Interferometric determination of optical anisotropy in fibers. II. Fibers with a skin‐core structure

The polarizing interference microscope with a modified method is used to determine the refractive indices and birefringence of both layers of fibers having a skin‐core structure. This method is applied to nylon 6 and polyester fibers. Two fibers are used for each measurement. The first fiber is of known mean refractive index and dispersion properties. The other fiber is of unknown values of refractive indices of each layer of the fiber. This method can be used for fibers with regular or irregular cross sections. In the latter case the area enclosed under the interference fringe shift represents the optical path difference integrated across the fiber. The obtained results of refractive indices and birefringence are compared with those obtained from the normal method and found to be in good agreement. Illustrations are given by microinterferograms.