Euclid Near Infrared Spectrometer and Photometer instrument concept and first test results obtained for different breadboards models at the end of phase C

The Euclid mission objective is to understand why the expansion of the Universe is accelerating through by mapping the geometry of the dark Universe by investigating the distance-redshift relationship and tracing the evolution of cosmic structures. The Euclid project is part of ESA's Cosmic Vision program with its launch planned for 2020 (ref [1]). The NISP (Near Infrared Spectrometer and Photometer) is one of the two Euclid instruments and is operating in the near-IR spectral region (900- 2000nm) as a photometer and spectrometer. The instrument is composed of: - a cold (135K) optomechanical subsystem consisting of a Silicon carbide structure, an optical assembly (corrector and camera lens), a filter wheel mechanism, a grism wheel mechanism, a calibration unit and a thermal control system - a detection subsystem based on a mosaic of 16 HAWAII2RG cooled to 95K with their front-end readout electronic cooled to 140K, integrated on a mechanical focal plane structure made with molybdenum and aluminum. The detection subsystem is mounted on the optomechanical subsystem structure - a warm electronic subsystem (280K) composed of a data processing / detector control unit and of an instrument control unit that interfaces with the spacecraft via a 1553 bus for command and control and via Spacewire links for science data This presentation describes the architecture of the instrument at the end of the phase C (Detailed Design Review), the expected performance, the technological key challenges and preliminary test results obtained for different NISP subsystem breadboards and for the NISP Structural and Thermal model (STM)

Les optiques adaptatives grand champ : stratégie de correction et validations expérimentales

Adaptive Optics (AO) allows to correct in real time the atmospheric perturbations thanks to the analysis of the turbulence with a WaveFront Sensor (WFS). The correction is then provided by a Deformable Mirror (DM). AO is however limited by two effects: anisoplanatism and sky coverage. To overcome these limitations, Wide Field AO (WFAO) concepts have been developed. These systems allow to probe the turbulent volume with several WFSs so as to perform a tomographic reconstruction of the turbulence. The correction is then applied in one specific direction of the Field of View (FoV) with one DM (Laser Tomography AO (LTAO)) or in a wide FoV thanks to several DMs (MultiConjugate AO (MCAO) or Multi-Object AO (MOAO)). The work performed during this PhD. is focused on the design of WFAO systems and experimental validations of these concepts. We especially study new issues related to wavefront sensing, correction and control laws. We have developed a bench called HOMER dedicated to experimental validation of WFAO concepts. The integration of the bench has allowed the study and the implementation of calibration procedures of the system, needed to obtain the best performance. These calibrations have been used in particular to implement a Linear Quadratic Gaussian (LQG) control. This control law is well adapted to WFAO since it provides an estimation and a prediction of the turbulent volume thanks to spatial and temporal a priori. Then the correction to be applied on the DMs is derived, in order to optimize the correction in a given FoV. We have implemented LQG control on HOMER for MCAO and LTAO configurations. This control leads to a significant gain in performance compared to a more standard approach based on a least-square reconstruction associated to an integrator control. This work corresponds to the first experimental results obtained with LQG control in WFAO and in closed-loop LTAO. It is also a first step towards the robustness study of LQG control with respect to model errors. In addition to these experimental results, we have also studied LGS related system design issues and have also reconsidered DM design rules in the perpective of the new VLT/ELT AO instruments.L'Optique Adaptative (OA) permet de corriger en temps-réel les perturbations engendrées par l'atmosphère grâce à l'analyse de la turbulence par un Analyseur de Surface d'Onde (ASO) puis une correction grâce à un Miroir Déformable (MD). L'OA est cependant soumise à deux limitations principales : l'anisoplanétisme et la couverture de ciel. Pour les pallier, les concepts d'OA dits grand champ ont été développés. Ces systèmes permettent de sonder le volume turbulent grâce à l'utilisation de plusieurs ASO pour réaliser une reconstruction tomographique de la turbulence. La correction peut ensuite être appliquée dans une direction spécifique du champ à l'aide d'un MD (système d'OA Tomographique Laser (LTAO)) ou dans un large champ grâce à plusieurs MD (système d'OA MultiConjuguée (MCAO) ou d'OA multi-objet (MOAO)). L'objectif des travaux menés au cours de cette thèse est d'étudier le dimensionnement des systèmes d'OA grand champ et la validation expérimentale de ces concepts en s'intéressant aux problématiques posées par la multi-analyse de surface d'onde, la correction et la commande. Pour cela, un banc de validation expérimentale en OA grand champ, appelé HOMER, a été développé. Son intégration a permis l'étude et la mise en place de procédures de calibration du système, nécessaires à l'obtention de très bonnes performances. Ces calibrations ont notamment été utilisées dans le cadre de l'implantation d'une commande optimale de type Linéaire Quadratique Gaussienne (LQG). Cette commande est particulièrement bien adaptée à l'OA grand champ puisqu'elle permet d'estimer et de prédire le volume turbulent grâce à des a priori spatiaux et temporels sur la turbulence, puis d'appliquer la correction sur les MD en optimisant la correction dans un champ donné. Cette commande, qui jusqu'à présent n'avait fait que l'objet d'une étude numérique en OA grand champ, a été mise en oeuvre sur HOMER pour des configurations de MCAO et de LTAO. Nous avons mis en évidence le gain apporté par cette commande comparée à une solution plus classique réalisant une reconstruction moindres carrés associée à un contrôleur intégrateur. Ces travaux constituent les premiers résultats expérimentaux obtenus grâce à l'implantation d'une commande LQG en OA grand champ ainsi qu'en LTAO boucle fermée. Nous avons ainsi débuté une étude de la robustesse de la commande LQG aux erreurs de modèles. Ces études expérimentales ont en outre été complétées par des études théoriques sur le dimensionnement de systèmes d'OA grand champ et le dimensionnement des MD pour répondre aux problématiques posées par ces nouveaux concepts d'OA

Phonetic and phonological variation in contemporary English: French comprehension of British & Irish regional varieties

International audienc

HARMONI at ELT: Full scale prototype of the laser guide star wavefront sensor

International audienceHARMONI is the first light visible and near-IR integral field spectrograph for the ELT. It covers a large spectral range from 450 nm to 2450 nm with resolving powers from 3500 to 18000 and spatial sampling from 60 mas to 4 mas. It can operate in two Adaptive Optics modes-SCAO (including a High Contrast capability) and LTAO-or with no AO mode. To prepare the final design reviews, we have built an optical bench to emulate and characterize the performance of the laser guide star (LGS) wavefront sensor (WFS) to be used in HARMONI. The WFS is a classic Shack-Hartmann, nonetheless pushed to the extreme due to the size of the primary mirror of the ELT (39 m). The WFS is composed of a 80 × 80 double side microlens array (MLA), an optical relay made of 6 lenses in order to re-image the light coming from the MLA on the detector, and a CMOS camera using a Sony detector with 1608 × 1104 pixels, RON< 3e, and a frame rate of 500Hz. The sensor has a large number of pixels to provide a field-of-view wider than 15 arcsec per subaperture over the full pupil, which is required to image the elongated LGS spots. An innovative feature of our bench is the use of a spatial light modulator (SLM) which allows us to emulate the M4 deformable mirror (DM) and the real position of its actuators, together with the projected spiders in the pupil plane. We report on the design and performance of our bench, including the first interaction matrices using the ELT-M4 influence functions and a non-elongated source. We expect to implement a system to emulate an elongated source in order to grasp a better understanding of its effects on wavefront sensing

HARMONI at ELT: Full scale prototype of the laser guide star wavefront sensor

International audienceHARMONI is the first light visible and near-IR integral field spectrograph for the ELT. It covers a large spectral range from 450 nm to 2450 nm with resolving powers from 3500 to 18000 and spatial sampling from 60 mas to 4 mas. It can operate in two Adaptive Optics modes-SCAO (including a High Contrast capability) and LTAO-or with no AO mode. To prepare the final design reviews, we have built an optical bench to emulate and characterize the performance of the laser guide star (LGS) wavefront sensor (WFS) to be used in HARMONI. The WFS is a classic Shack-Hartmann, nonetheless pushed to the extreme due to the size of the primary mirror of the ELT (39 m). The WFS is composed of a 80 × 80 double side microlens array (MLA), an optical relay made of 6 lenses in order to re-image the light coming from the MLA on the detector, and a CMOS camera using a Sony detector with 1608 × 1104 pixels, RON< 3e, and a frame rate of 500Hz. The sensor has a large number of pixels to provide a field-of-view wider than 15 arcsec per subaperture over the full pupil, which is required to image the elongated LGS spots. An innovative feature of our bench is the use of a spatial light modulator (SLM) which allows us to emulate the M4 deformable mirror (DM) and the real position of its actuators, together with the projected spiders in the pupil plane. We report on the design and performance of our bench, including the first interaction matrices using the ELT-M4 influence functions and a non-elongated source. We expect to implement a system to emulate an elongated source in order to grasp a better understanding of its effects on wavefront sensing

HARMONI at ELT: Full scale prototype of the laser guide star wavefront sensor

International audienceHARMONI is the first light visible and near-IR integral field spectrograph for the ELT. It covers a large spectral range from 450 nm to 2450 nm with resolving powers from 3500 to 18000 and spatial sampling from 60 mas to 4 mas. It can operate in two Adaptive Optics modes-SCAO (including a High Contrast capability) and LTAO-or with no AO mode. To prepare the final design reviews, we have built an optical bench to emulate and characterize the performance of the laser guide star (LGS) wavefront sensor (WFS) to be used in HARMONI. The WFS is a classic Shack-Hartmann, nonetheless pushed to the extreme due to the size of the primary mirror of the ELT (39 m). The WFS is composed of a 80 × 80 double side microlens array (MLA), an optical relay made of 6 lenses in order to re-image the light coming from the MLA on the detector, and a CMOS camera using a Sony detector with 1608 × 1104 pixels, RON< 3e, and a frame rate of 500Hz. The sensor has a large number of pixels to provide a field-of-view wider than 15 arcsec per subaperture over the full pupil, which is required to image the elongated LGS spots. An innovative feature of our bench is the use of a spatial light modulator (SLM) which allows us to emulate the M4 deformable mirror (DM) and the real position of its actuators, together with the projected spiders in the pupil plane. We report on the design and performance of our bench, including the first interaction matrices using the ELT-M4 influence functions and a non-elongated source. We expect to implement a system to emulate an elongated source in order to grasp a better understanding of its effects on wavefront sensing

Linear Quadratic Gaussian Control Applied to WFAO Systems: Simulation and Experimental Results

International audienc

HARMONI at ELT: Full scale prototype of the laser guide star wavefront sensor

International audienceHARMONI is the first light visible and near-IR integral field spectrograph for the ELT. It covers a large spectral range from 450 nm to 2450 nm with resolving powers from 3500 to 18000 and spatial sampling from 60 mas to 4 mas. It can operate in two Adaptive Optics modes-SCAO (including a High Contrast capability) and LTAO-or with no AO mode. To prepare the final design reviews, we have built an optical bench to emulate and characterize the performance of the laser guide star (LGS) wavefront sensor (WFS) to be used in HARMONI. The WFS is a classic Shack-Hartmann, nonetheless pushed to the extreme due to the size of the primary mirror of the ELT (39 m). The WFS is composed of a 80 × 80 double side microlens array (MLA), an optical relay made of 6 lenses in order to re-image the light coming from the MLA on the detector, and a CMOS camera using a Sony detector with 1608 × 1104 pixels, RON< 3e, and a frame rate of 500Hz. The sensor has a large number of pixels to provide a field-of-view wider than 15 arcsec per subaperture over the full pupil, which is required to image the elongated LGS spots. An innovative feature of our bench is the use of a spatial light modulator (SLM) which allows us to emulate the M4 deformable mirror (DM) and the real position of its actuators, together with the projected spiders in the pupil plane. We report on the design and performance of our bench, including the first interaction matrices using the ELT-M4 influence functions and a non-elongated source. We expect to implement a system to emulate an elongated source in order to grasp a better understanding of its effects on wavefront sensing