Two-dimensional scattering and digital holography from isolated aerosol particles

Non-spherical aerosols, particularly aggregates and those comprised of rough surfaces, produce complex light scattering patterns that deviate considerably from those of their spherical counterparts. Consequently, discerning particle morphology from the complex scattering pattern, i.e., the inverse problem, is difficult at best. Additional information is required to associate uniquely the interference pattern resulting from scattered light and the particle's morphology (size, shape, etc.). This uniqueness challenge of the inverse problem may be overcome by incorporating digital holographic imaging into the light scattering apparatus. Using a color CCD camera, we demonstrate that two-dimensional light scattering patterns and digital holograms from individual owing aerosol particles may be recorded simultaneously at different wavelengths revealing the complex scattering pattern along with the size, shape, and orientation of the particle at the instant the scattering occurs. Knowing the exact scattering pattern associated with an exact particle morphology will improve the understanding the radiative characteristics of non-spherical atmospheric aerosols, and reduce uncertainties of important physical parameters such as radiative forcing of aerosols.