26 July 1993 Iterative image reconstruction from the bispectrum of astronomical speckle interferograms
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Proceedings Volume 1983, 16th Congress of the International Commission for Optics: Optics as a Key to High Technology; 198328 (1993) https://doi.org/10.1117/12.2308499
Event: 16th Congress of the International Commission for Optics: Optics as a Key to High Technology, 1993, Budapest, Hungary
Abstract
The atmosphere of the earth restricts the angular resolution of large, ground-based telescopes to about 0.5 arc- sec. Atmospheric image degradation can be overcome by various interferometric speckle techniques. Bispectrum analysis 1,2 (also called speckle masking) of many speckle interferograms (short-exposure photographs; exposure time 0.05 sec) yields diffraction-limited images with, for example, 0.02 arcsec resolution for a 5 m telescope. After the first processing steps of speckle masking the object bispectrum 0(3)(u, v) is obtained up to the cut-off frequency of the telescope. From the object bispectrum a diffraction-limited image can be derived by (a) the conventional recursive method 2 (the object Fourier phase is extracted recursively from 0(3)(u, v)) or (b) iterative least-squares methods. The iterative building block method3-7 discussed below is an extension of the gridfit method8 used in radio interferometry. This algorithm searches for that high-resolution image which has the best agreement with the measured object bispectrum.
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K.-H. Hofmann, K.-H. Hofmann, } "Iterative image reconstruction from the bispectrum of astronomical speckle interferograms", Proc. SPIE 1983, 16th Congress of the International Commission for Optics: Optics as a Key to High Technology, 198328 (26 July 1993); doi: 10.1117/12.2308499; https://doi.org/10.1117/12.2308499
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