Piezooptic coefficient

Much of what has been said above concerning the electrooptic effect also applies mutatis mutandis to the piezooptic effect (variation of refractive index by external mechanical stress). Due to unavoidable dispersion piezooptic coefficients measured by optical techniques can hardly be related to the low-frequency regime for which the definitions of Sect. 6.3 are intended. Determining these constants quasistatically or at sufficiently low frequencies would involve the measurement of permittivity under mechanical stress. Investigations of this type have been made by the group around Newnham and Cross (Uchino et al. (1980), Rittenmyer et al. (1983), Meng and Cross (1985)). 

K. Vedam Piezooptic, Elastooptic Coefficients, 4.36 Landolt-Bbrnstein, New Series 111/30, ed. by... 

The ambiguity of their interpretation has already been pointed out in Sect. 6.3 They could be seen to represent the dependence either of a dielectric coefficient on a mechanical variable (and in this way related to the piezooptic effect) or of a piezoelectric coefficient on an electric variable (and associated with electrostriction). 

Landolt-Bomstein Tables, Neue Serie Vol. III/30a (Editor D.F. Nelson), Springer Verlag. Cook, Jr. WR, Nelson DF, Vedan K (1996) High Frequency Properties of Dielectric Crystals. Piezooptic and Electrooptic Coefficients and Nonlinear Dielectric Susceptibilities. 

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