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Proceedings Paper

Symmetrically weighted center of gravity for Shack-Hartmann wavefront sensing on a laser guide star
Author(s): Damien Gratadour; Eric Gendron; Gerard Rousset
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Paper Abstract

Phase local gradient measurements in a Shack-Hartmann (SH) wavefront sensor (WFS) are achieved by tracking the displacements of a spot in each sub-aperture. This can be done by comparing the position of its center-ofgravity (COG) to a reference position. A commonly used method for position tracking is the weighted (W) COG in which the original image is multiplied by a weighting function, before centroiding. However, it can be shown that, if the spot centered on its COG is not even, the WCOG estimator is biased. We propose a new method for spot centroiding with a direct application to wavefront sensing on a LGS: the symmetrically weighted (SW) COG, in which the weighting function is taken as the symmetrical version of the spot, with respect to its COG.

Paper Details

Date Published: 29 July 2010
PDF: 8 pages
Proc. SPIE 7736, Adaptive Optics Systems II, 773656 (29 July 2010); doi: 10.1117/12.856706
Show Author Affiliations
Damien Gratadour, LESIA, CNRS, Observatoire de Paris à Meudon, Univ. Paris-Diderot (France)
Eric Gendron, LESIA, CNRS, Observatoire de Paris à Meudon, Univ. Paris-Diderot (France)
Gerard Rousset, LESIA, CNRS, Observatoire de Paris à Meudon, Univ. Paris-Diderot (France)


Published in SPIE Proceedings Vol. 7736:
Adaptive Optics Systems II
Brent L. Ellerbroek; Michael Hart; Norbert Hubin; Peter L. Wizinowich, Editor(s)

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