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:
Jun. 01, 1999
Filed:
Nov. 13, 1997
Motoo Koyama, Tokyo, JP;
Nikon Corporation, Tokyo, JP;
Abstract
An optical system for use in an infrared camera which includes, in order from an object side: a first lens group having a negative refractive power and a second lens group having a positive refractive power arranged a distance from the first lens group. The first lens group comprises a negative meniscus lens having a convex surface facing toward the object side and the second lens group comprising, in order from the object side: a first lens having a positive refractive power, a second lens having a negative refractive power and a third lens having a positive refractive power. The lenses comply with the following conditions: (1) 0.5.PHI.<-.PHI.f<0.7.PHI., (2) 0.55.PHI.<.PHI.r<0.87.PHI., (3) 1.55 (1/.PHI.)<d<1.98 (1/.PHI.) and (4) dr<2.1 (1/.PHI.). The conditions are defined by: .PHI.: is the overall refractive power for the overall optical system for the infrared camera, .PHI.f: is the refractive power for the first lens group, .PHI.r: is the refractive power for the second lens group, d: is the distance between principal points of the first and second lens groups and dr: is the lens separation between the most objectwise lens surface and the most imagewise lens surface in the second lens group. The first and second lens groups are made up of lenses which contain silicon or germanium.