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1SUSS MicroOptics SA, Switzerland; 2NAM, Ecole Polytechnique Federale de Lausann (EPFL), Switzerland
The application of laser light sources for illumination tasks like in mask aligner lithography relies on non-imaging optical systems with multi-aperture elements for beam shaping. When simulating such systems, the traditional approach is to separate the beam-shaping part (incoherent simulation) from dealing with coherence properties of the illuminating laser light source (diffraction theory with statistical treatment). We present an approach using Gaussian beam decomposition to include coherence simulation into ray tracing, combining these two parts, to get a complete picture in one simulation. We discuss source definition for such simulations, and verify our assumptions on a well-known system. We then apply our approach to an imaging beam shaping setup with microoptical multi-aperture elements. We compare the simulation to measurements of a similar beam-shaping setup with a 193 nm continuous-wave laser in a mask-aligner configuration.
8:45 - 9:00 ID: 175 / S01: 2 Manufacturing, Tolerancing, and Testing of Optical Systems (MOS)
Development of a Cost-Efficient Computer Controlled Optical Surfacing Process for Correcting Aspheric Lenses using Tool Influence Function based Dwelltime Optimization
Pei Liang Low, Wilhelmus A. C. M. Messelink, Rene Weber
Edmund Optics Singapore Pte. Lte.
A Computer Controlled Optical Surfacing (CCOS) system has been developed for correcting form errors on aspheric surfaces. Experiments were carried out to find the correlation between different polishing parameters and polishing metrics such as removal rate, uniformity etc. Based on established polishing parameters, polishing process is developed to correct surface errors on planar, spherical and aspheric surfaces. A convolution model between TIF and dwell times was developed to simulate and solve for correction polishing. Surface accuracies of peak-to-valley (PV) 141 nm and root-mean-squared (RMS) 22 nm has been achieved for planar surface. For aspheric surface, current accuracy of 662 nm PV and of 115 nm RMS is achieved with further development ongoing.
9:00 - 9:15 ID: 126 / S01: 3 Manufacturing, Tolerancing, and Testing of Optical Systems (MOS)
Increasing the Laser-Induced Damage Threshold of Optical Components by Atmospheric Pressure Plasma Surface Finishing
Christoph Gerhard, Marco Stappenbeck, Daniel Tasche
University of Applied Sciences and Arts, Germany
In this contribution, a plasma-based approach for finishing optics surfaces is introduced. Experiments were performed on classically manufactured zinc crown glass and sapphire. It is shown that the use of direct dielectric barrier discharge plasma at atmospheric pressure allows the removal of surface-adherent carbonaceous contaminations that were induced by classical manufacturing. Moreover, the use of such plasma leads to a certain decrease in surface roughness. Both effects, surface cleaning and smoothing finally increase the laser-induced damage threshold of optical components.
9:15 - 9:30 ID: 167 / S01: 4 Manufacturing, Tolerancing, and Testing of Optical Systems (MOS)
Thermal Development Inside The Workpiece During A Polishing Process
Michael Frederik Benisch, Werner Bogner, Rolf Rascher
Technische Hochschule Deggendorf, Germany
The generation of heat during a manufacturing process corresponds to the energy generated by the process and introduced into work piece, tool and polishing suspension. Therefore, it is monitored while processing. Components are equipped with a temperature sensor and polished. These “smart work pieces” help understanding the thermal effects during polishing. When polishing, a speed and pressure dependent change of the temperature is measured. A method for the integration of temperature sensors and for the measurement during a polishing process is shown. The effect of different speeds and pressures on the temperature process is investigated.
9:30 - 9:45 ID: 143 / S01: 5 Manufacturing, Tolerancing, and Testing of Optical Systems (MOS)
Topology Optimization And Additive Manufacturing Of An Optical Housing For Space Applications
Nils Heidler1, Henrik von Lukowicz1,2, Enrico Hilpert1,2, Stefan Risse1, Lucas Alber3, Jan Klement3, Frank Heine3, Ralf Bölter3, Josep Maria Perdigues Armengol4
1Fraunhofer Institute for Applied Optics and Precision Engineering IOF, Jena, Germany; 2Institute of Applied Physics, Friedrich-Schiller-University, Jena, Germany; 3Tesat-Spacecom GmbH & Co. KG, Backnang, Germany; 4ESA/ESTEC, Noordwijk, Netherlands
The design of an optical housing for laser telecommunication in space is improved by topology optimization. Different mechanical and thermal boundary conditions are considered while minimizing the overall weight of the housing. As a proof-of-concept study, a complex and lightweight housing is made by additive manufacturing with the aluminium silicon alloy AlSi40. Post processing steps include a thermal treatment, cleaning and a mechanical machining process. Final characterization tests include the evaluation of material characteristics by tensile tests, a computed tomography scan and a CMM measurement. The final shock and vibrational test is used to proof the performance of the housing for future space applications.