The SAXO+ upgrade of the VLT/SPHERE adaptive optics system introduces a second-stage near-infrared pyramid wavefront sensor to improve high-contrast imaging, making accurate calibration of non-common path aberrations (NCPAs) essential to fully exploit its performance. This work refines the expected level of NCPAs in SAXO+ and presents the calibration procedures developed for static NCPA compensation and focal-plane dark-hole control. Monte Carlo simulations based on an updated Zemax optical model were used to estimate the NCPA error budget. These simulations are in good agreement with previous measurements on SPHERE and with the assumptions adopted in earlier performance studies. We also propose a calibration strategy that offloads most static aberration correction to the first-stage deformable mirror while preserving the second-stage mirror stroke for high-speed adaptive optics correction. These results validate the expected SAXO+ optical quality and establish the calibration framework required for efficient NCPA compensation and focal-plane wavefront control during future on-sky operations.

MICADO is the designated ELT first light instrument, a near-infrared imager working at the diffraction limit of the telescope thanks to a SCAO and an MCAO mode. Since summer 2024, MICADO is in its AIT phase and all MICADO partners are currently integrating their subsystems. The MICADO SCAO module will follow three successive AIT phases in France: the beta flat configuration, the flat configuration and the final configuration. In this contribution I will first present the progress made in the AIT of the beta flat configuration and its closed loop results. I will then present the performed and on-going tasks for the flat and final configurations (manufacturing, delivery and integration of several SCAO subsystems and pieces of software) and the results obtained so far in the flat configuration. I will then conclude with the expected following steps of the SCAO module AIT in Garching.

Performing ferromagnetic resonance (FMR) experiments on a polycrystalline FeRh (270 nm)/Ta (100 nm)/GaAs film, we evidence a low-field hysteretic signal, in addition to the usual nonhysteretic FMR absorption peaks. Its coercivity coincides with the static coercivity of the sample, which can be strongly tuned with temperature, thanks to the first-order nature of the antiferromagnetic to ferromagnetic transition of FeRh. The sample was made using a graded composition technique which allows us to obtain the Fe/Rh stoechiometry required for the presence of an antiferromagnetic-ferromagnetic transition. We show that the low-field microwave absorption (LFMA) signal can be well modeled by simply introducing the hysteresis of the static magnetization in the dynamic magnetic susceptibility. Finally, previous observations of LFMA on a cobalt thin film are also reproduced by this model.

In order to address new science objectives in exoplanet imaging, the SAXO+ technical development project has been undertaken for the SPHERE instrument at ESO's VLT. As a part of this, the AO system will be completed by adding a second, faster stage of correction. We present simulation results obtained by implementing an optimal predictive linear quadratic Gaussian controller for the 2nd stage. The prediction relies on a stochastic state-space disturbance model fully identified from closed-loop measurements. In addition, we also investigate a disentangled cascade AO (dCAO) mode where the model represents the full incoming disturbance and is identified using in addition the 1st stage commands.

SAXO+ is a second-stage adaptive optics module for the SPHERE instrument at VLT. It has been proposed to increase the achievable contrast and improve the current performance of detecting and characterizing exoplanets and disks. It is developed by the SPHERE+ consortium as part of the roadmap activity for the planet finder instrument (PCS) of the Extremely Large Telescope (ELT). This paper describes the optical and mechanical design of SAXO+.

SPHERE, operating at the VLT since 2014, is currently one of the high-contrast instruments with a higher performance. Its adaptive optics system, known as SAXO, will be upgraded to SAXO+, which features the addition of a second stage of adaptive optics. This stage will use a near-infrared pyramid wavefront sensor to record images of fainter exoplanets around redder stars. In this work, we compare the performance of SAXO and SAXO+. We look for the optimal values of the key system parameters of SAXO+ for various science cases and turbulence conditions. We performed numerical simulations using COMPASS, an end-to-end adaptive optics simulation tool. We simulated perfect coronagraph images of an on-axis point source, and we minimized the residual starlight intensity between 3 and $5\ / D$ as a performance criterion. The explored parameter space includes science cases (described by magnitude in G and J bands), turbulence conditions (seeing and coherence time), and key system parameters (first and second stage gains, first and second stage frequencies, pyramid modulation radius, pyramid modal gains optimization). In every science case and turbulence condition, SAXO+ reduces the residual starlight intensity inside the correction zone of the second stage by a factor of ten compared to SAXO. The optimal first stage gain is lower for SAXO+ than for SAXO alone. We quantified the gain in performance of SAXO+ when changing the second stage frequency from 2\,kHz to 3\,kHz, and we conclude that 2\,kHz may be sufficient for most realistic conditions. We give the optimal first stage gain as well as the first and second stage frequencies for every seeing, coherence time, and science case. Finally, we find that a $2\ WFS / D$ pyramid modulation radius is a good trade-off between performance and robustness against varying turbulence conditions. This study shows that the future SAXO+ system will outperform the current SAXO system in all studied cases.

MICADO is the ELT first light instrument, an imager working at the diffraction limit of the telescope thanks to two adaptive optics (AO) modes: a single conjugate one (SCAO), available at the instrument first light and developed by the MICADO consortium, and a multi conjugate one (MCAO), developed by the MORFEO consortium. Although the project final design review process is about to be completed, the review board and ESO acknowledged that "the review of the final design can be considered complete for the majority of the MICADO sub-systems" and agreed that MICADO can start manufacturing. For the MICADO SCAO module, we have started the manufacturing of several parts: the majority of the SCAO optics and of the SCAO mechanics, the real-time computer software and the instrument control software. This manufacturing is ordered in several steps to allow the progressive integration of a first full AO close loop with the final SCAO parts. In this contribution, we will focus on the first two steps: on our AO Sesame bench and the so-called "beta flat configuration". We will present the status of this manufacturing and the first results obtained.

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-VLT) and the next generation Extremely Large Telescopes (e.g. ESO-ELT). Finally, the 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.

This study introduces a novel frequency-based data-driven controller for adaptive optics, using power spectral density for optimization while ensuring stability criteria. It addresses disturbance rejection, command amplitude constraints and system transfer functions through convex optimization to obtain an optimal control in an infinite input response filter form. Evaluated within the SAXO+ project, it demonstrates efficacy under diverse atmospheric conditions and operational scenarios. The proposed controller is tested in both standard and disentangled adaptive optics schemes, showcasing its adaptability and performance. Experimental validation is conducted using the COMPASS simulation tool, affirming the controller's promise for enhancing adaptive optics systems in real-world applications.

SAXO+ is a planned enhancement of the existing SAXO, the VLT/ SPHERE adaptive optics system, deployed on ESO's Very Large Telescope. This upgrade is designed to significantly enhance the instrument's capacity to detect and analyze young Jupiter-like planets. The pivotal addition in SAXO+ is a second-stage adaptive optics system featuring a dedicated near-infrared pyramid wavefront sensor and a second deformable mirror. This secondary stage is strategically integrated to address any residual wavefront errors persisting after the initial correction performed by the current primary AO loop, SAXO. However, several recent studies clearly showed that in good conditions, even in the current system SAXO, non-common path aberrations (NCPAs) are the limiting factor of the final normalized intensity in focal plane, which is the final metric for ground-based high-contrast instruments. This is likely to be even more so the case with the new AO system, with which the AO residuals will be minimized. Several techniques have already been extensively tested on SPHERE in internal source and/or on-sky and will be presented in this paper. However, the use of a new type of sensor for the second stage, a pyramid wavefront sensor, will likely complicate the correction of these aberrations. Using an end-to-end AO simulation tool, we conducted simulations to gauge the effect of measured SPHERE NCPAs in the coronagraphic image on the second loop system and their correction using focal plane wavefront sensing systems. We finally analyzed how the chosen position of SAXO+ in the beam will impact the evolution of the NCPAs in the new instrument.

MICADO SCAO RTC hard real-time capabilities are provided by COSMIC, while the soft real-time features rely on the ESO RTC Toolkit. The RTC has actively begun the MAIT phase. For this purpose, a full-scale setup has been assembled to start the integration of the S-RTC and H-RTC. The setup is used with an additional simulation node running either COMPASS or ESO WFS simulator, allowing to validate the various implementations of the RTC in terms of AO performance and latency requirements. On top of that, an instance of the RTC has been deployed on the SESAME bench at LESIA. This paper will present the MICADO SCAO RTC architecture after final design review, the design choices and the current status of the MAIT activities related to the RTC. It will provide an overview of the H-RTC pipeline design, including performance benchmark and validation through simulation mode and on-bench results. It will also picture the current status of the RTC Toolkit integration activities for the S-RTC on multi-nodes cluster including the first implementation of telemetry consumption, data tasks, data storage, data visualization, H-RTC optimization and automation mechanisms.

SAXO+ is the upgrade of SAXO, the adaptive optics system used by the SPHERE instrument on ESO's Very Large Telescope. SAXO+ consists of a second stage adaptive optics downstream of the first stage, SAXO, to improve wavefront correction, achieve deeper contrast in the coronagraphic images and observe fainter and redder stars. Using the COMPASS end-to-end simulation tool, we assess the SAXO+ improved correction compared to SAXO in multiple science cases and turbulence conditions. The adaptive optics performance criterion is the starlight residual intensity in the coronagraph image : the lower the better. We show that SAXO+ improves the performance of the adaptive optics system by a factor of 10 in all simulated observing conditions. We specifically study the impact of the second stage frequenc and we conclude that a 2 kHz second stage is a reasonable trade-off between performance and technical constraints on the real-time system.