Determination of refractive index profile of partially and highly oriented fibers using double refracting interference microscopy

摘要

Double refracting polarizing interference microscope designed by Pluta is used with a suggested method to determine the refractive index profile and birefringence profile of partially and highly oriented fibers. The application of this method depends on using Pluta polarizing interference microscope in two positions (crossed position for the duplicated images and subtractive position for the non-duplicated image of the fiber). The mathematical representation of the suggested method is given. The refraction of the light beam inside the fibers is taken into consideration while measuring the fringe shift profile. The refractive index profiles of polypropylene fiber with draw ratio 3.5 are determined using the conventional method. The results are compared with those obtained with the suggested method and found to be in good agreement. The suggested method is applied to determine the refractive index profile of poly(aryl ether ether ketone) partially oriented fiber and poly(ethylene terephthalate) highly oriented fiber. The diffraction of He-Ne laser beam is used to determine the average diameters of these fibers. Microinterferograms are given for illustration. (C) 2003 Wiley Periodicals, Inc. J Appl Polyrn Sci 87: 2341-2347,2003. [References: 18]