2015
Authors
Guesalaga A.; Neichel B.; Fusco T.; Oberti S.; Valenzuela J.; Masciadri E.; Correia C.; Sauvage J.F.;
Publication
Adaptive Optics for Extremely Large Telescopes 4 - Conference Proceedings
Abstract
We analyze the altitude distribution of the turbulence outer scale - L0(h) - at Cerro Pachón from Gemini South MCAO (GeMS) loop data. GeMS turbulence profiler is fed with telemetry from their 5 WFSs and from the voltages applied to the deformable mirrors, providing estimations of r0, Cn2(h), wind profile (speed and direction for every layer), isoplanatic angle and the outer scale distribution L0(h). It is shown that this last parameter ranges from less than 1 meter at the ground to more than 50m (the telescope is insensitive to larger cannot detect differences above this value). The technique is based on cross correlations of the pseudo-open-loop slopes that allow to disentangle the multiple constituents of L0.
2015
Authors
Morris T.; Basden A.; Buey T.; Chemla F.; Conan J.M.; Correia C.; Dohlen K.; Fusco T.; Gendron E.; Gratadour D.; Jagourel P.; Myers R.; Neichel B.; Petit C.; Rees P.; Rousset G.;
Publication
Adaptive Optics for Extremely Large Telescopes 4 - Conference Proceedings
Abstract
MOSAIC is the proposed multiple object spectrograph for the E-ELT that will eventually combine two AO observing modes within a single instrument. MOSAIC will contain up to 20 open-loop multiple object AO channels feeding NIR IFUs in addition to up to 200 seeing-limited (or GLAO corrected) VIS - NIR fibre pickoffs. Wavefront tomography will be implemented using a combination of LGS and a few high-order NGS distributed across the field with the wavefront correction applied in a split open/closed loop configuration. MOSAIC will be the only E-ELT instrument planned that can utilize the full 10 arcminute diameter field of view, enabling highly efficient observing modes for this workhorse instrument. Use of the full E-ELT field inevitably requires a closer integration between the telescope control system and the instrument AO systems, however this can bring several potential benefits to overall system performance. Here we present the initial design concept and baseline performance of the MOSAIC instrument and AO system(s) taking advantage of the CANARY on-sky results and inheriting from the previous Phase A study of EAGLE. Finally, we will highlight areas of system performance and calibration that will require further analysis and trade-off during the course of the upcoming Phase A study.
2015
Authors
Lamb, M; Andersen, DR; Véran, JP; Correia, C; Lardière, O;
Publication
Adaptive Optics for Extremely Large Telescopes 4 - Conference Proceedings
Abstract
Contemporary AO systems, such as the Multi-Object Adaptive Optics system (MOAO) RAVEN currently associated with the Subaru Telescope, can suffer from significant Non-Common Path Aberrations (NCPA). These errors ultimately affect image quality and arise from optical path differences between the wavefront sensor (WFS) path and the science path. A typical correction of NCPA involves estimating the aberration phase and correcting the system with an offset on the deformable mirror (DM). We summarize two methods used to correct for NCPA on an experimental bench. We also successfully calibrate the NCPA on RAVEN using one of these methods. Finally, we report on some first science results with RAVEN, obtained after NCPA correction.
2015
Authors
Lardière, O; Ono, Y; Andersen, D; Bradley, C; Blain, C; Davidge, T; Gamroth, D; Gerard, B; Jackson, K; Lamb, M; Nash, R; Rosensteiner, M; Venn, K; Van Kooten, M; Véran, JP; Correia, C; Oya, S; Hayano, Y; Terada, H; Akiyama, M; Suzuki, G; Schramm, M;
Publication
Adaptive Optics for Extremely Large Telescopes 4 - Conference Proceedings
Abstract
Raven is a Multi-Object Adaptive Optics science demonstrator which has been used on-sky at Subaru telescope from May 2014 to July 2015. Raven has been developed at the University of Victoria AO Lab, in partnership with NRC, NAOJ and Tohoku University. Raven includes three open loop WFSs, a central laser guide star WFS, and two science pick-off arms feeding light to the Subaru IRCS spectrograph. Raven supports different AO modes: SCAO, open-loop GLAO and MOAO. This paper gives an overview of the instrument design, compares the on-sky performance of the different AO modes and presents some of the science results achieved with MOAO.
2015
Authors
Correia, CM; Jackson, K; Véran, JP; Andersen, D; Lardière, O; Bradley, C;
Publication
Applied Optics
Abstract
Multi-object astronomical adaptive optics (MOAO) is now a mature wide-field observation mode to enlarge the adaptive-optics-corrected field in a few specific locations over tens of arcminutes. The work-scope provided by open-loop tomography and pupil conjugation is amenable to a spatio-angular linear-quadratic-Gaussian (SA-LQG) formulation aiming to provide enhanced correction across the field with improved performance over static reconstruction methods and less stringent computational complexity scaling laws. Starting from our previous work [J. Opt. Soc. Am. A 31, 101 (2014)], we use stochastic time-progression models coupled to approximate sparse measurement operators to outline a suitable SA-LQG formulation capable of delivering near optimal correction. Under the spatio-angular framework the wavefronts are never explicitly estimated in the volume, providing considerable computational savings on 10-m-class telescopes and beyond. We find that for Raven, a 10-m-class MOAO system with two science channels, the SA-LQG improves the limiting magnitude by two stellar magnitudes when both the Strehl ratio and the ensquared energy are used as figures of merit. The sky coverage is therefore improved by a factor of ~5. © 2015 Optical Society of America.
2015
Authors
Correia, CM; Jackson, K; Veran, JP; Andersen, D; Lardiere, O; Bradley, C;
Publication
APPLIED OPTICS
Abstract
Multi-object astronomical adaptive optics (MOAO) is now a mature wide-field observation mode to enlarge the adaptive-optics-corrected field in a few specific locations over tens of arcminutes. The work-scope provided by open-loop tomography and pupil conjugation is amenable to a spatio-angular linear-quadratic-Gaussian (SA-LQG) formulation aiming to provide enhanced correction across the field with improved performance over static reconstruction methods and less stringent computational complexity scaling laws. Starting from our previous work [J. Opt. Soc. Am. A 31, 101 (2014)], we use stochastic time-progression models coupled to approximate sparse measurement operators to outline a suitable SA-LQG formulation capable of delivering near optimal correction. Under the spatio-angular framework the wavefronts are never explicitly estimated in the volume, providing considerable computational savings on 10-m-class telescopes and beyond. We find that for Raven, a 10-m-class MOAO system with two science channels, the SA-LQG improves the limiting magnitude by two stellar magnitudes when both the Strehl ratio and the ensquared energy are used as figures of merit. The sky coverage is therefore improved by a factor of similar to 5. (C) 2015 Optical Society of America
The access to the final selection minute is only available to applicants.
Please check the confirmation e-mail of your application to obtain the access code.