Some approximate relations in the photoelasticity of strongly anisotropic crystals

Abstract

The knowledge of the principal refractive indices and their dependence on the applied stress is the starting point for any experimental analysis of transparent crystals. Because for strongly anisotropic crystals and a general state of stress an explicit analytical solution can be difficult to obtain, then we need some approximated solutions. Here, we propose a coherent approximation procedure that generalizes results already obtained and give a simple example of application.

Elasto-optic properties and internal stress analysis for monoclinic and trigonal crystals

“…briefly recall an approximated technique proposed into [27] which allows to obtain an approximate expression for eigenvalues and eigenvectors provided some conditions are verified. A different, more general and coherent approach was proposed into [48], where the present approximation is recovered as a special and less general case. We begin with assuming that the eigenvectors u 𝑖 and eigenvalue 𝑆 𝑖 of a symmetric Tensor S are known: then we add another symmetric tensor 𝜁 to S and consider first the case of three different eigenvalues.…”

Effect of supersaturation on structural stress of rapidly growing KDP crystals studied by wide-angle conoscopic interference

“…[20][21][22] However, for crystals belonging to lower symmetry crystal systems such as trigonal, tetragonal, and hexagonal systems, the birefringence caused by optical anisotropy of these crystals makes this method useless. 23 Therefore, this paper explores the photoelastic effect of KDP crystals to develop a method for measuring structural stress of uniaxial KDP crystals. This is achieved by analyzing the relationship between crystal shear stress and fringe spacing in wide-angle conoscopic interference.…”