Modelling of laboratory data of bi-directional reflectance of regolith surface containing Alumina

TL;DR

This study presents laboratory measurements of bidirectional reflectance of alumina particles at different wavelengths and sizes, analyzing the data using radiative transfer models and phase functions to improve understanding of surface scattering properties.

Contribution

The paper provides new laboratory data on alumina's bidirectional reflectance and applies radiative transfer models with different phase functions to interpret the data.

Findings

Reflectance varies with particle size and wavelength.

Mie theory effectively models scattering for alumina particles.

Hapke model combined with phase functions fits laboratory data.

Abstract

Bidirectional reflectance of a surface is defined as the ratio of the scattered radiation at the detector to the incident irradiance as a function of geometry. The accurate knowledge of the bidirectional reflection function (BRF) of layers composed of discrete, randomly positioned scattering particles is very essential for many remote sensing, engineering, biophysical applications and in different areas of Astrophysics. The computations of BRF's for plane parallel particulate layers are usually reduced to solve the radiative transfer equation (RTE) by the existing techniques. In this work we present our laboratory data on bidirectional reflectance versus phase angle for two sample sizes of 0.3 and 1 $\mu m$ of Alumina for the He-Ne laser at 632.8 nm (red) and 543.5nm(green) wavelength. The nature of the phase curves of the asteroids depends on the parameters like- particle size, composition, porosity, roughness etc. In our present work we analyse the data which are being generated using single scattering phase function i.e. Mie theory considering particles to be compact sphere. The well known Hapke formula will be considered along with different particle phase function such as Mie and Henyey Greenstein etc to model the laboratory data obtained at the asteroid laboratory of Assam University.