Optical scattering is caused by two mechanisms: surface scattering and volume scattering. With the former mechanism, scattered light comes only from the interaction of light with the surfaces of the optical element. When surface scattering is present, light will scatter from an optical element even when the optical material is completely clear and homogeneous. For example, an astronomical telescope mirror reflects light before it even enters the substrate material, so no volume scattering is possible, but telescope mirrors are still susceptible to surface scattering.

Volume scattering, on the other hand, occurs only in the bulk of the optical material and is completely independent of the surfaces. A good example of bulk scattering is earth’s atmosphere. Even on the clearest day the sky will still be blue because of Rayleigh scattering.

We do not deal very much with volume scattering. We are familiar with Rayleigh and Mie scatter, and models such as Henyey Greenstein (original article). We have also interfaced a bit with the computer graphics community and studied their investigations on “participating media” and BSSRDF, such as Henrik Jensen’s papers. But most of our work with optical scattering deals more with surfaces.

There is a lot more information on optical scattering on this site. Please continue to one of the following pages for more information.