Lighting device for endoscope

Abstract

Abstract PURPOSE:To increase an observable range and to eliminate exposure unbalance at the periphery of the center of a visual field and the circumference by providing an incident angle optical converting device which decreases the angle of incidence of an incident light beam by a converging means temporarily and then allowing the light beam to strike the incidence end surface of a light guide fiber. CONSTITUTION:A concave lens 22 is arranged as the incident angle converting optical device between a light source lamp 16 and a converging mirror 17, and the incidence end surface 18a of the light guide 18, and a concave lens system 20 is arranged as a projection angle increasing optical device at the side of the projection end surface 18b of the light guide fiber 18. The concave lens system 22 performs the reverse operation of the concave lens system 20, so its focal length is varied freely; and the converging mirror 17 of, for example, theta 30 deg. is used to decrease the angle theta=60 deg. of incidence on a wide-angle lighting optical system which is widened by the concave lens system 20 to theta' 60 deg. to about 30 deg., so the observable range is about three times as long as when theta=60 deg..

Inventors

• 👤 Riyuusuke Adachi
• 👤 安達　滝介

Bibliographic Details