Broadband operation of acoustic collimated beam source

Abstract

A low-frequency acoustic collimated beam (ACCObeam) source was recently developed by our team using the radial mode excitation of a piezoelectric disc. It relies on lateral clamping of the piezoelectric disc to produce a collimated sound beam while minimizing unwanted side lobes that occur for a free disc. ACCObeam has previously been explored and characterized for operation at the radial resonance frequencies; however, high-resolution ultrasound imaging requires broadband signals. We explore the characteristics of the broadband beam profile of ACCObeam. This requires beam profile characterization at multiple frequencies, typically incurring long measurement times. We investigate the possibility of characterizing beam profiles at multiple frequencies by exciting the ACCObeam with a broadband waveform such as a linear chirp or a Gaussian pulse. Subsequent post-processing can extract the beam profile for any specific frequency. In this talk, we present ACCObeam broadband measurements and compare them with both fixed-frequency measurements as well as numerical simulation. We also discuss the important parameters that affect the quality of beam profile characterization.