Real-time control (RTC) is pivotal for any Adaptive Optics (AO) system, including high-contrast imaging of exoplanets and circumstellar environments. It is the brain of the AO system, and what wavefront sensing and control (WFS&C) techniques need to work with to achieve unprecedented image quality and contrast, ultimately advancing our understanding of exoplanetary systems in the context of high contrast imaging (HCI). Developing WFS&C algorithms first happens in simulation or a lab before deployment on-sky. The transition to on-sky testing is often challenging due to the different RTCs used. Sharing common RTC standards across labs and telescope instruments would considerably simplify this process. A data architecture based on the interprocess communication method known as shared memory is ideally suited for this purpose. The CACAO package, an example of RTC based on shared memory, was initially developed for the Subaru- SCExAO instrument and now deployed on several benches and instruments. This proceeding discusses the challenges, requirements, implementation strategies, and performance evaluations associated with integrating a shared memory-based RTC. The Santa Cruz Extreme AO Laboratory (SEAL) bench is a platform for WFS&C development for large groundbased segmented telescopes. Currently, SEAL offers the user a non-real-time version of CACAO, a shared-memory based RTC package initially developed for the Subaru-SCExAO instrument, and now deployed on several benches and instruments. We show here the example of the SEAL RTC upgrade as a precursor to both RTC upgrade at the 3-m Shane telescopes at Lick Observatory (Shane-AO) and a future development platform for the Keck II AO. This paper is aimed at specialists in AO, astronomers, and WFS&C scientists seeking a deeper introduction to the world of RTCs.
Recent work by Oberti+22 argued and showed that classical astronomical adaptive-optics tomography performance can be further improved by carefully designing and configuring the system to encompass and exploit any built-in super-resolution (SR) capabilities.
Our goal now is to further materialise the concept by outlining the key models to compute SR-enabling tomographic reconstructors for AO.
For that we assume the form of a review paper where we (i) clarify how model-and-deploy static reconstructors arise naturally from the solution of the inverse problem and how to make them cope with closed-loop systems, (ii) how this solution is obtained as a limiting-case of a properly-conceived optimal stochastic control problem, (iii) review the two forms of the minimum-mean-squared-error (MMSE) tomographic reconstructors, highlighting the necessary adaptations to accommodate super-resolution, (iii) review the implementation in either dense-format vector-matrix-multiplication or sparse iterative forms and (iv) discuss the implications for runtime and off-line real-time implementations.
We illustrate our examples with simulations/on-sky results when possible for 10m and 40m-scale systems.
MAVIS passed the Preliminary Design Review in March 2023 and kick started its phase C early June. We are aiming at a Final Design Review in December 2024. I will report on the state of MAVIS design, as well as general project updates, schedule, procurement, risks. We are working on early procurement (Long Lead Item review held on October 2023) as well as on a number of prototype activities I will report on.
ULTIMATE-Subaru is the next generation wide-field near-infrared instrument for the Subaru Telescope, assisted by Ground-Layer Adaptive Optics (GLAO). The GLAO system is required to provide ∼0.2 arcsec image quality in FWHM at K band (2.2μm) uniformly over 14×14 arcmin2 field of view, with more than 90% sky-coverage. In previous studies of the GLAO system, we assumed the use of global shutter readout for the WFS detector. However, the current design of the GLAO WFS system uses the CMOS cameras employing rolling shutter readout. We have implemented the rolling shutter readout in the end-to-end numerical simulation according to the current design of the GLAO WFS system and update the GLAO performance evaluation. We also evaluate the temporal error with lower frame rate of the NGS WFS that is required to keep the GLAO performance with faint NGSs.
The MCAO-Assisted Visible Imager and Spectrograph (MAVIS) will utilise the Adaptive Optics Facility of the ESO Very Large Telescope, UT4. In order to fully harness the resolving power of an 8 m telescope in the visible spectrum, the AO system of MAVIS must adhere to a tight wavefront error budget. The demanding performance requirements flow into all aspects of the MAVIS design, not the least of which is the wavefront estimation strategy, leveraging tomographic turbulence measurements from 3 natural guide stars and 8 laser guide stars, all coupled to Shack Hartmann wavefront sensors. In this paper, we summarise the wavefront estimation processes proposed for MAVIS. In a companion paper, we discuss the LGS WFS design.
The MCAO-Assisted Visible Imager and Spectrograph (MAVIS) is an instrument that will provide an unprecedented level of imaging and spectroscopy with the highest visible angular resolution provided by any ground or space-based telescope. Operating at a wavelength range of .370 to .950um, MAVIS will be installed on the Nasmyth platform A of the ESO Yepun one of the Very Large Telescopes (VLT) as a general-purpose instrument with an angular resolution two to three times better than that of the Hubble Space Telescope. MAVIS will take advantage of the 4 lasers in the VLT Adaptive Optics Facility (AOF) with an added upgrade of the facility. This upgrade splits each of four lasers into pairs that generate the eight laser guide stars (LGS) used to feed the wavefront sensors (WFS). The MAVIS LGS WFS carousel is situated in the MAVIS Adaptive Optics Modules (AOM) where the 589nm laser light is split from the incoming beam before the instrument derotator. The LGS WFS module consists of a focuser to adjust for the altitude of the sodium layer and a rotating carousel that houses the eight LGS WFS. In this paper, we present the final design of the optical and mechanical components of the field derotating carousel, LGS WFS optics, and cameras. We introduce the simulations and models that continue to constrain and improve the performance of the design.
The Laser Tomography Adaptive Optics (LTAO) system for the Giant Magellan Telescope (GMT) will be the first laser guide star adaptive optics (LGS AO) wavefront control for the GMT, aimed at pushing the boundaries of astronomical observations beyond the limits of natural guide star (NGS) operations. The Australian National University is leading the design of some of the largest work packages in the GMT LTAO project, including the GMTIFS on-instrument wavefront sensor, LTAO LGS wavefront sensors, and the Laser Guide Star System (LGSS). Central to the LTAO system is the Laser Guide Star Subsystem (LGSS), responsible for creating a Laser Guide Star (LGS) asterism adjustable between 25 to 60 arcsec and centred on the science target. The LGSS comprises six Laser Guide Star Units (LGSU), each emitting a laser beam with precise spectro-temporal and spatial characteristics. The LGSU includes a Laser System, a Beam Conditioning and Diagnostic System (BCDS), a Laser Launch Telescope (LLT), and a LGS Unit Control System (LGSU CS). These components collectively ensure accurate pointing and focusing of the laser beam on the sky. This paper provides a comprehensive update on the re-assessment and redesign of the LGSS for the GMT, a collaborative effort reignited at the Australian National University after a ten-year hiatus in design work. The LGSS design is ready to re-attain the Preliminary Design level, after integrating interface changes that have evolved at the telescope since the Preliminary Design Review took place in 2013. In order to take advantage of advances made in the field over the past 10 years, the study investigates the feasibility of a shared launch for the GMT LTAO system and also re-evaluates the number of lasers required to generate the 6 LGS asterism.
Most of the current wavefront sensors used in adaptive optics systems estimate the phase of the wavefront indirectly by measuring the local gradients. In strong turbulence the AO correction decreases dramatically, meaning poor wavefront reconstruction. This is due to insufficient wavefront spatial sampling and large signal amplitude variations induced by scintillation, which reduce the accuracy of centroiding algorithms. Direct wavefront measurements, instead of its derivatives, with adequate spatial sampling are ideally suited. Interferometric techniques may be used in alternative to slope-based, or curvature-based wavefront sensors. In this work, a novel design of a point diffraction interferometer (PDI) wavefront sensor is presented which aims to optimise the light throughput and dynamic range while keeping its high sensitivity. This design is an optimised PDI wavefront sensor with a central pinhole. The modelling of this sensor using numerical propagation with Fourier optics is presented. A framework has been established to retrieve the phase reversing the interferometric process, which differs from traditional methods which typically use an off-axis pinhole or phase-stepping. These results look promising showing accurate phase retrieval in a variety of conditions. Ultimately, to overcome the non-linearity of the PDI, machine learning will be used to retrieve the phase and perform prediction. Our preliminary results on the use of machine learning for phase retrieval are also presented.
ULTIMATE-Subaru is the next-generation facility instrument program of the Subaru Telescope which will extend the existing Subaru’s wide-field survey capability to the near-infrared wavelength. The ULTIMATE-Subaru instrument suite includes Ground-Layer Adaptive Optics (GLAO) and wide-field near-infrared instruments, aiming to provide ∼0.2 arcsec image size at K band (2.2 μm) over 20 arcmin diameter field of view at the Cassegrain focus. The planned first light instrument is a Wide-Field Imager (WFI), which covers a 14 × 14 square arcmin field of view from 0.9 to 2.5 μm in wavelength. GLAO and WFI are currently in the final design phase, aiming to start the commissioning observations at the telescope in 2028. In parallel to the development for ULTIMATE wide-field instruments, there are ongoing activities to develop a narrow-field wide-band spectrograph (NINJA) together with a Laser Tomography AO system (ULTIMATE-START) utilizing the Adaptive Secondary Mirror and the Laser Guide Star Facility being developed for the GLAO system. In this presentation, an overview of the ULTIMATE-SUBARU instruments, their current status, and future prospects will be presented.
MCAO Assisted Visible Imager and Spectrograph (MAVIS) is a new instrument for ESO’s VLT AOF. MAVIS embarks an Adaptive Optics (AO) system to cancel the image blurring induced by atmospheric turbulence. The latency and computational load induced by the system dimensioning led us to design a new software and hardware architecture for the Real Time Controller (RTC). Notably, the COSMIC framework harnesses GPUs for accelerated computation and is adept at scaling across multiple processes without overhead using shared memory. Employing a graph-based architecture where operations are intuitively represented as nodes. It aims at simplifying design, implementation, testing and integration by relying on robust concepts and useful tools. Recent updates have further enhanced its versatility, cementing its potential as a future-proof, extensible framework for AO advancements and their development process.
As a faint-source cryogenic near-infrared spectrograph, GMTIFS requires a cold pupil stop, a Cold Stop, to reject parasitic thermal emission from outside the telescope pupil. For the GMT this requires a rotating segmented Cold Stop within the GMTIFS cryostat. The decentre accuracy achievable for the Cold Stop due to flexure under variable gravitational load at the GMT folded port Gregorian focus is a defining parameter for the Cold Stop under/oversizing. Under ideal circumstances, decentre accuracy should be within ±25 µm, the pupil image accuracy set by diffraction from the GMTIFS science field stop and relay foreoptics. The GMTIFS optical concept is based on elastic flexure of the optical table support structure suspended on trusses with global flexure corrected via telescope pointing. However, understanding the differential flexure residual between multiple internal focal and pupil planes requires modelling the motion of the full supported structure. This work explores the methods undertaken to simulate the mechanical stability of the Cold Stop in the context of the whole GMTIFS instrument, exploring how the kinematic mounting, cryostat, trusses, optical table and optics have a cumulative effect on Cold Stop motion. This analysis leads to a refinement of mechanical design across these subsystems, informing the final Cold Stop design and error budget.
MAVIS (the MCAO-Assisted Visible Imager and Spectrograph), planned for the VLT Adaptive Optics Facility, represents an innovative step in Multi-Conjugate Adaptive Optics (MCAO) systems, particularly in its operation at visible wavelengths and anticipated contributions to the field of astronomical astrometry. Recognizing the crucial role of high-precision astrometry in realizing science goals such as studying the dynamics of dense starfields, this study focuses on the challenges of advancing astrometry with MAVIS to its limits, as well as paving the way for further enhancement by incorporating telemetry data as part of the astrometric analysis. We employ MAVISIM, Superstar, and DAOPHOT to simulate both MAVIS imaging performance and provide a pathway to incorporate telemetry data for precise astrometry with MAVIS. Photometry analyses are conducted using the Superstar and DAOPHOT platforms, integrated into a specifically designed pipeline for astrometric analysis in MCAO settings. Combining these platforms, our research aims to elucidate the impact of utilizing telemetry data on improving astrometric precision, potentially establishing new methods for ground-based AO-assisted astrometric analysis. This endeavor not only sheds light on the capabilities of MAVIS but also paves the way for advancing astrometry in the era of next-generation MCAO-enabled giant telescopes.
Natural Guide Star (NGS) wavefront sensors (WFS) play a crucial role in multi-conjugate adaptive optics systems by detecting low-order aberrations that laser guide stars cannot measure. In the framework of MAVIS, we plan to use the light from three NGSs to correct the tip-tilt and low-order errors of the wavefront. In this work, we conduct the analysis of the distortions caused by mid-spatial frequency figure errors of the optical surfaces in the NGS WFS channel of the adaptive optics module of MAVIS. These distortions, stemming from component imperfections, can significantly impact wavefront measurements and, consequently, the plate scale in the image plane of the entire instrument. We analyse their influence on the plate scale variations during tracking. Our study quantifies the effect, shedding light on the impact of non-common path distortions between the NGS WFS and the scientific instruments on plate scale variations, ultimately contributing to optimising the MAVIS performance.
We develop and evaluate a new approach to phase estimation for observational astronomy that can be used for accurate point spread function reconstruction. Phase estimation is required where a terrestrial observatory uses an adaptive optics (AO) system to assist astronomers in acquiring sharp, high-contrast images of faint and distant objects. Our approach is to train a conditional adversarial artificial neural network architecture to predict phase using the wavefront sensor data from a closed-loop AO system. We present a detailed simulation study under different turbulent conditions, using the retrieved residual phase to obtain the point spread function of the simulated instrument. Compared to the state-of-the-art model-based approach in astronomy, our approach is not explicitly limited by modeling assumptions, e.g., independence between terms, such as bandwidth and anisoplanatism—and is conceptually simple and flexible. We use the open-source COMPASS tool for end-to-end simulations. On key quality metrics, specifically the Strehl ratio and Halo distribution in our application domain, our approach achieves results better than the model-based baseline.
The MCAO Assisted Visible Imager and Spectrograph (MAVIS) is currently in preliminary design for the ESO VLT. The instrument will provide multi-conjugate adaptive optics correction over a wide field of 30”x30”, feeding the visible part of the spectrum (from 370 to 1000nm) to an imager and a spectrograph. The Adaptive Optics Module (AOM) of MAVIS implements two deformable mirrors, composed by more than 2000 actuators each, and includes a Laser Guide Star (LGS) and a Natural Guide Star (NGS) wavefront sensor for the tomographic reconstruction and correction of the atmospheric turbulence. Moreover, it provides other key functionalities like atmospheric dispersion compensation and field de-rotation, delivering a corrected diffraction-limited 30”x30” focal plane to three output ports: one for the imager, one for the spectrograph and one for visiting instruments. In this paper we describe the current optical configuration of the AOM, and we report the results of the analyses conducted to evaluate the expected optical performance of the system. The analyses include simulations for the manufacturing and alignment tolerances, sensitivity to mid-spatial frequency figure errors and their impact to astrometry.
We develop and evaluate a new approach to phase estimation for observational astronomy that can be used for accurate point spread function reconstruction. Phase estimation is required where a terrestrial observatory uses an Adaptive Optics (AO) system to assist astronomers in acquiring sharp, high-contrast images of faint and distant objects. Our approach is to train a conditional adversarial artificial neural network architecture to predict phase using the wavefront sensor data from a closed-loop AO system. We present a detailed simulation study under different turbulent conditions, using the retrieved residual phase to obtain the point spread function of the simulated instrument. Compared to the state-of-the-art model-based approach in astronomy, our approach is not explicitly limited by modelling assumptions—e.g. independence between terms, such as bandwidth and anisoplanatism—and is conceptually simple and flexible. We use the open source COMPASS tool for end-to-end simulations. On key quality metrics, specifically the Strehl ratio and Halo distribution in our application domain, our approach achieves results better than the model-based baseline.
The MCAO Assisted Visible Imager and Spectrograph (MAVIS) is currently in preliminary design for the ESO VLT in Chile, and is set to deliver diffraction limited science in V-band over a wide (30”x30”) field of view. In order for MAVIS to capitalise on its high angular resolution over a large science field, a sensitive astrometric calibration process will be employed. The stringent requirements on this calibration process require the development of an astrometric calibration technique which is insensitive to manufacturing errors in the calibration mask, while still able to detect a broad range of distortions present in the MAVIS optical path. We derive one such calibration method along with simulations in the MAVIS context, using the open-source MAVISIM tool with realistic errors present.
It is common practice in adaptive optics to use CCD detectors with global shutter readout for wavefront sensing. sCMOS detectors with rolling shutter readout are often not considered due to image distortion when the object is moving at high speed. However, sCMOS detectors have the potential to achieve lower readout noise, larger format, and lower cost. Therefore, we investigate the effect of rolling shutter readout in the context of the laser guide star wavefront sensors of ULTIMATE-Subaru, a Ground Layer Adaptive Optics project at the Subaru telescope. In the case of a laser guide star wavefront sensor, the wavefront tip-tilt component is filtered out in the measurement due to the tip-tilt indetermination effect. With the rolling shutter readout, the tip-tilt component can alias onto the higher-order wavefront components, it becomes a problem for the wavefront measurement. Firstly, we identify the particular modes that are aliased onto, as well as the frequency response of this aliasing. As a result, it is confirmed that when the oscillation frequency of tip-tilt is faster than about 10% of the sampling frequency of the detector, it is partially measured as higher-order components such as coma and trefoil. We also conduct a wavefront measurement experiment using the ORCA-Flash4.0 v2 sCMOS detector manufactured by Hamamatsu Photonics. The experiment with the optical system shows consistent results as the simulation. Finally, we estimate the effect of aliasing from the tip-tilt components of the atmospheric turbulence, telescope vibration, and laser guide star jitter using a end-to-end adaptive optics simulation.
Real-time segment phasing is non-trivial in giant segmented mirror telescopes, as slope-based wavefront sensing methods are blind to segment piston if the gaps between segments are sufficiently large. In the GMT, this is certainly the case, and many solutions have been proposed which require additional wavefront sensing hardware and added optomechanical complexity. We propose a novel sequential phase-diversity method which requires only a time-sequence of closed-loop tip-tilt wavefront sensor images.
MAVIS will be part of the next generation of VLT instrumentation and it will include a visible imager and a spectrograph, both fed by a common Adaptive Optics Module. The AOM consists in a MCAO system, whose challenge is to provide a 30” AO-corrected FoV in the visible domain, with good performance in a 50% sky coverage at the Galactic Pole. To reach the required performance, the current AOM scheme includes the use of up to 11 reference sources at the same time (8 LGSs + 3 NGSs) to drive more than 5000 actuators, divided into 3 deformable mirrors (one of them being UT4 secondary mirror). The system also includes some auxiliary loops, that are meant to compensate for internal instabilities (including WFSs focus signal, LGS tip-tilt signal and pupil position) so to push the stability of the main AO loop and the overall performance. Here we present the Preliminary Design of the AOM, which evolved, since the previous phase, as the result of further trade-offs and optimizations. We also introduce the main calibration strategy for the loops and sub-systems, including NCPA calibration approach. Finally, we present a summary of the main results of the performance and stability analyses performed for the current design phase, in order to show compliance to the performance requirements.
The MCAO Assisted Visible Imager and Spectrograph (MAVIS) is a new visible instrument for ESO Very Large Telescope (VLT). Its Adaptive Optics Module (AOM) must provide extreme adaptive optics correction level at low galactic latitude and high sky coverage at the galactic pole on the FoV of 30arcsec of its 4k × 4k optical imager and on its monolithic Integral Field Unit, thanks to 3 deformable mirrors (DM), 8 Laser Guide Stars (LGS), up to 3 Natural Guide Stars (NGS) and 11 Wave Front Sensors (WFS). A careful performance estimation is required to drive the design of this module and to assess the fulfillment of the system and subsystems requirements. Here we present the work done on this topic during the last year: we updated the system parameters to account for the phase B design and for more realistic conditions, and we produced a set of results from analytical and end-to-end simulations that should give a as complete as possible view on the performance of the system.
MAVIS (the MCAO Assisted Visible Imager & Spectrograph) will be driven by a high performance real-time control (RTC) system relying on cutting edge hardware and software technologies, including the hard real-time pipeline as well as the supervisory and tightly coupled telemetry sub-systems. To meet the extremely challenging requirements of a complex instrument like MAVIS, this forward looking implementation of the COSMIC platform is designed to support, end-to-end, a wide range of control schemes, from classical model-based approaches up to modern data-driven methodologies. In this paper, we will review the design and prototyping activities being led during phase B of the project.
KEYWORDS: Visible radiation, James Webb Space Telescope, Observatories, Adaptive optics, Large telescopes, Spectrographs, Spatial resolution, Hubble Space Telescope, Telescopes
A consortium of several Australian and European institutes – together with the European Southern Observatory (ESO) – has initiated the design of MAVIS, a Multi-Conjugate Adaptive Optics (MCAO) system for the ground- based 8-m Very Large Telescope (VLT). MAVIS (MCAO-assisted Visible Imager and Spectrograph) will deliver visible images and integral field spectrograph data with 2-3x better angular resolution than the Hubble Space Telescope, making it a powerful complement at visible wavelengths to future facilities like the space-based James Webb Space Telescope and the 30 to 40m-class ground-based telescopes currently under construction, which are all targeting science at near-infrared wavelengths. MAVIS successfully passed its Phase A in May 2020. We present the motivations, requirements, principal design choices, conceptual design, expected performance and an overview of the exciting science enabled by MAVIS.
"We present initial results from the Multi-conjugate Adaptive-optics Visible Imager-Spectrograph Image Simulator (MAVISIM) to explore the astrometric capabilities of the next generation instrument MAVIS. A core scientific and operational requirement of MAVIS will be to achieve highly accurate differential astrometry, with accuracies on the order that of the extremely large telescopes. To better understand the impact of known and anticipated astrometric error terms, we have created an initial astrometric budget which we present here to motivate the creation of MAVISIM. In this first version of MAVISIM we include three major astrometric error sources; point spread function (PSF) field variability due to high order aberrations, PSF degradation and field variability due to tip-tilt residual error, and field distortions due to non-common path aberrations in the AO module. An overview of MAVISIM is provided along with initial results from a study using MAVISIM to simulate an image of a Milky Way-like globular cluster. Astrometric accuracies are extracted using PSF-fitting photometry with encouraging results that suggest MAVIS will deliver accuracies of 150µas down to faint magnitudes."
The MCAO Assisted Visible Imager and Spectrograph (MAVIS) is a facility-grade visible MCAO instrument, currently under development for the Adaptive Optics Facility at the VLT. The adaptive optics system will feed both an imager and an integral field spectrograph, with unprecedented sky coverage of 50% at the Galactic Pole. The imager will deliver diffraction-limited image quality in the V band, cover a 30" x 30" field of view, with imaging from U to z bands. The conceptual design for the spectrograph has a selectable field-of-view of 2.5" x 3.6", or 5" x 7.2", with a spatial sampling of 25 or 50 mas respectively. It will deliver a spectral resolving power of R=5,000 to R=15,000, covering a wavelength range from 380 - 950 nm. The combined angular resolution and sensitivity of MAVIS fill a unique parameter space at optical wavelengths, that is highly complementary to that of future next-generation facilities like JWST and ELTs, optimised for infrared wavelengths. MAVIS will facilitate a broad range of science, including monitoring solar system bodies in support of space missions; resolving protoplanetary- and accretion-disk mechanisms around stars; combining radial velocities and proper motions to detect intermediate-mass black holes; characterising resolved stellar populations in galaxies beyond the local group; resolving galaxies spectrally and spatially on parsec scales out to 50 Mpc; tracing the role of star clusters across cosmic time; and characterising the first globular clusters in formation via gravitational lensing. We describe the science cases and the concept designs for the imager and spectrograph.
The Learn and Apply reconstruction scheme uses the knowledge of atmospheric turbulence to generate a tomographic reconstructor, and its performance is enhanced by the real-time identification of the atmosphere and the wind profile. In this paper we propose a turbulence profiling method that is driven by the atmospheric model. The vertical intensity distribution of turbulence, wind speed and wind direction can be simultaneously estimated from the Laser Guide Star measurements. We introduce the implementation of such a method on a GPU accelerated non-linear least-squares solver, which significantly increases the computation efficiency. Finally, we present simulation results to demonstrate the convergence quality from numerically generated telemetry, the end-to-end Adaptive Optics simulation results, and a time-to-solution analysis, all based on the MAVIS system design.
The Learn and Apply tomographic reconstructor coupled with the pseudo open-loop control scheme shows promising results in simulation for multi-conjugate adaptive optics systems. We motivate, derive, and demonstrate the inclusion of a predictive step in the Learn and Apply tomographic reconstructor based on frozen-flow turbulence assumption. The addition of this predictive step provides an additional gain in performance, especially at larger wave-front sensor exposure periods, with no increase of online computational burden. We provide results using end-to-end numerical simulations for a multi-conjugate adaptive optics system for an 8m telescope based on the MAVIS system design.
The Adaptive Optics Module of MAVIS is a self-contained MCAO module, which delivers a corrected FoV to the postfocal scientific instruments, in the visible. The module aims to exploit the full potential of the ESO VLT UT4 Adaptive Optics Facility, which is composed of the high spatial frequency deformable secondary mirror and the laser guide stars launching and control systems. During the MAVIS Phase A, we evaluated, with the support of simulations and analysis at different levels, the main terms of the error budgets aiming at estimating the realistic AOM performance. After introducing the current opto-mechanical design and AO scheme of the AOM, we here present the standard wavefront error budget and the other budgets, including manufacturing, alignment of the module, thermal behavior and noncommon path aberrations, together with the contribution of the upstream telescope system.
This paper presents a preliminary analysis of the first results we have obtained from the adaptive optics systems built for EOS 1.8 m telescope at Mount Stromlo. This presentation focuses on the single-camera stereo-SCIDAR for monitoring the atmospheric seeing. We briefly summarize the system, describe its on-sky performance during commissioning, compare results to numerical simulations and evaluate the remaining challenges going into the future.
Space debris in low Earth orbit (LEO) below 1500 km is becoming an increasing threat to spacecrafts. To manage the threat, we are developing systems to improve the ground-based tracking and imaging of space debris and satellites. We also intend to demonstrate that it is possible to launch a high-power laser that modifies the orbits of the debris. However, atmospheric turbulence makes it necessary to use adaptive optics with such systems. When engaging with objects in LEO, the objects are available only a limited amount of time. During the observation window, the object has to be acquired and performance of all adaptive optics feedback loops optimised. We have implemented a high-level adaptive optics supervision tool to automatise time-consuming tasks related to calibration and performance monitoring. This paper describes in detail the current features of our software.
Adaptive Optics (AO) systems rely on atmospheric turbulence models in order to reduce the effect of wave-front aberrations on image quality. Due to the nature of turbulence, these models can exploit shift-invariant structures without a severe loss in generality. The resulting subset of possible state-matrices is efficiently characterised for identification using Quadratic Programming (QP). Additionally, the initial assumption of shift-invariance is relaxed in order to accommodate for the boundary effect of finite-pupils.
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