MORFEO is a post-focal adaptive optics module that forms part of the first light instrument suite for the Extreme Large Telescope (ELT). The project is now in the Final Design Phase. In this paper, we report the status of the project.
In the upcoming future the Adaptive Optics group of the Arcetri Observatory aims to integrate and operate two laboratory R&D facilities dedicated to explore new technologies for the operation of the next generation of 40m-class telescopes. In a nutshell they are aimed to: 1) to investigate the benefits of a dual-stage AO system for planet finding instruments (like ELT/PCS) and 2) the identification of a suitable sensor for the control of the piston error on the ELT and GMT. The participation of the Arcetri AO group to the STILES project granted the necessary funding and the perfect time frame to procure the key components required to implement these two facilities. In this paper we will introduce the two R&D facilities, detailing their layout in the laboratory and addressing the specific test cases they will be able to mimic for (e.g. sources, atmospheric conditions, telescope degrees-of-freedom, . . . ). We will then focus on the design of 2 key components of the benches: the custom-made segmented mirror for the AoPetalometer bench and the pyramid wavefront sensors for the AoCascading bench.
The Natural Guide-star Adaptive Optics (NGAO) mode of the Giant Magellan Telescope (GMT) is one of the two diffraction-limited AO modes under development by GMTO and its partner institutions. It will use the Adaptive Secondary Mirror (ASM) for wavefront correction, and a Natural Guide star Wavefront Sensor (NGWS) unit featuring two visible-light sensing channels to measure wavefront aberrations, including phasing errors between the seven segments of the GMT. The first NGWS channel features a modulated pyramid wavefront sensor (PWFS) and the second NGWS channel features a Holographic Dispersed Fringe Sensor (HDFS), which unambiguously detects segment piston errors as large as ~10 microns in wavefront. To test the performance of this novel wavefront sensing architecture, a prototype of the NGWS was built and integrated with the High Contrast AO Testbed (HCAT) and the MagAO-X system in the laboratories of the Center of Astronomical Adaptive Optics (CAAO) of the University of Arizona. The INAF Arcetri AO group designed and built the first NGWS channel, while GMTO designed and built the second NGWS channel in collaboration with CAAO. We report in this contribution the results of the laboratory experiments conducted over two two-week runs held in 2023 that demonstrate the capability of the NGWS to sense and correct for wavefront and phasing errors under the presence of mild atmospheric disturbances using the GMT NGAO control algorithms adapted to the testbed.
MORFEO is the multi-conjugate adaptive optics system of the Extremely Large Telescope (ELT). A key component of MORFEO is the the natural guide star (NGS) wavefront sensor (WFS) module that aims to implement the hardware and functionalities required to sense the lower orders of the atmospheric turbulence, integrating the tomographic reconstruction of the wavefront aberrations achieved in collaboration with the six laser guide stars (LGS) WFS. Currently, the final design of the NGS WFS sub-system is ongoing. In this paper we aim to update on the key aspects of the ongoing work regarding the optical and mechanical design and analyses, the electrical components selection and layout.
ANDES,the high resolution spectrograph for the ELT, will work both in seeing limited mode and with Adaptive Optics (AO) correction. ANDES-SCAO is a single conjugated AO system working with natural guide stars, feeding the IFU coupled to the YJH spectrograph. The main science goal of the ANDES AO mode is the characterization of the exo-planet atmosphere in reflected light. Hence, the driving technical requirement for the AO system is the PSF contrast. The level of achieved contrast determines the number of exo-planets on which the instrument will be able to detect bio-signatures. The key challenge for the achievement of high contrast is the control of M4 petalling. Here, we present the current status of the ANDES-SCAO design, approaching the ANDES preliminary design review scheduled in fall 2024.
In the past two years significant forward progress has been achieved in development of Adaptive Optics sensing and control technology needed for the observation modes of the Giant Magellan Telescope1. Most notable is the recent progress in demonstrating the accurate and stable control of segment piston in the diffraction-limited Natural Guide Star AO observation mode. Two NSF-funded testbeds have been successfully operated to validate the control algorithms for active optics, adaptive optics and segment piston in diffraction-limited observation. GMTO also built and operated wavefront sensor prototypes and integrated them with the testbeds. The testing has largely validated the wavefront sensor designs and has retired much of the fabrication and assembly risks. In parallel with the hardware demonstrations, significant progress has been achieved in both NGAO and LTAO control simulations verifying compliance with the required performance in each of these observation modes and thereby supporting the image quality budgets. In the area of design the GMTO Telescope Metrology Subsytem has passed its Preliminary Design Review and the conceptual design of the Adaptive Optics Test Camera has been completed. Finally, a Delta Preliminary Design phase for the LTAO hardware has begun.
The Giant Magellan telescope adaptive optics system will use two different diffraction-limited imaging modes. One of them is the Natural Guide Star Adaptive Optics mode (NGAO). NGAO uses a 7-segment ASM to provide wavefront correction and a single natural guide star coupled with a post focal wavefront sensor called the NGWS. The NGWS has two different channels: the main one featuring a high spatial sampling pyramid sensor dedicated to the fast frame rate correction of atmospheric turbulence and the second one featuring an Holographic Dispersed Fringe Sensor dedicated to phasing correction of the seven segments of the GMT. The Arcetri AO group, in collaboration with GMTO, designed and built a prototype of the NGWS. Arcetri AO group was in charge of providing the design, fabrication and testing of the pyramid wavefront sensor channel of the NGWS prototype that replicates all aspects of optical sensitivity including optical design, camera selection and data reduction of the final NGWS unit. The NGWS prototype was fully integrated at the University of Arizona in the High Contrast Adaptive Optics Testbed (HCAT) during summer 2023 and has been tested to demonstrate its capability to keep the segments of the GMT in phase during a high-performance AO loop. The paper focuses on the aspects of the integration and tests related to the pyramid sensor.
In the last decades, Adaptive Optics have gained a great importance in improving the observatories capabilities all over the world, and the complexity and dimensions of deformable mirrors have grown rapidly, making necessary the development of clever ways to perform their optical calibration. Here we propose the study of a procedure based on the accurate local calibration of the position sensors. This approach would have a huge impact on both time and cost with respect to actual approach, consisting in the measurement of the actuators influence functions in full aperture. After the development of a simulation tool, able to prove our idea, we will test the new approach on deformable mirrors which are now under production.
Morfeo (Multi-conjugate adaptive Optics Relay For ELT Observations) is an adaptive optics module able to compensate the wavefront disturbances affective the scientific observation. It will be installed on the straight-through port of the telescope Nasmyth platform to serve the first-light instrument MICADO and with the provision for a future second instrument. The module underwent the Preliminary Design Review in 2021 and is expected to be commissioned in 2029. In this paper we present a synthesis of the System Engineering approach adopted to manage the development of the instrument assessing the criticalities of phase B (preliminary design) and preliminary phase C (final design). We will discuss the evolution of the system engineering approach, identifying within the MBSE framework the evolution of the various modelling artefacts. towards the requirements. We will detail the criticalities of the system engineering with a particular focus onto the management of the interfaces between subsystems and external systems (Telescope, other instruments…).
The interferometric calibration and measurement of deformable mirrors for adaptive optics are often performed on complex optical system with spider arms. The spider shadows may divide the mirror surface into separate islands on the detector, so the interferometer fails in reconnecting them to a common phase value. The calibration measurements then suffer from such artificial differential pistons across islands, which is converted into a wrong actuator command and in general into a poor calibration. We review the effects of spider arms shadowing as experienced during the optical calibration of large format adaptive mirrors, such as the Large Binocular Telescope and Very Large Telescope ones; we describe the procedures that we tested to cope with these issues and their effectiveness; and we present a laboratory assessment of the effect of such a shadowing with a dedicated test setup. Our work is part of a preparatory activity for the optical test of the European Extremely Large Telescope adaptive mirror M4.
Enhanced Resolution Imager and Spectrograph is an instrument currently under commissioning at the Cassegrain focus of the Very Large Telescope UT4. Its mission is to replace the suite of instruments NAOS-CONICA and SINFONI and push to the edge the capabilities of this 8-meter class telescope, by leveraging the adaptive optics module. The instrument has been designed for maximum lifetime and reliability and minimum downtime. We will present the instrument constraints and our approach to the reliability, availability, and maintainability (RAM) analysis. We identified the main actors in the system, then for each of them, we compiled a database of reliability parameters in order to build-up the reliability diagram, describing the failure sources. Starting from this information, we computed the system-wide reliability parameters and compared them with the requirements by the customer. Such a scheme is very general and may be taken as an example of RAM analysis for astronomical instrumentation; it may be also customized for the needs of other projects. In the end, we summarize the lessons learned.
The Giant Magellan Telescope (GMT) Adaptive Optics (AO) systems feature a single conjugate natural guide star based AO system using the 7 deformable secondaries and a post focal wavefront sensor named NGWS (Natural Guide star Wavefront Sensor). The NGWS has two different channels: one featuring a high spatial sampling pyramid sensor dedicated to the fast frame rate correction of atmospheric turbulence and a second dedicated to the correct phasing of the 7 segments of the GMT telescope. The Arcetri AO group in collaboration with the GMT Organization (GMTO) and the University of Arizona (UA) is in charge of providing the design, fabrication and test of a prototype of the NGWS system that shall replicate all aspects of optical sensitivity including optical design, camera selection and data reduction. The prototype design starts from the baseline design for the NGWS that was provided by the Arcetri group in 2013. The prototype project Kick-off Meeting was held on April 16th 2021 and is foreseen to reach completion 34 months later. A first set of performance tests will be performed locally in Arcetri and the final prototype performance verification will happen at UA laboratories after installation of the unit on the High Contrast AO test bench developed by the AO group of UA. This final verification is scheduled for the summer of 2023. The paper reports about the prototype development work summarizing results of numerical simulation that lead to the chosen opto-mechanical design, main features and challenges of optical design for the two sensing channels.
The Giant Magellan Telescope’s primary and deformable secondary mirror are each composed of 7 segments. The Natural Guide Star (NGS) wavefront sensor has the critical task to keep these 7 segments in phase in addition to the classical Adaptive Optics (AO) correction. The baseline defined several years ago has two pyramid wavefront sensors working in the visible. The first one is used to close the AO loop (main channel), but it is not sensitive to differential pistons that are multiples of its central wavelength (λ1), leading to segment ejections. The second pyramid, sensing at a slightly higher wavelength, is then used as a slow ”truth sensor” (2nd channel) to derive the sign of a segment ejection and correct it by steps of λ1. However, the robustness of this solution with respect to noise and turbulence conditions is not satisfying. We are now in a prototyping phase, for which the first step is to improve the baseline or find an alternative design for the 2nd channel in order to gain robustness. One of the potential solutions is LIFT, a focal-plane wavefront sensor. By making use of the sensor at two different wavelengths, it is possible to derive an unambiguous differential piston measurement. In this work, we describe our piston control strategy and show the results of end-to-end simulations comprising the full AO loop and the 2nd channel correction at the faint end of the NGS mode.
One of the greatest technical challenges of the doubly-segmented Giant Magellan Telescope is the accurate and stable control of segment piston in the diffraction limited observation mode. To address this challenge, in collaboration with the University of Arizona, Smithsonian Astrophysical Observatory and the Istituto Nazionale di Astrofisica, GMTO is executing a project to optimize and validate segment piston control strategies and algorithms using a pair of testbeds. The testbeds provide disturbances to simulate atmospheric turbulence and differential atmospheric dispersion. In addition to the phasing demonstration, the testbeds offer the opportunity to validate hardware designs for the Acquisition & Guiding Wavefront Sensor (AGWS) and the Natural Guide Star Wavefront Sensor (NGWS) and to mitigate their fabrication and assembly risks. Significant progress is reported in the design of the AGWS and NGWS prototypes as well as preliminary test results from the testbeds.
The MAORY deformable mirrors are the wavefront correction system of the instrument and have to guarantee very high level performances. Given the intrinsic shapeless of a glass thin shell, such kind of systems need to be optically calibrated in order to act at maximum performances. In this paper we present our concept for the calibration of such large convex and concave mirrors.
KEYWORDS: Deformable mirrors, Calibration, Error analysis, Received signal strength, Manufacturing, Wavefronts, Adaptive optics, Temperature metrology, Finite element methods, Zernike polynomials
The deformable mirror are one of the key parts of MORFEO instrument when the system is working as multi conjugate wavefront corrector. However its stability is fundamental to guarantee a low wavefront error at the level of the MICADO focal plane when MICADO is acting in SCAO mode. In this paper we present our WFE constrains, the strategy and the analysis we performed to eventually guarantee the system inside the thermal specification stability.
The Deformable Mirrors are, with the wavefront sensors, the core of the adaptive optics system of MORFEO (formerly known as MAORY), the first light AO system for ELT. Such large deformable mirrors (about convex 930 and concave 1220 mm) and the large number of modes (about 900 and 1000 modes) will allow a fitting error below 40 nm RMS on the atmospheric turbulence layers which they are conjugated to with a worst seeing case of 1.5 arcsec. In this paper we will briefly present the status of the design and the performances reached.
We investigate the interferometric measure-ability of the silicon carbide Reference Body of the ELT adaptive
mirror M4. The sampling is technically challenging, because of the low fringes modulation due to poor surface
finish and to the extremely large number of holes in the aperture. We describe our approach to face and solve
such criticalities, based on laboratory experimentations with a Twyman Green interferometer on a dedicated
optical setup; we comment the feasibility of such measurement in a real environment and present in the end a
checklist to enable interferometer measurements in such unfavourable conditions.
MORFEO/MAORY is the post-focal adaptive optics instrument of the ELT. It is designed to provide the 53×53 arcsec field of view of MICADO with MCAO correction based on split-tomography, where the Low-Order modes are sensed by three NGS-based WFS. To maximize the sky-coverage the LO-WFS are 2×2 subapertures Shack- Hartmann sensors working in the H band, making use of the FREDA detectors. MAORY also implements 3 dedicated NGS-based truth sensors to measure at slow rate the true higher order atmospheric aberrations and to de-trend the LGS WFS measurements. These WFS work with the visible light of the NGS to feed a 10 × 10 SH sensor that makes use of the ALICE detector. Each unit of LOR WFS is provided with a couple of orthogonal linear stages to allow for the NGS acquisition in a 80 arcsec radius. The 3 LOR WFS are arranged at 120° geometry on a common support structure that rigidly connects them to MICADO and its rotator.
In this paper we present the status of the LOR WFS Module at the output of the MORFEO preliminary design review. We focus on the optomechanical arrangement of the subsystem highlighting the design choices and the analyses we carried out to verify its compliance to the requirements.
MORFEO (formerly known as MAORY) is a post-focal adaptive optics module that forms part of the first light instrument suite for the Extreme Large Telescope (ELT). The project passed the Preliminary Design Review in two stages in April and July 2021 and is now entering the Final Design Phase. In this paper we report the status of the project.
The paper describes the design of the NGS WFS sub-module of MAVIS, an instrument for the VLT UT4 that aims to provide diffraction limited imaging and spectroscopy at visible wavelengths. In this framework the NGS WFS provides means for the tomographic measurement of the lower-orders of the atmospheric turbulence allowing MAVIS to reach the required performances in terms of sky coverage and resolution. We present the optical design and performance of the NGS WFS probes and acquisition camera, the actuators embedded in the subsystem and their control hardware. Finally, we show the mechanical arrangement of the submodule.
ERIS is a new instrument currently under commissioning at Cassegrain focus of ESO VLT UT4. Its mission is to replace the NAOS-CONICA and SINFONI instruments to push to the edge the capabilities of this 8-meter class telescope thanks to his AO module by take full advantage of the new DSM (Deformable Secondary Mirror) and the artificial star builder facility (4LGSF - 4 Laser Guide Star Facility). The AO module have been built trying to maximize the lifetime and reliability and to minimize the downtime. In this paper we will present the constraint we were subjected and the approach we followed to perform the RAM (Reliability, Availability, Maintainability) analysis, comparing with what we experienced up to now and the lesson learned after the assembly and integration (AIV) process.
System engineering and project-team management are essential tools to ensure the project success and the Redmine is a valuable platform for the work organization and for a system engineered approach. We review in this work the management needs related to our project, and suggest the possibility that they fit to many research activities with a similar scenario: small team, technical difficulties (or unknowns), intense activity sprints and long pauses due to external schedule management, a large degree of shared leadership. We will then present our implementation with the Redmine, showing that the use of the platform resulted in a strong engagement and commitment of the team. The explicit goal of this work is also to rise, at least internally, the awareness about team needs and available organizational tools and methods; and to highlight a shareable approach to team management and small scale system engineering.
The ELT M4 is the telescope-facility adaptive unit for the European ELT. Final design and construction were awarded in 2015 to AdOptica, a consortium of Microgate and ADS International; on-site delivery is planned for 2024. The unit is based on a monolithic, structural reference body manufactured by Mersen Boostec. The flat thin mirror, controlled using the contactless voice-coil-motor based technology, is split in 6 segments produced by Safran Reosc. The M4 unit is ready for integration: we report here the results of the construction and component level testing, introducing also the forthcoming integration and system-level tests.
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