发明授权
- 专利标题： Optical instrument, and device manufacturing method
- 专利标题（中）： 光学仪器和器件制造方法
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申请号： US09678255申请日： 2000-10-03
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公开(公告)号： US06740893B1公开(公告)日： 2004-05-25
- 发明人: Masayuki Tanabe
- 申请人： Masayuki Tanabe
- 优先权： JP11-283569 19991004
- 主分类号： G21G500
- IPC分类号： G21G500
摘要：
An optical instrument includes an optical element and a detector for detecting an impurity concentration in an ambience containing a space surrounding the optical element. By controlling the impurity concentration on the basis of an output of the detector, deposition of impurities on the optical element and deterioration of the optical characteristic of the optical element thereby can be prevented effectively.