Reflection of Ultrasonic Waves: Phase Shift, Lateral Beam Displacement, and Surface Waves

Abstract

The lateral beam displacement when a finite-width ultrasonic beam is reflected from a plane liquid-solid interface is related to the phase shift upon reflection. In particular, the nongrazing angle of incidence for which the phase shift is 180° is almost equal to that angle of incidence for which the lateral beam displacement is a maximum. It is shown that this same angle also accurately represents that angle at which energy is radiated into the liquid when a surface wave propagates along the interface. Use of these relationships then allows a determination of the velocity of the longitudinal or shear wave in the solid or the longitudinal wave in the liquid when the other two velocities are known and a determination of the velocity of the surface wave from measurements of either the phase shift or the lateral beam displacement upon reflection. [Research done at the University of Tennessee and sponsored by the Office of Naval Research.]