Step index fiber using laser interferometer

Abstract

A model is suggested to describe the fringe shift which occurs due to the phase variations of cladded glass fiber introduced between the two plates of the liquid wedge interferometer illuminated with a He–Ne laser. The fringe shift of the phase object which appears in the denominator of the Airy distribution formula of the multiple beam interference is represented in the harmonic term. An experiment is conducted using a liquid wedge interferometer where the step-index glass fiber of a nearly quadratic thickness variation is introduced between the two plates of the interferometer. The obtained fringe shift shows a good agreement with the proposed quadratic model. The Matlab code is written to plot the interferometer fringes comprising the shift of the step-index fiber. Secondly, the recognition of elliptical fibers is outlined using tomographic imaging. Finally, the results and concluding remarks are given