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Many of the proposed science cases for extremely large telescopes (ELT) are only possible because of the unprecedented sensitivity and spatial resolution due to advanced, e.g. tomographic and multi conjugate, adaptive optic (AO) systems. Current AO systems on 8-10m telescopes work best at wavelengths longward of 1 micro-m with Strehl ratios >= 15 per cent. At red-optical wavelengths, e.g. in the I band (0:8 micro-m), the Strehl ratio is at best a few percent. The AO point spread function (PSF) typically has a diffraction-limited core superimposed on the seeing halo, however, for a 5% Strehl ratio the core has a very low intensity above the seeing halo. At an ELT, due to a 3-4 times higher angular resolution, the diffraction limited PSF core of only 5% Strehl ratio stands more prominently atop the shallow seeing halo leading to almost diffraction limited image quality even at low Strehl ratios. Prominent ELT science cases that use the Calcium triplet can exploit this gain in spatial resolution in the red-optical: stellar populations in dense environments or crowded fields; and the case of intermediate mass black holes in nuclear and globular stellar clusters, as well as (super-) massive black holes in galaxies.

International audience; We present deep Ks band Gemini GeMS/GSAOI observations of Westerlund 1, the most massive young Galactic star cluster known. The high spatial resolution combined with a relatively stable point spread function across a large field of view provide unique possibilities to resolve the low-mass content of the cluster. We show that the clean point spread function is crucial in handling the source detection in this crowded field suffering extremely high contrast from the brightest hypergiants in the cluster to faint brown dwarfs.

Direct imaging is a powerful tool for exoplanet atmosphere characterization. High performance of these techniques requires extreme wavefront correction for ground-based instruments as well as space projects. Wavefront sensors are usually physically separated from the common optics by a beam splitter in classical AO system. This separation introduces differential aberrations that are not measured by the wavefront sensor, which limits the performance of a planet finder instrument. We propose to use the Self-Coherent Camera (SCC) to measure the aberrations directly in the final coronagraphic science focal plane. The SCC is based on the principle of light coherence and allows us to estimate the wavefront errors upstream the coronagraph by spatially encoding the speckles with fringes in the final image. After recalling the SCC principle, we will present laboratory results on speckle suppression and compare them with expected performances from numerical simulations., 2nd International Conference on Adaptive Optics for Extremely Large Telescopes, AO for ELT 2011, September 25-30, 2011, Victoria, BC Canada

The Giant Magellan Telescope adaptive optics system will be an integral part of the telescope, providing laser guide star generation, wavefront sensing, and wavefront correction to most of the currently envisioned instruments. The system will provide three observing modes: Natural Guidestar AO, Laser Tomographic AO, and Ground Layer AO. All three modes will use the telescope’s segmented adaptive secondary mirror to deliver a corrected beam directly to the instrument foci. We will describe the system requirements, overall architecture, and innovative solutions found to the challenges presentedby high-order AO on a segmented extremely large telescope. The GMT AO system is currently in the preliminary design phase, and is expected to see first light in 2020.

In this article, simulation results are presented for an extreme adaptive optics (order 200x200 sub-apertures) system, using a Pyramid WFS. These end-to-end simulations show that such a system is tractable with current simulation software and hardware. We also demonstrate that a novel reconstruction algorithm – CuRe – can provide similar performance (at much lower computational cost) than our standard Matrix Vector Multiply.

The University of Victoria Adaptive Optics Laboratory, the Herzberg Institute of Astrophysics and Subaru Observatory are building 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 3.5 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 per cent of the energy ensquared (EE) within a 140mas slit using three R less than 14 NGSs, and almost 40 per cent EE with the addition of the central LGS. We present here an overview of the Raven project.

In this paper we present quantitative results that show the superior sensitivity of the non-linear curvature wavefront sensor (nlCWFS) compared to the Shack-Hartmann wavefront sensor (SHWFS) and the modulated pyramid wavefront sensor (MPYWFS) for low and high order aberrations. We explain the design for the chromatic re-imaging optics (CRO) that introduces chromatic compensation which prevents broad band speckles from suffering chromatic aberration. We show results from the CRO built for one of the four channels of the nlCWFS design.

The Durham High-order Demonstrator (DHD) is a proposed high-order/extreme adaptive optics instrument design for the 4.2m William Herschel Telescope on La Palma, Canary Islands. Our principal interest in this instrument is designing a flexible-testbed for which we can develop a high-order AO system which is suitable for diffraction-limited, visible-light imaging. Additionally, it then becomes a facility which provides a high-order AO corrected beam for further instrument development such as coronography and thus XAO applications. This paper shows our instrument design and the limiting performance estimates. Part of the high-order wavefront sensing is provided by a second interferometric wavefront sensor of novel design to characterise the PSF and resolve quasi-static aberrations to prevent persistent speckle.

EAGLE is a near-infrared wide field multi object spectrograph. It includes its own Multi-Object Adaptive Optics system (MOAO) and its subsystems are cooled to deliver the performance in the K-band. Due to the integrated nature of the instrument, the performance matrix has to deal with a large number of Adaptive Optics (AO) parameters as well as the added complexity of active optical elements. To ensure successful integration of the next generation instruments for ELT like EAGLE, it is of the utmost importance to have method to control and manage the instrument’s critical performance characteristics. We discuss the performance matrix we developed to automatically partition and allocate the important characteristics to the various subsystems as well as the process to verify that the concept will deliver the required performance. We also define a method to convert the ensquared energy and signal-to-noise ratio into the “as designed” overall residue wavefront error.

ATLAS is a generic Laser Tomographic AO (LTAO) system for the E-ELT. Based on modular, relatively simple, and yet innovative concepts, it aims at providing diffraction limited images in the near infra-red for a close to 100 percent sky coverage.

The application of laser guide stars to large aperture telescopes has spurred many new studies in wavefront sensing. For the particular case of the Shack-HartmannWFS, wavefront sensing is prone to new sources of errors not previously considered. The primary source of error is spot elongation resulting from the resolution of the finite thickness of the sodium layer. The elongation spreads the signal over several pixels, resulting in a decrease of the signal to noise ratio and an increase of non-linearity. Also, the SHWFS performance becomes sensitive to temporal and spatial variations of the density of the sodium atoms. Among the different centroid algorithms to be used with this WFS, the most powerful methods (correlation, matched filter, WCoG) require a reference. Although straightforward for a point source, the use of a resolved laser guide star is more cumbersome because the sodium layer variations affect their performance. In this paper we look at the impact of the sodium layer fluctuations and the reference choice on the performance of the WFS, considering real as well as analytical non-symmetric profiles, and investigating both the subaperture level and the wavefront reconstruction level. We conclude on the compromise between the use of the best possible reference versus the difficulty of implementation.

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 present a status of SAXO assembly integration and testing. The main AO system characteristics are recalled, then each sub system is individually presented and characterized. In the end, SAXO shall 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). Assessment of the performance shall be performed in a near future, but we propose first results of the AO system in its current status.

Present and future adaptive optics systems aim for the correction of the atmospheric turbulence over a large field of view combined with large sky coverage. Thus they use multiple laser beacons on sky. Still usually a guide star for correction of the tilt-aberrations is needed. For some fields even a tilt-star is not available. To still be able to improve the image quality the laser beacons must not be affected by telescope vibrations on their up-link path. For the ARGOS system the jitter of the beacons must be below 0".05. To achieve this a vibration compensation system is necessary which runs at high speed. In this article the control algorithm for this system and first laboratory tests of the algorithm are presented.

Raven is a MOAO demonstrator that will be mounted on the Nasmyth platform of the Subaru telescope and is intended to serve as a pathfinder for future ELT MOAO instruments.We present the Raven wavefront error budget that was used to define the AO architecture. In particular, we focus here on recent simulations of Raven performance for real science targets, and performance as a function of zenith angle. We show that Raven should deliver >= 30 % ensquared energy in a 140 mas slit under median conditions.

The next generation of adaptive optics (AO) systems require tomographic techniques in order to correct for atmospheric turbulence along lines of sight separated from the guide stars. Multi-object adaptive optics (MOAO) is one such technique. Here, we present a method which uses an artificial neural network (ANN) to reconstruct the target phase given off-axis references sources. This method does not require any input of the turbulence profile and is therefore less susceptible to changing conditions than some existing methods. We compare our ANN method with a standard least squares type matrix multiplication method (MVM) in simulation and find that the tomographic error is similar to the MVM method. In changing conditions the tomographic error increases for MVM but remains constant with the ANN model and no large matrix inversions are required.

The direct exoplanet imaging field will strongly benefit from the higher angular resolution achieved by next generation 30+m telescopes. To fully take advantage of these new facilities, one of the biggest challenges that ground-based adaptive optics imaging must overcome is to derive accurate astrometry and photometry of point sources. The planet photometry and its astrometry are used to compare with atmospheric models and to fit orbits. If erroneous numbers are found, or if errors are underestimated, spurious fits can lead to unphysical planet characteristics or wrong/unstable orbits. Overestimating the errors also needs to be avoided as it degrades the value of the data. Several photometry/astrometry biases that are induced by advance imaging and processing techniques (such as ADI/SSDI/LOCI) are presented as well as a procedure to properly overcome those effects. These solutions will be implemented in the Gemini Planet Imager campaign data pipeline and it is expected that they will also play a crucial role in any future direct exoplanet imaging survey., 2nd International Conference on Adaptive Optics for Extremely Large Telescopes, AO for ELT 2011, September 25-30, 2011, Victoria, BC Canada

This paper presents a linear quadratic Gaussian (LQG) command based design approach for the con- trol of an astronomical adaptive optics system. In this framework, the control uses the state-feedback of the atmospheric distortion wavefront estimate. Such estimate is obtained from a Kalman filter which incorporates a model of the atmospheric distortion wavefront. During on-sky observations, strength of the atmospheric turbulence and wind velocity of each turbulent layer can change rapidly, degrading the atmospheric distortion wavefront estimate. We derive a numerical procedure in order to obtain a model of the atmospheric distortion wavefront which guarantees satisfactory disturbance rejection performance in despite of turbulence variations. Numerical experiments using the Software Package CAOS have been conducted to demonstrate the robustness of the proposed approach.

DRAGON is the Durham University astronomical adaptive optics test-bench, designed to accurately simulate the effects of the atmosphere for the purposes of developing high-order adaptive optics, but principally targeted towards visible AO correction for current telescopes. The design consists of altitude adjustable phase screens, a synthetic sodium guide star and a set of fixed targets that can also be used as natural guide stars. The design has been optimised for both wide-field (2.5′ FoV, hence MCAO/MOAO) and on-axis (SCAO) situations with 4–8m telescopes. Since it is targeted toward visible AO, high order wavefront sensing and correction are obvious steps towards ELT-scale AO development and a key aspect of DRAGON is the integration of the Durham RTC system. The design of DRAGON is discussed and its extensions towards simulating ELT scale AO in its current configuration are explained.

Adaptive optics (AO) systems correct for atmospheric distortion in real time in order to produce sharper images and enhance scientific capabilities. Sky coverage is greatly increased by the use of laser guide stars generated by resonant excitation of mesospheric sodium atoms. However, physical processes in the upper atmosphere affect the performance of such systems. Competing processes of meteoric ablation that produce, and chemical reactions that remove, sodium atoms, govern the extent and density of the sodium region. The structure of this region is affected by gravity waves, wind shear and turbulence that cause temporal and spatial density variations and thus affect the mean sodium altitude and consequently produce focus-induced wavefront errors, degrading AO performance. In order to better quantify these effects, we developed a high-performance sodium lidar system for the 6-m Large Zenith Telescope. With a power-aperture product more than two orders of magnitude greater than most atmospheric lidar systems, the facility is capable of recording sodium density profiles with sub-second and meter-scale resolution. A recent upgrade enables us to simulate laser guide star asterisms and directly measure horizontal structure variations by chopping a pulsed laser beam horizontally within the 1 arcmin field of view. The 2d mean altitude structure function shows the variance in variation is hence linked to differential focus errors, an important aspect for multi-laser guide star facilities and multi-object adaptive optics.

LINC-NIRVANA is an imaging Fizeau interferometer, for use in near infrared wavelengths, being built for the Large Binocular Telescope. Multi-conjugate adaptive optics (MCAO) increases the sky coverage and the field of view over which diffraction limited images can be obtained. For its MCAO implementation, Linc-Nirvana utilizes four total wavefront sensors; each of the two beams is corrected by both a ground-layer wavefront sensor (GWS) and a high-layer wavefront sensor (HWS). The GWS controls the adaptive secondary deformable mirror (DM), which is based on an DSP slope computing unit. Whereas the HWS controls an internal DM via computations provided by an off-the-shelf multi-core Linux system. Using wavefront sensor data collected from a prior lab experiment, we have shown via simulation that the Linux based system is sufficient to operate at 1 kHz, with jitter well below the needs of the final system. Based on that setup we implemented an adaptive optics loop control application which includes the back-end number crunching loop pipeline from camera readout to the DM. All intermediate steps of the loop are controlled by modular engineering GUI front- ends for diagnostic and configuration. Those engineering front-ends can either be used together with the slope computing unit (Basic Computation Unit BCU) which is used by the GWS and the initial Pathfinder setup or with the Linux based system (for MCAO operation of the HWS). The implementation of the Linux based system is done similar to the internal process of the BCU. In this way both systems provide the same functionalities and can be maintained more easily.

Here we adjust traditional definitions of atmospheric time constant and isoplanatic angle to make them more useful for adaptive optics and interferometry and, at the same time, easier to measure.

Wide Field Adaptive Optics (WFAO) systems require a precise reconstruction of the turbulent volume. The C2n profile, representing the turbulence strength, becomes a critical parameter for the final tomographic reconstruction performance. We present a new method, CO-SLIDAR (COupled SLope and scIntillation Detection And Ranging), that uses correlations of slopes and scintillation indexes recorded on a Shack-Hartmann (SH), to retrieve the C2n profile. A design is proposed for the instrument. Reconstruction performances are showed in simulation. Tests are carried out on the optical bench, and improvements are suggested. Sensitivity of the method to outer scale is demonstrated.

SAMI, the SCAO module for the E-ELT imaging camera MICADO, could be used in the first years of operation of MICADO on the telescope, until MAORY is fully operational. We present the results of the study made in the framework of the MICADO phase A to design and estimate the performance of this SCAO module.

Updated results obtained from simulations of a single-conjugated adaptive optics (SCAO) system for a 42 m telescope are presented in this work. The modulated pyramid wavefront sensor (PWFS), which has been preferred in some projects for its versatility and sensitivity, is used in these simulations. The main objective of this work is to evaluate the performance of such SCAO system under different parameters (loop gain, modulation, truncated SVD mode), sensing wavelengths, atmospheric coherence lengths and NGS magnitudes. Always measuring the Strehl ratio in the K-band, we have verified that the overall performance tends to be poorer as the sensing wavelength becomes shorter. The loop gain optimal range is dependent on the SVD truncation threshold used to build the command matrix, and a nonmodulated PWFS produces in general poorer results when compared to modulated cases, being this especially true for the R-sensing band. The default atmospheric model adopted was a von Kárman with r0=0.13 m (@ 500 nm) and outer scale of 25 m, but poorer and better seeing conditions have also been tested. We also show how the Strehl is affected by the incidence of different photon fluxes at the PWFS detector and by the system working in different frame rates.

CANARY has been designed to demonstrate full tomographic LGS MOAO in a configuration as close as possible to that of the proposed EAGLE instrument for the E-ELT. A phased approach to the instrument development has been adopted to reduce the overall risk and developmental complexity with the initial Phase A system performing NGS MOAO only using three off-axis NGS WFS. The Phase B system will add four off- axis open-loop LGS WFSs to this system allowing combined LGS/NGS tomography to be performed, thereby taking CANARY one step closer to an EAGLE-like configuration. The upgrade to include LGS within CANARY requires several new and upgrades subsystems, including a multiple LGS launch system, LGS WFSs and a new LGS calibration unit. Here we present the requirements, design, and subsystem performance for the Phase B system, as well as simulations of the on-sky AO performance of CANARY Phase B.

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.

The Altair AO system at Gemini North has been in regular operation since 2004 in NGS mode. Over the past few years we have been routinely monitoring its performance looking at the telemetry in the form of circular buffers from the nightly tuning, in particular the residual tip-tilt (TT). We present analysis of these data which illustrate how the instrument support structure (ISS) environment affects the residual TT and how different components of the TT signal are affected by the instrument compliment.

The future large telescopes will be certainly equipped with Multi-Conjugate Adaptive Optics systems. The optimization of the performances of these techniques requires a precise specification of the different components of these systems. Major of these technical specifications are related to the atmospheric turbulence particularly the structure constante of the refractive index C2n(h) and the outer scale L0(h). New techniques based on the moon limb observation for the monitoring of the C2n(h) and L0(h) profiles with high vertical resolution will be presented. A new monitor PBL (Profileur Bord Lunaire) for the extraction of the C2n(h) profile with high vertical resolution has been developed. This instrument uses an optical method based on observation of the moon limb with a DIMM configuration (Differential Image Motion Monitor). Indeed, in the PBL the lunar limb is observed through two sub-apertures of 6cm separated by a base of 30cm. The moon limb offers a continuum of stars at different angular separations allowing the scan the atmosphere with a very high resolution. The angular correlation along the lunar limb between of the differential distance between the two images of the lunar edge leads to the C2n(h) profile. The other parameters of turbulence are also accessible from this instrument as the profile of outer scale, the seeing and isoplanatic and isopistonic domains. The PBL succeeded to our first moon limb profiler MOSP (Monitor of Outer Scale Profile) which was developed mainly for outer scale profile extraction. Several campaigns have been carried out with MOSP particularly at Mauna Kea Observatory (Hawaii) and Cerro Paranal in Chile. The PBL instrument has been installed at Dome C in Antarctica since January 2011. In addition to this winterized PBL for Dome C, a second copy of this instrument has been developed for mid-latitude sites. A first campaign with this light version of PBL, was carried out at the South African Large Telescope (SALT) Observatory in August 2011.

Refined simulation tools for wide field AO systems (such as MOAO, MCOA or LTAO) on ELTS present new challenges. Increasing the number of degrees of freedom (scales as the square of the telescope diameter) makes the standard codes useless due to the huge number of operations to be performed at each step of the AO loop process. This computational burden requires new approaches in the computation of the DM voltages from WFS data. The classical matrix inversion and the matrix vector multiplication have to be replaced by a cleverer iterative resolution of the Least Square or Minimum Mean Square Error criterion (based on sparse matrices approaches). Moreover, for this new generation of AO systems, concepts themselves will become more complex: data fusion coming from multiple Laser and natural guide stars will have to be optimized, mirrors covering all the field of view associated to dedicated mirrors inside the scientific instrument itself will have to be coupled with split or integrated tomography schemes, differential pupil or/and field rotations will have to be considered, etc All these new entries should be carefully simulated, analyzed and quantified in terms of performance before any implementation in AO systems. In this paper we present a new E2E simulator, developed to deal with all these specific ELT challenges. It is based on an iterative resolution of the linear model with high number of degrees of freedom (using the sparse matrix) and includes new concepts of filtering and coupling between LGS and NGS to effectively manage modes such as tip / tilt and defocus in the entire process of tomographic reconstruction.

Extremely large telescopes will push the limits of astronomical observations to a level not achievable with the current generation of telescopes. It will be possible to observe to fainter magnitude limits and, with adaptive optics, with higher angular resolution due to the sizes of the primary mirrors. In addition, it is expected that ”quantitative techniques” such as astrometry and photometry will achieve levels of accuracy not possible today. This requires controlling the error sources affecting such measurements, for example distortions caused by all parts of the optics, to a higher level of accuracy for much larger components than on current telescopes. It may also be necessary to develop new calibration procedures, observing techniques and post-processing methods in the more challenging cases. In this paper, we give an overview of the challenges this presents for the design, construction and operation of ELTs, concentrating on the example of precision astrometry.

Adaptive Optics systems for instruments on the next generation of astronomical telescopes will be of a significantly higher order than those for existing systems. The requirements for processing power for real-time computers to control such systems will be substantial and may well not be met by the simple application of the next generation of CPU based computers. We present here an overview of the various designs for future real-time computer systems that are being investigated at Durham involving the acceleration (or replacement) of CPU systems by GPU and FPGA based hardware. We address the ongoing argument of which of these technologies should be employed for which applications. We present our plans for the testing of these technologies both in the laboratory and on-sky in the CANARY AO demonstrator at the 4m William Herschel Telescope, along with initial results and a design for the realtime control system for the proposed EAGLE instrument for the E-ELT.

For the ELTs the use of AO with multiple sodium Laser Guide Stars will be routine. We think it is important to study the LGS generation in order to optimize the LGS-AO systems. It is in this context that we are working on the understanding and optimization of the laser parameters. In this paper we report on a part of our LGS return flux studies, aimed at identifying the optimal laser formats for CW and pulsed lasers. We have done recently numerical simulations on the LGS return flux for different laser formats, solving the Bloch equations for the interaction of the mesospheric sodium atoms with the laser radiation. The simulations have been used for the design of the future ESO LGS facilities. However the simulations need to be validated. We report on the ESO Wendelstein transportable 20W LGS unit, recently built and commissioned to make systematic field studies on the LGS. The first experimental results on the LGS return flux obtained during the commissioning are reported.

We demonstrate experimentally that slicer based integral field spectrographs are an attractive choice for the next generation of exoplanet direct detection instruments. By propagating a single simulated speckle though a slicer based integral field spectrograph (IFS) and performing the post processing technique of spectral deconvolution we are able to achieve a speckle rejection factor of ~600 in broadband images (and ~100 in individual wavelength channels) with contrasts only appearing to be limited by calibration errors in the IFS datacube. This is over an order of magnitude improvement on the current state-of-the-art and well within the requirements of EPICS (Exo Planet Imaging Camera and Spectrograph for the E-ELT) for post coronagraphic speckle rejection thus proving that slicers will not impose a limit on the achievable contrast. When using prior knowledge of the diffraction-limited size of real objects we further improve the speckle rejection factor such that it exceeds 10e3.

MAORY is the multi-conjugate adaptive optics module for the future European Extremely Large Telescope. This paper describes the design and estimated performance of the module after the phase-A study; in particular two optical design options of the MAORY post-focal relay are discussed.

Presently, dedicated instruments at large telescopes (SPHERE for the VLT, GPI for Gemini) are about to discover and explore self-luminous giant planets by direct imaging and spectroscopy. The next generation of 30m-40m ground-based telescopes, the Extremely Large Telescopes (ELTs), have the potential to dramatically enlarge the discovery space towards older giant planets seen in reflected light and ultimately even a small number of rocky planets. EPICS is a proposed instrument for the European ELT, dedicated to the detection and characterization of Exoplanets by direct imaging, spectroscopy and polarimetry. ESO completed a phase-A study for EPICS with a large European consortium which - by simulations and demonstration experiments - investigated state-of-the-art diffraction and speckle suppression techniques to deliver highest contrasts. The paper presents the instrument concept and analysis as well as its main innovations and science capabilities. EPICS is capable of discovering hundreds of giant planets, and dozens of lower mass planets down to the rocky planets domain. © 2010 Copyright SPIE - The International Society for Optical Engineering.

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 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. INO is responsible for the Raven calibration unit design, fabrication and test. This sub-system consists in a telescope and turbulence simulator that will allow aligning Raven’s components during its integration, testing its AO performances in the laboratory and at the telescope, and calibrating the AO system by building the interaction matrix and measuring the non-common path aberrations (NCPA). This sub-system is described in this paper. Its main challenges are to ensure that all the focal plane and pupil plane requirements will be met when considering manufacturing and alignment errors over its full waveband and across its field-of-view. This system is to be designed, fabricated and testes in seven months.

GeMS (the Gemini MCAO System) is a facility instrument for the Gemini-South telescope. The system includes five laser guide stars, three natural guide stars, three deformable mirrors optically conjugated at 0, 4.5 and 9km and one tip-tilt mirror. Some of its unique features include an embedded Cn2 SLODAR profiler which is described in this paper. The Cn2 profile is reconstructed from the slopes seen by the 5 high order WFS, each one pointing in a laser guide star direction. Residuals from the 16x16 subapertures WFSs and DM commands are used to obtain pseudo-open loop data for SLODAR, allowing us to reconstruct up to 16 layers. The paper describes the results obtained from different validation steps followed during the development of the technique, namely: numerical simulations, artificially generated turbulence via DMs excitation and the use of on-sky data obtained from different commissioning nights. We also present results from a wind profiler that runs in parallel to SLODAR and finally compare the results to those from a nearby MASS/DIMM instrument.

The near infrared interferometer LINC-NIRVANA combines the beams coming from the two primary mirrors of the Large Binocular Telescope to increase the resolution of the science camera image. LINC-NIRVANA is using layer-oriented multi-conjugate adaptive optics (MCAO) to reduce the influence of the atmospheric turbulence. The deformable mirrors of the MCAO systems are conjugated to the ground layer and a second layer in the upper atmosphere, respectively. Ground layer wavefront sensors and high layer wavefront sensors measure the wavefront in these two layers. Due to geometrical constraints unique to this type of instrument, it is not possible to provide a single derotator at the entrance of each incoming beam. Due to that fact, field derotation has to be applied for each wavefront sensor and for the science detector separately. The fields of the high layer wavefront sensors are derotated by the use of K-Mirrors, whereas the ground layer wavefront sensors and the science detector rotate themselves to compensate field rotation. All derotators are driven by common software that provides functionality to generate, execute, and maniulate a trajectory. The trajectory handling for these field derotators will be discussed in this paper. We introduce an algorithm that translates a requested trajectory into motor controller commands in due consideration of the required accuracy. Finally, we present the achieved positioning accuracy of the translated trajectory and compare that result with the traced position path of the derotator.

ESO has developed a concept for a compact laser guide star unit for use in future Adaptive Optics (AO) systems. A small powerful laser is combined with a telescope that launches the beam, creating a single modular unit that can be mounted directly on a large telescope. This approach solves several of the stability problems experienced with a number of first generation laser guide star systems around the world. Four of these compact laser guide stars will be used for the new VLT 4LGSF Adaptive Optics Facility (AOF), to be installed on UT4 in Paranal. The design is passively athermalized over a large temperature range as well as under the influence of thermal gradients. TNO has developed the laser launch telescopes and successfully demonstrated its performance under operational conditions. The technology will also serve as a testbed ahead of the construction of the future European Extremely Large Telescope, which will also have multiple laser guide star units.

Our team has started the development of a code dedicated to GPUs for the simulation of adaptive optics systems at the E-ELT scale. It uses the CUDA toolkit and an original binding to Yorick (an open source interpreted language) to provide the user with a comprehensive interface. In this paper we present the first performance analysis of our simulation code, showing its ability to provide Shack-Hartmann (SH) images and measurements at the kHz scale for VLT-sized AO system and in quasi-real-time (up to 70 Hz) for ELT-sized systems on a single top-end GPU. The simulation code includes multiple layers atmospheric turbulence generation, ray tracing through these layers, image formation at the focal plane of every sub-aperture of a SH sensor using either natural or laser guide stars and centroiding on these images using various algorithms. Turbulence is generated on-the-fly giving the ability to simulate hours of observations without the need of loading extremely large phase screens in the global memory. Because of its performance this code additionally provides the unique ability to test real-time controllers for future AO systems under nominal conditions.

We present our design of ESO E-ELT M4 deformable mirror and GMT Adaptive Secondary Mirrors unit. Both systems are based on our consolidated design of large deformable mirrors for 8-m class telescopes, successfully implemented on MMT and LBT and currently in advanced construction and testing phase for VLT and Magellan telescopes respectively. We describe the main features of the technology adopted: thin Zerodur mirror shell with contactless voice coil motors, co-located capacitive sensors to close a local position loop at each actuator, centralized control by force feedforward, embedded real time control and communication electronics. We then highlight how the same concept has been scaled up on the E-ELT M4AU and the GMT-ASM cases, adapting the technology to deal with thousands of actuators, while maintaining its intrinsic advantages: tolerance to actuators' failures, mechanical de-coupling and relaxed tolerances between correcting mirror and reference structure, large stroke, hysteresis-free behavior. For the next generation systems, we report the predicted performances based on the actual results attained on our 1-m class DMs currently in use: the LBT adaptive secondary for the GMT-ASM and the 330 actuators Demonstration Prototype for the E-ELT M4AU.

Multi-Object Adaptive Optics (MOAO) is an adaptive optics technique in development for Extremely Large Telescopes and will allow simultaneous observation of up to 20 targets in a several arc-minute field-of- view. Raven is an MOAO pathfinder developed by the Adaptive Optics Laboratory of the University of Victoria, in collaboration with the Herzberg Institute of Astrophysics and the Subaru Telescope. Its goal is to demonstrate that MOAO technical challenges such as open-loop control and calibration are achievable on-sky and also to deliver science results. The open-loop (OL) approach makes the need for calibration even more crucial. We will present the specific calibration procedures of Raven in two steps. The first one is to find the command matrices between the three open-loop wavefront sensors (WFS) with the two deformable mirrors (DM) used to correct the wavefront on the science paths. Because of the OL, we add components such as a calibration-DM in front of the whole system and also close-loop WFS behind each DM. We register the DM with the CL-WFS and then the calibration-DM with all of the five WFS and then compute the command matrices. The goal of the second step is to remove the field-dependent non-common path aberrations (NCPAs). That task is common in AO systems but presents a bigger challenge in this case because of the open-loop control and also the moving pick-off arms.

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 layeroriented, 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 paper, we provide an update on the integration and testing of the instrument, and attempt to foresee and forestall future lessons learned.

Adaptive Optics (AO) systems of the Extremely Large Telescopes (ELT) will incorporate deformable mirrors with an order of magnitude larger number of piezoelectric actuators than the AO systems currently deployed. Simply scaling up the drive electronics offered commercially would substantially drive up the AO cost, pose unacceptably high demands for the supply power, and occupy large volume. We are progressing on the design of a compact high voltage amplifier with the goal to have a Deformable Mirror (DM) drive density of 1200 channels per 6U VME crate. Amplifiers will be driven by multichannel D/A converters, consume no more than 0.5 W power each, be slew rate limited in hardware, and be short-circuit protected. In addition, the cost per amplifier is expected to be drastically lower compared to the integrated circuit amplifier currently used in smaller scale AO systems. Several suitable circuits using inexpensive components have been conceived and investigated by computer simulation and built. In this paper we present experimental results of prototype circuits exposed to both normal operating conditions and foreseeable fault conditions. The performance is evaluated against the AO requirements for the output range and bandwidth as well as the DM actuator operational safety requirements.

The correct calibration of the interaction matrix affects the performance of an adaptive optics system. In the case of high-order systems, when the number of mirror modes is worth a few thousands, the calibration strategy is critical to reach the maximum interaction matrix quality in the minimum time. This is all the more true for the E-ELT, for which on sky calibration procedures have to be considered. Here, we first build a tractable interaction matrix quality criterion. We then propose the Slope-Oriented Hadamard scheme which optimizes this quality criterion.We demonstrate that for a given level of quality, the calibration time needed using the Slope-Oriented Hadamard method is ten times less than with a classical Hadamard scheme. These analytical and simulation results are confirmed experimentally on the SPHERE XAO system (SAXO).

Micro-electro mechanical devices (MEMS) deformable mirrors offer a compact and affordable path to complex next generation AO instruments on large telescopes. In this presentation we discuss the motivators and challenges of next generation AO and describe our plans and experimental progress on two MEMS-based AO systems: the high-contrast Gemini Planet Imager, the Shan eAO laser guidestar system, and the proposed Keck Next Generation AO system.

While a large visible fast low-noise detector for a Shack-Hartmann wavefront sensor (SH WFS) for an ELT does not exist yet, the current CCD technology pushed to its limits already provides several solutions for the ELT AO detector requirements. One of these devices is the new WFS pnCCD camera of ARGOS, the Ground-Layer Adaptive Optics system (GLAO) for LUCI at LBT. Indeed, with its 264x264 pixels, 48 micro m pixel size and 1kHz frame rate, this camera provides a technological solution to different needs of the AO systems for ELTs, such as "first-light" low-order SH but as well possibly higher order sensing using pyramid WFS. In this contribution, we present the newly developed WFS pnCCD camera of ARGOS and how it fulfills future detector needs of AO on ELTs.

Conceptual and feasibility studies of wide field AO systems for Subaru Telescope has been started as a next generation AO system. Since optical wide field imager, named Hyper Supreme Camera, and multi object fiber-fed spectrograph, named Prime Focus Spectrograph, are currently under developing for a primary focus of Subaru Telescope, a wide field imager and spectrograph at near infrared wavelength range with adaptive optics at Cassegrain or Nasmyth foci must be a complemental instrument in the next future. In this paper, preliminary performance simulation studies of GLAO and MOAO and science case study in imaging and spectrograph are introduced. A GLAO simulation tells us that stellar image size is almost uniform up to 20 arcmin FOV. We found that a number of tip-tilt guide star and its constellation is closely related to the performance of MOAO. Imaging sensitivity gain is expected about 0.5 magnitude for the point source and 0.3 to 0.4 magnitude for compact galaxies, whose effective radius is smaller than 3 kpcs at the redshift around 2. On the other hand, the analysis of a spectroscopy observation to investigate kinematics of high redshift galaxies seems to be not easy using GLAO.