MICADO is a first light instrument for the Extremely Large Telescope (ELT), set to start operating later this decade. It will provide diffraction limited imaging, astrometry, high contrast imaging, and long slit spectroscopy at near-infrared wavelengths. During the initial phase operations, adaptive optics (AO) correction will be provided by its own natural guide star wavefront sensor. In its final configuration, that AO system will be retained and complemented by the laser guide star multi-conjugate adaptive optics module MORFEO (formerly known as MAORY). Among many other things, MICADO will study exoplanets, distant galaxies and stars, and investigate black holes, such as Sagittarius A* at the centre of the Milky Way. After their final design phase, most components of MICADO have moved on to the manufacturing and assembly phase. Here we summarize the final design of the instrument and provide an overview about its current manufacturing status and the timeline. Some lessons learned from the final design review process will be presented in order to help future instrumentation projects to cope with the challenges arising from the substantial differences between projects for 8-10m class telescopes (e.g. ESO’s VLT) and the next generation Extremely Large Telescopes (e.g. ESO’s ELT). Finally, MICADO's expected performance will be discussed in the context of the current landscape of astronomical observatories and instruments. For instance, MICADO will have similar sensitivity as the James Webb Space Telescope (JWST), but with six times the spatial resolution.
MICADO is the Multi-AO Imaging Camera for Deep Observations, a first light instrument for the Extremely Large Telescope (ELT). The instrument will be assisted by a Single-Conjugate Adaptive Optics (SCAO) system and the Multiconjugate adaptive Optics Relay For ELT Observations (MORFEO). MICADO can operate in the so-called standalone mode in the absence of MORFEO with the SCAO correction alone. The Relay Optics (RO), is the optical system relaying the ELT focal plane to an appropriate position inside the MICADO cryostat for that SCAO-only stand-alone observing mode. After successfully passing the Final Design Review (FDR), the manufacturing of the RO is in full swing. We present here the current status of the ongoing assembly, integration and verification campaign (AIV), together with its upcoming challenges. The RO consists of an optical bench made of carbon fiber reinforced plastic (CFRP), an optical assembly made of three flat, motorized tip-tilt-piston mirrors (M1, M5 and M6) and three powered mirrors (M2, M3 and M4) of up to ~500 mm in diameter, the MICADO calibration assembly (MCA) including its deployable unit with a flat mirror (MDU) and a cover to protect all opto-mechanical components on top of the bench. The fabrication of the mirrors has started, while the machining of the mirror mounts is well ahead. The optical bench, as well as all other CFRP parts have been ordered and the manufacturing is completed. In order to get optimum performance and minimal wavefront error (WFE), the mirrors are tested in their mounts before carrying out the final polishing operations. Therefore, all mirror mounts are scheduled to be delivered to the mirror vendor QED Optics by the end of 2024.
MICADO is the Multi-AO Imaging Camera for Deep Observations, the first light instrument for the Extremely Large Telescope (ELT). The instrument provides imaging, astrometric, spectroscopic and coronographic observing modes. MICADO will be assisted by a Single-Conjugate Adaptive Optics (SCAO) system and the Multiconjugate adaptive Optics Relay For ELT Observations (MORFEO). The instrument will provide a narrow (19”) and a wide (51”) Field of View. MICADO can operate in the so-called stand-alone mode in the absence of MORFEO with the SCAO correction alone. In this mode, the ELT focal plane is reimaged to the MICADO focal plane via the relay optics (RO). This subsystem consists of an optical bench made of carbon fiber reinforced plastic, the MICADO calibration assembly, a cover to protect all opto-mechanical components on top of the bench, and an optical assembly. The optical assembly of the RO consists of six mirrors, with diameters that go up to around 500 mm. Three of the mirrors are powered, and constitute a Three Mirror Anastigmat (TMA). To be compliant with wavefront error and pupil quality requirements, these mirrors must be aligned to within sub millimeter and sub arcminute tolerances. The remaining mirrors are flat motorized piston, tip-tilt mirrors for interface alignment. In this work, we present the procedure for the alignment of the optical elements of the RO. We present a proof of concept test using dummy mirrors within the already manufactured RO optics mounts, complemented with analyses that extends the results obtained from the test to evaluate the performance of the alignment, finding very promising results within expected tolerances.
HARMONI is the first light visible and near-IR integral field spectrograph for the ELT covering a large spectral range from 450nm to 2450nm with resolving powers from 3500 to 18000 and spatial sampling from 60mas to 4mas. It can operate in two Adaptive Optics modes - SCAO and LTAO - or with no AO. The project is preparing for Final Design Reviews. The laser Tomographic AO (LTAO) system provides AO correction with very high sky-coverage thanks to two systems: the Laser Guide Star Sensors (LGSS) and the Natural Guide Star Sensors (NGSS). LGSS is dedicated to the analysis of the wavefront coming from 6 laser guide stars created by the ELT. It is made of 6 independent wavefront sensor (WFS) modules mounted on a rotator of 600mm diameter to stabilise the pupil onto the microlens array in front of the detector. The optical design accepts elongated spots of up to 16 arcsec with no truncation using a CMOS detector from SONY. We will present the final optical and mechanical design of the LGSS based on freeform lenses to minimize the numbers of optical components and to accommodate for the diversity of sodium layer configurations. We will focus on rotator design, illustrating how we will move 1 tons with 90” accuracy in restrictive environment. Finally, we will present the strategy to verify the system in HARMONI context. The main challenge for the verification being how to test an AO system without access to the deformable mirror, part of the ELT.
MICADO is the Multi-AO Imaging Camera for Deep Observations, a first light instrument for the Extremely Large Telescope (ELT). The instrument will be assisted by a Single-Conjugate Adaptive Optics (SCAO) system and the Multi conjugate Adaptive Optics RelaY (MAORY). MICADO can operate in the so-called stand-alone mode in the absence of MAORY with the SCAO correction alone. Here, we present the opto-mechanical final design of the Relay Optics (RO), the optical system relaying the ELT focal plane to an accessible position of MICADO for that SCAO-only stand-alone observing mode. The RO consists of an optical bench made of carbon fiber reinforced plastic (CFRP), an optical assembly made of three flat, motorized tip-tilt-piston mirrors and three powered mirrors of up to ~500 mm in diameter, the MICADO calibration assembly and a cover to protect all opto-mechanical components on top of the bench. A 9-point whiffletree support, combined with a thermal compensation system is implemented for the critical flat mirror (M6), while a more simple 3- point support is employed for the other two flat mirror M1 and M5. The powered mirrors (M2, M3, M4) comprising the relay's three mirror anastigmat (TMA) are supported by V-shape mounts. The static and the dynamic performance of the MICADO RO are investigated through a detailed Finite Element Analysis (FEA), whose results are combined with a Zernike basis representation of the surface deformations performed in Zemax for assessing the optical performance. The variation of the mirror position due to the operational temperature drift Delta T and other disturbances, is also considered in an end-to-end simulation. The required overall wavefront error of 100 nm rms is fulfilled with the current design proposal. Additionally, the results of a motorized tip-tilt-piston mirror mount prototype are presented as well..
MICADO is the Multi-AO Imaging Camera for Deep Observations, a first light instrument for the Extremely Large Telescope (ELT). The instrument provides imaging, astrometric, spectroscopic and coronographic observing modes. MICADO will be assisted by a Single-Conjugate Adaptive Optics (SCAO) system and the Multi-conjugate Adaptive Optics RelaY (MAORY). The instrument will provide a narrow (19′′) and a wide (51′′) Field of View. MICADO can operate in the so-called stand-alone mode in the absence of MAORY with the SCAO correction alone. In this mode, the ELT focal plane is reimaged to the MICADO focal plane via the relay optics (RO). This subsystem consists of an optical bench made of carbon fiber reinforced plastic, the MICADO calibration assembly, a cover to protect all opto-mechanical components on top of the bench, and an optical assembly. The optical assembly consists of six mirrors, with diameters that go up to around 500 mm. Three of the mirrors are powered, and make a TMA. The remaining mirrors are flat motorized piston, tip-tilt mirrors for interface alignment. The nominal design provides a WFE below 25.3 nmRMS for the full FoV, and a high quality exit pupil. In this work, we present the optical design of the RO, and a comprehensive tolerance analysis. This includes alignment and manufacturing tolerances, mount-induced aberrations, warping of the RO bench, and the thermal behaviour of the complete subsystem, and looking at its effects on the WFE, and exit pupil quality. We have a compliant subsystem, which has been approved at FDR level.
Direct imaging instruments have the spatial resolution to resolve exoplanets from their host star. This enables direct characterization of the exoplanets atmosphere, but most direct imaging instruments do not have spectrographs with high enough resolving power for detailed atmospheric characterization. We investigate the use of a single-mode diffraction-limited integral-field unit that is compact and easy to integrate into current and future direct imaging instruments for exoplanet characterization. This achieved by making use of recent progress in photonic manufacturing to create a single-mode fiber-fed image reformatter. The fiber link is created with three-dimensional printed lenses on top of a single-mode multicore fiber that feeds an ultrafast laser inscribed photonic chip that reformats the fiber into a pseudoslit. We then couple it to a first-order spectrograph with a triple stacked volume phase holographic grating for a high efficiency over a large bandwidth. The prototype system has had a successful first-light observing run at the 4.2-m William Herschel Telescope. The measured on-sky resolving power is between 2500 and 3000, depending on the wavelength. With our observations, we show that single-mode integral-field spectroscopy is a viable option for current and future exoplanet imaging instruments.
The Multi-Core Integral-Field Unit (MCIFU) is a new diffraction-limited near-infrared integral-field unit for exoplanet atmosphere characterization with extreme adaptive optics (xAO) instruments. It has been developed as an experimental pathfinder for spectroscopic upgrades for SPHERE+/VLT and other xAO systems. The wavelength range covers 1.0 um to 1.6um at a resolving power around 5000 for 73 points on-sky. The MCIFU uses novel astrophotonic components to make this very compact and robust spectrograph. We performed the first successful on-sky test with CANARY at the 4.2 meter William Herschel Telescope in July 2019, where observed standard stars and several stellar binaries. An improved version of the MCIFU will be used with MagAO-X, the new extreme adaptive optics system at the 6.5 meter Magellan Clay telescope in Chile. We will show and discuss the first-light performance and operations of the MCIFU at CANARY and discuss the integration of the MCIFU with MagAO-X.
MICADO is the Multi-AO Imaging Camera for Deep Observations, a first light instrument for the Extremely Large Telescope (ELT). The instrument provides imaging, astrometric, spectroscopic and coronographic observing modes. MICADO will be assisted by a Single-Conjugate Adaptive Optics (SCAO) system and the Multi-conjugate Adaptive Optics RelaY (MAORY). The instrument will provide a narrow (19′′) and a wide (51”) Field of View. MICADO can operate in the so-called stand-alone mode in the absence of MAORY with the SCAO correction alone. Here, we present the opto-mechanical design of the Relay Optics (RO), the optical system relaying the ELT focal plane to an accessible position for MICADO using the SCAO-only stand-alone observing mode. The RO consists of an optical bench made of carbon fiber reinforced plastic (CFRP), an optical assembly made of three flat mirrors with motorized piston-tip-tilt mounts and three additional powered mirrors of up to ~500 mm in diameter, the MICADO calibration assembly, and a cover to protect all opto-mechanical components on top of the bench. A 9-point whiffletree support, combined with a thermal compensation system is implemented for the critical mirrors. The static and the dynamic performance of the MICADO RO are investigated through a detailed Finite Element Model (FEM), the results are combined with a Zernike basis representation of the mirror surface deformations performed in Zemax for assessing the optical performance.
The Multi-Core Integral-Field Unit (MCIFU) is a diffraction-limited near-infrared integral-field spectrograph designed to detect and characterise exoplanets and disks in combination with extreme adaptive optics (xAO) instruments. It has been developed by an extended consortium as an experimental path finder for medium resolution spectroscopic upgrades for xAO systems. To allow it to achieve its goals we manufactured a fibre link system composed of a custom integrated fiber, with 3D printed microlenses and an ultrafast laser inscribed reformatter. Here we detail the specific requirements of the fibre link, from its design parameters, through its manufacture the laboratory performance and discuss upgrades for the future.
The paper reports an overview of the preliminary optical design for the MICADO Relay Optics (RO) to enable early science observations of the instrument at the Extremely Large Telescope (ELT) with single-conjugate adaptive optics (SCAO). MICADO, the Multi-AO Imaging Camera for Deep Observations, is a first light imager, astrometric camera and spectrograph operating between 0.8 µm and 2.4 µm. The RO are based on a six mirror (6M) optical assembly that relays the telescope focal plane to an accessible position for the MICADO cryostat. The system includes three powered mirrors in a three-mirror-anastigmat configuration and three piston and tip- tilt flat mirrors for the alignment and the beam folding at the interfaces with the ELT and MICADO. This design represents an interesting example of optical performance optimization to achieve high performances optics both for the direct imaging channel and the pupil interface towards MICADO and the SCAO. The RO performances are analyzed and verified at a design level showing the compliance with the requirement specifications and the reliability of the design is assessed with an extended tolerance study and a minimization of the vignetting factor at the MICADO cold stop. The manuscript also contains a demonstration of the optical alignability of a 6M system in terms of pupil and focal plane steering that are essential to cope with the interface tolerances of the next generation of instrument at the foci of the extremely large telescopes.
MICADO will enable the ELT to perform diffraction limited near-infrared observations at first light. The instrument’s capabilities focus on imaging (including astrometric and high contrast) as well as single object spectroscopy. This contribution looks at how requirements from the observing modes have driven the instrument design and functionality. Using examples from specific science cases, and making use of the data simulation tool, an outline is presented of what we can expect the instrument to achieve.
MICADO is the Multi-AO Imaging Camera for Deep Observations, a first light instrument for the Extremely Large Telescope (ELT). It will provide the ELT with diffraction limited imaging capacity over a ~53-arcsec field of view, while operating with the Multi-Conjugate Adaptive Optics (MCAO) module MAORY (0.8-2.5 μm). Here, we present the design status of the MICADO derotator, which at the same time serves (i) as crucial mechanical interface between the cryo-opto-mechanical camera assembly and the instrument support structure and (ii) as high-precision image and wavefront sensor derotator to allow for 50 µas astrometry over the entire MCAO corrected field. Additionally, first test results are presented which were obtained with a derotator prototype based on a scaled 1:2 test bearing. The derotator test stand is essential to explore the limitations of the preferred bearing type in the context of the given requirements. The technical difficulties addressed by the design include: (i) design of adequate mechanical interfaces to minimize mass, deformation and the effect of the warping moment on the bearing and (ii) analysis of the friction-related stick-slip effects at low tracking velocities for the implementation of a suitable position-velocity closed-loop control system. Furthermore, our prototype setup is used to develop and test the required control concept of this high-precision application.
The paper describes the preliminary design of the MICADO calibration assembly. MICADO, the Multi-AO Imaging CAmera for Deep Observations, is targeted to be one of the first light instruments of the Extremely Large Telescope (ELT) and it will embrace imaging, spectroscopic and astrometric capabilities including their calibration. The astrometric requirements are particularly ambitious aiming for ~ 50 μas differential precision within and between single epochs. The MICADO Calibration Assembly (MCA) shall deliver flat-field, wavelength and astrometric calibration and it will support the instrument alignment to the Single-Conjugate Adaptive Optics wavefront sensor. After a complete overview of the MCA subsystems, their functionalities, design and status, we will concentrate on the ongoing prototype testing of the most challenging components. Particular emphasis is put on the development and test of the Warm Astrometric Mask (WAM) for the calibration of the optical distortions within MICADO and MAORY, the multiconjugate AO module.
The Multi-AO Imaging Camera for Deep Observations (MICADO) is one of the three first light instruments of the Extremely Large Telescope (ELT). Based on the Multi Conjugate Adaptive Optics (MCAO) modul MAORY MICADO offers diffraction-limited near-infrared imagery with a maximum field of view of 53 arcsec. In order to maintain diffraction-limited performance at the edge of the field, a precise image derotator is needed, which compensates the field rotation due to alt-azimuth mount of the telescope. In MICADO a four-point contact ball bearing is foreseen to rotate the cryostat for the compensation of the field rotation. Due to the heavy load and the high precision positioning of the ball bearing a control concept for the derotator is needed. The main challenge of positioning the ball bearing is the handling of friction effects. In this paper we present a control concept based on a velocity feedforward and a PID feedback control to rotate the bearing in the required position performance. At a scaled-down laboratory setup we demonstrate the position accuracy. To further improve the position accuracy we also study an additional friction compensation, which is based on a dynamical friction model.
MICADO will equip the E-ELT with a first light capability for diffraction limited imaging at near-infrared wavelengths. The instrument’s observing modes focus on various flavours of imaging, including astrometric, high contrast, and time resolved. There is also a single object spectroscopic mode optimised for wavelength coverage at moderately high resolution. This contribution provides an overview of the key functionality of the instrument, outlining the scientific rationale for its observing modes. The interface between MICADO and the adaptive optics system MAORY that feeds it is summarised. The design of the instrument is discussed, focusing on the optics and mechanisms inside the cryostat, together with a brief overview of the other key sub-systems.
The Multi-AO Imaging Camera for Deep Observations (MICADO), a first light instrument for the 39 m European Extremely Large Telescope (E-ELT), is being designed and optimized to work with the Multi-Conjugate Adaptive Optics (MCAO) module MAORY (0.8-2.5 μm). The current concept of the MICADO instrument consists of a structural cryostat (2.1 m diameter and 2 m height) with the wavefront sensor (WFS) on top. The cryostat is mounted via its central flange with a direct interface to a large 2.5-m-diameter high-precision bearing, which rotates the entire camera (plus wavefront sensor) assembly to allow for image derotation without individually moving optical elements. The whole assembly is suspended at 3.6 m above the E-ELT Nasmyth platform by a Hexapod-type support structure. We describe the design of the MICADO derotator, a key mechanism that must precisely rotate the cryostat/SCAO-WFS assembly around its optical axis with an angular positioning accuracy better than 10 arcsec, in order to compensate the field rotation due to the alt-azimuth mount of the E-ELT. Special attention is being given to simulate the performance of the derotator during the design phase, in which both static and dynamics behaviors are being considered in parallel. The statics flexure analysis is done using a detailed Finite Element Model (FEM), while the dynamics simulation is being developed with the mathematical model of the derotator implemented in Matlab/Simulink. Finally, both aspects must be combined through a realistic end-to-end model. The experiment designed to prove the current concept of the MICADO derotator is also presented in this work.
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