Open Access

ARTICLE

Birefringence Simulations of Calcium Fluoride Single Crystal Used as Chamber Window of Gas Laser Light Source

Yuta Kitamura¹, Noriyuki Miyazaki¹, Takahito Kumazaki², Naoto Nagakura³, Yasuhiro Hashimoto³, Isao Masada³

1 Department of Mechanical Engineering and Science, Kyoto University, Kyoto, 606-8501, Japan
2 Development Division, Gigaphoton INC., Tochigi, 323-8558, Japan
3 CF-10 Department, Research and Development Division, Tokuyama Corporation, Yamaguchi, 745-8648, Japan

Computer Modeling in Engineering & Sciences 2010, 68(2), 151-166. https://doi.org/10.3970/cmes.2010.068.151

Abstract

CaF₂ single crystal is used as high performance optical elements. We developed an analysis system for simulating birefringence of CaF₂ single crystal used as a chamber window of a gas laser light source. The analysis system consists of a stress analysis and a birefringence analysis. In the stress analysis, the finite element method was applied to obtain the mechanical stress caused by a window holder and gas pressure. In the birefringence analysis, the photo-elastic effect gives the change of refractive indices, from which the optical path difference and the fast axis are calculated by using the average stress method. The crystal anisotropy of CaF₂ single crystal was taken into account in these analyses. We can perform a birefringence simulation for a chamber window of CaF₂ single crystal with any crystal direction and any incident direction, using this analysis system. We performed the analyses of a crystal with a surface vertical to the <111> direction under the Brewster's angle of incidence and several rotation angles. From these analyses, we obtained reasonable results of the optical path difference and the fast axis in comparison with experimental results.

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