Abstract
During the last twenty years, the interest in all areas of ultrasound has increased dramatically. One area which has received much attention is in the assessnent of ultrasonic fields from transducers, particularly since the reporting of significant biological effects from the power levels associated with medical diagnostic machines. Miniature probes or hydrophones have been found to be most suitable for making many of the field measurements required by researchers and technicians. This thesis is concerned with the design, construction and calibration of these hydrophones, specifically those using piezoelectric ceramic as the sensor. A versatile ultrasonic test tank facility under computer control, was designed, developed and subsequently used in the assessnent of the design of hydrophones that were built. The development of constructional techniques and procedures (including element cutting and assessnent, and the use of batch construction), and measurement methods and procedures, allowed the systematic investigation of variables in the hydrophone design to be undertaken. The well characterised hydrophones that resulted, have subsequently been used for a number of investigations (for example the propagation of ultrasound in inhomogeneous materials), which are reported briefly.