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:
May. 25, 1999
Filed:
Jul. 25, 1997
Takashi Mori, Kanagawa-ken, JP;
Jin Yamada, Kanagawa-ken, JP;
Jun Nagatsuka, Kanagawa-ken, JP;
Shinichi Hasegawa, Saitama-ken, JP;
Shigeru Hagiwara, Kanagawa-ken, JP;
Nikon Corporation, Tokyo, JP;
Abstract
An optical illumination device reflects and condenses light from a mercury-arc lamp by a light reflecting and condensing member and then reflects and deflects the light, thereafter the reflected and deflected light is transferred to a relay-lens system through a collimator lens or input lens, band-pass filter and fly-eye lens. Gas from which impurities are removed by a filter is flown around optical elements to separate the optical elements from air containing material causing clouding of the optical elements to thereby restrain clouding of the optical elements. On the other hand, or in addition, the reflectance of the light reflecting and condensing member and/or miller for the light of the absorption band of sulfur dioxide is made small to prevent the optical elements from clouding.