ANGULAR-DISTRIBUTION OF DIFFUSELY TRANSMITTED LIGHT

The angular dependence of light diffusely transmitted through an opaqu e medium is shown to depend directly on the reflective nature of the s ample boundary, independent of scattering anisotropy. Experimental dat a are presented for glass frits and for liquid samples, such as colloi dal suspensions and aqueous foams, contained in glass cells and placed in either air, water, or glycerin baths. Results compare well with a simple theoretical prediction based on the diffusion approximation and also with random walk simulations. The importance of this work is not only in providing a simple quantitative explanation of a complex tran sport problem, but in establishing the proper treatment of boundary co nditions for diffusion theory analyses of multiple light scattering ex periments.