Pierre Riaud

JWST: A mid-IR coronagraph for imaging extrasolar planets

A. Boccaletti, Pierre Riaud, Pierre Baudoz, J. Baudrand et autres

MIRI, the mid-IR instrument of JWST (JamesWebb Space Telescope), will include a coronagraphic device for which the ultimate goal is the detection and caracterization of extrasolar planets around nearby stars. In this paper, we describe the optical concept of MIRI and the …

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Optical design options for hypertelescopes and prototype testing

Erick Bondoux, S. Bosio, Rijuparna Chakraborty, Wassila Dali-Ali et autres

Hypertelescopes are large optical interferometric arrays, employing many small mirrors and a miniature pupildensifier before the focal camera, expected to produce direct images of celestial sources at high resolution. Their peculiar imaging properties, initially explored through analytical derivations, had been verified with …

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Evidence for two spatially separated UV continuum emitting regions in the Cloverleaf broad absorption line quasar

Dominique Sluse, Damien Hutsemékers, T. Anguita, L. Braibant et autres

\n Testing the standard Shakura-Sunyaev model of accretion is a challenging task because the central region of quasars where accretion takes place is unresolved with telescopes. The analysis of microlensing in gravitationally lensed quasars is one of the few techniques that can …

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POAMI: a Photon Orbital Momentum Interferometer for residual starlight cancellation in vectorial vortex coronagraphy

Pierre Riaud

The vector vortex coronagraph is a phase mask creating a phase ramp around its optical axis to cancel on-axis starlight in the focal plane of a telescope. This phase ramp also induces an orbital angular momentum (OAM) on the output stellar photons, …

Observing the Sun with micro-interferometric devices: a didactic experiment

Denis Defrère, Olivier Absil, C. Hanot, Pierre Riaud et autres

Measuring the angular diameter of celestial bodies has long been the main purpose of stellar interferometry and was its historical motivation. Nowadays, stellar interferometry is widely used for various other scientific purposes that require very high angular resolution measurements. In terms of …

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Towards laser guide stars for multi-aperture interferometry: an application to the hypertelescope

Paul D. Nuñez, A. Labeyrie, Pierre Riaud

Optical interferometry has been successful at achieving milliarcsecond resolution on bright stars. Imaging performance can improve greatly by increasing the number of baselines, which has motivated proposals to build large (∼100 m) optical interferometers with tens to hundreds of telescopes. It is …

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Direct imaging of extra-solar planets in star forming regions: Lessons learned from a false positive around IM Lupi

Dimitri Mawet, Olivier Absil, G. Montagnier, Pierre Riaud et autres

Context. Most exoplanet imagers consist of ground-based adaptive optics coronagraphic cameras which are currently limited in contrast, sensitivity and astrometric precision, but advantageously observe in the near-infrared window (1–5 μm). Because of these practical limitations, our current observational aim at detecting and …

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New high-density deformable mirrors for high-contrast imaging

Pierre Riaud

This paper presents a new architecture for deformable mirrors, suitable for adaptive optics (AO) observations. The performance of these systems directly depends on the density of actuators, which correct for wavefront errors. Therefore, deformable mirrors of large sizes are difficult to build …

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Instantaneous phase retrieval with the vector vortex coronagraph

Pierre Riaud, Dimitri Mawet, A. Magette

Coronagraphs are used as high-contrast imaging tools. However, it is well-known that the achievable contrast is primarily limited by wavefront aberrations in the optical train. Various kinds of devices and methods have been proposed to correct and calibrate these errors and, hence, …

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Nijboer-Zernike phase retrieval for high contrast imaging

Pierre Riaud, Dimitri Mawet, A. Magette

We introduce a novel phase retrieval method for astronomical applications based on the Nijboer-Zernike (NZ) theory of diffraction. We present a generalized NZ phase retrieval process that is not limited to small and symmetric aberrations and can therefore be directly applied to …

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Direct imaging of extra-solar planets in star forming regions

Dimitri Mawet, Olivier Absil, G. Montagnier, Pierre Riaud et autres

Context. Most exoplanet imagers consist of ground-based adaptive optics coronagraphic cameras which are currently limited in contrast, sensitivity and astrometric precision, but advantageously observe in the near-infrared window (1–5 μm). Because of these practical limitations, our current observational aim at detecting and …

us, cl, be, fr (code pays fourni par la source)

The quantum stellar interferometer

Pierre Riaud

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