Problèmes inverses en diffusion acoustique avec des miroirs à retournement temporel

Time-reversal mirror (T.R.M.) utilizes time-reversal invariance of wave equation. Acoustic T.R.M. are made of large transducer arrays allowing the incident acoustic field to be sampled, time-reversed, and re-emitted. Such a process allows an original way of studying acoustical sources. This paper describes an application of T.R.M. to the characterization of extended scatterer illuminated by broad band pulse. The ability of T.R.M. to time-reverse separetely each scattered waves permits to isolate spatially and temporally the equivalent sources of extended scatterer. We investigate more particularly the problem of a cylindrical scatterer : we show that T.R.M. allows to characterize simply the different sources of backscattered waves and especially the mode conversion of incident wave into circumferential waves. Besides, we show that iterative time reversal process allows to generate any particular circumferential wave