Profiling atmospheric turbulence using dual-camera imagery of non-cooperative targets

Phase-based techniques to measure atmospheric turbulence have potential advantages when used over long ranges since they do not suffer from saturation issues as the irradiance-based techniques. The present work uses time-lapse imagery of a non-cooperative target from two spatially separated cameras to extract turbulence distribution along a path. By measuring the differential motion of pairs of extended features on the target, sensed by a single camera or between cameras, turbulence profiles can be obtained. Tracking the motion of extended features rather than point features allows estimation over a longer range. The approach uses a derived set of path weighting functions for differential tilt variances. The mathematical framework is discussed and the technique is applied to images collected of a multi-story building. Turbulence profiles over different slant paths are extracted from features at multiple levels of the building. This work will ultimately help in a better understanding of how turbulence varies with altitude in the surface layer.