Temperature dependence of photo-elastic constants in alkali halides

Abstract

The paper furnishes measurements on the birefringence produced at different temperatures in crystals of NaCl, KCl and KBr when subjected to stress. The results show that the stress-optical coefficients (q 11 -q 12) and q 44 decrease in the case of NaCl almost linearly with temperature while in KCl and KBr they increase with the same. The variation for rock salt is of the order of about 30% over an interval of 300° C. In both KCl and KBr, the variation in (q 11 -q 12) which is about 40% over the same interval of temperature is much greater than inq 44 which is of the order of about 15%. The corresponding strain-optical coefficients are also evaluated and given at each temperature.