Advanced image processing and wavefront sensing with real-time phase diversity

Abstract

This paper will describe a state-of-the-art approach to real-time wavefront sensing and image enhancement. It will explore Boeing's existing technology to realize a 50 Hz frame rate (with a path to 1 KHz and higher). At this higher rate, phase diversity will be readily applicable to compensate for distortions of large dynamic bandwidth such as those of the atmosphere. We will describe various challenges in aligning a two-camera phase diversity system. Such configurations make it almost impossible to process the captured images without additional upgrade in the algorithm to account for alignment errors. An example of an error is the relative misalignment of the two images, the "best-focus" and the diversity image, where it is extremely hard to maintain alignment to less than a fraction of 1 pixel. We will show that the algorithm performance increases dramatically when we account for these errors in the estimation process. Preliminary evaluation has assessed a National Imagery Interpretability Rating Scale increase of approximately 3 from the best-focus to the enhanced image. Such a performance improvement would greatly increase the operating range (or, equivalently, decrease the weight) of many optical systems.