Abstract: Hybrid transducer apparatus which is capable of simultaneously or sequentially forming multiple acoustic beams. In one implementation, the hybrid transducer apparatus consists of a relatively thin piezoceramic disk portion having an aspect ratio less than unity as well as a plurality of diced piezoelectric elements with each of these elements having an aspect ratio greater than unity. The resultant hybrid transducer apparatus reduces the multiple spurious frequency responses seen in prior art implementations and thus can be efficiently treated as a piezoelement having a single degree of freedom along its thickness direction. The hybrid transducer apparatus may also be suitable for use in high voltage and/or high power applications via the inclusion of, for example, a heat conductive epoxy that encapsulates the diced piezoelectric elements.

Abstract: Multi frequency piston transducers which are capable of simultaneously or sequentially forming multiple overlaid acoustic beams. In one implementation, a dual frequency piston transducer is disclosed which is capable of simultaneously or sequentially forming two overlaid acoustic beams. The transducer consists of two or more electrically and acoustically independent piston transducers operating at different frequencies that are physically integrated into a single multi-frequency configuration. This single multi-frequency configuration consists of a high frequency aperture disposed within the aperture area of a lower frequency piston transducer. Additionally, multiple dual frequency piston transducers that are incorporated within a single housing are also disclosed that are useful in, for example, ADCP and measurement of vessel/ship speed applications. Methods of manufacturing and using the aforementioned multi frequency piston transducers are also disclosed.