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Proceedings Paper

Application of phase-diversity to solar images
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Paper Abstract

We have implemented a least-squares technique for recovering phase information and alignment parameters from simultaneously obtained focused and defocused solar images. Small subfields are used, in order to deal with anisoplanatism. The method is applied to sequences of 100 8-bit solar granulation images. These data enable a number of consistency tests, all of which demonstrate that the technique works. Alignment parameters derived from averaged images in a sequence are highly consistent and wavefronts derived from different subfields and different sequences recorded close in time are virtually identical. The wavefronts derived from averaged images are also virtually identical to the average of wavefronts derived from individual images. These aberrations vary with time in a way which is consistent with a major contribution from the moving elements of the alt-az tower telescope. Independently derived wavefronts from single images show high correlation between neighboring subfields and smooth variations across large fields-of-view, consistent with the impression that the image quality is more or less uniform across the image. Restored images in a sequence show a high degree of consistency and much more fine structure than the corresponding observed images.

Paper Details

Date Published: 30 September 1994
PDF: 14 pages
Proc. SPIE 2302, Image Reconstruction and Restoration, (30 September 1994); doi: 10.1117/12.188043
Show Author Affiliations
Mats G. Lofdahl, Stockholm Observatory/Royal Swedish Academy of Sciences (Sweden)
Goran B. Scharmer, Stockholm Observatory/Royal Swedish Academy of Sciences (Sweden)


Published in SPIE Proceedings Vol. 2302:
Image Reconstruction and Restoration
Timothy J. Schulz; Donald L. Snyder, Editor(s)

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