Irradiance models for projection optics

R.W.H. Merks, Michel Habets, Siep Weiland, Wim Coene

Research output: Contribution to conferenceOtherAcademic


Thermally induced deformations of optical elements influence the performance of high precision optical projection systems. For extreme ultraviolet (EUV) lithography, the mirrors each absorb approximately 35% of the incident power. The thermally induced deformations are for this reason mainly a result of the irradiance on the mirrors. Measuring the temperature distribution and/or the deformations of the mirrors is impractical. In order to determine and predict the induced deformations for design as well as control purposes irradiance models can be utilized.

Propagation of light can be simulated using ray tracing. A full ray tracing approach could be used to determine the irradiance on the elements accurately, but this approach requires hours of calculation time. In this presentation faster
approaches are proposed and compared to full ray tracing.
Original languageEnglish
Number of pages1
Publication statusPublished - 2015
Event34th Benelux Meeting on Systems and Control, March 24-26, 2015, Lommel, Belgium - Center Parcs "De Vossemeren", Lommel, Belgium
Duration: 24 Mar 201526 Mar 2015


Conference34th Benelux Meeting on Systems and Control, March 24-26, 2015, Lommel, Belgium
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