High fidelity sky coverage analysis via time domain adaptive optics simulations

We describe a high fidelity simulation method for estimating the sky coverage of multiconjugate adaptive optics systems; this method is based upon the split tomography control architecture, and employs an AO simulation postprocessing technique to evaluate system performance with hundreds of randomly generated natural guide star (NGS) asterisms. A novel technique to model the impact of quadratic wavefront aberrations upon the NGS point spread functions is described; this is used to model the variations in system performance with different asterisms, and is crucial for obtaining accurate results with the postprocessing technique. Several design and algorithm improvements help to reduce the residual wavefront error in the tip/tilt and plate scale modes that are controlled using the NGS asterism. These improvements include choosing the right wavefront sensor (WFS) pixel size, optimal pixel weights, and type II control of the plate scale modes

Spatio-angular Minimum-variance Tomographic Controller for Multi-Object Adaptive Optics systems

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 arc-minutes. 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 [1], 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 wave-fronts are never explicitly estimated in the volume,providing considerable computational savings on 10m-class telescopes and beyond. We find that for Raven, a 10m-class MOAO system with two science channels, the SA-LQG improves the limiting magnitude by two stellar magnitudes when both Strehl-ratio and Ensquared-energy are used as figures of merit. The sky-coverage is therefore improved by a factor of 5.Comment: 30 pages, 7 figures, submitted to Applied Optic

Multi-Conjugate Adaptive Optics Simulator for the Thirty Meter Telescope: Design, Implementation, and Results

We present a multi-conjugate adaptive optics (MCAO) system simulator bench, HeNOS (Herzberg NFIRAOS Optical Simulator). HeNOS is developed to validate the performance of the MCAO system for the Thirty Meter Telescope, as well as to demonstrate techniques critical for future AO developments. In this paper, we focus on describing the derivations of parameters that scale the 30-m telescope AO system down to a bench experiment and explain how these parameters are practically implemented on an optical bench. While referring other papers for details of AO technique developments using HeNOS, we introduce the functionality of HeNOS, in particular, three different single-conjugate AO modes that HeNOS currently offers: a laser guide star AO with a Shack-Hartmann wavefront sensor, a natural guide star AO with a pyramid wavefront sensor, and a laser guide star AO with a sodium spot elongation on the Shack-Hartmann corrected by a truth wavefront sensing on a natural guide star. Laser tomography AO and ultimate MCAO are being prepared to be implemented in the near future

Estimation de la réponse impulsionnelle spatiale d'un système d'optique adaptative à partir des données de contrôle de boucle

Nous proposons une nouvelle méthode permettant d'estimer la réponse impulsionnelle spatiale d'un système d'optique adaptative pour l'astronomie. Celle-ci dépend fortement des conditions d'acquisition et sa connaissance est essentielle afin de pouvoir améliorer, à l'aide d'algorithmes de déconvolution, le contraste des images acquises. La méthode proposée est plus précise que les méthodes habituellement mises en oeuvre car elle se base sur des données parfaitement synchrones avec l'acquisition. De plus, elle n'occasionne pas de perte de temps d'observation. Sur le Télescope Canada-France-Hawaii, de très bons résultats ont pu être obtenus, pour des sources de référence de magnitude inférieure ou égale à 13

Stellar photometry with Multi Conjugate Adaptive Optics

We overview the current status of photometric analyses of images collected with Multi Conjugate Adaptive Optics (MCAO) at 8-10m class telescopes that operated, or are operating, on sky. Particular attention will be payed to resolved stellar population studies. Stars in crowded stellar systems, such as globular clusters or in nearby galaxies, are ideal test particles to test AO performance. We will focus the discussion on photometric precision and accuracy reached nowadays. We briefly describe our project on stellar photometry and astrometry of Galactic globular clusters using images taken with GeMS at the Gemini South telescope. We also present the photometry performed with DAOPHOT suite of programs into the crowded regions of these globulars reaching very faint limiting magnitudes Ks ~21.5 mag on moderately large fields of view (~1.5 arcmin squared). We highlight the need for new algorithms to improve the modeling of the complex variation of the Point Spread Function across the field of view. Finally, we outline the role that large samples of stellar standards plays in providing a detailed description of the MCAO performance and in precise and accurate colour{magnitude diagrams.Comment: 17 pages, 12 figures, SPIE 201

GPI 2.0: Upgrades to the IFS including new spectral modes

The Gemini Planet Imager (GPI) is a high-contrast imaging instrument designed to directly image and characterize exoplanets. GPI is currently undergoing several upgrades to improve performance. In this paper, we discuss the upgrades to the GPI IFS. This primarily focuses on the design and performance improvements of new prisms and filters. This includes an improved high-resolution prism which will provide more evenly dispersed spectra across y, J, H and K-bands. Additionally, we discuss the design and implementation of a new low-resolution mode and prism which allow for imaging of all four bands (y, J, H and K-bands) simultaneously at R=10. We explore the possibility of using a multiband filter which would block the light between the four spectral bands. We discuss possible performance improvements from the multiband filter, if implemented. Finally we explore the possibility of making small changes to the optical design to improve the IFS's performance near the edge of the field of view.Comment: 8 pages, 5 figures, Proc. of SPIE Paper No. 11447-41