Time-reversed sound beams of finite amplitude

Numerical simulations based on the nonlinear parabolic wave equation are us ed to investigate time reversal of sound beams radiated by unfocused and fo cused sources. Emphasis is placed on nonlinear propagation distortion in th e time-reversed beam, and specifically its effect on field reconstruction. Distortion of this kind, due to amplification during time reversal, has bee n observed in recent experiments [A. P. Brysev et al., Acoust. Phys. 44, 64 1-650 (1998)]. Effects of diffraction introduced by time-reversal mirrors w ith finite apertures are also considered. It is shown that even in the pres ence of shock formation, the ability of time reversal to retarget most of t he energy on the source or focal region of the incident beam is quite robus t. (C) 2001 Acoustical Society of America.