Patent ID: 8684915
Filing Date: 2014-04-01
Classification: A61B,G02B

Abstract:
1. An endoscope optical system comprising a negative lens that focuses light entering along an incident optical axis, a first prism that deflects and emits the light that has been focused by the negative lens in a direction along a first axis substantially orthogonal to the incident optical axis, a second prism that has a first reflecting surface, which deflects the light emitted from the first prism in a direction of a second axis substantially orthogonal to the first axis, and a second reflecting surface that deflects and emits the light, which has been deflected in the direction of the second axis, in a returning direction substantially parallel to the first axis, and that is disposed so as to face the first prism, a third prism that deflects the light, which has been emitted from the second prism, in a direction substantially parallel to the incident optical axis, and a positive lens that focuses the light emitted from the third prism, in this order from an object side, wherein the negative lens and the first prism are provided so as to be rotatable about the first axis relative to the second prism, and wherein refractive indices of the first prism, the second prism, and the third prism satisfy the following conditional expression where Np 1 is a d-line refractive index of the first prism, Np 2 is a d-line refractive index of the second prism, and Np 3 is a d-line refractive index of the third prism.