Innovative Undersea Sensors Using Relaxor Piezoelectric Single Crystals

The frequency spectrum of interest for hydrophones used in Naval tactical systems, ocean surveillance systems, or for environmental monitoring is continuing to expand, due to increased interest in passively detecting third-world submarines, merchant shipping, biologics, etc. as well as increased interest in multistatic active sonars. LewTech is proposing that our Phase I and follow-on phases concentrate on adapting the hydrophones used in tactical ASW sensors to use relaxor single-crystal piezoelectric materials rather than the traditionally-used polycrystalline lead-zirconate-titanate (PZT) piezoceramic materials. Hydrophones utilizing relaxor single-crystal ceramics can be designed to increase the sensitivity and bandwidth and reduce the self-noise, due to the improved electromechanical coupling factors, dielectric constant, and the loss tangent. The overall objective is to redesign a current Navy sonobuoy hydrophone, using single-crystal ceramics, and demonstrate improvements in sensitivity, self-noise, and bandwidth capabilities. Phase I will fabricate a prototype hydrophone and perform in-water testing and compare the results to the current hydrophone constructed of piezoelectric ceramic. LewTech has formed a strong team with a major sonobuoy manufacturer, UnderSea Sensor Systems, Inc. (USSI), a wholly-owned company of Ultra Electronics, to support the design and development of a practical, cost effective sensor(s) utilizing relaxor single-crystal ceramics.