Quasi-specular reflection from particulate media

- Quasi-specular reflection from particulate media is studied.
- Quasi-specular reflection is present for structured particulate media.
- Planar layer of particles is needed, but not necessarily on the very top.
- Can have practical impacts on simulations and laboratory studies of backscattering.

Specular reflection is known to play an important role in many fields of scattering applications, e.g., in remote sensing, computer graphics, optimization of visual appearance of industrial products. Usually it can be assumed that the object has a solid surface and that the properties of the surface will dictate the behavior of the specular component. In this study I will show that media consisting of wavelength-sized particles can also have a quasi-specular reflection in cases where there are ordered structure in the media. I will also show that the quasi-specular reflection in particulate media is more than just a surface effect, and planar particle arrangement below the very surface can give rise to quasi-specular reflection. This study shows that the quasi-specular reflection may contribute in some cases in the backscattering direction, together with coherent backscattering and shadow-hiding effects.