SOUL at LBT: commissioning results, science and future

The SOUL systems at the Large Bincoular Telescope can be seen such as precursor for the ELT SCAO systems, combining together key technologies such as EMCCD, Pyramid WFS and adaptive telescopes. After the first light of the first upgraded system on September 2018, going through COVID and technical stops, we now have all the 4 systems working on-sky. Here, we report about some key control improvements and the system performance characterized during the commissioning. The upgrade allows us to correct more modes (500) in the bright end and increases the sky coverage providing SR(K)>20% with reference stars G$_{RP}$<17, opening to extragalcatic targets with NGS systems. Finally, we review the first astrophysical results, looking forward to the next generation instruments (SHARK-NIR, SHARK-Vis and iLocater), to be fed by the SOUL AO correction.Comment: 13 pages, 10 figures, Adaptive Optics for Extremely Large Telescopes 7th Edition, 25-30 Jun 2023 Avignon (France

Optimizing Fourier-filtering WFS to reach sensitivity close to the fundamental limit

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Study of the LIFT focal-plane wavefront sensor for GALACSI NFM

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Sky coverage assessment for the European ELT: a joint evaluation for MAORY/MICADO and HARMONI

International audienceThe instruments developed for the upcoming Extremely Large Telescopes (ELTs) will need efficient Adaptive Optics (AO) systems to correct the effects of the atmospheric turbulence and allow imaging at the highest angular resolution. One of the most important requirement for ELT AO-assisted instruments will be to deliver diffractionlimited images in a significant part of the sky. For that, the instruments will be equipped with Laser Guide Stars (LGSs) providing most of the information required by AO instruments. But even with LGSs, AO systems still require the use of Natural Guide Stars (NGSs) to compensate for image motion (jitter) and some low order aberrations. These NGSs are eventually limiting the fraction of the sky that can be achieved by AO systems, the so-called Sky Coverage. In this paper, we first present the sky coverage assessment methods used for HARMONI (High Angular Resolution Monolithic Optical and Near-infrared Integral field spectrograph) and MAORY/MICADO (Multi-conjugate Adaptive Optics RelaY/Multi-AO Imaging Camera for Deep Observations), that are both instruments for the Extremely Large Telescope of the European Southern Observatory (ESO). They are based on a semi-analytical description of the main contributors in the AO error budget, allowing for a fast estimation of the residual jitter. As such, these methods are well suited for statistical estimation of the sky coverage on multiple science fields, and/or to efficiently explore the system parameter space. We then compute the sky coverage of the two instruments in cosmological fields from the Cosmic Assembly Near-IR Deep Extragalactic Legacy Survey (CANDELS) catalog. The goal is to provide an insight on the possibilities given by two different types of tomographic AO systems, i. e. Laser Tomography AO (LTAO) with HARMONI and Multi-Conjugate AO (MCAO) with MAORY, on the same telescope. In particular, we show that HARMONI and MAORY/MICADO are complementary, meaning that the overall sky coverage of ESO's ELT is much improved for applications common to both systems

Modélisation de la propagation du bruit dans la détection du front d'onde par filtrage de Fourier, limites fondamentales et comparaison quantitative

International audienceContext. Adaptive optics (AO) is a technique allowing for ground-based telescopes' angular resolution to be improved drastically. The wavefront sensor (WFS) is one of the key components of such systems, driving the fundamental performance limitations.Aims. In this paper, we focus on a specific class of WFS: the Fourier-filtering wavefront sensors (FFWFSs). This class is known for its extremely high sensitivity. However, a clear and comprehensive noise propagation model for any kind of FFWFS is lacking. Methods. Considering read-out noise and photon noise, we derived a simple and comprehensive model allowing us to understand how these noises propagate in the phase reconstruction in the linear framework.Results. This new noise propagation model works for any kind of FFWFS, and it allows one to revisit the fundamental sensitivity limit of these sensors. Furthermore, a new comparison between widely used FFWFSs is held. We focus on the two main FFWFS classes used: the Zernike WFS (ZWFS) and the pyramid WFS (PWFS), bringing new understanding of their behavior.Contexte: L'optique adaptative (OA) est une technique permettant d'améliorer de façon drastique la résolution angulaire des télescopes terrestres. L'analyseur de surface d'onde (WFS pour WaveFront Sensing en anglais) est l'un des composants clés de ces systèmes, ce qui entraîne des limitations de performance fondamentales.Objectifs: Dans cet article, nous nous concentrons sur une classe spécifique de de WFS : les capteurs de front d'onde à filtrage de Fourier (FFWFS). Cette classe est connue pour sa sensibilité extrêmement élevée. Cependant, un modèle clair et complet de propagation du bruit pour tout type de FFWFS fait défaut.Méthodes: En considérant le bruit de lecture et le bruit photonique, nous dérivons un modèle simple et complet permettant de comprendre comment ces bruits se propagent dans la reconstruction de phase dans le cadre linéaire.Résultats: Ce nouveau modèle de propagation du bruit fonctionne pour tout type de FFWFS, et permet de revisiter la limite de sensibilité fondamentale de ces capteurs. De plus, une nouvelle comparaison entre les FFWFS les plus utilisés est effectuée. Nous nous concentrons sur les deux principales classes de FFWFS utilisées : le Zernike WFS (ZWFS) et le pyramid WFS (PWFS), apportant une nouvelle compréhension de leur comportement

Modeling noise propagation in Fourier-filtering wavefront sensing, fundamental limits and quantitative comparison

Context. Adaptive optics (AO) is a technique allowing to drastically improve ground-based telescopes angular resolution. The wavefront sensor (WFS) is one of the key components of such systems, driving the fundamental performance limitations. Aims. In this paper, we focus on a specific class of WFS: the Fourier-filtering wavefront sensors (FFWFS). This class is known for its extremely high sensitivity. However, a clear and comprehensive noise propagation model for any kind of FFWFS is lacking. Methods. Considering read-out noise and photon noise, we derive a simple and comprehensive model allowing to understand how these noises propagates in the phase reconstruction in the linear framework. Results. This new noise propagation model works for any kind of FFWFS, and allows to revisit the fundamental sensitivity limit of these sensors. Furthermore, a new comparison between widely used FFWFS is held. We focus on the two main used FFWFS classes: the Zernike WFS (ZWFS) and the pyramid WFS (PWFS), bringing new understanding of their behavior

PSF nowcast using PASSATA simulations: towards a PSF forecast

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LGS tomography and spot truncation: tips and tricks

International audienceMAORY is the Laser Guide Star (LGS) assisted Multi Conjugated Adaptive Optics (MCAO) module of ESO's ELT where MAORY will provide a corrected field of view of 1 arcminute to its first client instrument MICADO. In the framework of the design phase B, the dimensioning of the LGS Shack-Hartmann Wave Front Sensor (WFS) has been investigated. On an ELT scale, the LGS spot truncation is severe and may lead to a potential loss of performance due to measurement noise as well as non-linearity and truncation induced bias. In this paper, we review the already known design options allowing to cope with LGS spot elongation and truncation problem. Then, we focus on MAORY and the design trade-off of a classical Shack-Hartmann WFS, addressing in particular the choice of the pixel scale and in turn the subaperture field of view. A larger field of view allows mitigating the truncation effects as long as the spot remains properly sampled, by means of extending it. Furthermore, we recall that in the case of a multi LGS WFS system, a large part of the problem can be solved thanks to the redundancy of pupil and metapupil sampling. The key lies in the proper tuning of the wavefront reconstruction, using as priors both the 3D turbulence covariance and well-tuned measurement noise and model errors. The number of reconstructed layers and the definition of their prior altitude and strength have been optimized. The WFS measurement errors are modelled by including the non-uniformity of LGS elongation across the pupil plane. The MCAO performance is evaluated both in terms of pure closed loop residuals and quasi static bias

Strategy for sensing petal mode in presence of AO residual turbulence with pyramid wavefront sensor

With the Extremely Large Telescope-generation telescopes come new challenges. The complexity of these telescopes' pupil creates new problems for Adaptive Optics. In particular, the large spiders necessary to support the massive optics of these telescopes create discontinuities in the wavefront measurement. These discontinuities appear as a new phase error dubbed the `petal mode'. This error is described as a differential piston between the fragment of the pupil separated by the spiders and is responsible for reducing the European Extremely Large Telescope's (ELT) resolution to a 15m telescope resolution. The aim of this paper is to study the measurement of the petal mode by adaptive optics sensors. We want to understand why the Pyramid Wavefront Sensor (PyWFS) cannot measure this petal mode under normal conditions and how to allow this measurement by adapting the Adaptive optics control scheme and the PyWFS. To facilitate our study, we consider a simplified version of the petal mode, featuring a simpler pupil than the ELT. We studied specifically how a system that separates the atmospheric turbulence from the petal measurement would behave. The unmodulated PyWFS (uPyWFS) but the uPyWFS does not make accurate measurements in the presence of atmospheric residuals. Studying the petal mode's power spectral density, we propose a filtering step, consisting of a pinhole around the pyramid tip. This reduces the first path residuals seen by the uPyWFS and restores its accuracy. Finally, we demonstrate our proposed system with end-to-end this http URL address the petal problem, a two-path adaptive optics with a sensor dedicated to the measurement of the petal mode seems necessary. Through this paper, we demonstrate that an uPyWFS can confuse the petal mode with the residuals from the first path. However, adding a spatial filter on top of said uPyWFS makes it a good petalometer candidate