REFRACTIVE-INDEX DISTRIBUTION IN GRADIENT-INDEX FIBERS, STUDIED BY MEANS OF SHEARING INTERFEROMETRY

The errors of the method of thin-section interferometry, designed for the measurement of the refractive-index distribution (RID) in gradient -index fibers (with a refractive-index deviation of Delta n = 0.1-0.01 and a refractive-index-gradient depth of R = 0.3-3 mm, which are used in practice), have been analyzed. It is shown that, when Delta n is c lose to 0.1, the accuracy of the method is inadequate for monitoring t he aberration characteristics of gradient-index fibers. To enhance the accuracy of the RID measurement, an analysis of the error of the RID- measurement method in gradient-index fibers is proposed, experimentall y tested, and carried out, using a polarization shearing interferomete r constructed on a Savart plate.