Sound reception system by an acoustic meta-lens

Abstract

ABSTRACT Applying the directionality of an acoustic meta-lens, a sound reception system for ships is designed. A two-dimensional disk shape acoustic meta-lens or an acoustic Luneburg lens made of 253 acrylic pipes of different radii which control the refractive index is used. The lens has the diameter of 180 cm and the thickness of 20 cm. Eight microphones were installed around the edges of the lens because the lens focuses the input signal into the edge of the other side of the lens. The sound reception ability of the lens was tested on the sea using the horn of a university training ship as an emitter and the lens loaded on a small boat as a receiver. Both are moving at 20 ~ 40 km/h at a distance between 300 ~ 700 m. The lens could focus to recognize the direction of the input sound in the frequency range between 300 and 900 Hz. ABBREVIATIONS IMO: International Maritime Organization ALL: Acoustic Luneburg Lens SRS: Sound Reception System