The stochastic caustic

Geometrical optics is employed in the investigation of the propagation of a high frequency, initially plane wave through a homogeneous and isotropoic random medium with order O(sigma) index of refraction fluctuations. Caustics occur along every ray in a distance scale of order O(sigma to the 2/3-power), while the ray position deviates O(1) from its deterministic value. The present results parallel those of Kulkarny and White (1982) for two-dimensional random media.