@Article{, title={Temperature-Dependent Birefringence Properties of Be3Al2Si6O18 Crystal}, author={M.A. Albarazanchy and I.K. Hama and G.M. Najeeb}, journal={Iraqi Journal of Applied Physics Letters مجلة الرسائل العراقية في الفيزياء التطبيقية}, volume={2}, number={1}, pages={12-14}, year={2009}, abstract={The temperature dependence of the refractive indices for ordinary and extraordinary rays of mercury spectrum three lines and laser line independently one from the other were measured in temperature interval 20-600°C. It was obtained that the refractive indices increase along with the temperature growth and this dependence has quasilinear character. Emerald has quite low birefringence values that increases slightly along with the temperature growth and decreases with wavelength growth. The thermooptical coefficients for every wavelength were calculated. They have greater values for the extraordinary beams than for the ordinary ones. The dispersion curve for refractive indices was obtained.

} }