Time reversal imaging of complex sources in a three-dimensional environment using a spatial inverse filter

Adam D Kingsley; Andrew Basham; Brian E Anderson

doi:10.1121/10.0020664

Time reversal imaging of complex sources in a three-dimensional environment using a spatial inverse filter

J Acoust Soc Am. 2023 Aug 1;154(2):1018-1027. doi: 10.1121/10.0020664.

Authors

Adam D Kingsley¹, Andrew Basham¹, Brian E Anderson¹

Affiliation

¹ Acoustics Research Group, Department of Physics and Astronomy, Brigham Young University, Provo, Utah 84602, USA.

PMID: 37584468
DOI: 10.1121/10.0020664

Abstract

Time reversal focusing above an array of resonators creates subwavelength-sized features when compared to wavelengths in free space. Previous work has shown the ability to focus acoustic waves near the resonators with and without time reversal with an array placed coplanar with acoustic sources, principally using direct sound emissions. In this work, a two-dimensional array of resonators is studied with a full three-dimensional aperture of waves in a reverberation chamber and including significant reverberation within the time reversed emissions. The full impulse response is recorded, and the spatial inverse filter is used to produce a focus among the resonators. Additionally, images of complex sources are produced by extending the spatial inverse filter to create focal images, such as dipoles and quadrupoles. Although waves at oblique angles would be expected to degrade the focal quality, it is shown that complex focal images can still be achieved with super resolution fidelity when compared to free space wavelengths.