Self-focusing Rayleigh wave using a time reversal mirror

Detection of surface and subsurface flaws is achieved using the time reversal process leading to self-focusing Rayleigh waves. The generation of surface waves is accomplished with an array of transducers coupled to the specimen with a Plexiglas wedge. The advantages of this technique are demonstrated with the detection of surface and subsurface holes of subwavelength dimensions. An optical interferometer is used to control the surface acoustic field obtained with such a time reversal process. (C) 1996 American Institute of Physics.