Zadorozhna A. Elastooptic and elastic properties of Cs2XY4 (X=Hg, Cd; Y=Cl, Br) and NH4HSeO4 crystals

Photoelastic and elastic effects in Cs2XY4 (X=Hg, Cd; Y=Cl, Br) and NH4HSeO4 crystals are the object. The investigations of elastooptic, elastic properties of Cs2XY4 (X=Hg, Cd; Y=Cl, Br) crystals at the room temperature for estimation of their application in acoustooptical modulators and deflectors; study of acoustic properties of incommensurate dielectrics Cs2XY4 and NH4HSeO4 in a wide temperature and hydrostatic pressures range are the aim. Methods - interferometric, optical-polarization, Obreimov's immersion, spectrophotometric, ultrasonic pulse-echo overlap ones. The piezooptical investigations of Cs2HgCl4 crystals were performed, and their photoelastic coefficients were determined. The acoustooptical parameters of Cs2XY4 crystals were estimated. It is found that in these crystals the isotropic light diffraction is efficient. It is found that Cs2HgCl4 is characterized by a wide transparency range. The possibility for application of Cs2XY4 crystals in acoustooptics was considered. The "pressure-temperature" phase diagrams of Cs2HgCl4 and NH4HSeO4 crystals were investigated. These were explained in a framework of phenomenological theory. Optical materials science and instrumentation are the sphere of application.