Photoelastic Constants of Selected Ultrasonic Delay‐Line Crystals

All of the photoelastic constants of cubic SrTiO3, yttrium gallium garnet, and sapphire, three of the constants of LiNbO3, and all except p44 of rutile have been measured relative to those of fused quartz. The measurements were made at room temperature using 6328 A light. The photoelastic tensor of sapphire is unusual because all of the off‐diagonal components appear to be very small or zero.