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