Patent ID: 9140888
Filing Date: 2015-09-22
Classification: G02B

Abstract:
1. An objective lens for an endoscope, comprising: a first lens group having a negative power; an aperture stop; and a second lens group having a positive power, wherein the first lens group, the aperture stop and the second lens group are arranged in this order from an object side, wherein: the first lens group comprises at least a negative front group lens having a concave surface facing an image side, and a positive front group lens having a convex surface facing the image side, the negative front group lens and the positive front group lens being arranged in this order from the object side; the second lens group comprises at least a positive rear group lens having a convex surface facing the image side and a cemented lens formed by cementing together a negative lens and a positive lens, the positive rear group lens and the cemented lens being arranged in this order from the object side; and when a focal length of the first lens group is defined as f where SF=(R