Laser Conoscopy of Crystal Plates with Input Face Parallel to Optical Axis

Manufacturing processes of materials for optoelectronics require the development of control methods to meet material quality standards. Interference methods are invariably relevant for studies of anisotropic optics, are non-contact, can be used for control of significant batches of samples under study. The paper considers the features of interference in divergent beams of radiation for crystal plates in sections parallel to the optical axis of the crystal. The optical system for observing the conoscopic patterns of crystals illuminated by laser radiation makes it possible to gradually change the angle between the optical axes of the crystal plates and the system axis or to fix it in a stationary position, which leads to certain changes in the conoscopic (interference) patterns. By these changes one can judge both the optical characteristics of the crystal, sand the polarization of the radiation. In plates cut from the crystal parallel to the optical axis, the conoscopic pattern is two systems of hyperbolas alternating in intensity (black and light) and located at an angle of 90° to each other. The conoscopic pattern gives a general view of the distribution of radiation intensity when a divergent beam of radiation passes through a crystal plate. The features of changes in conoscopic patterns of optical crystals in sections parallel to the optical axis under the influence of the following factors have been revealed: rotation of the analyzer in the optical system, change of polarization of incoming radiation from linear to circular and elliptical with different direction of rotation of vector E, introduction of stationary and mobile optical compensators in the optical system, observation of conoscopic patterns in systems of several elements in order to develop the methodology of laser conoscopic method of investigation and its applications in a wide range of applied problems.