Ellipticity measurement of optical fibers.

The experimental aspects of a sensitive, nondestructive, and noncontacting method to measure the noncir-cularity of dielectric cylinders are presented. The technique makes use of the variation in the position of a fringe in the backscattered light arising from a beam that is incident at right angles to the cylinders axis, as the cylinder is rotated. The method has been applied to optical fibers, and ellipticities as small as 0.997 have been measured. The results are in agreement with photomicroscopy measurements and with theoretical predictions.