Super resolution, time reversal focusing using path extending properties of scatterers

•Super resolution may be obtained by slowing down acoustic waves with a network of scatterers placed near the location of the intended focusing.•Previous research showed that resonators and absorbers could be used to achieve super resolution, but here scatterers are used.•Scatterers can be used to e...

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Bibliographic Details
Published in:Applied acoustics 2023-04, Vol.206, p.109308, Article 109308
Main Authors: Golightly, Emily D., Anderson, Brian E., Kingsley, Adam D., Russell, Rylee, Higgins, Rebekah
Format: Article
Language:English
Subjects:
Diffraction limit
Super resolution
Time reversal
Time reversal acoustics
Time reversed acoustics
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Summary:•Super resolution may be obtained by slowing down acoustic waves with a network of scatterers placed near the location of the intended focusing.•Previous research showed that resonators and absorbers could be used to achieve super resolution, but here scatterers are used.•Scatterers can be used to extend the path through which waves travel such that the apparent spatial resolution can be improved upon relative to free space. Time reversal is a process where a sound is recorded at a specific location, temporally reversed, and then played back to focus at the same location as the original recording. This paper will focus on the use of scatterers placed within a wavelength (the assumed near field) of time reversal focusing to achieve super resolution. A one-dimensional pipe system is used with extensions that simulate the increased path length due to diffraction around an object. This longer path length, if unaccounted for, leads to a decrease in the effective wave speed. As the effective wave speed decreases, the spatial extent of the focusing decreases, creating super resolution. Although previous work refers to the scattering property of the medium as key to achieving super resolution, this paper shows that the path extending properties of scatterers only show super resolution when the distance between measurements does not take into account the longer path length traveled around scatterers. Consequently, it supports the understanding that resonances within the medium are more likely to yield super resolution focusing than using passive scattering.
ISSN:0003-682X
1872-910X
DOI:10.1016/j.apacoust.2023.109308