Detection of geometric perturbations in optical fibers

A sensitive, quick, and nondestructive method to assess the short range geometrical uniformity of optical fibers is presented. The technique is based on an analysis of the backscattered light arising from a beam that is incident at right angles to the fibers axis and is capable of measuring diameter variations on the order of 0.1 microm. Geometric perturbations arising in selected fibers pulled with oxy-hydrogen torch, electric furnace, and CO(2)-laser techniques are shown in an almost instantly read snapshotlike form. The production and detection of intentionally introduced short range diameter variations are also demonstrated.