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Proceedings Paper

Minimizing interference in microlens array homogenizer for a coherent UV laser
Author(s): Sten A. Lindau
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Paper Abstract

A Gaussian to top-hat beam homogenizer has been designed and fabricated for a UV laser illumination system used in the manufacture of integrated circuit substrates. An important part of the system is a “coherence buster” which is used for minimizing interference effects, normally encountered when using microlens array homogenizers together with a coherent light source. The coherence buster is a diffraction grating, which introduces a time delay across the beam. If this time delay is sufficiently large in comparison to the pulse length, it can be so arranged that beams, which would normally interfere, now arrives at different times and therefore add incoherently. The theory behind the coherence reduction is described, as well as the design of the grating. The irradiance uniformity of the manufactured homogenizer has been measured, and shown to be free from interference fringes.

Paper Details

Date Published: 15 October 2012
PDF: 8 pages
Proc. SPIE 8490, Laser Beam Shaping XIII, 84900G (15 October 2012); doi: 10.1117/12.929686
Show Author Affiliations
Sten A. Lindau, Micronic Mydata AB (Sweden)

Published in SPIE Proceedings Vol. 8490:
Laser Beam Shaping XIII
Andrew Forbes; Todd E. Lizotte, Editor(s)

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