Design and characterization of variable acoustic field amplitude and focusing ultrasonic transducers

Abstract

Ultrasonic transducers with concentric annular ring electrodes can be used to generate various circularly symmetric acoustic field profiles. These transducers can also electronically simulate a circular phased array and generate a focused ultrasonic beam. A model which predicts the acoustic transducer output for a given scaled voltage input has been developed. Several transducers have been designed using this model. Special attention has been given to the unique case of the two-dimensional radially Gaussian amplitude profile. Fabrication techniques for these transducers have been developed and are discussed. A microprocessor-based data acquisition system is described which will characterize the two-dimensional transducer profile as well as the propagation profile along one radial axis. Example tests of some of these transducers are presented.