Non-destructive identification of spherical inclusions

Small coated particles and especially small coated spheres, are fundamental units in a particular class of composite materials. The physical characteristics of the core of a particle can be identified through low frequency inverse scattering techniques, in a completely non-destructive manner. Using point source, as well as, plane wave excitation, it can be identified whether the core is consisted of an acoustically soft, hard, or resistive kernel, or if it is a penetrable body having different physical characteristics from that of the coating material. Furthermore, the thickness of the shell can be evaluated assuming the physical parameters (two different densities of the two spheres) are known. Otherwise, if the thickness of the shell is known, the density ratio of the two media can be obtained from one single measurement. Consequently, the density of the core can be found when the density of the shell is known and vice versa.