Deconvolution techniques for the ultrasonic characterization of biphase heterogeneous media

Many studies show that the amplitude information in ultrasonic echograms obtained from heterogeneous biphase media is only weakly correlated to the material physical properties. The mean spacing between heterogeneities randomly distributed in the first phase medium with applications to the counting of biological cells is evaluated. The mean spacing could be deduced from the autocorrelation of the ultrasonic echoes. However, this function does not adequately describe the properties of a very heterogeneous medium, the obtained signature being severely distorted by the measurement setup impulse response. This calls for a deconvolution method like cepstrum analysis. An algorithm for signal to noise ratio enhancement in the detection of the mean spacing between heterogeneities is presented. Theoretical and experimental results, obtained with a synthetic medium consisting in a variable volume percent water suspension of polystyrene microspheres, are reported