Birefringence dispersion inhomogeneity testing in optical materials by imaging polarimetry

In many optical applications of anisotropic crystals birefringence dispersion (BD) is at least so important as birefringence spatial inhomogeneity itself. In this work a new technique of 2D mapping of parameters related to BD in plane-parallel wafers of optical materials is reported. A computer-controlled imaging spectro-polarimeter is used for recording the wafers' images for consecutively varying wavelengths. Examples of practical measurements carried out on undoped and Cu-doped LiNbO3 are presented.