Symmetrically weighted center of gravity for Shack-Hartmann wavefront sensing on a laser guide star

Damien Gratadour; Eric Gendron; Gerard Rousset

doi:10.1117/12.856706

28 July 2010 Symmetrically weighted center of gravity for Shack-Hartmann wavefront sensing on a laser guide star

Damien Gratadour, Eric Gendron, Gerard Rousset

Proceedings Volume 7736, Adaptive Optics Systems II; 773656 (2010) https://doi.org/10.1117/12.856706
Event: SPIE Astronomical Telescopes + Instrumentation, 2010, San Diego, California, United States

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.

Citation Download Citation

Damien Gratadour, Eric Gendron, and Gerard Rousset "Symmetrically weighted center of gravity for Shack-Hartmann wavefront sensing on a laser guide star", Proc. SPIE 7736, Adaptive Optics Systems II, 773656 (28 July 2010); https://doi.org/10.1117/12.856706

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