Abstract
The development of the use of interferometric techniques in the study of the optical properties of materials encouraged many researchers to work on the derivation and development of the theoretical considerations and the equations used in the calculations of those properties. The form of these equations depends on the technique used and the cross section of the sample, and also on the method of calculating the optical path difference of light across the sample studied. A modified formula to calculate the three-dimensional birefringence distribution of the fiber, without the need to determine the refractive indices of the fiber in the parallel and perpendicular directions, was presented. The phase distribution of the simulated and experiment interferograms was obtained using subfringe integration method. The results obtained from the new method were compared with the calculated results of a well-known method (Z method) and the figures presented showed that the results of the two methods were close to each other.