ON LIGHT-PROPAGATION THROUGH GLASS BEAD PACKINGS

We investigated the transmission of monochromatic light through porous media consisting of packings of glass beads (bead diameters d in the range of 0.16-0.4 mm) immersed in water. The light propagation through such strongly scattering random media is characterized by the transpo rt mean free path l (distance over which the direction of propagation is randomized) and the diffusive absorption length L(a). We determine d these parameters by combining measurements of total transmission (in the strong absorption regime) with reference measurements on samples with known l. We obtain l* approximate to 7d at the wavelength of 633 nm and l approximate to 9d at 515 nm; the absorption length L(a) lie s between 5 and 10 mm.