Production of low stress non-(111) oriented large volume single crystals with low stress related birefringence and homogenous refractive index, as well as their application

摘要

Process for preparation especially of a non-111 oriented sliding plane large volume low stress crystal of low double refraction stress and homogeneous refraction index involves growth and tempering of the crystal with stress relaxation along its sliding plane obtained by heat introduction and formation of a temperature gradient, where in tempering the direction of heat input and/or the heat removal in cooling makes an angle with the sliding plane greater than 5 degrees. An independent claim is included for a homogeneous CaF2 crystal of homogeneous refractive index less than 0.025.10 -6 (RMS value), and stress double refraction in the 100-direction of less than 1 nm/cm (PV) and/or less than 0.35 nm/cm (RMS).