Experimental approach of the diffraction effect with random phase transducers

The continuous evolution of the estimated attenuation with respect to the distance between the probe and the sample was evaluated on a foam phantom. Results show large changes rapidly occurring because of the diffraction effect. Random phase transducers (RPTs) were then introduced for attenuation estimation. RPT can be partially or totally incoherent. New diffraction-calibration curves show that no diffraction occurs with the RPT, all the more as they are totally incoherent. As a consequence, the attenuation is very stable as a function of the probe-sample distance. These observations were confirmed through in vitro measurements on human placentas