Detection of the variation of the optical and geometrical parameters of fibres due to the cold drawing process

A method is described to detect the variation of the refractive index profile, transverse sectional shapes, areas and mechanical properties of fibres during the cold drawing process. A rotator-mechanical drawing device is used for rotating the fibre around its longitudinal axis during the cold drawing process for the fibre from the two fixed ends. In this method, the rotator-mechanical drawing device is attached with a Pluta polarizing interference microscope for detecting the variation of the geometrical dimensions of fibres in front of the interferometer. The suggested method permits determining the refractive index profile of the drawn fibres taking into consideration the transverse sectional area and the enclosed area under the fringe shift. Nylon 6 and polypropylene fibres are used in this investigation. The optical orientation factor and orientation angle are calculated for these fibres to clarify the orientation of molecules due to the cold drawing process. Microinterferograms are given for illustration.