BERGMANN METHOD FOR MEASUREMENT OF VELOCITIES OF BODY AND SURFACE ELASTIC WAVES.

A procedure is developed for measurement of the velocities of body and surface acoustic waves in transparent bodies at frequencies of 8-11 MHz that combines the Bergmann method of light diffraction by ultrasound with a resonance method. The procedure combines the clarity of the results of studies of elastic symmetry of crystals with precision (accuracy of approximately 10** minus **4-10** minus **5 m/sec) measurement of the velocities of body and surface acoustic waves in any direction on elastic diffraction patterns and provides a complete matrix of elastic coefficient from only one specimen. The method is convenient for study of the effect of temperature, pressure, and other external factors on sound velocity and can be also used to study nonlinear effects and to estimate the acoustooptical quality of crystals from diffraction patterns.