diffractive optical elements and micro-opticsocw.snu.ac.kr/sites/default/files/note/1647.pdf ·...
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OEQELabSeoul National University
Diffraction
Sommerfeld:
“any deviation of light rays from
rectilinear paths which cannot be
interpreted as reflection or refraction”
OEQELabSeoul National University
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
OEQELabSeoul National University
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.
OEQELabSeoul National University
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
OEQELabSeoul National University
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
OEQELabSeoul National University
Diffractive Optical Element (DOE) (I)
N
Nq
q
2
2sinc
2sinc
2sinc
0
2
02
2
OEQELabSeoul National University
Diffractive Optical Element (DOE) (II)
OEQELabSeoul National University
Advances in Single-Point Diamond Turning
1989
Diffraction Efficiency
: 85% - 90%
1989
Diffraction Efficiency
: 85% - 90%
1999
Diffraction Efficiency
: 97% - 99%
G. M. Morris
OEQELabSeoul National University
Laser Pattern Generator
G. M. Morris
OEQELabSeoul National University
Micro-Optics Manufacturing Technique using Reactive Ion Etching
OEQELabSeoul National University
Microlens (I)
OEQELabSeoul National University
Microlens (II)
OEQELabSeoul National University
Microlens (III)
OEQELabSeoul National University
Wavefront Sensing
OEQELabSeoul National University
- 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
OEQELabSeoul National University
- 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
OEQELabSeoul National University
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’!
OEQELabSeoul National University
Tracor Flat-Panel ANVIS E-HUD*
OEQELabSeoul National University
Application Example
G. M. Morris
OEQELabSeoul National University
Micropattering Using DOE and Femtosecond Laser
Y. Kuroiwa et al., Optics Express, vol. 12, no. 9, pp. 1908-1915, 2004.
OEQELabSeoul National University
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
OEQELabSeoul National University
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
OEQELabSeoul National University
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.
OEQELabSeoul National University
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
Diffraction efficiency (%)
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
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)
Diffraction efficiency=84.7%
Uniformity=0.0365
(arb
. u
nit
s)(a
rb. u
nit
s)
Diffraction efficiency=84.5%
Uniformity=0.0746
(arb
. u
nit
s)(a
rb. u
nit
s)
Diffraction efficiency=84.5%
Uniformity=0.0746
(arb
. u
nit
s)(a
rb. u
nit
s)
Proposed design Conventional design
OEQELabSeoul National University
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.
OEQELabSeoul National University
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
.)
Diffraction efficiency=85.7%
Uniformity=0.113
x (sampling index) y (sampling index)
Inte
nsi
ty (
a.u
.)
x (sampling index) y (sampling index)
Inte
nsi
ty (
a.u
.)
x (sampling index) y (sampling index)
Inte
nsi
ty (
a.u
.)
Diffraction efficiency=85.7%
Uniformity=0.113
Proposed design
x (sampling index) y (sampling index)
Inte
nsi
ty (
a.u
.)
Diffraction efficiency=82.4%
Uniformity=0.401
x (sampling index) y (sampling index)
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
.)
Diffraction efficiency=82.4%
Uniformity=0.401
Conventional design
Non-monotonic optimal convergence of IFTA
OEQELabSeoul National University
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
OEQELabSeoul National University
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
OEQELabSeoul National University
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.
OEQELabSeoul National University
Ph
ase
err
or
(deg.)
X direction position index
Y direction position index
Ph
ase
err
or
(deg.)
X direction position index
Y direction position index
Ph
ase
err
or
(deg.)
X direction position index
Y direction position index
Norm
ali
zed
thic
kness
X direction position index
Y direction position index
Norm
ali
zed
thic
kness
X direction position index
Y direction position index
Norm
ali
zed
thic
kness
X direction position index
Y direction position index
No
rmali
zed
thic
kn
ess
X direction position index
Y direction position index
No
rmali
zed
thic
kn
ess
X direction position index
Y direction position index
No
rmali
zed
thic
kn
ess
X direction position index
Y direction position index
No
rmali
zed
thic
kn
ess
X direction position index
Y direction position index
No
rmali
zed
thic
kn
ess
X direction position index
Y direction position index
No
rmali
zed
thic
kn
ess
X direction position index
Y direction position index
Phase
err
or
(deg.)
X direction position index
Y d
irectio
n p
ositio
n in
dex
Phase
err
or
(deg.)
X direction position index
Y d
irectio
n p
ositio
n in
dex
Phase
err
or
(deg.)
X direction position index
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
OEQELabSeoul National University
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
OEQELabSeoul National University
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
OEQELabSeoul National University
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
OEQELabSeoul National University
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.
OEQELabSeoul National University
Theoretical studies on design and analysis of DOEs
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
OEQELabSeoul National University
Theoretical studies on design and analysis of DOEs
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
y (sampling point) x (sampling point)
,s x y
OEQELabSeoul National University
Theoretical studies on design and analysis of DOEs
Diffraction simulation
Field amplitude distribution
on the curved output surface
Field amplitude distribution
on the flat plane (z2=0)
y (sampling point) x (sampling point)
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
.)
y (sampling point) x (sampling point)
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
.)
y (sampling point) x (sampling point)
Inte
nsi
ty (
a.u
.)
y (sampling point) x (sampling point)
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
OEQELabSeoul National University
Theoretical studies on design and analysis of DOEs
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.
OEQELabSeoul National University
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
Theoretical studies on design and analysis of DOEs
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.
OEQELabSeoul National University
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
Theoretical studies on design and analysis of DOEs
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
OEQELabSeoul National University
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
OEQELabSeoul National University
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.
Experimental study on dynamic beam shaping with LC SLM
OEQELabSeoul National University
Laser
Polarizer Analyzer
CCD
LCD SLMBeam expander
1d 2df
Optical system
Laser
Polarizer Analyzer
CCD
LCD SLMBeam expander
1d 2df
LaserLaser
Polarizer Analyzer
CCD
LCD SLMBeam expander
1d 2df
Optical system
Capturingholographic
image
Recording phase
hologram
Genetic feedback tuning loop
Laser
Polarizer Analyzer
CCD
LCD SLMBeam expander
1d 2df
Optical system
Laser
Polarizer Analyzer
CCD
LCD SLMBeam expander
1d 2df
LaserLaser
Polarizer Analyzer
CCD
LCD SLMBeam expander
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.
Experimental study on dynamic beam shaping with LC SLM
OEQELabSeoul National University
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
Experimental study on dynamic beam shaping with LC SLM
OEQELabSeoul National University
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
Experimental study on dynamic beam shaping with LC SLM
The GFTL is effective in compensating the aberration of the internal optics
of the beam shaping system.
OEQELabSeoul National University
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
Experimental study on dynamic beam shaping with LC SLM
OEQELabSeoul National University
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 study on dynamic beam shaping with LC SLM
Experimental results – dynamic aberration compensation
Resulting Zernike
phase profile
OEQELabSeoul National University
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
Experimental study on dynamic beam shaping with LC SLM
OEQELabSeoul National University
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
OEQELabSeoul National University
Applications of computer generated DOEs
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
OEQELabSeoul National University
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
Experimental results
Applications of computer generated DOEs
Holographic optical tweezer
OEQELabSeoul National University
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
Applications of computer generated DOEs
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
OEQELabSeoul National University
Applications of computer generated DOEs
Simulation of full-color auto-stereoscopic video using
CG-DOEs
OEQELabSeoul National University
Stereo input video
Reconstructed stereo video (experiment)
Reconstructed stereo video (simulation)Full-color autostereoscopic 3D display demo
system
13
Applications of computer generated DOEs
Demonstration system for full-color auto-stereoscopic 3D
display using CG-DOEs
OEQELabSeoul National University
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)
Applications of computer generated DOEs
Multi-view stereoscopic display system using CG-DOEs
OEQELabSeoul National University
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
Applications of computer generated DOEs
Schematic of multi-view stereoscopic display system using
CG-DOEs
OEQELabSeoul National University
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
Applications of computer generated DOEs
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.
OEQELabSeoul National University
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
Applications of computer generated DOEs
Full-parallax 3D display system using CGHs and integral
imaging
OEQELabSeoul National University
Elemental image input
Reconstructed video
(simulation)
Reconstructed video
(experimental result)
Experimental results
Applications of computer generated DOEs
OEQELabSeoul National University
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
OEQELabSeoul National University
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
OEQELabSeoul National University
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).
OEQELabSeoul National University
Engineered DiffusersTM
- Random Microlens Screen Design Concept
Random Microlens Array Photoresist Master
* Figures are from the talk delivered by G. M. Morris in 2003.
OEQELabSeoul National University
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
OEQELabSeoul National University
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)
OEQELabSeoul National University
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)
OEQELabSeoul National University
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
OEQELabSeoul National University
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
OEQELabSeoul National University
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