Enhanced interferometric technique for non-destructive characterization of crystalline optical materials: automated express refractive index measurements

We report an enhanced experimental set-up that allows fast and accurate determination of refractive indexes in optical materials. The set-up is equipped with the high-precision sample positioning system and sensitive detector for the registration of interference fringes shift. Additionally, an approach that can be utilized in order to eliminate the error caused by non-parallel sample edges is discussed. The results of the refraction index measurements in lithium niobate are presented.