Circular ultrasonic transducer characterization:: theoretical and experimental results

Acoustic pressure fields generated by pulsed ultrasonic transducers under different boundary conditions are analyzed. Numerical simulations of the near-field pressure were evaluated considering rigid and soft baffles as boundary conditions. These field simulations were performed using the temporal convolution between the numerical derivative of the impulse response and the longitudinal wave velocity for both cases. Experimental pressure data were obtained by measuring the peak, peak to peak and root mean squared voltages. Simulated and experimental results, were compared to investigate the temporal behavior of the acoustic signal as well as their spatial distribution on planes parallel to the transducer face. Special attention is given to the Fresnel region where the diffraction effect affects the pressure field measurements. Experimental readings were done using circular transducers with the same geometric characteristics and with resonant frequencies of 3.5 MHz and 5 MHz.