Practical sub-λ/2 acoustic focusing using a liquid-immersed metamaterial lens

Abstract

The sub-λ/2 focusing, also known as super resolution, is widely studied in optics, but only few practical realizations are done in acoustics. In this contribution, I show a novel way to produce sub- λ/2 focusing in the acoustic realm. I used an oil-filled cylinder immersed in liquid to focus an incident plane wave into a line focus. Three different immersion liquids were tested: water, olive oil, and pure ethanol. In addition to the practical experiment, we conducted a series of finite element simulations, by courtesy of Joni Mäkinen, to compare to the experimental results.