Time-reversal of a wave packet emitted by an internal source: the perfect inverse filter

TL;DR

This paper introduces a generalized perfect inverse filter (PIF) for acoustic wave time-reversal, enabling precise wave packet reconstruction from an internal source, with improved focus over traditional time-reversal mirror techniques.

Contribution

It develops a theoretical framework for an internal-source PIF and demonstrates its superior focusing performance through numerical simulations.

Findings

Internal-source PIF achieves better focus than TRM.

Numerical tests confirm improved wave reconstruction quality.

The method enhances minimally invasive acoustic focusing techniques.

Abstract

The time-reversal mirror (TRM) of acoustic waves is used as a focusing technique that is robust against disorder and chaos. The propagation of an ultrasonic pulse from the focal point is detected and recorded by a surrounding array of transducers that enclose the cavity region. The registered signals are then played-back in the reverse temporal sequence and an imperfect Loschmidt echo is obtained. A similar technique developed in the quantum domain, the perfect inverse filter (PIF), ensures an exact reversion. Applied to the acoustical case, it allows an improvement in the design of a minimally invasive inverse filter. Although that version of PIF accounts for external source condition, now we propose a generalization where the initial excitation is created inside the cavity. We present the theoretical principles for this form of PIF and perform a numerical test in a multichannel system that improves the focalization quality compared to the TRM version.