Opto-mechanical properties of fibres. 3: Optical properties of Nylon 66 fibres as a function of the draw ratio

Abstract

Refractive indices and birefringence of six samples of nylon 66 fibres having different draw ratios are determined using two-beam and multiple-beam microinterferometry. Four independent techniques have been used for this purpose. The first one used a HeNe laser beam to determine the geometrical parameter of the fibre from its diffraction pattern. The second is the application of the Becke-line method to determine refractive indices and birefringence of the fibre's skin. The third is the application of multiple-beam Fizeau fringes in transmission to determine the mean refractive indices and mean birefringence of these fibres with different draw ratios. Finally, the Pluta polarising interference microscope have been used for determining the mean refractive indices and mean birefringence of these fibres. Relationships between the mean refractive indices, birefringence and polarisabilities per unit volume with draw ratio are given for these fibres. Illustrations are given using microinterferograms.