Improving imaging through turbulence via aperture partitioning

摘要

Speckle imaging techniques make it possible to do high-resolution imaging through the turbulent atmosphere by collecting and processing a large number of short-exposure frames, each of which effectively freezes the atmosphere. In severe seeing conditions, when the characteristic scale of atmospheric fluctuations is much smaller than the diameter of the telescope, the reconstructed image is dominated by "turbulence noise" caused by redundant baselines in the pupil. I describe a generalization of aperture masking interferometry that dramatically improves imaging performance in this regime. The approach is to partition the aperture into annuli, form the bispectra of the focal plane images formed from each annulus, and recombine them into a synthesized bispectrum from which the object may be retrieved. This may be implemented using multiple cameras and special mirrors, or with a single camera and a suitable pupil phase mask. I report results from simulations as well as experimental results using telescopes at the Air Force Research Lab's Maui Space Surveillance Site.