Inverse ray tracing in elastic solids with unknown anisotropy

The problem of inverse ray tracing in a homogeneous anisotropic elastic solid is considered. The wave speeds in the solid are assumed unknown, and must be obtained in the course of the inversion. The specific problem of locating a crack tip in a two-dimensional geometry is investigated. The data are assumed to be in the form of travel times of diffracted ultrasonic signals between transducers positioned on an exterior surface of the solid. Both pulse-echo and pitchcatch data are considered. It is found that travel-time data on the exterior surface suffices to locate