Rainbow-enhanced forward glory from fused-silica spheres
A tertiary rainbow enchances the forward glory scattering from a fused-silica sphere because of its refractive index m ≈ 1.465. The scattered light contains a strong cross-polarized component and varies rapidly in brightness with changes in m. In experiments m is varied by the use of a range of argon and dye laser wavelengths. The forward cross-polarized scattering is found to be in agreement with Mie theory calculations. A reflective coating on small areas around the equator and polar caps of the sphere increases the forward scattering by a factor of ∼180.
D'Amico JJ, Knudson MD, Langley DS. 1994. Rainbow-enhanced forward glory from fused-silica spheres. Applied Optics 33(21): 4672-4676. https://doi.org/10.1364/AO.33.004672