Synchronized time-reversal focusing with application to virtual array formation, beam forming, and remote imaging

Abstract

By sampling and time reversing the field from a distant probe source, a time-reversal mirror (TRM) can produce an intense acoustic focus at the probe source location. Extending this idea to a collection of sources, this work demonstrates that a TRM can generate a virtual array at a downrange location, which can act as a remote platform for time delay beam forming and other coherent wavefront techniques useful for imaging in the vicinity of the virtual array. The technique requires no a priori information about the environment, only the knowledge of the source fields and a means for synchronizing them. In one promising application the TRM is used to coherently image an extended region around a distant passive array. The geometry of the source array is arbitrary. Recent advances in self-adaptive acoustic Green’s function determination may provide opportunities to apply this method without need for a source array. Simulation and experimental results are discussed.