Illuminating optical system for endoscopes

摘要

An illuminating optical system for endoscopes wherein, in order to make it possible to effect a uniform illumination with a simple structure and without using a mechanical mechanism, a liquid crystal device or electrochromic device is arranged between the entrance end of a light guide and a light source. The transmittance of the light in the part of the liquid crystal device or electrochromic device corresponding to the part brighter than a predetermined value is reduced on the image of an object to be observed. The light guide is formed of many optical fibers or graded index optical fibers arranged to substantially correspond at the entrance end and exit end of the light guide.