Imaging with Dynamic-Ripple Diffraction

Abstract

Most methods of point-by-point scanning of acoustic fields employ relatively slow mechanical methods to measure amplitude and phase in the receptor plane. Optical methods of sound field detection have been discussed in a very general way in Chapter 3, and it was pointed out that point-by-point optical scanning has several advantages over direct optical conversion methods. In particular, since the sound field parameters are ultimately translated into electrical signals, electronic filtering may be employed to reject unwanted background. Furthermore, the choice between conventional imaging and holographic imaging is made by changing from linear detection to phase detection, respectively. The commercial availability of lasers and laser beam scanning devices permit the construction of acoustic imaging systems to be relatively straightforward, and with the appropriate devices and TV compatible circuitry, real time imaging is possible.