Temperature measurement using optical sensors based on birefringent crystals

Abstract

The conducted studies made it possible to substantiate and practically implement a polarization-optical method of temperature measurement, based on the phenomenon of temperature-induced changes in the birefringence of optically anisotropic crystals. The practical implementation of the method using plates of leucosapphire and lithium niobate as active elements of thermometers has shown that the application of leucosapphire is more preferable due to the wide temperature range of material usage, its mechanical and chemical resistance, and the absence of phase transitions. Lithium niobate has such disadvantages as nonlinearity of the calibration dependence and the presence of a phase transition point; however, despite this, its use allows increasing the sensitivity of the thermometer and improving measurement accuracy.