Patent ID: 7410463

Claim:
An optical system for a stereoscopic rigid endoscope configured to form a pair of images of an object located at a position facing an insertion unit of the endoscope on a proximal side of the insertion unit, the endoscope comprising: a first objective optical system and a second objective optical system which are provided inside the insertion unit and are located at positions having the same distance from a tip of the insertion unit, the first objective optical system and the second objective optical system having a predetermined clearance therebetween; an optical path combining system that polarizes light passed through the first objective optical system and light passed through the second objective optical system in directions perpendicular to each other, the optical path combining system parallelly shifting the optical axes of the first objective optical system and the second objective optical system by a predetermined amount so as to coincide with each other, an angle formed between a shifting direction of the first objective optical system and a shifting direction of the second objective optical system being equal to or less than 90 degrees; a relaying optical system provided inside the insertion unit and having an optical axis that is coaxial with the optical axes of the first objective optical system and the second objective optical system made coaxial by the optical path combining system, the relaying optical system relaying the image formed by each of the first objective optical system and the second objective optical system from the position in the vicinity of the distal end of the insertion unit to a position in the vicinity of the proximal end of the insertion unit; and an optical image separating system that obtains the image formed with the light passed through the first objective optical system and the image formed with light passed through the second objective optical system separately by separating the light passed through the relaying optical system into a first component that has passed through the first objective optical system and polarized by the optical path combining system and a second component that has passed through the second objective optical system and polarized by the optical path combining system from each other.