face 18 of the sleeve 3 such a lens may be manufactured with a combination of convex concave or flat surfaces in the example of fig4 a a plano concave lens is shown fig5 shows an alternative embodiment of the present invention consisting of a sleeve 3 39 of optically clear flexible plastic 20 encased on its outer 21 and inner 22 surfaces by a thin layer of silicone cladding or opaque non toxic plastic capsule with a low index of refraction or by a reflective coating such as polytetrafluorethylene which enhances the optical transmission of the fiber optic sleeve in this embodiment the fiber optic bundles 15 are omitted because the entire sleeve 3 39 serves as an optical waveguide as indicated in fig5 b the couplers 19 39 of which two are shown are regularly spaced about the periphery and serve to couple the fiber optic bundles from a light source not shown into the optically clear plastic 20 for transmission of light to the tip end 5 alternatively a diffusing collar may be provided interposed between the light cable s and the sleeve 3 39 preferably the end face at the tip end 5 of the sleeve 3 39 should be beveled or angled inwardly so that the light emanating from the end face is directed at an angle radially inward toward the centerline of the embodiment this is represented schematically in the enlarged schematic view of fig5 a which shows the end of the.