The Gemini MCAO System GeMS: nearing the end of a lab-story

Neichel, Benoît; Rigaut, François; Bec, Matthieu; Boccas, Maxime; Daruich, Felipe; d’Orgeville, Céline; Fesquet, Vincent; Galvez, Ramon; García-Rissmann, Aurea; Gausachs, Gaston; Lombini, Matteo; Pérez, Gabriel; Trancho, Gelys; Upadhya, V.; Vučina, Tomislav

doi:10.1117/12.856716

Cited by 25 publications

(16 citation statements)

References 19 publications

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“…A detailed description of each sub-system can be found in previous papers. 5,20 In short, a 50W laser is split in 5x10W beacons to produce the 5 laser guide stars (LGS) placed on the sky at the corner and center of a 60 arcsec square. These ve LGS are seen by ve, 16x16 subapertures, Shack-Hartmann wavefront sensors.…”

Section: Gemsmentioning

confidence: 99%

Identification and calibration of the interaction matrix parameters for AO and MCAO systems

et al. 2012

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New tomographic Adaptive Optics (AO) concepts require a good knowledge of the system geometry and characteristics. These parameters are used to feed the tomographic reconstructors. In this paper we present a method to precisely identify the parameters required to construct an accurate synthetic set of models such as inuence functions, mis-registrations, directions of analysis or altitude of the DMs. The method is based on a multiparameter t of the interaction matrix. This identication method nds also its application in high contrast AO systems, such as SPHERE : in that case it is used as a diagnostic tool in order to precisely realign the system. The method has been tested and successfully implemented on HOMER, SPHERE and GeMS. Experimental results for these three systems are presented.

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Section: Gemsmentioning

confidence: 99%

Identification and calibration of the interaction matrix parameters for AO and MCAO systems

et al. 2012

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“…Multi-conjugate AO systems for large telescopes offer the possibility of this performance over much larger fields (e.g. [111][112][113][114]). Optical and radio interferometry have demonstrated still higher astrometric precisions (e.g.…”

Section: Introductionmentioning

confidence: 99%

A new probe of the small-scale primordial power spectrum: Astrometric microlensing by ultracompact minihalos

Erickcek

Law

2012

Phys. Rev. D

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The dark matter enclosed in a density perturbation with a large initial amplitude (δρ/ρ 10 −3 ) collapses shortly after recombination and forms an ultracompact minihalo (UCMH). Their high central densities make UCMHs especially suitable for detection via astrometric microlensing: as the UCMH moves, it changes the apparent position of background stars. A UCMH with a mass larger than a few solar masses can produce a distinctive astrometric microlensing signal that is detectable by the space astrometry mission Gaia. If Gaia does not detect gravitational lensing by any UCMHs, then it establishes an upper limit on their abundance and constrains the amplitude of the primordial power spectrum for k ∼ 2700 Mpc −1 . These constraints complement the upper bound on the amplitude of the primordial power spectrum derived from limits on gamma-ray emission from UCMHs because the astrometric microlensing signal produced by an UCMH is maximized if the dark-matter annihilation rate is too low to affect the UCMH's density profile. If dark matter annihilation within UCMHs is not detectable, a search for UCMHs by Gaia could constrain the amplitude of the primordial power spectrum to be less than 10 −5 ; this bound is three orders of magnitude stronger than the bound derived from the absence of primordial black holes.

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“…The system includes 5 laser guide stars, 3 natural guide stars, 3 deformable mirrors optically conjugated at 0, 4.5 and 9km and 1 tip-tilt mirror. 4 The 4.5 km mirror was not in service at the time of our observations and was not implemented in the simulations.…”

Section: Hypotheses and Methodsmentioning

confidence: 98%

“…Besides, we add a known phase offset to avoid indetermination. First experiments on ONERA's test bench and on the calibration sources of GeMS, the multi-conjugate adaptive optics (MCAO) system of Gemini South Telescope, 4 have provided an in-lab validation of LIFT. 5,6 When using LIFT in an operational system, we will benefit from the correction of high orders thanks to laser guide stars.…”

Section: Introductionmentioning

confidence: 99%

LIFT: analysis of performance in a laser assisted adaptive optics

Plantet¹,

Meimon²,

Conan³

et al. 2014

SPIE Proceedings

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Laser assisted adaptive optics systems rely on Laser Guide Star (LGS) Wave-Front Sensors (WFS) for high order aberration measurements, and rely on Natural Guide Stars (NGS) WFS to complement the measurements on low orders such as tip-tilt and focus. The sky-coverage of the whole system is therefore related to the limiting magnitude of the NGS WFS.We have recently proposed LIFT, a novel phase retrieval WFS technique, that allows a 1 magnitude gain over the usually used 2×2 Shack-Hartmann WFS. After an in-lab validation, LIFT's concept has been demonstrated on sky in open loop on GeMS (the Gemini Multiconjugate adaptive optics System at Gemini South). To complete its validation, LIFT now needs to be operated in closed loop in a laser assisted adaptive optics system.The present work gives a detailed analysis of LIFT's behavior in presence of high order residuals and how to limit aliasing effects on the tip/tilt/focus estimation. Also, we study the high orders' impact on noise propagation. For this purpose, we simulate a multiconjugate adaptive optics loop representative of a GeMS-like 5 LGS configuration. The residual high orders are derived from a Fourier based simulation. We demonstrate that LIFT keeps a high performance gain over the Shack-Hartmann 2×2 whatever the turbulence conditions. Finally, we show the first simulation of a closed loop with LIFT estimating turbulent tip/tilt and focus residuals that could be induced by sodium layer's altitude variations.

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The Gemini MCAO System GeMS: nearing the end of a lab-story

Cited by 25 publications

References 19 publications

Identification and calibration of the interaction matrix parameters for AO and MCAO systems

Identification and calibration of the interaction matrix parameters for AO and MCAO systems

A new probe of the small-scale primordial power spectrum: Astrometric microlensing by ultracompact minihalos

LIFT: analysis of performance in a laser assisted adaptive optics

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