IMPULSE-RESPONSE METHOD TO PREDICT ECHO RESPONSES FROM TARGETS OF COMPLEX-GEOMETRY .2. COMPUTER IMPLEMENTATION AND EXPERIMENTAL VALIDATION

A theoretical model has been proposed for the complete solution of the problem of the radiation of transient ultrasonic pulses, their scattering by targets of complex shape and arbitrary acoustic impedance, and their reception [A. Lhemery, ''Impulse-response method to predict echo responses from targets of complex geometry. Part I: Theory,'' J. Acoust. Sec. Am, 90, 2799-2807 (1991)]. Here, its computer implementation and its experimental validation are considered. First, the theoretical formulation is derived in a discrete form and an algorithm is explicitly given to allow its computer implementation. Precautions to be taken to ensure good precision of numerical results are discussed in detail. Then, predicted waveforms are compared with existing measurements (scattering by planar targets) and new measurements (scattering by nonplanar targets). The model is shown accurately to predict measured echoes, both qualitatively and quantitatively. However, some discrepancies are observed and explained as resulting from the lack of precision in the Kirchhoff-like approximation made in the model's derivation.