NAOMI: a low-order adaptive optics system for the VLT interferometer

Gonté, Frederic; Alonso, Jaime; Aller-Carpentier, Emmanuel; Andolfato, Luigi; Berger, J.‐P.; Cortes, Angela; Delplancke-Ströbele, F.; Donaldson, Rob; Dorn, Reinhold J.; Dupuy, Christophe; Egner, Sebastian; Huber, Stefan; Hubin, N.; Kirchbauer, Jean-Paul; Louarn, Miska Le; Lilley, Paul; Jolley, Paul; Martis, Alessandro; Paufique, J.; Pasquini, L.; Quentin, J.; Ridings, R.; Reyes, Javier Escalera; Shchkaturov, Pavel; Suárez, M.; Duc, Thanh Phan; Valdes, G.; Woillez, J.; Bouquin, Jean-Baptiste Le; Beuzit, Jean-Luc; Rochat, S.; Vérinaud, Christophe; Moulin, T.; Delboulbé, A.; Michaud, L.; Correia, Jean-Jacques; Roux, A.; Maurel, D.; Stadler, Eric; Magnard, Y.

doi:10.1117/12.2233993

Cited by 4 publications

(7 citation statements)

References 2 publications

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“…This situation led to the decision to retire the single field interface between the ATs and VLTI, keeping the star separators as the only interface. This decision simplifies the operations of VLTI (there is no need to reconfigure), and the development of NAOMI [2] (to only support the star separators).…”

Section: : Measured Transmission Of the At And Ut Telescopes In Visimentioning

confidence: 99%

“…The fringe tracking performance is severely impacted. The NAOMI [2] adaptive optics will be able to correct this turbulence very efficiently. The best Paranal nights, with low wind and excellent seeing, will then be accessible by VLTI.…”

Section: The Next Step: Naomimentioning

confidence: 99%

“…The NAOMI adaptive optics, presented in greater details by Gonté et al [2] , are expected to be installed on all four ATs by late 2018.…”

Section: The Next Step: Naomimentioning

confidence: 99%

“…This was necessary to perform a functional upgrade of the infrastructure and prepare the arrival of the next generation instruments. These changes are presented in detail by Gonté et al [1] , and involve: the construction of a new maintenance station for the Auxiliary Telescope (AT), to facilitate the future installation of NAOMI [2] on the ATs and support the increased uptime requirement from the 4T instruments (PIONIER [3] , Gravity [4] , MATISSE [5] ), the decommissioning of MIDI [6] and PRIMA FSU [7] and relocation of PIONIER [3] in order to make room for Gravity [4] and MATISSE [5] , the upgrade of the Interferometric and Combined Coudé laboratories with new cooling, power, network, and cryogenic supply lines, the installation of star separators on AT1 and AT2 (AT3 and AT4 had already been equipped by the PRIMA facility project [8] ). This transformation of the AT array was completed in time for the installation of the Gravity beam combiner in October 2015.…”

Section: Introductionmentioning

confidence: 99%

“…The M4 to M8 mirrors are the exact same telescope optics with which first lights was achieved over 10 years ago [13] . Table 1 summarizes the impact on the visible transmission (AT4 being the worst), which is at an unacceptable level for NAOMI [2] , the future AO system of the ATs (see section 2.3). In consequence, a complete replacement of the Coudé train has been scheduled between the end of 2016 and the beginning of 2017.…”

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confidence: 99%

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The 2nd generation VLTI path to performance

et al. 2016

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The upgrade of the VLTI infrastructure for the 2 nd generation instruments is now complete with the transformation of the laboratory, and installation of star separators on both the 1.8-m Auxiliary Telescopes (ATs) and the 8-m Unit Telescopes (UTs). The Gravity fringe tracker has had a full semester of commissioning on the ATs, and a first look at the UTs. The CIAO infrared wavefront sensor is about to demonstrate its performance relative to the visible wavefront sensor MACAO. First astrometric measurements on the ATs and astrometric qualification of the UTs are on-going. Now is a good time to revisit the performance roadmap for VLTI that was initiated in 2014, which aimed at coherently driving the developments of the interferometer, and especially its performance, in support to the new generation of instruments: Gravity and MATISSE.

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Section: : Measured Transmission Of the At And Ut Telescopes In Visimentioning

confidence: 99%

Section: The Next Step: Naomimentioning

confidence: 99%

“…The NAOMI adaptive optics, presented in greater details by Gonté et al [2] , are expected to be installed on all four ATs by late 2018.…”

Section: The Next Step: Naomimentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

mentioning

confidence: 99%

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The 2nd generation VLTI path to performance

et al. 2016

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First light for GRAVITY: Phase referencing optical interferometry for the Very Large Telescope Interferometer

Abuter¹,

Accardo²,

Amorim³

et al. 2017

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407

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GRAVITY is a new instrument to coherently combine the light of the European Southern Observatory Very Large Telescope Interferometer to form a telescope with an equivalent 130 m diameter angular resolution and a collecting area of 200 m 2 . The instrument comprises fiber fed integrated optics beam combination, high resolution spectroscopy, built-in beam analysis and control, near-infrared wavefront sensing, phasetracking, dual-beam operation, and laser metrology. GRAVITY opens up to optical/infrared interferometry the techniques of phase referenced imaging and narrow angle astrometry, in many aspects following the concepts of radio interferometry. This article gives an overview of GRAVITY and reports on the performance and the first astronomical observations during commissioning in 2015/16. We demonstrate phase-tracking on stars as faint as m K ≈ 10 mag, phase-referenced interferometry of objects fainter than m K ≈ 15 mag with a limiting magnitude of m K ≈ 17 mag, minute long coherent integrations, a visibility accuracy of better than 0.25%, and spectro-differential phase and closure phase accuracy better than 0.5• , corresponding to a differential astrometric precision of better than ten microarcseconds (µas). The dual-beam astrometry, measuring the phase difference of two objects with laser metrology, is still under commissioning. First observations show residuals as low as 50 µas when following objects over several months. We illustrate the instrument performance with the observations of archetypical objects for the different instrument modes. Examples include the Galactic center supermassive black hole and its fast orbiting star S2 for phase referenced dual-beam observations and infrared wavefront sensing, the high mass X-ray binary BP Cru and the active galactic nucleus of PDS 456 for a few µas spectro-differential astrometry, the T Tauri star S CrA for a spectro-differential visibility analysis, ξ Tel and 24 Cap for high accuracy visibility observations, and η Car for interferometric imaging with GRAVITY.

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Methods for multiple-telescope beam imaging and guiding in the near-infrared

Anugu

Amorim

Gordo

et al. 2018

Monthly Notices of the Royal Astronomical Society

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Atmospheric turbulence and precise measurement of the astrometric baseline vector between any two telescopes are two major challenges in implementing phase referenced interferometric astrometry and imaging. They limit the performance of a fibre-fed interferometer by degrading the instrument sensitivity and astrometric measurements precision and by introducing image reconstruction errors due to inaccurate phases. A multiple beam acquisition and guiding camera was built to meet these challenges for a recently commissioned four beam combiner instrument, GRAVITY, at the ESO Very Large Telescope Interferometer. For each telescope beam it measures: a) field tip-tilts by imaging stars in the sky; b) telescope pupil shifts by imaging pupil reference laser beacons installed on each telescope using a 2 × 2 lenslet; c) higher order aberrations using a 9 × 9 Shack-Hartmann. The telescope pupils are imaged for a visual monitoring while observing. These measurements enable active field and pupil guiding by actuating a train of tip-tilt mirrors placed in the pupil and field planes, respectively. The Shack-Hartmann measured quasi-static aberrations are used to focus the Auxiliary Telescopes and allow the possibility of correcting the non-common path errors between the Unit Telescopes adaptive optics systems and GRAVITY. The guiding stabilizes light injection into single-mode fibres, increasing sensitivity and reducing the astrometric and image reconstruction errors. The beam guiding enables to achieve astrometric error less than 50 µas. Here, we report on the data reduction methods and laboratory tests of the multiple beam acquisition and guiding camera and its performance on-sky.

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NAOMI: a low-order adaptive optics system for the VLT interferometer

Cited by 4 publications

References 2 publications

The 2nd generation VLTI path to performance

The 2nd generation VLTI path to performance

First light for GRAVITY: Phase referencing optical interferometry for the Very Large Telescope Interferometer

Methods for multiple-telescope beam imaging and guiding in the near-infrared

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