MULTIPLE-BEAM FIZEAU FRINGES CROSSING A FIBER OF TRILOBAL SHAPED CROSS-SECTION

Theoretical and experimental treatments of the shape of Fizeau fringes crossing a fibre of trilobal-shaped cross-section assumed to consist of a single medium are presented. A new mathematical expression is der ived and used to estimate the refractive indices and the birefringence of Perlon (polycaprolactam) fibre. The resulting data are used to cal culate the polarizability per unit volume. Cauchy's dispersion constan ts, the isotropic refractive index and the variation of refractive ind ex with temperature are reported. The results are in agreement with pr eviously published data The data are illustrated by microinterferogram s.