Estimating the noise power of the backscattering of light by automobile headlights in fog

Based on the small-angle diffusion approximation of radiation-transfer theory, the noise power is calculated for backscattering from the fog lamps of an automobile and of the high-beam and low-beam headlights under conditions of multiple scattering, taking into account the angular dependence of the scattering distribution close to the backward direction. Cases of different relative positions of the driver and the lamp are considered. Examples are used to illustrate the effect of the mounting parameters of the headlight and its light distribution on optical noise in an active visual system. (C) 1997 The Optical Society of America.