Detailed analysis of the first MOAO results obtained by CANARY at the WHT

F. Vidal, E. Gendron, G. Rousset, T. Morris, M. Brangier, A. Basden, Z. Hubert, R. Myers, F. Chemla, A. Longmore, T. Butterlay, N. Dipper, C. Dunlop, D. Geng, D. Gratadour, D. Henry, P. Laporte, N. Looker, D. Perret, A. Sevin, G. Talbot, and E. Younger, “Detailed analysis of the first MOAO results obtained by CANARY at the WHT,” in Second international Conference on Adaptive Optics for Extremely Large Telescopes, Victoria, Canada, Sep. 2011.

Abstract: CANARY is the multi-object adaptive optics (MOAO) pathfinder for the multi object IR spectrometer EAGLE currently proposed on the European Extremely Large Telescope (E-ELT). CANARY was installed in September 2010 on the William Herschel Telescope (WHT) Canary Islands, Spain. For the first time, MOAO correction has been demonstrated using 3 widely separated off-axis natural guide stars and one deformable mirror in open loop in a target direction. A fourth on-axis wavefront sensor (WFS), called truth sensor (TS) was used to characterise the residual error of the MOAO correction. As the TS is placed after the deformable mirror it also permits CANARY to operate as a classical on-axis closed-loop AO system for performance comparison purposes.
We present the detailed analysis of the fourth night of the September observation run (2010 Sep. 27th). Strehls ratios of 0.20 in H band were measured in MOAO mode while achieving 0.25 in close loop configuration (r0 = 15 cm at 0.5 microns). We also acquired synchronised slopes from the 3 off-axis WFS and the TS and from these data we derive the full error budget of CANARY. We pay particular attention to the performance of the tomographic reconstruction and the open loop error. We also discuss the turbulence profile retrieved during the night that was directly measured from the instrument data in order to compute an optimized tomographic reconstruction of the on-axis wavefront.