30 September 1994 Sheared-beam imaging in the presence of space-time distortions
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Abstract
In sheared beam imaging, a target is coherently illuminated with three sheared and modulated beams. Both target motion and the temporal distribution of the laser illumination affect image recovery. Movement of the target will cause a corresponding motion of the target's speckle pattern on the ground. As the speckle pattern travels across the detector, each integration period, or bin, in a single laser pulse, or frame, will record a slightly different speckle distribution. This phenomenon effects a smearing of the speckle formation from bin to bin within a single frame, and subsequently degrades the recovered image. Image recovery is further complicated by temporally nonuniform illumination. Both smearing and nonuniform pulse shapes create distortions in the spatial and temporal distributions of the speckle patterns that garble image recovery. This paper documents the derivation of the governing equations for the simulation of sheared beam imaging in the presence of these space-time distortions. In addition, we present algorithms for alleviating these distortions prior to image reconstruction. We conclude with simulation results showing the effect of the space-time distortions on sheared beam image recovery and the improvement achieved with the post-detection deblurring and pulse correction algorithms.
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Barbara Tehan Landesman, Barbara Tehan Landesman, David F. Olson, David F. Olson, } "Sheared-beam imaging in the presence of space-time distortions", Proc. SPIE 2302, Image Reconstruction and Restoration, (30 September 1994); doi: 10.1117/12.188045; https://doi.org/10.1117/12.188045
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