AO4ELT 2

Optical Tube Assemblies for the ESO VLT Four Laser Guide Star Facility

Niek DOELMAN — 2011-09-08T13:39:28Z

Submitted by Fred Kamphues

Authors

R. Henselmans, D. Nijkerk, M. Lemmen, N.Rijnveld, N. Doelman, F.Kamphues

Affiliations

TNO

Abstract

ESO is implementing a new Adaptive Optics facility (AOF) on the Unit Telescope 4 (UT4) of the Very Large Telescope (VLT). For increased sky coverage, Four Laser Guide Star Facilities (4LGSF) will be installed. TNO is developing the Optical Tube Asssemblies (OTAs) for the 4LGSF.The OTAs are Galilean 20x beam expanders, expanding a ∅15 mm input beam to a steerable ∅300 mm output beam with a wavefront quality requirement of <50 nm rms. The allowed defocus under the influence of the changing environmental air temperature (0-15°C, -0.7°C/hr gradient) is only 0.2 waves. The thermal behaviour of the system has been analyzed by combining optical, lumped mass and FE analyses. The design is passively athermalized over a large temperature range as well as under the influence of thermal gradients. Extensive thermal and high power laser testing has shown the system performs as required. This poster describes the design and test results.

Predicted sky coverage for the TMT MCAO system NFIRAOS

David ANDERSEN — 2011-07-11T22:12:11Z

Authors

David Andersen, Lianqi Wang, Brent Ellerbroek, Glen Herriot

Affiliations

NRC HIA, TMT

Abstract

TMT has chosen the MCAO system NFIRAOS to be its first light AO system in part to provide astronomers with exceptional sky coverage. The TMT science requirements demand that its AO system provide wavefront errors of less than or equal to 191 nm at the galactic pole at least 50% of the time (under median atmospheric conditions when observing at zenith). This requirement drove many aspects of the NFIRAOS design from the size of the FOV, to the use of NIR MCAO-corrected NGSs, to the sensitivity of the WFSs (and corresponding limiting magnitude of the NGSs). In this paper, we build upon the sky coverage simulations of L. Wang et al. to produce smooth sky coverage maps generated for different hour angles (potential exposure time lengths), and different atmospheric conditions. We show that NFIRAOS should meet its sky coverage requirement at the North Galactic Pole, and that the sky coverage generally will be much higher than 50% at lower galactic latitudes.

Design of the calibration unit for the MOAO demonstrator Raven

Jean-françois LAVIGNE — 2011-07-11T22:10:34Z

Authors

Jean-François Lavigne, Frédéric Lamontagne, Min Wang, Marc-André Boucher

Affiliations

Institut national d'optique

Abstract

The UVic AO Lab in collaboration with HIA and the Subaru telescope is currently designing Raven, a multi-object adaptive optics (MOAO) demonstrator that will be coupled to the Subaru Infrared Camera and Spectrograph (IRCS). Its main goal will be to demonstrate MOAO feasibility on the sky while allowing astronomers to beneficiate from the increased observing efficiency associated with such systems.

Raven will use three natural guide stars (NGS) or two natural guide stars and Subaru laser guide star (LGS) to do the tomographic reconstruction of the atmosphere turbulence. The appropriate correction will then be applied to two science fields that will feed IRCS. The wavelengths between 0.6 and 0.9 µm will be used for the wavefront sensing while the science wavelengths between 0.9 and 2.5 µm will be directed towards IRCS.

INO is currently designing the Raven calibration unit. This sub-system consists in a telescope simulator that will allow aligning Raven components during its integration, testing its AO performances in the laboratory or at the telescope and calibrating the AO system by building the interaction matrix and measuring the non-common path aberrations (NCPA).

The calibration unit will provide a 9x9 grid of broadband (0.6 to 2.5 µm) NGS sources diffraction limited above 1.0 µm and located in a 2.7' circular FoV. It will allow to vary the NGS sources intensity to emulate stars ranging from R=8 to R=16. An on-axis LGS that can be conjugated to altitudes varying from 85 km to 180 km and intensity ranging from R=5 to R=11 will also be simulated. An on-axis bright white source conjugated to infinity will be installed for the user to see the beam during alignment. The calibration unit will include two deployable phase screens conjugated at altitudes of 5 km and 11 km and a deformable mirror conjugated to the ground.

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.

Palm-3000 on-sky results

Richard DEKANY — 2011-07-05T09:44:17Z

Submitted by R. Dekany

Authors

Dekany, R. (1), Roberts, J. (2), Burruss, R. (2), Truong, T. (2), Palmer, D. (2), Guiwits, S. (2,1), Hale, D. (1), Angione, J. (2), Baranec, C. (1), Croner, E. (1), Davis, J. T. C. (1), Zolkower, J. (1), Henning, J. (1), McKenna, D. (1), and Bouchez, A. H. (1)

Affiliations

1 Caltech Optical Observatories, California Institute of Technology, Pasadena, CA 91125

2 Jet Propulsion Laboratory, California Institute of Technology, Pasadena, CA 91109

Abstract

PALM-3000, the second-generation facility adaptive optics system for the 5-meter telescope at Palomar Observatory, successfully obtained first high-order correction on sky on UT June 21, 2011. Within PALM-3000, low-order wavefront correction is applied with a Xinetics, Inc. 349 (241 active) actuator deformable mirror reused from the 1999 PALAO system. High-order correction is applied with a new Xinetics, Inc. 4,356 (3,388 active) actuator deformable mirror based upon a 6 x 6 array of 11 x 11 actuator Photonex modules. The system also uses a new CCD50-based Shack-Hartmann wavefront sensor camera and a novel real-time computer based upon a bank of commercial GPU's. Currently, the first of four planned wavefront sensor pupil sampling modes (N = 64 subapertures per pupil) has been tested, emphasizing early high-contrast exoplanet science with the PHARO coronagraphic imager and P1640 coronagraphic integral field spectrograph. We report on AO correction performance to date and our experience with the unique 66 x 66 actuator Xinetics, Inc. DM, as well as describe the PALM-3000 commissioning program and future plans.

Review of the GMT AO program

Antonin BOUCHEZ — 2011-07-05T09:42:49Z

Submitted by A. Bouchez

Authors

Antonin Bouchez

Affiliations

Giant Magellan Telescope

Abstract

TBD

Gemini South MCAO on-sky results

Francois RIGAUT — 2011-07-05T09:28:34Z

Submitted by F. Rigaut

Authors

François Rigaut

Affiliations

Gemini Observatory

Abstract

TBD

Toward the Adaptive Optics for the 40 m class European ELT

Norbert HUBIN — 2011-06-17T09:47:50Z

Submitted by N. Hubin

Authors

Norbert Hubin

Affiliations

ESO

Abstract

This paper will provide an overview of the recent pathfinders, technology developments and concept studies made in preparation of the construction of the Adaptive Optics facilities for the 40-m class European ELT. This paper will also focus on the progresses, challenges and remaining risks of the AO key technologies and concepts and will present an enabling technology roadmap to mitigate these risks in close cooperation with the ESO community and industry.

The TMT Adaptive Optics Program

Brent ELLERBROEK — 2011-06-15T08:34:21Z

Submitted by B. Ellerbroek

Authors

Brent Ellerbroek

Affiliations

TMT Observatory Corporation

Abstract

We provide an overview of the Thirty Meter Telescope (TMT) AO program, with an emphasis upon the progress made since the first AO4ELT conference held in 2009.

The first light facility AO system for TMT is the Narrow Field Infra-Red AO System (NFIRAOS), which will provide diffraction-limited performance in the J, H, and K bands over 18-30 arc sec diameter fields with 50% sky coverage at the galactic pole. This is accomplished with order 60x60 wavefront sensing and correction, two deformable mirrors conjugate to ranges of 0 and 11.2 km, 6 sodium laser guide stars in an asterism with a diameter of 70 arc sec, and three low order (tip/tilt or tip/tilt focus), infra-red natural guide star (NGS) wavefront sensors deployable within a 2 arc minute diameter patrol field. The first light LGS asterism is generated by the Laser Guide Star Facility (LGSF), which initially incorporates 6 20-25W class laser systems mounted to the telescope elevation journal, a mirror-based beam transfer optics system, and a 0.4m diameter laser launch telescope located behind the TMT secondary mirror.

Future plans for additional AO capabilities include a mid infra-red AO (MIRAO) system to support science instruments in the 4-20 micron range, a ground-layer AO (GLAO) system for wide-field spectroscopy, a multi-object AO (MOAO) system for multi-object integral field unit spectroscopy, and extreme AO (ExAO) for high contrast imaging.

Significant progress has been made in developing the first-light AO architecture since 2009. This includes the adoption of a new NFIRAOS opto-mechanical design consisting of two off-axis parabola (OAP) relays in series, which eliminates field distortion and also significantly simplifies the designs of the LGS wavefront sensors, optical source simulators, and turbulence generator subsystem. The design of the LGSF has also been interated, and has been simplfied by the relocation of the (smaller, gravity invarient) laser systems to the telescope elevation journal.

Protoyping activities continue for laser systems, wavefront sensing detectors, and deformable mirrors; work on the associated detector and deformable mirror electronics has also been initiated. AO Performance estimates and error budgets have been further detailed. Some of the modeling topics which have received particular attention include turbulence (Cn2) profile estimation from LGS WFS measurements, sodium layer range tracking, PSF reconstruction for multi-conjugate AO, LGS fratricide, astrometry at the galactic center, and further optimizing sky coverage and the peformance of the tip/tilt and low-order NGS mode control loops. Finally, experiments and field tests continue at the University of British Columbia LIDAR facility to measure the spatial and temporal variability of the sodium layer, and to characterize the sodium coupling efficiency of candidate laser systems for TMT.

Extreme is the new normal: lessons from 8-m ExAO for ELT regular AO

Bruce MACINTOSH, Jean-Luc BEUZIT — 2011-06-15T08:23:51Z

Submitted by B. Macintosh

Authors

B. Macintosh (1), J.-L. Beuzit (2)

Affiliations

(1) Lawrence Livermore National Laboratory, (2) IPAG

Abstract

The first true extreme adaptive optics (ExAO) instruments for 8-m telescopes are nearing completion - SPHERE for the Very Large Telescope, and the Gemini Planet Imager for Gemini South. With N=40 to 44 subapertures across the telescope, these high-performance systems represent an important step towards the N=60+ systems that will be needed for general-purpose AO on ELTs. GPI and SPHERE each incorporate many key technologies - high-density deformable mirrors, computationally efficient advanced wavefront control algorithms, zero-noise CCDs, multi-stage wavefront correction, new calibration algorithms, etc. - that will have to be incoprorated into the ELT facilities. We will review these features and the status of the two instruments, and the lessons learned for the design of ELT AO, both normal and extreme