Journal of the acoustical society of america vol:93 issue:5 pages:2688-2699
Theoretically obtained three-dimensional plots showing the behavior of the reflection coefficient for heterogeneous plane waves upon arbitrary layered media as function of incidence angle and heterogeneity, supply valuable information for the investigation of the reflector when using bounded ultrasonic beams. The presence of leaky interface modes and their angular positions for a specific sample are determined by the fd products (frequency times thickness) of the constituent layers. Deformations of the reflected and transmitted bounded beam profiles and the contribution of surface wave radiation (leaking energy) at vibrational mode angles are governed by the f W product (frequency times beamwidth). For a given layered medium, optimum conditions for observing particular mode vibrations and large deformations of reflected ultrasonic profiles can be predicted theoretically.