Characterization of uniaxial crystals through the study of fringe patterns

The fringe pattern obtained when a divergent (or convergent) beam goes through a sample of birefringent crystal between two polarizers contains information which is inherent of the crystalline sample under study. On the other hand, by considering the design details of the experience and the parameters that are characteristic of the uniaxial plate, it is possible to theoretically obtain the luminous intensity corresponding to each point on a screen or CCD. Thus, this theoretical model allows us to obtain, from images experimentally obtained and theoretical expressions, the parameters that are characteristic of the plates. The results obtained proved the concordance between theory and experience while endorsing this technique for the characterization of birrefringent crystals and devices based on this type of materials.