Application of phase-diversity to solar images

Mats G. Lofdahl; Goran B. Scharmer

doi:10.1117/12.188043

30 September 1994 Application of phase-diversity to solar images

Mats G. Lofdahl, Goran B. Scharmer

Proceedings Volume 2302, Image Reconstruction and Restoration; (1994) https://doi.org/10.1117/12.188043
Event: SPIE's 1994 International Symposium on Optics, Imaging, and Instrumentation, 1994, San Diego, CA, United States

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.

Citation Download Citation

Mats G. Lofdahl and Goran B. Scharmer "Application of phase-diversity to solar images", Proc. SPIE 2302, Image Reconstruction and Restoration, (30 September 1994); https://doi.org/10.1117/12.188043

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