Use of a fibre-optic hydrophone in measuring acoustic parameters of high power hyperthermia transducers

Abstract

A fibre-optic hydrophone consisting of a polarisation-maintaining fibre carrying light from a laser source has been used to measure the acoustic output parameters of a single focused hyperthermia transducer and a six-transducer assembly. Beam profiles of the transducers were measured using the fibre-optic hydrophone and the results compared with those obtained using a PVDF hydrophone. The acoustic power output from the hyperthermia transducer was measured using a radiation force balance. It was observed that the root mean square voltage of the fibre-optic hydrophone output is proportional to the square root of the acoustic power up to more than 80 W. It was also observed that, under continuous-wave operation, the fibre optic hydrophone can stand up to very high power (more than 200 W) without being damaged.