Our MicroOptics set the Standards Illumination of DLP ® with Laser Light Sources Dr. Reinhard Voelkel SUSS MicroOptics SA, Neuchâtel, Switzerland www.suss.ch, [email protected]
Our MicroOptics set the Standards
Illumination of DLP® with Laser
Light Sources
Dr. Reinhard VoelkelSUSS MicroOptics SA, Neuchâtel, Switzerland
www.suss.ch, [email protected]
R. Völkel, “Illumination of DLP® with Laser Light Sources”, 4th International Symposium on Emerging and Industrial DLP® Applications”, Frankfurt, Germany, Nov 12, 2009
SUSS MicroOptics – We Set The Standards
World leading supplier of Micro-Optics
8‟‟ Wafer Technology, Wafer-Level Packaging, SUSS Imprint Lithography
More than 200 active customers, e.g. to SEMI equipment manufacturers, Laser
& Optics industry, Sensors & Metrology and Medical
Part of the SUSS MicroTec Group (www.suss.com)
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Neuchâtel, Swiss Watch Valley
SMO is “Preferred Supplier” for Carl Zeiss SMT AG:
DUV Laser Beam Shaping Solutions (ASML Steppers)
R. Völkel, “Illumination of DLP® with Laser Light Sources”, 4th International Symposium on Emerging and Industrial DLP® Applications”, Frankfurt, Germany, Nov 12, 2009
SUSS MicroOptics
Unwrapped phase / lambda
Zeiss Diffusor 6101 HH, 10-02-05 RV
SUSS MicroOptics
x / norm. radius
0.00 1260.77252.15 504.31 756.46 1008.62
y /
no
rm.
rad
ius
12
60
.77
0.0
01
00
8.6
27
56
.46
50
4.3
12
52
.15
Ph
ase
/ l
am
bd
a
-2.22
-1.63
-1.04
-0.46
0.13
0.72
10.02.2005
14:49:32
Mean -0.10
RMS 0.34
P-V 2.94
Refractive Microlens Arrays (ROE) Binary Optics Diffractive Optical Elements (DOE)
Random Diffusers Microlens Imprint
Lithography
3
MO Exposure Optics (Mask Aligner)Wafer-Level
Camera (WLC)
R. Völkel, “Illumination of DLP® with Laser Light Sources”, 4th International Symposium on Emerging and Industrial DLP® Applications”, Frankfurt, Germany, Nov 12, 2009
Micro-Optics Solutions
Semiconductor Technology
Industrial Optics & Vision
Healthcare & Life Science
Metrology
Laser & Material Processing
Information Technology
Research
Unwrapped phase / lambda
Zeiss Diffusor 6101 HH, 10-02-05 RV
SUSS MicroOptics
x / norm. radius
0.00 1260.77252.15 504.31 756.46 1008.62
y /
no
rm.
rad
ius
12
60
.77
0.0
01
00
8.6
27
56
.46
50
4.3
12
52
.15
Ph
ase
/ l
am
bd
a
-2.22
-1.63
-1.04
-0.46
0.13
0.72
10.02.2005
14:49:32
Mean -0.10
RMS 0.34
P-V 2.94
R. Völkel, “Illumination of DLP® with Laser Light Sources”, 4th International Symposium on Emerging and Industrial DLP® Applications”, Frankfurt, Germany, Nov 12, 2009
DLP®? What are we talking about?
The Holy Grail of MEMS Technology!
Larry J. Hornbeck:
„The Weirdest Technoloy Ever Invented“
A very sucessful device that
our customers want to illuminate!
5
R. Völkel, “Illumination of DLP® with Laser Light Sources”, 4th International Symposium on Emerging and Industrial DLP® Applications”, Frankfurt, Germany, Nov 12, 2009
DLP® Standard Mirror Postitions
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R. Völkel, “Illumination of DLP® with Laser Light Sources”, 4th International Symposium on Emerging and Industrial DLP® Applications”, Frankfurt, Germany, Nov 12, 2009
Illumination: Optics Is Light Work!
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Light Sources Devices, Systems
„Collect all photons and illuminate the DLP®!“
Performance (brightness, contrast, color,
uniformity, efficiency)
Size (large, smaller device)
Costs (manufacturing, energy saving, lifetime)
R. Völkel, “Illumination of DLP® with Laser Light Sources”, 4th International Symposium on Emerging and Industrial DLP® Applications”, Frankfurt, Germany, Nov 12, 2009
Illumination Today: More Power – Less Energy!
Uniformity
Efficiency
Costs
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R. Völkel, “Illumination of DLP® with Laser Light Sources”, 4th International Symposium on Emerging and Industrial DLP® Applications”, Frankfurt, Germany, Nov 12, 2009
Optics: Our Gurus
Thousands of books and patents on optical lens design
How many books are describing illumination systems?
Illumination is always the “little brother” of the glorious lens design –
nobody wants to play with – except if we really have to!
9
Our MicroOptics set the Standards
The Köhler Illumination Concept
A success-story since 1893
R. Völkel, “Illumination of DLP® with Laser Light Sources”, 4th International Symposium on Emerging and Industrial DLP® Applications”, Frankfurt, Germany, Nov 12, 2009
1893: August Köhler invented Köhler Illumination
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Image: htt
p:/
/ww
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ikro
skopie
-muenchen.d
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oehle
r.htm
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In 1893 August Köhler (1866–1948) from Carl Zeiss in
Jena, introduced a new and revolutionary method for
uniform illumination of specimen in an optical
microscope in his doctoral thesis.
The Köhler method allows to adjust the size
and the numerical aperture of the object
illumination in a microscope independent
from each other.
August Köhler, Zeitschrift für wissenschaftliche
Mikroskopie, Band X, Seite 433-440 (1893)
R. Völkel, “Illumination of DLP® with Laser Light Sources”, 4th International Symposium on Emerging and Industrial DLP® Applications”, Frankfurt, Germany, Nov 12, 2009
The Basic Principle of Köhler Illumination
A. The collector lens images the light source to the plane of the aperture diaphragm
B. The aperture diaphragm is located in the front focal plane of the condenser lens
C. The field diaphragm is imaged to the object plane by properly adjusting the distance
of the condenser lens to the object plane.
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Field
Diaphragm
Aperture
Diaphragm
Collector
LensCondensor
Lens
Light
Source
Object
Plane
A
BC
R. Völkel, “Illumination of DLP® with Laser Light Sources”, 4th International Symposium on Emerging and Industrial DLP® Applications”, Frankfurt, Germany, Nov 12, 2009
Light Sources
13
Egyptian God Ra with Madame Taperet , 1000 BC (Louvre, Paris)
Thomsas A. Edison (Patent 1880)
R. Völkel, “Illumination of DLP® with Laser Light Sources”, 4th International Symposium on Emerging and Industrial DLP® Applications”, Frankfurt, Germany, Nov 12, 2009
Lighting Roadmap
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R. Völkel, “Illumination of DLP® with Laser Light Sources”, 4th International Symposium on Emerging and Industrial DLP® Applications”, Frankfurt, Germany, Nov 12, 2009
Types of LASERs
Semiconductor lasers (laser diodes), quantum cascade lasers, surface-
emitting semiconductor lasers (VCSELs, VECSELs)
Solid-state lasers based on ion-doped crystals or glasses, pumped
with discharge lamps or laser diodes (Nd:YAG, Nd:YVO4, Nd:YLF,
Nd:glass, Yb:YAG, Yb:glass, Ti:sapphire, Cr:YAG and Cr:LiSAF).
Fiber lasers, based on optical glass fibers which are doped with some
laser-active ions in the fiber core.
Gas lasers (e.g. helium–neon lasers, CO2 lasers, and argon ion lasers)
and excimer lasers (ArF, KrF, XeF, and F2).
Chemical and nuclear pumped lasers, free electron lasers, and X-ray
lasers.
15
http://www.rp-photonics.com/lasers.html
R. Völkel, “Illumination of DLP® with Laser Light Sources”, 4th International Symposium on Emerging and Industrial DLP® Applications”, Frankfurt, Germany, Nov 12, 2009
Richard Ulbricht Invented The Ulbricht Sphere
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Dr. Richard Ulbricht (1849 – 1923, Dresden)
Invented the Ulbricht Sphere when he was trying to find the optimium
optics for electrical illumination of Dresden„s train stations (≈ 1891)
R. Völkel, “Illumination of DLP® with Laser Light Sources”, 4th International Symposium on Emerging and Industrial DLP® Applications”, Frankfurt, Germany, Nov 12, 2009
LED
Reflector
LED
Substrate
Beam Collimation Beam Shaping
Intensity
Homogenization
Plastic, Glass
Tasks for Micro-Optics
R. Völkel, “Illumination of DLP® with Laser Light Sources”, 4th International Symposium on Emerging and Industrial DLP® Applications”, Frankfurt, Germany, Nov 12, 2009
Conservation of Etendue – Lagrange Invariant
Etendue is a property of an optical system, which characterizes how
"spread out" the light is in area and angle.
Lagrange invariant is a measure of the light propagating through an
optical system. For a given optical system, the Lagrange invariant is a
constant throughout all space, that is, it is invariant upon refraction and
transfer.
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R. Völkel, “Illumination of DLP® with Laser Light Sources”, 4th International Symposium on Emerging and Industrial DLP® Applications”, Frankfurt, Germany, Nov 12, 2009
Speckles
When traveling through an optical system,
the different laser modes acquire different phase shifts
and a speckle pattern is observed in the flat-top.
The contrast of this speckle pattern depends on the
coherence length of the transmitted beam. It will vanish if
the optical path length difference between the fastest and slowest
modes exceeds the longitudinal coherence length of the laser beam.
Temporary integration: A dynamic change in the speckle pattern from
shot to shot results in an averaging out of the residual granularity
contrast according to
19
N
1
Our MicroOptics set the Standards
The Köhler Integrator* – Multiple Köhler
Illumination Systems in Parallel
*Also known as Fly‟s Eye Condenser, Optical Integrator,
Microlens Beam Homogenizer, Wabenkondensor, …
R. Völkel, “Illumination of DLP® with Laser Light Sources”, 4th International Symposium on Emerging and Industrial DLP® Applications”, Frankfurt, Germany, Nov 12, 2009
Köhler Integrator – Fly’s Eye Condenser
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Example: Gaussian intensity distribution at lens array LA1
Light
Source
Principle Ray
Field Lens
Projection Lens(Multiple images of source)
Object
Plane
Lens Array MLA1
(Conjugated to object)
Lens Array MLA2
(Images of light source)
Condenser Lens
Ima
ge
Pla
ne
Sourc
e: N
aum
ann, S
chrö
der,
Bauele
mente
der
Optik, H
anser
Verlag
Multiple Köhler illumination in parallel to further improve illumination.
Splitting of the field diaphragm.
R. Völkel, “Illumination of DLP® with Laser Light Sources”, 4th International Symposium on Emerging and Industrial DLP® Applications”, Frankfurt, Germany, Nov 12, 2009
Köhler Integrator – Fly‘s Eye Illumination
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R. Völkel, “Illumination of DLP® with Laser Light Sources”, 4th International Symposium on Emerging and Industrial DLP® Applications”, Frankfurt, Germany, Nov 12, 2009
Köhler Integrator for Laser Beam Homogenizing
Redistributing the irradiance of arbitrarily input beams to a flat-top
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I(x)
x
I(x)
x
Raw Beam Flat Top (Square) Flat Top (Line)
Microlens Array
Beam Homogenizier
R. Völkel, “Illumination of DLP® with Laser Light Sources”, 4th International Symposium on Emerging and Industrial DLP® Applications”, Frankfurt, Germany, Nov 12, 2009
Recent Patents by Zeiss, ASML, Nikon & Canon
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Our MicroOptics set the Standards
Most Popular Illumination Systems for DLP®
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R. Völkel, “Illumination of DLP® with Laser Light Sources”, 4th International Symposium on Emerging and Industrial DLP® Applications”, Frankfurt, Germany, Nov 12, 2009
Standard Mirror Postitions
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R. Völkel, “Illumination of DLP® with Laser Light Sources”, 4th International Symposium on Emerging and Industrial DLP® Applications”, Frankfurt, Germany, Nov 12, 200927
R. Völkel, “Illumination of DLP® with Laser Light Sources”, 4th International Symposium on Emerging and Industrial DLP® Applications”, Frankfurt, Germany, Nov 12, 200928
R. Völkel, “Illumination of DLP® with Laser Light Sources”, 4th International Symposium on Emerging and Industrial DLP® Applications”, Frankfurt, Germany, Nov 12, 2009
Illumination Systems for DLP®
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R. Völkel, “Illumination of DLP® with Laser Light Sources”, 4th International Symposium on Emerging and Industrial DLP® Applications”, Frankfurt, Germany, Nov 12, 2009
Light Mixing in Rod or Tunnel
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R. Völkel, “Illumination of DLP® with Laser Light Sources”, 4th International Symposium on Emerging and Industrial DLP® Applications”, Frankfurt, Germany, Nov 12, 2009
Refractive Homogenizer for Gaussian Laser Beams
http://www.mt-berlin.com/frames_home/homefr_set_shapers.htm
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POWELL LENS
Our MicroOptics set the Standards
Köhler Integrator for Laser Beam
Homogenizing
R. Völkel, “Illumination of DLP® with Laser Light Sources”, 4th International Symposium on Emerging and Industrial DLP® Applications”, Frankfurt, Germany, Nov 12, 2009
Köhler Integrator – Beam Homogenizer
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2112
21121
1221
21
1
: LAandLAofseparationa
ffafwhere
affff
fPD
LALALA
LALA
LALA
LAFTFL
FLLA
LALA
FL
FTLAIN
ff
pf
f
Dpd
1
22
2
1tan
Flat-Top Size Flat-Top Divergence
imaging
Literature: Fred M. Dickey and Scott C. Holswade
Laser Beam Shaping: Theory and Techniques
Publisher: Marcel Dekker, (2000).
R. Völkel, “Illumination of DLP® with Laser Light Sources”, 4th International Symposium on Emerging and Industrial DLP® Applications”, Frankfurt, Germany, Nov 12, 2009
Köhler Integrator illuminated with a Gaussian Beam
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Example:
Gaussian intensity distribution at lens array LA1
Simulation of superposition in object plane for two identical microlens arrays consisting of NxN identical lenses.
R. Völkel, “Illumination of DLP® with Laser Light Sources”, 4th International Symposium on Emerging and Industrial DLP® Applications”, Frankfurt, Germany, Nov 12, 2009
Where is the Problem?
The concepts of Köhler illumination and Köhler integrators are well
understood and successfully implemented in many optical systems.
High-quality microlens arrays in Fused Silica are well suited for high-
power laser applications and available on large scale.
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R. Völkel, “Illumination of DLP® with Laser Light Sources”, 4th International Symposium on Emerging and Industrial DLP® Applications”, Frankfurt, Germany, Nov 12, 2009
Köhler Integrator as Array Generator
For illumination with a coherent and collimated
laser beam, the flat-top in the object plane is
modulated – or even subdivided into sharp peaks.
Each focal spot corresponds to the Fourier
transformation of the light source [Streibl*].
The microlens pitch pLA and the focal length of the
condenser lens ƒFL define the period ΛFP in the
object plane.
The period ΛFP is given by:
The number of spots N is equivalent to the Fresnel
number FN of the microlens array.
36
LA
FLFP
p
f
LA
LA
FNf
pN LA 4
2
*Norbert Streibl, Review Paper “Beam shaping with optical array generators”
Journal of Modern Optics, Vol.36, No.12, 1559-1573 (1989)
R. Völkel, “Illumination of DLP® with Laser Light Sources”, 4th International Symposium on Emerging and Industrial DLP® Applications”, Frankfurt, Germany, Nov 12, 2009
Microlens Array Generator for Medical Applications
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Dermatology
Hair Removal
Tattoo Removal
Pigment Treatment
Skin Rejuvenation
Source: www.palomarmedical.com
Our MicroOptics set the Standards
Interference and Talbot Effect
R. Völkel, “Illumination of DLP® with Laser Light Sources”, 4th International Symposium on Emerging and Industrial DLP® Applications”, Frankfurt, Germany, Nov 12, 2009
Illumination of DLP® using Laser and Köhler Integrator
39
R. Völkel, “Illumination of DLP® with Laser Light Sources”, 4th International Symposium on Emerging and Industrial DLP® Applications”, Frankfurt, Germany, Nov 12, 2009
Talbot Effect for Periodic Microlens Arrays
Diffraction simulation (Gaussian Beamlets)
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Fractional Talbot plane
R. Völkel, “Illumination of DLP® with Laser Light Sources”, 4th International Symposium on Emerging and Industrial DLP® Applications”, Frankfurt, Germany, Nov 12, 2009
Modulation in the Flat-Top
41
?
Our MicroOptics set the Standards
Random Diffusers
R. Völkel, “Illumination of DLP® with Laser Light Sources”, 4th International Symposium on Emerging and Industrial DLP® Applications”, Frankfurt, Germany, Nov 12, 2009
Rotating Ground-Glass Diffuser
43
Rotating diffuser
- Time averaging
- Extended light source
R. Völkel, “Illumination of DLP® with Laser Light Sources”, 4th International Symposium on Emerging and Industrial DLP® Applications”, Frankfurt, Germany, Nov 12, 2009
Rotating Diffuser for Köhler Integrator
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No diffuser Rotating diffuser
Experiment: Laser Diode, 670 nm, condenser lens ƒFL = 40 mm
Uniformity: > 10 % Uniformity: << 5 %
R. Völkel, “Illumination of DLP® with Laser Light Sources”, 4th International Symposium on Emerging and Industrial DLP® Applications”, Frankfurt, Germany, Nov 12, 2009
m
m
70
160
2
1
m
m
160
500
2
1
m
m
100
300
2
1
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Shaping of Random Diffusers
Ground Glass Diffuser
Shaped Random Diffuser (2D)
R. Völkel, “Illumination of DLP® with Laser Light Sources”, 4th International Symposium on Emerging and Industrial DLP® Applications”, Frankfurt, Germany, Nov 12, 2009
Conclusion
Is there a chance for perfect illumination of DLP® using lasers?
YES, but not for all lasers and all applications.
Speckles, interference effects, Talbot, ... will always be a problem
The best solution seems to be a combination of different optical and micro-
optical elements.
A Köhler Integrator, the flat-top is placed into the entrance pupil of
A light mixing rod or – better tunnel, plus
A random diffusing element to introduce angular spreading of the
coherent source beam greater than the angular separation of the
interference effects due to the imaging homogenizer array
Temporary integration, time averaging of speckles by rotating diffuser,
membranes or other devices.
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R. Völkel, “Illumination of DLP® with Laser Light Sources”, 4th International Symposium on Emerging and Industrial DLP® Applications”, Frankfurt, Germany, Nov 12, 2009
SUSS.
Our Solutions
Set Standards
SUSS MicroTec: www.suss.com
SUSS MicroOptics www.suss.ch
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Online Shop: www.suss.ch/shop