Patent ID: 9182585
Filing Date: 2015-11-10
Classification: A61B,G02B

Abstract:
1. An endoscope objective lens comprising: in sequence from an object side, a front group having negative refractive power, an aperture stop, and a rear group having positive refractive power; and a focusing lens that has negative refractive power and that can be inserted into or retracted from an optical path between the front group and the rear group, wherein the focusing lens is inserted into the optical path in a normal observation state and is retracted from the optical path in a short-distance observation state, in which the working distance is smaller than that in the normal observation state, and wherein Conditional Expressions (1), (2) and (3) below are satisfied: where fc is a focal length of the focusing lens, FL is a focal length of the entire endoscope objective lens in the normal observation state, ra is a radius of curvature of an object-side surface of the focusing lens, and rb is a radius of curvature of an image-side surface of the focusing lens.