Far-field superresolution imaging using shaped acoustic vortices

Abstract

The ability to overcome the limitations on resolution due to the effects of diffraction has attracted significant attention in recent years. Previously proposed methods to overcome this limit, and therefore achieve superresolution, have largely been restricted to operating within the near-field region of the aperture. In this work, we will describe how acoustic helicoidal waves can create acoustic vortices that are well below the resolution limit, and how this can enable far-field superresolution acoustic imaging. The acoustic vortices generated in this manner propagate from the near-field into the far-field through an arrangement of stable integer mode vortices, thereby enabling the generation of far-field superresolved features in the acoustic pressure field. In this paper, theoretical and numerical results will be presented for an acoustic aperture which is capable of generating superresolved far-field features in the radiated acoustic pressure, and results will be shown illustrating the superresolution capability of this novel technique. [Work supported by the Office of Naval Research.]