrey Equation for Hydrated Polyelectrolyte

Films Vogt Lin Wu White 2004

[11] Quartz Crystal Microbalance Study of DNA Immobilization and Hybridization for DNA Sensor

Development Chang Zhao 2008

[12] Installation of Strain Gages with SR-4 PrecoatAdhesive Vishay Micro-Measurements 2005

[13] Strain Gauge Measurement ndash A Tutorial National Instruments 1998

[14] Correlation between Vickers Hardness Number and Yield Stress of Cold-Formed Products

Yavuz Tekkaya

[15] httpsenwikipediaorg

Page 90: PC Hinge Materials Testing and AR Laser Diode Coating

90

(5) Attach the clamps of the Multimeter to the bottom of the chamber as shown in figure 4-20

(6) Place the Quartz crystal in place

(7) Close tight vacuum chamber

(8) Connect all electrical appliances to power source

Fig 4-20 Multimeter Connections

2 Starting up the System

(1) We turn on all the devices as such Check all systems are ready to function Reset all values

that might be left over from previous tests

(2) Start the thickness monitor and set all values for this experiment In our case we got to testing

the system but not actual coating So we used the simulation mode of the thickness monitor as

shown in figure 4-21

Fig 4-21 Simulation Mode

91

(3) Start the turbo pump Make sure the lid on the vacuum chamber is tightly closed

(4) Start convectron and record initial pressure

(5) Start Multimeter and record initial current

3 Coating Process

(1) If we have the deposition material inside the filament boat the power source for the high

current must be started as well

(2) Record all initial values for thickness current pressure

(3) For an ideal experiment we need a thickness of around 101 nm a pressure of Torr and

a current of 300 A

44 Results

From previous experiments we have shown that we can turn a LED into a laser by means of AR

Coating In figure 4-22 shown below we can compare the actual results of a Diode before and after AR

coating From the blue line we can see that when the diode is at a current of 15mA its light will change

from LED to laser and if we look at the red line its critical current is around 30 to 35 mA

Fig 4-22 AR Coating Comparison for Laser Diodes

This means that the light emitted is not as strong as if the diode had been coated because inside the

chamber there must be some excitation first so the reflectivity of both sides inside the diode must be high

So because of the coating in one of the sides we have opened a door and let the light come out so the

critical current is risen as such and will be higher value than that of before the coating

92

In the following figures we can see the difference between before and after coating in a material The

thickness is around 1016 nm for this material

Fig 4-23 Before Coating

Fig 4-24 After Coating

93

Chapter 5 CONCLUSIONS AND RECOMMENDATIONS

51 Conclusions

For the first part of this independent study taking into consideration the data that came out of our

research and that sent by the provider we can say

1 SUM 23 after heat treatment will unexpectedly develop cracking in the middle of the tensile

testing process and suddenly break

2 Itrsquos possible that in the process of heat treatment to the SUM 23 material the treatment was not

uniform and this will create a pre-loaded moment force on one side that pushes on the other side

of the specimen resulting in material deformation

3 In the process of attaching the strain gauges to the materials it is very easy to make errors due to

poor adhesion or sudden removal in the tensile testing process

For our second part of the independent study the following can be made

1 At the beginning of this independent study we had no idea what Bose-Einstein Condensate was

or what was its purpose After much literature we finally comprehended the basic principles to

put into practice for our research

2 Our systemrsquos basic working principles and equipmentrsquos complexity are a little difficult to grasp

but hopefully we were able to understand enough of it

3 Theoretically from relation between the power and current we can know the advantages and

disadvantages of AR Coating

4 We were able to assemble the system and run test on its functions Even though we were able to

do this there is still much more work left to do with this system

52 Recommendations

For the Tensile Testing the following can be said

1 Ask the provider to check on the process of heat treatment on the SUM 23 material and give

them the information we have gathered through our test so they can correct for the mechanical

properties found if any change is needed

2 To avoid the problem of the inaccuracy of the poor adhesion of strain gauges we can attach

multiple strain gauges to the same one specimen so as to correlate data and improve our results

For the AR Coating the following can be said

1 We need to make sure that there are no physical defects on the main body of the chamber so as to

achieve maximum efficiency in the vacuum process If there was then the vacuum will arrive to

certain point and then start to decrease

2 It would be preferable to add some sort of visual aid that will allow the user to check the inside of

the chamber without actually opening it This will help us determine at what times we should

manipulate the current to better evaporate the substrate

94

REFERENCES

[1] A L Window Strain Gauge Technology Elsevier Applied Science London and New York 2nd

Edition 1992

[2] CC Perry and HR Lissner Strain Gauge Primer McGraw-Hill Book Co Inc New York 1955

[3] James W Dally William F Riley McGraw-Hill 1978

[4] University of Colorado Boulder BEC - What is it and where did the idea come from

httpwwwcoloradoeduphysics2000becwhat_is_ithtml

[5] Ultraslow Light amp Bose-Einstein Condensates Two-way Control with Coherent Light amp Atom

Fields Harvard Hau Lab Dr Lene Vestergaard Hau Optics amp Photonics News 16 1995

[6] The Art of Taming Light Ultra-slow and Stopped Light Harvard Hau Lab Dr Lene

Vestergaard Hau Europhysics News 2004

[7] Nonlinear Optics Shocking Superfluids Harvard Hau Lab Dr Lene Vestergaard Hau Nature

Physics 2007

[8] Model P3 Strain Indicator and Recorder Instruction Manual Vishay Micro-Measurements 2005

[9] Granville-Phillips Series 375 Convectron Vacuum Gauge Controller Instruction Manual Brooks

Automation 2008

[10] Effect of Film Thickness on the Validity of the Sauerbrey Equation for Hydrated Polyelectrolyte

Films Vogt Lin Wu White 2004

[11] Quartz Crystal Microbalance Study of DNA Immobilization and Hybridization for DNA Sensor

Development Chang Zhao 2008

[12] Installation of Strain Gages with SR-4 PrecoatAdhesive Vishay Micro-Measurements 2005

[13] Strain Gauge Measurement ndash A Tutorial National Instruments 1998

[14] Correlation between Vickers Hardness Number and Yield Stress of Cold-Formed Products

Yavuz Tekkaya

[15] httpsenwikipediaorg

Page 91: PC Hinge Materials Testing and AR Laser Diode Coating

91

(3) Start the turbo pump Make sure the lid on the vacuum chamber is tightly closed

(4) Start convectron and record initial pressure

(5) Start Multimeter and record initial current

3 Coating Process

(1) If we have the deposition material inside the filament boat the power source for the high

current must be started as well

(2) Record all initial values for thickness current pressure

(3) For an ideal experiment we need a thickness of around 101 nm a pressure of Torr and

a current of 300 A

44 Results

From previous experiments we have shown that we can turn a LED into a laser by means of AR

Coating In figure 4-22 shown below we can compare the actual results of a Diode before and after AR

coating From the blue line we can see that when the diode is at a current of 15mA its light will change

from LED to laser and if we look at the red line its critical current is around 30 to 35 mA

Fig 4-22 AR Coating Comparison for Laser Diodes

This means that the light emitted is not as strong as if the diode had been coated because inside the

chamber there must be some excitation first so the reflectivity of both sides inside the diode must be high

So because of the coating in one of the sides we have opened a door and let the light come out so the

critical current is risen as such and will be higher value than that of before the coating

92

In the following figures we can see the difference between before and after coating in a material The

thickness is around 1016 nm for this material

Fig 4-23 Before Coating

Fig 4-24 After Coating

93

Chapter 5 CONCLUSIONS AND RECOMMENDATIONS

51 Conclusions

For the first part of this independent study taking into consideration the data that came out of our

research and that sent by the provider we can say

1 SUM 23 after heat treatment will unexpectedly develop cracking in the middle of the tensile

testing process and suddenly break

2 Itrsquos possible that in the process of heat treatment to the SUM 23 material the treatment was not

uniform and this will create a pre-loaded moment force on one side that pushes on the other side

of the specimen resulting in material deformation

3 In the process of attaching the strain gauges to the materials it is very easy to make errors due to

poor adhesion or sudden removal in the tensile testing process

For our second part of the independent study the following can be made

1 At the beginning of this independent study we had no idea what Bose-Einstein Condensate was

or what was its purpose After much literature we finally comprehended the basic principles to

put into practice for our research

2 Our systemrsquos basic working principles and equipmentrsquos complexity are a little difficult to grasp

but hopefully we were able to understand enough of it

3 Theoretically from relation between the power and current we can know the advantages and

disadvantages of AR Coating

4 We were able to assemble the system and run test on its functions Even though we were able to

do this there is still much more work left to do with this system

52 Recommendations

For the Tensile Testing the following can be said

1 Ask the provider to check on the process of heat treatment on the SUM 23 material and give

them the information we have gathered through our test so they can correct for the mechanical

properties found if any change is needed

2 To avoid the problem of the inaccuracy of the poor adhesion of strain gauges we can attach

multiple strain gauges to the same one specimen so as to correlate data and improve our results

For the AR Coating the following can be said

1 We need to make sure that there are no physical defects on the main body of the chamber so as to

achieve maximum efficiency in the vacuum process If there was then the vacuum will arrive to

certain point and then start to decrease

2 It would be preferable to add some sort of visual aid that will allow the user to check the inside of

the chamber without actually opening it This will help us determine at what times we should

manipulate the current to better evaporate the substrate

94

REFERENCES

[1] A L Window Strain Gauge Technology Elsevier Applied Science London and New York 2nd

Edition 1992

[2] CC Perry and HR Lissner Strain Gauge Primer McGraw-Hill Book Co Inc New York 1955

[3] James W Dally William F Riley McGraw-Hill 1978

[4] University of Colorado Boulder BEC - What is it and where did the idea come from

httpwwwcoloradoeduphysics2000becwhat_is_ithtml

[5] Ultraslow Light amp Bose-Einstein Condensates Two-way Control with Coherent Light amp Atom

Fields Harvard Hau Lab Dr Lene Vestergaard Hau Optics amp Photonics News 16 1995

[6] The Art of Taming Light Ultra-slow and Stopped Light Harvard Hau Lab Dr Lene

Vestergaard Hau Europhysics News 2004

[7] Nonlinear Optics Shocking Superfluids Harvard Hau Lab Dr Lene Vestergaard Hau Nature

Physics 2007

[8] Model P3 Strain Indicator and Recorder Instruction Manual Vishay Micro-Measurements 2005

[9] Granville-Phillips Series 375 Convectron Vacuum Gauge Controller Instruction Manual Brooks

Automation 2008

[10] Effect of Film Thickness on the Validity of the Sauerbrey Equation for Hydrated Polyelectrolyte

Films Vogt Lin Wu White 2004

[11] Quartz Crystal Microbalance Study of DNA Immobilization and Hybridization for DNA Sensor

Development Chang Zhao 2008

[12] Installation of Strain Gages with SR-4 PrecoatAdhesive Vishay Micro-Measurements 2005

[13] Strain Gauge Measurement ndash A Tutorial National Instruments 1998

[14] Correlation between Vickers Hardness Number and Yield Stress of Cold-Formed Products

Yavuz Tekkaya

[15] httpsenwikipediaorg

Page 92: PC Hinge Materials Testing and AR Laser Diode Coating

92

In the following figures we can see the difference between before and after coating in a material The

thickness is around 1016 nm for this material

Fig 4-23 Before Coating

Fig 4-24 After Coating

93

Chapter 5 CONCLUSIONS AND RECOMMENDATIONS

51 Conclusions

For the first part of this independent study taking into consideration the data that came out of our

research and that sent by the provider we can say

1 SUM 23 after heat treatment will unexpectedly develop cracking in the middle of the tensile

testing process and suddenly break

2 Itrsquos possible that in the process of heat treatment to the SUM 23 material the treatment was not

uniform and this will create a pre-loaded moment force on one side that pushes on the other side

of the specimen resulting in material deformation

3 In the process of attaching the strain gauges to the materials it is very easy to make errors due to

poor adhesion or sudden removal in the tensile testing process

For our second part of the independent study the following can be made

1 At the beginning of this independent study we had no idea what Bose-Einstein Condensate was

or what was its purpose After much literature we finally comprehended the basic principles to

put into practice for our research

2 Our systemrsquos basic working principles and equipmentrsquos complexity are a little difficult to grasp

but hopefully we were able to understand enough of it

3 Theoretically from relation between the power and current we can know the advantages and

disadvantages of AR Coating

4 We were able to assemble the system and run test on its functions Even though we were able to

do this there is still much more work left to do with this system

52 Recommendations

For the Tensile Testing the following can be said

1 Ask the provider to check on the process of heat treatment on the SUM 23 material and give

them the information we have gathered through our test so they can correct for the mechanical

properties found if any change is needed

2 To avoid the problem of the inaccuracy of the poor adhesion of strain gauges we can attach

multiple strain gauges to the same one specimen so as to correlate data and improve our results

For the AR Coating the following can be said

1 We need to make sure that there are no physical defects on the main body of the chamber so as to

achieve maximum efficiency in the vacuum process If there was then the vacuum will arrive to

certain point and then start to decrease

2 It would be preferable to add some sort of visual aid that will allow the user to check the inside of

the chamber without actually opening it This will help us determine at what times we should

manipulate the current to better evaporate the substrate

94

REFERENCES

[1] A L Window Strain Gauge Technology Elsevier Applied Science London and New York 2nd

Edition 1992

[2] CC Perry and HR Lissner Strain Gauge Primer McGraw-Hill Book Co Inc New York 1955

[3] James W Dally William F Riley McGraw-Hill 1978

[4] University of Colorado Boulder BEC - What is it and where did the idea come from

httpwwwcoloradoeduphysics2000becwhat_is_ithtml

[5] Ultraslow Light amp Bose-Einstein Condensates Two-way Control with Coherent Light amp Atom

Fields Harvard Hau Lab Dr Lene Vestergaard Hau Optics amp Photonics News 16 1995

[6] The Art of Taming Light Ultra-slow and Stopped Light Harvard Hau Lab Dr Lene

Vestergaard Hau Europhysics News 2004

[7] Nonlinear Optics Shocking Superfluids Harvard Hau Lab Dr Lene Vestergaard Hau Nature

Physics 2007

[8] Model P3 Strain Indicator and Recorder Instruction Manual Vishay Micro-Measurements 2005

[9] Granville-Phillips Series 375 Convectron Vacuum Gauge Controller Instruction Manual Brooks

Automation 2008

[10] Effect of Film Thickness on the Validity of the Sauerbrey Equation for Hydrated Polyelectrolyte

Films Vogt Lin Wu White 2004

[11] Quartz Crystal Microbalance Study of DNA Immobilization and Hybridization for DNA Sensor

Development Chang Zhao 2008

[12] Installation of Strain Gages with SR-4 PrecoatAdhesive Vishay Micro-Measurements 2005

[13] Strain Gauge Measurement ndash A Tutorial National Instruments 1998

[14] Correlation between Vickers Hardness Number and Yield Stress of Cold-Formed Products

Yavuz Tekkaya

[15] httpsenwikipediaorg

Page 93: PC Hinge Materials Testing and AR Laser Diode Coating

93

Chapter 5 CONCLUSIONS AND RECOMMENDATIONS

51 Conclusions

For the first part of this independent study taking into consideration the data that came out of our

research and that sent by the provider we can say

1 SUM 23 after heat treatment will unexpectedly develop cracking in the middle of the tensile

testing process and suddenly break

2 Itrsquos possible that in the process of heat treatment to the SUM 23 material the treatment was not

uniform and this will create a pre-loaded moment force on one side that pushes on the other side

of the specimen resulting in material deformation

3 In the process of attaching the strain gauges to the materials it is very easy to make errors due to

poor adhesion or sudden removal in the tensile testing process

For our second part of the independent study the following can be made

1 At the beginning of this independent study we had no idea what Bose-Einstein Condensate was

or what was its purpose After much literature we finally comprehended the basic principles to

put into practice for our research

2 Our systemrsquos basic working principles and equipmentrsquos complexity are a little difficult to grasp

but hopefully we were able to understand enough of it

3 Theoretically from relation between the power and current we can know the advantages and

disadvantages of AR Coating

4 We were able to assemble the system and run test on its functions Even though we were able to

do this there is still much more work left to do with this system

52 Recommendations

For the Tensile Testing the following can be said

1 Ask the provider to check on the process of heat treatment on the SUM 23 material and give

them the information we have gathered through our test so they can correct for the mechanical

properties found if any change is needed

2 To avoid the problem of the inaccuracy of the poor adhesion of strain gauges we can attach

multiple strain gauges to the same one specimen so as to correlate data and improve our results

For the AR Coating the following can be said

1 We need to make sure that there are no physical defects on the main body of the chamber so as to

achieve maximum efficiency in the vacuum process If there was then the vacuum will arrive to

certain point and then start to decrease

2 It would be preferable to add some sort of visual aid that will allow the user to check the inside of

the chamber without actually opening it This will help us determine at what times we should

manipulate the current to better evaporate the substrate

94

REFERENCES

[1] A L Window Strain Gauge Technology Elsevier Applied Science London and New York 2nd

Edition 1992

[2] CC Perry and HR Lissner Strain Gauge Primer McGraw-Hill Book Co Inc New York 1955

[3] James W Dally William F Riley McGraw-Hill 1978

[4] University of Colorado Boulder BEC - What is it and where did the idea come from

httpwwwcoloradoeduphysics2000becwhat_is_ithtml

[5] Ultraslow Light amp Bose-Einstein Condensates Two-way Control with Coherent Light amp Atom

Fields Harvard Hau Lab Dr Lene Vestergaard Hau Optics amp Photonics News 16 1995

[6] The Art of Taming Light Ultra-slow and Stopped Light Harvard Hau Lab Dr Lene

Vestergaard Hau Europhysics News 2004

[7] Nonlinear Optics Shocking Superfluids Harvard Hau Lab Dr Lene Vestergaard Hau Nature

Physics 2007

[8] Model P3 Strain Indicator and Recorder Instruction Manual Vishay Micro-Measurements 2005

[9] Granville-Phillips Series 375 Convectron Vacuum Gauge Controller Instruction Manual Brooks

Automation 2008

[10] Effect of Film Thickness on the Validity of the Sauerbrey Equation for Hydrated Polyelectrolyte

Films Vogt Lin Wu White 2004

[11] Quartz Crystal Microbalance Study of DNA Immobilization and Hybridization for DNA Sensor

Development Chang Zhao 2008

[12] Installation of Strain Gages with SR-4 PrecoatAdhesive Vishay Micro-Measurements 2005

[13] Strain Gauge Measurement ndash A Tutorial National Instruments 1998

[14] Correlation between Vickers Hardness Number and Yield Stress of Cold-Formed Products

Yavuz Tekkaya

[15] httpsenwikipediaorg

Page 94: PC Hinge Materials Testing and AR Laser Diode Coating

94

REFERENCES

[1] A L Window Strain Gauge Technology Elsevier Applied Science London and New York 2nd

Edition 1992

[2] CC Perry and HR Lissner Strain Gauge Primer McGraw-Hill Book Co Inc New York 1955

[3] James W Dally William F Riley McGraw-Hill 1978

[4] University of Colorado Boulder BEC - What is it and where did the idea come from

httpwwwcoloradoeduphysics2000becwhat_is_ithtml

[5] Ultraslow Light amp Bose-Einstein Condensates Two-way Control with Coherent Light amp Atom

Fields Harvard Hau Lab Dr Lene Vestergaard Hau Optics amp Photonics News 16 1995

[6] The Art of Taming Light Ultra-slow and Stopped Light Harvard Hau Lab Dr Lene

Vestergaard Hau Europhysics News 2004

[7] Nonlinear Optics Shocking Superfluids Harvard Hau Lab Dr Lene Vestergaard Hau Nature

Physics 2007

[8] Model P3 Strain Indicator and Recorder Instruction Manual Vishay Micro-Measurements 2005

[9] Granville-Phillips Series 375 Convectron Vacuum Gauge Controller Instruction Manual Brooks

Automation 2008

[10] Effect of Film Thickness on the Validity of the Sauerbrey Equation for Hydrated Polyelectrolyte

Films Vogt Lin Wu White 2004

[11] Quartz Crystal Microbalance Study of DNA Immobilization and Hybridization for DNA Sensor

Development Chang Zhao 2008

[12] Installation of Strain Gages with SR-4 PrecoatAdhesive Vishay Micro-Measurements 2005

[13] Strain Gauge Measurement ndash A Tutorial National Instruments 1998

[14] Correlation between Vickers Hardness Number and Yield Stress of Cold-Formed Products

Yavuz Tekkaya

[15] httpsenwikipediaorg