Stellar coronagraphy with prolate apodized circular apertures

Soummer, Rémi; Aime, Claude; Falloon, Peter E.

doi:10.1051/0004-6361:20021573

Cited by 154 publications

(189 citation statements)

References 22 publications

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“…Since the invention of the stellar Lyot coronagraph (Lyot 1939), there has been impressive progress in the field leading to a wealth of different coronagraphs that can be divided into different families. In particular, the Apodized Pupil Lyot Coronagraph (APLC) (Aime et al 2002;Soummer et al 2003a) appears to be well suited to ELTs and has been studied theoretically (Soummer 2005;Martinez et al 2007). The APLC features amplitude apodization in the entrance aperture for reducing diffraction, and a small Lyot mask in the focal plane.…”

Section: Introductionmentioning

confidence: 99%

Design, analysis, and testing of a microdot apodizer for the Apodized Pupil Lyot Coronagraph

Martínez

Dorrer

Carpentier³

et al. 2008

A&A

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Context. Coronagraphic techniques are required for detecting exoplanets with future Extremely Large Telescopes. One concept, the Apodized Pupil Lyot Coronagraph (APLC), combines an apodizer in the entrance aperture with a Lyot opaque mask in the focal plane. This paper presents the manufacturing and testing of a microdots apodizer optimized for the near IR. Aims. We attempt to demonstrate the feasibility and performance of binary apodizers for the APLC. This study is also relevant to coronagraph using amplitude pupil apodization. Methods. A binary apodizer was designed using a halftone-dot process, where the binary array of pixels with either 0% or 100% transmission was calculated to fit the required continuous transmission, i.e. local transmission control was obtained by varying the relative density of the opaque and transparent pixels. An error-diffusion algorithm was used to optimize the distribution of pixels that approximated the required field transmission. The prototype was tested with a coronagraphic setup in the near IR. Results. The transmission profile of the prototype agrees with the theoretical shape to within 3% and is achromatic. The observed apodized and coronagraphic images are consistent with theory. However, binary apodizers introduce high frequency noise that is a function of the pixel size. Numerical simulations were used to specify pixel size and minimize this effect, and validated by experiment. Conclusions. This paper demonstrates that binary apodizers are well suited for use in high-contrast imaging coronagraphs. The correct choice of pixel size is important and must be addressed by considering the scientific field of view.

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Section: Introductionmentioning

confidence: 99%

Design, analysis, and testing of a microdot apodizer for the Apodized Pupil Lyot Coronagraph

Martínez

Dorrer

Carpentier³

et al. 2008

A&A

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“…(Aime et al 2002;Soummer et al 2003). Unfortunately, a large fraction of the light is absorbed by the apodization mask.…”

Section: Introductionmentioning

confidence: 99%

Extreme coronagraphy with an adaptive hologram

Ricci¹,

Coroller²,

Labeyrie³

2009

A&A

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Aims. We present a solution to improve the performance of coronagraphs for the detection of exo-planets. Methods. We simulate numerically several kinds of coronagraphic systems, with the aim of evaluating the gain obtained with an adaptive hologram. Results. The detection limit in flux ratio between a star and a planet (F s /F p ) observed with an apodized Lyot coronagraph characterized by wavefront bumpiness imperfections of λ/20 (resp. λ/100) turns out to be increased by a factor of 10 3.4 (resp. 10 5.1 ) when equipped with a hologram. Conclusions. This technique could provide direct imaging of an exo-Earth at a distance of 11 parsec with a 6.5 m space telescope such as the JWST with the optical quality of the HST.

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“…Some candidates among the possible apodization profiles are the spheroidal prolate functions (Slepian 1965) that, as was well described in Frieden (1971), maximally concentrate in the mean square sense the light in the diffraction central spot. The properties of the spheroidal prolate functions make them very interesting for the Lyot coronagraph, as was pointed out in several papers (Aime et al 2002;Soummer et al 2003;Soummer 2005).…”

Section: Discussionmentioning

confidence: 93%

Reducing star leakage with a nuller coronagraph

Aimé

Rabbia

Carlotti

et al. 2011

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Aims. Our objective is to test the improvement of the detection capabilities of a nuller coronagraph when it is coupled to an apodizer. We call this instrument an apodized nuller coronagraph (ANC). Methods. With the usual Fourier optics formalism we first derive the analytical expression of the intensity distribution for an off-axis point-like source in the aperture and the focal plane of an ANC. Then the star leakage is obtained by integration of this response over the angular extension of the star. In this process are included the star's angular diameter, the apodization strength and the diameter of the telescope. Eventually we consider an application to the specific case of Sonine apodization. Results. From this analytical approach we obtain expressions of the contrast and signal-to-noise ratio for the direct detection of an exoplanet. These expressions involving instrumental parameters allow one to optimize the required minimum telescope's diameter and apodization strength with respect to the detection of a given target in spite of star leakage. We show that the direct detection of an exoplanet in a solar-like system can be obtained with a nuller coronagraph as soon as the aperture is sufficiently apodized, although the energy throughput of the system is reduced. For a system at 10 pc, an 8-m class telescope appears necessary to detect an exo-Earth, while no larger than a 2-m class telescope is required for an exo-Jupiter.

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Stellar coronagraphy with prolate apodized circular apertures

Cited by 154 publications

References 22 publications

Design, analysis, and testing of a microdot apodizer for the Apodized Pupil Lyot Coronagraph

Design, analysis, and testing of a microdot apodizer for the Apodized Pupil Lyot Coronagraph

Extreme coronagraphy with an adaptive hologram

Reducing star leakage with a nuller coronagraph

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