Ultrasonic nonspecular reflectivity near longitudinal critical angle

A numerical integration method is developed to determine the intensity profile of an ultrasonic beam reflected from a liquid-solid interface near the longitudinal critical angle. The profiles are calculated for different combinations of frequencies and beam widths with the angle of incidence being varied about the longitudinal critical angle for a water-Plexiglas interface. These calculations demonstrate the existence of nonspecular reflectivity near this particular critical angle and provide a quantitative description of its basic features. Theoretical results and experimental measurements are compared.