A Study of Optical Uniformity of Lithium Niobate and Paratellurite Crystals by the Method of Conoscopy

Abstract

An exact equation of the isochromatic fringes of uniaxial crystals derived without usually adopted simplications is presented. It enables to calculate the optical conoscopic gures for ideal crystals with dierent angular orientations of the optical axis with respect to the normal to the crystal surface. Conoscopic gures of large-size single crystals of lithium niobate and paratellurite were examined experimentally making use of a laser-based setup. The conoscopic gure evolution in operating acousto-optic devices was studied.

Laser Conoscopy of Optically Active Crystals

“…The determination of the optical characteristics of optically active crystals is based on the measurement and visual comparison of various optical parameters that influence the appearance of the interference (conoscopic) pattern. Conoscopic (interference) patterns obtained by passing a converging radiation beam through crystal plates placed between the polarizer and the analyzer allow: to determine the location of the optical axis of the crystal [1][2], to determine the presence of optical activity and the sign of rotation of the polarization plane [1][2][3][4][5][6][7][8][9], to determine the optical sign [2,7], as well as to investigate the optical anomalies and the influence of external influences on the crystal [10][11][12][13][14]. Optically active crystals can have two enantiomorphic modifications -right and left.…”