All-optical acousto-optic method for determination of photo-elastic constants of optical materials

We report on an all-optical method to determine the photo-elastic constants of optical materials. The two-laser technique is based on a combination of the acousto-optic effect and the laser generation of ultrasound. The laser generated ultrasonic wave produces a Raman-Nath type diffraction. The diffraction effciency is proportional to the photo-elastic constants of the material investigated. The constants are determined by careful analysis of the diffraction signals obtained from a stack comprising an unknown material and a reference material.