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:$p_{11}=0.208\mathrm{}\pm 0.012$, $p_{12}=0.166\mathrm{}\pm 0.008$, $p_{44}=-0.011\mathrm{}\pm 0.001$.

• Received 11 June 1973

DOI:https://doi.org/10.1103/PhysRevB.8.5888