Patent ID: 7872810
Filing Date: 2011-01-18
Classification: G02B

Abstract:
1. A light shielding structure of an optical device comprising: an outer annular member and an inner annular member which move relative to each other in an axial direction, said outer annular member being concentrically positioned outside said inner annular member; a small-diameter outer peripheral portion and a large-diameter outer peripheral portion which are formed on said inner annular member at different positions to each other in said axial direction, said large-diameter outer peripheral portion being greater in diameter than said small-diameter outer peripheral portion; and a light shielding ring positioned inside said outer annular member and supported thereby, wherein said light shielding ring creates a clearance with said small-diameter outer peripheral portion of said inner annular member, wherein said light shielding ring and said large-diameter outer peripheral portion of said inner annular member face each other along said axial direction in a ready-to-photograph state of said optical device such that the clearance between said outer annular member and said inner annular member is made light-tight, and wherein said light shielding ring and said small-diameter outer peripheral portion of said inner annular member face each other along substantially an entire range of motion in the axial direction of said outer annular member and said inner annular member between the ready-to-photograph state and a retracted state of said optical device in which said clearance does not need to be made light-tight.