Time reversal kaleidoscope: A smart transducer for three-dimensional ultrasonic imaging

The design of two dimensional (2D) arrays for three dimensional (3D) ultrasonic imaging is a major challenge in medical and nondestructive applications. Thousands of transducers are typically needed for beam focusing and steering in 3D volumes. Here, we report a promising approach for producing 3D images with a small number of transducers using the combined concepts of time reversal mirrors and chaotic reverberating cavities. Due to multiple reverberations inside the cavity, a "kaleidoscopic" transducer array is created with thousands of virtual transducers equivalent to 2D matrices. Beyond the scope of 3D medical imaging, this work leads to the concept of "smart" transducer. (C) 2004 American Institute of Physics.