THE POMRANING-EDDINGTON APPROXIMATION TO DIFFUSION OF LIGHT IN TURBIDMATERIALS

The source-free diffusion problem of light in turbid media with genera lized boundary conditions is considered. The intensity of light is con sidered as a sum of collimated and diffused radiance. In this way the problem is transformed to a source problem with a collimated source (p roblem 1). This problem is solved in terms of the corresponding source -free problem of simple boundary conditions (problem 2). The Pomraning -Eddington method is used to solve problem 2. Two coupled first-order differential equations are obtained involving the energy density and t he radiation net flux. Weight functions are introduced in order to for ce the boundary conditions to be fulfilled. Numerical results are give n and compared with previous calculations. The calculations show that the accuracy depends on the choice of the weight function.