Connecting optical system for light guides

Claim 1

An optical system for connecting light guides for endoscopes comprising a first light guide which is arranged on the side of the light source and functions to transmit rays from said light source, a second light guide which receives the rays transmitted through said first light guide and which emerge from the emerging end surface thereof, transmits said rays and allows said rays to emerge from the emerging end surface of said second light guides for illuminating an object, and a lens system arranged between said first and second light guides; the emerging end surface of said first light guide being arranged in the vicinity of the front focal point of said lens system, the incidence end surface of said second light guide being arranged in the vicinity of the rear focal point of said lens system with the diameter of the end surface of said first light guide being larger than that of the incidence end surface of said second light guide; and said optical system being so designed as to satisfy the following condition: ##EQU4## wherein the reference symbol r 1 represents radius of the emerging end surface of said first light guide and the reference symbol F designates focal length of said lens system.