Fiber optic device having some fibers clad with absorbing glasses

Claim 1

A fiber optic device of the type which is adapted to receive and conduct segments of a light image, said fiber optic device comprising a plurality of light-conducting optical fibers secured together in side-by-side relation so that corresponding opposite ends of the fibers cooperate to define end faces, each of said fibers consisting of a core of light transmissive material of a relatively high index of refraction and a single cladding of light transmissive material of relatively low index of refraction, the core and cladding of each of said fibers forming an internally reflective interface to first light rays of said light image entering one of said faces and incident upon said interface at angles greater than the critical angle of reflection of said interface, said interface being transmissive to second light rays of said light image entering one of said faces and incident upon said interface at angles lesS than said critical angle of reflection, said second light rays passing through said cladding into adjacent fibers, the cladding material of a plurality of said fibers having a relatively low absorption coefficient so that said first light rays are transmitted through said plurality of fibers with substantially no attenuation due to reflection at the core-cladding interfaces thereof, the absorption coefficient of the cladding material of said plurality of fibers being such that said second light rays pass therethrough substantially unattenuated, the cladding material of the remainder of said fibers having an absorption coefficient greater than that of the cladding material of said plurality of fibers so that said first light rays encounter losses on each reflection at the core-cladding interface thereof, said second light rays being attenuated as they pass through the cladding of said remainder of said fibers, said plurality of fibers and said remainder of said fibers having substantially the same crosssectional area and shape, said remainder of said fibers being uniformly dispersed throughout said device, each of said fibers having at least three elongated sidewall surface portions, each of the surface portions of each of said plurality of fibers being disposed adjacent to a surface portion of one of said remainder of said fibers so that a surface portion of absorbing cladding material is always adjacent to a surface portion of non-absorbing cladding material.