Coherence management for microlens laser beam homogenizers

Lars Erdmann; Matthias Burkhardt; Robert Brunner

doi:10.1117/12.479646

16 August 2002 Coherence management for microlens laser beam homogenizers

Lars Erdmann, Matthias Burkhardt, Robert Brunner

Proceedings Volume 4775, Modeling and Characterization of Light Sources; (2002) https://doi.org/10.1117/12.479646
Event: International Symposium on Optical Science and Technology, 2002, Seattle, WA, United States

Abstract

We suggest an optical system for beam homogenization and speckle reduction of spatially highly coherent Laser beams. The new method is applicable to laser beams with moderate temporal coherence. Based on the finite temporal coherence the spatial coherence is reduced prior to the homogenizer component. The new design was experimentally tested for ArF - Excimer laser at 193nm. For this Deep UV application we used silicon micromirrors in combination with fused silica microlenses with a pitch of 150 μm . In contrast to former fly's eye homogenizers for laser beams the new method employs a large number of sub-apertures even for lasers with high spatial coherence. This results in a speckle free and uniform intensity distribution in the target plane. Furthermore the pupil filling can be increased drastically. Experimental results for a DUV microscopy application are presented and discussed.

Citation Download Citation

Lars Erdmann, Matthias Burkhardt, and Robert Brunner "Coherence management for microlens laser beam homogenizers", Proc. SPIE 4775, Modeling and Characterization of Light Sources, (16 August 2002); https://doi.org/10.1117/12.479646

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