Response of surface acoustic wave imaging systems to cylindrical inhomogeneities

The authors present a theory to predict the response of a SAW (surface acoustic wave) imaging system. In particular, they calculate the response to cylindrical cavities as a function of cavity position with respect to the focus point. The calculations indicated a high leak rate material will result in a better resolution in the y-direction. The theory also predicts an enhancement in the received signal level when the cylinder circumference equals the SAW wavelength. The images of cylinders obtained with such systems will indicate the size of the cylinders correctly at 20 dB below peak value as long as the cylinder diameter is larger than about a Rayleigh wavelength. For small cylinders the received peak amplitude can be used to determine the size of the cylinder.