Tip-sensitive all-silica fiber-optic Fabry–Perot ultrasonic hydrophone for charactering high intensity focused ultrasound fields

This Letter reports on a tip-sensitive all-silica fiber-optic Fabry–Perot (TAFOFP) ultrasonic hydrophone for measuring high intensity focused ultrasound (HIFU) fields. The all-silica fiber-optic structure ensures that the TAFOFP ultrasonic hydrophone can withstand HIFU fields and the tip-sensitive configuration ensures that the TAFOFP ultrasonic hydrophone can achieve a high spatial resolution of 125 μm. The experimental results have shown that the TAFOFP ultrasonic hydrophone could stably measure the peak positive ultrasonic pressure as high as 4.34 MPa, and the measured ultrasonic pressure distributions of the HIFU field by the fabricated TAFOFP ultrasonic hydrophone agreed well with those by the piezoceramic needle hydrophone.