Analysis of glory phenomena created by retroreflecting microspheres

Abstract

Light fields from localized light sources create a variety of interesting glory phenomena when reflected by small glass spheres (microbeads). Starting with single glass spheres, the interplay of the underlying optical phenomena, i.e., refraction, reflection, diffraction, and dispersion, have been studied both theoretically and experimentally. In a second step, we considered retroreflecting screens formed by flat arrays of tiny glass spheres when exposed to divergent illumination. The arising glories show a specific ring pattern and appear freely floating around the light source as their blurred real image. The investigated glory structures will have numerous applications in sophisticated lamp and illumination designs, as demonstration tools in optical education or advertising, and artistic installations, in particular when appearing as three-dimensional objects by stereoscopic observation.