Phase-diversity techniques for high-resolution active imaging

High-resolution imaging of space-based objects is, and has been, a topic of significant interest. Considerable effort has been expended to develop techniques for compensating or correcting image degradations caused by unknown aberrations, resulting in many successful approaches. However, current techniques are limited to scenarios where the object of interest is either naturally illuminated or is itself radiating. Active illumination using laser light can overcome this limitation, but the applicable coherence properties introduce additional challenges. To utilize laser illumination, a multi-frame phase-diversity image reconstruction algorithm tailored to the statistics of coherent light is developed. The reconstruction problem is posed in the form of a regularized optimization over the space of object pixel values and atmospheric aberration parameters. The optimization objective function is derived from the statistics of the detected light, and a regularization term including information encoded in the pupil-plane intensity statistics is added to include additional knowledge and better condition the inverse problem. A representative coherent imaging system is simulated and reconstruction results are presented.