Standard Hydrophone for the Infrasonic and Audio-Frequency Range at Hydrostatic Pressure to 10 000 psig

Abstract

A pressure-sensitive reference hydrophone for the frequency range 0.3 Hz to 20 kHz at hydrostatic pressure to 10 000 psig and temperature from 5° to 35°C has been developed at the Naval Research Laboratory, Underwater Sound Reference Division. The nominal open-circuit crystal sensitivity of the hydrophone is −85.5±0.5 dB re 1 V/μbar from 1 Hz to 15 kHz; the output of the lithium sulfate sensitive element is increased by a transistorized 10-dB-gain (nominal) preamplifier. A novel cable gland improves the high-pressure reliability of the hydrophone.

A micro-machined piezoelectric flexural-mode hydrophone with air backing: Benefit of air backing for enhancing sensitivity

“…7,8 Many hydrophones use piezoelectric bodies as transducers, and fundamental vibration modes ͑e.g., thickness, bending, cylindrical, and spherical modes͒ of a piezoelectric body are commonly used for electromechanical transduction. 9 In recent years, micro-machining technology has been utilized to fabricate various types of hydrophones, from condenser hydrophones to piezo-resistive hydrophones.…”