On the determination of the refractive index of strongly absorbing particles dispersed in a non-absorbing host medium

Abstract

This paper is devoted to the development of a theoretical base for the retrieval of optical constants of large strongly absorbing particles dispersed in a non-absorbing host medium. Both single and multiple scattering regimes are studied. Particles can have a spherical shape or be non-spherical, but convex and randomly oriented. Analytical formulae relating Fresnel reflectivities for surfaces of particles to the intensity of the diffused reflected light are proposed. They are based on the single and quasi-single approximations of the radiative transfer theory. The geometrical optics approximation is used to find local optical characteristics (for example the phase function and the extinction coefficient) of turbid media under consideration.