"To a large extent, the studies of the physical properties in optical fibers have been playing an important role during their manufacturing process. In this sense, if we are talking about the refractive index function of the optical fibers is considered indeed one of the most important parameter in the optical fibers area: Thus, the main motivation coming because through refractive index profile can be determined various physical attributives on the optical fibers, such as: mode file profiles, dispersion characteristics, power transmission coefficients optical power carried by modes and so on. In this dissertation is described a method of obtaining refractive index function using a basic experimental arrangement which it works with a well-determined wavelength monochromatic source illumination and thus finally visual fields have been taken by a microscopy system. Several examples of optical fibers have been tested, and the application of the method to measurement the refractive index profile is also discussed in general form. All these techniques are described for static systems where the environmental conditions are almost supposed under control in the laboratory, but we hope all these measurement techniques could be applied to the industry where the environmental conditions are usually harder tested for the optical devices and where it requires a better precision and maybe several different numerical procedures".