Analytical model-based analysis of long-exposure images fromground-based telescopes

The search for Earth-like exoplanets requires high-contrast and high-angular resolution instruments, which designs can be very complex: they need an adaptive optics system to compensate for the effect of the atmospheric turbulence on image quality and a coronagraph to reduce the starlight and enable the companion imaging. During the instrument design phase and the error budget process, studies of performance as a function of optical errors are needed and require multiple end-to-end numerical simulations of wavefront errors through the optical system. In particular, the detailed analysis of long-exposure images enables to evaluate the image quality (photon noise level, impact of optical aberrations and of adaptive optics residuals, etc.). Nowadays simulating one long but finite exposure image means drawing several thousands of random frozen phase screens, simulating the image associated with each of them after propagation through the imaging instrument, and averaging all the images. Such a process is time consuming, demands a great deal of computer resources, and limits the number of parametric optimization. We propose an alternative and innovative method to directly express the statistics of ground-based images for long but finite exposure times. It is based on an analytical model, which only requires the statistical properties of the atmospheric turbulence. Such a method can be applied to optimize the design of future instruments such as SPHERE+ (VLT) or the planetary camera and spectrograph (PCS - ELT) or any ground-based instrument.Comment: 7 pages, 0 figur

Connecting the astronomical testbed community -- the CAOTIC project: Optimized teaching methods for software version control concepts

Laboratory testbeds are an integral part of conducting research and developing technology for high-contrast imaging and extreme adaptive optics. There are a number of laboratory groups around the world that use and develop resources that are imminently required for their operations, such as software and hardware controls. The CAOTIC (Community of Adaptive OpTics and hIgh Contrast testbeds) project is aimed to be a platform for this community to connect, share information, and exchange resources in order to conduct more efficient research in astronomical instrumentation, while also encouraging best practices and strengthening cross-team connections. In these proceedings, we present the goals of the CAOTIC project, our new website, and we focus in particular on a new approach to teaching version control to scientists, which is a cornerstone of successful collaborations in astronomical instrumentation.Comment: 15 pages, 6 figures, 2 tables; SPIE proceedings Astronomical Telescopes + Instrumentation 2022, 12185-11

James Webb Space Telescope Optical Simulation Testbed I: Overview and First Results

The James Webb Space Telescope (JWST) Optical Simulation Testbed (JOST) is a tabletop workbench to study aspects of wavefront sensing and control for a segmented space telescope, including both commissioning and maintenance activities. JOST is complementary to existing optomechanical testbeds for JWST (e.g. the Ball Aerospace Testbed Telescope, TBT) given its compact scale and flexibility, ease of use, and colocation at the JWST Science & Operations Center. We have developed an optical design that reproduces the physics of JWST's three-mirror anastigmat using three aspheric lenses; it provides similar image quality as JWST (80% Strehl ratio) over a field equivalent to a NIRCam module, but at HeNe wavelength. A segmented deformable mirror stands in for the segmented primary mirror and allows control of the 18 segments in piston, tip, and tilt, while the secondary can be controlled in tip, tilt and x, y, z position. This will be sufficient to model many commissioning activities, to investigate field dependence and multiple field point sensing & control, to evaluate alternate sensing algorithms, and develop contingency plans. Testbed data will also be usable for cross-checking of the WFS&C Software Subsystem, and for staff training and development during JWST's five- to ten-year mission.Comment: Proceedings of the SPIE, 9143-150. 13 pages, 8 figure

Integrated photonic-based coronagraphic systems for future space telescopes

The detection and characterization of Earth-like exoplanets around Sun-like stars is a primary science motivation for the Habitable Worlds Observatory. However, the current best technology is not yet advanced enough to reach the 10^-10 contrasts at close angular separations and at the same time remain insensitive to low-order aberrations, as would be required to achieve high-contrast imaging of exo-Earths. Photonic technologies could fill this gap, potentially doubling exo-Earth yield. We review current work on photonic coronagraphs and investigate the potential of hybridized designs which combine both classical coronagraph designs and photonic technologies into a single optical system. We present two possible systems. First, a hybrid solution which splits the field of view spatially such that the photonics handle light within the inner working angle and a conventional coronagraph that suppresses starlight outside it. Second, a hybrid solution where the conventional coronagraph and photonics operate in series, complementing each other and thereby loosening requirements on each subsystem. As photonic technologies continue to advance, a hybrid or fully photonic coronagraph holds great potential for future exoplanet imaging from space.Comment: Conference Proceedings of SPIE: Techniques and Instrumentation for Detection of Exoplanets XI, vol. 12680 (2023

Visible extreme adaptive optics on extremely large telescopes: Towards detecting oxygen in Proxima Centauri b and analogs

Looking to the future of exo-Earth imaging from the ground, core technology developments are required in visible extreme adaptive optics (ExAO) to enable the observation of atmospheric features such as oxygen on rocky planets in visible light. UNDERGROUND (Ultra-fast AO techNology Determination for Exoplanet imageRs from the GROUND), a collaboration built in Feb. 2023 at the Optimal Exoplanet Imagers Lorentz Workshop, aims to (1) motivate oxygen detection in Proxima Centauri b and analogs as an informative science case for high-contrast imaging and direct spectroscopy, (2) overview the state of the field with respect to visible exoplanet imagers, and (3) set the instrumental requirements to achieve this goal and identify what key technologies require further development.Comment: SPIE Proceeding: 2023 / 12680-6

Caroline Émilie « Lili » Bleeker

International audienceCaroline Émilie « Lili » Bleeker était une physicienne et auto-entrepreneuse néerlandaise. Après un doctorat sur les spectres des alcaloïdes, elle monte la première entreprise néerlandaise de production de matériel et d’instruments optiques. Elle signe notamment avec Frederik Zernike le brevet sur le microscope à contraste de phase, pour lequel le physicien obtient le prix Nobel de Physique en 1953. Elle se démarque également pour son engagement contre le nazisme lors de la Seconde Guerre Mondiale