Compensating atmospheric turbulence effects at high zenith angles with adaptive optics using advanced phase reconstructors

Atmospheric turbulence degrades the resolution of images of space objects beyond that predicted by diffraction alone. Adaptive optics telescopes have been widely used for compensating these effects, but as users seek to extend the envelopes of operation of adaptive optics telescopes to more demanding conditions, such as daylight operation and operation at low elevation angles, the level of compensation provided will degrade. We have been investigating the use of advanced wave front reconstructors and post detection image reconstruction to overcome the effects of turbulence on imaging systems in these more demanding scenarios. In this paper we show results comparing the optical performance of the exponential reconstructor, the least squares reconstructor, and the stochastic parallel gradient descent algorithm in a closed loop adaptive optics system using a conventional continuous facesheet deformable mirror and a Hartmann sensor. The performance of these reconstructors has been evaluated under a range of source visual magnitudes, and zenith angles up to 67 degrees. We have also simulated satellite images, and applied speckle imaging, multiframe blind deconvolution algorithms, and deconvolution algorithms that presume the average point spread function is known to compute object estimates. ∗All authors are with the Michigan Technological University Department of Electrical and Computer Engineering, 1400 Townsend Dr., Houghton, MI 49931, USA.