PULSE ECHO SINGLE FREQUENCY ACOUSTIC NONLINEARITY PARAMETER (B/A) MEASUREMENT

Pulse-echo single frequency method for B/A measurement is reported. The technique is based on excitation of the medium at a progressively increasing amplitude level and the computing of B/A from the deviation in linearity of the transducer input-output relationship. Starting from the nonlinear wave equation, a three-dimensional (3-D) analytical formulation that predicts the approximate field distribution for finite amplitude waves is derived. This provides the computation for the transducer output voltage for progressively increasing signal levels. It is shown that by a suitable normalization, the effects of the diffraction can be excluded. From a nonlinear least square fit of the experimental data to the analytical equation the B/A is computed. A number of simulations for the model together with preliminary experiments that were carried out at 3.5 MHz are presented. © 1990 IEEE