Relationship between acoustic cavitation bubble behavior and output signal from tough hydrophone using high-speed camera in high-frequency and low-frequency acoustic fields

In previous works, our developed tough hydrophone was resistant to high-pressure fields (15 MPa). During the experiment, acoustic cavitation bubbles were generated around the tough hydrophone tip, because the tip was slightly larger than the wavelength and was flat. In this study, the influence of the tough hydrophone on high-intensity 1MHz and 22 kHz acoustic fields was investigated by visualizing bubbles around the hydrophone and recording the waveform from the hydrophone at the same time. As a result, the hydrophone with a flat tip can be used for measurements in 1MHz and 22 kHz high-intensity acoustic fields under certain conditions where acoustic bubble cloud generation on the hydrophone tip is avoided. The change in output waveforms from the hydrophone was negligibly small, even when collision and sticking of the acoustic bubble to the hydrophone tip occurred. (C) 2018 The Japan Society of Applied Physics