Color enhanced historic image (circa 1968) of a group of optical fibers gathered together at one end and inserted into a light source. The light is transmitted through each of these .003 inch diameter fibers by the phenomenon of total internal reflection. The light is transmitted through a core which is drawn from high quality optical glass. This core is clad with a glass which has a lower index of reflection. In simple terms, the cladding keeps the light inside the core material multiple reflection.