The main assumption in this work is that both manual and automatic fringe analysis are used to analyze the multiple-beam Fizeau fringe. A general introduction to fiber, multiple-beam Fizeau fringe, and automatic fringe analysis are presented in chapter 1. Previous work on fiber investigation by interferometric method and previous work on image analysis techniques used to analyze the interference fringe are presented in chapter 2.Chapter 3 deals with in detail the theoretical consideration of multiple-beam Fizeau fringe technique such as conditions of fringe formation. The mathematical expression of refractive index profile for multilayer fiber using multiple-beam Fizeau interferometer and the basic concepts of image processing and image analysis are presented in this chapter.In chapters 4,5 and 6, the interference fringe shift in the fiber region has been analyzed automatically using different techniques of automatic fringe analysis. Plane polarized light vibrating parallel and perpendicular to the fiber axis are used to obtain the refractive index profiles of both cases and some optical properties of fiber.