Patent Number: 6,252,722

Title: Endoscopic objective lens

Abstract: Single homogeneous planoconvex lens 10 having a uniform refractive index is combined with single distributed-index lens 12 having its refractive index distributed in a radial direction and the object plane, the homogeneous planoconvex lens, the distributed-index lens and the image plane are arranged in that order along the optical axis. Both surfaces of the distributed-index lens are planar and the homogeneous planoconvex lens has its convex surface directed toward the distributed-index lens and the planar surface toward the object. Various characteristics of the two lenses are so specified as to provide an angle of view greater than 50.degree..

Inventors: Kittaka; Shigeo (Osaka, JP), Shibayama; Nobuo (Osaka, JP)

Assignee: Nippon Sheet Glass Co., Ltd.

International Classification: G02B 23/24 (20060101); G02B 027/64 (); G02B 003/02 ()

Expiration Date: 06/26/2018