This thesis reports on theoretical work concerning the propagation of light in the presence of a large number of small scatterers. By definition a "scatterer" is an object that influences light propagation somehow. To scatter visible light (wavelength: .500 - 600 nanometer) one often makes use of dielectric particles immersed in a fluid, or paint-air pockets. Dielectric materials scatter light by means of refraction which, in turn, is caused by different speeds of light inside and outside the dielectric. Scattering of light can become very efficient if the particle size is of the order of the wavelength. In practice, the shape of the scatterers is hardly ever spherical but is more potato-like. In our theory we assume them to be spherical. We speak about "multiple scattering" if we deal with more than one scatterer. In this thesis we study multiple scattering in the presence of "disorder". Disorder can be of any kind, but the one relevant for many light experiments is called "topological disorder". The scatterers are in that case randomly (for instance Poisson-) distributed in space. Experimentally one usually averages scattered light over many different realizations of the system. Another kind of disorder occurs if the dielectric constant of the scatterers or their size is randomized.

B. A. van Tiggelen

1992

09/1992

Thesis advisor: A. Lagendijk