High-contrast imager for complex aperture telescopes (HiCAT): 7. Dark zone demonstration with fully segmented aperture coronagraph

Soummer, Rémi; Laginja, Iva; Will, Scott D.; Perrin, Marshall D.; Noss, James; Por, Emiel H.; Redmond, Susan; Pourcelot, Raphaël; Sahoo, Ananya; Petrone, Peter; Brooks, Keira; Pueyo, Laurent; Nickson, Bryony; Maclay, Matthew; Brady, Gregory R.; Comeau, Thomas; Fowler, J.; Glazer, Kelsey; Gontrum, Rob; Hagopian, John G.; Jolivet, Théo; Kautz, Maggie; Leboulleux, Lucie; McChesney, Evelyn; Mugnier, Laurent M.; N’Diaye, Mamadou; Nguyen, Meiji M.; Olszewski, H.; Pogorelyuk, Leonid; Prothro, Jaret; Sauvage, Jean-François; Scott, Nathan; Shiri, Ron; Sivaramakrishnan, Anand; Subedi, Hari; Weinstock, Sam; Zhang, Rebecca

doi:10.1117/12.2594684

Cited by 3 publications

(4 citation statements)

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“…HiCAT is a testbed dedicated to technology demonstrations for coronagraphy on segmented-aperture space observatories, with the intent of being directly traceable to a future HWO-like mission 10 – 17 These technologies include Lyot coronagraphy, high-order WFS&C for generating and stabilizing dark zones, and low-order wavefront sensing (LOWFS) 18 . HiCAT operates in a mid-contrast regime (10−7 to 10−8) which approaches the limit achievable outside of a vacuum environment.…”

Section: Methodsmentioning

confidence: 99%

High-order coronagraphic wavefront control with algorithmic differentiation: first experimental demonstration

Will,

Perrin,

Por

et al. 2023

J. Astron. Telesc. Instrum. Syst.

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Future space-based coronagraphs will rely critically on focal-plane wavefront sensing and control with deformable mirrors (DMs) to reach deep contrast by mitigating optical aberrations in the primary beam path. Until now, most focal-plane wavefront control algorithms have been formulated in terms of Jacobian matrices, which encode the predicted effect of each DM actuator on the focal-plane electric field. A disadvantage of these methods is that Jacobian matrices can be cumbersome to compute and manipulate, particularly when the number of DM actuators is large. Recently, we proposed a new class of focal-plane wavefront control algorithms that utilize gradient-based optimization with algorithmic differentiation to compute wavefront control solutions while avoiding the explicit computation and manipulation of Jacobian matrices entirely. In simulations using a coronagraph design for the proposed Large UV/Optical/Infrared Surveyor, we showed that our approach reduces overall CPU time and memory consumption compared to a Jacobian-based algorithm. Here, we expand on these results by implementing the proposed algorithm on the High-contrast Imager for Complex Aperture Telescopes tested at the Space Telescope Science Institute and present initial experimental results, demonstrating contrast suppression capabilities equivalent to Jacobian-based methods.

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Section: Methodsmentioning

confidence: 99%

High-order coronagraphic wavefront control with algorithmic differentiation: first experimental demonstration

Will,

Perrin,

Por

et al. 2023

J. Astron. Telesc. Instrum. Syst.

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“…The existing high-contrast testbeds and recent results are described in [177]. These testbeds can be in air [167,170,178,179] or in a vacuum [180,181]. Once the techniques have been validated in the laboratory, certain instruments already installed on the telescope offer the possibility of technical validation using internal laser sources during daylight: SCEXAO at Subaru Telescope [182], SPHERE at Very Large Telescope [175], MagAO at Magellan Telescope [183], KPIC at Keck Observatory [184].…”

Section: From Laboratory To On-sky Validationmentioning

confidence: 99%

Imaging exoplanets with coronagraphic instruments

Galicher¹,

Mazoyer²

2024

Comptes Rendus. Physique

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Exoplanetary science is a very active field of astronomy nowadays, with questions still opened such as how planetary systems form and evolve (occurrence, process), why such a diversity of exoplanets is observed (mass, radius, orbital parameters, temperature, composition), and what are the interactions between planets, circumstellar disk and their host star. Several complementary methods are used for the detection of exoplanets. Among these, imaging aims at the direct detection of the light reflected, scattered or emitted by exoplanets and circumstellar disks. This allows their spectral and polarimetric characterization. Such imaging remains challenging because of the large luminosity ratio (10 4 -10 10 ) and the small angular separation (fraction of an arcsecond) between the star and its environment. Over the past two decades, numerous techniques, including coronagraphy, have been developed to make exoplanet imaging a reality.This paper gives a broad overview of the subsystems that make up a coronagraphic instrument for imaging exoplanetary systems. It is especially intended for non-specialists or newcomers in the field. We explain the principle of coronagraphy and propose a formalism to understand their behavior. We discuss the impact of wavefront aberrations on the performance of coronagraphs and how they induce stellar speckles in the scientific image. Finally, we present instrumental and signal processing techniques used for on-sky minimization or a posteriori calibration of these speckles in order to improve the performance of coronagraphs.Résumé. L'exoplanétologie est un domaine très actif de l'astronomie moderne avec des questions encore ouvertes : comment les systèmes planétaires se forment-ils et évoluent-ils ; pourquoi une telle diversité d'exoplanètes est-elle observée (masse, rayon, paramètres orbitaux, température, composition) ; quelles sont les interactions entre les planètes, les disques circumstellaires et leur étoile hôte ? Plusieurs méthodes complémentaires sont utilisées pour la détection d'exoplanètes. Parmi celles-ci, l'imagerie permet la détection directe de la lumière réfléchie, diffusée ou émise par les exoplanètes et les disques circumstellaires. Ceci permet une caractérisation spectrale et polarimétrique. Obtenir une image d'exoplanète n'est cependant pas simple en raison du grand rapport de luminosité (10 4 -10 10 ) et de la faible séparation angulaire (fraction de seconde d'angle) entre l'étoile et son environnement. Depuis deux décennies, de nombreuses techniques, dont la coronographie, ont été développées pour faire de l'imagerie des exoplanètes une réalité.

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“…Our second, and most recent, paper 6 described the first experimental demonstration of AD-based HOWFSC algorithms, using the High-contrast Imager for Complex Aperture Telescopes (HiCAT) coronagraph testbed at the Space Telescope Science Institute in Baltimore, MD. 21 HiCAT, whose primary objective is to develop and demonstrate coronagraphy techniques for segmented-aperture systems, supports several Lyot coronagraph varieties including the apodized pupil Lyot coronagraph and phase apodized pupil Lyot coronagraph (PAPLC), has a telescope simulator with an IrisAO segmented-aperture DM, a low-order wavefront sensor, and two Boston Micromachines Kilo-DMs. One DM is approximately conjugated to HiCAT entrance pupil, while the other is located 300 mm downstream, corresponding to a Fresnel number of approximately N F ≈ 98 at the central operating wavelength of 638 nm.…”

Section: First Experimental Demonstrationsmentioning

confidence: 99%

“…Since then, HiCAT has undergone a significant redevelopment of its hardware and software infrastructure, which have substantially improved the speed of the HOWFSC loop, integrated a parallel LOWFSC loop, and improved the achievable contrast to below 10 −8 in monochromatic light and 10 −7 over 6% fractional bandwidth. 21,22 Our planned experiments with HiCAT later in 2023 will focus on demonstrations at higher contrast, in non-monochromatic light, with a smaller inner working angle, and with coronagraph architectures relevant to HWO, such as the APLC and PAPLC.…”

Section: Experiments With Coronagraph Testbeds At Nasa Goddard and Sp...mentioning

confidence: 99%

High-contrast Jacobian-free wavefront control: simulations, experimental results, and extensions to adaptive control

Will,

Groff,

Soummer

et al. 2023

Techniques and Instrumentation for Detection of Exoplanets XI

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In recent work, we numerically and experimentally demonstrated a new approach to high-contrast wavefront control based on the combination of nonlinear optimization with algorithmic differentiation, which we termed algorithmic differentiation wavefront control (ADWC). ADWC is more computationally efficient than Jacobianbased control algorithms for deformable mirror (DM) actuator counts and focal plane sizes relevant to the planned Habitable Worlds Observatory, which potentially opens a path toward on-orbit wavefront sensing and control. Here, we review these results with a view toward their potential impact on NASA's planned Habitable Worlds Observatory and describe ongoing simulations and experiments, including extensions to adaptive control.

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High-contrast imager for complex aperture telescopes (HiCAT): 7. Dark zone demonstration with fully segmented aperture coronagraph

Cited by 3 publications

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High-order coronagraphic wavefront control with algorithmic differentiation: first experimental demonstration

High-order coronagraphic wavefront control with algorithmic differentiation: first experimental demonstration

Imaging exoplanets with coronagraphic instruments

High-contrast Jacobian-free wavefront control: simulations, experimental results, and extensions to adaptive control

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