EXTENSION OF THE FREEDMAN ECHO FORMATION MODEL TO THE TRANSIENT CASE

This paper presents an extension of a model presented by the same auth ors in the previous CFA [1]. The model allows fast computations of the acoustical impulse-response of the problem of the radiation of ultras onic pulses by realistic transducers, their scattering by immersed tar gets and their reception. In the previous version, the model was restr icted to the case of small targets centered on the transducer axis. He re, it is shown that a more general formula can be derived allowing th e computation of the echo-responses from targets not necessarely cente red on axis which can be of arbitrary size. It is shown that the prese nt model may be considered as an extension to the transient case of th e well-known Freedman's model which derived from a CW theory. Basicall y, the idea is to restrict the computation to the contributions arisin g from the only parts of the target where interferences are constructi ve.