Europhys. Lett, 47 (2), pp. 175-181 (1999)
Dynamic time reversal of randomly backscattered acoustic waves
A. Tourin, A. Derode and M. Fink
Laboratoire Ondes et Acoustique, UMR 7587, Université Paris VII Denis Diderot
Ecole Supérieure de Physique et de Chimie Industrielles de la Ville de Paris
10 Rue Vauquelin, 75005 Paris, France
(received 8 February 1999; accepted in final form 12 May 1999)
PACS. 43.20Fn - Scattering of acoustic waves.
PACS. 43.20El - Reflection, refraction, diffraction of acoustic waves.
We report the first experiments using the reversibility of a transient acoustic wave in a multiple-scattering medium to simulate either a stationary or a dynamic acoustic lens. The method is based on time reversal experiments performed in a backscattering configuration. In the stationary case, we show that we take advantage of multiple scattering to focus better than with a perfect reflecting interface. In the dynamic case, we explain the refocused spot time evolution by a simple model based on the time-dependent ability to recover the angular spectrum thanks to both single- and multiple-scattering paths.
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