Abstract

When the refractive index m of a sphere is such that rainbows occur in the forward or backward direction, the glory scattering becomes exceptionally strong. A number of these refractive index values have been determined from the geometry of ray paths. Diffraction theory applied to the scattered wavefront leads to an x^4/3 dependence in the scattered irradiance, where x = (sphere circumference/incident wavelength) is the size parameter; normal glory-scattered irradiance increases proportional to x. Mie theory computations illustrate the presence of rainbow-glories at predicted m values, and the x^4/3 irradiance factor. As in normal glory scattering, the rainbow-glory light contains a strong cross-polarized component. Experiments using single glass spheres immersed in liquids have shown cross-polarized scattering and a sensitive dependence on m in agreement with predictions.

© 1990 Optical Society of America