Laboratory light scattering from regolith surface and simulation of data by Hapke model

摘要

The small atmosphereless objects of our solar system, such as asteroids, themoon are covered by layer of dust particles known as regolith, formed bymeteoritic impact. The light scattering studies of such dust layer bylaboratory experiment and numerical simulation are two important tools toinvestigate their physical properties. In the present work, the light scatteredfrom a layer of dust particles, containing 0.3{\mu}m Al2O3 at wavelength 632.8nm is analysed. This work has been performed by using a light scatteringinstrument 'ellipsometer', at the Department of Physics, Assam Universiy,Silchar, India. Through this experiment, we generated in laboratory thephotometric and polarimetric phase curves of light scattered from such a layer.In order to numerically simulate this data, we used Hapke's model combined withMie's single particle scattering properties. The perpendicular and parallelcomponents of single particle albedo and the phase function were derived fromMie theory. By using the Hapke's model combined with Mie theory, the physicalproperties of the dust grain such as grain size, optical constant (n,k) andwavelength can be studied through this scheme. In literature, till today notheoretical model to represent polarisation caused due to scattering from roughsurface is available, which can successfully explain the scattering process. Sothe main objective of this work is to develop a model which can theoreticallyestimate polarisation as caused due to scattering from rough surface and alsoto validate our model with the laboratory data generated in the present work.