A stellar coronograph for the COME-ON-PLUS adaptive optics
system

Beuzit, Jean-Luc; Mouillet, D.; Lagrange, A. M.; Paufique, J.

doi:10.1051/aas:1997370

Cited by 33 publications

(31 citation statements)

References 6 publications

(3 reference statements)

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“…Though it corresponds to an additional perturbation, a deterministic contribution can easily be calibrated. Nonetheless, observing acquisitions have shown that the major noise-source limitation in high-contrast imaging is another class of instrumental speckles, the quasi-static speckles (Beuzit et al 1997;Oppenheimer et al 2001;Marois et al 2003;Boccaletti et al 2003Boccaletti et al , 2004Hinkley et al 2007). Quasi-static speckles correspond to slowly varying instrumental wavefront aberrations (amplitude and phase errors) present in the system, which finally dominate the companion signal.…”

Section: Introductionmentioning

confidence: 99%

Speckle temporal stability in XAO coronagraphic images

Martínez

Loose

Carpentier

et al. 2012

A&A

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Context. The major source of noise limiting high-contrast imaging is caused by quasi-static speckles. Speckle noise originates from wavefront errors caused by various independent sources, and evolves on different timescales depending on their nature. An understanding of how quasi-static speckles originate from instrumental errors is paramount to the search for faint stellar companions. Instrumental speckles average to form a fixed pattern, which can be calibrated to a certain extent, but their temporal evolution ultimately limits this possibility. Aims. This study focuses on the laboratory evidence and characterization of the quasi-static pinned speckle phenomenon. Specifically, we examine the coherent amplification of the static speckle contribution to the noise variance in the scientific image, through its interaction with quasi-static speckles. Methods. The analysis of a time series of adaptively corrected, coronagraphic images recorded in the laboratory enables the characterization of the temporal stability of the residual speckle pattern in both direct and differential coronagraphic images. Results. We estimate that spoiled and rapidly evolving quasi-static speckles present in the system at the angstrom/nanometer level affect the stability of the static speckle noise in the final image after the coronagraph. The temporal evolution of the quasi-static wavefront error exhibits a linear power law, which can be used to first order to model quasi-static speckle evolution in high-contrast imaging instruments.

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Section: Introductionmentioning

confidence: 99%

Speckle temporal stability in XAO coronagraphic images

Martínez

Loose

Carpentier

et al. 2012

A&A

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“…Details on the coronograph and its performance are given in Beuzit et al (1997). We iteratively centered the star "behind" the mask.…”

Section: Program Goal and Observing Equipmentmentioning

confidence: 99%

A search for circumstellar dust disks with ADONIS

Schuetz¹,

Boehnhardt²,

Pantin

et al. 2004

A&A

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Abstract. We present results of a coronographic imaging search for circumstellar dust disks with the Adaptive Optics Near Infrared System (ADONIS) at the ESO 3.6 m telescope in La Silla (Chile). 22 candidate stars, known to be orbited by a planet or to show infrared excess radiation, were examined for circumstellar material. In the PSF-subtracted images no clear disk was found. We further determine the detection sensitivities and outline how remaining atmospheric fluctuations still can hamper adaptive optics observations.

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“…The interest in stellar coronagraphy is relatively recent (Bonneau et al 1975;Smith & Terrile 1984;Malbet 1996;Beuzit et al 1997;Mouillet et al 1997), and nowadays mainly stimulated by the exoplanets searches. The direct imaging of an exoplanet is the most exciting objective for high contrast imaging techniques: it will provide valuable information such as its mass (removing the ambiguity due to the radial velocities technique), its albedo and its atmosphere chemical composition if spectral information can be obtained.…”

Section: Introductionmentioning

confidence: 99%

Stellar coronagraphy with prolate apodized circular apertures

Soummer¹,

Aime²,

Falloon³

2003

A&A

154

188

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Abstract. This paper generalizes to circular apertures the theoretical study of stellar coronagraphy with prolate apodized rectangular entrance apertures of Aime et al. (2002). The main difference between the two studies is that circular prolate spheroidal functions are used for a circular aperture instead of linear prolate spheroidal functions for rectangular apertures. Owing to the radial property of the problem, the solution to the general equation for coronagraphy is solved using a Hankel transform instead of a product of Fourier transforms in the rectangular case. This new theoretical study permits a better understanding of coronagraphy, stressing the importance of entrance pupil apodization. A comparison with the classical unapodized Lyot technique is performed: a typical gain of 10 4 to 10 6 can be obtained theoretically with this technique. Circular and rectangular apertures give overall comparable results: a total extinction of the star light is obtained for Roddier & Roddier's phase mask technique whilst optimal starlight rejections are obtained with a Lyot opaque mask. A precise comparison between a circular aperture and a square aperture of same surface favors the use of a circular aperture for detection of extrasolar planets.

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A stellar coronograph for the COME-ON-PLUS adaptive optics system

Cited by 33 publications

References 6 publications

Speckle temporal stability in XAO coronagraphic images

Speckle temporal stability in XAO coronagraphic images

A search for circumstellar dust disks with ADONIS

Stellar coronagraphy with prolate apodized circular apertures

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