THE MEASUREMENT OF BACKSCATTER COEFFICIENT FROM A BROAD-BAND PULSE-ECHO SYSTEM - A NEW FORMULATION

A new formulation for obtaining the absolute backscatter coefficient f rom pulse-echo measurements is presented. Using this formulation, perf orming the diffraction correction and system calibration is straightfo rward. The diffraction correction function for the measurement of back scatter coefficient and the acoustic coupling function for a pulse-ech o system are defined. Details of these functions for two very useful c ases are presented: a flat disk transducer and a spherically focused t ransducer. Approximations of these functions are also provided. For a flat disk transducer, the final formulation appears as a modification to the established Sigelmann-Reid formulation. For a focused transduce r, the final correction is a weak function of frequency when the scatt ering volume is near the focal area, rather than the frequency squared dependence proposed by earlier investigators.