Monte Carlo ray-tracing simulation of light scattering in particulate media with optically contrast structure

A computer ray-tracing model of light scattering is implemented to calculate phase curves of particulate media consisting of spheres with isotropic indicatrix. In the geometric optics approximation the model takes into account shadowing and multiple scattering up to the tenth order. We study two classes of optically inhomogeneous media: (1) homogeneous-on-average media composed by dark and bright particles of different sizes and (2) media composed by dark and white particles that separately form large domains. Media with such an optically contrast structure demonstrate very different optical properties in comparison with equivalent optically homogeneous particulate surfaces. For example, media with the bright/dark domain structure become brighter when the domain size grows. This is related to that multiple scattering is effectively developed inside the domains with white particles, whereas in optically contrast well-mixed media multiple scattering is well suppressed. Brightening of media with the domain growth becomes more prominent for densely packed media. (C) 2004 Elsevier Ltd. All rights reserved.