This PDF file contains the front matter associated with SPIE Proceedings Volume 7736, including the Title Page, Copyright information, Table of Contents, and the Conference Committee listing.

The new generation of extremely large telescopes (ELTs) will have key advantages over today's 8-10m telescopes. They will collect more light due to their larger area: light-gathering power scales as the telescope diameter D², so gains of a factor of ~10 or more are expected. Further, with adaptive optics performing at close to the diffraction limit, ELTs will have much higher point-source sensitivity. This is because for observations limited by background light from the sky, there will be less background included within a diffraction-limited area. Point-source sensitivity will improve at least as fast as D⁴, permitting gains of a factor of 70 - 100. We describe a few of the areas of astronomical science which stand to benefit from these huge performance improvements: 1) Direct imaging and spectroscopy of giant extrasolar planets, and of protoplanetary disks. 2) Resolved stellar populations and in particular the kinematics of stars close to the black hole at the Galactic Center, and 3) Properties of galaxies at redshifts from 1.5 to 7, to shed new light on the processes of galaxy assembly and evolution. These and other new science capabilities will enable ELTs to produce dramatic advances in astrophysical understanding.

Adaptive optics (AO) is essential for many elements of the science case for the Thirty Meter Telescope (TMT). The initial requirements for the observatory's facility AO system include diffraction-limited performance in the near IR, with 50 per cent sky coverage at the galactic pole. Point spread function uniformity and stability over a 30 arc sec field-ofview are also required for precision photometry and astrometry. These capabilities will be achieved via an order 60×60 multi-conjugate AO system (NFIRAOS) with two deformable mirrors, six laser guide star wavefront sensors, and three low-order, IR, natural guide star wavefront sensors within each client instrument. The associated laser guide star facility (LGSF) will employ 150W of laser power at a wavelength of 589 nm to generate the six laser guide stars. We provide an update on the progress in designing, modeling, and validating these systems and their components over the last two years. This includes work on the layouts and detailed designs of NFIRAOS and the LGSF; fabrication and test of a full-scale prototype tip/tilt stage (TTS); Conceptual Designs Studies for the real time controller (RTC) hardware and algorithms; fabrication and test of the detectors for the laser- and natural-guide star wavefront sensors; AO system modeling and performance optimization; lab tests of wavefront sensing algorithms for use with elongated laser guide stars; and high resolution LIDAR measurements of the mesospheric sodium layer. Further details may be found in specific papers on each of these topics.

The Magellan Clay telescope is a 6.5m Gregorian telescope located in Chile at Las Campanas Observatory. The Gregorian design allows for an adaptive secondary mirror that can be tested off-sky in a straightforward manner. We have fabricated a 85 cm diameter aspheric adaptive secondary with our subcontractors and partners, the ASM passed acceptance tests in July 2010. This secondary has 585 actuators with <1 msec response times (0.7 ms typically). This adaptive secondary will allow low emissivity AO science. We will achieve very high Strehls (~98%) in the Mid-IR (3-26 microns) with the BLINC/MIRAC4 Mid-IR science camera. This will allow the first "super-resolution" and nulling Mid-IR studies of dusty southern objects. We will employ a high order (585 mode) pyramid wavefront sensor similar to that now successfully used at the Large Binocular Telescope. The relatively high actuator count will allow modest Strehls to be obtained in the visible (0.63-1.05 μm). Moderate (~20%) Strehls have already been obtained at 0.8 μm at the LBT with the same powerful combination of a next generation ASM and Pyramid WFS as we are providing for Magellan. Our visible light AO (VisAO) science camera is fed by an advanced triplet ADC and is piggy-backed on the WFS optical board. We have designed an additional "clean-up" very fast (2 kHz) tilt stabilization system for VisAO. Also a high-speed shutter will be used to block periods of poor correction. The VisAO facility can be reconfigured to feed an optical IFU spectrograph with 20 mas spaxels. The entire system passed CDR in June 2009, and is now finished the fabrication phase and is entering the integration phase. The system science and performance requirements, and an overview the design, interface and schedule for the Magellan AO system are presented here.

GeMS (the Gemini Multi-conjugated adaptive optics System) is a facility instrument for the Gemini-South telescope. It will deliver a uniform, diffraction-limited image quality at near-infrared (NIR) wavelengths over an extended FoV or more than 1 arcmin across. GeMS is a unique and challenging project from the technological point of view and because of its control complexity. 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. After 10 years since the beginning of the project, GeMS is finally reaching a state in which all the subsystems have been received, integrated and, in the large part, tested. In this paper, we report on the progress and current status of the different sub-systems with a particular emphasis on the calibrations, control and optimization of the AO bench.

The testbed of the MCAO for the new 1.5 meter solar telescope GREGOR is now operational. Most of the components will be moved to the telescope after commissioning. The testbed features 4 adaptive mirrors (1 tiptilt, and 3 DMs), and two Hartmann-Shack sensor units for wavefront tomography in a guide-region oriented approach. First system characteristics gained from setting up operation of the testbed are presented. We also comment on the effect of high-altitude deformable mirrors on subaperture alignment, and misregistration. We conclude that on-axis wavefront sensors should not be located behind high-altitude deformable mirrors. Furthermore, we present a general opto-geometric characteristic of micro-lens arrays needed for a Hartmann-Shack sensor which shall be used for extended fields of view - be it solar surface or laser guide stars, for example. This characteristic can be useful to have custom-made arrays manufactured for reasonable prices.

The high order adaptive optics (HOAO) system is the centerpiece of the ATST wavefront correction system. The ATST wavefront correction system is required to achieve a Strehl of S = 0.6 or better at visible wavelength. The system design closely follows the successful HOAO implementation at the Dunn Solar Telescope and is based on the correlating Shack-Hartmann wavefront sensor. In addition to HOAO the ATST will utilize wavefront sensors to implement active optics (aO) and Quasi Static Alignment (QSA) of the telescope optics, which includes several off-axis elements. Provisions for implementation of Multi-conjugate adaptive optics have been made with the design of the optical path that feeds the instrumentation at the coudé station. We will give an overview of the design of individual subsystems of the ATST wavefront correction system and describe some of the unique features of the ATST wavefront correction system, such as the need for thermally controlled corrective elements.

In this paper we present the laboratory characterization and performance evaluation of the First Light Adaptive Optics (FLAO) the Natural Guide Star adaptive optics system for the Large Binocular Telescope (LBT). The system uses an adaptive secondary mirror with 672 actuators and a pyramid wavefront sensor with adjustable sampling of the telescope pupil from 30×30 down to 4×4 subapertures. The system was fully assembled in the Arcetri Observatory laboratories, passing the acceptance test in December 2009. The performance measured during the test were closed to goal specifications for all star magnitudes. In particular FLAO obtained 83% Strehl Ratio (SR) in the bright end (8.5 magnitudes star in R band) using H band filter and correcting 495 modes with 30×30 subapertures sampling. In the faint end (16.4 magnitude) a 5.0% SR correcting 36 modes with 7×7 subapertures was measured. The seeing conditions for these tests were 0.8" (r0 = 0.14m @ 550 nm) and an average wind speed of 15m/s. The results at other seeing conditions up to 1.5" are also presented. The system has been shipped to the LBT site, and the commissioning is taking place since March to December 2010. A few on sky results are presented.

Ground-layer Adaptive Optics offers a unique approach to enhancing the power of large telescopes to explore a wide range of astrophysical phenomena. By accessing wide fields of view with image concentrations that are significantly improved over natural seeing, ground-layer AO systems can probe stellar populations in crowded and confused regions of the Milky Way and nearby galaxies, probe the internal dynamics of large samples of galaxies in the distant universe and provide a cost effective path towards highly multiplexed observations of large samples. The improved image concentration over large fields of view offered by ground-layer AO will allow significant gains in sensitivity for multiobject spectrographs operating in the near-IR. This will lead to improved understanding of the formation of the first galaxies and stars as well as the evolution of massive galaxies when the Universe was a few billion years old. Groundlayer AO systems have the potential to eliminate poor seeing from most astronomical sites and to improve the productivity of large and extremely large telescopes.

NFIRAOS, the TMT Observatory's initial facility AO system is a multi-conjugate AO system feeding science light from 0.8 to 2.5 microns wavelength to several near-IR client instruments. NFIRAOS has two deformable mirrors optically conjugated to 0 and 11.2 km, and will correct atmospheric turbulence with 50 per cent sky coverage at the galactic pole. An important requirement is to have very low background: the plan is to cool the optics; and one DM is on a tip/tilt stage to reduce surface count. NFIRAOS' real time control uses multiple sodium laser wavefront sensors and up to three IR natural guide star tip/tilt and/or tip/tilt/focus sensors located within each client instrument. Extremely large telescopes are sensitive to errors due to the variability of the sodium layer. To reduce this sensitivity, NFIRAOS uses innovative algorithms coupled with Truth wavefront sensors to monitor a natural star at low bandwidth. It also includes an IR acquisition camera, and a high speed NGS WFS for operation without lasers. For calibration, NFIRAOS includes simulators of both natural stars at infinity and laser guide stars at varying range distance. Because astrometry is an important science programme for NFIRAOS, there is a precision pinhole mask deployable at the input focal plane. This mask is illuminated by a science wavelength and flat-field calibrator that shines light into NFIRAOS' entrance window. We report on recent effort especially including trade studies to reduce field distortion in the science path and to reduce cost and complexity.

The design of the adaptive optics (AO) system for the GMT is currently being developed. The baseline system is planned around a segmented adaptive secondary mirror (ASM), with elements similar in size to current ASM's for 8 m telescopes. A facility wavefront sensing system is planned to provide AO correction at several science instrument ports. The AO system will contain a subsystem dedicated to controlling the relative phases between the seven segments of the GMT aperture. The anticipated modes include natural guide star, laser tomography, and ground layer adaptive optics. A cooled optical relay is described to provide baffling and reimaging of the focal plane to the various science ports. The laser projection system will use six beacons on an adjustable radius to support both diffraction-limited and ground layer correction modes. Modeling work, as well as science instrument design development will be integrated with this design effort to develop a concept that provides efficient diffraction-limited performance and seeing-improved capabilities for the GMT.

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.

ARGOS is the Laser Guide Star adaptive optics system for the Large Binocular Telescope. Aiming for a wide field adaptive optics correction, ARGOS will equip both sides of LBT with a multi laser beacon system and corresponding wavefront sensors, driving LBT's adaptive secondary mirrors. Utilizing high power pulsed green lasers the artificial beacons are generated via Rayleigh scattering in earth's atmosphere. ARGOS will project a set of three guide stars above each of LBT's mirrors in a wide constellation. The returning scattered light, sensitive particular to the turbulence close to ground, is detected in a gated wavefront sensor system. Measuring and correcting the ground layers of the optical distortions enables ARGOS to achieve a correction over a very wide field of view. Taking advantage of this wide field correction, the science that can be done with the multi object spectrographs LUCIFER will be boosted by higher spatial resolution and strongly enhanced flux for spectroscopy. Apart from the wide field correction ARGOS delivers in its ground layer mode, we foresee a diffraction limited operation with a hybrid Sodium laser Rayleigh beacon combination.

The direct imaging of exoplanet is a challenging goal of todays astronomy. The light transmitted by exoplanet atmosphere is of a great interest as it may witness for life sign. SPHERE is a second generation instrument for the VLT, dedicated to exoplanet imaging, detection, and characterisation. SPHERE is a global project of an European consortium of 11 institutes from 5 countries. We present here the state of the art of the AIT of the Adaptive Optics part of the instrument. In addition we present fine calibration procedures dedicated to eXtreme Adaptive Optics systems. First we emphasized on vibration and turbulence identification for optimization of the control law. Then, we describe a procedure able to measure and compensate for NCPA with a coronagraphic system.

Laser beams projected from the ground to form laser guide stars (LGS) experience scattering and absorption that reduce their intensity as they propagate through the atmosphere. Some fraction of the scattered light will be collected by the other LGS wavefront sensors and causes additional background in parts of the pupil. This cross-talk is referred to as the fratricide effect. In this paper we quantify the magnitude of four different sources of scattering/absorption and back scattering, and evaluate their impact on performance with various zenith angles and turbulence profiles for the Thirty Meter Telescope (TMT) MCAO system, NFIRAOS. The resulting wavefront error is on the order of 5 to 20 nm RMS, provided that the mean background from the fratricide can be calibrated and subtracted with an accuracy of 80%. We have also found that the impact of fratricide is a weak function of LGS asterism radius.

The use of software based simulation packages is essential for the design of adaptive optics systems on next generation ELT scale telescopes. We present Monte-Carlo AO simulation results for an E-ELT multi-IFU spectrograph instrument comprising multiple laser and natural guide stars with wavefront correction along multiple lines of sight. We discuss the techniques used to perform these simulations. Considerations are also given to compressed reconstructor representations which can greatly simplify the design of real-time control systems. We also discuss work on the use of GPUs for AO simulation.

We investigate in this article tomographic control using both Laser and Natural Guide Stars (LGS and NGS) in the particular framework of the European Extremely Large Telescope (E-ELT) Wide Field Adaptive Optics (WFAO) modules design. A similar global control strategy has been indeed derived for both the Laser Tomographic Adaptive Optics (LTAO) and Multi-Conjugate Adaptive Optics (MCAO) modules of the E-ELT, due to similar constraints. This control strategy leads in both cases to a split control of low order modes measured thanks to NGS and high order modes measured thanks to LGS. We investigate here this split tomographic control, compared to an optimal coupled solution. To support our analysis, a dedicated simulation code has been developed. Indeed, due to the huge complexity of the EELT, fast simulation tools must be considered to explore quickly the tomographic issues. We describe our control strategy which has lead to considering split tomographic control. First results on Tomography for E-ELT WFAO systems are then presented and discussed.

WFAO systems are in their design phase for the ELTs. MCAO (MAORY), LTAO (ATLAS) and MOAO (EAGLE) approaches have been analyzed for the E-ELT. All these approaches require a precise tomographic reconstruction of the turbulent volume. In that frame, Cn² profiles come up at two levels: the input "true" profile, and the prior profile used as a regularization in the tomographic reconstruction. The impacts of the structure and the complexity of the Cn² profile on the residual error after tomographic reconstruction are analyzed and discussed. We show that isoplanatic angle is not sufficient to characterize profiles in WFAO. We highlight the importance of a well sampled Cn² input profile and prior profile to be considered in the tomographic reconstructor.

We report on the preliminary design of W.M. Keck Observatory's (WMKO's) next-generation adaptive optics (NGAO) facility. This facility is designed to address key science questions including understanding the formation and evolution of today's galaxies, measuring dark matter in our galaxy and beyond, testing the theory of general relativity in the Galactic Center, understanding the formation of planetary systems around nearby stars, and exploring the origins of our own solar system. The requirements derived from these science questions have resulted in NGAO being designed to have near diffraction-limited performance in the near-IR (K-Strehl ~ 80%) over narrow fields (< 30" diameter) with modest correction down to ~ 700 nm, high sky coverage, improved sensitivity and contrast and improved photometric and astrometric accuracy. The resultant key design features include multi-laser tomography to measure the wavefront and correct for the cone effect, open loop AO-corrected near-IR tip-tilt sensors with MEMS deformable mirrors (DMs) for high sky coverage, a high order MEMS DM for the correction of atmospheric and telescope static errors to support high Strehls and high contrast companion sensitivity, point spread function (PSF) calibration to benefit quantitative astronomy, a cooled science path to reduce thermal background, and a high-efficiency science instrument providing imaging and integral field spectroscopy.

The ESO Adaptive Optics Facility (AOF) consists in an evolution of one of the ESO VLT unit telescopes to a laser driven adaptive telescope with a deformable mirror in its optical train, in this case the secondary 1.1m mirror, and four Laser Guide Stars (LGSs). This evolution implements many challenging technologies like the Deformable Secondary Mirror (DSM) including a thin shell mirror (1.1 m diameter and 2mm thin), the high power Na lasers (20W), the low Read-Out Noise (RON) WaveFront Sensor (WFS) camera (< 1e-) and SPARTA the new generation of Real Time Computers (RTC) for adaptive control. It also faces many problematic similar to any Extremely Large Telescope (ELT) and as such, will validate many technologies and solutions needed for the European ELT (E-ELT) 42m telescope. The AOF will offer a very large (7 arcmin) Field Of View (FOV) GLAO correction in J, H and K bands (GRAAL+Hawk-I), a visible integral field spectrograph with a 1 arcmin GLAO corrected FOV (GALACSI-MUSE WFM) and finally a LTAO 7.5" FOV (GALACSI-MUSE NFM). Most systems of the AOF have completed final design and are in manufacturing phase. Specific activities are linked to the modification of the 8m telescope in order to accommodate the new DSM and the 4 LGS Units assembled on its Center-Piece. A one year test period in Europe is planned to test and validate all modes and their performance followed by a commissioning phase in Paranal scheduled for 2014.

The M5 Field stabilization Unit (M5FU) for European Extremely Large Telescope (E-ELT) is a fast correcting optical system that shall provide tip-tilt corrections for the telescope dynamic pointing errors and the effect of atmospheric tiptilt and wind disturbances. A M5FU scale 1 demonstrator (M5FU1D) is being built to assess the feasibility of the key elements (actuators, sensors, mirror, mirror interfaces) and the real-time control algorithm. The strict constraints (e.g. tip-tilt control frequency range 100Hz, 3m ellipse mirror size, mirror first Eigen frequency 300Hz, maximum tip/tilt range ± 30 arcsec, maximum tiptilt error < 40 marcsec) have been a big challenge for developing the M5FU Conceptual Design and its scale 1 demonstrator. The paper summarises the proposed design for the final unit and demonstrator and the measured performances compared to the applicable specifications.

The current status of commissioning and recent results in performance of Subaru laser guide star adaptive optics system is presented. After the first light using natural guide stars with limited configuration of the system in October 2006, we concentrated to complete a final configuration for a natural guide star to serve AO188 to an open use observation. On sky test with full configurations using natural guide star started in August 2008, and opened to a public one month later. We continuously achieved around 0.6 to 0.7 of Strehl ratio at K band using a bright guide star around 9th to 10th magnitude in R band. We found an unexpectedly large wavefront error in our laser launching telescope. The modification to fix this large wavefront error was made and we resumed the characterization of a laser guide star in February 2009. Finally we obtained a round-shaped laser guide star, whose image size is about 1.2 to 1.6 arcsec under the typical seeing condition. We are in the final phase of commissioning. A diffraction limited image by our AO system using a laser guide star will be obtained in the end of 2010. An open use observation with laser guide star system will start in the middle of 2011.

The Laser Adaptive Optics system of the 6.5 m MMT telescope has now been commissioned with Ground Layer Adaptive Optics operations as a tool for astronomical science. In this mode the wavefronts sampled by each of five laser beacons are averaged, leading to an estimate of the aberration in the ground layer. The ground layer is then compensated by the deformable secondary mirror at 400 Hz. Image quality of 0.2-0.3 arc sec is delivered in the near infrared bands from 1.2-2.5 μm over a field of view of 2 arc minutes. Tomographic wavefront sensing tests in May 2010 produced open loop data necessary to streamline the software to generate a Laser Tomography Adaptive Optics (LTAO) reconstructor. In addition, we present the work being done to achieve optimal control PID wavefront control and thus increase the disturbance rejection frequency response for the system. Finally, we briefly describe plans to mount the ARIES near infrared imager and echelle spectrograph, which will support the 2 arc min ground-layer corrected field and will exploit the diffraction limit anticipated with LTAO.

The CANARY on-sky MOAO demonstrator is being integrated in the laboratory and a status update about its various components is presented here. We also discuss the alignment and calibration procedures used to improve system performance and overall stability. CANARY will be commissioned at the William Herschel Telescope at the end of September 2010.

The Multi-conjugate Adaptive Optics RelaY (MAORY) for the European Extremely Large Telescope (E-ELT) provides a corrected field of view of up to 2 arcmin diameter over the wavelength range 0.8-2.4 μm. It is expected to achieve a correction of high quality and uniformity with high sky coverage: with a seeing of 0.8 arcsec in the visible, the expected Strehl Ratio averaged over a 1 arcmin field is approximately 50% at 2.16 μm wavelength over 50% of the sky at the Galactic Pole. Wavefront correction is obtained by means of the E-ELT adaptive mirrors M4/M5 and of two post-focal deformable mirrors conjugated at 4km and 12.7km from the telescope pupil. Wavefront sensing is performed by 6 Sodium laser guide stars and by 3 natural guide stars, used to measure atmospheric and windshake tilt and to provide a reference for the focus and for the low-order aberrations induced by the Sodium layer. MAORY is located on the E-ELT Nasmyth platform and has a gravity invariant port, feeding the high angular resolution camera MICADO, and a lateral port for a detached instrument as the infrared spectrograph SIMPLE.

EAGLE is the multi-object spatially-resolved near-IR spectrograph instrument concept for the E-ELT, relying on a distributed Adaptive Optics, so-called Multi Object Adaptive Optics. This paper presents the results of a phase A study. Using 84×84 actuator deformable mirrors, the performed analysis demonstrates that 6 laser guide stars (on an outer ring of 7.2' diameter) and up to 5 natural guide stars of magnitude R < 17, picked-up in a 7.3' diameter patrol field of view, allow us to obtain an overall performance in terms of Ensquared Energy of 35% in a 75×75mas² resolution element at H band whatever the target direction in the centred 5' science field for median seeing conditions. In terms of sky coverage, the probability to find the 5 natural guide stars is close to 90% at galactic latitudes |b| ~ 60 deg. Several MOAO demonstration activities are also on-going.

In the context of instrumentation for Extremely Large Telescopes (ELTs), an Integral Field Spectrographs (IFSs), fed with a Multi-Object Adaptive Optics (MOAO) system, has many scientific and technical advantages. Integrated with an ELT, a MOAO system will allow the simultaneous observation of up to 20 targets in a several arc-minute field-of-view, each target being viewed with unprecedented sensitivity and resolution. However, before building a MOAO instrument for an ELT, several critical issues, such as open-loop control and calibration, must be solved. The Adaptive Optics Laboratory of the University of Victoria, in collaboration with the Herzberg Institute of Astrophysics, the Subaru telescope and two industrial partners, is starting the construction of a MOAO pathfinder, called Raven. The goal of Raven is two-fold: first, Raven has to demonstrate that MOAO technical challenges can be solved and implemented reliably for routine on-sky observations. Secondly, Raven must demonstrate that reliable science can be delivered with multiplexed AO systems. In order to achieve these goals, the Raven science channels will be coupled to the Subaru's spectrograph (IRCS) on the infrared Nasmyth platform. This paper will present the status of the project, including the conceptual instrument design and a discussion of the science program.

A consortium of more than 20 European solar physics institution from 15 different countries is conducting a design study for a 4 m class solar telescope which shall be situated at the Canary Islands. In this paper we introduce the AO and MCAO design concept for EST. A ground layer deformable mirror is combined with an arrangement of four deformable layer mirrors. A combination of Shack-Hartmann wave front sensors with wide and narrow fields of view is used to control the system and to achieve a corrected field of view of one arcmin.

We extend previous sodium LGS models by integrating the return flux across the mesosphere, taking into account variable mesospheric gas density, temperature, and local sodium density. This method allows us to produce accurate predictions of the actual return flux on the ground, relevant for determining the performance of adaptive-opticsassisted instruments. We find that the flux distribution across the sky depends strongly on geographic location and laser parameters. Almost independent of location, future sodium LGS will be about three times brighter at zenith than at the observing horizon.

This paper describes the modeling efforts undertaken in the past couple of years to derive wavefront error (WFE) performance estimates for the Narrow Field Infrared Adaptive Optics System (NFIRAOS), which is the facility laser guide star (LGS) dual-conjugate adaptive optics (AO) system for the Thirty Meter Telescope (TMT). The estimates describe the expected performance of NFIRAOS as a function of seeing on Mauna Kea, zenith angle, and galactic latitude (GL). They have been developed through a combination of integrated AO simulations, side analyses, allocations, lab and lidar experiments.

A challenge of adaptive optics (AO) on Extremely Large Telescopes (ELTs) is to overcome the difficulty of solving a huge number of equations in real time, especially when atmospheric tomography is involved. This is particularly the case for multi-conjugate or multi-objects AO systems. In addition, the quality of the wavefront estimation is crucial to optimize the performances of the future systems in a situation where measurements are missing and noises are correlated. The Fractal Iterative Method has been introduced as a fast iterative algorithm for minimum variance wavefront reconstruction and control on ELTs. This method has been successfully tested on Classical Single Conjugate AO systems on Octopus numerical simulator at ESO. But the minimum variance approach is expected to be mostly useful with atmospheric tomography. We present the first results obtained with FrIM in the context of atmospheric tomography. We recall the principle of the algorithm and we summarize the formalism used for modeling the measurements obtained from laser guide stars that entail spot elongation and tip/tilt indetermination, mixed with low order measurements from natural guide stars. We show the respective effects of tip/tilt indetermination, spot elongation, unseen modes on various configurations, as well as the usefulness of priors and correct noise models in the reconstruction. This analysis is essential for balancing the various errors that combine in a quite complex way and to optimize the configuration of the future AO systems for specific science cases and instrument requirements.

Tomographic AO (or Wide Field AO) systems use LGS to build a 3D model of turbulence, but rely on NGS for low order sensing. .To preserve reasonable sky coverage, each photon coming from the NGS to sense Tip Tilt has to be optimally exploited. That means a smart control law, a low detection noise, a concentration of the photons onto a small patch and a wave front sensor concept with favorable noise propagation. In this paper, we describe the system choices that were made during the E-ELT laser tomographic system ATLAS phase A study, in order to get a sky coverage as close as possible to 100%. A correct estimation of the sky coverage is therefore a key issue. We have developped a sky coverage estimation strategy based on a Besan¸con model starfield generation, a star(s) selection tool, and a careful estimation of the residual anisoplanatism (after reconstruction process between the NGSs), noise and temporal contributors. We describe the details of the procedure, and derive the ATLAS expected performance.

For the first time, sub-electron read noise has been achieved with a camera suitable for astronomical wavefront-sensing (WFS) applications. The OCam system has demonstrated this performance at 1300 Hz frame rate and with 240×240-pixel frame rate. ESO and JRA2 OPTICON² have jointly funded e2v technologies to develop a custom CCD for Adaptive Optics (AO) wavefront sensing applications. The device, called CCD220, is a compact Peltier-cooled 240×240 pixel frame-transfer 8-output back-illuminated sensor using the EMCCD technology. This paper demonstrates sub-electron read noise at frame rates from 25 Hz to 1300 Hz and dark current lower than 0.01 e-/pixel/frame. It reports on the comprehensive, quantitative performance characterization of OCam and the CCD220 such as readout noise, dark current, multiplication gain, quantum efficiency, charge transfer efficiency... OCam includes a low noise preamplifier stage, a digital board to generate the clocks and a microcontroller. The data acquisition system includes a user friendly timer file editor to generate any type of clocking scheme. A second version of OCam, called OCam², was designed offering enhanced performances, a completely sealed camera package and an additional Peltier stage to facilitate operation on a telescope or environmentally rugged applications. OCam² offers two types of built-in data link to the Real Time Computer: the CameraLink industry standard interface and various fiber link options like the sFPDP interface. OCam² includes also a modified mechanical design to ease the integration of microlens arrays for use of this camera in all types of wavefront sensing AO system. The front cover of OCam² can be customized to include a microlens exchange mechanism.

For adaptive optics systems, there is a growing demand for wavefront sensors that operate at higher frame rates and with more pixels while maintaining low readout noise. Lincoln Laboratory has been investigating Geiger-mode avalanche photodiode arrays integrated with CMOS readout circuits as a potential solution. This type of sensor counts photons digitally within the pixel, enabling data to be read out at high rates without the penalty of readout noise. After a brief overview of adaptive optics sensor development at Lincoln Laboratory, we will present the status of silicon Geigermode- APD technology along with future plans to improve performance.

Laser Tomographic systems, such as ATLAS, will rely on natural guide stars (NGS) to sense low order perturbation. This low order perturbation contains low order turbulence and Telescope Windshake, which strength lead to NGS wave front sensor (WFS) frame rate of several hundred Hertz. Therefore, the ability of the NGS WFS to deliver precise low order measurements in low signal to noise conditions will drive the limit magnitude of the NGS, hence the sky coverage. We have investigated the use of a focal plane sensor for this purpose, and consider it as the most efficient sensor in this context. We propose LIFT (LInearized Focal-plane Technique), and compare it to classical sensors, such as Quad Cell WFS, Pyramid WFS and Shack-Hartmann WFS. We derive an analytic model of the noise propagation law, which we validate on End-to-End diffractive simulations, based on realistic phase screens.

The Subaru Coronagraphic Extreme AO project (SCExAO) is a high performance coronagraph designed to deliver high contrast at small angular separation. For the detection of structures near the diffraction limit, an accurate control of low order wavefront aberrations - tip-tilt and focus - is essential as these aberrations create light leaks that are the source of confusion in the final science image. To address this major difficulty, we have equipped SCExAO with a specially designed Coronagraphic Low Order WaveFront Sensor (CLOWFS) using defocused images of a reflective ring located in the focal plane, that can track tip-tilt errors as small as 10^-3λ/D. CLOWFS was originally designed to drive actuators in a closed-loop. Here, we show that it can also be used in post-processing to efficiently subtract the tip-tilt induced coronagraphic leaks in the final science image.

Since the early days, many aspects of Adaptive Optics (AO) have seen tremendous changes. From the early experimental systems providing low order correction in a tiny patch of sky to todays fully automated specialized system offering correction in a much wider field and/or a much higher degree of correction, the evolution has been remarkable. For example, deformable mirror (DM) technology and wavefront sensing methods have been constantly improved. As well, real-time control algorithms have been greatly refined. This paper will review the different real-time control strategies that have been used with astronomical adaptive optics. They all have in common the same objective, that is the derivation of an optimal command for the deformable mirror(s) in order to get the least amount of residual optical aberrations in the science path. Most of the time, the real-time control algorithm is split in two independent components, the first part performing the wavefront (spatial) reconstruction, the second part performing the temporal control. With the advent of the extremely large telescopes (ELTs), as well as new AO modalities requiring several DMs and wavefront sensors, performing both these tasks in an ever shrinking glimpse of time is even more challenging. We will describe advanced fast and iterative reconstruction methods recently proposed for next generation AO systems. We will show how these algorithms combined with sparse matrices and parallel computing techniques meet the requirements of Extremely Large Telescope (ELT) real time computers.

We present the minimum variance control solution for an AO system featuring several NGS/LGS wavefront sensors operating at different sampling rates. We show that the optimal solution is based on a non-stationary Kalman filter. A simple sequential implementation is proposed, with one update equation per sensor. A stationary suboptimal solution is also derived.

ARGOS is the ground layer adaptive optics system planned for the LBT. The goal of such a ground layer adaptive optics system is to provide a maximum homogeneity of the point spread function over the full field of view. Controllers for optimized correction with an adaptive optics system with guide star and science target at different field angles are well known in the case of a single guide star. As ARGOS uses three laser guide stars and one auxiliary natural guide star a weighting scheme is required to optimize the homogeneity using all available information. Especially the tip and tilt modes measured by the one single off axis guide star and estimated thereof over the field will need to be improved by incorporation of the laser measurements. I will present the full scheme for an optimized controller for the ARGOS system. This controller uses the wavefront signals of the three lasers to additionally reconstruct the lower atmosphere. Information on the higher atmosphere will be provided by a DIMM-MASS instrument. The control scheme is tested analytically and the variation of the point spread function is then measured over the full field.

The Keck Next Generation Adaptive Optics (KNGAO) system promises to yield high-Strehl observations over a wide range of science wavelengths from the optical through the infrared. We describe the algorithms proposed for a Real-Time Controller (RTC) implemented in a massive parallel processor environment. These algorithms take advantage of the Fourier domain to speed up processing and ensure minimum variance control that incorporates prior as well as current data. We present the unique approach to the design that enables such a complex tomography processor to scale more favorably with telescope aperture size than the more traditional RTC approaches.

In recent years various researchers have proposed an optimal control approach for the rejection of turbulence-induced wavefront distortions in an AO system. The essential element in the design of an optimal controller is the choice for the turbulence model, which predicts the turbulence to compensate for the inherent delay in the AO control loop. In this paper various models as proposed in literature are considered; ranging from first order temporal models to high-order full spatialtemporal models. The various models are analyzed and the resulting 1-step ahead predictors are derived. The performance of the predictors are compared for a von Kármán type of turbulence with frozen flow propagation in and time-varying propagation directions.

In this paper, we present different methods of simulating AO systems, and show how these simulation tools have evolved in the last years. The evolutions have been driven by new projects (like more complex MCAO systems) and new telescopes (especially ELTs). These developments have been made in several directions: increasing simulation speed, complexity (more effects taken into account) and integrating the latest developments in algorithms. We will also discuss new directions in simulations, like new applications and new ways of estimating AO system performance.

In this paper we show why a non-linear curvature wavefront sensor (nlCWFS) is superior to both Shack-Hartmann wavefront sensor (SHWFS) and conventional curvature wavefront sensor (cCWFS) for sensing mV < 15 natural guide stars. We have developed an experimental setup aimed at comparing the the rms wavefront error obtained with the nlCWFS and the SHWFS. We describe our experimental setup and present results from the laboratory demonstration of the nlCWFS. The non-linear approach builds on the successful curvature wavefront sensing concept. The wavefront is reconstructed from the defocused pupil images using the Gerchberg-Saxton (GS) phase diversity algorithm. We compare results obtained from reconstructing the wavefront using a Shack-Hartmann wavefront sensor (SHWFS) and a nlCWFS for a monochromatic source. We discuss approaches to overcome non-linearity issues and discuss the challenge of using two WFSs in the same spatiotemporal control regime and the implementation of the nlCWFS on the 6.5 m MMT.

In this paper we present the results of a study comparing the performance of various centroiding methods on an extended spot. Various spot shapes, in good agreement with measurements of the Sodium layer density profile are investigated. We compare the performance of center-of-gravity (COG) based ad cross-correlation (CC) based methods and the matched filter (MF) algorithm. While their performance are comparable in the case of a Gaussian Sodium profile, we show that, above 15 to 20m off-axis, substantial differences appear in the case of a known non-Gaussian Sodium density profile. CC based and MF methods seem to have comparable or better performance with various spot shapes while non-Gaussian shapes have dramatic impact on COG based methods.

Increasing dimensions of ground based telescopes and adaptive optics needs for these instruments require wide deformable mirrors with a high number of actuators to compensate the effects of the atmospheric turbulence on the wave fronts. The new dimensions and characteristics of these deformable mirrors lead to the apparition of structural vibrations, which may reduce the rejection band width of the adaptive optics control loop. The aim of this paper is the study of the dynamic behavior of a 1-meter prototype of E-ELT's deformable mirror in order to identify its eigenmodes and to propose some ways to control its vibrations. We first present the first eigenmodes of the structure determined by both finite element analysis and experimental modal analysis. Then we present the frequency response of the prototype to a tilt excitation to estimate the effects of its vibrations on the adaptive optics loop. Finally we suggest a method to control the dynamics of the deformable mirror.

Open-loop adaptive optics is a technique in which the turbulent wavefront is measured before it hits the deformable mirror for correction; therefore the correct control of the mirror in open-loop is key in achieving the expected level of correction. In this paper, we present non-parametric estimation techniques to model deformable mirrors working in open-loop. We have results with mirrors characterized by non-linear behavior: a Xinetics electrostrictive mirror and a Boston Micromachines MEMS mirror. The inputs for these models are the wavefront corrections to apply to the mirror and the outputs are the set of voltages to shape the mirror. We have performed experiments on both mirrors, achieving Go-To errors relative to peak-to-peak wavefront excursion in the order of 1 % RMS for the Xinetics mirror and 3 % RMS for the Boston mirror . These techniques are trained with interferometric data from the mirror under control; therefore they do not depend on the physical parameters of the device.

The IMAKA project is a ground layer corrected wide field visible imager proposed for CFHT. It consists of three processes or components: The dome and local turbulence will be controlled by ventilation; the remaining ground layer turbulence will be corrected by a GLAO system and the free atmosphere seeing will be locally reduced by using an Orthogonal Transfer CCD to correct for tip-tilt within the isokinetic angle of field stars. In designing the AO system, whether based on an adaptive secondary mirror or using pupil relay optics, it becomes apparent that the conjugation of the deformable mirror is a difficult constraint to achieve given the large field. It turns out this problem is not isolated to IMAKA, because the Lagrange Invariant for our project is in the same range as that of EAGLE on the E-ELT for example. The effects of tilting the deformable mirror with respect to the pupil or compensating for misconjugation of an adaptive secondary mirror using a tomographic reconstructor have been investigated using Monte-Carlo simulation codes, including our code developed specifically for GLAO simulations. We report on quantitative results from IMAKA simulations for a variety of realistic turbulence conditions for each topical scheme, and allude to how these results are applicable to ELTs' adaptive optics.

In the context of the SPHERE planet finder project, we further develop and characterize a recently proposed method for the efficient direct detection of exoplanets from the ground using spectral and angular differential imaging. The method, called ANDROMEDA, combines images appropriately into "pseudo-data", then uses all of them in a Maximum-Likelihood framework to estimate the position and flux of potential planets orbiting the observed star. The method's performance is assessed on realistic simulations of images performed by the SPHERE consortium, and it is applied to experimental data taken by the VLT/NAOS-CONICA instrument.

We present the results of an on-sky point spread function reconstruction (PSF-R) experiment for the Gemini North telescope adaptive optics system, Altair, in the simplest mode, bright on-axis natural guise star. We demonstrate that our PSF-R method does work for system performance diagnostic but suffers from hidden telescope and system aberrations that are not accounted for in the model, making the reconstruction unsuccessful for Altair, for now. We discuss the probable origin of the discrepancy. In the last section, we propose alternative PSF-R methods for future multiple natural and laser guide stars systems.

We describe several projects addressing the growth of galaxies and massive black holes, for which adaptive optics is mandatory to reach high spatial resolution but is also a challenge due to the lack of guide stars and long integrations. In each case kinematics of the stars and gas, derived from integral field spectroscopy, plays a key role. We explain why deconvolution is not an option, and that instead the PSF is used to convolve a physical model to the required resolution. We discuss the level of detail with which the PSF needs to be known, and the ways available to derive it. We explain how signal-to-noise can limit the resolution achievable and show there are many science cases that require high, but not necessarily diffraction limited, resolution. Finally, we consider what requirements astrometry and photometry place on adaptive optics performance and design.

Although many methods have been proposed for the detection of exoplanets with adaptive optics, the problem of measuring their brightness is relatively neglected. We propose a novel, reference-less technique, which we call "PDF deconvolution", where the traditional 2-D image deconvolution is replaced by a 1-D time-series deconvolution. We present examples of its excellent accuracy on real and simulated adaptive optics observations with 3-8m apertures.

Large ground-based telescopes equipped with adaptive optics (AO) systems have ushered in a new era of highresolution infrared photometry and astrometry. Relative astrometric accuracies of <0.2 mas have already been demonstrated from infrared images with spatial resolutions of 55-95 mas resolution over 10-20" fields of view. Relative photometric accuracies of 3% and absolute photometric accuracies of 5%-20% are also possible. I will review improvements and current limitations in astrometry and photometry with adaptive optics of crowded stellar fields. These capabilities enable experiments such as measuring orbits for brown dwarfs and exoplanets, studying our Galaxy's supermassive black hole and its environment, and identifying individual stars in young star clusters, which can be used test the universality of the initial mass function.

The Angular, Simultaneous Spectral and Reference Star Differential Imaging techniques (ADI, SSDI and RSDI) are currently the main observing approaches that are being used to pursue large-scale direct exoplanet imaging surveys and will be a key component of next-generation high-contrast imaging instrument science. To allow detection of faint planets, images from these observing techniques are combined in a way to retain the planet flux while subtracting as much as possible the residual speckle noise. The LOCI algorithm is a very efficient way of combining a set of reference images to subtract the noise of a given image. Although high contrast performances have been achieved with ADI/SSDI/RSDI & LOCI, achieving high accuracy photometry and astrometry can be a challenge, due to various biases coming mainly from the inevitable partial point source self-subtraction for ADI/SSDI and how LOCI is designed to suppress the noise. We present here several biases that we hare uncovered while analyzing data on the HR8799 planetary system and how we have modified our analysis pipeline to calibrate or remove these effects so that high accuracy astrometry and photometry is achievable. In addition, several new upgrades are presented in a new archive-based (i.e. performing ADI, SSDI and RSDI with LOCI as a single PSF subtraction step) multi-instrument reduction and analysis pipeline called SOSIE.

Our team is carrying out a multi-year observing program to directly image and characterize young extrasolar planets using the Near-Infrared Coronagraphic Imager (NICI) on the Gemini-South 8.1-meter telescope. NICI is the first instrument on a large telescope designed from the outset for high-contrast imaging, comprising a high-performance curvature adaptive optics (AO) system with a simultaneous dual-channel coronagraphic imager. Combined with state-of-the-art AO observing methods and data processing, NICI typically achieves ≈2 magnitudes better contrast compared to previous ground-based or space-based planet-finding efforts, at separations inside of ≈2". In preparation for the Campaign, we carried out efforts to identify previously unrecognized young stars as targets, to develop a rigorous quantitative method for constructing our observing strategy, and to optimize the combination of angular differential imaging and spectral differential imaging. The Planet-Finding Campaign is in its second year, with first-epoch imaging of 174 stars already obtained out of a total sample of 300 stars. We describe the Campaign's goals, design, target selection, implementation, on-sky performance, and preliminary results. The NICI Planet-Finding Campaign represents the largest and most sensitive imaging survey to date for massive (>~ 1 MJup) planets around other stars. Upon completion, the Campaign will establish the best measurements to date on the properties of young gas-giant planets at -> 5-10 AU separations. Finally, Campaign discoveries will be well-suited to long-term orbital monitoring and detailed spectrophotometric followup with next-generation planet-finding instruments.

Extreme adaptive optics systems (XAO) dedicated to the search for extrasolar planets are currently being developed for 8-10 meter telescopes. The High-Order Test bench (HOT) is a high-contrast imaging adaptive optics bench developed at the European Southern Observatory to test and optimize different techniques and technologies (e.g. wavefront sensors, coronagraphs, speckle calibration methods, image post-processing). It reproduces realistic conditions at a telescope (e.g. Very Large Telescope, VLT), including a turbulence generator, a high-order adaptive optics system, a near-IR coronagraph, and sequential differential imaging modes (spectral and polarimetric). We discuss the results of XAO coronagraphy obtained in the laboratory in the context of imminent planet-finder instruments (e.g. SPHERE¹, GPI², and HiCIAO³). In particular, results obtained with HOT will be discussed and compared with contrast goals of the near-IR camera of SPHERE.

ESO and a large European consortium completed the phase-A study of EPICS, an instrument dedicated to exoplanets direct imaging for the EELT. The very ambitious science goals of EPICS, the imaging of reflected light of mature gas giant exoplanets around bright stars, sets extremely strong requirements in terms of instrumental contrast achievable. The segmented nature of an ELT appears as a very large source of quasi-static high order speckles that can impair the detection of faint sources with small brightness contrast with respect to their parent star. The paper shows how the overall system has been designed in order to maximize the efficiency of quasi-static speckles rejection by calibration and post-processing using the spectral and polarization dependency of light waves. The trade-offs that led to the choice of the concepts for common path and diffraction suppression system is presented. The performance of the instrument is predicted using simulations of the extreme Adaptive Optics system and polychromatic wave-front propagation through the various optical elements.

At the University of California's Lick Observatory, we have implemented an on-sky testbed for next-generation adaptive optics (AO) technologies. The Visible-Light Laser Guidestar Experiments instrument (ViLLaGEs) includes visible-light AO, a micro-electro-mechanical-systems (MEMS) deformable mirror, and open-loop control of said MEMS on the 1-meter Nickel telescope at Mt. Hamilton. (Open-loop in this sense refers to the MEMS being separated optically from the wavefront sensing path; the MEMS is still included in the control loop.) Future upgrades include predictive control with wind estimation and pyramid wavefront sensing. Our unique optical layout allows the wavefronts along the open- and closed-loop paths to be measured simultaneously, facilitating comparison between the two control methods. In this paper we evaluate the performance of ViLLaGEs in openand closed-loop control, finding that both control methods give equivalent Strehl ratios of up to ~ 7% in I-band and similar rejection of temporal power. Therefore, we find that open-loop control of MEMS on-sky is as effective as closed-loop control. Furthermore, after operating the system for three years, we find MEMS technology to function well in the observatory environment. We construct an error budget for the system, accounting for 130 nm of wavefront error out of 190 nm error in the science-camera PSFs. We find that the dominant known term is internal static error, and that the known contributions to the error budget from open-loop control (MEMS model, position repeatability, hysteresis, and WFS linearity) are negligible.

We describe the design and development status of GRAAL, the Ground-layer adaptive optics assisted by Laser, which will deliver enhanced images to the Hawk-I instrument on the VLT. GRAAL is an adaptive optics module, part of AOF, the Adaptive optics facility, using four Laser- and one natural guide-stars to measure the turbulence, and correcting for it by deforming the adaptive secondary mirror of a Unit telescope in the Paranal observatory. The outstanding feature of GRAAL is the extremely wide field of view correction, over 10 arcmin diameter, with an image enhancement of about 20% in average in K band. When observing GRAAL will provide FWHM better than 0.3" 40% of the time. Besides the Adaptive optics facility deformable mirror and Laser guide stars, the system uses subelectron L3-CCD and a real-time computing platform, SPARTA. GRAAL completed early this year a final design phase shared internally and outsourced for its mechanical part by the Spanish company NTE. It is now in manufacturing, with a first light in the laboratory planned in 2011.

The PALM-3000 upgrade to the Palomar Adaptive Optics system will deliver extreme adaptive optics correction to a suite of three infrared and visible instruments on the 5.1 meter Hale telescope. PALM-3000 uses a 3388-actuator tweeter and a 241-actuator woofer deformable mirror, a wavefront sensor with selectable pupil sampling, and an innovative wavefront control computer based on a cluster of 17 graphics processing units to correct wavefront aberrations at scales as fine as 8.1 cm at the telescope pupil using natural guide stars. Many components of the system, including the science instruments and a post-coronagraphic calibration wavefront sensor, have already been commissioned on the sky. Results from a laboratory testbed used to characterize the remaining new components and verify all interfaces are reported. Deployment to Palomar Observatory is planned August 2010, with first light expected in early 2011.

We present up-to-date performance characteristics for natural guide star (NGS) operation of the ALTAIR adaptive optics system at the Gemini N. 8m telescope. These results are obtained from a nightly performance monitoring campaign where we obtain a consistent set of point spread functions (PSFs) over a broad range of observing conditions. These results are compared with system modelling and circular buffer information from the Altair adaptive optics (AO) system. The latter show residual tip-tilt errors with a median rms ~ 18.5 mas. We also present preliminary results from a new operational mode of the laser guide star (LGS) AO which will eventually yield all-sky access with image FWHM ~ 0.1" - 0.2".

LINC-NIRVANA is the near-infrared homothetic imaging camera for the Large Binocular Telescope. Once operational, it will provide an unprecedented combination of angular resolution, sensitivity and field of view. Its layer-oriented MCAO systems (one for each arm of the interferometer) are conjugated to the ground layer and an additional layer in the upper atmosphere. In this contribution MCAO wavefront control is discussed in the context of the overall control scheme for LINC-NIRVANA. Special attention is paid to a set of auxiliary control tasks which are mandatory for MCAO operation: The Fields of View of each wavefront sensor in the instrument have to be derotated independent from each other and independently from the science field. Any wavefront information obtained by the sensors has to be matched to the time invariant modes of the deformable mirrors in the system. The tip/tilt control scheme is outlined, in which atmospheric, but also instrumental tip/tilt corrections are sensed with the high layer wavefront sensor and corrected by the adaptive secondary mirror of the LBT. Slow image motion effects on the science detector have to be considered, which are caused by flexure in the non-common path between AO and the science camera, atmospheric differential refraction, and alignment tolerances of the derotators. Last but not least: The sensor optics (pyramids) have to be accurately positioned at the images of natural reference stars.

In this paper we present the rationale and design of a compact, transportable, modular Laser Guide Star Unit, comprising a 589nm laser mounted on a 300mm launch telescope, to be used in future experiments probing the mesospheric sodium properties and to validate existing LGS return flux simulations. The 20W CW 589nm Laser is based on the ESO developed concept of 589nm lasers based on Raman Fiber Amplifiers, refined and assembled together with industry. It has the same laser architecture as the laser which will be used for the VLT Adaptive Optics Facility. We have added to the 20W CW laser system the capabilities of changing output polarization, D2b emission levels, power level, linewidth and to operate as pulsed laser with amplitude modulation. We focus in this paper on the laser description and test results.

With the much anticipated delivery of the Lockheed Martin Coherent Technology Quasi-CW laser, the W. M. Keck Observatory was able to complete the installation and integration of the Laser Guide Star Adaptive Optics System on the Keck I telescope. The Keck I LGSAO system was developed to provide redundancy for the Keck II system as well as balancing the instrumentation load between the two telescopes and interferometers. With the improved sodium coupling efficiency of the laser and a center launching system, the Keck I laser performance is expected to exceed those on the Keck II system. We present the challenges of integrating the Keck I Laser Guide Star Adaptive Optics System on an operational telescope. We will present issues and performance data related to the primary subsystem components such as the laser itself, the Selex Galileo Avionica launch telescope, the Mitsubishi fiber transport, and the Adaptive Optics System. The paper will also focus on the integration and testing performed at the W. M. Keck headquarters as well as the summit of Mauna Kea. We will present initial first light performance of the Keck I LGSAO System and compare those to the existing Keck II LGSAO System.

ELP-OA ('Etoile Laser Polychromatique pour l'Optique Adaptative) aims at demonstrating the tip-tilt is measurable with a Laser Guide Star (LGS) without any natural guide star. This allows a full sky coverage down to visible wavelengths. ELP-OA is being setup at Observatoire de Haute-Provence (OHP). To create a polychromatic LGS, we use two pulsed dye lasers (at 569nm and 589nm) to produce a two-photons excitation of sodium atoms in the mesosphere. The chromatism of the refractive index of the air yields a difference of the LGS direction at different wavelengths. The position differences is proportionnal to the tip-tilt. Since the LGS isn't sharp enough to give us a small enough error in the differential tip-tilt, we use an interferometric projector to improve the high spatial information in the laser spot. It requires an adaptive optics working down to 330nm. This one is done by post-processing algorithms. Two two aperture projectors are used. Each one creates a fringe-modulated LGS, and a better RMS error in the LGS position is obtained by measuring the information in a normal direction with respect to the fringes. By using a two aperture projector, we also strongly decrease the negative effect of the laser star elongation in the mesosphere, and the Rayleigh contribution near the LGS. We propose a new optimal algorithm to retrieve the tip-tilt from simultaneous images at different wavelengths. To enhance the RMS error of the measurements, we extend this algorithm to exploit the temporal correlation of the turbulence.

We demonstrate for the first time the practical feasibility of a new sodium guide star laser with a pulsed burst output of sufficient energy at 589nm to be useful for current applications and readily scalable to meet future requirements. We describe complete experimental design verification results of the pulse burst laser concept, optimized to eliminate guide-star elongation issues and to meet all requirements for Multi Conjugate Adaptive Optics (MCAO) for future extremely large ground-based telescopes (ELTs). It makes use of sum frequency generation (SFG) of two, Q-switched, injection mode-locked, wavelength stabilized Nd:YAG lasers, producing a macro-micro, pulse-burst output which is optimized in power and bandwidth to maximize the fluorescence from the high altitude sodium layer.

We report on the successful delivery of a 30 W solid-state sodium Guide Star Laser System (GLS) to the W. M. Keck Observatory in 2009, and the demonstration of a 55 W GLS delivered to the Gemini South Observatory in 2010. This paper describes the GLS performance results of both the Keck I and Gemini South GLSs with an emphasis on the system design and delivered performance. The 589 nm output was generated via Sum Frequency Mixing (SFM) of 1064 nm and 1319 nm Nd:YAG lasers in a LBO (Lithium Triborate) nonlinear crystal. The Keck GLS underwent extensive testing and has demonstrated consistent performance with a CW mode-locked output of > 30 W and measured beam quality of M² < 1.2 while locked to the sodium D2a transition. The Keck GLS was installed on the telescope in late 2009 and first light on the sky was achieved in early 2010. Factory testing of the Gemini South GLS shows a CW modelocked output of > 55 W and measured M² ~1.2 while locked to the sodium D2a line center. The Gemini South GLS has produced a maximum power of 76 W at 589 nm with 85 W of 1319 nm and 110 W of 1064 nm as inputs to the SFM, representing a single-pass conversion efficiency of 39%.

With the development of increasingly larger and more complex telescopes and instrumentation, site testing and characterization efforts also increase in both magnitude and complexity. This happens because the investment into larger observatories is higher and because new technologies, such as adaptive optics, require knowledge about parameters that did not matter previously, such as the vertical distribution of turbulence. We present examples of remaining questions which, to date, are not generally addressed by "standard" site characterization efforts, either because they are technically not (yet) feasible or because they are impractical. We center our observations around the experience gained during the Thirty Meter Telescope (TMT) site testing effort with an emphasis on turbulence measurements, but our findings are applicable in general to other current and future projects as well.

Variations in density structure and altitude of mesospheric sodium impact the performance of adaptive optics systems employing sodium laser guide stars. The associated wave-front errors grow as the square of the telescope aperture and will be very significant for the next generation of large-aperture ground-based optical/infrared telescopes. To support the adaptive optics program for the Thirty Meter Telescope and European Extremely Large Telescope, we are conducting a program of sodium monitoring using a high-resolution sodium lidar system on the 6-meter Large Zenith Telescope (LZT). Located at 49°N latitude, the LZT lidar system provides density profiles with spatial and temporal resolution sampling of 4.8 m and 20 ms. In this paper we report highlights of results obtained over two years of observations.

The quest of the astronomical instrumentation community for high-power, narrow-band CW laser guide stars (LGS) has been a challenge to the laser community for more than two decades now. Only recently, a new generation of rugged laser system developments has started to provide the laser infrastructure for the next generation earth-bound telescopes. We report on the system design of four 20W CW diode-seeded fiber-amplified laser guide star for deployment at the VLT in 2013.

Ground Layer Adaptive Optics (GLAO) is a relatively novel form of AO designed to provide image improvements over fields of view of ~10' or greater. A representative range of GLAO instrumentation projects from 4m to 42m are summarised. A related form of wide field AO is Multi-Object Adaptive Optics (MOAO). Here, much higher correction is required, but only for sparsely distributed "islands". The correction is applied in open-loop, and this feature, plus the high accuracy, wide field tomography required, mean that MOAO involves considerable technological development. Several pathfinders, as well as actual MOAO facility projects, are underway, and are surveyed here.

In the past decade the ingredients for making real an Extremely Large Telescope with an Adaptive Optics system driven solely by Natural Guide Stars have been conceived, developed, built and proven on the sky. Still, the straightforward merging of these concepts is not enough to fulfill such an ambitious goal. We show here that a combination of the layeroriented approach, the virtual deformable mirrors concept, and a combined use of different kind of wavefront sensors, some taking advantage of working in Closed Loop and some other characterized by an extremely high dynamic range, make the goal a reachable one. It is remarkable that such an approach requires, on a telescope of ELT class, including a common Deformable Mirror conjugated to the entrance pupil or close-by, a minimum impact on the guide probe units. The last involves the adoption of small Closed Loop AO system with an extremely high dynamic range wavefront sensor looking at the detailed shape of a small Deformable Mirror that allows the use of sensors taking advantage of the Closed Loop conditions. A pyramid wavefront sensor, fed by the Natural Guide Stars light and closing the loop with the mirror, and a YAW wavefront sensor looking at the mirror itself, allow for a natural and efficient combination of the data. The limits in the Field of View covered by such an approach are given by pure meta-pupils superimposition rather than to the spatial frequency of the achievable correction, breaking the limits previously thought for this kind of systems. The overall combination leads to a significant sky coverage, with performances comparable to the ones under discussion for some Laser Guide Stars approaches, without the related hurdle. The small technical impact on the telescope makes this approach not directly in-conflict with a Laser Guide Stars one allowing the designer to keep all the options on the table up to a very late stage.

The Subaru Coronagraphic Extreme-AO (SCExAO) system is designed for high contrast coronagraphic imaging at small angular separations, and is scheduled to see first light on the Subaru Telescope in early 2011. The wavefront control architecture for SCExAO is optimized for scattered light control and calibration at small angular separations, and is described in this paper. Key subsystems for the SCExAO wavefront control architecture have been successfully demonstrated, and we report results from these tests and discuss their role in the SCExAO system. Among these subsystems, a technique which can calibrate and remove static and slow speckles which traditionally limit high contrast detections is discussed. A visible light lab prototype system at Subaru Telescope recently demonstrated speckle halo reduction to 2e-7 contrast within 2 2λ/D, and removal of static coherent speckles to 3e-9 contrast.

Experience with the current generation of astronomical single laser guide star (LGS) adaptive optics (AO) systems has demonstrated system performance that is often limited by residual tip-tilt errors induced by the paucity of bright tip-tilt natural guide stars (NGS). To overcome this limitation, we are developing a new generation of tip-tilt sensors that will operate at near-infrared wavelengths where the NGS is sharpened to the diffraction limit. To optimize performance, single LGS AO systems utilizing sharpened tip-tilt NGS should generally not point their LGS directly toward their science target. Rather, optimal performance for wide sky coverage is obtained by offsetting LGS pointing along a radius connecting the science target and the tip-tilt NGS. We demonstrate that determination of the jointly optimized LGS pointing angle and tip-tilt wavefront sensor (WFS) integration time can improve performance metrics by factors of several, particularly for faintest NGS operation. We find the LGS offset should be as much as 1/2 the distance to the NGS to maximize Strehl ratio at near-infrared wavelengths and ≈ 1/4 the distance to the NGS to maximize ensquared energy, with lesser off-pointing for brighter NGS. Future AO systems may benefit from predictive determination of optimal LGS offsetting, based upon changing atmospheric conditions and observational geometries.

A critical goal in the next decade is to develop techniques that will extend Adaptive Optics correction to visible wavelengths on Extremely Large Telescopes (ELTs). We demonstrate in the laboratory the highly accurate atmospheric tomography necessary to defeat the cone effect on ELTs, an essential milestone on the path to this capability. We simulate a high-order Laser Tomographic AO System for a 30-meter telescope with the LTAO/MOAO testbed at UCSC. Eight Sodium Laser Guide Stars (LGSs) are sensed by 99x99 Shack-Hartmann wavefront sensors over 75". The AO system is diffraction-limited at a science wavelength of 800 nm (S ~ 6-9%) over a field of regard of 20" diameter. Openloop WFS systematic error is observed to be proportional to the total input atmospheric disturbance and is nearly the dominant error budget term (81 nm RMS), exceeded only by tomographic wavefront estimation error (92 nm RMS). The total residual wavefront error for this experiment is comparable to that expected for wide-field tomographic adaptive optics systems of similar wavefront sensor order and LGS constellation geometry planned for Extremely Large Telescopes.

Variations of the sodium layer altitude and atom density profile induce errors on laser-guide-star (LGS) adaptive optics systems. These errors must be mitigated by (i), optimizing the LGS wavefront sensor (WFS) and the centroiding algorithm, and (ii), by adding a high-pass filter on the LGS path and a low-bandwidth natural-guide-star WFS. In the context of the ESO E-ELT project, five centroiding algorithms, namely the centre-of-gravity (CoG), the weighted CoG, the matched filter, the quad-cell and the correlation, have been evaluated in closedloop on the University of Victoria LGS wavefront sensing test bed. Each centroiding algorithm performance is compared for a central versus side-launch laser, different fields of view, pixel sampling, and LGS flux.

Adaptive Optics (AO) relies on aWave Front Sensor (WFS) to measure properly the perturbations induced by the turbulence on the wavefront. Yet, source extension may limit its performance. In the case of a Shack-Hartmann (SH) WFS associated to one or more Laser Guide Stars (LGS), this extension becomes all the more problematic as the diameter of the telescope tends to increase. In order to mitigate the effects induced by the spot elongation on the quality of the WFS measurements, various algorithms are used. Most of them are non-linear, and require a reference. The design of the SH WFS itself has an influence on the measurement quality, as it also induces non-linearities. In addition, the time-evolving structure of the LGS, due to the fluctuations of the Sodium layer, has an impact on the measurements as well. Eventually, both influences are coupled in the wavefront sensing process. The present study is aimed at optimizing a whole set of carefully chosen parameters defining the design of a SH WFS, in the particular case of a LGS on an ELT. The relative impact of these parameters are studied first at the subaperture level, and then on the reconstructed wavefront.

Phase Diversity is a focal-plane technique which is chromatic by nature. The use of a monochromatic model on wide-band imaging results of an additional error function of the spectral range.We present here a second order modeling of the focal plane wave-front sensing error due to wide-band imaging and propose a first order correction by inverse problem and the first results of an end-to-end simulation for an iterative correction. Simulation results of 20 nm wave-front aberrations show that the reconstruction error decreases from 10 nm with classical focal-plane sensor to sub-nanometric error with optimal correction at Δλ = 500 nm.

In this communication we address the problem of post coronagraphic wavefront reconstruction. In high contrast imaging applications it is crucial to estimate the wavefront after the coronagraph, as close as possible to the science camera, in order to minimize non-common path errors. However closing the loop on such a measurement is a difficult exercise since several low order modes have been cancelled by the coronagraphs, thus leading to ill-posed inversion problems. Moreover sensing at the science detector is an intrusive method that disrupts the course of the observations. The Gemini Planet Imager (GPI) calibration system, based on a post-coronagraphic interferometer, provides an estimate of mid to high spatial frequencies aberrations that alleviates these two issues. However such a measurement have an intrinsic limitations that is related to the differential path errors between the two arm of the interferometer. In this paper we show how to devise wavefront reconstruction algorithms that account for these differential path errors. We identify two regimes, relative and absolute wavefront sensing, that depend on the magnitudes of the aberrations and the design of the coronagraph. We illustrate the performances for each regime. Finally we present experimental results obtained during the validation phase of show the results on laboratory data.

The contactless, voice coil motor adaptive mirror technology starts from an idea by Piero Salinari in 1993. This idea has progressively evolved to real systems thanks to a fruitful collaboration involving Italian research institutes (INAF - Osservatorio Astrofisico di Arcetri and Aerospace Department of Politecnico di Milano) and small Italian enterprises (Microgate and ADS). Collaboration between research institutions and industry is still very effectively in place, but nowadays the technology has left the initial R&D phase reaching a stage in which the whole projects are managed by the industrial entities. In this paper we present the baseline concept and its evolution, describing the main progress milestones. These are paced by the actual implementation of this idea into real systems, from MMT, to LBT, Magellan, VLT, GMT and E-ELT. The fundamental concept and layout has remained unchanged through this evolution, 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. Moreover, this concept has proved its expandability to very large systems with thousands of controlled d.o.f. Notwithstanding the solidity of the fundamentals, the implementation has strongly evolved from the beginning, in order to deal with the dimensional, power, maintainability and reliability constraints imposed by the increased size of the targeted systems.

The Large Binocular Telescope (LBT) has two adaptive secondary mirrors based on 672 voice-coil force actuators. The shape of the mirror is controlled using internal metrology based on co-located capacitive sensors. The first mirror unit is currently mounted on LBT for on-sky commissioning as part of the First Light Adaptive Optics System (FLAO). During spring-time 2009 the optical acceptance test was performed using the 14-m optical test tower at the Osservatorio Astrofisico di Arcetri (INAF) showing the capability of flattening the shell at the level of 14nm rms residual surface error. This paper reports the optical layout, calibration procedures and results of the optical acceptance test. Moreover we report the first results obtained during the early runs of FLAO commissioning showing the ability of the mirror to compensate for atmospheric turbulence with extremely high Strehl ratio values (better than 80% in H-band) as permitted by the largest number of correcting degrees of freedom currently available on-sky for astronomical telescopes.

We report on the development of high actuator count, micro-electromechanical (MEMS) deformable mirrors designed for high order wavefront correction in ground and space-based astronomical adaptive optics instruments. The design of these polysilicon, surface-micromachined MEMS deformable mirrors builds on technology that has been used extensively to correct for ocular aberrations in retinal imaging systems and for compensation of atmospheric turbulence in free-space laser communication. These light-weight, low power deformable mirrors have an active aperture of up to 25.2mm consisting of a thin silicon membrane mirror supported by an array of 140 to 4092 electrostatic actuators which exhibit no hysteresis and have sub-nanometer repeatability making them well suited for open-loop control applications such as Multi-Object Adaptive Optics (MOAO). The continuous membrane deformable mirrors, coated with a highly reflective metal film, are capable of up to 6μm of stroke, have a surface finish of <10nm RMS with a fill factor of 99.8%. Presented in this paper are device characteristics and performance test results, as well as reliability test data and device lifetime predictions that show that trillions of actuator cycles can be achieved without failures.

We describe the lab characterization of the new 3,388-actuator deformable mirror (DM3388) produced by Xinetics, Inc. for the PALM-3000 adaptive optics (AO) system1 under development by Jet Propulsion Laboratory and Caltech Optical Observatories. This square grid 66-by-66 actuator mirror has the largest number of actuators of any deformable mirror currently available and will enable high-contrast imaging for direct exoplanet imaging science at the Palomar 200" diameter Hale Telescope. We present optical measurements of the powered and unpowered mirror surface, influence functions, linearity of the actuators, and creep of the actuators. We also quantify the effect of changes in humidity.

CILAS proposes a M4 adaptive mirror (M4AM) that corrects the atmospheric turbulence at high frequencies and residual tip-tilt and defocus due to telescope vibrations by using piezostack actuators. The design presents a matrix of 7217 actuators (triangular geometry, spacing equal to 29 mm) leading to a fitting error reaching the goal. The mirror is held by a positioning system which ensures all movements of the mirror at low frequency and selects the focus (Nasmyth A or B) using a hexapod concept. This subsystem is fixed rigidly to the mounting system and permits mirror displacements. The M4 control system (M4CS) ensures the connection between the telescope control/monitoring system and the M4 unit - positioning system (M4PS) and piezostack actuators of the M4AM in particular. This subsystem is composed of electronic boards, mechanical support fixed to the mounting structure and the thermal hardware. With piezostack actuators, most of the thermal load is minimized and dissipated in the electronic boards and not in the adaptive mirror. The mounting structure (M4MS) is the mechanical interface with the telescope (and the ARU in particular) and ensures the integrity and stability of M4 unit subsystems. M4 positioning system and mounting structure are subcontracted to AMOS company.

Myst is the Gemini MCAO System (GeMS) high level control GUI. It is written in yorick, python and C. In this paper, we review the software architecture of Myst and its primary purposes, which are many: Real-time display, high level diagnostics, calibrations, and executor/sequencer of high level actions (closing the loop, coordinating dithers, etc).

SPARTA^TM, the ESO Standard Platform for Adaptive optics Real Time Applications, is the real time computing platform serving 3 major 2nd generation instruments at the VLT (SPHERE, GALACSI and GRAAL) with plans to serve more, smaller, instruments in the near future. SPARTA offers a very modular and fine-grained architecture which is generic enough to serve a variety of AO systems. SPARTA includes the definitions of all the interfaces between those modules and provides libraries and tools to implement and test the various modules as well as a map to technologies capable of delivering the required performance, most of them innovative with respect to ESO standards in use. For the above mentioned instruments, SPARTA provides also a complete implementation of the AO application, with features customized for each of the 3 instruments. In this paper we present the architecture of SPARTA, its technologies, functions, performance and test tools as well as the plans to increase the reach of the platform to smaller system with what we call SPARTA Light.

We give an overview of the Adaptive Optics (AO) and Multi-conjugate Adaptive Optics (MCAO) system of the planned 4m European Solar Telescope (EST). The parameter space and the problems of solar MCAO working in the visible are explained. The wavefront reconstruction schemes presently being considered are explained. First estimates of the expected MCAO performance for varying parameter sets are given.

NICI, the high-contrast coronagraphic imager of Gemini observatory, primarily dedicated to planet hunting has been offered to the astronomical community since end of 2008. We present our experiences in operating and maintaining NICI's 85 element curvature adaptive optics (AO) system. A detailed study of NICI AO telemetry data is also most relevant to prepare the arrival of next generation instruments. We summarize the behavior of interaction matrices, control matrices and error transfer functions under different operational conditions; a detailed understanding of the system helps monitoring and optimizing performance. Furthermore, we describe tuning (membrane mirror stroke/extra focal distance) for non-optimal seeing conditions as well as for niche applications of NICI such as observing small moons and asteroids. We compare on-sky measurements to theory or simulations.

We started adaptive optics (AO) development activities in Tohoku university targeting Multi-Object Adaptive Optics (MOAO) system for the next generation ground-based large telescopes. In order to realize an MOAO system, we are currently conducting two R&Ds. First one is a development of a large stroke (20μm) Micro Electro Mechanical Systems (MEMS) deformable mirror with large number of elements (>3000) which is necessary to achieve mild Strehl Ratio in an AO systems for 30m class telescopes. Based on our original design to achieve the requirements, prototyping of the device is currently underway using the MEMS development facility in our university. Second one is a consideration of tomographic algorithm for the wavefront estimation required for an MOAO system. The algorithm will be tested on a test bench simulating multiple guide stars and wavefront sensors. Concept design of the test bench is shown. MEMS-DM and MOAO testbed developments will be concluded by 2013.

We describe the opto-mechanical implementation of a group of wavefront sensors able to drive an MCAO system in order to cover a Field of View of the order of 1-2 arc-minutes, but getting advantages from the starlight coming from a Field of View as large as 10 arc-minutes in diameter. This involves a number of arms with a miniaturized, very small Field of View, single reference Adaptive Optics systems. A pyramid wavefront sensor working in close loop is fed through a small Deformable Mirror that is continuously monitored by an extremely high dynamic range wavefront sensor, whose signal has similar modality than the Pyramid one, namely YAW. In this way, a very compact wavefront sensor with a dynamic range limited by the stroke of the Deformable Mirror is achieved. Such a sensor is characterized by a limiting magnitude performances typical of a closed loop coherent wavefront sensor. This concept, in addition with an architecture of a Wavefront Computer that allows the implementation of a number of virtual Deformable Mirrors, allows for the development of a NGS based concept described elsewhere. Emphasis is given in this talk to the practical implementation and to the opto-mechanical details, including an overview of the required components, especially the detectors and the deformable mirrors and we show that the goal is attainable with today existing components.

This paper aims at giving an update on the most versatile Adaptive Optics fed instrument to date, the well known and successful NACO*. Although NACO is only scheduled for about two more years^† at the Very Large Telescope (VLT), it keeps on evolving with additional operation modes bringing original astronomical results. The high contrast imaging community uses it creatively as a test-bench for SPHERE^‡ and other second generation planet imagers. A new visible wavefront sensor (WFS) optimized for Laser Guide Star (LGS) operations has been installed and tested, the cube mode is more and more required for frame selection on bright sources, a seeing enhancer mode (no tip/tilt correction) is now offered to provide full sky coverage and welcome all kind of extragalactic applications, etc. The Instrument Operations Team (IOT) and Paranal engineers are currently working hard at maintaining the instrument overall performances but also at improving them and offering new capabilities, providing the community with a well tuned and original instrument for the remaining time it is being used. The present contribution delivers a non-exhaustive overview of the new modes and experiments that have been carried out in the past months.

We have created a new adaptive optics system using a holographic modal wavefront sensing method capable of autonomous (computer-free) closed-loop control of a MEMS deformable mirror. A multiplexed hologram is recorded using the maximum and minimum actuator positions on the deformable mirror as the "modes". On reconstruction, an input beam will be diffracted into pairs of focal spots - the ratio of particular pairs determines the absolute wavefront phase at a particular actuator location. The wavefront measurement is made using a fast, sensitive photo-detector array such as a multi-pixel photon counters. This information is then used to directly control each actuator in the MEMS DM without the need for any computer in the loop. We present initial results of a 32-actuator prototype device. We further demonstrate that being an all-optical, parallel processing scheme, the speed is independent of the number of actuators. In fact, the limitations on speed are ultimately determined by the maximum driving speed of the DM actuators themselves. Finally, being modal in nature, the system is largely insensitive to both obscuration and scintillation. This should make it ideal for laser beam transmission or imaging under highly turbulent conditions.

There is analyzed the possibility the general tilt correction of the wave front on base of the laser guide star (LGS) signal. The calculation of the image motion of the spherical wave (that position the source of radiation also fluctuated) with random center is conducted. The exact formula for random vector defining the position of the image of the spherical wave in focal plane of the telescope is offered. The variance of residual fluctuations has been calculated. The variance behavior of this residual motion from optical experiment parameters are analyses. The similar problem under solution of the some practical tasks, including the possibility of the wave front "global" tilt correction with using single LGS, can be appeared.

We present a method for online estimation and prediction of wavefront distortions caused by two independent layers of frozen flow turbulence. The key to this algorithm is a fast, gradient-based estimator that uses optical flow techniques to extract the bulk velocity vectors of the two wind layers from three consecutive measurements of their combined wavefront. Once these velocity vectors are known, the phase aberrations resulting from the two-layer atmosphere can be predicted at any future time using a linear combination of shifted wavefronts. This allows calculation of a deformable mirror correction that compensates for the time delay errors in the control loop. Predictive control will be especially beneficial for visible light and high-contrast astronomical adaptive optics as well as for any adaptive optics system whose performance suffers due to time delay errors. A multilayer approach to predictive control is necessary since most observing sites have multi-layer atmospheres. The spatial domain method that we present is attractive because it uses all spatial frequency components of the wavefront simultaneously to find a global wind model. Its ability to update the wind velocity estimate at each control cycle makes it sensitive to changes in the wind on the order of tens of milliseconds. Our simulations show a potential Strehl increase from 0.45 to 0.65 for visible-light adaptive optics in low-noise, moderate-wind conditions with two frozen-flow wind layers and a strong static layer.

In order to suppress the halo and any residual speckles over a region of interest, we find an anti-halo reconstructor which gives the required changes to a deformable mirror (DM) at the pupil plane. The reconstructor is built from a training set consisting of measurements of the complex halo influence functions for a spanning set of Fourier modes applied to the DM. The reconstructor is then found by multiplying the applied DM actuator values by the singular value decomposition (SVD) pseudo-inverse of the measured complex halo influence functions. Using a single fully illuminated 12×12 actuator DM at the pupil plane, halo suppression for complex pupils out to the control radius of 6 λ/D can be provided. In practice, a coronagraph is unlikely to achieve high performance without adaptive tuning. We use a coronagraphic focal plane interferometer [1], where the focal plane mask diverts the bright starlight for use as an interferometric reference beam to measure the residual complex halo. The result of the reconstructor acting on the complex halo measurements allowed us to implement a closed loop halo-suppression servo. We discuss the laboratory implementation and experience with this technique.

Adaptive pupil masking can be used to reduce the halo and increase the peak intensity of a point spread function (PSF) using an adaptive pupil mask. Areas of the pupil where the residual wavefront aberrations are large are selected and masked using a spatial light modulator. The technique can be used as a standalone system on a smaller telescope without adaptive optics or in conjunction with an adaptive optics system to further improve the PSF. We find by simulation that for a 1 m telescope and using an 8 × 8 system we can increase the peak intensity by 40 % and reduce the FWHM by 76 % to near the diffraction limit. For an 8 m class telescope with a 16×16 pupil mask and adaptive optics the intensity was found to increase by 23 % and the FWHM reduced from 0.022" to 0.018". We also examine the effects of the adaptive pupil mask on the diffraction limited PSF. The square blocking elements result in a square diffraction pattern superimposed on the standard circular diffraction pattern. The relative strengths of each depend on the fraction of the pupil which is blocked.

Many technical improvements have been made since we first introduced deformable mirrors that use magnetic liquids (ferrofluids) whose surface are shaped by arrays of small electric coils. We present recent advances and experimental results of a 91-actuator magnetic liquid deformable mirror that uses a novel technique that linearizes their response by placing the array of actuators inside a strong and uniform magnetic field. We show that this improved ferrofluid deformable mirror (FDM) can produce inter-actuator strokes of over 10 μm, is capable of generating wavefront having peak-to-valley amplitudes of over 60 μm, and predict that amplitudes greater than 100 μm are achievable. We also present experimental results showing that these improved FDMs are good candidates for astronomical, vision science, and optical testing applications.

The Magellan Adaptive Secondary AO system, scheduled for first light in the fall of 2011, will be able to simultaneously perform diffraction limited AO science in both the mid-IR, using the BLINC/MIRAC4 10μm camera, and in the visible using our novel VisAO camera. The VisAO camera will be able to operate as either an imager, using a CCD47 with 8.5 mas pixels, or as an IFS, using a custom fiber array at the focal plane with 20 mas elements in its highest resolution mode. In imaging mode, the VisAO camera will have a full suite of filters, coronagraphic focal plane occulting spots, and SDI prism/filters. The imaging mode should provide ~20% mean Strehl diffraction-limited images over the band 0.5-1.0 μm. In IFS mode, the VisAO instrument will provide R~1,800 spectra over the band 0.6-1.05 μm. Our unprecedented 20 mas spatially resolved visible spectra would be the highest spatial resolution achieved to date, either from the ground or in space. We also present lab results from our recently fabricated advanced triplet Atmospheric Dispersion Corrector (ADC) and the design of our novel wide-field acquisition and active optics lens. The advanced ADC is designed to perform 58% better than conventional doublet ADCs and is one of the enabling technologies that will allow us to achieve broadband (0.5-1.0μm) diffraction limited imaging and wavefront sensing in the visible.

ARGOS, the Laser Guide Star (LGS) facility of the Large Binocular Telescope (LBT), implements a Ground Layer Adaptive Optics (GLAO) system, using 3 low-altitude beacons, to improve the resolution over the 4'×4' FoV of the imager and Multi Object Spectrograph (MOS) LUCIFER. In this paper we discuss the performance and the reconstruction scheme of an hybrid AO system using the ARGOS Rayleigh beacons complemented with a single faint high-altitude star (NGS or sodium beacon) to sense the turbulence of the upper atmosphere allowing an high degree of on-axis correction. With the ARGOS system, the NGS-upgrade can be immediately implemented at LBT using the already existing Pyramid WFS offering performance similar to the NGS AO system with the advantage of a larger sky coverage.

The ability to simulate atmospheric turbulence is a crucial part of enabling adaptive optics technology to function and evolve. We report a new technique of creating phase plates developed at the Laboratory for Adaptive Optics (LAO) which involves the application of clear acrylic paint onto a transparent substrate. Results of interferometric characterization of these plates is described and compared to Kolmolgorov statistics. These plates have been successfully used in the Multi-Conjugate Adaptive Optics (MCAO) testbed and as part of the Villages (Visible Light Laser Guidestar Experiments) calibration system.

MAORY, the Multi-conjugated Adaptive Optics RelaY for the European Extremely Large Telescope, will be located on one of the Nasmyth platforms of the telescope to provide multi conjugated adaptive optics correction of the wavefront. The scientific instruments fed by the module will benefit from a corrected field of view of 2 arcmin diameter with high performance uniformity across the field. The two post-focal deformable mirrors are projected at high altitude by the optical system based on 5 mirrors and one dichroic which splits the laser light of the artificial reference stars from the science channel. The third deformable mirror, conjugated to the ground, is integrated into the telescope. Six laser guide stars are foreseen in order to measure the wavefront distortions and three natural guide stars are used to solve the tip-tilt indetermination problem. The natural guide stars wavefront sensors are located close to the output focal plane in order to minimize the non common path aberrations. Two output ports are foreseen: one gravity invariant located below the optical bench and one on one side of the bench to feed large instruments placed on the Nasmyth platform.

Effective calibration procedures play an important role for the efficiency and performance of astronomical instrumentation. We report on the calibration scheme for ARGOS, the Laser Guide Star (LGS) facility at the LBT. An artificial light source is used to feign the real laser beacons and perform extensive testing of the system, independent of the time of day and weather conditions, thereby greatly enhancing the time available for engineering. Fibre optics and computer generated holograms (CGHs) are used to generate the necessary wavefront. We present the optomechanical design, and discuss the expected accuracy, as well as tolerances in assembly and alignment.

Solar observations are performed over an extended field of view and the isoplanatic patch over which conventional adaptive optics (AO) provides diffraction limited resolution is a severe limitation. The development of multi-conjugate adaptive optics (MCAO) for the next generation large aperture solar telescopes is thus a top priority. The Sun is an ideal object for the development of MCAO since solar structure provides multiple "guide stars" in any desired configuration. At the Dunn Solar Telescope (DST) we implemented a dedicated MCAO bench with the goal of developing wellcharacterized, operational MCAO. The MCAO system uses two deformable mirrors conjugated to the telescope entrance pupil and a layer in the upper atmosphere, respectively. The high altitude deformable mirror can be placed at conjugates ranging from 2km to 10km altitude. We have successfully and stably locked the MCAO system on solar granulation and demonstrated the MCAO system's ability to significantly extend the corrected field of view. We present results derived from analysis of imagery taken simultaneously with conventional AO and MCAO. We also present first results from solar Ground Layer AO (GLAO) experiments.