Underwater acoustic vector sensor using transverse-response free, shear mode, PMN-PT crystal

Abstract

The present invention is directed to an acoustic vector sensor, also called particle velocity sensor. <111> direction poled, shear mode, relaxor single crystals are used as the sensing elements. In addition, these crystal plates are cut at a special orientation such that they provide zero or minimum responses in the transverse directions, but have a maximum piezoelectric response in sensing direction. The piezoelectric sensor contains a proof mass, a base, and an aforementioned relaxor crystal. Three of the sensors are mounted orthogonally with a rigid case, and they are designated to sense the acoustic particle velocity in three designated directions, say X, Y, and Z. To solve the adverse lateral constraint problem (also known as clamping effect) associated with the relaxor crystal; reduced bonding area between the proof mass and the relaxor crystal are introduced. This feature greatly reduced the percentage of the bonding area for the crystal; consequently the free-state piezoelectric properties of the relaxor crystals are preserved.

Dependencies are inferred from the claim text.