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Information × Registration Number 0221U105867, 0120U104900 , R & D reports Title Experimental-theoretical study and prediction of photoelastic properties of crystalline materials for control devices for electromagnetic radiation popup.stage_title Head Mytsyk Bohdan H., Доктор фізико-математичних наук Registration Date 06-09-2021 Organization Physico-Mechanical Institute named after GV Karpenko of the National Academy of Sciences of Ukraine popup.description2  Characterization of calcium gallogermanate Ca3Ga2Ge4O14 and ammonium fluoroberylate (NH4)2BeF4 crystals was performed. The values of the parameters required for photoelastic studies (elastic coefficients, refractive indices, density, sound velocities, etc.) have been established. Peculiarities of interferometric and polarization-optical methods for measuring the POС of anisotropic crystals are described. A polarization-optical setup for POC measurements by the polarization-optical method and the conoscopy method has been started. An analytical description of POE in crystals of trigonal and rhombic syngony, working formulas for determining POC and proving their reliability are presented. For these crystals, the values of all components of the POC and EOC matrices and the errors of their determination are experimentally determined and given in the tables. The errors in determining the POC were found as the root mean square values of the errors of the experimental values of half-wavelength stresses and the errors of the elastic term. The components of the matrix of elastic-optical coefficients pin are calculated on the basis of POC πim and elastic stiffness coefficients Cmn. High-quality single crystals (NH4)2BeF4 were grown, samples with optimal dimensions of ~ 8 × 8 × 8 mm were made to study their photoelasticity, and plate-like samples were made to determine refractive indices and birefringence of these crystals. The temperature and spectral dependences of the main refractive indices and birefringence of (NH4)2BeF4 crystals were investigated experimentally. The spectral (300.… 700 nm) and temperature (77 .... 300 K) changes of the combined piezo-optic coefficients of (NH4)2BeF4 crystals were determined and it was found that the nature of their anomalies during the phase transitions PT (change of curves slope ºim(Т)) corresponds to the nature of anomalous changes in refractive indices and birefringence at given PT. Product Description popup.authors Demyanyshyn Nataliya M Maksishko Yuliia Ya. Mytsyk Bogdan Grygorovych popup.nrat_date 2021-09-06 Close