Synthesis of a specific wavefront using 2D full and sparse arrays

A new application of the time-reversal approach is proposed, i.e., the synthesis of a specific wavefront (plane and short wavefront) in the near-field domain of a transducer array. The theoretical background for computing the temporal excitation signals that must be emitted on the different channels of the array is presented. The efficiency of this approach is illustrated with two kinds of transducer arrays: a full and periodic array containing 1024 elements and a sparse array made of 128 elements. These results are obtained through numerical software; they prove that it is theoretically possible to create any desired wavefront shape if the array contains enough independent elements. Experimental results obtained with a real sparse array are presented