Blue-green pulsed propagation through fog

Abstract

Measurements and analysis of a blue-green pulsed propagation through fog have identified three distinct regions for energy transport. Region I small number of attenuation lengths τ in the path (0 < τ < 13): here, the direct unscattered beam dominates with an exponential pathloss decay of 4.34 dB/τ. Region II medium number of scattering lengths (13 < τ < 32): multiple scattering is strongly peaked in the forward direction. This energy exhibits small spatial, angular, and temporal spreading and is the main contributor to the received signal. This component also decays exponentially but at at much slower rate of ~2 dB/τ. Region III very large number of scattering lengths (τ > 32): the direct beam and the forwardscattered beam have decayed to the point where the diffusion type multiple-scattered radiation is the dominant energy received. This component does not decay exponentially but results in large spatial, angular, and temporal spreading. This paper presents quantitative data on Region II.