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High contrast imaging and high-resolution spectroscopy are powerful techniques to characterize multi-component astronomical systems, examples of which range from stars with planetary companions to similar-mass stellar binaries. The first part of this thesis concerns the instrumentation and science behind detecting substellar companions. We present the development of single photon-counting detectors known as Microwave Kinetic Inductance Detectors (MKIDs) for exoplanet direct imaging. Optical/Near-IR MKIDs are low noise detectors which can resolve both the energy and arrival time of individual photons, returning microsecond-accurate time-tagged photon lists. These lists allow for image processing techniques that take advantage of photon spectral and arrival time information to model and subtract the stellar background, leaving behind signal from the faint planetary companion. We discuss the commissioning and characterization of the MKID Exoplanet Camera (MEC), a 20,440 pixel MKID infrared camera that interfaces with the The Subaru Coronagraphic Extreme Adaptive Optics (SCExAO) planet finding instrument on the Subaru Telescope at Mauna Kea. MEC is the first permanently deployed near-infrared MKID instrument and is designed to operate both as an IFU, and as a focal plane wavefront sensor in a multi-kHz feedback loop with SCExAO. We present the development and construction of a second generation digital readout system for MEC. Our readout system is capable of identifying, analyzing, and recording photon detection events in real time with a time resolution of order a few microseconds.The second part of this thesis addresses the characterization of the orbital properties and stellar components of multiple star systems through high-resolution spectroscopy. We analyze stellar binaries observed with the Michigan/Magellan Fiber System (M2FS), a fiber-fed double spectrograph that was used to complete a several year-long survey of the core half-degree of open clusters NGC 2516 and NGC 2422. This survey targeted all stars identified as solar-analog photometric members. We present orbits for 24 binaries in the field of NGC 2516 (300 Myr) and 13 binaries in the field of NGC 2422 (130 Myr). Six of these systems are double-lined spectroscopic binaries (SB2s). We fit these RV variable systems with orvara, a MCMC-based fitting program that models Keplerian orbits. We use precise stellar parallaxes and proper motions from Gaia EDR3 to determine cluster membership. We impose a barycentric radial velocity prior on all cluster members; this significantly improves our orbital constraints.Two of our systems have periods between 5 and 15 days, the critical window in which tides efficiently damp orbital eccentricity. These binaries should be included in future analyses of circularization across similarly-aged clusters. We also find a relatively flat distribution of binary mass ratios, consistent with previous work. We identify a field star whose secondary has a mass in the brown dwarf range, as well as two cluster members whose RVs suggest the presence of an additional companion. Our orbital fits will help constrain the binary fraction and binary properties across stellar age and across stellar environmentThis thesis explores the detection and characterization of stellar companions at opposite ends of the companion mass range: planetary and stellar. We present technological advances ranging across the fields of instrumentation, image processing (both real-time and post-processing), and stellar system characterization.

Developing dual-state luminophores (DSLs) with strong fluorescence in both the monomer and aggregate states is urgently needed but remains a huge challenge because most current luminophores are eit...

Astronomy is the ultimate observational science. Objects outside our solar system are beyond our reach, so we are limited to acquiring knowledge at a distance. This motivates the need to advance astrophysical imaging technologies, particularly for the field of high contrast imaging, where some of the most highly prized science goals require high fidelity imagery of exoplanets and of the circumstellar structures associated with stellar and planetary birth. Such technical capabilities address questions of both the birth and death of stars which in turn informs the grand recycling of matter in the chemical evolution of the galaxy and universe itself. Ground-based astronomical observation primarily relies on extreme adaptive optics systems in order to extract signals arising from faint structures within the immediate vicinity of luminous host stars. These systems are distinguished from standard adaptive optics systems in performing faster and more precise wavefront correction which leads to better imaging performance. The overall theme of this thesis therefore ties together advanced topics in artificial intelligence with techniques and technologies required for the field of high contrast imaging. This is accomplished with demonstrations of deep learning methods used to improve the performance of extreme adaptive optics systems and is deployed and benchmarked with data obtained at the Subaru Coronagraphic Extreme Adaptive Optics (SCExAO) system operating at the observatory on the summit of Mauna Kea in Hawaii. Solutions encompass both hardware and software, with optimal recovery of scientific outcomes delivered by model fitting of high contrast imaging data with modern machine learning techniques. This broad-ranging study subjecting acquisition, analysis and modelling of data hopes to yield more accurate and higher fidelity observables which in turn delivers improved interpretation and scientific delivery.

This thesis focuses around using the Gemini Planet Imager (GPI), an instrument designed to directly-image exoplanets, as part of the GPI Exoplanet Survey (GPIES), a multi-year survey to image and characterize Jovian exoplanets orbiting at Solar System Scales (5-100~au). The first half of this thesis is on building the data analysis infrastructure for GPIES. I helped commission GPI by characterizing the ability to measure the position and flux of a star when it is placed behind an occulting mask specifically designed to suppress starlight. I also led the development of the automated data processing infrastructure for GPIES that handles all of the data storage, indexing, and processing. This data infrastructure has optimized survey execution, ensured uniform data products, and characterized instrument performance. In the second half of this thesis, I characterize two notable exoplanetary systems through precise astrometry and orbital analysis. I present improvements to astrometric data analysis that allow us to measure the position of $\beta$ Pic b to one milliarcsecond, the most precise astrometry of an exoplanet to date. I tighten constraints on its orbit, including timing a window in which circumplanetary material of this young exoplanet could be transiting the star. Lastly, I apply the same astrometry techniques to the HR 8799 system which harbors four Jovian exoplanets. I added dynamical stability priors on my orbit fits using an N-body integrator to find stable orbits in the system. Through this, I explore possible orbital resonances and place dynamical constraints on the masses of the planets.

International audience; We present the results obtained with an end-to-end simulator of an Extreme Adaptive Optics (XAO) system control loop. It is used to predict its on-sky performances and to optimise the AO loop algorithms. It was first used to validate a novel analytical model of the fitting error, a limit due to the Deformable Mirror (DM) shape. Standard analytical models assume a sharp correction under the DM cutoff frequency, disregarding the transition between the AO corrected and turbulence dominated domains. Our model account for the influence function shape in this smooth transition. Then, it is well-known that Shack-Hartmann wavefront sensors (SH-WFS) have a limited spatial bandwidth, the high frequencies of the wavefront being seen as low frequencies. We show that this aliasing error can be partially compensated (both in terms of Strehl ratio and contrast) by adding priors on the turbulence statistics in the framework of an inverse problem approach. This represents an alternative to the standard additional optical filter used in XAO systems. In parallel to this numerical work, a bench was aligned to experimentally test the AO system and these new algorithms comprising a DM192 ALPAO deformable mirror and a 15x15 SH-WFS. We present the predicted performances of the AO loop based on end-to-end simulations.

SPHERE+ is a proposed upgrade of the SPHERE instrument at the VLT, which is intended to boost the current performances of detection and characterization for exoplanets and disks. SPHERE+ will also serve as a demonstrator for the future planet finder (PCS) of the European ELT. The main science drivers for SPHERE+ are 1/ to access the bulk of the young giant planet population down to the snow line ($3-10$ au), to bridge the gap with complementary techniques (radial velocity, astrometry); 2/ to observe fainter and redder targets in the youngest ($1-10$\,Myr) associations compared to those observed with SPHERE to directly study the formation of giant planets in their birth environment; 3/ to improve the level of characterization of exoplanetary atmospheres by increasing the spectral resolution in order to break degeneracies in giant planet atmosphere models. Achieving these objectives requires to increase the bandwidth of the xAO system (from $\sim$1 to 3\,kHz) as well as the sensitivity in the infrared (2 to 3\,mag). These features will be brought by a second stage AO system optimized in the infrared with a pyramid wavefront sensor. As a new science instrument, a medium resolution integral field spectrograph will provide a spectral resolution from 1000 to 5000 in the J and H bands. This paper gives an overview of the science drivers, requirements and key instrumental trade-off that were done for SPHERE+ to reach the final selected baseline concept., To appear in the Proceedings of the SPIE Astronomical Telescopes + Instrumentation (2022), 13 pages, 6 figure

Hi-5 is the L'-band (3.5-4.0 $\mu$m) high-contrast imager of Asgard, an instrument suite in preparation for the visitor focus of the VLTI. The system is optimized for high-contrast and high-sensitivity imaging within the diffraction limit of a single UT/AT telescope. It is designed as a double-Bracewell nulling instrument producing spectrally-dispersed (R=20, 400, or 2000) complementary nulling outputs and simultaneous photometric outputs for self-calibration purposes. In this paper, we present an update of the project with a particular focus on the overall architecture, opto-mechanical design of the warm and cold optics, injection system, and development of the photonic beam combiner. The key science projects are to survey (i) nearby young planetary systems near the snow line, where most giant planets are expected to be formed, and (ii) nearby main sequence stars near the habitable zone where exozodiacal dust that may hinder the detection of Earth-like planets. We present an update of the expected instrumental performance based on full end-to-end simulations using the new GRAVITY+ specifications of the VLTI and the latest planet formation models., Comment: 16 pages, 9 figures, SPIE 2022 "Astronomical Telescopes and Instrumentation" manuscript 12183-16

Here we present an optical system composed of two mirrors such that at the input/output, the light is a plane wave but with a user-defined apodization factor. The model presented is an analytic closed form with no numerical approximations or iterations. We test the model with illustrative scenarios, and the results are as expected; the system is stigmatic with the desired apodization factor. Thus, this system has several potential applications in high contrast imaging.

The compelling scientific rewards for exoplanet detection in astronomy necessitates the development of imaging techniques able to explore parts of the parameter space unreachable by indirect methods: isolating planetary light for further investigation. Nulling interferometry is one of the most promising technologies for imaging exoplanets within stellar habitable zones. The Guided-Light Interferometric Nulling Technology (GLINT) instrument, the first multi-baseline photonic nulling interferometer, has explored the potential for photonics to deliver the performance to reach the realms of contrast and separation required for exoplanet detection in the near-infrared. GLINT highlights two key issues that limit current-generation photonic nullers: residual phase variations and chromaticity within the beam combiner. Both limitations are addressed by the use of tricouplers, which can deliver a broadband, achromatic null together with phase measurements for fringe tracking. This thesis gives a derivation of the interactions of the tricoupler as the nuller’s core element, and presents designs for two devices to cancel on-axis light achromatically. A fully symmetric tricoupler is introduced, allowing a null signal to be delivered together with baseline-phase-dependent splitting into a pair of bright channels. Within some design trade space, the science signal or the fringe tracking ability can be prioritised. A phase shifter is also presented here, which can induce a phase shift of 180° with a variation of 0.6° in the 1.4-1.7μm band, producing a near-achromatic differential phase between beams. This functionality is required for optimal operation of the tricoupler nulling stage. Both devices can be integrated and replicated on a single photonic chip using ultrafast laser inscription, and can deliver a deep, broadband null together with a real-time fringe phase metrology signal.

We present a high-contrast imaging search for Pa$\beta$ line emission from protoplanets in the PDS~70 system with Keck/OSIRIS integral field spectroscopy. We applied the high-resolution spectral differential imaging technique to the OSIRIS $J$-band data but did not detect the Pa$\beta$ line at the level predicted using the parameters of \cite{Hashimoto2020}. This lack of Pa$\beta$ emission suggests the MUSE-based study may have overestimated the line width of H$\alpha$. We compared our Pa$\beta$ detection limits with the previous H$\alpha$ flux and H$\beta$ limits and estimated $A_{\rm V}$ to be $\sim0.9$ and 2.0 for PDS~70~b and c respectively. In particular, PDS~70~b's $A_{\rm V}$ is much smaller than implied by high-contrast near-infrared studies, which suggests the infrared-continuum photosphere and the hydrogen-emitting regions exist at different heights above the forming planet., Comment: 8pages, 5 figs, accepted for publication in AJ

International audience; The Giant Segmented Mirror Telescopes (GSMTs) including the Giant Magellan Telescope (GMT), the Thirty Meter Telescope (TMT), and the European Extremely Large Telescope (E-ELT), all have extreme adaptive optics (ExAO) instruments planned that will use pyramid wavefront sensors (PWFS). The ExAO instruments all have common features: a high-actuator-count deformable mirror running at extreme speeds (>1 kHz); a high-performance wavefront sensor (WFS); and a high-contrast coronagraph. ExAO WFS performance is currently limited by the need for high spatial sampling of the wavefront which requires large detectors. For ExAO instruments for the next generation of telescopes, alternative architectures of WFS are under consideration because there is a trade-off between detector size, speed, and noise that reduces the performance of GSMT-ExAO wavefront control. One option under consideration for a GSMT-ExAO wavefront sensor is a three-sided PWFS (3PWFS). The 3PWFS creates three copies of the telescope pupil for wavefront sensing, compared to the conventional four-sided PWFS (4PWFS), which uses four pupils. The 3PWFS uses fewer detector pixels than the 4PWFS and should therefore be less sensitive to read noise. Here we develop a mathematical formalism based on the diffraction theory description of the Foucault knife-edge test that predicts the intensity pattern after the PWFS. Our formalism allows us to calculate the intensity in the pupil images formed by the PWFS in the presence of phase errors corresponding to arbitrary Fourier modes. We use these results to motivate how we process signals from a 3PWFS. We compare the raw intensity (RI) method, and derive the Slopes Maps (SM) calculation for the 3PWFS, which combines the three pupil images of the 3PWFS to obtain the X and Y slopes of the wavefront. We then use the Object Oriented MATLAB Adaptive Optics toolbox (OOMAO) to simulate an end-to-end model of an AO system using a PWFS with modulation and compare the performance of the 3PWFS to the 4PWFS. In the case of a low read noise detector, the Strehl ratios of the 3PWFS and 4PWFS are within 0.01. When we included higher read noise in the simulation, we found a Strehl ratio gain of 0.036 for the 3PWFS using RI over the 4PWFS using SM at a stellar magnitude of 10. At the same magnitude, the 4PWFS RI also outperformed the 4PWFS SM, but the gain was only 0.012 Strehl. This is significant because 4PWFS using SM is how the PWFS is conventionally used for AO wavefront sensing. We have found that the 3PWFS is a viable WFS that can fully reconstruct a wavefront and produce a stable closed-loop with correction comparable to that of a 4PWFS, with modestly better performance for high read-noise detectors.

Snellen, I.A.G. et al., In this White Paper, which was submitted in response to the European Space Agency (ESA) Voyage 2050 Call, we recommend the ESA plays a proactive role in developing a global collaborative effort to construct a large high-contrast imaging space telescope, e.g. as currently under study by NASA. Such a mission will be needed to characterize a sizable sample of temperate Earth-like planets in the habitable zones of nearby Sun-like stars and to search for extraterrestrial biological activity. We provide an overview of relevant European expertise, and advocate ESA to start a technology development program towards detecting life outside the Solar System., I.S. acknowledges funding from the European Research Council (ERC) under the European Union’s Horizon 2020 research and innovation program under grant agreement No 694513. A.L.M. acknowledges the financial support of the F.R.S.-FNRS through a postdoctoral researcher grant. MB acknowledges support from the UK Science and Technology Facilities Council (STFC) research grant ST/S000631/1. I.R. acknowledges support from the Spanish Ministry of Science and Innovation and the European Regional Development Fund through grant PGC2018-098153-B-C33, as well as the support of the Generalitat de Catalunya/CERCA programme. E.P. acknowledges support from the Spanish Ministry of Science through grant PGC2018-098153-B-C31. J.M.D. acknowledges funding from the European Research Council (ERC) under the European Unions Horizon 2020 research and innovation programme (grant agreement no. 679633; Exo-Atmos) Part of this research was carried out at the Jet Propulsion Laboratory, California Institute of Technology, under a contract with the National Aeronautics and Space Administration. We acknowledge financial support from the ASI-INAF agreement n.2018-16-HH.0 We acknowledge financial support from Spanish MCIU SEV-2017-0709 and PID2019-110689RB-I00 awards. We acknowledge financial support from the ASI-INAF agreement n.2018-16-HH.0 AV acknowledges funding from the European Research Council (ERC) under the European Union’s Horizon 2020 research and innovation programme (grant agreement No. 757561). KH acknowledges funding from the European Research Council (ERC) under the European Union’s Horizon 2020 research and innovation programme (grant agreement No. 771620). NJM acknowledges funding from the Leverhulme Trust, and a Science and Technology Facilities Council Consolidated Grant (ST/R000395/1). PdV acknowledges funding from the Netherlands Organisation for Scientific Research NWO (Veni Grant No. 639.041.750). IP acknowledges financial support from the ASI-INAF agreements 2019-29-HH.06-HH.0 and 2015-019-R.1-2018. FS acknowledges funding from the European Research Council (ERC) under the European Union’s Horizon 2020 research and innovation programme (grant agreement no. 678194; FALCONER). MJ acknowledges support from the Knut and Alice Wallenberg foundation (KAW). JLB acknowledges funding from the European Research Council (ERC) under the European Union’s Horizon 2020 research and innovation program under grant agreement No 805445. T.H. acknowledges support from the European Research Council under the Horizon 2020 Framework Program via the ERC Advanced Grant Origins 83 24 28. JLG acknowledges ISSI Team 464 for useful discussion.

Techniques and Instrumentation for Detection of Exoplanets X (2021) San Diego1 August 2021 through 5 August 2021, Code 172620.--Proceedings of SPIE - The International Society for Optical Engineering vol. 118232021 Article number 118230H, The James Webb Space Telescope (JWST) and its suite of instruments will offer significant capabilities towards the high contrast imaging of objects such as exoplanets, protoplanetary disks, and debris disks at short angular separations from their considerably brighter host stars. For the JWST user community to simulate and predict these capabilities for a given science case, the JWST Exposure Time Calculator (ETC) is the most readily available and widely used simulation tool. However, the ETC is not capable of simulating a range of observational features that can significantly impact the performance of JWST's high contrast imaging modes (e.g.Target acquisition offsets, temporal wavefront drifts, small grid dithers, and telescope rolls) and therefore does not produce realistic contrast curves. Despite the development of a range of more advanced software that includes some or all of these features, these instead lack in either a) instrument diversity, or b) accessibility for novice users, This project was supported by a grant from STScI (JWST-ERS-01386) under NASA contract NAS5-03127, With funding from the Spanish government through the Severo Ochoa Centre of Excellence accreditation SEV-2017-0709

Following the success of the Decadal Survey Testbed (DST), the HCIT team at JPL has developed a companion testbed, the Decadal Survey Testbed 2 (DST2), that further implements lessons learned from DST and from recent modeling work at JPL in support of the HabEx concept. Commissioning for DST2 is currently targeted for Fall 2021. Here we report on the detailed design of DST2 and status of integration and testing highlighting comparisons/changes from the original DST. Expected performance is summarized here, with details of the modeling effort provided in Noyes et al. also in these proceedings.

Current and future high-contrast imaging instruments require extreme adaptive optics systems to reach contrasts necessary to directly imaged exoplanets. Telescope vibrations and the temporal error induced by the latency of the control loop limit the performance of these systems. One way to reduce these effects is to use predictive control. We describe how model-free reinforcement learning can be used to optimize a recurrent neural network controller for closed-loop predictive control. First, we verify our proposed approach for tip–tilt control in simulations and a lab setup. The results show that this algorithm can effectively learn to mitigate vibrations and reduce the residuals for power-law input turbulence as compared to an optimal gain integrator. We also show that the controller can learn to minimize random vibrations without requiring online updating of the control law. Next, we show in simulations that our algorithm can also be applied to the control of a high-order deformable mirror. We demonstrate that our controller can provide two orders of magnitude improvement in contrast at small separations under stationary turbulence. Furthermore, we show more than an order of magnitude improvement in contrast for different wind velocities and directions without requiring online updating of the control law.

In situexperimental studies have been key in uncovering the often elusive pathways of nucleation and crystal growth. In the field of material science and medicine this offers the prospect of controlling crystallization processes to fight disease or tailor materials towards specific applications. To further advance this quest there is a need for flexible techniques mapping the different stages of crystallization with maximal sensitivity. This article reviews the benefits of nonlinear optical techniques to take on this challenge. We provide a perspective on various nucleation and crystal growth studies that were carried out by nonlinear optical probing techniques. A theoretical background is established, different relevant nonlinear optical phenomena are defined, and optical setups that have been used by various authors are summarized. A primary focus is demonstrating the benefits of nonlinear optical techniques for thein situstudy of crystallization. These benefits include low detection limits, complementary information by combining second- and third-order techniques, as well as relatively simple bench-top setups. Through microscopy, high contrast imaging of concomitant formations can moreover be achieved. The discussion outlines several studies involving ionic compounds, noble metal nanoparticles, polymers, metal organic frameworks and pharmaceutical compounds. Finally, we discuss future evolutions in nonlinear optical probing that are expected to further advance the field.

International audience; The Center for Optics and Photonics of the National Astronomical Research Institute of Thailand, together with the Institut d'Optique Graduate School and the Centre de Recherche Astrohpysique de Lyon (CRAL), is currently developing the Evanescent Wave Coronagraph (EvWaCo). The coronagraph relies on the tunneling effect to produce a fully achromatic focal plane mask (FPM) with an adjustable size. The full instrument comprises a coronagraph and adaptive optics system that will be mounted on the Thai National Telescope and is specified to reach a raw contrast of 10−4 at an inner working angle of 3 Airy radii. The coronagraph will be used to perform high contrast observations of stellar systems during on-sky observations over the spectral domain [600 nm, 900 nm]. In this paper, we present the opto-mechanical design of the EvWaCo prototype and the performance measured in laboratory conditions. We also discuss the potential applications for space-based observations and the development plan under this project in the next five years.

NASA is developing starshade technology to Technology Readiness Level 5 within a directed activity called S5. The objective of S5 is to mature starshade technology to the level that exoplanet imaging missions, such as Starshade Rendezvous and HabEx, can begin the formulation phase. This paper outlines the S5 activity as a whole, to show how it closes all starshade technology gaps in a mutually consistent way. It serves as a companion paper to several other papers in this special section that report progress in specific starshade technologies.

Starshade concepts must be stowed within rocket fairings for launch and then deployed in space. The in-plane deployment accuracy must be on the order of hundreds of micrometers for sufficient starlight suppression to enable the detection and study of Earth-like exoplanets around nearby Sun-like stars. We describe tests conducted to demonstrate deployment repeatability of two key structural subsystems of the “furled” starshade architecture—the petal and the inner disk. Together, the petals and the inner disk create the in-plane shape of a starshade. Test articles to represent the petal and inner disk subsystems were constructed at relevant scales for a 26-m-diameter starshade. These test articles were subjected to stowage-and-deployment cycles and their shapes were measured. The measured performance—tens of parts per million of petal strain after deployment, and hundreds of micrometers of inner disk deployment accuracy—was found to be within required allocations.

High contrast imaging of exoplanets is currently an upsurging science. Images of exoplanets carry information about its atmosphere, which can show traces of biomarkers. Since the first exoplanet was directly imaged in 2004 (2M1207), new instruments dedicated to high contrast imaging have been installed on the biggest ground based observatories on Earth (Paranal, Gemini). The exoplanets that are targeted by these instruments are giant gaseous bodies known as Hot Jupiters.The next goal is to image exoplanets smaller in size, which will also make them less luminous, and closer to their host star.Future systems dedicated to this kind of imaging hence have to be capable of imaging a planet closer than 0.1 arc seconds to its host star and up to 10^10 times dimmer than the star. These capabilities, unachievable today, can only be reached with a space based giant telescope that will necessarily have to be segmented. The optical quality of such an imaging system will require a perfect wavefront control on levels smaller than a nanometer.This thesis is addressing methods trying to understand, sense and control these aberrations with wavefront sensing and control techniques. Considering that the ultimate goal is to image an Exo-Earth at a flux ratio of 10-10, the wavefront in these systems needs to be controlled on the picometer level.Strategies for the creation and maintenance of deep contrasts on segmented aperture telescopes like the Large UV/Optical/IR Surveyor (LUVOIR) telescope, one of the NASA flagship designs, are being developed. Further, laboratory demonstrations of these methods are being performed on the High-contrast imager for Complex Aperture Telescopes (HiCAT) testbed, a system-level demonstrator for segmented coronagraphy., L'imagerie directe d'exoplanètes est une science en plein essor aujourd'hui. Les photos émis par l'exoplanète sont porteurs d'information sur la composition de son atmosphère, et témoins de biomarqueurs. Depuis la première planète imagée en 2004 (2M1207), des instruments dédiés à l'imagerie directe ont été mis en opération sur les plus grands observatoires au sol (Paranal, Gemini). Les planètes visées par ces systèmes sont des géantes gazeuses de type jupiters chauds.Le prochain défi est d'imager des planètes de plus petite taille, donc moins lumineuses, et proches de leur étoile hôte.Les futurs systèmes dédiés à ce type d'imagerie devront donc imager une planète plus proche que 0.1 arcseconde de son étoile, et jusqu'à 10^10 fois plus ténue. Ces performances, inatteignables aujourd'hui, ne pourront être atteintes que dans l'espace à bord de télescopes géants qui seront forcément segmentés. La qualité optique nécessaire à une telle imagerie nécessitera par ailleurs une maîtrise parfaite du front d'onde, à des niveaux plus petits que le nanomètre.Cette thèse aborde des méthodes essayant de comprendre, détecter et contrôler ces aberrations avec des techniques de détection et de contrôle de front d'onde. Considérant que le but ultime est d'imager une Exo-Terre à un rapport de flux de 10-10, le front d'onde dans ces systèmes doit être contrôlé au niveau du picomètre.Des stratégies pour la création et le maintien de contrastes profonds sur des télescopes à ouverture segmentée comme le télescope Large UV/Optical/IR Surveyor (LUVOIR), l'un des modèles phares de la NASA, sont en cours de développement. En outre, des démonstrations en laboratoire de ces méthodes sont effectuées sur le banc optique High-contrast imager for Complex Aperture Telescopes (HiCAT), un démonstrateur au niveau du système pour la coronagraphie segmentée.

Large surveys with new-generation high-contrast imaging instruments are needed to derive the frequency and properties of exoplanet populations with separations from ~5 to 300 au. A careful assessment of the stellar properties is crucial for a proper understanding of when, where, and how frequently planets form, and how they evolve. The sensitivity of detection limits to stellar age makes this a key parameter for direct imaging surveys. Aims. We describe the SpHere INfrared survey for Exoplanets (SHINE), the largest direct imaging planet-search campaign initiated at the VLT in 2015 in the context of the SPHERE Guaranteed Time Observations of the SPHERE consortium. In this first paper we present the selection and the properties of the complete sample of stars surveyed with SHINE, focusing on the targets observed during the first phase of the survey (from February 2015 to February 2017). This early sample composed of 150 stars is used to perform a preliminary statistical analysis of the SHINE data, deferred to two companion papers presenting the survey performance, main discoveries, and the preliminary statistical constraints set by SHINE. Methods. Based on a large database collecting the stellar properties of all young nearby stars in the solar vicinity (including kinematics, membership to moving groups, isochrones, lithium abundance, rotation, and activity), we selected the original sample of 800 stars that were ranked in order of priority according to their sensitivity for planet detection in direct imaging with SPHERE. The properties of the stars that are part of the early statistical sample wererevisited, including for instance measurements from the Gaia Data Release 2. Rotation periods were derived for the vast majority of the late-type objects exploiting TESS light curves and dedicated photometric observations. Results. The properties of individual targets and of the sample as a whole are presented. © ESO 2021. SPHERE is an instrument designed and built by a consortium consisting of IPAG (Grenoble, France), MPIA (Heidelberg, Germany), LAM (Marseille, France), LESIA (Paris, France), Laboratoire Lagrange (Nice, France), INAF – Osservatorio di Padova (Italy), Observatoire de Genève (Switzerland), ETH Zürich (Switzerland), NOVA (Netherlands), ONERA (France) and ASTRON (Netherlands) in collaboration with ESO. SPHERE was funded by ESO, with additional contributions from CNRS (France), MPIA (Germany), INAF (Italy), FINES (Switzerland) and NOVA (Netherlands). SPHERE also received funding from the European Commission Sixth and Seventh Framework Programmes as part of the Optical Infrared Coordination Network for Astronomy (OPTICON) under grant number RII3-Ct-2004-001566 for FP6 (2004–2008), grant number 226 604 for FP7 (2009–2012) and grant number 312430 for FP7 (2013–2016). This research has made use of the SIMBAD database and Vizier services, operated at CDS, Strasbourg, France and of the Washington Double Star Catalog maintained at the US Naval Observatory. This work has made use of data from the European Space Agency (ESA) mission Gaia (https://www.cosmos.esa.int/gaia), processed by the Gaia Data Processing and Analysis Consortium (DPAC, https://www.cosmos.esa.int/web/gaia/dpac/consortium). Funding for the DPAC has been provided by national institutions, in particular the institutions participating in the Gaia Multilateral Agreement. This paper includes data collected with the TESS mission, obtained from the MAST data archive at the Space Telescope Science Institute (STScI). Funding for the TESS mission is provided by the NASA Explorer Program. STScI is operated by the Association of Universities for Research in Astronomy, Inc., under NASA contract NAS 5–26555. This paper has made use of data products available in ESO archive. Program ID: 60.A-9036(A); 072.C-0488(E) (PI Mayor), 074.C-0364(A) (PI Robichon), 074.C-0037(A) (PI Gunther), 075.C-0202(A) (PI Gunther), 075.C-0689(A) (PI Galland), 076.C-0010(A) (PI Gunther), 077.C-0012(A) (PI Gunther), 077.C-0295(D) (PI Galland), 078.D-0245(C) (PI Dall), 079.C-0046(A) (PI Gunther), 080.D-0151(A) (PI Hatzes), 080.C-0712(A) (PI Desort), 180.C-0886(A) (PI Bonfils), 082.C-0718(B) (PI Bonfils), 082.C-0427(A) (PI Doellinger), 082.C-0390(A) (PI Weise), 183.C-0437(A) (PI Bonfils), 083.C-0794(A) (PI Chauvin), 084.C-1039(A) (PI Chauvin), 184.C-0815(B) (PI Desort), 089.C-0732(A) (PI Lo Curto), 191.C-0873(D) (PI Bonfils), 192.C-0224(A) (PI Lagrange), 097.C-0864(B) (PI Lannier), 098.C-0739(A) (PI Lagrange), 099.C-0205(A) (PI Lagrange), 099.C-0458(A) (PI Lo Curto), 1101.C-0557(A) (PI Lagrange). We have used data from the WASP public archive in this research. The WASP consortium comprises of the University of Cambridge, Keele University, University of Leicester, The Open University, The Queen’s University Belfast, St. Andrews University and the Isaac Newton Group. Funding for WASP comes from the consortium universities and from the UK’s Science and Technology Facilities Council. Based on data retrieved from the SOPHIE archive at Observatoire de Haute-Provence (OHP), available at http://atlas.obs-hp.fr/sophie/. We thank the anonymous referee for useful comments. S.D., V.D., D.M. and R.G. acknowledge the support by INAF/Frontiera through the “Progetti Premiali” funding scheme of the Italian Ministry of Education, University, and Research, the PRIN-INAF 2019 “Planetary systems at young ages” (PLATEA) and the ASI-INAF agreement n.2018-16-HH.0. AV acknowledges funding from the European Research Council (ERC) under the European Union’s Horizon 2020 research and innovation programme (grant agreement No. 757561). A.M.L. acknowledges funding from Agence Nationale de la Recherche (France) under contract number ANR-14-CE33-0018. J.C. was supported by SC Space Grant and Fulbright Colombia. M.B. acknowledges funding by the UK Science and Technology Facilities Council (STFC) grant no. ST/M001229.

METIS is one of the first three instruments for the ELT, Europe’s next-generation ground-based telescope. It will offer imaging, coronagraphy and spectroscopy in the L, M and N bands for general-purpose science in astrophysics. Among its main science drivers are circumstellar disks and extrasolar planets observations, which requires demanding high contrast imaging techniques. In that framework, METIS will be equipped with state-of-the-art phase mask coronagraphs: Apodizing Phase Plate (APP) and Annular Grooves Phase Mask (AGPM). Manufacturing the AGPM coronagraphs is a complex process that requires performance assessment with specific testing before implementation into the instrument. At Department of Astrophysics (CEA Saclay, France), responsible for the testing of the N-band AGPMs, a previously available test bench with a telescope simulator and cryogenic facility has been upgraded to comply with the AGPM tests requirements. This paper presents these requirements and describes the test bench design adopted. Then, based on preliminary results, we discuss the original solutions that permitted to reach our goals.

Focal plane wavefront sensing is an elegant solution for wavefront sensing since near-focal images of any source taken by a detector show distortions in the presence of aberrations. Non-Common Path Aberrations and the Low Wind Effect both have the ability to limit the achievable contrast of the finest coronagraphs coupled with the best extreme adaptive optics systems. To correct for these aberrations, the Subaru Coronagraphic Extreme Adaptive Optics instrument hosts many focal plane wavefront sensors using detectors as close to the science detector as possible. We present seven of them and compare their implementation and efficiency on SCExAO. This work will be critical for wavefront sensing on next generation of extremely large telescopes that might present similar limitations., Comment: SPIE proceeding : Astronomical Telescopes + Instrumentation 2020. arXiv admin note: text overlap with arXiv:1912.10179

The study of the more than 4000 exoplanets known to date allowed to start constraining theoretical models on their formation, migration and dynamical evolution. However, theses models are yet poorly constrained at young ages, because only few young planets were studied to date.A complete study of exoplanets just after their formation must be done for all separations, in order to give constraint on these models.Giant planets are important in this study, because they dynamically dominate their systems and therefore dominate their architecture.The goal of my PhD thesis was to prepare this exhaustive study of the giant planets after their formation for all the separations, by coupling three techniques that are complementary in the separations and in the planets' parameters they probe: the radial velocity method, the direct imaging method and the absolute astrometry method. During my PhD, I have studied the population of young giant planets from individual to statistical scale.First, I carried out a statistical analysis of 177 young stars from three radial velocity surveys with the HARPS instrument of the 3.6m at La Silla Observatory in Chile and with the SOPHIE instrument of the 1.93m at the Observatory of Haute-Provence in France.I computed the occurrence rate of young giant planets for periods lower than 1000 days.Then, I studied several individual systems coupling radial velocity, direct imaging and Hipparcos and Gaia absolute astrometry.To perform these analyzes, I developed a Bayesian analysis code, based on an MCMC, combining the data from these three techniques. These analyzes permit to constrain the dynamic mass of the companions of some of these systems and therefore to test the evolutionary models that are used in direct imaging.Finally, I participated in the improvement of the MESS II tool, which estimates the detection limits, combining radial velocity and direct imaging, so that it takes into account data from Hipparcos and Gaia. This will allow to obtain better detection limits at intermediate separations (2-5 au).; Les plus de 4000 exoplanètes connues à ce jour, ont permis d'apporter des contraintes sur les modèles théoriques de formation, de migration et d'évolution dynamique de ces dernières.Cependant, ces contraintes sont particulièrement limitées aux jeunes âges, par manque d'objets connus.Une étude des exoplanètes juste après leur formation et pour toutes les séparations est nécessaire pour poser des contraintes sur ces modèles. Les planètes géantes sont importantes dans cette étude, car celles-ci dominent dynamiquement leurs systèmes et dominent donc la formation de ces derniers.Le but de ma thèse a été de préparer cette étude exhaustive des planètes géantes juste après leur formation et pour toutes les séparations.Pour cela j'ai combiné trois techniques complémentaires dans les séparations et les paramètres des planètes qu'elles contraignent : la méthode des vitesses radiales, la méthode d'imagerie directe et la méthode d'astrométrie absolue. J'ai ainsi caractérisé la population des planètes jeunes de l'échelle individuelle à l'échelle statistique.J'ai d'abord effectué une analyse statistique de 177 étoiles jeunes, à partir de trois surveys en vitesses radiales menés avec l'instrument HARPS du 3.6m de l'observatoire de La Silla au Chili et l'instrument SOPHIE du 1.93m de l'observatoire de Haute-Provence en France.J'en ai déduit le taux d'occurrence des planètes géantes jeunes pour les périodes inférieures à 1000 jours.Ensuite, j'ai effectué l'analyse dynamique de plusieurs systèmes en combinant vitesses radiales, imagerie directe et astrométrie d'Hipparcos et Gaia. Pour effectuer ces analyses, j'ai élaboré un code d'analyse bayésienne, basé sur un MCMC, combinant les données de ces trois techniques. Ces analyses m'ont permis de contraindre la masse dynamique des compagnons de certains de ces systèmes, permettant ainsi de tester les modèles d'évolutions utilisés en imagerie directe.Enfin, j'ai participé à l'amélioration de l'outil MESS II, qui estime des limites de détection combinant vitesses radiales et imagerie directe, afin qu'il prenne en compte les données d'Hipparcos et Gaia. Cela permettra d'obtenir de meilleures limites de détection aux séparations intermédiaires (2-5 au).

The SPEED project aims at developing and testing key recipes for high-contrast imaging at small angular separations with unfriendly telescope apertures. SPEED combines optimized segmented aperture coronagraphy, dual-deformable mirrors wavefront control and shaping architecture for creating a dark hole in the scientific image by deformable mirror (DM) actuation. The challenge is to overcome the various fundamental limitations for quasi-static speckle calibration at very small angular separations. We report on the progress made in elaborating an accurate simulated model of our instrument in preparation for the wavefront control and wavefront shaping strategy with a multi-DM setup.

The NEW EARTH Laboratory (NRC Extreme Wavefront control for Exoplanet Adaptive optics Research Topics at Herzberg) has recently been completed at NRC in Victoria. NEW EARTH is the first Canadian test-bed dedicated to high-contrast imaging. The bench optical design allows a wide range of applications that could require turbulent phase screens, segmented pupils, or custom coronagraphic masks. Super-polished off-axis parabolas are implemented to minimize optical aberrations, in addition to a 468-actuator ALPAO deformable mirror and a Shack Hartmann WFS. The laboratory’s immediate goal is to validate the Fast Atmospheric Self-coherent camera Technique (FAST). The first results of this technique obtained in the NEW EARTH laboratory with a Tilt-Gaussian-Vortex focal plane mask, a reflective Lyot stop and Coherent Differential Imaging are encouraging. Future work will be aimed at expanding this technique to broader wavebands in the context of extremely large telescopes and at visible bands for space-based observatories.

The field of exoplanet research is rapidly advancing through the development of new technology, observing techniques, and post-processing methods. In the last 30 years, thousands of exoplanet candidates have been found through various methods. These discoveries have revealed a zoo of exoplanetary systems looking very different from our own Solar System. This dissertation contains two very distinctive parts, both related to the measurement of exoplanetary systems.The first part of this dissertation, Chapter 2, investigates 8 light curves found in the Kepler data archive. These light curves show periodic brightening events that look different from a normal exoplanet signal. The second part of this dissertation, focuses on high-contrast imaging (HCI). Current HCI instruments are more sensitive to exoplanets orbiting far out from their host star. To probe the regions close-in to the star, the extreme adaptive optics (XAO) subsystem needs to improve in performance. Specifically, the XAO does not correct well enough for the continuous evolution of turbulence during the time it takes the XAO to measure the phase and subsequently correct for the aberrations (resulting in the servo-lag error). This dissertation focuses on data-driven predictive control to address the servo-lag error.

Understanding the formation, the evolution and the diversity of extrasolar planets is an important purpose in modern astrophysics. More than 4,000 objects have been discovered since the first discovery of an exoplanet orbiting a solar-type star in 1995. Knowledge about atmospheres of these planets is crucial to determine the conditions for the appearance of life. However, it remains unknown while direct imaging technique would be a powerfull technique to study their spectra.Exoplanet imaging is limited by the large contrast and the small distance which exists between exoplanets and stars. Techniques optimized for high-contrast imaging such as coronography are therefore essential. Coronographs attenuate the light of stars without affecting the fait signal of their circumstellar environments. However, atmospheric turbulence, as well as polishing defects, alignment errors and thermal expansions of telescopes which can vary over time still limit their performance. Techniques dedicated to active correction of aberrations relied on deformable mirrors and wavefront sensors will equip future high-contrast imaging facilities such as WFIRST, HaBEX or LUVOIR spacecrafts or the Extremely Large telescopes.The instrument Très Haute Dynamique 2 (THD2) located at Observatoire de Paris/LESIA is a testbed dedicated to such projects. During this PhD, several wavefront sensor and control algorithms, originally developed by different teams in Europe and the United-States, were tested and compared under the same environmental conditions on the THD2. During these tests, the pair-wise sensor combined with an electric field conjugation technique has also demonstrated excellent contrast performance under spatial conditions, without any modification of the instrument optical path. This method was then implemented on the high-contrast VLT/SPHERE instrument in which we performed improvements in contrast of several orders of magnitude with the calibration unit.; Comprendre la formation, l'évolution et la surprenante diversité des planètes extrasolaires est un des grands enjeux de l'astrophysique moderne. En deux décennies, de nombreuses découvertes ont déjà révélé la nature complexe de plus de 4000 objets. Pourtant, on connaît peu de choses sur l'atmosphère de ces planètes alors qu’il s’agit d’un point crucial pour déterminer les conditions d'apparition de la vie ailleurs que sur Terre. L'imagerie directe est une technique appropriée à l'étude spectrale des atmosphères d'exoplanètes similaires à celles du Système Solaire.L'imagerie des exoplanètes est cependant limitée par le très grand contraste et par la proximité entre exoplanètes et étoiles. Des techniques optimisées pour l'imagerie à très haute dynamique telles que la coronographie sont donc indispensables. Les coronographes atténuent la lumière des étoiles sans affecter le signal provenant de leurs environnements proches pour le révéler. Cependant, la turbulence atmosphérique, ainsi que les défauts de polissage, les erreurs d'alignement et les dilatations thermiques des télescopes qui peuvent varier avec le temps limitent encore leurs performances. Des techniques de correction active d'aberrations composées de miroirs déformables et d'analyseurs de front d'onde équiperont alors les futurs instruments haute-dynamiques tels que les projets spatiaux WFIRST, HaBEX ou LUVOIR ou encore les instruments aux foyers des Extremely Large telescopes.L'instrument Très Haute Dynamique 2 (THD2) situé à l'Observatoire de Paris/LESIA est un banc de test dédié à ce type d'activité. Durant cette thèse, plusieurs algorithmes d'analyse et de contrôle du front d'onde développés par différentes équipes en Europe et aux États-Unis ont été testés et comparés dans les mêmes conditions de stabilité sur le THD2. Lors de ces tests, la technique d'analyse pair-wise associée à une technique de conjugaison du champ électrique a d'ailleurs démontré d'excellentes performances en contraste dans des conditions spatiales, sans aucune modification du design optique de l'instrument. Fort de cette expérience, cette méthode a alors été implémentée sur l'instrument haute-dynamique VLT/SPHERE dont les résultats sur source interne laissent entrevoir des améliorations en contraste de plusieurs ordres de grandeur.

Massive stars like company. However, low-mass companions have remained extremely difficult to detect at angular separations ($\rho$) smaller than 1" (~1000-3000 au considering typical distance to nearby massive stars) given the large brightness contrast between the companion and the central star. Constraints on the low-mass end of the companions mass-function for massive stars are however needed, for example to help distinguishing between various scenarios for the formation of massive stars. To obtain statistically significant constraint on the presence of low-mass companions beyond the typical detection limit of current surveys ($\Delta \mathrm{mag} \lesssim 5$ at $\rho \lesssim 1$"), we initiated a survey of O and Wolf-Rayet stars in the Carina region using the SPHERE coronagraphic instrument on the VLT. In this first paper, we aim to introduce the survey, to present the methodology and to demonstrate the capability of SPHERE for massive stars using the multiple system QZ~Car. High-contrast imaging techniques, such as angular- and spectral-differential imaging techniques as well as PSF-fitting, were applied to detect and measure the relative flux of companions in each spectral channel of the instrument. We detected 19 sources around the QZ~Car system with detection limits of 9~mag at $\rho > 200$~mas for IFS and as faint as 13~mag at $\rho$ > 1".8 for IRDIS (corresponding to sub-solar masses for potential companions). All but two are reported here for the first time. Based on this proof of concept, we showed that VLT/SPHERE allows us to reach the sub-solar mass regime of the companion mass function. This paves the way for this type of observation with a large sample of massive stars to provide novel constraints on the multiplicity of massive stars in a region of the parameter space that has remained inaccessible so far., Comment: Submitted and accepted by A&A. 17 pages, 10 figures

Quantitative phase imaging (QPI) is an emerging label-free modality that attracts significant interest in biomedicine in general and neuroscience in particular. Based on the principle of interferometry, QPI precisely maps the optical pathlength induced by the sample, and, thus, can visualize extremely transparent samples. The QPI field has grown rapidly in the past decade, and reliable instruments have been developed for in-depth biological studies. One particular figure of merit associated with QPI techniques describes the temporal phase sensitivity of instruments. Recently, several common path interferometry methods have been developed, which yield high stability and nanometer scale pathlength sensitivity. In neuroscience, QPI has shown unique capabilities in quantifying neural growth and dynamics in cell cultures, as well as high contrast imaging of brain tissue slices. In this paper, we review the principles of QPI, novel QPI technology, advances in data processing, and a number of exciting applications in neuroscience.