MAD On-Sky Results in Star Oriented Mode

Laser-guide-star multiconjugate adaptive optics (MCAO) systems require natural guide stars (NGS) to measure tilt and tilt-anisoplanatism modes. Making optimal use of the limited number of photons coming from such, generally dim, sources is mandatory to obtain reasonable sky coverage, i.e., the probability of finding asterisms amenable to NGS wavefront (WF) sensing for a predefined WF error budget. This paper presents a Strehl-optimal (minimum residual variance) spatiotemporal reconstructor merging principles of modal atmospheric tomography and optimal stochastic control theory. Simulations of NFIRAOS, the first light MCAO system for the thirty-meter telescope, using ∼500 typical NGS asterisms, show that the minimum-variance (MV) controller delivers outstanding results, in particular for cases with relatively dim stars (down to magnitude 22 in the H-band), for which lowtemporal frame rates (as low as 16 Hz) are required to integrate enough flux. Over all the cases tested ∼21 nm rms median improvement in WF error can be achieved with the MV compared to the current baseline, a type-II controller based on a double integrator. This means that for a given level of tolerable residual WF error, the sky coverage is increased by roughly 10%, a quite significant figure. The improvement goes up to more than 20% when compared with a traditional single-integrator controller.

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“…Only one NGS MCAO system has been developed, with the main purpose of demonstrating the MCAO concept, but it is limited to few science cases [6].…”

Section: Tilt-anisoplanatism In Laser-tomography Adaptive-optics Systemsmentioning

confidence: 99%

Increased sky coverage with optimal correction of tilt and tilt-anisoplanatism modes in laser-guide-star multiconjugate adaptive optics

et al. 2013

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“…The concept is far more reaching than only a deformable secondary mirror (DSM) since the instrument park (HAWK-I, MUSE, and later ERIS) is optimized to benefit from this upgrade. Several novel adaptive correction modes are also envisioned making use of a sophisticated Laser launch facility that will provide 4 LGS for wavefront sensing (for more details, see Arsenault et al 2014, these proceedings).…”

Section: Discussionmentioning

confidence: 99%

“…Closed loop behavior (including loop lag) and realistic gains are also sent to PAOLA's engine. The model and its detailed parameters have been fine tuned against real data in various conditions, using RTC estimates and Strehl measurement tools such as the MAD Strehl Meter, 4 and ABISM (Girard et al 2014, these proceedings). The relative accuracy of the prediction has been measure to be of the order of ±5% in various seeing conditions.…”

Section: Nacomentioning

confidence: 99%

Real-time Strehl and image quality performance estimator at Paranal Observatory

Mawet¹,

Smette²,

Sarazin³

et al. 2014

SPIE Proceedings

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Here we describe a prototype Strehl and image quality performance estimator and its integration into Paranal operations, starting with UT4 and its suite of three infrared instruments: adaptive optics-fed imager/spectrograph NACO (temporarily out of operations) and integral field unit SINFONI, as well as wide-field imager HAWK-I. The real-time estimator processes the ambient conditions (seeing, coherence time, airmass, etc.) from the DIMM, and telescope Shack-Hartmann image analyzer to produce estimates of image quality and Strehl ratio every ∼ 30 seconds. The estimate is using ad-hoc instrumental models, based in part on the PAOLA adaptive optics simulator. We discuss the current performance of the estimator vs real IQ and Strehl measurements, its impact on service mode efficiency, prospects for full deployment at other UTs, its use for the adaptive optics facility (AOF), and inclusion of the SLODAR-measured fine turbulence characteristics.

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“…GLAO with natural guide stars has been demonstrated to work well with ESO's MAD instrument [10]. GLAO systems using a single Rayleigh guide star are in operation or development at the SOAR [13] and at the WHT [12].…”

Section: Ground Layer Adaptive Opticsmentioning

confidence: 99%

ARGOS: the laser guide star system for the LBT

et al. 2010

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ARGOS is the Laser Guide Star adaptive optics system for the Large Binocular Telescope. Aiming for a wide field adaptive optics correction, ARGOS will equip both sides of LBT with a multi laser beacon system and corresponding wavefront sensors, driving LBT's adaptive secondary mirrors. Utilizing high power pulsed green lasers the artificial beacons are generated via Rayleigh scattering in earth's atmosphere. ARGOS will project a set of three guide stars above each of LBT's mirrors in a wide constellation. The returning scattered light, sensitive particular to the turbulence close to ground, is detected in a gated wavefront sensor system. Measuring and correcting the ground layers of the optical distortions enables ARGOS to achieve a correction over a very wide field of view. Taking advantage of this wide field correction, the science that can be done with the multi object spectrographs LUCIFER will be boosted by higher spatial resolution and strongly enhanced flux for spectroscopy. Apart from the wide field correction ARGOS delivers in its ground layer mode, we foresee a diffraction limited operation with a hybrid Sodium laser Rayleigh beacon combination.

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MAD On-Sky Results in Star Oriented Mode

Cited by 12 publications

References 5 publications

Increased sky coverage with optimal correction of tilt and tilt-anisoplanatism modes in laser-guide-star multiconjugate adaptive optics

Increased sky coverage with optimal correction of tilt and tilt-anisoplanatism modes in laser-guide-star multiconjugate adaptive optics

Real-time Strehl and image quality performance estimator at Paranal Observatory

ARGOS: the laser guide star system for the LBT

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