The double-sided ultrasonic beam displacement

It is a well-established idea in optics as well as in ultrasonics that a bounded Gaussian beam, when reflected from an interface, can be displaced in the forward or in the backward direction, depending on the propagation direction of leaky waves that are generated by the incident beam. Such a displacement is often accompanied by the so-called Schoch effect characterized by a null strip in between a specular and a nonspecular reflected beam, and a trailing field that is much further displaced. The current letter shows experimentally and numerically that a simultaneous forward and backward displacement is possible accompanied by two null strips and being only the result of forward propagating Lamb waves. (C) 2004 American Institute of Physics.