Quasi-flat high-index acoustic lens for 3D underwater ultrasound focusing

We report a quasi-flat and sub-wavelength acoustic lens built using a soft matter process for broadband ultrasonic 3D focusing in water. By using a simple emulsion templating method, a soft porous material with a high acoustic index relative to water (& SIM;5) has been molded and shaped into a convergent lens with a very low curvature and a thickness smaller than the working wavelength in water. This kind of acoustic metasurface generates a narrow focused beam, and its focal length can be adjusted. These acoustic lenses may be of great interest for underwater applications, where acoustic focusing and imaging are highly demanded. Published under an exclusive license by AIP Publishing.

Automated summary

We present a quasi-flat and sub-wavelength acoustic lens that can achieve broadband ultrasonic 3D focusing in water. This acoustic lens, made from a soft porous material with a high acoustic index relative to water, generates a narrow focused beam and allows for adjustable focal length. It is of great interest for underwater applications requiring acoustic focusing and imaging.