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International audience; The adaptive optics systems of future Extremely Large Telescopes (ELTs) will be assisted with laser guide stars (LGS) which will be created in the sodium layer at a height of ≈90 km above the telescopes. In a Shack–Hartmann wavefront sensor, the long elongation of LGS spots on the sub-pupils far apart from the laser beam axis constraints the design of the wavefront sensor (WFS) which must be able to fully sample the elongated spots without undersampling the non-elongated spots. To fulfill these requirements, a newly released large complementary metal oxide semiconductor sensor with 1100 × 1600 pixels and 9 μm pixel pitch could be employed. Here, we report on the characterization of such a sensor in terms of noise and linearity, and we evaluate its performance for wavefront sensing based on the spot centroid variations. We then illustrate how this new detector can be integrated into a full LGS WFS for both the European Southern Observatory’s ELT and the Thirty Meter Telescope.; Les systèmes d'optique adaptative des futurs Extremely Large Telescopes (ELT) seront assistés par des étoiles guides laser (LGS) qui seront créées dans la couche de sodium à une hauteur de ≈90 km au-dessus des télescopes. Dans un capteur de front d'onde de Shack-Hartmann, la longue élongation des taches LGS sur les sous-pupilles éloignées de l'axe du faisceau laser contraint la conception du capteur de front d'onde (WFS) qui doit être capable d'échantillonner entièrement les taches allongées sans sous-échantillonner les taches non allongées. Pour répondre à ces exigences, un grand capteur à semi-conducteurs d'oxyde de métal complémentaire récemment commercialisé avec 1100 × 1600 pixels et un pas de pixel de 9 μm pourrait être employé. Nous présentons ici la caractérisation d'un tel capteur en termes de bruit et de linéarité, et nous évaluons ses performances pour la détection du front d'onde en fonction des variations du centroïde du spot. Nous illustrons ensuite comment ce nouveau détecteur peut être intégré dans un WFS LGS complet pour l'ELT de l'Observatoire européen austral et le télescope de trente mètres.

Ground-based and airborne instrumentation for astronomy IX (2022), Montreal, JUL 17-22, 2022.--Proceedings of SPIE - The International Society for Optical Engineering vol. 12184 Article number 1218424.-- Complete list of authors: Marconi, A.; Abreu, M.; Adibekyan, V.; Alberti, V.; Albrecht, S.; Alcaniz, J.; Aliverti, M.; Allende Prieto, C.; Gomez, J. D. Alvarado; Amado, P. J.; Amate, M.; Andersen, M. I.; Artigau, E.; Baker, C.; Baldini, V.; Balestra, A.; Barnes, S. A.; Baron, F.; Barros, S. C. C.; Bauer, S. M.; Beaulieu, M.; Bellido-Tirado, O.; Benneke, B.; Bensby, T.; Bergin, E. A.; Biazzo, K.; Bik, A.; Birkby, J. L.; Blind, N.; Boisse, I.; Bolmont, E.; Bonaglia, M.; Bonfils, X.; Borsa, F.; Brandeker, A.; Brandner, W.; Broeg, C. H.; Brogi, M.; Brousseau, D.; Brucalassi, A.; Brynnel, J.; Buchhave, L. A.; Buscher, D. F.; Cabral, A.; Calderone, G.; Calvo-Ortega, R.; Cantalloube, F.; Canto Martins, B. L.; Carbonaro, L.; Chauvin, G.; Chazelas, B.; Cheffot, A. -L.; Cheng, Y. S.; Chiavassa, A.; Christensen, L.; Cirami, R.; Cook, N. J.; Cooke, R. J.; Coretti, I.; Covino, S.; Cowan, N.; Cresci, G.; Cristiani, S.; Cunha Parro, V.; Cupani, G.; D'Odorico, V.; de Castro Leao, I.; De Cia, A.; De Medeiros, J. R.; Debras, F.; Debus, M.; Demangeon, O.; Dessauges-Zavadsky, M.; Di Marcantonio, P.; Dionies, F.; Doyon, R.; Dunn, J.; Ehrenreich, D.; Faria, J. P.; Feruglio, C.; Fisher, M.; Fontana, A.; Fumagalli, M.; Fusco, T.; Fynbo, J.; Gabella, O.; Gaessler, W.; Gallo, E.; Gao, X.; Genolet, L.; Genoni, M.; Giacobbe, P.; Giro, E.; Goncalves, R. S.; Gonzalez, O. A.; Gonzalez Hernandez, J. I.; Gracia Temich, F.; Haehnelt, M. G.; Haniff, C.; Hatzes, A.; Helled, R.; Hoeijmakers, H. J.; Huke, P.; Jaervinen, A. S.; Jaervinen, S. P.; Kaminski, A.; Korn, A. J.; Kouach, D.; Kowzan, G.; Kreidberg, L.; Landoni, M.; Lanotte, A.; Lavail, A.; Li, J.; Liske, J.; Lovis, C.; Lucatello, S.; Lunney, D.; MacIntosh, M. J.; Madhusudhan, N.; Magrini, L.; Maiolino, R.; Malo, L.; Man, A. W. S.; Marquart, T.; Marques, E. L.; Martins, C. J. A. P.; Martins, A. M.; Maslowski, P.; Mason, E.; Mason, C. A.; McCracken, R. A.; Mergo, P.; Micela, G.; Mitchell, T.; Molliere, P.; Monteiro, M. A.; Montgomery, D.; Mordasini, C.; Morin, J.; Mucciarelli, A.; Murphy, M. T.; N'Diaye, M.; Neichel, B.; Niedzielski, A. T.; Niemczura, E.; Nortmann, L.; Noterdaeme, P.; Nunes, N. J.; Oggioni, L.; Oliva, E.; Onel, H.; Origlia, L.; Ostlin, G.; Palle, E.; Papaderos, P.; Pariani, G.; Penate Castro, J.; Pepe, F.; Levasseur, L. Perreault; Petit, P.; Pino, L.; Piqueras, J.; Pollo, A.; Poppenhaeger, K.; Quirrenbach, A.; Rauscher, E.; Rebolo, R.; Redaelli, E. M. A.; Reffert, S.; Reid, D. T.; Reiners, A.; Richter, P.; Riva, M.; Rivoire, S.; Rodriguez-Lopez, C.; Roederer, I. U.; Romano, D.; Rousseau, S.; Rowe, J.; Salvadori, S.; Sanna, N.; Santos, N. C.; Diaz, P. Santos; Sanz-Forcada, J.; Sarajlic, M.; Sauvage, J. -F.; Schaefer, S.; Schiavon, R. P.; Schmidt, T. M.; Selmi, C.; Sivanandam, S.; Sordet, M.; Sordo, R.; Sortino, F.; Sosnowska, D.; Sousa, S. G.; Stempels, E.; Strassmeier, K. G.; Suarez Mascareno, A.; Sulich, A.; Sun, X.; Tanvir, N. R.; Tenegi-Sangines, F.; Thibault, S.; Thompson, S. J.; Tozzi, A.; Turbet, M.; Vallee, P.; Varas, R.; Venn, K. A.; Veran, J. -P.; Verma, A.; Viel, M.; Wade, G.; Waring, C.; Weber, M.; Weder, J.; Wehbe, B.; Weingrill, J.; Woche, M.; Xompero, M.; Zackrisson, E.; Zanutta, A.; Zapatero Osorio, M. R.; Zechmeister, M.; Zimara, J., The first generation of ELT instruments includes an optical-infrared high resolution spectrograph, indicated as ELT-HIRES and recently christened ANDES (ArmazoNes high Dispersion Echelle Spectrograph). ANDES consists of three fibre-fed spectrographs (UBV, RIZ, YJH) providing a spectral resolution of similar to 100,000 with a minimum simultaneous wavelength coverage of 0.4-1.8 mu m with the goal of extending it to 0.35-2.4 mu m with the addition of a K band spectrograph. It operates both in seeing- and diffraction-limited conditions and the fibre-feeding allows several, interchangeable observing modes including a single conjugated adaptive optics module and a small diffraction-limited integral field unit in the NIR. Its modularity will ensure that ANDES can be placed entirely on the ELT Nasmyth platform, if enough mass and volume is available, or partly in the Coude room. ANDES has a wide range of groundbreaking science cases spanning nearly all areas of research in astrophysics and even fundamental physics. Among the top science cases there are the detection of biosignatures from exoplanet atmospheres, finding the fingerprints of the first generation of stars, tests on the stability of Nature's fundamental couplings, and the direct detection of the cosmic acceleration. The ANDES project is carried forward by a large international consortium, composed of 35 Institutes from 13 countries, forming a team of more than 200 scientists and engineers which represent the majority of the scientific and technical expertise in the field among ESO member states., The Italian effort for ANDES is supported by the Italian National Institute for Astrophysics (INAF). The Portuguese participation is supported by FCT -Fundacao para a Ciencia e a Tecnologia through national funds and by FEDER through COMPETE2020 -Programa Operacional Competitividade e Internacionalizacao by these grants: UID/FIS/04434/2019, UIDB/04434/2020 & UIDP/04434/2020; POCI-01-0145-FEDER-032113 & PTDC/FIS-AST/32113/2017. Swedish participation in the ANDES project is made possible through the national Swedish ELT Instrumentation Consortium (SELTIC), suppored by the Swedish Research Council (VR). CJM acknowledges FCT and POCH/FSE (EC) support through Investigador FCT Contract 2021.01214.CEECIND/CP1658/CT0001. JLB acknowledges funding from the European Research Council (ERC) under the European Union's Horizon 2020 research and innovation program under grant agreement No 805445. MTM acknowledges the support of the Australian Research Council through Future Fellowship grant FT180100194 SS acknowledges funding from the European Research Council (ERC) under the European Union's Horizon 2020 research and innovation program under grant agreement No 804240. TMS acknowledgment the support from the SNF synergia grant CRSII5-193689 (BLUVES), With funding from the Spanish government through the Severo Ochoa Centre of Excellence accreditation SEV-2017-0709

International audience; The adaptive optics systems of future Extremely Large Telescopes (ELTs) will be assisted with laser guide stars (LGS) which will be created in the sodium layer at a height of ≈90 km above the telescopes. In a Shack–Hartmann wavefront sensor, the long elongation of LGS spots on the sub-pupils far apart from the laser beam axis constraints the design of the wavefront sensor (WFS) which must be able to fully sample the elongated spots without undersampling the non-elongated spots. To fulfill these requirements, a newly released large complementary metal oxide semiconductor sensor with 1100 × 1600 pixels and 9 μm pixel pitch could be employed. Here, we report on the characterization of such a sensor in terms of noise and linearity, and we evaluate its performance for wavefront sensing based on the spot centroid variations. We then illustrate how this new detector can be integrated into a full LGS WFS for both the European Southern Observatory’s ELT and the Thirty Meter Telescope.; Les systèmes d'optique adaptative des futurs Extremely Large Telescopes (ELT) seront assistés par des étoiles guides laser (LGS) qui seront créées dans la couche de sodium à une hauteur de ≈90 km au-dessus des télescopes. Dans un capteur de front d'onde de Shack-Hartmann, la longue élongation des taches LGS sur les sous-pupilles éloignées de l'axe du faisceau laser contraint la conception du capteur de front d'onde (WFS) qui doit être capable d'échantillonner entièrement les taches allongées sans sous-échantillonner les taches non allongées. Pour répondre à ces exigences, un grand capteur à semi-conducteurs d'oxyde de métal complémentaire récemment commercialisé avec 1100 × 1600 pixels et un pas de pixel de 9 μm pourrait être employé. Nous présentons ici la caractérisation d'un tel capteur en termes de bruit et de linéarité, et nous évaluons ses performances pour la détection du front d'onde en fonction des variations du centroïde du spot. Nous illustrons ensuite comment ce nouveau détecteur peut être intégré dans un WFS LGS complet pour l'ELT de l'Observatoire européen austral et le télescope de trente mètres.

Context. In recent decades, direct imaging has confirmed the existence of substellar companions (exoplanets or brown dwarfs) on wide orbits (>10 au) around their host stars. In striving to understand their formation and evolution mechanisms, in 2015 we initiated the SPHERE infrared survey for exoplanets (SHINE), a systematic direct imaging survey of young, nearby stars that is targeted at exploring their demographics. Aims. We aim to detect and characterize the population of giant planets and brown dwarfs beyond the snow line around young, nearby stars. Combined with the survey completeness, our observations offer the opportunity to constrain the statistical properties (occurrence, mass and orbital distributions, dependency on the stellar mass) of these young giant planets. Methods. In this study, we present the observing and data analysis strategy, the ranking process of the detected candidates, and the survey performances for a subsample of 150 stars that are representative of the full SHINE sample. Observations were conducted in a homogeneous way between February 2015 and February 2017 with the dedicated ground-based VLT/SPHERE instrument equipped with the IFS integral field spectrograph and the IRDIS dual-band imager, covering a spectral range between 0.9 and 2.3 μm. We used coronographic, angular, and spectral differential imaging techniques to achieve the best detection performances for this study, down to the planetary mass regime. Results. We processed, in a uniform manner, more than 300 SHINE observations and datasets to assess the survey typical sensitivity as a function of the host star and of the observing conditions. The median detection performance reached 5σ-contrasts of 13 mag at 200 mas and 14.2 mag at 800 mas with the IFS (YJ and YJH bands), and of 11.8 mag at 200 mas, 13.1 mag at 800 mas, and 15.8 mag at 3 as with IRDIS in H band, delivering one of the deepest sensitivity surveys thus far for young, nearby stars. A total of sixteen substellar companions were imaged in this first part of SHINE: seven brown dwarf companions and ten planetary-mass companions.These include two new discoveries, HIP 65426 b and HIP 64892 B, but not the planets around PDS70 that had not been originally selected for the SHINE core sample. A total of 1483 candidates were detected, mainly in the large field of view that characterizes IRDIS. The color-magnitude diagrams, low-resolution spectrum (when available with IFS), and follow-up observations enabled us to identify the nature (background contaminant or comoving companion) of about 86% of our subsample. The remaining cases are often connected to crowded-field follow-up observations that were missing. Finally, even though SHINE was not initially designed for disk searches, we imaged twelve circumstellar disks, including three new detections around the HIP 73145, HIP 86598, and HD 106906 systems. Conclusions. Nowadays, direct imaging provides a unique opportunity to probe the outer part of exoplanetary systems beyond 10 au to explore planetary architectures, as highlighted by the discoveries of: one new exoplanet, one new brown dwarf companion, and three new debris disks during this early phase of SHINE. It also offers the opportunity to explore and revisit the physical and orbital properties of these young, giant planets and brown dwarf companions (relative position, photometry, and low-resolution spectrum in near-infrared, predicted masses, and contrast in order to search for additional companions). Finally, these results highlight the importance of finalizing the SHINE systematic observation of about 500 young, nearby stars for a full exploration of their outer part to explore the demographics of young giant planets beyond 10 au and to identify the most interesting systems for the next generation of high-contrast imagers on very large and extremely large telescopes. © M. Langlois et al. 2021. SPHERE is an instrument designed and built by a consortium consisting of IPAG (Grenoble, France), MPIA (Heidelberg, Germany), LAM (Marseille, France), LESIA (Paris, France), Laboratoire Lagrange (Nice, France), INAF – Osservatorio di Padova (Italy), Observatoire de Genève (Switzerland), ETH Zürich (Switzerland), NOVA (Netherlands), ONERA (France) and ASTRON (Netherlands) in collaboration with ESO. SPHERE was funded by ESO, with additional contributions from CNRS (France), MPIA (Germany), INAF (Italy), FINES (Switzerland) and NOVA (Netherlands). SPHERE also received funding from the European CommissionSixth and Seventh Framework Programmes as part of the Optical Infrared Coordination Network for Astronomy (OPTICON) under grant number RII3-Ct-2004-001566 for FP6 (2004-2008), grant number 226604 for FP7 (2009-2012) and grant number 312430 for FP7 (2013-2016). This paper is based on observations collected at the European Southern Observatory under ESO programmes 198.C-0209, 097.C-0865, 095.C-0298, 095.C-0309,096.C-0241. This work has made use of the SPHERE Data Centre, jointly operated by OSUG/IPAG (Grenoble), PYTHEAS/LAM/CeSAM (Marseille), OCA/Lagrange (Nice), Observatoire de Paris/LESIA (Paris), and Observatoire de Lyon (OSUL/CRAL). This work is supported by the French National Research Agency in the framework of the Investissements d’Avenir program (ANR-15-IDEX-02), through the funding of the “Origin of Life” project of the Univ. Grenoble-Alpes. This work is jointly supported by the French National Programms (PNP and PNPS) and by the Action Spécifique Haute Résolution Angulaire (ASHRA) of CNRS/INSU co-funded by CNES. We also thank the anonymous referee for her/his careful reading of the manuscript as well as her/his insightful comments and suggestions. AV acknowledges funding from the European Research Council (ERC) under the European Union’s Horizon 2020 research and innovation programme (grant agreement No. 757561). A.-M.L. acknowledges funding from French National Research Agency (GIPSE project). C.P. acknowledges financial support from Fondecyt (grant 3190691) and financial support from the ICM (Iniciativa Científica Milenio) via the Núcleo Milenio de Formación Planetaria grant, from the Universidad de Valparaíso. T.H. acknowledges support from the European Research Council under the Horizon 2020 Framework Program via the ERC Advanced Grant Origins 832428.

International audience; The pyramid wavefront sensor (PWFS), due to its extremely high sensitivity in comparison to the Shack-Hartmann WFS, is the design choice of most single-conjugate adaptive optics (AO) instruments currently being developed for extremely large telescopes (ELTs). This sensitivity benefit is served, however, with several technical drawbacks to overcome, one of which is the intrinsic non-linearity of the sensor. Even in modulated operation, the gradient measurement saturation non-linearity is strongly exacerbated by in-loop phase residuals for typical on-sky regimes, with high spatial frequencies inducing a dramatic sensitivity reduction for the controlled modes. This phenomenon has been dubbed "optical gain", and it was demonstrated that a modal gain compensation on an appropriate control basis provides an adequate mitigation of the sensitivity reduction, and improves the end-to-end performance on ELT SCAO systems across all relevant guide star magnitudes and seeing conditions. Several techniques have been proposed to achieve this nominal performance recovery, however most require offline computation of interaction matrices; or some alterations to the usual AO loop operation. In this paper, we present the CLOSE (Correlation-Locked Optimization StratEgy) algorithm, which achieves determination of the modal gains, in a real-time fashion, through the sole use of the modal decomposition of the WFS measurements. Real-time estimators are implemented to implicitly measure resonance levels of the integrator transfer function, which is used as a proxy to control the modal gains through a second-layer servo loop. Using this method, we achieve compensation of the optical gain in the command law, and a fully automatic optimization of the modal integrator depending on the signal-to-noise level. Simulated end-to-end results are presented, for stationary or quickly varying seeing conditions, all at the scale of the MICADO SCAO design on the ELT. We also discuss the applicability of the CLOSE scheme on other known AO problems.

International audience; The determination of the optical point spread function (PSF) or a model thereof is one key step in the estimation of key astronomical quantities for most science cases. Yet it has proven quite challenging due to crowding or the total absence of point-sources in the field or variability (time, angle and wavelength). For Adaptive-optics (AO) assisted observations, alternative techniques exist such as PSF reconstruction (PSF-R) which relies on the AO control loop data. Our goal is to provide a standardized nomenclature and categorization of the techniques that use focal-plane data (numerical extraction, parametric model-fitting), recovery from telemetry (reconstruction, analytic or Monte Carlo modeling) or both jointly combined (hybrid, deconvolution) in an attempt to gain insight into the advantages and shortcomings of such techniques. Applicability to AO systems on Giant Segmented Mirror Telescopes (GSMT) is our main motivation.

The TMT first light Adaptive Optics (AO) facility consists of the Narrow Field Infra-Red AO System (NFIRAOS) and the associated Laser Guide Star Facility (LGSF). NFIRAOS is a 60 x 60 laser guide star (LGS) multi-conjugate AO (MCAO) system, which provides uniform, diffraction-limited performance in the J, H, and K bands over 17-30 arc sec diameter fields with 50 per cent sky coverage at the galactic pole, as required to support the TMT science cases. NFIRAOS includes two deformable mirrors, six laser guide star wavefront sensors, and several low-order, infrared, natural guide star wavefront sensors within each client instrument. The first light LGSF system includes six sodium lasers required to generate the NFIRAOS laser guide stars. In this paper, we will provide an update on the progress in designing, modeling and validating the TMT first light AO systems and their components over the last two years. This will include the final design activities for NFIRAOS, preliminary design activities for the LGSF, final design and prototyping activities for the deformable mirrors, final design and fabrication for the visible detectors, preliminary design activities for the NFIRAOS visible cameras, preliminary design activities for the NFIRAOS Real Time Controller (RTC) and development and tests of prototype candidate lasers. Comprehensive and detailed AO modeling is also continuing to support the design and development of the first light AO facility.

International audience; Assembly, Integration, Test and Validation (AIT/V) phases for AO instruments, in laboratory as in the telescope, represent numerous technical challenges. The Laboratoire d’Astrophysique de Marseille (LAM) is in charge of the AIT/V preparation and planning for the MOSAIC (ELT-MOS) instrument, from identification of needs, challenges, risks, to defining the optimal AIT strategy for this highly modular and serialized instrument. In this paper, we present the status of this study and describe several AIT/V scenarios as well as a planning for AIT phases in Europe and in Chile. We also show our capabilities, experience and expertise to lead the instrument MOSAIC AIT/V activities.

The preparations for the design and construction of the Extremely Large Telescope (ELT) are in full swing. One of the most critical components of this enormous telescope is its segmented primary mirror (M1), for which Netherlands Organisation for Applied Scientific Research (TNO), in collaboration with VDL, has designed the mechanical segment support (M1SS) in the period 2015-2016.1 This new M1SS design is based on the previous M1SS prototypes developed in 2009-2010,2 but includes several enhancements to further improve its performance. Specific design drivers were, among others, the serviceability of the M1SS, the introduced surface form error at the segment, and the increased target values for the structural eigenfrequencies. The latter defines the dynamic performance of the structure (including the ∼178 kg segment), which needed to be validated experimentally. From the latest M1SS design one engineering model (EM) and six qualification models (QMs) have been manufactured recently, which have tested intensively to verify their performance. This work will present the test procedure employed to validate the dynamic behavior, describe these dynamic tests and present their results in detail. During these tests a QM, including a dummy segment, has been placed on a heavy rigid structure and three accelerometers have been mounted across the assembly. The structure has then been excited on several strategic locations using a roving hammer technique,3 resulting in a large collection of frequency responses. From these, the eigenfrequencies and accompanying mode shapes have been estimated, resulting in accurate determination of the clocking, lateral, piston and tip/tilt modes of the structure. This allows for correct assessment of the dynamic performance and comparison to the design objectives and finite element model (FEM) predictions. This procedure has been applied to two different QMs, but since each M1SS consists of a fixed frame (FF) and a removable segment assembly (SA), four different configurations have been tested. The results demonstrate compliance with the challenging design objectives for all QMs, and they show only small variations among the configurations, demonstrating that the dynamic performance of the M1SS design is very reproducible.

We present the results from the phase A study of ELT-HIRES, an optical-infrared High Resolution Spectrograph for ELT, which has just been completed by a consortium of 30 institutes from 12 countries forming a team of about 200 scientists and engineers. The top science cases of ELT-HIRES will be the detection of life signatures from exoplanet atmospheres, tests on the stability of Nature's fundamental couplings, the direct detection of the cosmic acceleration. However, the science requirements of these science cases enable many other groundbreaking science cases. The baseline design, which allows to fulfil the top science cases, consists in a modular fiber- fed cross-dispersed echelle spectrograph with two ultra-stable spectral arms providing a simultaneous spectral range of 0.4-1.8 ¿m at a spectral resolution of 100,000. The fiber-feeding allows ELT-HIRES to have several, interchangeable observing modes including a SCAO module and a small diffraction-limited IFU.© 2018 SPIE., The Italian contribution to this project is supported by a specific grant provided by INAF, the Italian National Institute for Astrophysics. The Portuguese team was supported by Fundacao para a Ciencia e a Tecnologia (FCT, Portugal) through the research grant through national funds and by FEDER through COMPETE2020 by grants UID/FIS/04434/2013 & POCI-01-0145-FEDER-007672 and PTDC/FIS-AST/1526/2014 & POCI-01-0145-FEDER-016886. N.C.S. also acknowledges support from FCT through Investigador FCT contract IF/00169/2012/CP0150/CT0002. CAP, MA, AF, JIGH, JLR, RR, and FT acknowledge the Spanish ministry project MINECO AYA2014-56359-P. JIGH also acknowledges financial support from the Spanish Ministry of Economy and Competitiveness (MINECO) under the 2013 Ramon y Cajal program MINECO RYC-2013-14875.

The Exo-Life Finder (ELF) will be an optical system with the resolving power of a ≥20m telescope optimized for characterizing exoplanets and detecting exolife. It will allow for direct detection of Earth-size planets in commonlyconsidered water-based habitable zones (WHZ) of nearby stars and for generic exolife studies. Here we discuss capabilities of the ELF to detect biosignatures and technosignatures in exoplanetary atmospheres and on their surfaces in the visual and near infrared. We evaluate sensitivity limits for mid- and low-resolution spectral, photometric and polarimetric measurements, analyzed using atmosphere models and light-curve inversions. In particular, we model and estimate integration times required to detect O2, O3, CO2, CH4, H2O and other biosignature gases and habitability markers. Disequilibrium biosignature pairs such as O2+CH4 or CO2+CH4–CO are also explored. Photosynthetic and nonphotosynthetic pigments are other important biosignatures that ELF will search for in atmospheres and on resolved surfaces of exoplanets, in the form of bioaerosols and colonies of organisms. Finally, possible artificial structures on exoplanet surfaces and in near-exoplanet space can be detected. Practical instrument requirements are formulated for detecting these spectral and structural biosignatures and technosignatures. It is imperative that such a study is applied first to characterize the nearest exoplanet Proxima b, then to search for exo-Earths in the Alpha Cen A and B system and other near-Sun stars, and finally to explore larger exoplanets around more distant stars.

The preparations for the design and construction of the Extremely Large Telescope (ELT) are in full swing. One of the most critical components of this enormous telescope is its segmented primary mirror (M1), for which Netherlands Organisation for Applied Scientific Research (TNO), in collaboration with VDL, has designed the mechanical segment support (M1SS) in the period 2015-2016.1 This new M1SS design is based on the previous M1SS prototypes developed in 2009-2010,2 but includes several enhancements to further improve its performance. Specific design drivers were, among others, the serviceability of the M1SS, the introduced surface form error at the segment, and the increased target values for the structural eigenfrequencies. The latter defines the dynamic performance of the structure (including the ∼178 kg segment), which needed to be validated experimentally. From the latest M1SS design one engineering model (EM) and six qualification models (QMs) have been manufactured recently, which have tested intensively to verify their performance. This work will present the test procedure employed to validate the dynamic behavior, describe these dynamic tests and present their results in detail. During these tests a QM, including a dummy segment, has been placed on a heavy rigid structure and three accelerometers have been mounted across the assembly. The structure has then been excited on several strategic locations using a roving hammer technique,3 resulting in a large collection of frequency responses. From these, the eigenfrequencies and accompanying mode shapes have been estimated, resulting in accurate determination of the clocking, lateral, piston and tip/tilt modes of the structure. This allows for correct assessment of the dynamic performance and comparison to the design objectives and finite element model (FEM) predictions. This procedure has been applied to two different QMs, but since each M1SS consists of a fixed frame (FF) and a removable segment assembly (SA), four different configurations have been tested. The results demonstrate compliance with the challenging design objectives for all QMs, and they show only small variations among the configurations, demonstrating that the dynamic performance of the M1SS design is very reproducible.

Europe is currently preparing the largest telescope of the world: the E-ELT (European Extremely Large Telescope). Planned by 2026, this huge telescope (diameter: 39 m) will allow to answer fundamental questions of contemporary astrophysics by imaging exoplanets or studying large scales of universe. However, images of astrophysical objects done by ground based telescopes suffer from the distortion caused by the atmospheric turbulence which reduces the capacity of instruments to distinguish objects too close to each other.The Adaptive Optics (AO) is a technique which allows to restore this loss of angular resolution by correcting the effects of atmospheric turbulence. In operation on several astronomical observatories for almost 20 years, it is now applied to other domains where imaging suffers from inhomogeneous media as cellular microscopy, ophthalmology, functional imaging, etc. This technology is based on a deformable mirror which corrects in real time the incoming wave front by using information coming from a sensor which measures the turbulent phase called "WaveFront Sensor" (WFS).Until very recently, the great majority of AO systems had used the Shack-Hartmann WFS. New concepts based on Fourier filtering have however just been put in operation in several professional observatories and their results seem to outperform the Shack-Hartmann. We mention in particular the Pyramid WFS which provides images with an astonishing quality at the Large Binocular Telescope or the Zernike WFS which allows to considerably improve the performance of the exoplanets imager at the Very Large Telescope.In spite of these instrumental achievements, these Fourier based WFSs are still lacking of maturity. Since they would potentially be chosen for the AO systems of the future Extremely Large Telescopes, this thesis aims to consolidate their theoretical understanding and to optimize these Fourier based WFSs.We firstly developed a mathematical framework where the optical theories of diffraction are applied to the Fourier based wave front sensing. Resulting in general equations, it allows to describe all the WFSs based on this concept (as Pyramid and Zernike WFSs). They are, for the first time, unified under the same formalism. Secondly we developed a common performance criteria following the usual requirements of astronomical adaptive optics in order to rigorously compare these sensors.Another consequence of this theoretical framework's development is then introduced to test new WFSs which derive from the pre-existent designs. It allows us to introduce the notion of "WFSs class" which consists in a generalization of the existing sensors with original parameters which become flexible: from two Zernike and Pyramid WFSs we get an infinity of sensors in the Zernike's and Pyramid's WFSs classes.We then explored these two classes using both numerical simulations and analytical approach. The objective was to identify the influence of class' parameters on performance criteria in order to optimize optical designs with regard to the instrumental requirements. New configurations of the Pyramid class, that we called "Flattened pyramids", show promising behaviors and are studied in details.The thesis ends with the presentation of an optical bench able to generate almost all of the Fourier based WFSs which would allow to validate experimentally the predicted theoretical results., L'Europe prépare actuellement le plus grand télescope du monde : l'E-ELT (European Extremely Large Telescope). Prévu vers 2026, ce télescope géant (diamètre: 39 m) permettra de répondre à des questions fondamentales de l'astrophysique contemporaine, depuis l'imagerie d'exoplanètes jusqu'à l'étude des grandes échelles de l'univers. Cependant, l'imagerie d'objets astrophysiques depuis des télescopes au sol est fortement perturbée par l'effet des mouvements de masses d'air dans l'atmosphère réduisant ainsi la capacité des instruments au sol à distinguer deux objets proches.L'Optique Adaptative (OA) permet de restaurer cette résolution angulaire en corrigeant les effets de la turbulence atmosphérique. Cette technique, en plein essor en astronomie, s'exporte d'ailleurs actuellement aux nombreux autres domaines où l'imagerie pâtit d'un milieu inhomogène spatialement et temporellement comme la microscopie cellulaire, l'ophtalmologie, l'imagerie fonctionnelle, etc. Cette technologie s'appuie sur un (ou plusieurs) miroir(s) déformable(s) qui corrige(nt) en temps réel le front d'onde incident en utilisant les données provenant d'un (ou plusieurs) instrument(s) de mesure de la phase turbulente appelé "Analyseur de Surface d'Onde" (ASO). Jusqu'à très récemment, la grande majorité des systèmes d'OA utilisaient des ASO de type Shack-Hartmann. Des concepts concurrents basés sur le filtrage optique de Fourier viennent cependant d'être mis en fonctionnement dans plusieurs observatoires professionnels et leurs résultats semblent surpasser les performances du Shack-Hartmann. On mentionne notamment le senseur Pyramide qui a fourni des images d'une qualité sans précédent depuis le sol au Large Binocular Telescope ou l'analyseur Zernike qui a permis d'améliorer considérablement les performances de l'imageur d'exoplanètes du Very Large Telescope. En dépit de ces prouesses instrumentales, ces senseurs manquent encore de maturité et le retour sur expérience des systèmes opérationnels reste très faible. En vue de leur potentielle utilisation sur les Extremely Large Telescopes, cette thèse vise à consolider leur compréhension théorique ainsi qu'à optimiser ces ASO basés sur le filtrage de Fourier. Est développé dans un premier temps un cadre mathématique où les théories de diffraction optiques sont appliquées à l'analyse de front d'onde par filtrage de Fourier. Les équations très générales qui en émergent permettent de décrire tous les ASO basés sur ce principe (tels les ASO Pyramide et Zernike) qui se trouvent ainsi pour la première fois rassemblés sous un unique formalisme. Dans un second temps sont développés des critères de performance communs inspirés des besoins de l'optique adaptative astronomique en vue d'une comparaison rigoureuse de ces senseurs.Une conséquence logique de l'effort théorique précédent est ensuite présentée : puisqu'un cadre de comparaison existe pourquoi ne pas en profiter pour tester de nouveaux ASO qui seraient par exemple générés à partir des designs préexistants ? De ce questionnement apparaît ainsi naturellement la notion de "classe d'analyseurs de front d'onde" qui consiste en une généralisation des senseurs existants pour lesquels des grandeurs à l'origine fixées deviennent des degrés de liberté : des deux ASO Zernike et Pyramide, se dégage une infinité de dispositifs en les classes d'ASO de Zernike et de la Pyramide.Celles-ci sont ensuite explorées analytiquement et via des simulations numériques. L'objectif est d'identifier quel paramètre de classe joue sur quel critère de performance afin d'envisager une optimisation des designs optiques au regard des attentes instrumentales. Des configurations inédites de la classe Pyramide, ASO que l'on appelle "Pyramides aplaties", s'avèrent notamment très prometteuses et font l'objet d'une étude plus poussée.L'exposé se conclut par la présentation d'un banc optique capable de simuler la quasi-totalité des ASO à filtrage de Fourier ce qui permettrait de valider expérimentalement les résultats théoriques prédits.

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

MAORY is one of the four instruments for the E-ELT approved for construction. It is an adaptive optics module offering two compensation modes: multi-conjugate and single-conjugate adaptive optics. The project has recently entered its phase B. A system-level overview of the current status of the project is given in this paper.

We present the main results of the performance test campaign of the Mid-Infrared European Extremely Large Telescope Imager and Spectrograph (METIS) Cold Chopper Demonstrator (MCCD). This tip/tilt mirror, which operates at a temperature of 77 K, is one of the critical components in the METIS for the European Extremely Large Telescope. The performance requirements of the MCCD relate to the field of fast and very accurate reference tracking. We discuss the applicability of different high-performance motion control strategies and describe the control synthesis of a repetitive and of a novel hybrid controller. We identified the presence of nonlinearities in the plant, which limits the performance of the hybrid controller. The repetitive controller shows very promising results and can handle the nonlinearities in the system. This experimental phase concludes the MCCD program, which was initiated to verify the feasibility of a high-performance cryogenic tip/tilt mirror at an early stage in the METIS development. Because of the very promising test results, no significant changes to the hardware will be implemented. We believe that minor adjustments will suffice to meet all requirements of the final hardware after integration with the METIS instrument.

We present the main results of the performance test campaign of the Mid-Infrared European Extremely Large Telescope Imager and Spectrograph (METIS) Cold Chopper Demonstrator (MCCD). This tip/tilt mirror, which operates at a temperature of 77 K, is one of the critical components in the METIS for the European Extremely Large Telescope. The performance requirements of the MCCD relate to the field of fast and very accurate reference tracking. We discuss the applicability of different high-performance motion control strategies and describe the control synthesis of a repetitive and of a novel hybrid controller. We identified the presence of nonlinearities in the plant, which limits the performance of the hybrid controller. The repetitive controller shows very promising results and can handle the nonlinearities in the system. This experimental phase concludes the MCCD program, which was initiated to verify the feasibility of a high-performance cryogenic tip/tilt mirror at an early stage in the METIS development. Because of the very promising test results, no significant changes to the hardware will be implemented. We believe that minor adjustments will suffice to meet all requirements of the final hardware after integration with the METIS instrument.

We present an overview of the design of IRIS, an infrared (0.84 - 2.4 micron) integral field spectrograph and imaging camera for the Thirty Meter Telescope (TMT). With extremely low wavefront error (, Ground-Based and Airborne Instrumentation for Astronomy V, June 22-26, 2014, Series: Proceedings of SPIE; no. 9147

We describe measurements of both the vibration forces imparted by various types of observatory equipment, and the transmission of these forces through the soil, foundations and telescope pier. These are key uncertainties both in understanding how to mitigate vibration at existing observatories and for developing a vibration budget in the design of future observatories such as the Thirty Meter Telescope. Typical vibration surveys have measured only the resulting motion (acceleration); however, this depends on both the source and the system being excited (for example, isolating equipment results in less force being transmitted, but greater motion of the equipment itself). Instead, here we (a) apply a known force input to the pier from a shaker and measure the response at different locations, and (b) use isolator properties combined with measured acceleration to infer the forces applied by various equipment directly. The soil foundation and pier transmission can then be combined with a finite element model based vibration transmission analysis to estimate the optical consequences. Estimates of plausible source levels supports the development of a vibration budget for TMT that allocates allowable forces to the sources of vibration; this is described in a companion paper., Ground-Based and Airborne Telescopes V, June 22-27, 2014, Series: Proceedings of SPIE; no. 9145

The Thirty Meter Telescope (TMT) with its first-light multi-conjugate adaptive optics system, NFIRAOS, and high-resolution imager, IRIS, is expected to take differential astrometric measurements with an accuracy on the order of tens of micro arcsec. This requires the control, correction, characterization and calibration of a large number of error sources and uncertainties, many of which have magnitudes much in excess of this level of accuracy. In addition to designing the observatory such that very high precision and accuracy astrometric observations are enabled, satisfying the TMT requirements can only be achieved by a careful calibration, observation and data reduction strategy. In this paper, we present descriptions of the individual errors sources, how and when they apply to different astrometry science cases and the mitigation methods required for each of them, as well as example results for individual error terms and the overall error budgets for a variety of different science cases., Adaptive Optics Systems IV, June 22-27, 2014, Series: Proceedings of SPIE; no. 9148

We present recent experimental results obtained with CILAS deformable mirrors (DMs) or demonstration prototypes in solar and night-time astronomy (with ground-based telescopes) as well as observation of the Earth (with space telescopes). These important results have been reached thanks to CILAS technology range composed of monomorph and piezostack deformable mirrors, drivers and optical coatings. For instance, the monomorph technology, due to a simple architecture can offer a very good reliability for space applications. It can be used for closed or open loop correction of the primary mirror deformation (thermal and polishing aberrations, absence of gravity). It can also allow a real-time correction of wavefront aberrations introduced by the atmosphere up to relatively high spatial and temporal frequencies for ground-based telescopes. The piezostack technology is useful for very high order correction at high frequency and under relatively low operational temperature (down to -30°C), which is required for future Extremely Large Telescopes (ELTs). This wide range of applications is exposed through recent examples of DMs performances in operation and results obtained with breadboards, allowing promising DMs for future needs., Adaptive Optics Systems IV, June 22-27, 2014, Series: Proceedings of SPIE; no. 9148

The TMT first light Adaptive Optics (AO) facility consists of the Narrow Field Infra-Red AO System (NFIRAOS) and the associated Laser Guide Star Facility (LGSF). NFIRAOS is a 60 × 60 laser guide star (LGS) multi-conjugate AO (MCAO) system, which provides uniform, diffraction-limited performance in the J, H, and K bands over 17-30 arc sec diameter fields with 50 per cent sky coverage at the galactic pole, as required to support the TMT science cases. NFIRAOS includes two deformable mirrors, six laser guide star wavefront sensors, and three low-order, infrared, natural guide star wavefront sensors within each client instrument. The first light LGSF system includes six sodium lasers required to generate the NFIRAOS laser guide stars. In this paper, we will provide an update on the progress in designing, modeling and validating the TMT first light AO systems and their components over the last two years. This will include pre-final design and prototyping activities for NFIRAOS, preliminary design and prototyping activities for the LGSF, design and prototyping for the deformable mirrors, fabrication and tests for the visible detectors, benchmarking and comparison of different algorithms and processing architecture for the Real Time Controller (RTC) and development and tests of prototype candidate lasers. Comprehensive and detailed AO modeling is continuing to support the design and development of the first light AO facility. Main modeling topics studied during the last two years include further studies in the area of wavefront error budget, sky coverage, high precision astrometry for the galactic center and other observations, high contrast imaging with NFIRAOS and its first light instruments, Point Spread Function (PSF) reconstruction for LGS MCAO, LGS photon return and sophisticated low order mode temporal filtering., Adaptive Optics Systems IV, June 22-27, 2014, Series: Proceedings of SPIE; no. 9148

Direct imaging and low-resolution spectroscopy of extrasolar planets are exciting but challenging scientific applications of coronagraphy. While the angular separation is well within the reach of actual telescope in the near IR or visible, the planet-star contrast (from 10-6 to 10-10) requires wavefront quality and stability hard to reach even with a well-polished space telescope. Several solutions have been proposed to tackle the speckle noise introduced by the residual optical defects. While some concepts rely only on active wavefront correction using deformable mirror, other techniques are based on post-processing and subtract a reference image recorded sometimes simultaneously with the science image. One interesting solution is to choose a concept that allows both active correction and post-processing of high contrast coronagraphic images. This is the case of the Self Coherent Camera (SCC), which has been proposed for the project of space coronagraph SPICES and for the ground-based planet finder EPICS studied for the European Extremely Large Telescope. After recalling the SCC principle, we present both monochromatic and modest bandwidth (2%) experimental results of Dark Hole in the focal plane using a SCC. Example of a post-processing result with SCC is also given to emphasize the interest of combining it with active correction. © 2012 SPIE., Ground-Based and Airborne Instrumentation for Astronomy IV, July 1-6, 2012, Amsterdam, The Netherlands, Series: Proceedings of SPIE; no. 8446

An overview of the current status of the Thirty Meter Telescope (TMT) instrumentation program is presented. Science cases and operational concepts as well as their links to the instruments are continually revisited and updated through a series of workshops and conferences. Work on the three first-light instruments (WFOS IRIS, and IRMS) has made significant progress, and many groups in TMT partner communities are developing future instrument concepts. Other instrument-related subsystems are also receiving considerable attention given their importance to the scientific end-toend performance of the Observatory. As an example, we describe aspects of the facility instrument cooling system that are crucially important to successful diffraction-limited observations on an extremely large telescope. © 2012 SPIE., Ground-Based and Airborne Instrumentation for Astronomy IV, July 1-6, 2012, Amsterdam, The Netherlands, Series: Proceedings of SPIE; no. 8446

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

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

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

The University of Victoria Adaptive Optics Laboratory, the Herzberg Institute of Astrophysics and Subaru Observatory are building a Multi-Object Adaptive Optics (MOAO) technology and science demonstrator called Raven. Raven will be mounted on the Subaru NIR Nasmyth platform and will feed the IRCS imager and spectrograph. The baseline design calls for three natural guide star (NGS) wavefront sensors (WFS), one on-axis laser guide star (LGS) WFS and two science pickoff arms that will patrol a 3.5 arcminute diameter field of regard (FOR). Sky coverage is an important consideration for a science demonstrator. End-to-end simulations of Raven show that a 10x10 subaperture adaptive optics (AO) system can meet the science requirements, i.e. 30 per cent of the energy ensquared (EE) within a 140mas slit using three R less than 14 NGSs, and almost 40 per cent EE with the addition of the central LGS. We present here an overview of the Raven project.

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

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

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

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