Abstract
In this paper, an accurate and efficient method for measuring the refractive index of a transparent plate is developed. The refractive index is evaluated by using Fourier Transform Method (FTM), from a fringe pattern generated by digital speckle photography. The validity and accuracy of the method were confirmed with a standard reference material. Furthermore, the method is insensitive to environmental perturbations, and simple to implement, compared to the conventional index measurement methods providing similar accuracy.