Ray Paths in Inhomogeneous Anisotropic Media

Abstract

The paths of rays in inhomogeneous anisotropic media are studied, starting from Fermat's Principle of Stationary Time. The media considered have a refractive index which depends on the angle between the direction of propagation and an axis of symmetry in the medium, and on several scalar parameters; both these and the direction of the axis are functions of position. Expressions are developed for the curvature of a ray path and are applied to (a) radio rays in an ionized medium pervaded by a non-uniform magnetic field and (b) acoustical rays in a moving fluid.