Friday, October 31, 1986 12:00 p.m.
Terry L. Foreman
Applied Research Laboratories
The University of Texas at Austin
Geometrical ray theory has proven to be a versatile and popular method for obtaining approximate solutions to the Helmholtz equation
in such diverse fields as optics and underwater acoustics. But ray theory suffers from several deficiencies, perhaps the most serious of which are the neglect of diffraction and the prediction of singularities at caustics. A modified ray theory is proposed in which the approximation giving rise to the deficiencies is avoided, with the result that the ray path trajectories become frequency dependent. Preliminary investigations based on numerical calculations of frequency dependent ray path trajectories have revealed ray paths which lack the multipathing characteristic of classical ray theory and otherwise differ strikingly from their classical counterparts, raising questions about the nature of the classical ray theory approximation.