arXiv subjects

Laurent A. Pueyo

Publications and source records attributed to Laurent A. Pueyo.

4 recordsLinked to original sources

arXiv2026

JWST telemetry combined with active coronagraphy: raw contrast predictions for exoplanet imaging with the Habitable Worlds Observatory

We provide a quantification of the technological gap between the James Webb Space Telescope (JWST) and the Habitable Worlds Observatory (HWO) for the goal of exo-Earth imaging around Sun-like stars at the $10^{-10}$ raw contrast level. We use JWST's in-flight telemetry of the primary segmented mirror to simulate a JWST-like telescope equipped with a modern coronagraph instrument, inspired by the Roman Space Telescope (RST) Coronagraphic Instrument (CGI), featuring an Apodized Pupil Lyot Coronagraph and active deformable mirror wavefront control on a segmented, unobstructed, off-axis telescope. We show that it can achieve around $10^{-10}$ raw contrast for very bright stars (brighter than magnitude 4) for fast control frequencies of 100 Hz, but that this level of control still lacks sufficient signal to correct JWST-amplitude errors for fainter stars. We show that an improvement of a factor of ten in wavefront stability is sufficient to extend this capability to a $10^{-10}$ raw contrast across all considered control frequencies (1 Hz to 100 Hz), assuming no reaction wheel vibrations, for stars up to a magnitude of 11. These results establish a new quantitative benchmark linking JWST's demonstrated thermo-mechanical stability to HWO's requirements, showing that active wavefront control relaxes the structural stability demands on the observatory, and identifying wavefront stability as the critical technological gap that must be closed for HWO to achieve its exo-Earth imaging goals.

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arXiv2026

CATKit2-HCI: a collaborative framework for advancing high-contrast coronagraph testbeds

High-contrast exoplanet imaging requires dedicated laboratory testbeds for the development and validation of coronagraph architectures, wavefront sensing and control methods, calibration strategies, and system-level observing concepts. These testbeds often share similar software needs, yet many tools are developed independently at each institution. The CATKit2-High-Contrast-Imaging collaboration, or CATKit2-HCI, addresses this gap by providing a shared software framework for reusable HCI infrastructure. Built on top of CATKit2, an open-source hardware control and synchronization framework originally developed for the High-contrast Imager for Complex Aperture Telescopes (HiCAT) testbed at the Space Telescope Science Institute, CATKit2-HCI provides the collaborative layer for HCI-specific algorithms, calibration tools, diagnostics, visualization, and performance metrics. The collaboration currently includes multiple coronagraph testbeds in the United States and Europe. Its goals are to reduce duplicated software development, improve code quality through shared review, enable more direct comparison of results across facilities, and facilitate the movement of students, postdoctoral researchers, and collaborators between laboratories. We describe the motivation, architecture, collaboration model, shared technical capabilities, and early cross-testbed examples of CATKit2-HCI as a framework for accelerating coronagraph technology development.

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arXiv2022

Adaptive optics performance of a simulated coronagraph instrument on a large, segmented space telescope in steady state

Directly imaging Earth-like exoplanets (``exoEarths'') with a coronagraph instrument on a space telescope requires a stable wavefront with optical path differences limited to tens of picometers RMS during exposure times of a few hours. While the structural dynamics of a segmented mirror can be directly stabilized with telescope metrology, another possibility is to use a closed-loop wavefront sensing and control system in the coronagraph instrument that operates during the science exposures to actively correct the wavefront and relax the constraints on the stability of the telescope. In this paper, we present simulations of the temporal filtering provided using the example of LUVOIR-A, a 15~m segmented telescope concept. Assuming steady-state aberrations based on a finite element model of the telescope structure, we (1)~optimize the system to minimize the wavefront residuals, (2)~ use an end-to-end numerical propagation model to estimate the residual starlight intensity at the science detector, and (3)~predict the number of exoEarth candidates detected during the mission. We show that telescope dynamic errors of 100~pm~RMS can be reduced down to 30~pm~RMS with a magnitude 0 star, improving the contrast performance by a factor of 15. In scenarios where vibration frequencies are too fast for a system that uses natural guide stars, laser sources can increase the flux at the wavefront sensor to increase the servo-loop frequency and mitigate the high temporal frequency wavefront errors. For example, an external laser with an effective magnitude of -4 allows the wavefront from a telescope with 100~pm~RMS dynamic errors and strong vibrations as fast as 16~Hz to be stabilized with residual errors of 10~pm~RMS thereby increasing the number of detected planets by at least a factor of 4.

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arXiv2014

Gemini Planet Imager Observational Calibrations VI: Photometric and Spectroscopic Calibration for the Integral Field Spectrograph

The Gemini Planet Imager (GPI) is a new facility instrument for the Gemini Observatory designed to provide direct detection and characterization of planets and debris disks around stars in the solar neighborhood. In addition to its extreme adaptive optics and corona graphic systems which give access to high angular resolution and high-contrast imaging capabilities, GPI contains an integral field spectrograph providing low resolution spectroscopy across five bands between 0.95 and 2.5 $μ$m. This paper describes the sequence of processing steps required for the spectro-photometric calibration of GPI science data, and the necessary calibration files. Based on calibration observations of the white dwarf HD 8049B we estimate that the systematic error in spectra extracted from GPI observations is less than 5%. The flux ratio of the occulted star and fiducial satellite spots within coronagraphic GPI observations, required to estimate the magnitude difference between a target and any resolved companions, was measured in the $H$-band to be $Δm = 9.23\pm0.06$ in laboratory measurements and $Δm = 9.39\pm 0.11$ using on-sky observations. Laboratory measurements for the $Y$, $J$, $K1$ and $K2$ filters are also presented. The total throughput of GPI, Gemini South and the atmosphere of the Earth was also measured in each photometric passband, with a typical throughput in $H$-band of 18% in the non-coronagraphic mode, with some variation observed over the six-month period for which observations were available. We also report ongoing development and improvement of the data cube extraction algorithm.

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