Diffractive Optical Elements and Micro-Optics · 2018. 1. 30. · Seoul National University OEQELab Diffractive Optics Technology Provides new degrees of freedom for the design and

$Page 1: Diffractive Optical Elements and Micro-Optics · 2018. 1. 30. · Seoul National University OEQELab Diffractive Optics Technology Provides new degrees of freedom for the design and$
Diffractive Optical Elements andMicro-Optics

이 병 호

서울대 전기공학부

[email protected]

OEQELabSeoul National University

Diffraction

Sommerfeld:

“any deviation of light rays from

rectilinear paths which cannot be

interpreted as reflection or refraction”


Examples of Fraunhofer Diffraction

Fraunhofer diffraction from a

rectangular aperture. The central lobe

of the pattern has half-angular widths

yyxx DD / and /

The Fraunhofer diffraction

pattern from a circular aperture

produces the Airy pattern with

the radius of the central disk

subtending an angle D/22.1


Fresnel Diffraction by Square Aperture

(b) Diffraction pattern at four axial positions

marked by the arrows in (a) and

corresponding to the Fresnel numbers NF=10,

1, 0.5, and 0.1. The shaded area represents

the geometrical shadow of the slit. The

dashed lines at represent the

width of the Fraunhofer pattern in the far

field. Where the dashed lines coincide with

the edges of the geometrical shadow, the

Fresnel number NF=

dDx /

.50/2

.da

Fresnel Diffraction from a slit

of width D = 2a. (a) Shaded

area is the geometrical shadow

of the aperture. The dashed

line is the width of the

Fraunhofer diffracted beam.


Diffractive Optics Technology

Provides new degrees of freedom for the design and

optimization of optical systems

FeaturesLarge aperture, lightweight optical elements

Aberration correction and achromatization

Eliminates need for exotic materials

Increase in performance over conventional systems

System weight, complexity, and cost can be reduced significantly

Applications


Fabrication of a Surface-Relief Master

Lithography – Optical & E-Beam

Staircase blaze profiles

Binary optics – multiple e-beam masks

Continuous blaze profiles

Gray-scale masks

Variable e-beam exposure

Single-Point Diamond Turning

Linear and spherical blaze profiles

Single-Point Laser Pattern Generation

Vary exposure to shape blaze profile

X-Y and R-theta scan geometries


Diffractive Optical Element (DOE) (I)

N

Nq

q

qq

2

2sinc

2sinc

2sinc

0

2

02

2


Diffractive Optical Element (DOE) (II)


Advances in Single-Point Diamond Turning

1989

Diffraction Efficiency

: 85% - 90%

1989


: 85% - 90%

1999


: 97% - 99%

G. M. Morris


Laser Pattern Generator

G. M. Morris


Micro-Optics Manufacturing Technique using Reactive Ion Etching


Microlens (I)


Microlens (II)


Microlens (III)


Wavefront Sensing


- Micro-sized convex lens array

- Optical switching device for optical communication system

- Focusing device for optical data storage

- 3-D display component for super-multi view

- Various application for photonic devices

[3D-image system]

Microlens Array


- Patterned electrode type

- Surface-relief structure type

- FLC microlens using surface relief

- Input polarization dependence

• In practical applications,

Independence of Input Polarization is needed !!

Liquid Crystal Microlenses


Lord Rayleigh

“…If it were possible to introduce at every part of the aperture of the grating an arbitrary retardation, all the light might be concentrated in any desired spectrum. By supposing the retardation to vary uniformly and continuously we fall upon the case of an ordinary prism; but there is then no diffraction spectrum in the usual sense. To obtain such it would be necessary that the retardation should gradually alter by a wave-length in passing over any element of the grating, and then fall back to its previous value, thus springing suddenly over a wave-length. It is not likely that such a result will ever be fully attained in practice; but the case is worth stating, in order to show that there is no theoretical limit to the concentration of light of assigned wave-length in one spectrum…”

Encylopaedia Britannica, 9th ed., Vol. 24, “Wave Theory

of Light” (New York, Charles Schribner’s Sons, 1888), p. 437

J. W. Strutt

(1842-1919)

G. M. Morris

Never say ‘Never’!


Tracor Flat-Panel ANVIS E-HUD*


Application Example

G. M. Morris


Micropattering Using DOE and Femtosecond Laser

Y. Kuroiwa et al., Optics Express, vol. 12, no. 9, pp. 1908-1915, 2004.


Theoretical study on design and analysis of DOEs

DOE design problem

Basic layout of paraxial beam shaping system

2 2 2 2 1 1 1 1 1 1, , , , , ,F x y h x y x y W x y dx dy

1 1 1 1 1 1, , exp ,W x y A x y j x y

Surface relief structure

of DOE

Input field Output field

1 1,x y

Diffraction

image 2 2,F x y


Nonlinear optimization methods for DOE design

Hybrid method

2

2

1 1 2 2Find , for minimizing ,

L

x y E I F x y

Minimization scheme

Iterative methods

Iterative Fourier transform algorithm (IFTA)

Nonlinear conjugate gradient method (NCGM)

Stochastic methods

Simulated annealing method (SA)

Genetic algorithm (GA)

SA or GA + IFTA or NCGM


Iterative Fourier transform algorithm (IFTA) for DOE design

Soft constraint

Amplitude and phase

freedoms

Hard constraint

Functional relationship

between phase and

amplitude modulations

expn n n

W A j

Input plane

Diffraction imagePhase

hologram

Forward Fresnel

transform

Inverse Fresnel

transform

Output plane

IFTA

Existence of the analytic expression of the inverse Fresnel transform is the key of IFTA.


Regularization technique for obtaining the optimal trade-off

between diffraction efficiency and uniformity

H. Kim, B. Yang, and B. Lee, Journal of the Optical Society of America A, vol. 21, p. 2353, 2004.

H. Kim and B. Lee, Japanese Journal of Applied Physics, vol. 43, no. 6A, p. L702, 2004.

76 78 80 82 84 86 88 90 920

0.05

0.1

0.15

0.2

0.25

0.3

0.35

0.4

0.45

Un

ifo

rm

ity

Diffraction efficiency (%)

Proposed

IFTAConventional

IFTA

76 78 80 82 84 86 88 90 920

0.05

0.1

0.15

0.2

0.25

0.3

0.35

0.4

0.45

Un

ifo

rm

ity


76 78 80 82 84 86 88 90 920

0.05

0.1

0.15

0.2

0.25

0.3

0.35

0.4

0.45

Un

ifo

rm

ity


Proposed

IFTAConventional

IFTA

Proposed

IFTAConventional

IFTA

Proposed

IFTAConventional

IFTA

IFTA scheme with Tikhonov regularization scheme

(adaptive regularization parameter distribution)

Diffraction efficiency=84.7%

Uniformity=0.0365

(arb

. u

nit

s)(a

rb. u

nit

s)


Uniformity=0.0365

(arb

. u

nit

s)(a

rb. u

nit

s)


Uniformity=0.0746

(arb

. u

nit

s)(a

rb. u

nit

s)


Uniformity=0.0746

(arb

. u

nit

s)(a

rb. u

nit

s)

Proposed design Conventional design


Hybrid scheme of IFTA and GA for optimal IFTA convergence

Micro genetic algorithm + IFTA

Micro genetic algorithm finds the

optimal relaxation parameter vector of

the imbedded IFTA scheme.

IFTA shows non-monotonic optimal

convergence.

Micro genetic algorithm

for ( , )x y S

for ( , )x y Sn

F

01

0

0

2

, ,2exp 1 tan

,

exp

nnn n n n

n D n n

F x y F x yF j F

F x y

F i

nF for ( , )x y S

for ( , )x y Sn

F

01

0

0

2

, ,2exp 1 tan

,

exp

nnn n n n

n D n n

F x y F x yF j F

F x y

F i

nF

nF

01

0

0

2

, ,2exp 1 tan

,

exp

nnn n n n

n D n n

F x y F x yF j F

F x y

F i

nF

01

0

0

2

, ,2exp 1 tan

,

exp

nnn n n n

n D n n

F x y F x yF j F

F x y

F i

nF

IFTA

H. Kim and B. Lee, Optics Letters, vol. 30, p. 296, 2005.


0 250 500 750 1000 1250 15000.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

0.9

1

Un

ifo

rm

ity

Iteration number

0 50 100 150 2000.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

0.9

11

0.8

0.6

0.4

0.2

0 50 100 150 200

0 250 500 750 1000 1250 15000.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

0.9

1

Un

ifo

rm

ity

Iteration number

0 50 100 150 2000.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

0.9

11

0.8

0.6

0.4

0.2

0 50 100 150 2000 50 100 150 2000.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

0.9

11

0.8

0.6

0.4

0.2

0 50 100 150 200

0 250 500 750 1000 1250 150050

55

60

65

70

75

80

85

90

Dif

fra

cti

on

eff

icie

ncy

Iteration number

0 50 100 150 20050

55

60

65

70

75

80

85

9090

80

70

60

50

0 50 100 150 2000 50 100 150 200

50

55

60

65

70

75

80

85

9090

80

70

60

50

0 50 100 150 200

0 250 500 750 1000 1250 150050

55

60

65

70

75

80

85

90

Dif

fra

cti

on

eff

icie

ncy

Iteration number

0 50 100 150 20050

55

60

65

70

75

80

85

9090

80

70

60

50

0 50 100 150 2000 50 100 150 200

50

55

60

65

70

75

80

85

9090

80

70

60

50

0 50 100 150 200

x (sampling index) y (sampling index)

Inte

nsi

ty (

a.u

.)


Uniformity=0.113


Inte

nsi

ty (

a.u

.)


Inte

nsi

ty (

a.u

.)


Inte

nsi

ty (

a.u

.)


Uniformity=0.113

Proposed design


Inte

nsi

ty (

a.u

.)


Uniformity=0.401


Inte

nsi

ty (

a.u

.)x (sam

pling index) y (sampling index)

Inte

nsi

ty (

a.u

.)x (sam

pling index) y (sampling index)

Inte

nsi

ty (

a.u

.)


Uniformity=0.401

Conventional design

Non-monotonic optimal convergence of IFTA


Speckle reducing problem in DOE design

Phase profile of conventional DOEObtained diffraction image

Optical vortices appear in the diffraction image generated by a conventional DOE


Cross-section of input beam

Obtained diffraction image Phase profile of the proposed DOE

H. Kim and B. Lee, Japanese Journal of Applied Physics, vol. 43, no. 12A, p. L1530, 2004.

Boundary modulated DOE design

Optical vortices are eliminated in the diffraction image generated by the proposed

boundary modulated DOE


Accurate modeling of the transmittance functions of DOEs

t

Incident plane wave

Transmitted wave

Internal reflections

In

IIn

InBack scattered wave

t

Incident plane wave

Transmitted wave

Internal reflections

In

IIn

InBack scattered wave

H. Kim and B. Lee, Optical Engineering, vol. 43, no. 11, p. 2671, 2004.

The transmittance function of a multilevel DOE is calculated considering internal

multiple reflections inside the DOE structure.


Ph

ase

err

or

(deg.)

X direction position index

Y direction position index

Ph

ase

err

or

(deg.)



Ph

ase

err

or

(deg.)



Norm

ali

zed

thic

kness



Norm

ali

zed

thic

kness



Norm

ali

zed

thic

kness



No

rmali

zed

thic

kn

ess



No

rmali

zed

thic

kn

ess



No

rmali

zed

thic

kn

ess



No

rmali

zed

thic

kn

ess



No

rmali

zed

thic

kn

ess



No

rmali

zed

thic

kn

ess



Phase

err

or

(deg.)


Y d

irectio

n p

ositio

n in

dex

Phase

err

or

(deg.)


Y d

irectio

n p

ositio

n in

dex

Phase

err

or

(deg.)


Y d

irectio

n p

ositio

n in

dex

Conventional design

Normal

incidence

Oblique

incidence

Phase error

Proposed design without phase errors

Refractive index=3.4

Comparison of the proposed transmittance function with

the conventional transmittance function


Laser display system and speckle problem

The speckle patterns impair the image quality (strong deblurring of the color edges)

Low transmission efficiency and deterioration of the laser beam quality

Coherence degradation of the light source, diffuser, digital image processing of signals

R

B

G M

M

MLaser

ModulatorDichroic

Mirror

Projection

Scanning

system

Screen

Resolution

Spot

ObserversSync. signals

Surface

height

fluctuation

Uncorrelated

speckle =c /

d = 2.2mm

f# = 3.5 ~ 5.6 1/ 2

det _( / ) 2 /( # )proj pixel pupil size eyeC h d f

Speckle reduction for laser display

OEQELabSeoul National University IEEE LEOS ’99, pp.354-355.

3597.20.009All vibrated components & lens arrays

089.50.034Vibrated projection screen

585.10.048Vibrated diffractive diffuser

2082.40.057Vibrated fiber

2018.90.262Fiber, 2m

144.30.309Refractive lens array(68)

53.40.312Stationary diffractive diffuser

Insertion loss(%)Speckle reduction(%)Speckle contrastComponent

Speckle configuration

- Speckle contrast ratio: “Severe” speckle is associated with contrast measurements of C > 0.30

Comparison of speckle degradation methods

i

ii

I

IIC

22 where, <Ii> : intensity of the ith pixel of a CCD

: standard deviation, : mean value

Speckle reduction for laser display


Nd:YAG, DPSS

(500mW, 532nm)

VC44 CCD

(756 581)

Laser

Image

Processor

DOE

L1

L2 L3

L4

L5

Polygon scanner

Screen

f1 f2Rotation

2

0

phase

(ra

d)

0

1

2

3

4

5

100 200 300 400 500

50

100

150

200

250

300

350

400

450

500

2

0

phase

(ra

d)

2

0

phase

(ra

d)

0

1

2

3

4

5

100 200 300 400 500

50

100

150

200

250

300

350

400

450

5000

1

2

3

4

5

100 200 300 400 500

50

100

150

200

250

300

350

400

450

500

Speckle reduction using DOEs


Speckle pattern and its histogram of Nd:YAG laser source, (static DOE, and rotating DOE (5rps).

CRLaser = 0.5126 CRDOE, static = 0.2729 CRDOE, rotation = 0.2388

Speckle reduction using DOEs


Theoretical studies on design and analysis of DOEs

DOE design for non-invertible Fresnel diffraction integral

IFTA is not applicable for the design of DOEs for making diffraction images on an

arbitrarily curved surface.



Nonlinear conjugate gradient method

2 2

2

expN N

mn n n m

m n

E m G A j I

Φ

Objective functionmI

m

Target image

Weight distribution

Flow chart of NCGM

0 0E d Φ

Bracketing algorithm

Golden section line search

Fletcher-Reeves formula

1k k k k Φ Φ d

k 1min ;

k kE

Φfor

1 1k k k kE

d Φ d

2

1 2

1

k

k

k

E

E

Φ

Φ

1k k



Design example

2 2for ,x y

Target image Curved output surface (defocus surface)

7

1 2 2

0

3

2 7 / 2 2 2h hh

h

h

A c c

Amplitude function as a function of phase

0 2A A 0 2A A

y (sampling point) x (sampling point)

Inte

nsi

ty

(no

rm

ali

zed

)y (sam

pling point) x (sampling point)

Inte

nsi

ty

(no

rm

ali

zed

)y (sam

pling point) x (sampling point)

,s x y


,s x y



Diffraction simulation

Field amplitude distribution

on the curved output surface

Field amplitude distribution

on the flat plane (z2=0)


Inte

nsi

ty (

a.u

.)


Inte

nsi

ty (

a.u

.)


Inte

nsi

ty (

a.u

.)


Inte

nsi

ty (

a.u

.)

y (sampling point)x (sampling point)

Inte

nsi

ty (

a.u

.)

y (sampling point)x (sampling point)

Inte

nsi

ty (

a.u

.)


Inte

nsi

ty (

a.u

.)


Inte

nsi

ty (

a.u

.)

DOE for curved surface

1

2

3

4

5

6

1

2

3

4

5

6

DOE for flat surface



Electromagnetic analysis on subwavelength scale DOEs

Fourier expansion of binary subwavelength scale grating

, exp 2mn

m n x y

m nx y j x y

T T

pq

pqf

x

y

L N

L N

,p q

2 2

2 1

1 1

,

1[ ,

sinc exp ]

M M

mn mn pq

p qx y

pq pq mn pq

k x y

D p q n n fT T

m nkf j k f L H k

T T

Binary surface relief structure on a subwavelength scale can modulate both phase and

amplitude of the incident optical field.


wavelength

wav

elen

gth

per

mit

tiv

ity

wavelength

wav

elen

gth

wavelength

wav

elen

gth

per

mit

tiv

ity

Phas

e (r

ad)

wavelength wavelength

Phas

e (r

ad)

Phas

e (r

ad)

wavelength wavelength


wavelength

wavelength

perm

itti

vit

y

wavelength

wavelength

perm

itti

vit

y

wavelength

wavele

ngth

Ph

ase

(ra

d)

wavelength

wavele

ngth

Ph

ase

(ra

d)

Rigorous coupled wave analysis (RCWA)

xE

wavelength

wavelength

xE

wavelength

wavelength

xExE

wavelength

wavelength

xE

wavelength

wavelength

xE

wavelength

wavelength

xExE

wavelength

wavelength

The binary subwavelength scale gratings can modulate both phase and amplitude of

the incident optical field.


fill factor

tilt

an

gle

(ra

d)

ph

ase

(ra

d)

fill factor

tilt

an

gle

(ra

d)

ph

ase

(ra

d)

fill factor

tra

nsm

issi

on

coef

fici

ent

tilt angle (rad)

fill factor

tra

nsm

issi

on

coef

fici

ent

tilt angle (rad)

Phase modulation

Amplitude modulation


Dynamic range of phase and amplitude modulation for fill

factor and tilt angle

0 1 2 3 4 5 60.2

0.3

0.4

0.5

0.6

0.7

0.8

0.9

1

max trans.

min trans.

phase (rad)

tra

nsm

issi

on

co

eff

icie

nt

0 1 2 3 4 5 60.2

0.3

0.4

0.5

0.6

0.7

0.8

0.9

1

max trans.

min trans.

0 1 2 3 4 5 60.2

0.3

0.4

0.5

0.6

0.7

0.8

0.9

1

max trans.

min trans.

phase (rad)

tra

nsm

issi

on

co

eff

icie

nt

S

Dynamic range map in phase and amplitude

modulation for fill factor and tilt angle


Experimental study on dynamic beam shaping with LC SLM

Beam shaping with a dynamic liquid crystal spatial light

modulator

LC SLM beam shaping system (phase hologram)

- Electrical controllability

- Real-time dynamic beam shaping

System layout


Phase and amplitude modulations of the LC SLM

Dynamic characteristics of LC SLM

Nonlinear variation of the phase and amplitude of the SLM

Phase and amplitude compensation

0

0.03

0.06

0.09

0.12

0 50 100 150 200 250Gray level

Am

pli

tud

e m

od

ula

tion

(a.u

.)

0

0.03

0.06

0.09

0.12

0 50 100 150 200 250Gray level

Am

pli

tud

e m

od

ula

tion

(a.u

.)

0 50 100 150 200 2500

0.2

0.4

0.6

0.8

1

0

0.5

1

1.5

2

0 50 100 150 200 250Gray level

Ph

ase m

od

ula

tion

(πu

nit

rad.)

0

0.5

1

1.5

2

0 50 100 150 200 250Gray level

Ph

ase m

od

ula

tion

(πu

nit

rad.)

These relationships must be taken into account in the phase hologram design.



Laser

Polarizer Analyzer

CCD

LCD SLMBeam expander

1d 2df

Optical system

Laser

Polarizer Analyzer

CCD


1d 2df

LaserLaser

Polarizer Analyzer

CCD


1d 2df

Optical system

Capturingholographic

image

Recording phase

hologram

Genetic feedback tuning loop

Laser

Polarizer Analyzer

CCD


1d 2df

Optical system

Laser

Polarizer Analyzer

CCD


1d 2df

LaserLaser

Polarizer Analyzer

CCD


1d 2df

Optical system

Capturingholographic

image

Recording phase

hologram

Genetic feedback tuning loop

DPSS Nd:YAG (532nm)

Experimental setup with real-time adaptive genetic feedback tuning loop

Beam shaping system with the genetic feedback tuning

loop(GFTL)

J. Hahn, H. Kim, K. Choi, and B. Lee, Applied Optics, vol. 45, no. 5. p. 915-924, 2006.



Control panel for adaptive beam

shaping

DOE phaseprofile

A. Diffraction image

B. Targetimage

Difference image between A and B

Phase modulationcurve

Coefficients of Zernike polynomial

Cost valueof the elite

Zernike polynomials

Create the initial population

0| 0,1, ,

iP x i m

:elite xMutation

maxk

F x F P

k kP Pmutation

ˆ maxk

F x F P

:New elite x

ˆmax ,F x F x F x

maxk k

:Elite x

Yes

No

Reorganize the population 1|

k i i iP x f f

, |

0, , 1, , ,

i j j

k

x x x xP

i h j h m

sorting

1k k

0k

System control panel & implemented genetic algorithm

Genetic algorithm



Zernike polynomial model of compensating phase profile

0

00 0

2 1 1 1 1

, ,

1cos sin ,

2

n nm m

n n nm n nm n

n n m n m

x y

A A R A R m A R m

2 2

c cx x y y

1tan c

c

y y

x x

mnA coefficients to be optimized

m

nR Zernike polynomial

Aberration compensation in the GFTL beam shaping system


The GFTL is effective in compensating the aberration of the internal optics

of the beam shaping system.


Compensation of aberrated (tilted) optics with GFTL

LC

SLM

Laser

Polarizer AnalyzerBeam Expander

Iris

10o 10o

f = 500mm

d1 = 500mm

d2 = 490mm(defocus)

tilt angle of lens = +10o

tilt angle of CCD = -10o

Distorted diffraction

Image in the tilted

optics

Diffraction image

obtained in

the aligned optics

Experimental setup



Target diffraction imageEvolution of

the diffraction image

The diffraction image evolves to the target diffraction image, overcoming the internal

aberration of the beam shaping system.


Experimental results – dynamic aberration compensation

Resulting Zernike

phase profile


Comparison of another diffraction image obtained by the compensated system in

the previous page and the aberrated system

Aberrated diffraction image Compensated diffraction image

Experimental results – dynamic aberration compensation



Applications of computer generated DOEs

2-D perfect shuffle network system

1

EA

5

8

D4

63

CG

7

FB

H

2

.

.

.

N

N

Output ports

or Detector

Fourier

transform lens

Light

source

Reconstruction

planeLC-SLM

Collimating

lens

Reconfigurable 2-D PSNS

A2

1B

C6

D

37

HG 4

FE

5

8

Dynamic

Hologram input

1A

2B

8H

G

DE

F5 6

C4

7

3

13

24

HF

E

8A

BC D

76

G

5

1E

A5

8D

4

63

CG 7

FB

H

2

Reconfigurable 2D optical perfect shuffle network system



Experimental results

K. Choi and B. Lee, IEEE Photon. Technol. Lett., vol. 17, no. 3, p. 687, 2005.

SLM: Holoeye Holo2002 832x624 (512x512) pixels, ~60 Hz maximum frame rate,

32um x 32 um pixel size


Laser tweezer setup and results

w = 532nm (Nd:YAG, 5W), Dielectric spheres (silica,8.6m & polystylene, 6.7m)

Dynamic computer-generated hologram loaded on 2D spatial light modulator

Analyzer

CC

D

Monitor

F.T. lens(Acromat) Phase-SLM

DynamicCGH input

Modulated signals

Beam expander Wave

plate

MicroscopeCSB-HP5

Objective lens

Mirror

GreenLD

(532 nm)

Dichroicmirror

Diagram showing the optical setup of laser tweezers with

dynamically controlled holograms of the laser beamScattering patterns



Holographic optical tweezer


AnalyzerProjection

lens

Observer

Color CCD

SF3

BE3

P3

SF2

BE2

P2

Nd:YAG Laser

(532 nm)

M2

BS1

Phase-SLM module

BS2

BS3

SF1

BE1

P1

HeNe

Laser

(632.8 nm)

M1

Monitor

Nd:YAG Laser

(473 nm)

F.T. lens

(Acromat) CGH input

(RGB)

LD

LCD

Modulated signals


K. Choi, H. Kim, and B. Lee, Optics Express, vol. 12, no. 11, p. 2454, 2004.K. Choi, H. Kim, and B. Lee, Optics Express, vol. 12, no. 21, p. 5229, 2004.

Full-color autostereoscopic 3D display system using color-

dispersion compensated computer generated (CG) DOEs

SLM: PPM X8267

(Hamamatsu)

1024x768 pixels

25 um pixel size



Simulation of full-color auto-stereoscopic video using

CG-DOEs


Stereo input video

Reconstructed stereo video (experiment)

Reconstructed stereo video (simulation)Full-color autostereoscopic 3D display demo

system

13


Demonstration system for full-color auto-stereoscopic 3D

display using CG-DOEs


Schematic diagram of our multi-view

auto-stereoscopic 3D display system

Color-separation

& CDC holograms F.T lens

(Acromat)

Auto-streoscopic

multi-view full-color

3D image reconstruction

ObserversMultipexed

holograms

Stereo

input

image

Combine

CDC-

CGHs

input

control

RL

RR

GL

GR

BL

BR

CDC

multiple directional

Holograms (right)

Multiplexing

CDC

multiple directional

Holograms (left)


Multi-view stereoscopic display system using CG-DOEs


Analyzer

Projection

lens

module

Observers

PC controller

& monitor

F.T. lens

(Acromat)

Phase-SLM

Multiplexed

CDC CGH

inputGreen

LD

(532 nm)

Mirror

BS1

Blue

LD

(473 nm)

BE3 BE2

BS2

BS3

Color

CCD

BE1

Red

LD

(635.nm)

M1


Schematic of multi-view stereoscopic display system using

CG-DOEs


Plane wave or backlight source

CalculatedCGHs

SLM control

CCD

Real 3D object

CGH

calculation

using IFTA

Captured/computer-generated

elemental image

Input lensarrays

Elemental-lensarray

Relay optics


Full-parallax 3D display system using CG-DOEs and integral

imaging

K. Choi, J. Kim, Y. Lim, and B. Lee, Optics Express, vol. 13, no. 26, pp. 10494-10502, 2005.


Projection

lens

module

Diffusing

screen &

Lens array

Acromatic

lens SLM

Beam

splitter

Polarizer

Analyzer

Beam

combiner

Red LD

(635 nm) Green LD

(532 nm)

To CCD

Mirror

Filter

Beam

expander

Beam

expander

Analyzer

Projection

lens module

PC controller

& monitor

F.T. lens

(Acromat)

Phase-SLM

Multiplexed

CDC-SPH

input Green

LD

(532 nm)

BE2

BS2

BS3

Color

CCD

BE1

Red

LD

(635.nm)

M1

Diffuser

Integral lens

array

M2


Full-parallax 3D display system using CGHs and integral

imaging


Elemental image input

Reconstructed video

(simulation)

Reconstructed video

(experimental result)




Brightness Enhancement Films

Our surface relief structure for brightness enhancement films (BEFs)

Periodic pyramidal prism sheet

Our surface relief structure for

substitution of prism sheet

1d2d

Height

TFT-LCD backlight module structure

Light source

( CCFL )

Prism sheet

Diffuser

Light guide plate

Reflector

Backlight

Frame assembly


Ray Tracing Simulation

, cosI B

Radiant intensity of point source:

-0.5

0

0.5 -0.5

0

0.5

0

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

0.9

1

Prism sheet

Radiant intensity profile of uniform input , height of 0.7

Measuring point

• Uniformly distributed point sources

• Considering multiple ray scattering process on

the surface

• Infinite size of prism sheet

• Periodic structure


Classification of Rays Concentrated onto the Condensing Area by the Spatial Ray Directions

0

0.1

0.2

0.3

0.4

0.5

0.6

0.7

20 40 60 80 100 120 140

10

20

30

40

50

60

70

80

90

height = 0.3

0

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

20 40 60 80 100 120 140

10

20

30

40

50

60

70

80

90

height = 0.4

0

0.1

0.2

0.3

0.4

0.5

0.6

0.7

20 40 60 80 100 120 140

10

20

30

40

50

60

70

80

90

height = 0.5

0

0.1

0.2

0.3

0.4

0.5

0.6

0.7

20 40 60 80 100 120 140

10

20

30

40

50

60

70

80

90

height = 0.6

0

0.05

0.1

0.15

0.2

0.25

0.3

0.35

20 40 60 80 100 120 140

10

20

30

40

50

60

70

80

90

height = 0.7

0

0.05

0.1

0.15

0.2

0.25

0.3

20 40 60 80 100 120 140

10

20

30

40

50

60

70

80

90

height = 0.8

0

0.05

0.1

0.15

0.2

0.25

20 40 60 80 100 120 140

10

20

30

40

50

60

70

80

90

height = 0.9

0

0.05

0.1

0.15

0.2

0.25

20 40 60 80 100 120 140

10

20

30

40

50

60

70

80

90

height = 1.0

B. Lee, H. Kim, and K. Choi, "Design and analysis of gratings and diffractive optical elements for displays," Proc. The 5th Pacific Rim Conference on Lasers and Electro-Optics (CLEO/PR), Taipei, Taiwan, vol. 2, p. 643, CD file Paper TH4E-(17)-2, Dec. 2003 (Invited paper).


Engineered DiffusersTM

- Random Microlens Screen Design Concept

Random Microlens Array Photoresist Master

* Figures are from the talk delivered by G. M. Morris in 2003.


Full-color laser display system using DOEs

Full-Color Laser Display System

Red image Green image Blue image

R hologram G hologram B hologram

Synthetic of phase holograms

Reconstruction of color image

Full color image Color optimization

Cmin= | (R) -N(R)|

+ | (G)-N(G)| +| (B) -N(B)|

N(R):N(G):N(B)

= (166 : 135 :128)

= (262 : 213 : 202)

= (380 : 309 : 293)

(R) = 632.8nm, (G) = 514.5nm, (B) = 488nm


Principles of CDC-SPHs

Principles of chromatic-dispersion-compensated synthetic phase holograms(SPHs)

Stereo viewing conditions

Observer's viewing distance (300mm), eye separation (65mm), pupil size (3mm).

Three illumination sources: 635nm (red), 532nm (green), and 473nm (blue)

The size of designed CDC-SPHs is 256X256 and minimum pixel size of SLM is about 32mm

Each size of reconstructed color image is about 6mm(R), 5mm(G), and 4.4mm(B)

Real-time PC-SPHs

input

(~ 30 frames/sec)


Experimental Setup and Results

Experimental setup and results for the full-color CDC-SPHs

Dynamic full-color holographic display system using only a SLM and three sources

The lens of the system must be an aberration-corrected(chromatic, spherical).

Analyzer

Projection

lens

module

Observer

Color CCD

Monitor

F.T. lens(Acromat)

Phase-SLM

CDC-SPHs input

(RGB)

Modulated signals

SF3

BE3

P3

SF2

BE2

P2

GreenLD

(532 nm)

M2

BS1 BS2 BS3

SF1

BE1 P1

RedLD

(635.nm)

M1

Blue LD

(473 nm)


DOE Trend

Period Driving force Applications

Late 1980’s

~early 1990’s

The optical computing Back-plane optical interconnections

Free-space 2D multi-plane optical interconnection

architectures for 2D or 3D parallel optoelectronic processors

2D image processing applications

Harmonic component filters

None of these optical functions are implemented in

commercial architectures

Mid 1990’s~ The optical storage Diffractive optical pick up units

High NA diffractive lenses for magneto optical drives

Beam splitting gratings for CD tracking

DVD/CD lenses

Late 1990’s The optical telecom High order ruled gratings for WDM/DWDM Mux/Demux

Micro Fresnel lenses for fiber couplers

Diffractive microlens arrays for 10Gb/s


Continued..

Period Driving force Applications

Current Anti-counterfeiting market

Imaging applications

Ophthalmic industry

Photographic industry

Personal digital accessory and

consumer electronics technology

Optical metrology

Entertainment business-

packaging industry

Diffractive optical variable image devices

ID cards

Virtual keyboard projector

Laser radar motion sensing devices

Hybrid zoom lens objectives using pairs of

sandwiched diffractives

Subwavelength diffractive elements

polarization beam splitting

anti-reflection surfaces for solar cells, polarization

sensitive and high resolution

Resonance filtering applications

Laser pointer pattern generator

Future Biotechnology

High resolution lithography

Fluorescence measurement

Optimum reticle illumination

Complex phase shift mask


Conclusion-DOE

Concepts of DOE and some applications

Theory and design issues of DOEs are introduced and discussed.

Scheduling relaxation parameters of IFTA

Modulation of both phase and amplitude of optical wave by using binary

surface relief structure on a sub-wavelength scale

Boundary-modulated DOE optimization

Display application examples using DOEs are presented.

Light condensing characteristics of a periodic pyramidal prism sheet

Full-color laser display system using DOEs

Directional DOEs for LCD-based stereoscopic systems

Documents

Diffractive Optical Elements and Micro-Optics · 2018. 1. 30. · Seoul National University OEQELab Diffractive Optics Technology Provides new degrees of freedom for the design and