Search

MAORY is one of the approved instruments for the European Extremely Large Telescope. It is an adaptive optics module, enabling high-angular resolution observations in the near infrared by real-time compensation of the wavefront distortions due to atmospheric turbulence and other disturbances such as wind action on the telescope. An overview of the instrument design is given in this paper.

The success of the next generation of instruments for 20m plus class optical telescopes will depend upon improving the image quality by exploiting sophisticated Adaptive Optics (AO) systems. For several years now, ESO has been very active in gathering requirements, planning, and developing detectors and controllers/cameras for the AO systems of the telescope and instruments of the ELT. From these requirements, the need for three different types of cameras have been identified: 1) ALICE (smALl vIsible CamEra) for Truth/High Order Natural Guide Star (NGS)/Telescope Guiding which uses the “sub-electron RON” Teledyne-e2v CCD220-DD of 240x240 of 24μm pixels; 2) LISA (Large vISble cAmera) for Shack-Hartmann Laser Guide Star (LGS)/Telescope Wavefront Sensing (WFS) which uses the Teledyne-e2v LVSM of 800x800 of 24μm pixels; 3) SAPHIRA Standalone Camera for Low-/High-Order NGS WFS/Fine Centering which uses the Leonardo SAPHIRA of 320x256 of 24μm pixels. This paper provides an update on the development of these cameras and their detectors. For ALICE and LISA, a single camera design approach is being followed with the only difference being the customizable front-ends to support the different type of detector. ALICE and LISA are being built around a common set of components and will look essentially identical from the exterior. COTS modules are being used wherever possible and practical to reduce the development effort and time, and improve functionality and maintainability. A description of the design approach, the common components and the detector specific front-ends will be presented. The LISA camera detector, the LVSM, is under development by Teledyne-e2v. A brief update on the progress of this development will be provided. For the SAPHIRA standalone camera, a different approach is being followed to that of ALICE and LISA. C-RED ONE cameras are being procured from FLI and will be modified by ESO to comply with ELT standards: 10GbE interfaces to the Real Time Computer (RTC) and NGC control computer, and Precision Time Protocol (PTP). PTP is the time reference system of the ELT and will be used by the cameras to schedule and time stamp frames and for synchronizing with other cameras or hardware devices.

The construction of a diffraction limitable telescope as large as the ESO’s ELT is enabled by its embedded deformable quaternary mirror. Besides its essential function in the telescope control, M4 also contributes to compensating the free atmosphere aberrations for all post-focal AO applications. The paper presents how the telescope manages M4 to maintain its optical performance while offering to the instruments a clean wavefront interface, supporting the desired AO functionalities. The paper reviews the telescope strategy to derive its wavefront dynamic properties directly from the analysis of the control data collected in science mode, with the goal to minimize the observatory time spent on dedicated wavefront calibration tasks.

The Prefocal Station (PFS) is the last opto-mechanical unit before the telescope focal plane in the Extremely Large Telescope (ELT) optical train. The PFS distributes the telescope optical beam to the Nasmyth and Coude instrument focal stations and it contains all of the sky metrology (imaging and wavefront sensing) that will be used by the active optics of the telescope and to support operations such as phasing the primary mirror (phasing and diagnostic station). It also hosts local metrology that will be used for coarse alignment and maintenance. We present the main results of a concept design study for the Nasmyth A prefocal station.

In this paper we will report on the status of the instrumentation project for the European Southern Observatory's Extremely Large Telescope (ELT). Three instruments are in the construction phase: HARMONI, MICADO and METIS. The multi-conjugate adaptive optics system for MICADO, MAORY, is also under development. Preliminary Design Reviews of all of these systems are planned to be completed by mid-2019. The construction of a laser tomographic module for HARMONI is part of "Phase 2" of the ELT: the design has been advanced to Preliminary Design level in order to define the interface to the HARMONI spectrograph. Preparations for the next instruments have also been proceeding in parallel with the development of these instruments. Conceptual design studies for the multi-object spectrograph MOSAIC, and for the high resolution spectrograph HIRES have been completed and reviewed. We present the current design of each of these instruments and will summarise the work ongoing at ESO related to their development.

A suite of seven instruments and associated AO systems have been planned as the "E-ELT Instrumentation Roadmap". Following the E-ELT project approval in December 2014, rapid progress has been made in organising and signing the agreements for construction with European universities and institutes. Three instruments (HARMONI, MICADO and METIS) and one MCAO module (MAORY) have now been approved for construction. In addition, Phase-A studies have begun for the next two instruments - a multi-object spectrograph and high-resolution spectrograph. Technology development is also ongoing in preparation for the final instrument in the roadmap, the planetary camera and spectrograph. We present a summary of the status and capabilities of this first set of instruments for the E-ELT.

We study the impact of various telescope effects (like effect of phasing errors, missing segments, etc) on the performance of SCAO systems. This paper is using the E-ELT with 798 primary mirror segments. For example, we will show what kind of AO system (number of sub-apertures, frame-rate) is necessary to compensate for these effects, to get a fully seeing limited performance from the telescope.

Ground-based near-IR imagers assisted by Multi Conjugate Adaptive Optics (MCAO) systems are the technological frontier to obtain high-quality stellar photometry in crowded fields at the highest possible spatial resolution. The Gemini MCAO System (GeMS) feeding the Gemini South Adaptive Optics Imager (GSAOI) is the only facility of this kind currently available to the Community. We used a set of images obtained in the J and Ks bands of the central regions of two Galactic bulge globular clusters (Liller 1 and NGC 6624) with GeMS/GSAOI, under significantly different atmospheric conditions. We characterized the performances of the system in terms of efficiency and uniformity of the Point Spread Function (PSF) over the field of view with varying seeing, airmass and tip-tilt star asterisms. We also compared the PSF performances of GeMS/GSAOI with the HST/ACS ones in the F606W and F814W bands.

The Nasmyth platforms of the E-ELT will contain one Prefocal Station (PFS) each. The main PFS functional requirements are to provide a focal plane to the three Nasmyth focal stations and the Coude focus, optical sensing supporting telescope low order optimisation and seeing limited image quality, and optical sensing supporting characterising and phasing of M1 and other telescope subsystems. The PFS user requirements are used to derive the PFS technical requirements specification that will form the basis for design, development and production of the system. This specification process includes high-level architectural decisions and technical performance budget allocations. The mechanical design concepts reported here have been developed in order to validate key system specifications and associated technical budgets.

ESO has a very active on-going AO WFS detector development program to not only meet the needs of the current crop of instruments for the VLT, but also has been actively involved in gathering requirements, planning, and developing detectors and controllers/cameras for the instruments in design and being proposed for the E-ELT. This paper provides an overall summary of the AO WFS Detector requirements of the E-ELT instruments currently in design and telescope focal units. This is followed by a description of the many interesting detector, controller, and camera developments underway at ESO to meet these needs; a) the rationale behind and plan to upgrade the 240x240 pixels, 2000fps, “zero noise”, L3Vision CCD220 sensor based AONGC camera; b) status of the LGSD/NGSD High QE, 3e- RoN, fast 700fps, 1760x1680 pixels, Visible CMOS Imager and camera development; c) status of and development plans for the Selex SAPHIRA NIR eAPD and controller. Most of the instruments and detector/camera developments are described in more detail in other papers at this conference.

In this paper, we present an algorithm and supporting simulations results showing how a single conjugated AO system can be used to detect a scalloping error occurring in the telescope. We show that when the scalloping error modes are entered in the reconstruction modal basis, the Deformable Mirror shape can be used to estimate the scalloping error through a simple matrix vector multiply. Temporal averaging allows to get rid of the atmospheric noise on the scalloping measurement assuming a perfect “scalloping actuator” and to get a measurement accuracy of about 20nm rms.

The Multi-Conjugate Adaptive Optics module for the European Extremely Large Telescope has been designed to achieve uniform compensation of the atmospheric turbulence effects on a wide field of view in the near infrared. The design realized in the Phase A of the project is undergoing major revision in order to define a robust baseline in view of the next phases of the project. An overview of the on-going activities is presented.

In this paper, modern subspace identification methods are applied to a Multi-conjugate Adaptive optics Demonstrator, MAD, developed at ESO. The identified multi-input multi-output systems mapping voltages into slopes can be obtained on data taken in open/closed loop on beacon and in both SCAO and GLAO configurations. The advantages of the proposed approach is twofold: on the one hand the experiment to collect the data takes only few minutes during day time, it can be done on beacon, and all the computational effort is moved off-line. On the other hand, subspace identification provides the mathematical model necessary to design modern model-based controllers (e.g. linear quadratic control).

The New Adaptive Optics Module for Interferometry (NAOMI)1 is the future low order adaptive optics system to be developed for and installed at the ESO 1.8 m Auxiliary Telescopes (ATs). The four ATs2 are designed for interferometry which they are essentially dedicated for. Currently the AT’s are equipped with a fast, visible tip-tilt sensor called STRAP3 (System for Tip/tilt Removal with Avalanche Photodiodes), and the corrections are applied through a tip-tilt mirror. The goal is to equip all four ATs with a low-order Shack-Hartmann system operating in the visible for the VLTI dual feed light beams in place of the current tip-tilt correction. Because of the limited size of the ATs (1.8m diameter), a low-order system will be sufficient. The goal is to concentrate the energy into a coherent core and to make the encircled energy (into the single mode fibers) stable and less dependent on the atmospheric conditions in order to increase the sensitivity of the interferometric instruments. The system will use the ESO real time computer platform Sparta-light as the baseline. This paper presents the preliminary design concept and outlines the benefits to current and future VLTI instruments.

The Enhanced Resolution Imager and Spectrograph (ERIS) is the new Adaptive Optics based instrument for ESO’s VLT aiming at replacing NACO and SINFONI to form a single compact facility with AO fed imaging and integral field unit spectroscopic scientific channels. ERIS completes the instrument suite at the VLT adaptive telescope. In particular it is equipped with a versatile AO system that delivers up to 95% Strehl correction in K band for science observations up to 5 micron It comprises high order NGS and LGS correction enabling the observation from exoplanets to distant galaxies with a large sky coverage thanks to the coupling of the LGS WFS with the high sensitivity of its visible WFS and the capability to observe in dust embedded environment thanks to its IR low order WFS. ERIS will be installed at the Cassegrain focus of the VLT unit hosting the Adaptive Optics Facility (AOF). The wavefront correction is provided by the AOF deformable secondary mirror while the Laser Guide Star is provided by one of the four launch units of the 4 Laser Guide Star Facility for the AOF. The overall layout of the ERIS AO system is extremely compact and highly optimized: the SPIFFI spectrograph is fed directly by the Cassegrain focus and both the NIX’s (IR imager) and SPIFFI’s entrance windows work as visible/infrared dichroics. In this paper we describe the concept of the ERIS AO system in detail, starting from the requirements and going through the estimated performance, the opto-mechanical design and the Real-Time Computer design.

The New Adaptive Optics Module for Interferometry (NAOMI) is the future low order Adaptive optics system to be developed for and installed at the ESO 1.8 m Auxiliary Telescopes (ATs). The four ATs are designed for interferometry which they are essentially dedicated for. The project goal is to equip the telescopes with a low-order Shack-Hartmann system operating in the visible in place of the current tip-tilt correction. The deformable mirror (DM) for NAOMI is rotating with the AT azimuth axis whereas the wavefront sensor (WFS), which signals are used to control the DM, has a fixed position in the telescope basement. It is not co-rotating with the DM. The result is that the projection of the actuator pattern is rotating with respect to the WFS when the telescope is tracking an object on sky. In order to avoid the use of an optical de-rotator we developed an algorithm to de-rotate the commands to the DM in software. This paper outlines the concept of the software de-rotation as well as the performance obtained from end-to-end simulations.

ERIS is the new Single Conjugate Adaptive Optics (AO) instrument for VLT in construction at ESO with the collaboration of Max-Planck Institut fuer Extraterrestrische Physik, ETH-Institute for Astronomy and INAF - Osservatorio Astrofisico di Arcetri. The ERIS AO system relies on a 40×40 sub-aperture Pyramid Wavefront Sensor (PWFS) for two operating modes: a pure Natural Guide Star high-order sensing for high Strehl and contrast correction and a low-order visible sensing in support of the Laser Guide Star AO mode. In this paper we present in detail the preliminary design of the ERIS PWFS that is developed under the responsibility of INAF-Osservatorio Astrofisico di Arcetri in collaboration with ESO.

The Enhanced Resolution Imager and Spectrograph (ERIS) is the next-generation adaptive optics near-IR imager and spectrograph for the Cassegrain focus of the Very Large Telescope (VLT) Unit Telescope 4, which will soon make full use of the Adaptive Optics Facility (AOF). It is a high-Strehl AO-assisted instrument that will use the Deformable Secondary Mirror (DSM) and the new Laser Guide Star Facility (4LGSF). The project has been approved for construction and has entered its preliminary design phase. ERIS will be constructed in a collaboration including the MaxPlanck Institut fur Extraterrestrische Physik, the Eidgenossische Technische Hochschule Zurich and the Osservatorio Astrofisico di Arcetri and will offer 1 – 5 μm imaging and 1 – 2.5 μm integral field spectroscopic capabilities with a high Strehl performance. Wavefront sensing can be carried out with an optical high-order NGS Pyramid wavefront sensor, or with a single laser in either an optical low-order NGS mode, or with a near-IR low-order mode sensor. Due to its highly sensitive visible wavefront sensor, and separate near-IR low-order mode, ERIS provides a large sky coverage with its 1’ patrol field radius that can even include AO stars embedded in dust-enshrouded environments. As such it will replace, with a much improved single conjugated AO correction, the most scientifically important imaging modes offered by NACO (diffraction limited imaging in the J to M bands, Sparse Aperture Masking and Apodizing Phase Plate (APP) coronagraphy) and the integral field spectroscopy modes of SINFONI, whose instrumental module, SPIFFI, will be upgraded and re-used in ERIS. As part of the SPIFFI upgrade a new higher resolution grating and a science detector replacement are envisaged, as well as PLC driven motors. To accommodate ERIS at the Cassegrain focus, an extension of the telescope back focal length is required, with modifications of the guider arm assembly. In this paper we report on the status of the baseline design. We will also report on the main science goals of the instrument, ranging from exoplanet detection and characterization to high redshift galaxy observations. We will also briefly describe the SINFONI-SPIFFI upgrade strategy, which is part of the ERIS development plan and the overall project timeline.

The Enhanced Resolution Imager and Spectrograph (ERIS) is the next-generation instrument planned for the Very Large Telescope (VLT) and the Adaptive Optics Facility (AOF) 1 . It is an AO assisted instrument that will make use of the Deformable Secondary Mirror and the new Laser Guide Star Facility (4LGSF), and it is designed for the Cassegrain focus of the telescope UT4. The project just concluded its conceptual design phase and is awaiting formal approval to continue to the next phase. ERIS will offer 1-5 μm imaging and 1-2.5 μm integral field spectroscopic capabilities with high Strehl performance. As such it will replace, with much improved single conjugated AO correction, the most scientifically important and popular observing capabilities currently offered by NACO 2 (diffraction limited imaging in JM band, Sparse Aperture Masking and APP coronagraphy) and by SINFONI 3 , whose instrumental module, SPIFFI, will be re-used in ERIS. The Cassegrain location and the performance requirements impose challenging demands on the project, from opto-mechanical design to cryogenics to the operational concept. In this paper we describe the baseline design proposed for ERIS and discuss these technical challenges, with particular emphasis on the trade-offs and the novel solutions proposed for building ERIS.

The Enhanced Resolution Imager and Spectrograph (ERIS) is the next-generation instrument planned for the Very Large Telescope (VLT) and the Adaptive Optics facility (AOF). It is an AO assisted instrument that will make use of the Deformable Secondary Mirror and the new Laser Guide Star Facility (4LGSF), and it is planned for the Cassegrain focus of the telescope UT4. The project is currently in its Phase A awaiting for approval to continue to the next phases. The Adaptive Optics system of ERIS will include two wavefront sensors (WFS) to maximize the coverage of the proposed sciences cases. The first is a high order 40x40 Pyramid WFS (PWFS) for on axis Natural Guide Star (NGS) observations. The second is a high order 40x40 Shack-Hartmann WFS for single Laser Guide Stars (LGS) observations. The PWFS, with appropriate sub-aperture binning, will serve also as low order NGS WFS in support to the LGS mode with a field of view patrolling capability of 2 arcmin diameter. Both WFSs will be equipped with the very low read-out noise CCD220 based camera developed for the AOF. The real-time reconstruction and control is provided by a SPARTA real-time platform adapted to support both WFS modes. In this paper we will present the ERIS AO system in all its main aspects: opto-mechanical design, real-time computer design, control and calibrations strategy. Particular emphasis will be given to the system performance obtained via dedicated numerical simulations.

ESO's Multi-conjugate Adaptive-optics Demonstrator (MAD) was a prototype designed and built to demonstrate wide-field adaptive optics science on large telescopes. The outstanding results obtained during commissioning and guaranteed time observations (GTO) prompted ESO to issue and open call to the community for 23 science demonstration (SD) observing nights distributed in three runs (in order to provide access to the summer an winter skies). Thus, in total MAD was used for science for 33 nights including the 10 nights of GTO time. date, 19 articles in refereed journals (including one in Nature) have been published based fully or partially o MAD data. To the best of our knowledge, these are not only the first, but also the only scientific publication from MCAO instruments world-wide to date (at least in Astronomy). The scientific impact of these publication, as measured by the h-index, is comparable to that of other AO instruments on the VLT, although over the years these instruments have been allocated many more nights than MAD. In this contribution we present an overview of the scientific results from MAD and a more detailed discussion of the most cited papers. © (2012) COPYRIGHT Society of Photo-Optical Instrumentation Engineers (SPIE). Downloading of the abstract is permitted for personal use only.

The AO system calibration is usually done with a dedicated setup during daytime. Here we present results of two alternative techniques as the synthetic and the on-sky interaction matrix calibration. In both cases we created matrices controlling 400 modes of the LBT-FLAO system. We present here the performances reached on-sky at LBT compared with those obtained with the standard calibration. The described techniques allow calibrating the AO system without any dedicated hardware. This is particularly attractive for systems that require complex calibration setup such as those with a convex adaptive secondary like the MMT and the planned VLT AOF.

This PDF file contains the front matter associated with SPIE Proceedings Volume 8447, including the Title Page, Copyright information, Table of Contents, and Conference Committee listing. © (2012) COPYRIGHT Society of Photo-Optical Instrumentation Engineers (SPIE). Downloading of the abstract is permitted for personal use only.

This paper presents the performance analysis based on numerical simulations of the Pyramid Wavefront sensor Module (PWM) to be included in ERIS, the new Adaptive Optics (AO) instrument for the Adaptive Optics Facility (AOF). We have analyzed the performance of the PWM working either in a low-order or in a high-order wavefront sensing mode of operation. We show that the PWM in the high-order sensing mode can provide SR > 90% in K band using bright guide stars under median seeing conditions (0.85 arcsec seeing and 15 m/s of wind speed). In the low-order sensing mode, the PWM can sense and correct Tip-Tilt (and if requested also Focus mode) with the precision required to assist the LGS observations to get an SR > 60% and > 20% in K band, using up to a ~16.5 and ~19.5 R-magnitude guide star, respectively.

The current baseline for the Multi-Conjugate adaptive optics module (MAORY) for the European Extremely Large Telescope is based on the Sodium Laser Guide Stars (LGS) approach, in order to ensure correction uniformity and sky coverage. However, since the Sodium layer is approximately 10 km thick, the artificial reference source looks elongated, especially when observed from the edge of a large aperture, with elongation depending on the actual telescope diameter, on the Sodium layer properties and on the laser launcher position. We studied numerically, by means of simulations, the performance of three different algorithms for the instantaneous LGS image position measurement in presence of elongated spots: the Weighted Center of Gravity, the Correlation and the Quad-cell. Since all the three considered algorithms require some sort of 'reference', the problem of the temporal variation of the Sodium Layer properties has to be addressed. Another important aspect that has be addressed in the analysis is the impact of the low-order aberrations introduced by the MAORY re-imaging optics, by the Sodium Density profile shape and by its projection in the LGS image plane. An LGS wavefront sensor laboratory prototype was designed to reproduce the relevant aspects of a Shack-Hartmann wavefront Sensor for the European Extremely Large Telescope and, through laboratory tests, to evaluate the performance of different centroid algorithms in presence of elongated spots, with realistic Sodium profiles, as previously investigated numerically and analytically, analyzing the impact of the low-order aberrations and of relevant WFS parameters, like signal-to-noise ratio, sampling and subaperture size. This paper shows the results of the tests performed with this prototype.

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.

As of 2013, the ESO's VLT will be equipped with the Adaptive Optics Facility for Ground Layer and Laser Tomography adaptive optics assisted imaging and spectroscopy, using a Deformable Secondary Mirror and four Laser Guide Stars. Following the successful experience of the MAD demonstrator, we initiated a speculative study to evaluate the performance gain obtained by implementing a type of Multi-Conjugate Adaptive Optics correction that benefits from the unique features provided by the AOF. In this paper we present the basic concept and provide a first estimation of the correction performance obtained in the near infrared.

In this paper we present a brief status report on the conceptual designs of the instruments and adaptive optics modules that have been studied for the European Extremely Large Telescope (E-ELT). In parallel with the design study for the 42-m telescope, ESO launched 8 studies devoted to the proposed instruments and 2 for post-focal adaptive optics systems. The studies were carried out in consortia of ESO member state institutes or, in two cases, by ESO in collaboration with external institutes. All studies have now been successfully completed. The result is a powerful set of facility instruments which promise to deliver the scientific goals of the telescope. The aims of the individual studies were broad: to explore the scientific capabilities required to meet the E-ELT science goals, to examine the technical feasibility of the instrument, to understand the requirements placed on the telescope design and to develop a delivery plan. From the perspective of the observatory, these are key inputs to the development of the proposal for the first generation E-ELT instrument suite along with the highest priority science goals and budgetary and technical constraints. We discuss the lessons learned and some of the key results of the process.

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.

Simulations of adaptive optics (AO) for the European extremely large telescope (EELT) are presented. For Shack-Hartmann wavefront sensors for the laser guide star (LGS) based systems, the simulations show that without the Rayleigh fratricide effect, central projection of the laser is preferable to side projection, the correlation or matched filter centroiding algorithms offer superior performance to a traditional center-of-gravity approach, the optimum sampling of the detector is approximately 1.5 pixels per FWHM of the non-elongated spot, and that at least 10×10 pixels are required. The required number of photo-detection events from the LGS per frame per subaperture is of the order of 1000. Correction of segmentation errors with a Shack-Hartmann wavefront sensor (WFS) has also been investigated; atmospheric turbulence dominates these segmentation errors. The pyramid WFS is also simulated for the EELT, showing that modulation of the pyramid will be necessary.

MAORY, the multi-conjugate adaptive optics module for the E-ELT, is supposed to be placed in one of the two Nasmyth platforms of the telescope, re-imaging the focal plane with a diffraction limited image quality. The requested operating wavelength is from 0.6 to 2.4μm with a high throughput. The module will include a natural guide stars wave front sensor (NGS WFS) and a laser guide stars WFS (LGS WFS) and will feed at least two scientific instruments with a corrected field of view up to 2 arcmin, providing a mechanical de-rotation for the light instruments attached (< 4tons). We present below a preliminary optical design of the post focal relay taking count of the required performance. A particular attention is paid to the critical aspects such as the pupil de-rotation, the light splitting between the WFSs and the scientific channel and the deformable mirrors (DMs) optical parameters and dimensioning.

In the last years an increasing consideration has been given to the study of Laser Guide Stars (LGS) for the measurement of the disturbance introduced by the atmosphere. Due to the finite distance of the artificial reference source and its vertical extension (the Sodium layer occurs at approximately 90 km, with a vertical thickness of about 10 km), the source itself looks elongated, when observed from the edge of a large aperture. On a 40 m class telescope, for instance, the maximum elongation varies between 4 and 6 arcseconds, depending on the Sodium layer properties and on the launching position. This spot elongation strongly limits the performance of the most common wavefront sensors. A straightforward solution for a Shack-Hartmann wavefront sensor is to increase the laser power, in order to balance the loss of centroiding accuracy due to the elongation. This solution, although appealing in principle, presents drawbacks related, for instance, to the availability of very powerful lasers. We propose in this paper a wavefront sensor concept that provides an optical solution to the perspective elongation problem. It is based on an array of bi-prisms placed in the focal plane of a lenslet array; each bi-prism is aligned to the elongated spot produced by the corresponding lenslet; the spot is split into two beams, that are re-imaged into two micro-images of the sub-aperture itself; the difference in the integrated intensity of these two micro-images is proportional to the local wavefront slope. This method is sensitive only to the slope information in the direction locally orthogonal to the bi-prisms (and to the elongation) and the full information has to be recovered by combining the signals coming from different LGSs launched from different positions at the telescope edge. The pros and cons of this technique, in terms of hardware requirements and photon budget, are discussed in this paper.

The multi-conjugate adaptive optics module for the European Extremely Large Telescope has to provide a corrected field of medium to large size (up to 2 arcmin), over the baseline wavelength range 0.8-2.4 µm. The current design is characterized by two post-focal deformable mirrors, that complement the correction provided by the adaptive telescope; the wavefront sensing is performed by means of a high-order multiple laser guide star wavefront sensor and by a loworder natural guide star wavefront sensor. The present status of a two years study for the advanced conceptual design of this module is reported.

The Multi-Conjugate Adaptive Optics Demonstrator (MAD) built by ESO with the contribution of two external consortia is a powerful test bench for proving the feasibility of Multi-Conjugate (MCAO) and Ground Layer Adaptive Optics (GLAO) techniques both in the laboratory and on the sky. MAD is based on a two deformable mirrors correction system and on two multi-reference wavefront sensors (Star Oriented and Layer Oriented) capable to observe simultaneously some pre-selected configurations of Natural Guide Stars. MAD corrects up to 2 arcmin field of view in K band. After a long laboratory test phase, it has been installed at the VLT and it successfully performed on-sky demonstration runs on several astronomical targets for evaluating the correction performance under different atmospheric turbulence conditions. In this paper we present the results obtained on the sky in Star Oriented mode for MCAO and GLAO configurations and we correlate them with different atmospheric turbulence parameters. Finally we compare some of the on-sky results with numerical simulations including real turbulence profile measured at the moment of the observations.

ONIRICA, standing for OWL Near InfraRed Imaging Camera, is a pre-Phase A, conceptual design study to assess the feasibility of an imaging camera for a 100m class telescope. In this paper the main scientific driven and the adopted preliminary choices for its optomechanical implementation are reviewed.

The Multi-Conjugate Adaptive Optics Demonstrator (MAD) built by ESO with the contribution of two external consortia is a powerful test bench for proving the feasibility of Ground Layer (GLAO) and Multi-Conjugate Adaptive Optics (MCAO) techniques both in the laboratory and on the sky. The MAD module will be installed at one of the VLT unit telescope in Paranal observatory to perform on-sky observations. MAD is based on a two deformable mirrors correction system and on two multi-reference wavefront sensors (Star Oriented and Layer Oriented) capable to observe simultaneously some pre-selected configurations of Natural Guide Stars. MAD is expected to correct up to 2 arcmin field of view in K band. MAD is completing the test phase in the Star Oriented mode based on Shack-Hartmann wavefront sensing. The GLAO and MCAO loops have been successfully closed on simulated atmosphere after a long phase of careful system characterization and calibration. In this paper we present the results obtained in laboratory for GLAO and MCAO corrections testing with bright guide star flux in Star Oriented mode paying also attention to the aspects involving the calibration of such a system. A short overview of the MAD system is also given.

MAD5 is a Multi-Conjugate Adaptive Optics (MCAO) system conceived to demonstrate the feasibility of MCAO on the sky. The wave front sensor part is divided in two channels: a Shack-Hartmann sensor and a Layer Oriented sensor. We will describe the construction of the latter one. Assembly, integration and test of the instrument are the first steps for ESO acceptance, before integrating the Layer Oriented sensor with the other components of MAD. We will show qualitative and quantitative results of optical and mechanical tests: in particular we will describe the alignment of the references selection unit, constituted by sixteen motorized linear positioners and eight star enlargers, of the beam compressor and of the two re-imaging objectives, each one conjugated to a different altitude. Being the pyramid the core of this kind of wave front sensor, we will focus our attention on its construction difficulties and we will discuss all the optical tests made to choose the best ones to be installed on the wave front sensor. Finally we will present the sensor performance showing the first open loop results.

The ESO Multi-conjugate Adaptive optics Demonstrator (MAD) is a prototype intended to be tested at the VLT Nasmyth focus. With its development raises the problem of calibration of an AO system composed of several correcting devices and wave front sensors. One part of this process is the calibration of the static aberrations of the system, always present in spite of the best efforts made during the design, the manufacturing of the optics and their alignment. In this paper we present a study to find an optimized way to correct for the static aberrations in the scientific FoV of an MCAO system. Thanks to images from the camera, the WF error in the FoV is computed, the contribution of several altitudes reconstructed, and finally projected on the deformable mirrors in order to compensate for the measured aberrations. This technique, inspired from the calibration of the static aberration of the system NAOS-CONICA, allows bringing the best quality to the scientific instrument fed by an MCAO system, by taking the most of the presence of correcting devices in the optical path.

The Multi-Atmospheric Phase screens and Stars (MAPS) instrument is a powerful tool that has been developed in the framework of the ESO Multi-conjugate Adaptive optics Demonstrator project (MAD). It allows emulating a 3D evolving Paranal-like atmosphere as well as up to 12 sources in a 2 arc minutes field of view, as seen at a Nasmyth focus of one of the VLT. It will be used to perform advanced laboratory tests on MAD before its shipment to Chile. In this paper we present the opto-mechanical design of MAPS. This one simulates the characteristics of the VLT focus and achieves a high Strehl Ratio over the whole Field of View in the visible as well as in the infrared. A curved entrance plate crowded with fibers emulates various stars configurations including real sky asterisms. In order to simulate the atmosphere, three rotating Phase Screens are placed in the beam and conjugated with different altitudes. Those are glass plates dig in their surface in a way that the beam passing through is distorted as it would be by an atmospheric turbulent layer. In this poster we also present the process of research that lead to the choice of a reliable technique to imprint the aberrations into the screens, their properties and expected performance.

The controller is one of the essential components of a multi-conjugate adaptive optics (MCAO) system. We present in this paper a preliminary comparison in performance based on numerical simulations of two simple control laws for a star-oriented MCAO configuration. The first control law is based on a TSVD reconstruction matrix and a constant-gain integrator, and the second one is based on an optimized modal gain integrator. These control laws will be validated experimentally with the Multi-conjugate Adaptive Optics Demonstrator (MAD).

The European Southern Observatory together with external research Institutes is building a Multi-Conjugate Adaptive Optics Demonstrator (MAD) to perform wide field of view adaptive optics correction. The aim of MAD is to demonstrate on the sky the feasibility of the MCAO technique and to evaluate all the critical aspects in building such kind of instrument in the framework of both the 2nd generation VLT instrumentation and the 100-m Overwhelmingly Large Telescope (OWL). The MAD module will be installed at one of the VLT unit telescope in Paranal to perform on-sky observations. MAD is based on a two deformable mirrors correction system and on two multi-reference wavefront sensors capable to observe simultaneously some pre-selected configurations of Natural Guide Stars. MAD is expected to correct up to 2 arcmin field of view in K band. MAD has just started the integration phase which will be followed up by a long period of testing. In this paper we present the final design of MAD with a brief report about the status of the integration.

The CAMCAO instrument is a high resolution near infrared (NIR) camera conceived to operate together with the new ESO Multi-conjugate Adaptive optics Demonstrator (MAD) with the goal of evaluating the feasibility of Multi-Conjugate Adaptive Optics techniques (MCAO) on the sky. It is a high-resolution wide field of view (FoV) camera that is optimized to use the extended correction of the atmospheric turbulence provided by MCAO. While the first purpose of this camera is the sky observation, in the MAD setup, to validate the MCAO technology, in a second phase, the CAMCAO camera is planned to attach directly to the VLT for scientific astrophysical studies. The camera is based on the 2kx2k HAWAII2 infrared detector controlled by an ESO external IRACE system and includes standard IR band filters mounted on a positional filter wheel. The CAMCAO design requires that the optical components and the IR detector should be kept at low temperatures in order to avoid emitting radiation and lower detector noise in the region analysis. The cryogenic system inclues a LN2 tank and a sptially developed pulse tube cryocooler. Field and pupil cold stops are implemented to reduce the infrared background and the stray-light. The CAMCAO optics provide diffraction limited performance down to J Band, but the detector sampling fulfills the Nyquist criterion for the K band (2.2mm).

Layer Oriented represented in the last few years a new and promising aproach to solve the problems related to the limited field of view achieved by classical Adaptive Optics systems. It is basically a different approach to multi conjugate adaptive optics, in which pupil plane wavefront sensors (like the pyramid one) are conjugated to the same altitudes as the deformable mirrors. Each wavefront sensor is independently driving its conjugated deformable mirror thus simplifying strongly the complexity of the wavefront computers used to reconstruct the deformations and drive the mirror themselves, fact that can become very important in the case of extremely large telescopes where the complexity is a serious issue. The fact of using pupil plane wavefront sensors allow for optical co-addition of the light at the level of the detector thus increasing the SNR of the system and permitting the usage of faint stars, improving the efficiency of the wavefront sensor. Furthermore if coupled to the Pyramid wavefront sensor (because of its high sensitivity), this technique is actually peforming a very efficient usage of the light leading to the expectation that, even by using only natural guide stars, a good sky coverage can be achieved, above all in the case of giant telescopes. These are the main reasons for which in the last two years several projects decided to make MCAO systems based on the Layer Oriented technique. This is the case of MAD (an MCAO demonstrator that ESO is building with one wavefront sensing channel based on the Layer Oriented concept) and NIRVANA (an instrument for LBT). Few months ago we built and successfully tested a first prototype of a layer oriented wavefront sensor and experiments and demonstrations on the sky are foreseen even before the effective first light of the above mentioned instruments. The current situation of all these projects is presented, including the extensive laboratory testing and the on-going experiments on the sky.

Over the past two years ESO has reinforced its efforts in the field of Adaptive Optics. The AO team has currently the challenging objectives to provide 8 Adaptive Optics systems for the VLT in the coming years and has now a world-leading role in that field. This paper will review all AO projects and plans. We will present an overview of the Nasmyth Adaptive Optics System (NAOS) with its infrared imager CONICA installed successfully at the VLT last year. Sodium Laser Guide Star plans will be introduced. The status of the 4 curvature AO systems (MACAO) developed for the VLT interferometer will be discussed. The status of the SINFONI AO module developed to feed the infrared integral field spectrograph (SPIFFI) will be presented. A short description of the Multi-conjugate Adaptive optics Demonstrator MAD and its instrumentation will be introduced. Finally, we will present the plans for the VLT second-generation AO systems and the researches performed in the frame of OWL.

The Adaptive Optics for the Telescopio Nazionale Galileo module (namely AdOpt@TNG) implements the pyramid wavefront sensor as a unique feature. This allows to get valuable information on its performance on the sky. An updated overview of the results obtained so far is shown, including a discussion on the sources of errors in the closed loop operation, distinguishing them between the ones specific of the pyramid wavefront sensor and the one more related to the system as a whole. This system allows also for a number of experiments and check of the sensitivity of such a wavefront sensor, especially in comparison with other types of sensing units. The ways to accomplish such an experiment in a convincing way are shown along with the first results obtained so far. Finally, we describe how and up to which extent a number of practical problems encountered in the near past can be solved implementing the recent new ideas on the pyramid theme, many of which popped up from our "lessons learned".

Layer Oriented MCAO is a promising technique attempting to perform wide field of view correction with Natural Guide Stars. In the extended concept of Multiple Field of View Layer Oriented MCAO the wavefront sensor field of view is enlarged to collect more photons from more Natural Guide Stars and, in principle, significant sky coverages at any galactic latitude are achieved using only Natural Guide Stars. In this paper we address the problem of finding the best magnitude range for the Natural Guide Stars in order to achieve the best correction with the largest sky coverage in the Layer Oriented Multiple Field of View. For a given Field of View and sky direction we consider only the Natural Guide Stars within a given brightness range and we compute the equivalent integrated magnitude. Then we correlate the contribution in sky coverage of the previously considered Natural Guide Stars and we extrapolate which is the magnitude class giving the largest sky coverage. Once identified the more suitable Natural Guide Star magnitude class we discuss the possible implications in the design of a Multiple Field of View Layer Oriented wavefront sensor and we give the order of magnitude for the main parameters, i.e., maximum number of Natural Guide Stars and detector characteristics.

A demonstrator of the multi-conjugate adaptive optics concept is under construction at ESO and will be installed on the Nasmyth focus of the VLT. This demonstrator called MAD will have two different wavefront sensor channels: Shack-Hartmann and Layer-Oriented; in this article we only describe the Layer-Oriented one. The Layer-Oriented wavefront sensor can select eight reference stars in the two arc-minutes corrected field of view in order to have a maximum of two references in each quarter of the field. XY stages will remotely adjust the position of each reference star selector. The starlight will be fed onto two detectors and two completely independent loops will drive the deformable mirrors, one conjugated to the ground and the other to an altitude of approximately 8 km. The Layer-Oriented wavefront sensor will use the same CCDs than the Shack-Hartmann channel and the pupil will be divided into 9×9 subapertures both for the high and for the ground layer. The spatial sampling of the subapertures will be different for the two CCDs and their integration time will be tuned to typical values of the conjugated altitudes characteristic wind speed. The overall status of the instrument with respect to optics, mechanics, electronics and software is given hereafter. We also summarize the progress on the procurement phase and give the time schedule for the assembling, integration and testing phases.

In this paper, we review the salient facts for a range of available atmosphere emulation technologies, and in the framework of the ESO Multi-Conjugate-AO demonstrator project, aptly called MAD, we present our phase screen test results for silver-sodium ion-exchange, transmissive phase screens. We find (a) that the measured power spectrum of phase fluctuations is consistent with the input Von Karman spectrum and (b) that by tracking the best focus of ten spots formed by a silver-sodium ion-exchange micro-lens array, it was found that the wavelength dependence of 1.266μm of phase-shift is 1.5±2.5% relative to air in the wavelength range 550nm to 800μm. Additionally, we present our optical design and specifications for MAPS, the Multi-Atmospheric Phase screens and Stars instrument that will be used to test MAD before shipment to the VLT. It includes glass screens conjugate to the 0.25km, 3.0km, and 9.0km atmospheric layers above the telescope. We explain the reasoning behind the choice of pupil size and implications for phase screen proximity, footprint sizes, and wind speed gradients. Our design mimics the VLT Nasmyth F/15 focal plane in terms of plate scale, field of view, high Strehl, and field curvature.