A Method for Simultaneous Creation of an Acoustic Trap and a Quiet Zone

Paper in proceeding, 2018

An acoustical levitation trap can be created by max- imizing the Laplacian of the Gor’kov potential and minimizing the pressure at a given location. Marzo et al. have successfully used Broyden-Fletcher-Goldfarb-Shanno minimization to find the phases to be imposed on the elements of an ultrasonic transducer array to create the required pressure field. We extend this method to create a field with one acoustical trap and a quiet zone at a different location. This can be used to, for example, create an independent second trap at the location of the quiet zone. We show through numerical simulations that it is possible to create such sound fields using ultrasonic arrays, and we demonstrate the advantages of the proposed approach over the direct design of a sound field with more than one trap. Our method can create a quiet zone extending almost two wavelengths without affecting the levitation trap.