An Interpretation of the “Frequency of Least Reflection” at the Rayleigh Angle for a Liquid-Solid Interface

Abstract

Ultrasonic receiver detection of a reflected beam at the Rayleigh angle has resulted in the interpretation of a minimum amplitude for a given material at some frequency called the frequency of least reflection. Recently it has been found that, in general, it is more meaningful to regard the reflection of a finite beam as energy redistribution rather than a reemergence of the beam in the same form as it had on incidence. At low megahertz frequencies, that redistribution ,nay be regarded as consisting of three distinct regions: a specular region, a Rayleigh wave radiation region, and a mutual interaction region of the specular and Rayleigh radiations. This model based on schlieren photographs is used to show that the “frequency of least reflection,” observed with a hydrophone, can be explained in terms of energy redistribution.