MEASUREMENT OF REFRACTIVE-INDEXES OF HOMOGENEOUS FIBERS WITH REGULAR OR IRREGULAR TRANSVERSE SECTIONS

Seven fibers of different cross-sectional shape are studied interferometrically using multiple-beam Fizeau fringes. These fibers are of circular, rectangular, triangular, trilobal, elliptical, kidney, and dog-bone cross-sectional shapes. The areas enclosed under the interference fringe shift is considered to represent the optical path difference integrated across the fiber. This principal is applied to nylon 6 fibers of trilobal cross-sectional shape. The described method is suitable for the measurement of refractive indices of any fiber with regular or irregular transverse sections. Microinterferograms are given for illustration.