Patent ID: 7582057

Claim:
An endoscopic system, comprising: a composite optical fiber consisting essentially of a large-diameter, laser light transmitting optical fiber and a large number of image transmitting fibers that are bundled together to form an integral assembly with a central fiber, the large-diameter optical fiber being surrounded by the image transmitting fibers and the image transmitting optical fibers being fused to form a monolithic sea-island structure in which a large number of cores as islands are surrounded by a continuous phase of a cladding as a sea; a laser treatment and image observing optical unit that is connected to an eyepiece portion of said composite optical fiber such that the unit launches laser light into said large-diameter optical fiber and such that an image being transmitted through said image transmitting optical fiber is focused on a camera to become observable, and an illuminating light transmitting unit that transmits illuminating light to a tip of an objective portion of said composite optical fiber for irradiation purposes, where said illuminating light transmitting unit includes a light source and a light guide that transmits the illuminating light emerging from said light source, at least the tip portion of said light guide being made integral with said image transmitting optical fibers in its longitudinal direction, and wherein said large-diameter, laser light transmitting optical fiber and said image transmitting optical fibers are each an optical fiber having a core and of which a core/cladding index difference Δ is 3.5 to 4%.