This paper presents a theoretical model based on wave mechanics for the reflection of focused and parallel ultrasonic beams from a liquid-solid interface. The incident beam is defined by a Gaussian velocity distribution along a plane emitter, and the reflected beam is described through its pressure field by means of asymptotic analysis based on the short wave hypothesis. In the case of a focused reflected beam, nonspecular phenomena are observed for any angle of incidence. However, in the case of a parallel reflected beam, nonspecular reflection only occurs if the incidence of the beam is in the neighborhood of the Rayleigh angle. The objective of this paper is to discuss in detail the physical mechanisms of nonspecular reflection for both focused and unfocused beams and to provide an understanding of the complex phenomena related to nonspecular reflection of ultrasonic beams, which plays an important role in scanning acustic microscopy for materials nondestructive characterization. [References: 13]
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