Patent ID: 9645383
Date: 2017-05-09
CPC Classifications: G02B

Claim:
1. An objective lens for an endoscope consisting of, in order from the object side, a front group having negative refractive power, an aperture stop and a rear group having positive refractive power, wherein the front group consists of, in order from the object side, a first lens having negative refractive power and a first cemented lens consisting of, in order from the object side, a second lens having negative refractive power and a third lens having positive refractive power cemented together, and wherein the rear group consists of, in order from the object side, a fourth lens having positive refractive power and a second cemented lens consisting of, in order from the object side, a fifth lens having positive refractive power and a sixth lens having negative refractive power cemented together, and wherein the following conditional expressions (1) and (2) are satisfied: f: a focal length of an entire system, fA: a focal length of the front group, νd2: an Abbe number of the second lens for d-line, and νd3: an Abbe number of the third lens for d-line.