Specific properties and optical anisotropy parameters measurements of BaF2 and SrF2 materials

Optical anisotropy parameter of the material determines thermally induced birefringence in the optical element, its dependence on the direction of the crystallographic axes and the feasibility and effectiveness of compensation of thermally induced birefringence. Using the original method, the optical anisotropy parameters of the BaF₂ and SrF₂ materials were measured, which with the experimental accuracy at room temperature coincided and amounted -0.34. Numerical comparisons of the effectiveness of various compensation schemes of thermally induced depolarization depending on the parameter of the optical anisotropy were done.