Acoustooptical method of measuring sound velocity in solids

A method of measuring the sound velocity in acoustooptic d y active solids has been investigated. The method is based upon the fact that the velocity can be determined from the frequency difference between two resonant standing-wave modes in an acoustical interferometer. Instead of measuring the transformed acoustical impedance of the interferometer, the energy in the modes is probed with a laser beam, resulting in easy and accurate measurements. The method is applied to measure the sound velocity in germanium, which is the most utilized material in acoustooptical modulators for CO₂-lasers. The velocity of a longitudinal acoustical wave propagation in the [11l]-direction in single crystal germanium was found to be 5481±6 m/s at room temperature.