Joint transform correlator for the detection of defects in optical fibers

A hybrid optical/digital system for detecting defects in optical fibers is proposed. Since the structure of the fibers is the multilayer coaxial cylinder with step indices, the defects in any layer change the spatial frequency spectrum of the fibers and can be detected by comparison with the spectrum of a desired perfect fiber. A joint transform correlator can carry out the detection by continuously updating the test fiber with the desired reference fiber in its stationary position. We show that by joint transform correlator, fiber defects can be successfully detected. (C) 1998 Society of Photo-Optical instrumentation Engineers. [S0091-3286(98)01305-1].