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:
Feb. 20, 1990
Filed:
Mar. 01, 1989
Keiji Moriyama, Yokohama, JP;
Hiroshi Ohki, Setagaya, JP;
Nikon Corporation, Tokyo, JP;
Abstract
A focus state detecting optical system is provided with a condenser lens positioned in the vicinity of or behind a primary image formed by the light coming from an object and transmitted by an objective lens, pupil dividing means positioned behind the condenser lens and adapted for dividing the pupil of the condenser lens symmetrically with respect to the optical axis, and re-imaging lenses positioned parallel to and corresponding to thus divided pupils and symmetrically with respect to the optical axis thereby forming secondary images, wherein the focus state is detected from the relative positional aberration of said secondary images. Each of the re-imaging lenses is composed of a positive lens with two convex faces of which at least one is an aspherical shape.