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:
Aug. 24, 1999
Filed:
Sep. 11, 1997
Toshihiro Sasaya, Yokohama, JP;
Kazuo Ushida, Tokyo, JP;
Yutaka Suenaga, Yokohama, JP;
Romeo I Mercado, Fremont, CA (US);
Nikon Corporation, , JP;
Abstract
In the projection optical system that projects an image of the first object onto the second object with a fixed reduction ratio and a projection aligner equipped therewith, said projection optical system comprises, viewed from said first object side, in order of succession, the first group of lenses with positive refractive power, and the second group of lenses virtually consists of afocal system, and the third group of lens with positive refractive power, and if the focal length of said projection optical system is represented by F, the projection magnification ratio of said projection optical system is represented by B, the distance between said first object and said second object is represented by L, the distance from said first object to the lens surface that is closest to said first group of lenses is represented by d.sub.0, the focal length of said first group of lenses is represented by f.sub.1, and the focal length of said third group of lenses is represented by f.sub.3 herein, then the following conditions should be satisfied: