This PDF file contains the front matter associated with SPIE Proceedings Volume 10703, including the Title Page, Copyright information, Table of Contents, Author and Conference Committee lists.

The Adaptive Optics Facility (AOF) is an ESO project, which transformed Yepun, one of the four 8m telescopes in Paranal, into an adaptive telescope. This has been done by replacing the conventional secondary mirror of Yepun by a Deformable Secondary Mirror (DSM) and attaching four Laser Guide Stars (LGS) Units to its centerpiece. Additionally, two Adaptive Optics (AO) modules (GALACSI serving MUSE a 3D spectrograph, and GRAAL, serving Hawk I a wide field infrared imager) have been assembled onto the telescope Nasmyth adapters, each of them incorporating four LGS WaveFront Sensors (WFS) and one tip-tilt sensor used to control the DSM at 1 kHz frame rate. The complete AOF is installed on Yepun for more than one year now, and its commissioning is fully complete. This paper presents the most important and amazing features of the AOF, illustrated by some first science images obtained using MUSE/GALACSI in Ground Layer AO (GLAO) and Laser Tomography AO (LTAO) mode, and HAWK-I/GRAAL in GLAO mode. In the first part of the paper, on-sky performance of GRAAL and GALACSI is presented in terms of gain in image quality and even Strehl Ratio. Efficiency of the on-sky operation of the AOF is described. In the second part, future instruments making use of the AOF capabilities are presented.

ERIS is the new AO instrument for VLT-UT4 led by a Consortium of Max-Planck Institut fuer Extraterrestrische Physik, UK-ATC, ETH-Zurich, NOVA-Leiden, ESO and INAF. The ERIS AO system provides NGS mode to deliver high contrast correction and LGS mode to extend high Strehl performance to large sky coverage. The AO module includes NGS and LGS wavefront sensors and, with VLT-AOF Deformable Secondary Mirror and Laser Facility, will provide AO correction to the high resolution coronagraphic imager NIX (1-5um) and the IFU spectrograph SPIFFIER (1-2.5um). In this paper, we present the final design of the ERIS AO system and the status of the of current MAIV phase.

The CHARA array is an optical/near infrared interferometer consisting of six 1-meter diameter telescopes, the longest baseline of which is 331 meters. With sub-millisecond angular resolution, the CHARA array is able to spatially resolve nearby stellar systems and reveal their detailed structures. To improve the sensitivity and scientific throughput, the CHARA array was funded by NSF-ATI in 2011 for an upgrade of adaptive optics (AO) systems to all six telescopes. This first grant covered Phase I of the adaptive optics system, which includes an on-telescope Wavefront Sensor (WFS) and non-common-path (NCP) error correction. Phase II of the program was funded by the NSF/MRI in 2016, and includes purchasing and installing the deformable mirrors at each telescope to complete the system. In this paper we will discuss both phases of the program, how the challenge of AO differs for interferometry, and the first results of the full system.

As astronomers, we are living an exciting time for what concerns the search for other worlds. Recent discoveries have already deeply impacted our vision of planetary formation and architectures. Future bio-signature discoveries will probably deeply impact our scientific and philosophical understanding of life formation and evolution. In that unique perspective, the role of observation is crucial to extend our understanding of the formation and physics of giant planets shaping planetary systems. With the development of high contrast imaging techniques and instruments over more than two decades, vast efforts have been devoted to detect and characterize lighter, cooler and closer companions to nearby stars, and ultimately image new planetary systems. Complementary to other planet-hunting techniques, this approach has opened a new astrophysical window to study the physical properties and the formation mechanisms of brown dwarfs and planets. I will briefly review the different observing techniques and strategies used, the main samples of targeted stars, the key discoveries and surveys, to finally address the main results obtained so far about the physics and the mechanisms of formation and evolution of young giant planets and planetary system architectures.

Here we report on the status of the The Keck Planet Imager and Characterizer (KPIC), which is an on-going series of upgrades to the W.M. Keck II adaptive optics system and instrument suite focused on exoplanet imaging and spectroscopic characterization. The KPIC infrared pyramid wavefront sensor and fiber injection unit to high-resolution infrared spectrograph NIRSPEC have been assembled, integrated and are under-going tests at the University of Hawaii before installation at the Summit in the Fall of 2018.

We report on initial results from the largest infrared AO direct imaging survey searching for wide orbit (≳ 100 AU) massive exoplanets and brown dwarfs as companions around young nearby stars using Robo-AO at the 2.1-m telescope on Kitt Peak, Arizona. The occurrence rates of these rare substellar companions are critical to furthering our understanding of the origin of planetary-mass companions on wide orbits. The observing efficiency of Robo-AO allows us to conduct a survey an order of magnitude larger than previously possible. We commissioned a low-noise high-speed SAPHIRA near-infrared camera to conduct this survey and report on its sensitivity, performance, and data reduction process.

MagAO-X is an entirely new extreme adaptive optics system for the Magellan Clay 6.5 m telescope, funded by the NSF MRI program starting in Sep 2016. The key science goal of MagAO-X is high-contrast imaging of accreting protoplanets at Hα. With 2040 actuators operating at up to 3630 Hz, MagAO-X will deliver high Strehls (> 70%), high resolution (19 mas), and high contrast (< 1 × 10^-4 ) at Hα (656 nm). We present an overview of the MagAO-X system, review the system design, and discuss the current project status.

The Large Binocular Telescope has two adaptive secondary mirrors (ASMs). Each of these feed four focal stations, three of which are equipped with wavefront sensors (WFS) to provide the signal for adaptive optics (AO) correction. These are (1) FLAO - the on-axis natural guide star system feeding the two LUCI NIR imagers/spectrographs, (2) ARGOS - the ground-layer adaptive optics laser-guide star system, which shares the same port as FLAO, (3) LBTI - the 2-11 micron Fizeau/Nulling interferometer, and (4) Linc-Nirvana - the MCAO system. In this paper, we report on the current status of the AO facilities, FLAO, ARGOS, and the ASMs as well as the (1) detector and performance upgrades to FLAO and LBTI wavefront sensors, i.e. the SOUL project, and (2) improvements to the ASMs’ electronics. We also present improvements to the FLAO operation and checkout procedures.

This paper reports on early commissioning of LINC-NIRVANA (LN), an innovative Multi-Conjugate Adaptive Optics (MCAO) system for the Large Binocular Telescope (LBT). LN uses two, parallel MCAO systems, each of which corrects turbulence at two atmospheric layers, to deliver near diffraction-limited imagery over a two-arcminute field of view. We summarize LN’s approach to MCAO and give an update on commissioning, including the achievement of First Light in April 2018. This is followed by a discussion of challenges that arise from our particular type of MCAO and the solutions implemented. We conclude with a brief look forward to the remainder of commissioning and future upgrades.

The GTC AO system designed and developed during the last years is based on a single deformable mirror with 21 x 21 actuators, conjugated to the telescope pupil, and a Shack-Hartmann wavefront sensor with 20 x 20 subapertures, using an OCAM2 camera. The GTCAO system will provide a corrected beam with a Strehl Ratio (SR) of 0.65 in K-band with bright natural guide stars. This paper reports the updated status of the integration of GTCAO in the IAC laboratory, and the results obtained in the first tests carried out to evaluate the performance of the system, before the complete characterization and the verification of the requirements. The wavefront sensor verification has been completed, and it has been integrated in the optical bench together with the corrector optics including the CILAS deformable mirror. The calibration system, also mounted on the optical bench, includes light sources used to tune, characterise and calibrate the whole system. It also simulates the atmospheric turbulence and the telescope, delivering an aberrated wavefront used to debug the whole control system, and to test the real time control software, the servo loop and different servo control strategies. Finally the Test Camera has been also integrated at the science focus to evaluate the performance.

Exo-Planets search and characterization has been the science case driving the SHARK-NIR design, which is one of the two coronagraphic instruments proposed for the Large Binocular Telescope. In fact, together with SHARK-VIS (working in the visible domain), it will offer the possibility to do binocular observations combining direct imaging, coronagraphic imaging and coronagraphic low resolution spectroscopy in a wide wavelength domain, going from 0.5μm to 1.7μm. Additionally, the contemporary usage of LMIRCam, the coronagraphic LBTI NIR camera, working from K to L band, will extend even more the covered wavelength range. The instrument has been designed with two intermediate pupil planes and three focal planes, in order to give the possibility to implement a certain number of coronagraphic techniques, with the purpose to select a few of them matching as much as possible the requirements of the different science cases in terms of contrast at various distances from the star and in term of required field of view. SHARK-NIR has been approved by the LBT board in June 2017, and the procurement phase started just after. We report here about the project status, which is currently at the beginning of the AIV phase at INAF-Padova, and should last about one year. Even if exo-planets is the main science case, the SOUL upgrade of the LBT AO will increase the instrument performance in the faint end regime, allowing to do galactic (jets and disks) and extra-galactic (AGN and QSO) science on a relatively wide sample of targets, normally not reachable in other similar facilities.

The Wavefront Correction (WFC) system for the Daniel K. Inouye Solar Telescope (DKIST) is in its final stages of laboratory integration. All optical, mechanical, and software components have been unit tested and installed and aligned in our laboratory testbed in Boulder, CO. We will verify all aspects of WFC system performance in the laboratory before disassembling and shipping it to Maui for final integration with the DKIST in early 2019. The DKIST Adaptive Optics (AO) system contains a 1600-actuator deformable mirror, a correlating Shack- Hartmann wavefront sensor, a fast tip-tilt mirror, and an FPGA-based control system. Running at a nominal rate of 1975 Hz, the AO system will deliver diffraction-limited images to five of the DKIST science instruments simultaneously. The DKIST AO system is designed to achieve the diffraction limit (on-axis Strehl > 0.3) at wavelengths up to 500 nm in median daytime seeing (r₀ = 7 cm). In addition to AO for diffraction-limited observing, the DKIST WFC system has a low-order wavefront sensor for sensing quasi-static wavefront errors, a context viewer for telescope pointing and image quality assessment, and an active optics engine. The active optics engine uses inputs from the low-order wavefront sensor and the AO system to actively correct for telescope misalignment. All routine alignment and calibration procedures are automated via motorized stages that can be controlled from Python scripts. We present the current state of the WFC system as we prepare for final integration with the DKIST, including verification test design, system performance metrics, and laboratory test data.

Multi-conjugate adaptive optics (MCAO) has been proved to obtain the high resolution images with a large field of view in solar observation. A solar MCAO experiment system had been successfully developed and tested at the 1-meter New Vacuum Solar Telescope (NVST) of Fuxian Solar Observatory. It consists of two deformable mirrors (DMs), a multidirection Shack-Hartmann wavefront sensor (MD-WFS), and a real-time controller. In order to command the two DMs, five guide regions were selected from the MD-WFS to retrieve a three-dimensional measurement of the turbulent volume based on atmospheric tomography. This system saw the first light in October, 2017, and a series of MCAO-corrected high resolution sunspots images were acquired. In this presentation, the MCAO experiment system is introduced, and the observation results are presented. Furthermore, a new MCAO system based on our proposed MCAO configuration with a high order ground layer adaptive optics and low order high altitude correction will be developed for the NVST as a regularly operating instrument for scientific observations of the sun.

The Gemini Planet Imager Exoplanet Survey (GPIES) is a direct imaging campaign designed to search for new, young, self-luminous, giant exoplanet. To date, GPIES has observed nearly 500 targets, and generated over 30,000 individual exposures using its integral field spectrograph (IFS) instrument. The GPIES team has developed a campaign data system that includes a database incorporating all of the metadata collected along with all individual raw data products, including environmental conditions and instrument performance metrics. In addition to the raw data, the same database also indexes metadata associated with multiple levels of reduced data products, including contrast measures for individual images and combined image sequences, which serve as the primary metric of performance for the final science products. Finally, the database is used to track telemetry products from the GPI adaptive optics (AO) subsystem, and associate these with corresponding IFS data. Here, we discuss several data exploration and visualization projects enabled by the GPIES database. Of particular interest are any correlations between instrument performance (final contrast) and environmental or operating conditions. We show single and multiple-parameter fits of single-image and observing sequence contrast as functions of various seeing measures, and discuss automated outlier rejection and other fitting concerns. We also explore unsupervised learning techniques, and self-organizing maps, in particular, in order to produce lowdimensional mappings of the full metadata space, in order to provide new insights on how instrument performance may correlate with various factors. Supervised learning techniques are then employed in order to partition the space of raw (single image) to final (full sequence) contrast in order to better predict the value of the final data set from the first few completed observations. Finally, we discuss the particular features of the database design that aid in performing these analyses, and suggest potential future upgrades and refinements.

Knowledge of the point spread function (PSF) is critical to many astronomical science cases. However, the PSF can be very difficult to estimate for cases where there are many crowded point sources or for observations of extended objects. Additionally, for adaptive optics observations, the PSF can be very complex with both spatial and temporal variability in the PSF. Integral-field spectroscopy behind adaptive optics is especially challenging because the fields of view are typically too small to sample the halo for even a single PSF. Here, we present a method for semi-empirical PSF reconstruction for integral field spectrographs using a combination of point source observations on a parallel imager, instrumental aberration measurements, and atmospheric turbulence profiles. This work builds upon the PSF reconstruction project AIROPA designed for imaging and extending it to IFU work (AIROPA-IFU). By using empirical calibrators from the parallel imager, which has a much larger field of view, and accounting for anisoplantic effects and instrumental aberrations, we can predict the PSF on the spectrograph. An important aspect is being able to predict the PSF at many different wavelengths based on observations from broad-band imaging. Here, we discuss how science cases such as observations of stars at the Galactic center can benefit from this method. We also establish metrics to quantitatively assess the performance of PSF reconstruction. We show that for bright stars, AIROPA-IFU can produce spectra with signal to noise ratio 50% higher than with simple aperture extraction of a data cube.

We present on-sky results from the wide field ground-layer adaptive optics (GLAO) system on the University of Hawaii 2.2-meter telescope on Maunakea. We demonstrate improvements in image quality at visible wavelengths under a variety of seeing conditions. We discuss the gains for a variety of figures of merit including the full-width at half-maximum, the equivalent noise area, and the encircled energy diameter. These gains and figures of merit are discussed in the context of our GLAO science cases. In addition, we present the system image quality error budget, measurements of the dominant error terms, and their impact on the delivered focal plane images.

The Gemini Planet Imager (GPI), a coronagraphic adaptive optics instrument designed for spectroscopy of extrasolar planets, had first light in 2013. After five years, GPI has observed more than 500 stars, producing an extensive library of science images and associated telemetry that can be analyzed to determine performance predictors. We will present a summary of on-sky performance and lessons learned. The two most significant factors determining bright star contrast performance are atmospheric coherence time and the presence of dome seeing. With a possible move to Gemini North, we are planning potential upgrades including a pyramid-sensor based AO system with predictive control; we will summarize upgrade options and the science they would enable.

We review astronomical results in the visible (λ<1μm) with adaptive optics and note the status the MagAO system and the recent upgrade to visible camera’s Simultaneous/Spectra Differential Imager (SDI+) mode. Since mid- 2013 there has been a rapid increase visible AO with over 50 refereed science papers published in just 2015-2016 timeframe. Currently there are productive small (D < 2 m) visible light AO telescopes like the UV-LGS Robo-AO system (Baranec, et al. 2016). The largest (D=8m) telescope to achieve regular visible AO science is SPHERE/ZIMPOL. ZIMPOL is a polarimeter fed by the ~1.2 kHz SPHERE ExAO system (Fusco et al. 2016). ZIMPOL’s ability to differentiate scattered polarized light from starlight allows the sensitive detection of circumstellar disks, stellar surfaces, and envelopes of evolved AGB stars. The main focus of this paper is another large (D=6.5m Magellan telescope) AO system (MagAO) which has been very productive in the visible as well (particularly at the H−alpha emission line). MagAO is an advanced Adaptive Secondary Mirror (ASM) AO system at the Magellan in Chile. This ASM secondary has 585 actuators with < 1 msec response times (0.7 ms typically). MagAO utilizes a 1 kHz pyramid wavefront sensor (PWFS). The relatively small actuator pitch (~22 cm/subap, 300 modes, upgraded to 30 pix dia. PWFS) allows moderate Strehls to be obtained in the visible (0.63-1.05 microns). Long exposures (60s) achieve <30mas resolutions and 30% Strehls at 0.62 microns (r') with the VisAO camera (0.5-1.0 μm) in 0.5” seeing with bright R ≤ 9 mag stars (~10% Strehls can be obtained on fainter R~12 mag guide stars). Differential Spectral Imaging (SDI) at H-alpha has been very important for accreting exoplanet detection. There is also a 1-5micron science camera (Clio; Morzinski et al. 2016). These capabilities have led to over 35 MagAO refereed science publications. Here we review the key steps to having good performance in the visible and review the exciting new AO visible science opportunities and science results in the fields of: exoplanet detection; circumstellar and protoplanetary disks; young stars; AGB stars; emission line jets; and stellar surfaces. The recent rapid increase in the scientific publications and power of visible AO is due to the maturity of the next-generation of AO systems and our new ability probe circumstellar regions with very high (10-30 mas) spatial resolutions that would otherwise require much larger (<10m) diameter telescopes in the infrared.

This paper presents the overview of on-going and future adaptive optics (AO) activities at the Subaru telescope on the top of Maunakea in Hawaii. Currently, two AO systems are running at the Subaru telescope: AO188, a facility single-conjugate AO system with a bimorph deformable mirror and a curvature wavefront sensor with 188 elements, and SCExAO, an additional extreme AO system operating behind AO188 and specialized for exoplanet sciences. We recently started AO188 upgrade project to improve its performance for the next 5-10 years, which will also help improving SCExAO performance. These upgrades are in line with a development for the ULTIMATE-Subaru ground layer AO system.

Ground-layer adaptive optics (GLAO) systems offer the possibility of improving the ”seeing” of large ground-based telescopes and increasing the efficiency and sensitivity of observations over a wide field-of-view. We explore the utility and feasibility of deploying a GLAO system at the W. M. Keck Observatory in order to feed existing and future multi-object spectrographs and wide-field imagers. We also briefly summarize science cases spanning exoplanets to high-redshift galaxy evolution that would benefit from a Keck GLAO system. Initial simulations indicate that a Keck GLAO system would deliver a 1.5x and 2x improvement in FWHM at optical (500 nm) and infrared (1.5 μm), respectively. The infrared instrument, MOSFIRE, is ideally suited for a Keck GLAO feed in that it has excellent image quality and is on the telescope’s optical axis. However, it lacks an atmospheric dispersion compensator, which would limit the minimum usable slit size for long-exposure science cases. Similarly, while LRIS and DEIMOS may be able to accept a GLAO feed based on their internal image quality, they lack either an atmospheric dispersion compensator (DEIMOS) or flexure compensation (LRIS) to utilize narrower slits matched to the GLAO image quality. However, some science cases needing shorter exposures may still benefit from Keck GLAO and we will investigate the possibility of installing an ADC.

As space debris in lower Earth orbits are accumulating, techniques to lower the risk of space debris collisions must be developed. Within the context of the Space Environment Research Centre (SERC), the Australian National University (ANU) is developing an adaptive optics system for tracking and pushing space debris. The strategy is to pre-condition a laser launched from a 1.8 m telescope operated by Electro Optics Systems (EOS) on Mount Stromlo, Canberra and direct it at an object to perturb its orbit. Current progress towards implementing this experiment, which will ensure automated operation between the telescope and the adaptive optics system, will be presented.

Adaptive Optics (AO) systems aim at detecting and correcting for optical distortions induced by atmospheric turbulences. The Gemini Multi Conjugated AO System GeMS is operational and regularly used for science observations since 2013 delivering close to diffraction limit resolution over a large field of view. GeMS entered this year into a new era. The laser system has been upgraded from the old 50W Lockheed Martin Coherent Technologies (LMCT) pulsed laser to the Toptica 20/2W CW SodiumStar laser. The laser has been successfully commissioned and is now used regularly in operation. In this paper we first review the performance obtained with the instrument. I will go then into the details of the commissioning of the Toptica laser and show the improvements obtained in term of acquisition, stability, reliability and performance.

For the next generation of extremely large telescopes with the primary mirrors over 30 m in diameter, focal anisoplanatism renders single laser guide star AO useless. The laser tomography AO (LTAO) technique demonstrates an effective approach to reduce focal anisoplanatism, although it requires multiple LGSs & WFSs, and complex tomographic reconstruction. Here we propose a novel LGS alternative configuration with the corresponding wavefront sensing and reconstruction method, termed Projected Pupil Plane Pattern (PPPP). A key advantage of this method is that a single collimated beam is launched from the telescope primary mirror, and the wavefront sensed on the uplink path, which will not suffer from the effects of focal anisoplanatism. In addition, the power density of the laser beam is significantly reduced compared to a focused LGS, which decreases aircraft and satellite safety hazards. A laboratory experiment for PPPP has been setup to anchor the PPPP concept and compare against a Shack-Hartmann WFS.

In this work we discuss a mechanism for generation of a coherent source of light from the mesosphere as a new concept of directional laser guide star. In contrast to the near-isotropic spontaneous emission, nonlinear processes in atomic vapors like amplified spontaneous emission can yield highly directional emission in the forward and backward directions. Along with directional emission, excited sodium atoms also radiate at different wavelength creating a polychromatic laser guide star (PLGS). If feasible, a directional PLGS would provide a net gain in the return flux of several orders of magnitude compared to traditional LGS schemes, making possible laser-guided tip/tilt-correction in adaptive optic systems.

We report a 100-W continuous-wave (CW) 1178-nm narrowband polarization-maintaining (PM) Raman fiber amplifier (RFA) based on ESO’s patented RFA technology. A linearly-polarized 15-mW narrow-linewidth 1178-nm seed laser was amplified in a two-stage PM RFA counter-pumped by a PM 1120-nm fiber laser. Efficient suppression of stimulated Brillouin scattering (SBS) pushed the SBS threshold above 100 W. The Raman fiber types and lengths were chosen to maximize the Raman conversion efficiency in order to mitigate the thermal loads on critical optical components in the RFA. At 100 W of RFA output, which to the best of our knowledge is a record for such an RFA, the required 1120-nm pump laser power is only 180 W. Measurements of the linewidth of the amplified 1178-nm output at different power levels confirmed that the narrow linewidth of the 1178-nm seed laser is preserved even at 100 W of RFA output. The measured polarization extinction ratio (PER) at the 100-W level is > 24 dB, ensuring efficient second harmonic generation. Assuming a conservative conversion efficiency of ~ 80% by a resonant frequency doubler, narrow-linewidth CW guide star lasers with powers > 80 W at 589 nm can confidently be expected. The output spectrum measured at 100 W reveals that there is no risk of power migration from 1178 nm to the next Stokes order, which indicates that the RFA is still SBS-limited. With further optimization of the SBS suppression, it is expected that the RFA output power can be scaled beyond the current 100-W level.

A new type of sodium guidestar laser based on semiconductor laser technology is being developed by the astronomy, space, and laser communication communities in Australia and the United States, in partnership with laser manufacturer Arete Associates. Funding has been secured from the Australian Research Council and the Australian National University, with support from academic (UNSW) and industry partners (AAO, GMTO, EOS, Lockheed Martin). The consortium aims to develop a full scale prototype of the Semiconductor Guidestar Laser. The laser, to be delivered in 2019, will be initially installed on the EOS Satellite and Debris Tracking Station 1.8m telescope at Mount Stromlo Observatory where it will be thoroughly tested, on sky and in real operation conditions. This will be the first time that a Laser Guide Star is created in Australian skies. We present the project motivation and objectives, laser development and test plans, and the preliminary test results obtained to date.

Scientists at the Starfire Optical Range have been researching mesospheric sodium beacons for adaptive optics since 1992. Since then, we have developed four different sodium-wavelength lasers, all of which were based on diode-pumped, sum-frequency Nd:YAG oscillators. In 2016 we combined light from two commercial sodium-wavelength lasers, which use resonant-frequency doubling of light from a Raman fiber-amplifier, to form a single beacon. We used standard polarization techniques to combine the two lasers and produce a single beam with both left-hand and right-hand circularly polarized light. To avoid competitively pumping sodium atoms of the same velocity class, we tuned each of the lasers slightly off of the peak of the Doppler-broadened sodium line. However, the return flux from this beacon was lower than we expected, even when we accounted for the effect of detuning. In this paper, we propose an explanation for this phenomenon and show results from computer modeling and on-sky tests to support our claim. We believe the sodium atoms, which were optically pumped by the shorter-wavelength laser between the D2a F=2, m=+2 and F=3, m=+3 states, were down-pumped by the longer-wavelength laser to the D2b F=2, m=+2 and F=1, m=+1 states. Thus, these atoms were no longer available for optical pumping, which reduced the efficiency of the lasers in producing return flux. Addendum: We hope to show we can mitigate this effect by increasing re-pumping of the sodium D2b line on the shorter-wavelength laser.

As LGSs come from an excited cigar-shaped region in the sodium layer, they do not behave as point-like sources, therefore a new class of WFSs has been proposed to account for such elongation: the Ingot WFSs, the LGS-counterpart of a pyramid WFS. As they appear to be very promising, here we summarize the main reasons and goal of such a LGS-dedicated WFS and present the concept behind the code developed to produce numerical simulations, exploring the space of parameters. We report different approaches for the approximation of the extended source and the model adopted for the ingot prism simulation.

The Giant Magellan Telescope (GMT) wavefront control system will provide active optics control and optimized atmospheric turbulence correction to every instrument on the 25.4 m diameter GMT. All subsystems of the GMT wavefront control system have passed their preliminary design reviews, and several are now in the detailed design and prototyping phases. Significant progress has been made developing optimized control algorithms, and simulating observatory performance over a wide range of environmental conditions. We review the wavefront control strategy in each observing mode, and the associated image quality error budgets. We also describe recent d and prototyping progress, and our plans to complete the wavefront control system development and prepare for first light.

The Active optics, Guiding, and Wavefront Sensing system (AGWS), currently being designed by SAO, will use J-band dispersed fringe sensors (DFS) to phase the GMT to a fraction of an imaging wavelength. These phasing sensors will use off-axis guide stars to measure phase shifts at each of 12 segment boundaries. The fringes produced at each boundary will be dispersed in the perpendicular direction using an array of high-index doublet prisms. Inter-segment phase shifts will appear as tilts in the dispersed fringes, which can be measured in the Fourier domain. In order to avoid atmospheric blurring of the fringes, we require a J-band detector capable of fast, low-noise readout, which mandates the use of a SAPHIRA e-APD array. We built a DFS prototype that we tested on-sky at the Magellan Clay telescope behind the MagAO adaptive optics system in May 2018.

The TMT first light Adaptive Optics (AO) facility consists of the Narrow Field Infra-Red AO System (NFIRAOS), the associated Laser Guide Star Facility (LGSF) and the AO Executive Software (AOESW). 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 17-34 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, one high order Pyramid WFS for natural guide star AO, up to three low-order, IR, natural guide star on-instrument wavefront sensors (OIWFS) within each client instrument, and up to four guide windows on the science detectors (ODGW). 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, prototyping, fabricating and modeling the TMT first light AO systems and their components over the last two years. We will also report on a conceptual design study for an Adaptive Secondary Mirror for TMT.

The Planetary Systems Imager (PSI) is a modular instrument optimized for direct imaging and characterization of exoplanet and disks with the Thirty Meter Telescope (TMT). PSI will operate across a wide wavelength range (≈0.6 - 5μm) to image exoplanets and circumstellar disks in both reflected light and thermal emission. Thanks to the TMT’s large collecting area, PSI will have the sensitivity to directly image and spectrally characterize large gaseous planets with unprecedented sensitivity. PSI will also be capable of imaging rocky planets in the habitable zones of the nearest M-type stars in reflected light and search for biomarkers in their atmospheres. Imaging habitable planets in reflected light is PSI’s most challenging goal, requiring high contrast imaging (HCI) capabilities well beyond what current instruments achieve. This science goal drives PSI’s wavefront sensing and control requirements and defines the corresponding architecture discussed in this paper. We show that PSI must deliver 1e-5 image contrast ≈15 mas separation at λ ≈ 1μm-1.5μm, and that a conventional extreme-AO architecture relying on a single high speed wavefront sensor (WFS) is not sufficient to meet this requirement. We propose a wavefront control architecture relying on both visible light (λ < 1.1 μm) sensing to optimize sensitivity, and near-IR (λ > 1.1 μm) sensors to address wavefront chromaticity terms and provide high contrast imaging capability. We show that this combination will enable speckle halo suppression at the < 1e-5 raw contrast level in near-IR, allowing detection and spectroscopic characterization of potentially habitable exoplanets orbiting nearby M-type stars.

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.

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.

HARMONI is a visible and near-infrared integral field spectrograph, providing the ELT’s core spectroscopic capability. It will exploit the ELT’s scientific niche in its early years, starting at first light. To get the full sensitivity and spatial resolution gain, HARMONI will work at diffraction limited scales. This will be possible thanks to two adaptive optics systems, complementary to each other. The first one is a simple but efficient Single Conjugate AO system (good performance, low sky coverage), fully integrated in HARMONI itself. The second one is a Laser Tomographic AO system, providing a very high sky-coverage to the instrument. Both AO modes for HARMONI has gone through the Preliminary Design Review at the end of 2017, and will enter in Final Design phase from early 2018 to early 2020. In this paper, we present the results of the PDR and in particular the system choices that have been made for these SCAO and LTAO modules. We describe the strategy developed for the different Wave-Front Sensors: pyramid for SCAO, the LGSWFS concept, the NGSWFS path, and the truth sensor capabilities. We also detail a set of key items that have been addressed during the PDR, namely: The “Island effect” produced by the ELT segmented pupil, and how we plan to tackle it. The calibration strategy, including optical gain tracking, for the pyramid WFS The strategy for Non-Common Path Aberration (NCPA) calibration, and control The calibration strategy for the interaction matrices acquisition, and update during observations The impact of spot truncation for the LGSWFS, and the strategy developed to minimize the effect The jitter and telescope windshake strategy, and the computation of the corresponding sky coverage. Finally, we present the overall integration of the AO modules within the HARMONI instrument, and a full end-to-end simulation of the expected performance once at the Telescope.

MICADO is the European ELT first-light imager, working in the near-infrared at the telescope diffraction limit. Provided by MAORY, the ELT first-light adaptive optics module (AO), MCAO will be the primary AO mode of MICADO, driving the design of the instrument. MICADO will also come with a SCAO capability. Developed under MICADO’s responsibility and jointly by MICADO and MAORY, SCAO will be the first AO mode to be tested at the telescope, in a phased approach of the AO integration at the ELT. The MICADO-MAORY SCAO preliminary design review (PDR) will occur in November 2018. We present here different activities and results we have had in the past two years preparing this PDR, covering several fields (opto-mechanics, electronics, real-time and control software, integration and tests, AO simulations and performance, prototyping) and the different SCAO subsystems (pyramid wavefront sensor, calibration unit, real-time computer, dichroic and the so-called Green Doughnut which hosts the SCAO assembly as well as the MAORY MCAO natural guide star wavefront sensors).

METIS is the Mid-infrared Extremely large Telescope Imager and Spectrograph, one of the first generation instruments of ESO’s 39m ELT. All scientific observing modes of METIS require adaptive optics (AO) correction close to the diffraction limit. Demanding constraints are introduced by the foreseen coronagraphy modes, which require highest angular resolution and PSF stability. Further design drivers for METIS and its AO system are imposed by the wavelength regime: observations in the thermal infrared require an elaborate thermal, baffling and masking concept. METIS will be equipped with a Single-Conjugate Adaptive Optics (SCAO) system. An integral part of the instrument is the SCAO module. It will host a pyramid type wavefront sensor, operating in the near-IR and located inside the cryogenic environment of the METIS instrument. The wavefront control loop as well as secondary control tasks will be realized within the AO Control System, as part of the instrument. Its main actuators will be the adaptive quaternary mirror and the field stabilization mirror of the ELT. In this paper we report on the phase B design work for the METIS SCAO system; the opto-mechanical design of the SCAO module as well as the control loop concepts and analyses. Simulations were carried out to address a number of important aspects, such as the impact of the fragmented pupil of the ELT on wavefront reconstruction. The trade-off that led to the decision for a pyramid wavefront sensor will be explained, as well as the additional control tasks such as pupil stabilization and compensation of non-common path aberrations.

We give a status report, a project schedule and an overview of the Adaptive Optics (AO) and Multi-conjugate Adaptive Optics (MCAO) system of the upcoming 4m European Solar Telescope (EST) including the science requirements. The pros and cons of the possible wavefront sensor concepts are discussed, as well as the require- ments for the numerical simulation tools.

MOSAIC is a mixed-mode multiple object spectrograph planned for the ELT that uses a tiled focal plane to support a variety of observing modes. The MOSAIC AO system uses 4 LGS WFS and up to 4 NGS WFS positioned anywhere within the full 10 arcminute ELT field of view to control either the ELT M4/5 alone for GLAO operation feeding up to 200 targets in the focal plane, or M4/5 in conjunction with 10 open-loop DMs for MOAO correction. In this paper we present the overall design and performance of the MOSAIC GLAO and MOAO systems.

The Real-Time Controller (RTC) for the Thirty Meter Telescope (TMT) Narrow Field Infrared Adaptive Optics System (NFIRAOS) is the software and server hardware that converts wavefront error measurements into wavefront corrector demands, at the heart of the laser guide star multi-conjugate adaptive optics (MCAO) or natural guide star adaptive optics (NGS AO). The RTC takes input from up to six Shack-Hartmann Laser Guide Star wavefront sensors (LGS WFS), one high-order Natural Guide Star Pyramid Wavefront Sensor (PWFS), up to three Shack-Hartmann On-Instrument wavefront sensors (OIWFS) that are located in the client science instruments, and up to 4 on-detector guide windows (ODGW) also in the client instruments. The RTC controls two deformable mirrors conjugated to 0km (DM0) and 11.8km (DM11). DM0 is mounted on a tip/tilt stage (TTS). During the final design phase we performed prototyping to verify that off-the-shelf servers using general purpose CPUs are able to support the maximum 800 Hz frequency at which the RTC is required to operate. We also considered methods to provide live data streams to a graphical user interface without impacting the AO system performance. This paper will discusses the outcome of the impact of jitter and latency on loop speed in our prototype and an overview of the RTC pipeline, including the many “knobs” that can be turned to fine-tune the behavior of NFIRAOS in different observing modes, and under different observing conditions.

The Green Flash initiative responds to a critical challenge in the astronomical community. Scaling up the real-time control solutions of AO instruments in operation to the specifications of the AO modules at the core of the next generation of extremely large telescopes is not a viable option. The main goal of this project is to design and build a prototype for an AO RTC targeting the E-ELT first-light AO instrumentation. We have proposed innovative technical solutions based on emerging technologies in High Performance Computing, assessed this enabling technologies through prototyping and are now assembling a full scale demonstrator to be validated with a simulator and eventually tested on sky. In this paper, we report on downselection process that led us to the final prototype architecture and the performance of our full scale prototype obtained with a real-time simulator.

With the next-generation of Extremely Large Telescopes (ELTs), the demands of adaptive optics real-time control (AO RTC) increase massively compared to the most complex AO systems in use today. Green Flash, an ongoing EU funded project, is investigating the optimal architecture for ELT scale AO RTC, with an emphasis on GPU and many core CPU solutions. The Intel Xeon Phi range of x86 CPUs is our current focus of investigation into CPU technologies to solve the ELT-scale AO RTC problem. Built using Intels Many Integrated Core (MIC) architecture incorporating 64 general purpose x86 CPU cores into a single CPU package paired with a large pool of on-chip high bandwidth MCDRAM, the Xeon Phi includes many of the advantages of current technologies. The current generation Xeon Phi is readily compatible with standard Linux operating systems and all of the tools and libraries, and as a standard socketed CPU it eliminates the latency introduced by the extra data transfers required for previous Xeon Phis and other accelerator devices. The Durham Adaptive Optics Real-time Controller (DARC) is a freely available, on-sky tested, fully modular, x86 CPU based AO RTC which which is ideally suited to be a basis for our investigation into ELT scale AO RTC performance. We present a proof of concept AO RTC system, in collaboration with the Green Flash project, for ELT scale MCAO, with the requirements of the MAORY AO system in mind, using an optimised DARC on Xeon Phi hardware to achieve the required performance.

The paper describes the possible implementation of a calibration source to be installed in the ELT optical train providing a single pass test beam for AO systems calibration. The source could be used by SCAO systems like those of MICADO/MAORY, HARMONI and METIS and to monitor M4 shape and differential pistons. Additional functionalities could be provided in order to use it for LGS based AO systems calibrations like the MCAO system of MAORY/MICADO or the foreseen LTAO system of HARMONI. In this work, we show a straw man optical design for such an on-axis source and describe options to provide off-axis sources to support engineering and commissioning phases of AO systems at the ELT.

Multi-Conjugate Adaptive Optics (MCAO) systems aim at correcting for the atmospheric turbulence uniformly over wide-field observations. Compared to classical AO, this requires a tomographic reconstruction of the turbulence perturbations, that is to say a reconstruction of the atmosphere in its volume, and the control of several deformable mirrors optically conjugated to various altitudes. During the last two decades, many tomographic reconstructors have been proposed in the AO literature and some have been implemented on sky on existing MCAO systems. This paper presents an overview of MCAO reconstructors. Four categories of reconstructors are considered: i) the reconstructors based on interaction matrix; ii) the minimum-variance static reconstructors; iii) the 3-step recontructors and iv) the Kalman-based reconstructors. We discuss their relative advantages and drawbacks.

In the design of the future generation ELTs the support structures for the secondary mirror (also known as spiders) lead to a piston on each of the pupil segments created by the spiders, known as ”island effect”. In this talk we focus on fast and stable reconstruction methods to cope with the island effect. We present and compare wavefront reconstruction algorithms and highlight their performance in a METIS- like AO system. We focus on FEWHA (Finite Element-Wavelet Hybrid Algorithm), Poke Matrix Inversion using a set of predefined DM influence functions and new methods for a direct segment piston estimation in combination with the P-CuReD (Preprocessed Cumulative Reconstructor with Domain decomposition). The results are backed up by Octopus (the full AO end-to-end simulator from ESO) simulations highlighting stable Strehl ratios for our simulation setting.

The compute and control for adaptive optics (cacao) package is an open-source modular software environment for real-time control of modern adaptive optics system. By leveraging many-core CPU and GPU hardware, it can scale up to meet the demanding computing requirements of current and future high frame rate, high actuator count adaptive optics (AO) systems. cacao’s modular design enables both simple/barebone operation, and complex full-featured AO control systems. cacao’s design is centered on data streams that hold real-time data in shared memory along with a synchronization mechanism for computing processes. Users and programmers can add additional features by coding modules that interact with cacao’s data stream format. We describe cacao’s architecture and its design approach. We show that accurate timing knowledge is key to many of cacao’s advanced operation modes. We discuss current and future development priorities, including support for machine learning to provide real-time optimization of complex AO systems.

While deep learning has led to breakthroughs in many areas of computer science, its power has yet to be fully exploited in the area of adaptive optics (AO) and astronomy as a whole. In this paper we describe the first steps taken to apply deep, convolutional neural networks to the problem of wavefront reconstruction and prediction and demonstrate their feasibility of use in simulation. Our preliminary results show we are able to reconstruct wavefronts comparably well to current state of the art methods. We further demonstrate the ability to predict future wavefronts up to five simulation steps with under 1nm RMS wavefront error.

The long commissioning of the Adaptive Optics Facility (AOF) project has been completed shortly after this conference, providing AO correction to two Very Large Telescope (VLT) foci supported by an adaptive secondary mirror and four laser guide stars. Four AO modes are delivered: a Single Conjugate AO (SCAO) system for commissioning purpose, wide field and medium field Ground Layer AO (GLAO) for seeing improvement and narrow field Laser Tomography AO (LTAO) for ultimate performance. This paper intends to describe the implemented AO baseline and to highlight the most relevant results and lessons learned. In particular, it will address the control and reconstruction strategy, the wavefront sensing baseline and the online telemetry used to optimize the system online, estimate the turbulence profile and calibrate the misregistrations. Focusing on the LTAO mode, we will describe the tomography optimization, by exploring the reconstruction parameter space. Finally, on sky performance results will be presented both in terms of strehl ratio and limiting magnitude.

The performance of closed-loop tilt-control and adaptive-optics systems suffers when conditions change. Examples of changing conditions are angular extent of the object, signal-to-noise ratio, and characteristics of the disturbance. A simple learning algorithm motivated by neural network theory is developed to change the closed-loop gain in real-time to adapt quickly to changing conditions. This technique finds the correct loop gain within seconds with no operator intervention, which saves several minutes for each observation. Simulation and experimental results show improvement for both tilt-control and adaptive-optics systems.

Themis is a 90 cm solar telescope which undergoes a rejuvenation of its scientific instruments. In particular, it is about to be equipped with an adaptive optics (AO) system with a bandwidth of at least 1 kHz and featuring a 97 actuator deformable mirror and 10×10 Shack-Hartmann wavefront sensor. Nowadays, the computational power required by such a system can be provided by current multi-core CPU. We have therefore implemented from scratch the real-time control system in pure software using Julia,¹ a new language for technical computations, and running on Linux OS. Our main motivation was to be able to exploit new advances in wavefront sensing and adaptive optics control.

With a computational cost comparable to state-of-the-art but sub-optimal methods used in solar AO, our wavefront sensing algorithm estimates the local slopes and their covariances following a maximum likelihood registration method.

Themis AO system has a modest size but can be used to assert the benefits of maximum a posteriori (MAP) wavefront sensing and control,^{2, 3} of accounting of the covariances of the measure and of the temporal correlation of the turbulent wavefront.

The progress achieved in implementing Point Spread Function reconstruction (PSF-R) capability at W. M. Keck Observatory (WMKO) is discussed. Observations of low-mass binary systems have been used to evaluate the improvements in astrometry and photometry using reconstructed PSFs. The on-sky performance of PSF-R is discussed by comparing the binary-fitting analysis using the reconstructed PSFs with the standard methods. We show that the PSFR in the NGS provides comparable performance to having a close reference star in the imaging science instrument. The on-sky troubleshooting efforts and the recent PSF-R technical developments are also presented. We find that the PSF-R reconstruction is more of a systems science problem that a post-processing problem. We close by discussing the lessons learned in the context of existing and future extremely large telescopes.

GIRMOS is a new concept for a Multi-Object Adaptive Optics (MOAO) spectrograph for Gemini (commissioning in 2023). We present an overview of the GIRMOS-MOAO conceptual design and simulation results. This instrument will become a facility instrument at Gemini and carry out scientific follow-up for JWST, but will also act as a Thirty-Meter Telescope (TMT) pathfinder, laying the scientific and technical ground-work for developing a second generation instrument for TMT. Technical Innovations for GIRMOS include a modular, high performance MOAO system, and high throughput infrared imaging spectroscopy. These technological innovations will have the broadest impact in the study of the formation and evolution of galaxies, but will also have broad reach in fields such as star and planet formation within our Milky Way and supermassive black holes in nearby galaxies. The MOAO system will patrol the 2' field of regard of GeMS, and utilize 16×16 actuator DMs feeding 4 IFU spectrographs, to yield diffraction limited performance with a goal of 50% Strehl at H-band.

We present the development and testing of focal plane wavefront control techniques that utilize microwave kinetic inductance detectors (MKIDs) as a focal plane IFU. MKIDs are ideally suited to this application, as they are energy resolving, and have single photon sensitivity, zero read noise, and microsecond time resolution. These characteristics enable much higher feedback rates than conventional systems; for the first time, focal plane measurements may be used to correct atmospheric aberrations in addition to quasistatics. A variety of approaches are under development, including conventional speckle nulling, as well as more advanced approaches such as linear dark field control. We have developed an MKID-specific speckle nulling code for DARKNESS, a 10,000 pixel MKID IFU behind the stellar double coronagraph (SDC) and PALM-3000 (P3K) AO system at Palomar observatory. Our code implements the algorithm described in (Bottom, et. al, 2016) with minor modifications. To facilitate high feedback rates on sky, the code is optimized for computational speed, and implements low-latency communications to both P3K and the MKID readout. It is also capable of integrating with P3K in closed loop operation. Using our code, we have demonstrated quasi-static speckle nulling at a 1 Hz feedback rate in the laboratory. We hope to demonstrate rates ~10-100 Hz in the near future. In addition to continuing our work with DARKNESS, we will adapt our code to MEC, a 20,000 pixel MKID IFU behind the Subaru coronagraphic extreme adaptive optics system (SCExAO) at Subaru observatory. MEC is scheduled to commission in January 2018.

Geared by the increasing need for enhanced performance, both optical and computational, new dynamic control laws have been researched in recent years for next generation adaptive optics systems on current 10 m-class and extremely large telescopes up to 40 m. We provide an overview of these developments and point out prospects to making such controllers drive actual systems on-sky.

The performance of high-contrast AO instruments (GPI, SPHERE, ScEXAO, MagAO) and other systems that operate at visible wavelengths can be severely hampered by control system latencies and temporal wavefront errors. In high-contrast systems, temporal errors and delays are manifest as high spatial frequency wavefront residuals that scatter light into the controllable region of the PSF and diminish contrast, an effect that is particularly severe when atmospheric coherence times are short. Solutions that have been proposed include lower latency electronics, deformable mirrors with lower mechanical response times, and specialized control algorithms such as predictive control. These advancements will be necessary for achieving the latency goals of high actuator count systems on future Extremely Large Telescopes (ELTs), including NFIRAOS+ and PFI on the Thirty Meter Telescope, upgrading the performance of existing highcontrast systems, and pushing adaptive optics to visible wavelengths. LLAMAS (Low-Latency Adaptive Optical Mirror System) is a fully funded adaptive optics system at the Lawrence Livermore National Laboratory site that will test these techniques in an integrated, real time, closed-loop AO system. With a total system latency goal of ~100 microseconds (including mechanical response time, not including frame integration), LLAMAS will achieve an order of magnitude improvement in AO system latencies over the current generation of high-contrast AO systems. The woofer/tweeter architecture will incorporate a 492-actuator Boston Micromachines MEMS device mapping 24 actuators across a circular pupil. The tweeter mirror will be paired with a specialized low-latency driver, delivering less than 40 microseconds electronic and mechanical latency (10 – 90%). The real-time control computer will utilize the computationally efficient Fourier Transform Reconstructor with a predictive Kalman filter with a goal of completing all computations and reconstructing the wavefront in less than 20 microseconds. LLAMAS will be fully integrated with a 21×21 lenslet Shack-Hartmann sensor by January 2019. These proceedings describe the LLAMAS design, characterize the performance of its low-latency componentry, and discuss the relevance of the design for future high-contrast, visiblelight, and high actuator count AO systems on ELTs.

The integral field spectrograph OSIRIS at Keck I has been used to measure the motion of the stars around the supermassive black hole at the Center of the Galaxy. The small field of view provided and the crowding of the region prevent any good PSF estimate. A parallel imager can be used simultaneously to the IFU. However, its distance of 19 arcseconds prevents the observed PSF to be directly applied to the IFU because of anisoplanatism and instrumental aberrations. The Galactic Center Group at UCLA has developed an algorithms to predict PSF variability for Keck AO images (Off-axis PSF reconstruction, AIROPA software package). AIROPA allows us to use the parallel imager to correctly predict the IFU’s PSF. We modified this package to adapt it to the case of OSIRIS imager and IFU (AIROPA-IFU) and characterized the instrumental aberrations of both detectors. Here, we present preliminary results of the application of this post-processing tool to OSIRIS datasets of the Galactic Center.

The aim of the Spectro-Polarimetric High-contrast Exoplanet Research (SPHERE) instrument is to detect extremely faint astronomical sources (i.e., giant extra-solar planets, disks etc …) in the vicinity of bright stars. The detection capabilities of an exoplanet hunter are largely controlled by its adaptive optics (AO) system. Better AO correction provides improved coronagraph extinction and fewer starlight residuals. The challenging SPHERE science goals require a very high performance AO system to feed a quasi-perfect flat wave front, corrected for atmospheric turbulence and internal defects, to the scientific instruments. In May 2014 SPHERE was installed on the third unit telescope (Melipal) of the Very Large Telescope (VLT) in Chile. The results obtained over 3 years of operations essentially nicely confirm the AO predictions made at the time of the design phase and the corresponding performance budget analysis to cover various operation conditions in terms of target brightness and turbulence conditions. This is a strong basis to propose a realistic SPHERE AO upgrade. The SPHERE upgrade project intends to push the ultimate performance of SPHERE in terms of both final contrast and sensitivity (especially towards redder and fainter stars), thus allowing to address new science cases and to offer new detection or characterisation modes such as the coupling with high spectral resolution spectrographs, either in the infrared or in the visible. To do so, we have to address several tasks: • The main AO loop has to be accelerated (up to 3 kHz) and efficient predictive control laws have to be implemented in order to significantly reduce the temporal effects; • The main wave front sensor scheme has to be revisited in order to make the system more sensitive and make possible to work on very red stars. It will be achieved by adding to the current Visible Spatially Filtered Shack-Hartman an IR-Pyramid counterpart; • The NCPA correction and the system ability to create and stabilize dark-hole during an entire observation block has to be developed in order to get rid of the residual quasi-static speckles and residual diffraction patterns. This will be done thanks to the combination of very accurate coronagraphic wave front sensors (COFFEE and ZELDA). This presentation will detail the various system studies and trade-off choices which have led to the new concept of the SPHERE upgrade. A preliminary design of the new AO loop and its main components (IR pyramid, RTC, post-coronographic WFS) will be presented. We will show that the proposed SPHERE upgrade development can be achieved in a timely manner without affecting the current SPHERE configuration and for a reasonable cost. Finally, an AIT concept minimizing the down-time of the instrument will be described. At each stage of the project, special attention will be paid to ensure that the initial capabilities and performance of SPHERE are not be jeopardized by the proposed SPHERE upgrade developments.

The SPHERE instrument, dedicated to high contrast imaging on VLT, has been routinely operated for more than 3 years, over a large range of conditions and producing observations from visible to NIR. A central part of the instrument is the high order adaptive optics system, named SAXO, designed to deliver high Strehl image quality with a balanced performance budget for bright stars up to magnitude R=9. We take benefit now from the very large set of observations to revisit the assumptions and analysis made at the time of the design phase: we compare the actual AO behavior as a function of expectations. The data set consists of the science detector data, for both coronagraphic images and non-coronagraphic PSF calibrations, but also of AO internal data from the high frequency sensors and statistics computations from the real-time computer which are systematically archived, and finally of environmental data, monitored at VLT level. This work is supported and made possible by the SPHERE « Data Center » infrastructure hosted at Grenoble which provides an efficient access and the capability for the homogeneous analysis of this large and statistically-relevant data set. We review in a statistical manner the actual AO performance as a function of external conditions for different regimes and we discuss the possible performance metrics, either derived from AO internal data or directly from the high contrast images. We quantify the dependency of the actual performance on the most relevant environmental parameters. By comparison to earlier expectations, we conclude on the reliability of the usual AO modeling. We propose some practical criteria to optimize the queue scheduling and the expression of observer requirements ; finally, we revisit what could be the most important AO specifications for future high contrast imagers as a function of the primary science goals, the targets and the turbulence properties.

Spectroscopy of exoplanets can potentially detect biomarkers in habitable planets around other stars. The high dispersion coronagraphy (HDC) technique provides a pathway to search for biomarkers in planets around M dwarfs with next-generation ground-based extremely large telescopes (ELTs). The HDC consists of a coronagraph operating behind an extreme adaptive optics (AO) system, a single-mode fiber injection unit, and a high resolution spectrometer (HRS). The coronagraph spatially filters out starlight while the HRS spectrally discriminates starlight from planet light, reaching a starlight suppression level that enables biomarker detection. I will simulating ELT HDC instrument performance as a function of wavelength, spectral resolution, starlight suppression, and planet types, considering realistic noise budget that includes speckle noise, thermal and sky background and exozodical background.

The Integrated Optical System (IOS) is an extreme adaptive optics system designed for NASA’s Laser Com- munication Relay Demonstration mission. There is a great deal of overlap between the requirements for laser communication AO and high-contrast exoplanet imaging AO systems. Both require very high Strehl ratios with narrow fields of view. This overlap allows the IOS to serve as a testbed and technology demonstrator for astronomical extreme adaptive optics systems.

There are several example technologies from the IOS that are already making the transition to astronomical AO systems. The first is that the real time controller based on Direct Memory Access transfer between the WFS camera link frame-grabber and a DSP board is being reused on the upgrade to PALM-3000 AO system at Palomar Observatory. This enables the system to minimize latency by bypassing the CPU and its inherent timing jitter. Technologies like this will be crucial to enabling high contrast imaging on the next generation of extremely large telescopes. In addition, the IOS measures Fried’s parameter from wavefraont measures in near real time. This technology has already been deployed to PALM-3000. The main function of Laser Communication AO systems is to couple the incoming light into single mode fiber. This is the same configuration that will be used by AO coupled radial velocity spectrographs.

The adaptive optics system is a woofer/tweeter design, with one deformable mirror correcting for low spatial frequencies with large amplitude and a second deformable mirror correcting for high spatial frequencies with small amplitude. The system uses a Shack-Hartmann wavefront sensor. The system has achieved first light and is undergoing commissioning. We will present an overview of the system design and initial performance.

The Magellan extreme adaptive optics (MagAO-X) instrument is a new extreme adaptive optics (ExAO) system designed for operation in the visible to near-IR which will deliver high contrast-imaging capabilities. The main AO system will be driven by a pyramid wavefront sensor (PyWFS); however, to mitigate the impact of quasi-static and non-common path (NCP) aberrations, focal plane wavefront sensing (FPWFS) in the form of low-order wavefront sensing (LOWFS) and spatial linear dark field control (LDFC) will be employed behind a vector apodizing phase plate (vAPP) coronagraph using rejected starlight at an intermediate focal plane. These techniques will allow for continuous high-contrast imaging performance at the raw contrast level delivered by the vAPP coronagraph ( 6 x 10^-5). We present simulation results for LOWFS and spatial LDFC with a vAPP coronagraph, as well as laboratory results for both algorithms implemented with a vAPP coronagraph at the University of Arizona Extreme Wavefront Control Lab.

The Optimal Optical Coronagraph (OOC) Workshop held at the Lorentz Center in September 2017 in Leiden, the Netherlands, gathered a diverse group of 25 researchers working on exoplanet instrumentation to stimulate the emergence and sharing of new ideas. In this second installment of a series of three papers summarizing the outcomes of the OOC workshop, we present an overview of common path wavefront sensing/control and Coherent Differential Imaging techniques, highlight the latest results, and expose their relative strengths and weaknesses. We layout critical milestones for the field with the aim of enhancing future ground/space based high contrast imaging platforms. Techniques like these will help to bridge the daunting contrast gap required to image a terrestrial planet in the zone where it can retain liquid water, in reflected light around a G type star from space.

Infrared wavefront sensors are now implemented in MCAO systems as reference (or truth sensors). After the successful development of C-RED One, the only commercial 320×256 3500 fps e-APD sub-e noise infrared camera, First Light Imaging developed the C-RED 2 InGaAs 640×512 fast camera with unprecedented performances in terms of noise, dark and readout speed based on the SNAKE SWIR detector from Sofradir. The C-RED 2 characteristics and performances at 600 fps are fully described in this paper. The C-RED2 development is supported by the "Investments in the future" program and the Provence Alpes Côte d'Azur Region, in the frame of the CPER.

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.

Six Laser Guide Stars (LGS) are included in the design of the European Extremely Large Telescope (ELT), with all of its current instruments taking advantage of them using Shack-Hartmann (SH) wavefront sensors (WFS). However, this implementation raises new issues related to the unprecedented elongation that results from the perspective effect combined to the thickness of the sodium layer. In order to investigate wavefront sensing with an elongated LGS on a SH WFS, we are taking advantage of the presence of the multi-object adaptive optics demonstrator CANARY on the William Herschel Telescope (WHT), in La Palma island, that was upgraded with a sodium LGS WFS for our experiment. The LGS is generated by ESO’s transportable Wendelstein LGS unit and the elongation is obtained by positioning the laser launch telescope 40 meters away from the WHT. With this experiment we are able to measure wavefronts using an elongated LGS WFS. In this paper, we present results obtained during the latest run of observations in September 2017. In these results is comprised an error breakdown of wavefront measurement on elongated LGS. The performances of several centroiding methods are compared thanks to this error breakdown. Additionally, we take advantage of varying observation conditions with respect to seeing and sodium profile to establish the robustness of the different centroiding methods. Finally, these performances are evaluated for different SH designs, to explore which compromises can be reached with respect to pixel scale and sub-aperture field of view.

MAORY will be the multi-adaptive optics module feeding the high resolution camera and spectrograph MICADO at the Extremely Large Telescope (ELT) first light. In order to ensure high and homogeneous image quality over the MICADO field of view and high sky coverage, the baseline is to operate wavefront sensing using six Sodium Laser Guide Stars. The Laser Guide Star Wavefront Sensor (LGS WFS) is the MAORY sub-system devoted to real-time measurement of the high order wavefront distortions. In this paper we describe the MAORY LGS WFS current design, including opto-mechanics, trade-offs and possible future improvements.

Wavefront sensing in the infrared is highly desirable for the study of M-type stars and cool red objects, as they are sufficiently bright in the infrared to be used as the adaptive optics guide star. This aids in high contrast imaging, particularly for low mass stars where the star-to-planet brightness ratio is reduced. Here we discuss the combination of infrared detector technology with the highly sensitive Pyramid wavefront sensor (WFS) for a new generation of systems. Such sensors can extend the capabilities of current telescopes and meet the requirements for future instruments, such as those proposed for the giant segmented mirror telescopes. Here we introduce the infrared Pyramid WFS and discuss the advantages and challenges of this sensor. We present a new infrared Pyramid WFS for Keck, a key sub-system of the Keck Planet Imager and Characterizer (KPIC). The design, integration and testing is reported on, with a focus on the characterization of the SAPHIRA detector used to provide the H-band wavefront sensing. Initial results demonstrate a required effective read noise <1e^– at high gain.

Extremely Large Telescopes are making Pyramid Wavefront Sensors (PWFS) the preferred engineering choice for Adaptive Optics designs, such as the MICADO camera SCAO subsystem currently developed at LESIA. A major PWFS issue is the so-called Optical Gain (OG) effect: PWFSs experience a nonlinearity-induced sensitivity reduction – of 60% or worse at the fitting error on standard atmospheric conditions – which degrades as the turbulence residual increases. OG affects system performance, jeopardizes loop stability and prevents efficient non-common path aberration compensation. We investigate a modal approach to OG impact mitigation, and investigate its impact on nonlinearity error depending on the AO control basis. We evidence that scalar gain compensation of the OG is insufficient on high order systems, as the high spatial frequency range spanned covers high OG value discrepancies over the controlled basis. We quantify the performance improvements obtained with OG modal compensation by end-to-end numerical simulations. Finally, we propose a modelization of OG modal compensation coefficients, in order to allow their computation on-the-fly provided telemetry of the immediate turbulence conditions is available.

Adaptive optics systems correct atmospheric turbulence in real time. Most adaptive optics systems used routinely correct in the near infrared, at wavelengths greater than 1 μm. MagAO- X is a new extreme adaptive optics (ExAO) instrument that will offer corrections at visible-to- near-IR wavelengths. MagAO-X will achieve Strehl ratios of ≥70% at Hα when running the 2040 actuator deformable mirror at 3.6 kHz. A visible pyramid wavefront sensor (PWFS) optimized for sensing at 600-1000 nm wavelengths will provide the high-order wavefront sensing on MagAO-X. We present the optical design and predicted performance of the MagAO-X pyramid wavefront sensor.

As already noticed in other telescopes, the presence of large telescope spiders and of a segmented deformable mirror in an Adaptive Optics system leads to pupil fragmentation and may create phase discontinuities. On the ELT telescope, a typical effect is the differential piston, where all disconnected areas of the pupil create their own piston, unseen locally but drastically degrading the final image quality. The poor sensitivity of the Pyramid WFS to differential piston will lead to these modes been badly seen and therefore badly controlled by the adaptive optics (AO) loop. In close loop operation, differential pistons between segments will start to appear and settle around integer values of the average sensing wavelength. These additional differential pistons are artificially injected by the adaptive optics control loop but do not have any real physical origin, contrary to the Low Wind Effect. In an attempt to reduce the impact of unwanted differential pistons that are injected by the AO loop, we propose a novel approach based on the pair-wise coupling of the actuators sitting on the edges of the deformable mirror segments. In this paper, we present the correction principle, its performance in nominal seeing condition, and its robustness relative to changing seeing conditions, wind speed and natural guide star magnitude. We show that the edge actuator coupling is a simple and robust solution and that the additional quadratic error relative to the reference case (i.e. no spiders) is of only 40 nm RMS, well within the requirements for HARMONI.

The Leiden EXoplanet Instrument (LEXI) is a bench-mounted high-contrast spectrograph (HCS) and high- contrast imager(HCI). Both science instruments are mounted behind a common adaptive optics (AO) system. The AO can be controlled by several new wavefront sensors for which we will show the first on-sky results. There is a new pupil-plane wavefront sensors; the Generalized Optical Differentiation Wavefront sensor(g-ODWFS). LEXI can switch between two observing modes, the HCI mode or the HD-IFS mode. The spectrograph is very compact because it is fed by single-mode fiber. The HD-IFS is an IFS that covers the spectral range of 600 800 nm with a constant spectral resolving power of 96000. The 2kx3k detector makes it possible to deliver diffraction limited spectra of up to 20 input fibers. The high-dispersion spectra of the HD-IFS allow for robust post-processing technique to remove residual stellar speckles and allows for direct characterization of the faint stellar environment. We will show the first sucesful on-sky results of the injection into a single-mode fiber with LEXI. In HCI mode an Apodizing Phase Plate (APP) is used to create a dark region around the star with an average design contrast of 1E-4. The APP is multiplexed with holographic modes to create the Coronagraphic Modal Wavefront sensor (cMWS) for non-common path error (NCPE) correction. The cMWS creates holographic copies in the focal plane that react linearly to aberrations. The holographic copies are measured simultaneously with the science target. There is no downtime for NCPE correction. We will show the first on-sky closed-loop correction of (NCPEs) with the cMWS.

We report on the conceptual design study done for the Ground Layer Adaptive Optics system of the ULTIMATE-Subaru project. This is an ambitious instrument project, providing GLAO correction in a square field of view of 14 arcmin on a side, aiming to deliver improved seeing at the near infrared wavelength. Its client instruments are an imager and multi-IFU spectrograph at Cassegrain and a Multi-Object spectrograph at Nasmyth. In this paper, we introduce the ULTIMATE-Subaru project overview and its science case and report the results of the GLAO performance prediction based on the numerical simulation and conceptual design of the wavefront sensor system.

CANARY is a wide-field AO on-sky test facility which has been operated annually on the 4.2m William Herschel Telescope since 2010. CANARY has the stated goal of testing and demonstrating AO technologies that are critical for ELT AO performance. It has seen four distinct phases where new AO technologies have been developed and demonstrated, including NGS MOAO in 2010 (phase A), Rayleigh LGS and NGS MOAO in 2012 and 2013 (phase B, with LGS commissioning in 2011), LTAO operation in 2014 and 2015, and finally operation with a single Sodium laser guide star launched far off axis in 2016 and 2017 (phase D). By launching this laser guide star 40m off axis, extremely elongated laser guide star spots are created in the CANARY LGS Shack-Hartmann wavefront sensor. Therefore, the 7×7 sub-apertures of CANARY can be used to test wavefront sensing performance of a sub-pupil of the ELT located furthest from the laser launch axis. We present an overview of CANARY in its phase D configuration. Depending on where in the sky the LGS is pointing, the projected baseline between the on-axis LGS wavefront sensor and the laser launch location, as seen by the wavefront sensor, will vary from about 20-40m, allowing us to artificially generate different degrees of elongation. Additionally, the well sampled CANARY sub-apertures have 30×30 pixels each and a 20 arcsecond field of view, using an OCAM2S EMCCD camera. This means that by shrinking sub-apertures, and optionally by binning pixels, we are able to investigate different pixel scales and fields of view for the ELT systems, thus determining the optimal design parameters. Here we discuss the closed loop tests that were performed to investigate the effect of spot truncation and extreme elongation. We include different correlation techniques, including standard FFT-based correlation, brute force correlation and correlation by difference squared. We also mention dynamic and automatic updates of the correlation reference images while the AO loop is engaged that have previously been reported. The matched filter algorithm is also mentioned, with a pointer to our prior on-sky investigations. We give our recommendation for the ELT wavefront sensing algorithm of choice, and our evidence based reasons for this recommendation, which may come as a surprise to some. Finally we also present the future experiments to be performed with CANARY, give details of the OPTICON funded programme which enables the hosting of AO experiments on CANARY, allowing the AO community to get involved.

The MCAO pathfinder Clear on the 1.6-meter Goode Solar Telescope has been enabling us to advance solar MCAO from early conceptual demonstrations to science grade wide-field image correction. We report on recent improvements to the control loop and we comment on issues such as the co-aligning of wavefront sensors and deformable mirrors and the sensitivity of wavefront sensor gains. Further, we comment on the challenges to wavefront sensing and the control system architecture faced when scaling up to a 4-meter aperture. Finally, we present an early concept of the future MCAO upgrade for the Daniel K. Inouye Solar Telescope.

We are building a next-generation laser adaptive optics system, Robo-AO-2, for the UH 2.2-m telescope that will deliver robotic, diffraction-limited observations at visible and near-infrared wavelengths in unprecedented numbers. The superior Maunakea observing site, expanded spectral range and rapid response to high-priority events represent a significant advance over the prototype. Robo-AO-2 will include a new reconfigurable natural guide star sensor for exquisite wavefront correction on bright targets and the demonstration of potentially transformative hybrid AO techniques that promise to extend the faintness limit on current and future exoplanet adaptive optics systems.

We present a new testing facility hosted at the Coude focus of the INAF-Padova Copernico Telescope, a project carried on within the ADaptive Optics National Italian laboratories - ADONI. A permanent laboratory for on-sky experimentation accessible to the AO community, with the aim of hosting visiting multi-purpose instrumentation that may be directly tested on sky. We will give an overview of the activities carried on, describing the refurbishment activities at the hosting structure that allowed the opening of the facility: the implementation of the opto-mechanical train down to the Coude focus, and the creation of the laboratory. This facility provides a powerful scientific and technical test bench for new instrumental concepts, which may eventually be incorporated later in the next generation ELTs telescopes.

New space missions dedicated to exoplanet imaging will rely on coronagraphs to address the high contrast between the stars and their environments. In order to avoid the image of planets to be lost in post-coronagraphic starlight residuals, high precision wavefront sensing and control is a key element to these missions. We present recent results of simultaneous post-coronagraphic phase and amplitude sensing obtained on the THD bench using the coronagraphic phase diversity. We also present results of simulation studies on the non-linear dark hole technique to assess the main limitations of this technique. Finally, we present a first experimental validation of its principle and corroborate expectations on its speed of convergence. These results suggest that the non-linear dark hole is a good candidate for wave-front control for future space-based exoplanet imaging missions, where fast techniques to produce deep dark holes are of paramount importance.

The low wind effect is a phenomenon disturbing the phase of the wavefront in the pupil of a large telescope obstructed by spiders, in the absence of wind. It can be explained by the radiative cooling of the spiders, creating air temperature inhomogeneities across the pupil. Because it is unseen by traditional adaptive optics (AO) systems, thus uncorrected, it significantly degrades the quality of AO-corrected images. We provide a statistical analysis of the strength of this effect as seen by VLT/SPHERE after 4 years of operations. We analyse its dependence upon the wind and temperature conditions. We describe the mitigation strategy implemented in 2017: a specific coating with low thermal emissivity in the mid-infrared was applied on the spiders of Unit Telescope 3. We quantify the improvement in terms of image quality, contrast and wave front error using both focal plane images and measured phase maps.

For Extremely Large Telescope (ELT) adaptive optics (AO) systems, multiple Sodium Laser Guide Star (LGS) wavefront sensors (WFSs) are required to achieve high sky coverage and diffraction limited performance. However, temporal and spatial variation of the sodium profile causes measurement biases that appear at all time scales and vary between LGS WFSs. To make things worse, optical design residuals, polishing and alignment errors also create non-common-path aberrations (NCPA) that vary between sub-apertures and different WFS, causing LGS WFS to work significantly off null with a nonlinear response. The induced aberrations are consequently non-radially symmetric, even for center launch laser beams with polar coordinate detectors. Natural guide star (NGS) based truth wavefront sensors are often suggested as a method of sensing these LGS WFS aberrations, but a single sensor will suffer strong anisoplanatism that may introduce additional errors. In this paper, we present mitigation strategies and performance estimations based on simulations for the Thirty Meter Telescope (TMT) Narrow Field Infrared AO system (NFIRAOS).

In an adaptive optics (AO) system, finite time delays contribute a relatively large amount to the overall wavefront error. The temporal error, due to the time delays, adds to the speckle halo which is visible in the science plane of a high contrast imaging (HCI) instrument. The halo limits the inner working angle, preventing HCI from probing regions where we expect Earth-like planets. Our research focuses on understanding the non-stationary behavior of atmospheric turbulence and its effects on the temporal error and the contrast. The wind vector greatly influences the turbulence-induced wavefront phase error. In the framework of the von Karman power spectral density (PSD) of wavefront phase, the wind speed changes the cut-off frequency as well as the gain of the spectrum. We aim to understand the behavior of the wind vector on sub-second timescales using data from the Thirty Meter Telescope site testing campaign at Mauna Kea. The nocturnal measurements we study are from 287 nights throughout the years of 2006-2008, taken at a height of 7 m with a maximum sampling rate of 60 Hz. We first compare the observational PSD to the Kaimal PSD. We then present an expression for the observational PSD, a fit to a more general PSD similar to the Kaimal PSD, to describe the wind speed located at Area E (northern plateau) on Mauna Kea. Using the fitted PSD, we construct a fractionally integrated ARMA model that can be used to create an artificial wind speed time series to be fed into phase screen simulations to generate realistic wind-varying phase screens. We examine how the contrast, achieved by the AO system, varies with the wind fluctuations.

The ESO’s adaptive optics facility (AOF) is ending its commissioning at Paranal (Chile). It feeds two second-generation instruments of the VLT-UT4 telescope, HAWK-I and MUSE, with turbulence corrected wavefronts through the GALACSI and GRAAL modules. The main features of the AOF are its deformable secondary mirror with 1170 actuators and a laser asterism of 4 artificial stars that probe the atmosphere via four high-resolution Shack-Hartmann wavefront sensors (WFS), each with 40x40 subapertures. The system provides ground layer adaptive optics (GLAO) and laser tomography adaptive optics (LTAO) capabilities. In order to support the commissioning phases of the project, and later optimize and diagnose the operation of the system, a turbulence profiler has been developed and installed in SPARTA, the AOF real time controller (RTC). The profiler estimates two key turbulence parameters: the C_n ²(h) and the outer scale (L₀(h)) profiles and no limit on the number of the estimated layers exists, but for eight layers, the method takes about 2 minutes to yield a full characterization of the atmosphere. The maximum line of sight distance that the profiler can probed the atmosphere depends on the star separation defined for each operation mode: 3km for GRAAL; 14 km for GALACSI wide field and over 35km for GALACS narrow field mode. The remaining turbulence above these maxima (unseen turbulence from the undetected layers) are essential in the GRAAL mode and it is reliably estimated thanks to a novel method to determine the noise in the WFSs, which is mandatory for estimating this upper segment of the turbulence. The technique is also useful to alert about operational problems such as dome seeing and mis-registrations. The method is currently installed in the SPARTA RTC, providing continuous online estimations for the GALACSI (narrow and wide field modes), and for GRAAL mode. Results for several nights comprising hundreds of profiles show very good agreement with other independent measurements.

The optical turbulence profile is a key parameter in tomographic reconstruction. With interest in tomographic adaptive optics for the next generation of ELTs, turbulence profiling campaigns have produced large quantities of data for observing sites around the world. In order to be useful for Monte Carlo AO simulation, these large datasets must be reduced to a small number of profiles. There is commonly large variation in the structure of the turbulence, therefore statistics such as the median and interquartile range of each altitude bin become less representative as features in the profile are averaged out. Here we present the results of the use of a hierarchical clustering method to reduce the 2018A Stereo-SCIDAR dataset from ESO Paranal, consisting of over 10,000 turbulence profiles measured over 83 nights, to a small set of 18 that represent the most commonly observed profiles.

Scientific exploitation in ground-based astronomy is improved thanks to adaptive optics (AO) that restore diffraction-limit angular resolution. Besides, the ultimate data interpretation is delivered by post-processing techniques that usually relies on a Point spread function (PSF) model. Nevertheless, existing methods to constrain this model based on standard pipeline encounter the spatial and time variations of the AO PSF. In order to improve accuracy on key science observables, such as photometry and astrometry, alternative methods are investigated, such as PSF reconstruction (PSF-R), designed to estimate the PSF from AO control-loop data and key atmosphere and system parameters. We aim in this paper at retrieving directly these relevant inputs we need to reconstruct the PSF using an hybrid approach, that couples AO telemetry with focal plane images, named as Focal plane profiling and reconstruction (FPPR). It adjusts atmosphere parameters (the C²_n (h) profile) and optical gains in the system. We describe the FPPR method that is applied to on-sky Keck images in engineering mode operated with either natural or laser guide star and show we get 1% of accuracy on respectively the Strehl-ratio and the PSF FWHM reconstruction.

Stack Array Mirrors (SAM) technology offers high order correction, with up to several thousands of actuators, controllable at high frequency, up to several kHz. A new generation of piezo-electric actuators with high reliability has been developed during the last years. This technology is well-adapted for large deformable mirrors (DMs) with thousands of actuators for future needs for Extremely Large Telescopes. We present the design and the modelling of the two large DMs for NFIRAOS, the multi-conjugate adaptive optics system of the Thirty Meter Telescope (TMT): DM0 which shows 3125 actuators and DM11 which shows 4548 actuators. A DM prototype with 616 actuators has been manufactured to validate the manufacturing steps and the specifications of the future large DMs, including their behavior at both ambient and low temperature (-30°C). The prototype includes the new generation of piezo actuators with improved reliability thanks to an optimization of the fabrication processes. Experimental results of accelerated ageing tests and mechanical fatigue are presented. After complete assembly, the prototype is qualified in a specific cool chamber with interferometric measurements. The results are the following: operational stroke higher than 10 μm PV at both ambient and -30°C with uniformity better than 5%, overall non-linearity lower than 5%, resonance frequency of the actuators higher than 10 kHz. Based on the measurements done on the overall temperature range (+20°C to -30°C), the best flat is lower than the goal specification of 10 nm RMS mechanical. An enhanced protected silver coating done by magnetron sputtering allows a high level of reflectivity especially in the near infrared range and long-life durability.

As the deep field surveys strategy represents a well popular way to study the cosmology and the formation and evolution of galaxies, we investigated how the new generation of extremely large telescopes (ELTs) will perform in this field of research. Our simulations, which combine a number of technical, tomographic and astrophysical information, take advantages of the Global-MCAO approach, a well demonstrated method that can be applied in absence of laser guide stars because it exploits only natural references. A statistics of the expected performance in a sub-sample of 22 well-known surveys are presented here.

There are long existing limitations of the sky coverage of astronomical Adaptive Optics (AO) systems that use natural guide stars (NGSs) as reference sources. In this work, we present numerical simulations and lab test results of an optical NGS pyramid wavefront sensor (PWFS) for the MMT AO system. The potential increase of sky coverage benefits from the gain in sensitivity of the PWFS in a closed-loop NIR AO system compared with the optical Shack-Hartmann wavefront sensor (SHWFS). The upgraded MMT AO WFS system will use IR avalanche photodiode (APD) array with extremely low readout noise (at sub-electron level), run at a high frame rate (over 1kHz), and cover the wavelength range from 0.85-1.8 μm. This upgraded system will access a larger portion of the sky by looking at fainter, redder reference stars. We use ”yao” simulation to show the expected limiting magnitude gain of NIR PWFS compared with the existing optical SHWFS. The sky coverage will increase by 11 times at the Galactic plane and by 6 times at the North Galactic Pole when compared to traditional optical WFSs. This novel WFS will also enable observations of the dust obscured plane of the Galaxy, where the optical light of most stars is more extincted. We demonstrate the basic lab test with a set of double roof prisms. We evaluate the overall performance of the PWFS on our lab AO bench, present captured micro-pupil images and do wavefront reconstruction. We will upgrade to SAPHIRA and pyramid prism for later lab test. We plan to implement this system at MMT and carry out on-sky tests in Spring 2019.

While radial velocity and transit techniques are efficient to probe exoplanets with short orbits, the study of long-orbit planets requires direct imaging and coronagraphic techniques. However, the coronagraph must deal with planets that are 10⁴ to 10¹⁰ fainter than their hosting star at a fraction of arcsecond, requiring efficient coronagraphs at short angular separation. Phase masks proved to be a good solution in monochromatic or limited spectral bandwidth but expansion to broadband requires complex phase achromatization. Solutions use photonic crystals, subwavelength grating or liquid crystal polymers but their manufacturing remains complex. An easier solution is to use photolithography and reactive ion etching and to optimize the azimuthal phase distribution like achieved in the six-level phase mask (SLPM) coronagraph (Hou et al. 2014). We present here the laboratory results of two SLPM coronagraphs enabling high-contrast imaging in wide-band. The SLPM is split in six sectors with three different depths producing three levels of optical path difference and yielding to uniform phase shifts of 0, π or 2π at the specified wavelength. Using six sectors instead of four sectors enables to mitigate the chromatic effects of the SLPM compared to the FQPM (Four-Quadrant Phase Mask) while keeping the manufacturing easy. Following theoretical developments achieved by University of Shanghai and based on our previous experience to fabricate FQPM components, we have manufactured SLPM components by reactive ion etching at Paris Observatory and we have tested it onto the THD2 facility at LESIA. The THD2 bench was built to study and compare high-contrast imaging techniques in the context of exoplanet imaging. The bench allows reducing the starlight below a 10⁻⁸ contrast level in visible/near-infrared. In this paper, we show that the SLPM is easy to fabricate at low cost and is easy to implement with a unique focal plane mask and no need of pupil apodization. Detection of a planet can be achieved at small inner working angle down to 1 λ/D. The on-axis attenuation of the best SLPM component reaches 2 × 10⁻⁵ at λ = 800 nm and is better than 10⁻⁴ in intensity over a 10% spectral bandwidth. Along the diagonal transition, we show that the off-axis transmission is attenuated by less than 3% over a 10% bandwidth and will need to be calibrated. Any etching imperfections can affect the SLPM performance, by lowering the on-axis attenuation and by changing the optimal wavelength. Despite few nanometers of uncertainty for etching the depths, we show that this first component can provide a high-contrast attenuation in laboratory

The Epsilon Eridani system is a star system ~10 ly away predicted to be similar to our solar system, making it a particularly interesting target for exoplanet detection. A Jupiter-like exoplanet has been predicted at 1.88 arcsec using radial velocity techniques, and an outer debris disk has been imaged at 35 - 90 AU with Spitzer and CSO observations. We present a preliminary survey of the inner system using the MagAO instrument with the Magellan Clay telescope in Chile. We apply and evaluate the Karhunen-Loeve Image Projection technique, which estimates the point spread function (PSF) of the central star for high-contrast imaging using Principal Component Analysis (PCA). We perform this analysis by adapting the pyKLIP package, which was developed for analyzing data from the Gemini Planet Imager instrument, to be used with data from the MagAO/VisAO instrument.

The success of ground-based, high contrast imaging for the detection of exoplanets in part depends on the ability to differentiate between quasi-static speckles caused by aberrations not corrected by adaptive optics (AO) systems, known as non-common path aberrations (NCPAs), and the planet intensity signal. Frazin (ApJ, 2013) introduced a post-processing algorithm demonstrating that simultaneous millisecond exposures in the science camera and wavefront sensor (WFS) can be used with a statistical inference procedure to determine both the series expanded NCPA coefficients and the planetary signal. We demonstrate, via simulation, that using this algorithm in a closed-loop AO system, real-time estimation and correction of the quasi-static NCPA is possible without separate deformable mirror (DM) probes. Thus the use of this technique allows for the removal of the quasi-static speckles that can be mistaken for planetary signals without the need for new optical hardware, improving the efficiency of ground-based exoplanet detection. In our simulations, we explore the behavior of the Frazin Algorithm (FA) and the dependence of its convergence to an accurate estimate on factors such as Strehl ratio, NCPA strength, and number of algorithm search basis functions. We then apply this knowledge to simulate running the algorithm in real-time in a nearly ideal setting. We then discuss adaptations that can be made to the algorithm to improve its real-time performance, and show their efficacy in simulation. A final simulation tests the technique’s resilience against imperfect knowledge of the AO residual phase, motivating an analysis of the feasibility of using this technique in a real closed-loop Extreme AO system such as SCExAO or MagAO-X, in terms of computational complexity and the accuracy of the estimated quasi-static NCPA correction.

The studies were carried out preliminary within the framework of the RSF project 15-19-20013 "Creation of an adaptive system ensuring operation of a large-sized solar telescope under conditions of strong atmospheric turbulence." It is known that the use of adaptive optics (AO) systems is the most radical way for reducing the effect of atmospheric distortions. AO systems correct distortions introduced by the Earth's atmosphere into the image of a space object in real time. The creation of an AO system for large-aperture solar telescopes still is a scientific and engineering challenge. Currently, for the largest Russian solar telescopes, in particular, the Large Solar Vacuum Telescope (LSVT), the Automated Solar Telescope (AST) and the 3-meter Large Solar Telescope (LST) under development, promising new- generation systems are being developed and implemented based on the principles of multi-mirror adaptive correction.

One of the main pursuits of the MagAO-X project is imaging planets around nearby stars with the direct detection method utilizing an extreme AO system and a coronagraph and a large telescope. The MagAO-X astronomical coronagraph will be implemented on the 6.5 meter Clay Magellan Telescope in Chile. The 22 mirrors in the system require a high level of mirror stability. Our goal is less than 1 microradian drift in tilt per mirror per one degree Celsius change in temperature. There are no commercial 2inch kinematic optical mounts that are truly “zero-drift” from 0-20C. Our solution to this problem was to develop a locking clamp to keep our optics stable and fulfill our specifications. After performing temperature variation and thermal shock testing, we conclude that this novel locking clamp significantly increases the thermal stability of stainless steel mounts by ~10x but still allows accurate microradian positioning of a mirror. A provisional patent (#62/632,544) has been obtained for this mount.

The search for new exoplanets by direct imaging is a very active research topic in astronomy. The detection is particularly challenging because of the very high contrast between the host star and the companions. They thus remain hidden by a nonstationary background displaying strong spatial correlations. We propose a new algorithm named PACO (for PAtch COvariances) for reduction of differential imaging datasets. Contrary to existing approaches, we model the background correlations using a local Gaussian distribution that locally captures the spatial correlations at the scale of a patch of a few tens of pixels. The decision in favor of the presence or the absence of an exoplanet in then performed by a binary hypothesis test. The method is completely parameter-free and produces both stationary and statistically grounded detection maps so that the false alarm rate, the probability of detection and the contrast can be directly assessed without post-processing and/or Monte-Carlo simulations. We describe in a forthcoming paper its detailed principle and implementation. In this paper, we recall the principle of the PACO algorithm and we give new illustrations of its benefits in terms of detection capabilities on datasets from the VLT/SPHERE-IRDIS instrument. We also apply our algorithm on multi-spectral datasets from the VLT/SPHERE-IFS spectrograph. The performance of PACO is compared to state-of-the-art algorithms such as TLOCI and KLIP-PCA.

Despite promising astrometric signals, to date there has been no success in direct imaging of a hypothesized third member of the Sirius system. Using the Clio instrument and MagAO adaptive optics system on the Magellan Clay 6.5 m telescope, we have obtained extensive imagery of Sirius through a vector apodizing phase plate (vAPP) coronagraph in a narrowband filter at 3.9 microns. The vAPP coronagraph and MagAO allow us to be sensitive to planets much less massive than the limits set by previous non-detections. However, analysis of these data presents challenges due to the target’s brightness and unique characteristics of the instrument. We present a comparison of dimensionality reduction techniques to construct background illumination maps for the whole detector using the areas of the detector that are not dominated by starlight. Additionally, we describe a procedure for sub-pixel alignment of vAPP data using a physical-optics-based model of the coronagraphic PSF.

We present the R and D status of the Speckle-Free Angular Differential Imaging method (SFADI), that we developed for the SHARK-VIS high-contrast imager for the LBT telescope. The technique bases on the acquisition of kHz frame-rate image sequences, which we combine in post-processing after speckle identification and suppression in each frame. With respect to the standard angular differential imaging, this method reaches a much smoother residual background and hence higher detection contrast at a given signal-to-noise ratio. Furthermore, it can reveal faint extended sources around bright central stars, and can use de-rotated images as well as quick second-lasting sequences. We reached a contrast of around 10^-5 for integration times of the order of tens of minutes at 100 mas for a 5.7th magnitude star, as we demonstrated on both a real-sky acquisition and at the SHARK-VIS laboratory test bench. Such long sequences though produces a large amount of data (around a million frames every 15 minutes) that we manage to processed in a reasonable computation time with the described implementation scheme.

Recurrence Quantification Analysis (RQA) is a non-linear time series analysis technique widely employed in many different research fields. Among the many applications of this method, it has been shown that it can be successfully employed in the detection of small signals embedded into noise. In this work we explore the possibility of using the RQA in astronomical high contrast imaging, for the detection of faint objects nearby bright sources in very high frame rate (1 KHz) data series. For this purpose, we used a real 1 kHz image sequence of a bright star, acquired with the SHARK-VIS forerunner at LBT. Our results show excellent performances in terms of detection contrasts even with a very short data sequence (a few seconds). The use of RQA in astronomical high contrast imaging is discussed in light of the possible science applications and with respect to other techniques like, for example, the angular differential imaging (ADI) or the Speckle-Free ADI (SFADI).

The predominant effect of the atmosphere on the incoming wavefront of an astronomical object is the introduction of phase distortion, resulting in an aberrated image from ground-based telescopes. Since wavefront perturbations cannot be directly measured from an image, a wavefront sensor can use intensity variations from a point source to measure specific wavefront aberrations. However, processing of measured aberration data from these sensors can be computationally intensive and this is a challenge for real-time image restoration. To accurately represent such wavefront aberrations with improved processing time, we analyse how the ridgelet transform can be used with the slope-based wavefront sensor i.e., geometric wavefront sensor, in an open-loop configuration. Ridgelet analysis is performed in the Radon domain, where each Radon line integral is computed over N angles, and is represented by a wavelet. Contrasting the behaviour of the ridgelet transform to generate Zernike polynomials with the geometric wavefront sensor, which uses the properties of geometric optics, is the main aim of this paper. We first decompose the image into a Radon domain, and then analyse each line integeral of a Radon transform by a wavelet transform. We show that multi-resolution geometric analysis with ridgelets results in lower wavefront errors, particularly for low photon counts, and computational efficiency of the geometric wavefront sensor is improved by almost a factor of 2.

The angular differential imaging (ADI) is used to improve contrast in high resolution astronomical imaging. An example is the direct imaging of exoplanet in camera fed by Extreme Adaptive Optics. The subtraction of the main dazzling object to observe the faint companion was improved using Principal Component Analysis (PCA). It factorizes the positive astronomical frames into positive and negative components. On the contrary, the Nonnegative Matrix Factorization (NMF) uses only positive components, mimicking the actual composition of the long exposure images.

We aim at improving solar images partially compensated by Adaptive Optics (AO) or Ground-Layer (GL) AO using a phase diversity (PD) method. To reduce computational time in the PD execution, we develop a computer cluster system that enables restoration of several images in parallel. We set a PD-observational system downstream of an AO system in the Hida Observatory in Japan. Driving the AO system, we recorded focused and defocused solar images. They were segmented to partial images, and then were restored by the PD method. We show the results of solar image restoration, and also demonstrate the reduction of processing time by the computer cluster.

We report on the design and initial laboratory testing of the Adaptive Optics Imaging (AOI) system. AOI has been developed by the Research School of Astronomy and Astrophysics (RSAA) at the Australian National University (ANU), in partnership with the Space Environment Research Centre (SERC), for imaging satellites and debris in low Earth orbit (LEO) and geostationary orbit (GEO). From AO corrected images we will resolve features greater than 50 cm allowing size, shape and orientation characterisation.

A future upgrade of the Keck II telescope’s adaptive optics system will include a near-infrared pyramid wavefront sensor. It will benefit from low-noise infrared detector technology, specifically the avalanche photodiode array SAPHIRA (Leonardo). The system will either operate with a natural guide star in a single conjugated adaptive optics system, or using a laser guide star (LGS), with the pyramid working as a low-order sensor. We present a study of the pyramid sensor’s performance via end-to-end simulations, including an analysis of calibration strategies. For LGS operation, we compare the pyramid to LIFT, a focal-plane sensor dedicated to low-order sensing.

We report experiments of solar ground-layer (GL) adaptive optics (AO) using the 60cm domeless solar telescope of the Hida Observatory, Japan. We developed an averaging-type GL wavefront sensor and confirmed that it properly worked in computer simulations. We set the wavefront sensor behind a conventional AO system and modified AO software so as to drive a deformable mirror using the GL sensor. We conducted solar observations with the GLAO system in September, 2017. It worked to improve observational images over wide fields.

The AO188 Single Conjugate facility AO system at Subaru Telescope delivers diffraction-limited images in near-IR in natural and laser guide star modes. We have recently started a major upgrade of AO188 to fulfill the high performance requirements of its downstream instruments, including the Subaru Coronagraphic Extreme-AO. The first phase of this upgrade started in 2017 with the integration of a new real time computer (RTC) and real time system (RTS) CACAO(https://github.com/CACAO-org/CACAO), an open-source real-time software for adaptive optics developed collaboratively and used extensively by the SCExAO instrument. This major upgrade will enable loop optimization, predictive control and include diagnosis tools, therefore improving the performance and stability of AO188 and its downstream instrument module. This paper introduces the architecture of the new RTS describing the different steps we followed to adapt CACAO to our AO interfaces and aging hardware, in preparation of our first engineering tests on-sky achieved successfully on July 23rd 2018.

SALTO is a Belgian project aiming to build a complete 1 m telescope demonstrator including a single-conjugated adaptive optics (AO) system together with a Rayleigh laser guide star system. The underlying objective of SALTO consists in developing the Belgian expertise regarding AO systems for medium size telescopes (i.e. diameter from 1 to 4m), for application in astronomy, optical communication or detection of low-Earth orbit objects. The project approach is to base the design on COTS components, in order to reduce complexity, and to favor both robustness and automation of the system over performance. The SALTO demonstrator will be located at Redu Space Services in the Belgian countryside. Therefore the major challenge of the project will be to deal with poor seeing, far worst than astronomical standards, while preserving robust and reasonable correction in the red-visible and near-infrared wavelength range. Here, we present our system baseline, the expected performance, and the preliminary design of the AO system. We conclude with the current prospects for the project.

A new real-time control system will be implemented within the Keck II adaptive optics system to support the new near-infrared pyramid wavefront sensor. The new real-time computer has to interface with an existing, very productive adaptive optics system. We discuss our solution to install it in an operational environment without impacting science. This solution is based on an independent SCExAO-based pyramid wavefront sensor realtime processor solution using the hardware interfaces provided by the existing Keck II real-time controller. We introduce the new pyramid real-time controller system design, its expected performance, and the modification of the operational real-time controller to support the pyramid system including interfacing with the existing deformable and tip-tilt mirrors. We describe the integration of the Saphira detector-based camera and the Boston Micromachines kilo-DM in this new architecture. We explain the software architecture and philosophy, the shared memory concept and how the real-time computer uses the power of GPUs for adaptive optics control. We discuss the strengths and weaknesses of this architecture and how it can benefit other projects. The motion control of the devices deployed on the Keck II adaptive optics bench to support the alignment of the light on the sensors is also described. The interfaces, developed to deal with the rest of the Keck telescope systems in the observatory distributed system, are reviewed. Based on this experience, we present which design ideas could have helped us integrate the new system with the previous one and the resultant performance gains.

We present improvements to the telescope and the Adaptive Optics (AO) upgrades that will be installed in 2018 to the 1.5m GREGOR solar telescope. An exchange of the telescope’s secondary mirror has improved the contrast in the AO wavefront sensor (WFS). The repair of the telescope building’s faulty facade plates will result in better dome/building seeing. The daytime (solar) wavefront sensor camera will be replaced by a high full well capacity model, enabling the AO to lock on granulation and faculae close to the solar limb during bad seeing conditions. A 2x2 guide region ground layer AO (GLAO) mode will provide a 10” FoV with a much flatter PSF as compared to conventional AO. A change of the night-time wavefront sensor camera will result in a larger WFS FoV, improving the AO tracking of the large solar system planets like Jupiter and Saturn. A new AO mode of operation will allow the tracking of of solar prominences using a narrow-band H-alpha filter.

Coupling a high-contrast imaging instrument to a high-resolution spectrograph has the potential to enable the most detailed characterization of exoplanet atmospheres, including spin measurements and Doppler mapping. The high-contrast imaging system serves as a spatial filter to separate the light from the star and the planet while the high-resolution spectrograph acts as a spectral filter, which differentiates between features in the stellar and planetary spectra. The Keck Planet Imager and Characterizer (KPIC) located downstream from the current W. M. Keck II adaptive optics (AO) system will contain a fiber injection unit (FIU) combining a high-contrast imaging system and a fiber feed to Keck’s high resolution infrared spectrograph NIRSPEC. Resolved thermal emission from known young giant exoplanets will be injected into a single-mode fiber linked to NIRSPEC, thereby allowing the spectral characterization of their atmospheres. Moreover, the resolution of NIRSPEC (R = 37,500 after upgrade) is high enough to enable spin measurements and Doppler imaging of atmospheric weather phenomenon. The module was integrated at Caltech and shipped to Hawaii at the beginning of 2018 and is currently undergoing characterization. Its transfer to Keck is planned in September and first on-sky tests sometime in December

Adaptive Optics (AO) is an innovative technique that substantially improves the optical performance of groundbased telescopes. The SOAR Adaptive Module (SAM) is a laser-assisted AO instrument, designed to compensate ground-layer atmospheric turbulence in near-IR and visible wavelengths over a large Field of View. Here we detail our proposal to upgrade SAM, dubbed SAMplus, that is focused on enhancing its performance in visible wavelengths and increasing the instrument reliability. As an illustration, for a seeing of 0.62 arcsec at 500 nm and a typical turbulence profile, current SAM improves the PSF FWHM to 0.40 arcsec, and with the upgrade we expect to deliver images with a FWHM of ≈ 0.34 arcsec - up to 0.23 arcsec FWHM PSF under good seeing conditions. Such capabilities will be fully integrated with the latest SAM instruments, putting SOAR in an unique position as observatory facility.

The Natural Guide Star Adaptive Optics system for the Gran Telescopio Canarias (GTC) is in its integration phase, and meanwhile the Laser Guide Star update, which will follow two years later, has recently passed its Preliminary Design Phase. This LGS Facility will feature a TOPTICA Na laser, and it will open up the scientific possibilities of GTC enlarging the sky coverage of the AO system and allowing to study at high resolution more scientific targets. A trade-off study was undertaken to decide, among other details, the launching position of the laser and the feasibility of a further upgrade to an MCAO system vs technical complexity, cost and maintenance. As part of this study we have analysed the performance of the GTCAO LGS system to ensure that it will fulfil the specifications in all the different scenarios. Complete end-to-end (E2E) simulations have been performed using the versatile Durham AO Simulation Platform (DASP), including not only real atmospheric profiles from Observatorio del Roque de los Muchachos but also the measured windshake spectrum of the secondary mirror of GTC, the different control loops (TT, DM, focus), the laser uplink jitter and launching telescope divergence, the segmented primary mirror and it's cophasing residual errors, the rotating pupil etc... In this contribution we present a detailed error budget of the system and the results of the E2E simulations that show the impact that such a system will have on the science done with GTC.

Over the past few years, several large ground-based facilities have enhanced their exoplanet direct imaging capabilities to observe planetary companions and debris disks around nearby stars. The Gran Telescopio Canarias (GTC) will soon have its first high-contrast capabilities with FRIDA. This near-infrared imager and integral field spectrograph will operate with GTCAO, the adaptive optics system of the telescope, to cover a broad range of astrophysical topics. In 2008, we performed preliminary studies to design a high-contrast mode for FRIDA. In this communication, we revisit these studies by investigating different options in coronagraphy to define a final high-contrast baseline for this instrument. Acknowledging the mechanical constraints of FRIDA and the GTCAO performance for high-contrast observations (60% Strehl ratio in K-band), we evaluate different options such as standalone pupil apodizations and classical Lyot coronagraphs to achieve a 10⁻⁵ contrast at 200-300 mas from an observed star over wide spectral bands. We then derive the adopted solutions for design and manufacturing of the prototypes. Finally, we discuss possible combinations of high-dispersion spectroscopy and high-contrast imaging for advanced exoplanet observations with this instrument.

The Gran Telescopio Canarias Adaptive Optics (GTCAO) is a single-conjugated post-focal system with a Shack Hartmann wavefront sensor, and one Deformable Mirror (DM) conjugated to the pupil. The optical design for tip-tilt correction includes two different mirrors, DM and the telescope M2, being M2 also used for off-loading the DM to avoid reaching its stroke limits. This optical configuration is open to different control strategies that have been simulated with Matlab. Later it has also been simulated using Durham Adaptive optics Real-time Controller (DARC) and its AO simulator, DASP. Finally some preliminary laboratory results are presented.

A near-infrared, high order pyramid wavefront sensor will be implemented on the Keck telescope, with the aim of providing high resolution adaptive optics correction for the study of exoplanets around M-type stars and planet formation in obscured star forming regions. The pyramid wavefront sensor is designed to support adaptive optics correction of the light to an imaging vortex coronagraph and to a fiber injection unit that will feed a spectrograph. We present the opto-mechanical design of the near-infrared pyramid wavefront sensor, the optical performance, and the alignment strategy. The challenges of designing the assembly, as well as a fiber injection unit, to fit into the limited available space on the Keck adaptive optics bench, will also be discussed.

The Adaptive Optics module and the Calibration Unit of the Enhanced Resolution Imager and Spectrograph (ERIS) share a similar Instrument Control Electronics (ICE). The architecture was designed according to the ESO standards and specifications. The large number of functions of these two complex subsystems are ensured by the automation software running on a Beckhoff PLC based control system. This paper describes the AO and CU design, their Instrument Control Electronics, main functions of the two subsystems and the activities performed during the first period of the MAIV phase.

The LOR WFS module will provide low and medium order sensing for the MAORY MCAO mode. It is composed of three identical units, hosting two Shack-Hartmann wavefront sensors each: an infrared 2×2 sub-apertures, used for low order modes, and a visible 10×10 sub-apertures for the slow truth sensing needed to correct the LGS WFS measurements. In this paper we show the current design of the NGS WFS control electronics and the interfaces with the MICADO instrument.

The application of phase diversity is first invested in simulation to characterize ideal parameters to GPI with faithfully simulated calibration source data. The best working simulation parameters are applied to real GPI data and shown to recover an injected astigmatism. The estimated GPI NCPA are then corrected and the Strehl ratio is improve by ⇠ 5%, although the application is rudimentary and a more thorough correction will be applied in the near future.

Sodium guide star technologies for Adaptive Optics (AO) have been around for over 20 years. During this time, the technologies for the lasers used to excite the mesospheric sodium have been in constant development, with the goals being not only to excite as much sodium as possible, but to do so efficiently, while producing a round guide star, and while offering a reliable facility. The first lasers in use were dye lasers with a liquid gain medium, while these lasers were able to produce sodium guide stars, the liquid dye used was toxic and flammable. The second generation of guide star lasers used sum-frequency-mixed solid-state lasers. These lasers provided excellent return but were notoriously difficult to calibrate and maintain, requiring a full-time laser engineer on staff. The current third generation of sodium guide star lasers use Raman fiber amplification to generate a laser that is very efficient at exciting sodium with a good spot profile and offer a high degree of reliability. The Gemini South observatory for the last few years has been in the process of obtaining one of these third-generation lasers, a Toptica Sodium Star 20/2 while maintaining its second-generation Lockheed Martin Coherent Technologies (LMCT) 50W CW Mode-locked laser. In October of 2017 successful on-sky commissioning of the Toptica laser was executed while the LMCT laser was still active and in operations. During the course of the commissioning run both lasers were used on sky in close in time in possible. We present a comparative study of the performance of each laser.

We report the current status of the laser guide star upgrade at Subaru Telescope with a new, more powerful TOPTICA/MPBC laser. While we recycle many of our existing components, such as laser launch telescope, we need to design a new mirror-based laser relay system to replace the current fiber-based relay to accommodate the high power beam. The laser unit has been delivered to Subaru office in March 2018 and installed in a testing lab in June 2018. We describe the preliminary design and its requirements and report future plans. This upgrade will not only improve our current adaptive optics system but also be the first step toward the future laser tomography and ground layer adaptive optics system at Subaru Telescope.

The return flux from a sodium laser guide star suffers, at large angles between the geomagnetic field and the laser beam, from the reduction in optical pumping due to spin-precession of sodium atoms. This detrimental effect can be mitigated by modulating the circular polarization of a continuous-wave laser beam in resonance with the Larmor frequency of sodium atoms in the mesosphere. We present an investigation based on numerical modeling to evaluate the brightness enhancement of a laser guide star with polarization modulation of a continuous-wave laser beam at different observatories.

For many years now most major astronomical observatories have been using adaptive optics (AO) with the aid of optical or ultra-violet lasers to generate artificial guide stars. While the majority of laser-based AO systems in use have been used to feed infrared science cameras, there have always been scientific reasons to use these systems with optical cameras as well. One challenge in the optical region is that these lasers themselves contaminate the sky at their respective wavelengths. This contamination is an issue not only for the telescope itself but also for any other optical telescope looking at or near the laser beam. Up until recently it was thought that these lasers only contaminated the sky at their respective wavelengths. However, recent studies at the VLT have shown that there are additional, albeit much weaker, sources of contamination caused by inelastic Raman scattering of the laser light, also in the optical region. These observations were made with the VLTs MUSE spectrograph looking at the ESO 4LGSF which uses 4 Toptica Sodium Star 20/2 lasers to make a variety of different laser guide star constellations both on axis and off axis from the science camera, the total output power of the 4 lasers is on the order of 88W. At the Gemini South observatory at Cerro Pachón we propagated either a single 45W Lockheed Martin Coherent Technologies (LMCT) pulsed laser, or a single Toptica Sodium Star 20/2 continuous wave laser. In each case the beam was split into 5 beams of equal intensity and center-launched so as to always be on axis with the science camera. We used the GMOS-S spectrograph to take on axis spectra of the laser beams, looking for the same Raman lines detected at the VLT. For both lasers, we were able to detect the Raman emission lines. In this paper we will present the results from our GMOS-S spectroscopy detailing the wavelength and intensities of the Raman emission for each laser.

A motorized laser Beam Injector Module (BIM) has been designed to integrate the new Toptica SodiumStar 20/2 laser to the Beam Transfer Optics (BTO) subsystem of the Gemini South telescope. The main goal is to inject the new laser beam co-axially to the BTO optical axis without altering the optical path of the current Lockheed Martin Coherent Technologies (LMCT) sodium laser. The optical design consists of a custom high-power attenuator offering two power modes, an opto-mechanical laser switch to commute between the two laser guide star facilities within a short period of time and a set of tip-tilt picomotor mirror mounts for BTO optical alignment. The motorized module is remotely controlled via an EPICS command interface by the laser operator that can propagate both lasers consecutively on sky for the measurement of the sodium layer guide star photon return. The laser beam factor quality and optical characteristics of the beam injector output beam have been measured within the Gemini South Laser Guide Star (GS-LGS) requirements. This paper presents a general overview of the new sodium laser facility and the beam injector optomechanical design. It reports on the optical calibration, laser beam characterization, telescope integration and BTO optical alignment.

NFIRAOS (Narrow-Field InfraRed Adaptive Optics System) will be the first-light multi-conjugate adaptive optics system for the Thirty Meter Telescope (TMT). NFIRAOS houses all of its opto-mechanical sub-systems within an optics enclosure cooled to precisely -30°C in order to improve sensitivity in the near-infrared. It supports up to three client science instruments, including the first-light InfraRed Imaging Spectrograph (IRIS). Powering NFIRAOS is a Real Time Controller that will process the signals from six laser wavefront sensors, one natural guide star pyramid WFS, up to three low-order on-instrument WFS and up to four guide windows on the client instrument’s science detector in order to correct for atmospheric turbulence, windshake, optical errors and plate-scale distortion. NFIRAOS is currently preparing for its final design review in late June 2018 at NRC Herzberg in Victoria, British Columbia in partnership with Canadian industry and TMT.

HARMONI is a visible and near-infrared integral field spectrograph equipped with two complementary adaptive optics systems, fully integrated within the instrument. A Single Conjugate AO (SCAO) system offers high performance for a limited sky coverage and a Laser Tomographic AO (LTAO) system provides AO correction with a very high sky-coverage. While the deformable mirror performing real-time correction of the atmospheric disturbances is located within the telescope itself, the instrument contains a suite of state-of-the-art and innovative wavefront sensor systems. Laser guide star sensors (LGSS) are located at the entrance of the instrument and fed by a dichroic beam splitter, while the various natural guide star sensors for LTAO and SCAO are located close to the science focal plane. We present opto-mechanical architecture and design at PDR level for these wavefront sensor systems.

Laser Guide Stars are, in spite of their name, all but “stars”. They do not stand at infinite distance, neither on a plane. If fired from the side of a large telescope their characteristics as seen from various points on the apertures changes dramatically. As they extend in a 3D world, there is need of a WFS that deploy in a similar 3D manner, in the conjugated volume, resembling the approach that MCAO required long time ago to overcome the usual limitations of conventional AO. We describe a class of a novel kind of WFS that employ a combination of refraction and reflection, such that they can convey the light from an LGS into a limited number of pupils, making the device compact, doable with a single piece of glass, and able to feed a minimum sized format detector where the information is collected maximizing the information depending from which part of the LGS the light is coming from, and on which portion of the telescope aperture the light is landing. They represent, in our opinion, the best-known adaptation of the pyramid WFS for NGS to the LGS world. As in the natural reference case the practical advantages come along with some fundamental advantages. Being a pupil plane WFS with the perturbator placed on the (3D) loci of focus of the various portions of the source of light they have the potentiality to extend WFS to a number of issues, including the ability to sense the islands effect, where non-contiguous portions of the main apertures are optically displaced. Further to their description and the main recipes we speculate onto possible variations on cases where the LGS is fired from the back of the secondary mirror and we exploit some potential features when implementing onto an extremely large aperture.

Next-generation extremely large telescopes will be equipped with adaptive optics systems that use laser guide stars produced by resonant excitation of mesospheric sodium. The wavefront sensing of these systems could be enhanced by measurements of the vertical density profile of the mesospheric sodium along the line of sight, i.e. the sodium profile producing the LGS itself. Normally in AO system a few percent ( 3%) of the light from the LGS can be retrieved as leftover from the dichroic or the optics feeding the LGS WFS. This light, filtered and sent to a photon counter could be used for retrieving sodium density profiles. One approach is to partially modulate the intensity of the continuous wave lasers with a pseudo-random binary sequence of pulses. The sodium density profile can then be retrieved by cross-correlation of the measured LGS flux with the modulation sequence. With sufficient return flux, this technique can provide profiles every few seconds, useful for matching filters applied on elongated LGS, and can provide the centroid of the sodium layer profile, needed for the adaptive optics proper focus offset corrections. We have tested the continuous wave lidar concept by making simultaneous measurements using the modulation technique and a conventional lidar system, which provides the 'truth' in the comparison of the profiles. The experiments were conducted using the ESO Wendelstein laser guide star unit and the 6 m Large Zenith Telescope's sodium lidar system, located near Vancouver, Canada. This paper describes the experiment and presents some preliminary results. The possible implementation and potential performance of this technique for extremely large telescopes will be discussed.

The HIRES-ELT instrument foresees an observing mode that delivers integral field high resolution spectroscopy with spatial sampling down to the diffraction limit of the ELT telescope. The IFU-SCAO module presented here is sub-system of the front-end of HIRES-ELT that includes two modules: SCAO and IFU. The first is the wavefront sensor, based on a pyramid beam-splitter, that provides the guiding on the reference star and the analysis of the incoming wavefront; the second is the module that transforms the incoming f/17.7 light beam from the telescope to the appropriate f/numbers to feed the spectrometer fibers-array with the required spatial scale. In this paper, we will present the SCAO optical design to allow the exoplanet atmosphere detection in reflection. To achieve this goal, we studied a feasible pyramid wavefront sensor to be inserted in a sliding arm of the HIRES front end. The CCD camera is based on a CCD220 chip in which will be imaged the telescope pupil, sampled with a 90x90 sub-aperture grid. A total of 4089 Karhunen-Loeve modes have been generated and used to close an end-to-end simulation. The AO loop runs up to 1000 KHz and it allows to shrink the PSF to the diffraction limits of the telescope ant to achieve Strehl Ratio (SR) above 70% in best seeing case up to magnitude 15 in H-band and a SR permanently above 40%, same band, up to magnitude 14 in case of median seeing. For λ=1600nm the 50% of energy is reached before 1 λ/D for all the plotted I-magnitude under the best seeing conditions. Under Median seeing conditions, the 50% is reached before 2λ/D up to I-mag 13. For λ=1000nm instead, we reach the 50% of encircled energy before a radius of 2λ/D for I-mag less than 14 and after 5λ/D for I-mag greater than 15 in the best seeing case. For each IFU spatial sampling and resolution, we can reach a contrast of 10³ at a distance of 4 spaxels from central peak.

HCIPy is a package written in Python for simulating the interplay between wavefront control and coronagraphic systems. By defining an element which merges values/coefficients with its sampling grid/modal basis into a single object called Field, this minimizes errors in writing the code and makes it clearer to read. HCIPy provides a monochromatic Wavefront and defines a Propagator that acts as the transformation between two wavefronts. In this way a Propagator acts as any physical part of the optical system, be it a piece of free space, a thin complex apodizer or a microlens array. HCIPy contains Fraunhofer and Fresnel propagators through free space. It includes an implementation of a thin complex apodizer, which can modify the phase and/or amplitude of a wavefront, and forms the basis for more complicated optical elements. Included in HCIPy are wavefront errors (modal, power spectra), complex apertures (VLT, Keck or Subaru pupil), coronagraphs (Lyot, vortex or apodizing phase plate coronagraph), deformable mirrors, wavefront sensors (Shack-Hartmann, Pyramid, Zernike or phase-diversity wavefront sensor) and multi-layer atmospheric models including scintillation). HCIPy aims to provide an easy-to-use, modular framework for wavefront control and coronagraphy on current and future telescopes, enabling rapid prototyping of the full high-contrast imaging system. Adaptive optics and coronagraphic systems can be easily extended to include more realistic physics. The package includes a complete documentation of all classes and functions, and is available as open-source software.

MAORY is the Multi-conjugate Adaptive Optics module for the Extremely Large Telescope and it will be located on the Nasmyth platform of the telescope to feed scientific instruments. MAORY will re-image the telescope focal plane providing multi-conjugate adaptive optics correction of the wavefront distortion induced by the atmosphere. The system is based on six laser guide stars and three natural guide stars for sensing the wavefront distortion and three deformable mirrors for correcting it. We will show the current status of the preliminary design of the Real Time Computer in charge of carrying out all the calculations based on the measurements of the guide stars wavefront sensors. The hard real time (primary) loops are in charge of controlling the deformable mirrors and the lasers jitter compensation while the soft real- time (secondary) loops are in charge of updating the primary loops parameters as well as measuring or estimating the atmospheric parameters and the system performance. Telemetry data management/recording and calibration are the other tasks carried out by the real time computer.

The new generation of ground-based telescopes relies on real-time adaptive optics systems to compensate for atmospheric perturbations arising during the imaging process. Pyramid wavefront sensors are planned to be part of many instruments currently under development for ELT-sized telescopes. The high number of correcting elements to be controlled in real-time and the segmented pupils of the ELTs lead to unprecedented challenges posed to the control algorithms. Based on various (approximate) models, several algorithms were developed in the last decades for linear and non-linear wavefront correction from pyramid sensor data. Among those, we emphasize interaction-matrix-based approaches, Fourier domain methods, iterative algorithms, and algorithms based on the inversion of the Finite Hilbert transform. We briefly present the core ideas of the algorithms and provide the necessary theoretical background like, e.g., the Fourier domain filters, or the direct inversion formulas. We give a detailed comparison of the presented methods with respect to underlying pyramid sensor models, the computational complexities, and reconstruction qualities. The performance of our algorithms is demonstrated in the context of an XAO system on the EPICS instrument and a SCAO system on the METIS instrument on the ELT. In the simulations, realistic features as the ELT spiders and the hexagonal M4 geometry are partially taken into account.

The M4 mirror is the 4th mirror in the optical train of E-ELT telescope and is the one committed for the turbulence and wind shaking correction. The voice coil technology has been proven to be very interesting in terms of performance and fault tolerance in the past projects (LBT, Magellan, VLT) and it can guarantee high stroke and high correction speed joined to high precision and stability. In this paper, we will we will simulate the behavior of the system with four different seeing conditions giving a good representation of most the observing night typical cases. The simulation code allows to apply or not a bound to the forces of each M4 actuator used for the turbulence correction in order to fully characterize not only the maximum correction capabilities of the system but also the performance degradation in case of limited actuator capabilities applicable. To fully explore this second point, we suggested a modal cut algorithm which can be used as guideline for a smart thresholding system.

MAORY is the Multi-Conjugate Adaptive Optics module for the European ELT. It will provide a wide-field correction for the first-light instrument MICADO. The Low-Order wavefront modes will be sensed on 3 Natural Guide Stars with Shack-Hartmann Wavefront Sensors, so-called the LO WFS. In the presented work, we focus on the numerical study of the main aspects that depend on the LO WFS design and operational use: low-order sensing performance and sky coverage.

The COMPASS platform was designed to meet the need for high-performance for the simulation of AO systems. Taking advantage of the specific hardware architecture of the GPU, the COMPASS tool allows the AO scientist to obtain adequate execution speeds and to conduct large simulation campaigns scaled to the E-ELT dimensioning for a variety of AO flavors from SCAO to MOAO. On the latest GPU architecture (NVIDA Volta), execution speeds of several hundreds of short exposure PSF per second can be achieved for a SCAO system on the E-ELT, making the COMPASS platform a real-time end-to-end simulation tool. In this paper, we provide a full description of the critical physical models used in the simulation pipeline, review a range AO system configurations that can be addressed with COMPASS and report on the time to solution obtained for this systems. Scalability over multiple GPUs and multiple generations of GPUs is also discussed.