Divergence Factor in Ray Model and its Application to Light Scattering by a Large Nonspherical Dielectric Particle

This letter focuses on the description of the divergence factor of a wave in terms of differential geometry, called Vectorial Complex Ray Model (VCRM), and its application in the scattering of a large nonspherical dielectric particle. The VCRM permits to calculate the amplitude and the phase of electric field rigorously in terms of ray model, but it fails to predict correctly the field near caustics (in rainbow angles). This problem is solved by combining the field calculated with VCRM and the physical optics. This hybrid method is then applied, as example, to the scattering of an infinite cylinder and an ellipsoid. The comparison with the rigorous Debye theory shows that our method can predict very precisely the scattered field in all directions including near the rainbow angles. The hybrid method removes the two approximations in Airy theory, so the results are much better. Because of its flexibility, this method can be applied directly to the scattering of a large nonspherical object of smooth surface.