2013 Fiscal Year Final Research Report

Development of Birefringence Analysis Code for Single Crystal Optical Elements

Research Project

Project/Area Number	24656086
Research Category	Grant-in-Aid for Challenging Exploratory Research
Allocation Type	Single-year Grants
Research Field	Materials/Mechanics of materials
Research Institution	Kyoto University
Principal Investigator	MIYAZAKI Noriyuki 京都大学, 工学(系)研究科(研究院), 名誉教授 (10166150)
Project Period (FY)	2012-04-01 – 2014-03-31
Keywords	複屈折 / 残留応力 / クリープ変形 / 有限要素法
Research Abstract	Steady state creep constitutive equation was formulated using the experimental data on compressive tests under constant strain rates at elevated temperatures. Residual stress in a calcium fluoride single crystal ingot after ingot annealing was calculated by the nonlinear finite element analysis using the steady state creep constitutive equation. In the birefringence analysis, optical path difference was obtained from the residual stress. The distributions of the optical path difference obtained from the analysis were compared with those of experimental measurements. It is found that analysis results agree well with experimental measurements. Thus the subsystem for residual stress estimation was verified. The birefringence was estimated for a calcium fluoride single crystal chamber window of an ArF excimer laser light source with a wave a length of 193nm used in a semiconductor lithography system.