Remote Sensing of Refractive Turbulence with Optical Spatial Filters

Abstract

If a point source of light is allowed to propagate some distance through atmospheric turbulence, it will generate a random pattern of irradiance containing a wide range of spatial scales. Similarly, if an extended light source is viewed through atmospheric turbulence by a point detector, the irradiance at the detector will vary as if the extended source was a random pattern containing a wide range of spatial scales. These phenomena can be analyzed by assuming that light scattered by each scale size of refractive fluctuations in the atmosphere at each position along the propagation path reaches the observation plane with no perturbations from refractive fluctuations at other scale sizes or path positions. This analysis will be valid as long as the path-integrated turbulence is low and saturation of scintillation can be neglected.