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:
Jan. 02, 2001
Filed:
May. 04, 1999
Teruyoshi Tsunashima, Tokyo, JP;
Nikon Corporation, Tokyo, JP;
Abstract
A catadioptric lens (,) comprising, along an optical axis (AX), a first lens group (L,) having an objectwise concave annular incident surface (SI) upon which light from an object is first incident, and a most imagewise lens surface (,). The catadioptric lens further includes an annular main mirror (MM) arranged imagewise of the first lens group and having an objectwise concave reflective surface (R,) that reflects light objectwise. A secondary mirror (MS) is located objectwise of the annular main mirror and has an imagewise convex reflective surface (R,) that reflects light imagewise. The first lens group has a glass optical path from the incident surface to the main mirror to the secondary mirror and to the most imagewise lens surface of the first lens group. The catadioptric lens may also include a second lens group L,imagewise of the first lens group. The second lens group may include two or more lenses, and preferably includes a cemented doublet (L,, L,). The catadioptric lens also preferably satisfies one or more of a number of design conditions.