Light propagation in biological materials and natural waters

Methods for modelling the behaviour of light in materials which not only absorb, but also scatter light are reviewed, with special emphasis on the Monte Carlo method and Kubelka-Munk theory as applied to biological samples. Two methods for checking model performance are also described, namely determination of photon transit times and fiberoptic measurement of light inside tissues. The directional distribution of light in natural waters, both near the surface and at great depth is described, as well as a computer program for modelling underwater spectral irradiance. The relation between irradiance and fluence rate is explained, and a method for estimating underwater fluence rate from irradiance measurements briefly described.