Ultrasonic back scattering measurements allow one to make quantitative (grain size) and qualitative (homogeneity) characterizations of microstructure. We first review the physical principles underlying back scattering measurements. The application of ultrasonic backscattering of volume waves to different types of materials such as various steels and ceramics is presented. Furthermore it is shown that the scattering of Rayleigh waves enables a structural characterization of the surface region.
