Centroid gain compensation in a Shack-Hartmann adaptive optics system; implementation issues

摘要

In an adpative optics system with an undersampled Shack-Hartmann wavefront sensor (WFS), variations in seeing, laser guide star quality, and sodium layer thickness and range distance all combine to vary WFS centroid gain across the pupil during an exposure. While using the minimum of four pixels per WFS sub-aperture improves frame rate and read noise, the WFS centroid gain uncertainty may introduce static aberrations and degrade servo-loop phase margin. In a recent paper~1, we have presented a novel method to estimate and compensate WFS gains of each sub-=aperture individually in real itme for both natural and laser guide stars. In this paper, we address additiona lissues related to the implementation of this method in a real system such as Altair for Gemini North.