Infrared light transmission fiber

Claim 1

An infrared light transmission fiber comprising: a single optical fiber made of an infrared light transmitting material, said material being selected from (1) silver halide or a mixture of silver halides, (2) thallium halide or a mixture of thallium halides, (3) alkali metal halides or alkaline earth metal halides, or mixtures thereof, (4) a chalcogenide, (5) a mixture of (a) silver halides and mixtures thereof, (b) thallium halides and mixtures thereof, and (c) alkali metal halides or alkaline earth metal halides, or mixtures thereof, a primary coating of a cured thermosetting resin which covers the outer surface of said single optical fiber, said primary resin consisting essentially of a resin selected from the group consisting of polyester imide, polyimide, polyamide-amide, polyester, polyurethane or polyvinyl formal, and a reinforcing layer covering only said primary coating of said single optical fiber and consisting essentially of glass fibers impregnated with a thermosetting resin which is cured after impregnation, said resin of the reinforcing layer being the same as the resin for the primary coating.