17 November 2000 Pre- and post-detection correction of turbulence-induced space-variant blur
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Abstract
Space-variant blur occurs when imaging through volume turbulence over sufficiently large fields of view. Space- variant effects are particularly severe in horizontal-path imaging, slant-path (air-to-ground or ground-to-air) geometries, and ground-based imaging of low-elevation satellites or astronomical objects. In these geometries, the isoplanatic angle can be comparable to or even smaller than the diffraction-limited resolution angle. Clearly, space-invariant methods used in conjunction with mosaicing will fail in this regime. Our approach to this problem has been to generalize the method of Phase-diverse Speckle (PDS) by using a physically motivated distributed phase-screen model to accomplish both pre- and post-detection correction. Previously reported simulation results have demonstrated the reconstruction of near diffraction-limited imagery using imagery which was severely degraded by space-variant blur. In this paper, we present a novel adaptation of the space- variant PDS scheme for use as a beacon-less wavefront sensor in a multi-conjugate AO system when imaging extended scenes. We then present results of simulation experiments demonstrating that this multi-conjugate AO-compensation scheme is very effective in improving the quality and resolution of collected imagery.
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Brian J. Thelen, David A. Carrara, Richard G. Paxman, "Pre- and post-detection correction of turbulence-induced space-variant blur", Proc. SPIE 4125, Propagation and Imaging through the Atmosphere IV, (17 November 2000); doi: 10.1117/12.409294; https://doi.org/10.1117/12.409294
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