Image and light conducting optical fibre bundle - has reticulated covering on each individual core to increase internal reflection by providing numerous reflecting surfaces

摘要

The cover (24) of each individual core (23) is made of crown glass and is so formed to have a finely reticulated surface consisting of numerous projections (27) and depressions (26). When a light beam (I1) enters the end of a fibre (25) and arrives at the boundary (29) between core (23) and cover (24) with an angle of incidence which is not smaller than the critical angle for core (23) and cover (24), total internal reflection takes place and the light beam (I1) finally emerges from the other end of the core (23). When a light beam (I2) enters at an angle which is less than the critical angle it is partly reflected at the boundary (29) and partly enters the covering (24) as (I3) where it strikes the reticulated surface (25) and is reflected (I4) back into the core (23). Reflectivity between the cores is lessened without significantly increasing their external diameters thus has advantages for use in endoscopes.