Title: THE REFRACTOMETRY OF THE UNIAXIALLY STRESSED FERROELECTRICS
Author(s): M.O.Romanyuk, V.Yo.Stadnyk (The Ivan Franko State University of Lviv, 8 Kyryla and Mefodiya Str., 79005 Lviv, Ukraine)

The effect of uniaxial mechanical stresses upon the spectral and temperature dependences of birefringences in some ferroelectric crystals with the incommensurate phase are studied. Considerable baric displacements of para-incommensurate-commensurate phases transition points were observed.The calculated temperature and spectral dependences of combined $\pi_{im}^0$ and absolute $\pi_{im}$ piezooptic constants show a considerable dispersion and anomalies at phase transitions.The increase of the principal refractive indices under stress effect was observed.

Comments: Figs. 5, Refs. 12, Tabs. 2.