Collimated Acoustic Beams from Radial Modes of Piezoelectric Disc Transducers

A novel approach to acoustic collimated beam generation is discussed. It relies on the radial modes of vibration of piezoelectric discs. Ultrasonic beam generation from these radial modes is investigated using numerical simulations and experiments. A free piezo-disc generates Bessel beams that possess a well-collimated central lobe and significant side-lobes. Clamping the lateral edge of the disc was shown to drastically reduce the side-lobes, generating a highly collimated acoustic beam. This technique has a wide variety of low-frequency ultrasonic applications as in borehole integrity monitoring, particle manipulation and acousto-optics.