الفهرس 
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Abstract
The main task of this work is the use of two and multiplebeam interferometric techniques for studying the optothermal and optomechanical properties of the optical and polymer fibres. A general introduction and Review of Literature (previous work) on the fibre characterization by interferometric methods are presented in chapter (1). In chapter (2) the description, basic idea and general theoretical considerations of the interferometric techniques (two and multiplebeam interference systems) are presented for the fibre investigation. Also, the basic concepts of automatic fringe analysis for multiplebeam Fizeau fringes in transmission are introduced. Chapter (3) includes the application of multiplebeam Fizeau fringes technique connected with an optothermal device to study the effect of temperature on the optical properties of Philips gradedindex optical fibres. Also the refractive index profile of the optical fibre is measured at different temperatures. Chapter (4) deals with the determination of the intrinsic (maximum observable) birefringence ?nmax at complete orientation of the assembly for polypropylene (PP) and polyethylene (PE) fibres. Also a new approach is suggested for determining the unknown initial value of the draw ratio for given fibres. In chapter (5): an OptoThermoMechanical device (OTM) is designed for fibres characterization with the doublebeam (Pluta) interference microscope. This device enables us to correlate both the mechanical properties and the thermal properties with the optical properties of fibres. This OTM device consists of three parts which are used for; i) Drawing (StressStrain), ii) Cooling and iii) Heating the fibres. In chapter (6): A drawing device, a PC computer and CCD camera with frame grapper are attached with the system for producing multiplebeam Fizeau fringes in transmission is used to optimize the optical properties during the colddrawing of polypropylene (PP) fibres. The step drawing technique for PP fibres is recommended to overcome the deformation difficulties along the fibre axis due to necking during the drawing processes.