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:
Mar. 16, 2004
Filed:
Jan. 31, 2001
Nikon Corporation, Tokyo, JP;
Abstract
A projection optical system of the present invention has a first lens group G being positive, a second lens group G being negative, a third lens group G being positive, a fourth lens group G being negative, a fifth lens group G being positive, and a sixth lens group G being positive in the named order from the first object toward the second object, in which the second lens group G comprises an intermediate lens group G between a negative front lens L and a negative rear lens L and in which the intermediate lens group G is arranged to comprise at least a first positive lens being positive, a second lens being negative, a third lens being negative, and a fourth lens being negative in the named order from the first object toward the second object. The present invention involves findings of suitable focal length ranges for the first to the sixth lens groups G to G and an optimum range of an overall focal length of from the second negative lens to the fourth lens with respect to a focal length of the second lens group G .