Factors in the design of ultrasonic probes

This paper attempts to demonstrate the comprehensive way in which the Unit Impulse Response technique can be used to evaluate and calibrate thickness mode piezoelectric transducers and the ultrasonic probes made from these transducers. Two commonly used piezoelectric materials were compared in the form of batches of disc transducers at several different frequencies and diameters.At higher system gains spurious signals associated with transverse mode resonances seriously reduced the discrimination of the probe. These spurious effects were fully investigated and explained.The effects of backing; quarter-wavelength matching into water; and electrical tuning, were measured and explained.Other methods of measuring the transducer parameters based on frequency response analysis were considered.