Upload
jorge-eduardo-sanchez
View
24
Download
4
Embed Size (px)
DESCRIPTION
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.
Citation preview
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
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
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
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
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
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
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
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
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
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
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
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
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
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
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
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
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
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
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
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
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
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
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
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
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
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
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
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
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
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
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
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
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
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
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
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
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
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
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
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
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
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
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
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
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
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
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
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
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
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
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
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
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
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
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
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
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
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
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
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
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
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
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
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
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
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
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
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
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
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
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
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
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
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
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
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
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
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
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
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
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
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
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
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
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
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
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
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
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
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
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
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
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
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