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 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)
Neuchâtel, Swiss Watch Valley
SMO is “Preferred Supplier” for Carl Zeiss SMT AG: DUV Laser Beam Shaping Solutions (ASML Steppers)
2 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
Mean -0.10 Unwrapped phase / lambda
RMS 0.34 1260.77 P-V 2.94
0.72 1008.62 Refractive Microlens Arrays (ROE) Binary Optics Diffractive Optical Elements (DOE)
0.13 756.46
-0.46 y / norm. radius
-1.04
Phase / lambda 504.31
-1.63
252.15 Random Diffusers Microlens Imprint Wafer-Level MO Exposure Optics (Mask Aligner) -2.22
Lithography Camera (WLC) 0.00 0.00 252.15 504.31 756.46 1008.62 1260.77 R. Völkel, “Illumination of DLP® with Laser Light Sources”, 4th International Symposium on Emerging and Industrial DLP® Applications”, Frankfurt, Germany, Nov 12, 2009 3 x / norm. radius 10.02.2005 Zeiss Diffusor 6101 HH, 10-02-05 RV 14:49:32 SUSS MicroOptics Micro-Optics Solutions
Semiconductor Technology Industrial Optics & Vision Healthcare & Life Science Metrology Laser & Material Processing Information Technology Mean -0.10 Unwrapped phase / lambda
RMS 0.34 1260.77 Research P-V 2.94
0.72 1008.62
0.13 756.46
-0.46 y / norm. radius
-1.04
Phase / lambda 504.31
-1.63 252.15
-2.22 0.00 0.00 252.15 504.31 756.46 1008.62 1260.77 x / norm. radius 10.02.2005 Zeiss Diffusor 6101 HH, 10-02-05 RV SUSS MicroOptics R. Völkel, “Illumination of DLP® with Laser Light Sources”, 4th International Symposium14:49:32 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
6 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!
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)
7 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
8 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 R. Völkel, “Illumination of DLP® with Laser Light Sources”, 4th International Symposium on Emerging and Industrial DLP® Applications”, Frankfurt, Germany, Nov 12, 2009 The Köhler Illumination Concept
A success-story since 1893
Our MicroOptics set the Standards 1893: August Köhler invented Köhler Illumination
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 muenchen.de/koehler.html and the numerical aperture of the object - illumination in a microscope independent
from each other. Image: http://www.mikroskopieImage:
August Köhler, Zeitschrift für wissenschaftliche Mikroskopie, Band X, Seite 433-440 (1893)
11 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
Field Aperture Diaphragm Diaphragm Object Light Plane Source C B
A Collector Condensor Lens Lens
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.
12 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
Egyptian God Ra with Madame Taperet , 1000 BC (Louvre, Paris)
Thomsas A. Edison (Patent 1880)
13 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
14 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.
http://www.rp-photonics.com/lasers.html
15 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
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)
16 R. Völkel, “Illumination of DLP® with Laser Light Sources”, 4th International Symposium on Emerging and Industrial DLP® Applications”, Frankfurt, Germany, Nov 12, 2009 Tasks for Micro-Optics
Intensity
LED Plastic, Glass
LED Homogenization Reflector Substrate
Beam Collimation Beam Shaping
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.
18 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 1 N
19 R. Völkel, “Illumination of DLP® with Laser Light Sources”, 4th International Symposium on Emerging and Industrial DLP® Applications”, Frankfurt, Germany, Nov 12, 2009 The Köhler Integrator* – Multiple Köhler Illumination Systems in Parallel
*Also known as Fly‟s Eye Condenser, Optical Integrator, Microlens Beam Homogenizer, Wabenkondensor, …
Our MicroOptics set the Standards Köhler Integrator – Fly’s Eye Condenser
Principle Ray Condenser Lens
Object
Plane Image Plane Image
Light Source Example: Gaussian intensity distribution at lens array LA1 Field Lens
Lens Array MLA1 Lens Array MLA2 (Conjugated to object) (Images of light source) Projection Lens (Multiple images of source)
Multiple Köhler illumination in parallel to further improve illumination.
Splitting of the field diaphragm. Source: Naumann, Schröder, Bauelemente der Optik, Hanser Verlag Hanser Optik, der Bauelemente Schröder, Naumann, Source:
21 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
22 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
I(x) I(x)
x x Microlens Array Beam Homogenizier
Raw Beam Flat Top (Square) Flat Top (Line)
23 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
24 R. Völkel, “Illumination of DLP® with Laser Light Sources”, 4th International Symposium on Emerging and Industrial DLP® Applications”, Frankfurt, Germany, Nov 12, 2009 Most Popular Illumination Systems for DLP®
Our MicroOptics set the Standards 25 Standard Mirror Postitions
26 R. Völkel, “Illumination of DLP® with Laser Light Sources”, 4th International Symposium on Emerging and Industrial DLP® Applications”, Frankfurt, Germany, Nov 12, 2009 27 R. Völkel, “Illumination of DLP® with Laser Light Sources”, 4th International Symposium on Emerging and Industrial DLP® Applications”, Frankfurt, Germany, Nov 12, 2009 28 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®
29 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
30 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
POWELL LENS
31 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
Our MicroOptics set the Standards Köhler Integrator – Beam Homogenizer
imaging
Flat-Top Size Flat-Top Divergence f FL 1 dIN 2 pLA DFT fLA2 pLA DFT PLA1 fLA1 fLA2 a12 tan fLA1 fLA2 2 fFL fLA1 fFL
where fLA1 a12 fLA1 fLA2
a12 : separationof LA1 and LA2
Literature: Fred M. Dickey and Scott C. Holswade Laser Beam Shaping: Theory and Techniques Publisher: Marcel Dekker, (2000).
33 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
Example: Gaussian intensity distribution at
lens array LA1
Simulation of superposition in object plane for two identical microlens arrays consisting of NxN identical lenses.
34 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.
35 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. f The period Λ is given by: FL FP FP pLA The number of spots N is equivalent to the Fresnel p2 LA number FN of the microlens array. N 4 FNLA fLA
*Norbert Streibl, Review Paper “Beam shaping with optical array generators” Journal of Modern Optics, Vol.36, No.12, 1559-1573 (1989)
36 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
Dermatology Hair Removal Tattoo Removal Pigment Treatment Skin Rejuvenation
Source: www.palomarmedical.com
37 R. Völkel, “Illumination of DLP® with Laser Light Sources”, 4th International Symposium on Emerging and Industrial DLP® Applications”, Frankfurt, Germany, Nov 12, 2009 Interference and Talbot Effect
Our MicroOptics set the Standards 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) Fractional Talbot plane
40 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 R. Völkel, “Illumination of DLP® with Laser Light Sources”, 4th International Symposium on Emerging and Industrial DLP® Applications”, Frankfurt, Germany, Nov 12, 2009 Random Diffusers
Our MicroOptics set the Standards Rotating Ground-Glass Diffuser
Rotating diffuser - Time averaging - Extended light source
43 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
No diffuser Rotating diffuser
Uniformity: > 10 % Uniformity: << 5 %
Experiment: Laser Diode, 670 nm, condenser lens ƒFL = 40 mm
44 R. Völkel, “Illumination of DLP® with Laser Light Sources”, 4th International Symposium on Emerging and Industrial DLP® Applications”, Frankfurt, Germany, Nov 12, 2009 Shaping of Random Diffusers
Ground Glass Diffuser 1 300 m 1 160 m 1 500 m
2 100 m 2 70 m 2 160 m
Shaped Random Diffuser (2D)
45 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.
46 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
Online Shop: www.suss.ch/shop
47 R. Völkel, “Illumination of DLP® with Laser Light Sources”, 4th International Symposium on Emerging and Industrial DLP® Applications”, Frankfurt, Germany, Nov 12, 2009