The patent badge is an abbreviated version of the USPTO patent document. The patent badge does contain a link to the full patent document.
The patent badge is an abbreviated version of the USPTO patent document. The patent badge covers the following: Patent number, Date patent was issued, Date patent was filed, Title of the patent, Applicant, Inventor, Assignee, Attorney firm, Primary examiner, Assistant examiner, CPCs, and Abstract. The patent badge does contain a link to the full patent document (in Adobe Acrobat format, aka pdf). To download or print any patent click here.
Patent No.:
Date of Patent:
Feb. 04, 1992
Filed:
Jun. 08, 1990
Shigeru Yamagata, Kohriyama, JP;
Kyoichi Inaki, Kohriyama, JP;
Toshikatu Matsuya, Kohriyama, JP;
Ralf Takke, Hanau, DE;
Stephan Thomas, Grosskrotzenburg, DE;
Heinz Fabian, Hanau, DE;
Shin-Etsu Quartz Products Co., Ltd., Hanau, DE;
Heraeus Quarzglas GmbH, Hanau, DE;
Abstract
The invention relates to lenses, prisms or other optical members which are subjected to high-power ultraviolet light having a wavelength of about 360 nm or less, or ionizing radiation, particularly optical members for use in laser exposure apparatus for lithography, and to blanks for such optical members. The homogeneity of the refractive index distribution and the resistance to optical deterioration when the optical members are exposed for a long period of time to short wavelength ultraviolet light from a laser beam are improved. The optical members are made of high-purity synthetic silica glass material containing at least about 50 wt. ppm of OH groups, and are doped with hydrogen. The refractive index distribution caused by the fictive temperature distribution during heat treatment in the process of producing high-purity silica glass blanks for optical members in accordance with the present invention is offset by the combined refractive index distribution determined by the OH group concentration distribution or by the OH group concentration distribution and the Cl concentration distribution in the glass.