AO4ELT 2

Pathfinders to ELT AO at W.M. Keck Observatory

Peter WIZINOWICH — 2011-07-11T22:07:38Z

Submitted by Peter Wizinowich

Authors

Peter Wizinowich

Affiliations

W.M. Keck Observatory

Abstract

The Keck II AO system has been extremely productive scientifically with more than 300 refereed science papers including over 100 obtained with LGS AO. We will discuss lessons learned for ELT AO from the existing system and from the soon to be completed Keck I LGS AO system, as well as from pathfinder development efforts including a near-IR tip-tilt sensor, PSF reconstruction efforts and the Observatory's next generation AO system.

Integration, tests and laboratory performance of SAXO, the VLT-SPHERE extreme AO system

Cyril PETIT — 2011-05-16T20:00:36Z

submitted by C. Petit

Authors

C. Petit(1), T. Fusco(1), J.-F. Sauvage(1), A. Sevin(2), M. Suarez(3), J. Charton(4), P. Baudoz(2), J .-L. Beuzit(4), T. Buey(2), K. Dohlen(5), P. Feautrier(4), E. Fedrigo(3), B. Fleuzry(1), J.-L. Gach(5), N. Hubin(3), M. Kasper(3), D. Mouillet(4), D. Perret(2), P. Puget(4), J.-C. Sinquin(6), C. Soenke(3), F. Wildi(7)

Affiliations

(1) ONERA, (2) LESIA / Observatoire de Paris, (3) ESO, (4) IPAG / Observatoire de Grenoble, (5) LAM / Observatoire de Marseille, (6) CILAS, (7) Observatoire de Genève

Abstract

Direct detection and spectral characterization of extra-solar planets is one of the most exciting but also one of the most challenging areas in modern astronomy due to the very large contrast between the host star and the planet at very small angular separations. SPHERE (Spectro-Polarimetric High-contrast Exoplanet Research in Europe) is a second-generation instrument for the ESO VLT dedicated to this scientific objective. It combines an extreme adaptive optics system, various coronagraphic devices and a suite of focal instruments providing imaging, integral field spectroscopy and polarimetry capabilities in the visible and near-infrared spectral ranges.

The extreme AO system, SAXO, is the heart of the SPHERE system, providing to the scientific instruments a flat wavefront corrected from all the atmospheric turbulence and internal defects. We will present a status of SAXO assembly integration and performance. The main requirements and system characteristics will be recalled, then each sub system will be individually presented and fully characterized and finally the full AO loop performance will be quantified. It will be demonstrated that SAXO will meet its challenging requirements (more than 90% of SR in H band with a residual jitter lower than 3 milli-arcseconds for average observation conditions on the VLT). Thanks to a coronagraphic analysis of the AO residuals, a detailed comparison between actual and simulated residual intensity profiles will be provided and will help to adjust the expected performance of the SPHERE system on sky, knowing that its first light is foreseen for mid 2012.

Laser Tomographic AO system for an Integral Field Spectrograph on the E-ELT : the ATLAS project

Thierry FUSCO — 2011-05-16T20:00:28Z

submitted by T. Fusco

Authors

T. Fusco(1), S. Meimon(1), N. Thatte(2), H. Schnetler(3), Y. Clenet(4),M. Cohen(5), J. Paufique(6), P. Ammans(5), F. Clarke(2), J.-L. Dournaux(5), M. Ferrari(7), D. Gratadour(4), N. Hubin(6), P. Jagourel(5), V. Michau(1), C. Petit(1), M. Tecza(2)

Affiliations

(1) ONERA (2) Oxford Univ. (3) UK-ATC (4) Observatoire de Paris – GEPI (5) Observatoire de Paris – LESIA (6) ESO (7) Observatoire de Marseille – LAM

Abstract

ATLAS (Advanced Tomography with Laser for AO system) is the LTAO module of the E-ELT. It should be combined with an Integral Field Spectrograph (HARMONI). It aims at providing a diffraction limited PSF (SR around 50% in K band) in a small scientific FoV for a very significant part of the sky (more than 60% of the whole sky). 6 Laser Guide Stars (located on a 4.3 arcmin ring) will be used together with 2 Natural Guide Stars to be picked off in a 2 arcmin FoV. A MMSE-based RTC algorithm will be considered to obtain an optimal tomographic reconstruction of the turbulent volume and correct for Laser defects (cone effects). A first concept of the module combined with opto-mechanical implementation and associated performance has been proposed in the frame of the E-ELT instrumentation phase A study. Further modifications and optimisations have been proposed to account for IFS-HARMONI specificities.

In this presentation, the main ATLAS components are described and their specificities and innovation highlighted. In particular, a new concept for the natural guide star wavefront sensor (based on a focal plane measurement scheme) is proposed providing extremely good sky coverage. In addition, the impact of Cn² mis-calibrations is analyzed and solutions to mitigate this error are proposed.

In addition, the specific HARMONI requirements are presented as well as their impacts on ATLAS design, calibration procedures and operational concept. An integrated approach for a common implementation of ATLAS-HARMONI is presented. Results show the feasibility of the concept, its versatility and a relative simplicity which is a good first step toward a potential implementation in the early years of the E-ELT.

MOAO design, specificities and performance for EAGLE, the high resolution multi-object spectrograph for the E-ELT

Thierry FUSCO — 2011-05-16T20:00:01Z

submitted by T. Fusco

Authors

T. Fusco(1), G. Rousset(2), J.-G. Cuby(3), R. Myers(4), H. Schnetler(5), P. Jagourel(6) and the EAGLE team

Affiliations

(1) ONERA (2) Observatoire de Paris – LESIA (3) Observatoire de Marseille – LAM (4) University of Durham (5) UK-ATC (6) Observatoire de Paris – GEPI

Abstract

EAGLE is a wide-field multi IFU near-infrared (NIR) (IZ, YJ, H and K) spectrograph for use on the European Extremely Large Telescope (E-ELT). The instrument shall be capable of observing twenty science targets simultaneously and the atmospheric disturbances will be corrected by making use of an Adaptive Optics (AO) system.

The wide field, highly specialised AO system is the heart of the EAGLE concept. Due to the large field-of-view, a multi-object adaptive optics (MOAO) system will control the GLAO corrected field of the ELT (M4 and M5) with an additional Deformable Mirror in each channel of EAGLE. Six Laser Guide Stars and up to five Natural Guide Stars will be used to efficiently perform a tomographic analysis of the turbulent volume.

Based on the EAGLE MOAO system requirements, we have optimized the MOAO concept, and derive a residual wavefront error breakdown as part of the Phase A system design. The critical system choices are analysed and justified. Specific MOAO items are highlighted and it is shown that most of them allow us to reduce the overall system complexity with respect to some other wide field AO concepts. Finally, based on existing off-the-shelves components, current day technologic developments and on-going concept demonstrations (such as the CANARY MOAO experiment) we demonstrate that the EAGLE-MOAO concept has now reached a high level of maturity compatible with an aggressive development plan for an early deployment on the telescope in its first years of activity.

On-sky demonstration of focal plane wavefront sensing and quasi-static speckle suppression

Matthew KENWORTHY — 2009-02-28T23:00:00Z

Submitted by Matthew KENWORTHY

Authors

Matthew Kenworthy, Johanan Codona

Affiliations

Leiden Observatory, The Netherlands Steward Observatory, Tucson, AZ, USA

Abstract

Differences in the optical path of the science camera and the adaptive optics wavefront sensor give rise to slowly varying non common path errors, resulting in quasi-static speckles in the focal plane. These speckles limit the achievable contrast on current telescope and future ELTs for extrasolar planet detection and characterization.

We present on-sky results obtained at the MMTO 6.5m telescope in Arizona, where we have solved for the complex amplitude of the non common path error using short exposure high strehl science camera images and telemetry from the wavefront sensor camera using our Phase Sorting Interferometry technique. We can now reconstruct model point spread functions for each science camera frame and remove the quasistatic speckles out to several diffraction widths of the science camera PSF.

Design of the Laser Tomography Adaptive Optics System for the Giant Magellan Telescope

Rodolphe CONAN — 2009-02-28T23:00:00Z

Submitted by Rodolphe CONAN

Authors

R. Conan, B. Espeland, M. A. Van Dam, A. H. Bouchez

Affiliations

RSAA - ANU , Australia Flat Wavefronts, Christchurch, New Zealand Giant Magellan Telescope, Pasadena, USA

Abstract

The Laser Tomography Adaptive Optics (LTAO) system for the Giant Magellan Telescope (GMT) is currently in its Preliminary Design phase. The system design goals are to deliver at K band at least 50% ensquared energy in 50 milliarcsecond squared spaxels over 80% of the sky and to achieve better than 20% Strehl ratio in J band over 60% of the sky.

Both requirements are for a galactic latitude greater than 50 degrees. To reach these performance, the LTAO system will use 6 Laser guide stars (LGS) evenly located on a 30 arcsec ring centered on the science target. The measurements from the 6 Sodium LGS Shack—Hartmann wavefront sensors will drive the adaptive secondary mirror the actuator motions of which are derived from a minimum—mean square error tomographic reconstructor. A single infrared tip—tilt star will provide the science target tip—tilt correction. A dedicated deformable mirror in the tip—tilt path will correct the tip—tilt star wavefront aberrations.

The open—loop tip—tilt DM command will be derived from the tomographic reconstructor using the LGS WFS measurements. In addition to the tip—tilt sensor, a focus wavefront sensor combined with a zoom optics will keep the wavefront sensors [note: the telescope is always focused at infinity] focused on the mean altitude of the sodium layer and a high order wavefront sensor will track the so—called LGS aberrations and the system quasi static aberrations

The E-ELT Multi-Conjugate Adaptive Optics module

Emiliano DIOLAITI — 2009-02-28T23:00:00Z

Submitted by Emiliano DIOLAITI

Authors

E. Diolaiti (1), I. Foppiani (1,2), J.-M. Conan (3), R. C. Butler (4), R. I. Davies (5), A. Baruffolo (6), M. Bellazzini (1), G. Bregoli (1), P. Ciliegi (1), G. Cosentino (2), B. Delabre (7), T. Fusco (3), N. Hubin (7), M. Lombini (1,2), E. Marchetti (7), C. Petit (3), C. Robert (3), L. Schreiber (2)

Affiliations

(1) INAF – Osservatorio Astronomico di Bologna (Italy) (2) Università di Bologna – Dipartimento di Astronomia (Italy) (3) Office National d'Études et Recherches Aérospatiales (France) (4) INAF – Istituto di Astrofisica Spaziale e Fisica cosmica di Bologna (Italy) (5) Max Planck Institut fuer extraterrestrische Physik (Germany) (6) INAF – Osservatorio Astronomico di Padova (Italy) (7) European Southern Observatory (Germany)

Abstract

MAORY is the Multi-Conjugate Adaptive Optics (MCAO) module designed to work on the Nasmyth platform of the European Extremely Large Telescope (E-ELT). It relays the telescope focal plane to the science instrument and corrects the wavefront aberrations due to atmospheric turbulence and other disturbances such as telescope windshake. It provides a corrected field of 2 arcminutes on the wavelength range 0.8-2.4 µm. The module performance and design have been optimized for the client instrument MICADO (Multi-AO Imaging Camera for Deep Observations). A second output port to feed another instrument is available. The MCAO module corrects the wavefront using the telescope's adaptive mirror M4, optically conjugated to the ground layer and complemented by the tip-tilt mirror M5, and two deformable mirrors integrated in the module itself and conjugated to high altitude turbulent layers. The measurement of the wavefront distortions is performed by a suite of 6 Laser Guide Star WaveFront Sensors (LGSWFS) and 3 Natural Guide Star WaveFront Sensors (NGSWFS) for the measurement of the modes which cannot be properly sensed by the LGSWFS. In each NGSWFS probe the light is split in two beams: the longer wavelength light (1.5-1.8 micron) is used for fast sensing of low order modes, exploiting the image shrinking ensured by the MCAO loop, while the shorter wavelength light (0.6-0.9 micron) is used for sensing intermediate order aberrations at slower rate by means of a wavefront sensor with tunable pupil sampling. The MCAO system architecture is based on a robust closed-loop approach, which ensures reliable peak performance as well as good sky coverage. An overview of the module design and of the expected performance is given, addressing in particular the last results on the optical design and on the optimization of the NGSWFS performance closely related to sky coverage.

RAVEN, a Multi-Object Adaptive Optics technology and science demonstrator

David ANDERSEN — 2009-02-28T23:00:00Z

Submitted by Olivier LARDIèRE

Authors

Dave Andersen, Célia Blain, Colin Bradley, Darryl Gamroth, Meguru Ito, Kate Jackson, Olivier Lardière, Reston Nash, Shin Oya, Laurie Pham, Dave Robertson, Jean-Pierre Véran

Affiliations

Adaptive Optics Laboratory, Mechanical Engineering Department, University of Victoria, BC, Canada

Herzberg Institute of Astrophysics, NRC-CNRC, Victoria, BC, Canada

Subaru Telescope, Hilo, HI, USA

Abstract

The University of Victoria Adaptive Optics Laboratory, the Herzberg Institute of Astrophysics and Subaru Observatory are undertaking a preliminary design study for a Multi-Object Adaptive Optics (MOAO) technology and science demonstrator called Raven. Raven will be mounted on the Subaru NIR Nasmyth platform and will feed the IRCS imager and spectrograph. The baseline design calls for three natural guide star (NGS) wavefront sensors (WFS), one on-axis laser guide star (LGS) WFS and two science pickoff arms that will patrol a 2 arcminute diameter field of regard (FOR). Sky coverage is an important consideration for a science demonstrator. End-to-end simulations of Raven show that a 10x10 subaperture adaptive optics (AO) system can meet the science requirements, i.e. 30% of the energy ensquared (EE) within a 140mas slit using three R<14 NGSs, and 40% EE with the addition of the central LGS. An overview of the Raven project is presented, including the top-level requirements, science cases, opto-mechanical design, calibration procedures and the hardware and software architecture.

Novel Adaptive Optics on the Pathway to ELTs: MCAO with LINC-NIRVANA on LBT

Thomas HERBST — 2009-02-28T23:00:00Z

Submitted by Thomas HERBST

Authors

Tom Herbst, Roberto Ragazzoni, C. Arcidiacono, P. Bizenberger, M. Bergomi, T. Bertram, A. Brunelli, A. Conrad, F. D'Alessio, M. Dima, J. Farinato, G. Li Causi, D. Lorenzetti, V. Viotto, F. Vitali, X. Zhang

Affiliations

MPIA Heidelberg, INAF-Padova, INAF-Bologna

Abstract

LINC-NIRVANA is a near infrared interferometric imager that will achieve ELT-like spatial resolution for panoramic imagery on the Large Binocular Telescope (LBT). The LBT is a unique platform since its two, co-mounted 8.4 meter primary mirrors, coupled with fully adaptive secondary mirrors, present a time and view-direction- independent entrance pupil. This allows Fizeau-mode beam combination, giving 23-meter equivalent spatial resolution and the collecting area of a 12-m telescope.

In order to achieve diffraction limited image quality and maximum sky coverage, in particular for finding fringe-tracking reference stars, LINC-NIRVANA employs unique multi-conjugate adaptive optics (MCAO). The NIRVANA system comprises a total of five control loops for atmospheric turbulence: sequential ground and high-layer NGS AO correction for each telescope, coupled together through a common delay line to remove differential atmospheric piston and vibration. The MCAO operates in layer-oriented, multiple field-of-view mode with up to 12 ground-layer and 8 high-layer natural stars per telescope.

LINC-NIRVANA is a pathfinder for ELT instrumentation and AO systems in more ways than merely spatial resolution: in terms of physical size, complexity, alignment tolerances, and integration challenges, LINC-NIRVANA serves as an instructive precursor for future efforts.

In this presentation, we provide an update on the integration and testing of the instrument, including lab results on star acquisition and tracking, as well as loop performance, and plans for bringing the system online at the LBT.

NFIRAOS — Multiconjugate AO System for TMT

Glen HERRIOT — 2009-02-28T23:00:00Z

Submitted by Glen HERRIOT

Authors

Glen Herriot#, David Andersen#, Jenny Atwood#, Peter Byrnes#, Corinne Boyer*, Kris Caputa#, Carlos Correia#, Jennifer Dunn#, Brent Ellerbroek*, Joeleff Fitzsimmons#, Luc Gilles*, Paul Hickson$, Alexis Hill#, John Pazder#, Vlad Reshetov, Malcolm Smith#, Jean-Pierre Véran#, Lianqi Wang* , Ivan Wevers#

Affiliations

#NRC-HIA 5071 West Saanich Rd, Victoria, Canada. . *TMT 1111 S. Arroyo, Pasadena CA. $UBC 6224 Agricultural Road, Vancouver, Canada

Abstract

NFIRAOS, the Adaptive Optics system for the Thirty Meter Telescope, is a Multiconjugate Adaptive Optics System of order 60x60 with two deformable mirrors and six laser guide star wavefront sensors. NFIRAOS is 8 x 10 x 5 m (L x W x H) on a Nasmyth Platform and supports three client instruments operating over 0.8 – 2.5 µm wavelength range. In this paper we discuss: NFIRAOS' requirements and architecture; changes to NFIRAOS since the last AO4ELT conference; interior details of NFIRAOS; interfaces to instruments; integration and verification plans. Top-level science requirements include 50% sky coverage at the galactic pole with <187 nm wavefront error. Astrometry is an important science driver – to minimize image distortion, we have recently revised the optical design to use four off-axis paraboloidal mirrors. We have vastly simplified the laser WFS zoom optics and moved them inside the cold enclosure. To control image magnification, differential magnification and tip/tilt/focus, NFIRAOS' client instruments have three low-order warfront sensors monitoring near-infrared natural guide stars. These stars are sharpened by NFIRAOS, which assists sky coverage. NFIRAOS will have high throughput and low thermal background – it will be cooled to -30 °C. The insulated walls have a buried cold plate to intercept heat leakage and isothermalize the interior of NFIRAOS. Instruments have stringent requirements on heat leakage and must provide their own rotator and interface to NFIRAOS, including a rotating seal. For wavelength and flat field calibration of client instruments, a NFIRAOS Science Calibration Unit (NSCU) feeds light in the entrance window, through NFIRAOS, to instruments. Inside NFIRAOS are deployable light sources simulating natural and laser guide stars, a focal plane mask with pinholes illuminated by the NSCU, as well as a turbulence phase screen. A prototype screen has been manufactured by magneto-rheological machining. We are currently updating the NFIRAOS preliminary design.