Multi-frame satellite image reconstruction using adaptive-optics compensation

Abstract

The resolution achieved in space-object imaging is usually limited by turbulence-induced aberrations, which can severely limit the resolution in the images by an order of magnitude or more. The 1.5-meter telescope at the Air Force Research Laboratory Starfire Optical Range (SOR) relies upon an adaptive-optics system to eliminate in real time much of the phase aberration introduced by atmospheric turbulence. Despite the exceptional performance of this system, the correction is never perfect. There are several sources of residual aberrations that degrade the imagery: imperfect wavefront sensing (particularly in low light-level situations), the time lag between sensing and correction (which allows for evolution of the atmosphere and is a particular problem when slewing to track an earth-orbiting space object), and deformable-mirror fitting errors. A post-detection image-reconstruction capability also insures the continuing availability of fine-resolution images, even during adaptive-optics down time owing to routine maintenance or temporary system failure. Therefore, post-detection reconstruction methods provide an important complement to and backup for pre-detection correction.