Perfomance Evaluation Of A Singal Crystal Hydrophone

Relaxor single crystals such as PZN-PT and PMN-PT exhibit superior electromechanical properties and are touted as the next-generation materials for future high performance piezo devices. This work describes a new hydrophone made of high-sensitivity PZN-PT single crystal d₃₁ sensing elements. Three such elements are mounted in custom-made housing. A compartment is provided to house the three pre-amplifiers, one for each element. In the current prototype each element has its own input. This allows the directionality of each element to be measured and the possibility of locating the source direction from the combined signals of the three elements. A compact low noise high impedance voltage follower pre-amplifier has been designed which provides 26 dB of gain. The overall sensitivity was measured to be -169 dB re 1 V/muPa. Directionality has been measured to be approximately omni-directional within plusmn1 dB, up to a frequency of 7 kHz.