PRIMARY SHADOW RADIATION AND CLASSICAL-MODELS OF BLACK BODIES

The notion of primary shadow radiation is introduced. This is a wave f ield created by the transverse diffusion in the vicinity of the geomet rical optics boundary behind a black screen with a special property. T his special screen is located on the boundary between two neighboring Rieman spaces and consists of two faces. These faces together are not transparent to the wave field; but, each separately is transparent. We call this screen the Riemann black screen. The well known classical m odels of black screens are interpreted as special sets of Riemann scre ens.