Determination of the Photoelastic Constants of NaCl, NaF, KCl, and KI by Means of Brillouin Scattering

The photoelastic constants of NaCl, NaF, KCl, and KI have been determined by studying Brillouin scattering at 90° and 180°. The absolute intensities of the Brillouin doublets were obtained by comparing the Brillouin intensity with the intensity scattered by toluene, which has a well-known photoelastic coefficient. The results are NaCl:$p_{11}=0.115\mathrm{}\pm 0.009$, $p_{12}=0.161\mathrm{}\pm 0.008$, $p_{44}=-0.011\mathrm{}\pm 0.001$; NaF:$p_{12}=0.123\mathrm{}\pm 0.009$; KCl:$p_{11}=0.233\mathrm{}\pm 0.013$, $p_{12}=0.169\mathrm{}\pm 0.008$, $p_{44}=-0.026\mathrm{}\pm 0.002$; and KI:$p_{11}=0.208\mathrm{}\pm 0.012$, $p_{12}=0.166\mathrm{}\pm 0.008$, $p_{44}=-0.011\mathrm{}\pm 0.001$.