Measurement of refractive indices of fibers with regular or irregular transverse sections and having a skin‐core structure

Abstract

Multiple‐beam Fizeau fringes crossing fibers of different cross‐sectional shapes and having a skin‐core structure are studied to determine the refractive indices of the two layers. These fibers are of circular, rectangular, triangular, trilobal, elliptical, kidney, and dog‐bone cross‐sectional shapes. The area enclosed under the fringe shift is considered to represent the optical path difference integrated across the fiber. This method is suitable for the measurement of refractive indices of fibers of regular or irregular transverse sections. This method is applied to nylon 6 fibers.