A layered media model for ray propagation in anisotropic inhomogeneous materials

Abstract

We present a model for numerical discrete ray tracing in anisotropic inhomogeneous elastic materials. This model is an alternative to the full solution of the differential equations governing ray propagation. In the model, inhomogeneous materials are treated as layered, each layer being composed of a homogeneous, anisotropic material. We show how to choose these layers such that the exact ray solutions are obtained, illustrating this with reference to the mirage problem in isotropic materials. From this study we conclude that the layers within an inhomogeneous material should be chosen to be parallel to the local directions of constant ray group velocity magnitude. This direction can therefore depend both on the material being studied and on the ray mode and direction being considered. We discuss the incorporation of this choice into our three-dimensional ray tracing model, RAYTRAIM, and present results from this model.