Patent ID: 7907352
Filing Date: 2011-03-15
Classification: G02B

Abstract:
1. An endoscope objective lens comprising, in order from an object side: a negative first lens having a concave surface directed to an image side; a first cemented lens formed by cementing a second lens and a third lens, one of the second and third lenses being positive and, the other being negative; a stop; a positive fourth lens including a flat surface or a surface having a larger absolute value in radius of curvature, directed to the object side; and a second cemented lens formed by cementing a positive fifth lens and a negative sixth lens in order from the object side, the second cemented lens having a positive refractive power as a whole, wherein the endoscope objective lens satisfies the following conditional expressions (1) and (2) where f denotes a focal length of the entire system, Bf denotes an air-equivalent length of a back focal length of the entire system, ν ν R d n