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:
Sep. 16, 1997
Filed:
Jun. 01, 1995
Yutaka Suenaga, Yokohama, JP;
Toshiro Ishiyama, Kawasaki, JP;
Yoshiyuki Shimizu, Miura, JP;
Kiyoshi Hayashi, Koganei, JP;
Nikon Corporation, Tokyo, JP;
Abstract
A first partial optical system including a first group of lenses having a positive refractive power, a first concave reflection mirror and a second group of lenses having a positive refractive power, for forming a primary reduced image of an object, a second partial optical system including a second concave reelection mirror and a third group of lenses having a positive refractive power, for further reducing the primary reduced image and refocusing it, and a reflection mirror arranged between the first partial optical system and the second partial optical system, for deflecting a light path are arranged in a sequence as viewed from the object. A good image-forming ability as a projection optical system for fabricating a semiconductor device is attained with a simple construction.