Although there are many techniques for performing phase calibration on ultrasound
transducers, most of these suffer from high cost, complexity, or inaccuracy. In the
present work, phase calibration on receive was achieved by the generation of inertial
cavitation emissions in 3% agar gel using a 1 MHz HIFU transducer, the inertial cavitation
emissions providing impulse-like sources for the transducer under calibration. Phase
calibration was performed on a custom-built 5-15 MHz transducer, where the results
showed good agreement with predictions obtained using the KLM transducer model (<5°
difference for 3.0-10.5 MHz, where SNR was above 54 dB and the harmonics of the HIFU
excitation cause limited interference). Phase calibration was also performed on an
element of a commercial 5-10 MHz linear array. In this instance, a KLM model was not
available, so the array element response was modeled as a pole-zero resonator. The
slope of phase with log-frequency that was thus obtained was consistent with the bandwidth
of the array element response. The results demonstrate the potential of cavitation-based
phase calibration on receive to offer higher accuracies than existing phase calibration
methods. Future work will investigate the use of laser cavitation in water to minimize
attenuation and make the method applicable at higher (>10 MHz) frequencies, as well
as remove lowerfrequency (<3 MHz) interference arising from the use of acoustic excitation
to generate cavitation.
