A critical component of an ultrasonic system is the transducer. This device converts electrical energy into sound energy and vice versa. In underwater systems, the material used for transducers is usually a lead-zirconate-titanate ceramic mixture that is formed under heat and pressure into some particular shape. In practice, the ceramic has metallic electrodes plated onto two sides and the whole element is raised to above the Curie temperature in an oil bath. Then, a high voltage is applied across the electrodes, causing some of the electrical domains in the crystals to align with the applied external electric field. Letting the ceramic then cool back to room temperature -- with the voltage still applied -- can force some of these domains to remain aligned. The resulting property of the "poled" ceramic is called the piezoelectric effect.

Applying a voltage to a poled ceramic element will cause it to expand or contract, depending upon the polarity of the voltage. Compressing or expanding the element will cause a small electrical charge to accumulate on the electrodes; passing this charge through an external impedance will produce a voltage. Thus, the ceramic element is a transducer of force and voltage.

What I intend to accumulate here is data on building transducers, particularly like those used in TAPS; tuning these transducers for maximum power output and/or bandwidth; and calibrating these transducers.