Liquid-liquid core-shell configurable mesoscale spherical acoustic lens with subwavelength focusing

In this work, we present a lens based on a thin hollow ABS spherical container structure, which can be filled up with different compatible liquids. The acoustic jet can be dynamically shaped by either shifting the operating frequency or modifying the geometry of the lens. We show for the first time that a spherical Ethanol ABS core-shell acoustical lens immersed in water with low diameter-to-wavelength ratio equal to 6.67 and refraction index of 1.24 achieves a focusing spot narrower than 0.85 lambda. Experimental measurements validate simulation results and demonstrate the viability of these configurable spherical lenses in underwater acoustic focusing applications. (C) 2019 The Japan Society of Applied Physics