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Evaluation of image shift measurement algorithms for solar Shack-Hartmann wavefront sensors
Stockholm University, Faculty of Science, Department of Astronomy. (Institute for Solar Physics)
2010 (English)In: Astronomy and Astrophysics, ISSN 0004-6361, E-ISSN 1432-0746, Vol. 524, A90- p.Article in journal (Refereed) Published
Abstract [en]

Context. Solar Shack-Hartmann wavefront sensors measure differential wavefront tilts as the relative shift between images from different subapertures. There are several methods in use for measuring these shifts. Aims: We evaluate the inherent accuracy of the methods and the effects of various sources of error, such as noise, bias mismatch, and blurring. We investigate whether Z-tilts or G-tilts are measured. Methods: We test the algorithms on two kinds of artificial data sets, one corresponding to images with known shifts and one corresponding to seeing with different r0. Results: Our results show that the best methods for shift measurements are based on the square difference function and the absolute difference function squared, with subpixel accuracy accomplished by use of two-dimensional quadratic interpolation. These methods measure Z-tilts rather than G-tilts.

Place, publisher, year, edition, pages
2010. Vol. 524, A90- p.
URN: urn:nbn:se:su:diva-52901DOI: 10.1051/0004-6361/201015331OAI: diva2:389295
Available from: 2011-01-19 Created: 2011-01-19 Last updated: 2011-02-15Bibliographically approved

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Löfdahl, Mats
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