Laser conoscopy of single crystals by radiation with orthogonal polarisations

A comparative study of the conoscopic patterns of lithium niobate and paratellurite single crystals formed by laser radiation with circular, elliptical and linear polarisations having orthogonal forms has been carried out. It is found that two different kinds of conoscopic patterns for each crystal correspond to two orthogonal forms of linear radiation, one kind of conoscopic patterns correspond to two orthogonal forms of circular radiation, and one kind of conoscopic patterns correspond to two orthogonal forms of elliptical radiation. It is shown that for both circular and elliptical radiations, when the direction of rotation of the vector E is reversed, the symmetry axis of the conoscopic image of the crystal is rotated $\sim$ by 90$^\circ$. The results of computer modelling of conoscopic images of crystals with linear and circular radiations, which correlate with the experiment, are given.