Total coronagraphic extinction of rectangular apertures using linear prolate apodizations

Aime, Claude; Soummer, Rémi; Ferrari, A.

doi:10.1051/0004-6361:20020419

Cited by 112 publications

(151 citation statements)

References 23 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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“…Using a small value of ψ and a telescope of large diameter, ARC can in principle detect an exo-Earth, a performance that seems difficult to envision with coronagraphs using phase masks such as those of Roddier & Roddier (1997), Rouan et al (2000), and Aime et al (2002), which are very efficient for an on-axis point source but strongly sensitive to star leakage. Coronagraphs using pupil or focal plane apodization, such as those of Soummer et al (2003) and Kuchner & Traub (2002), will be less sensitive to leakage with the drawback of a lower rejection or transmission efficiency.…”

Section: Resultsmentioning

confidence: 99%

ARC: an Achromatic Rotation-shearing Coronagraph

Aime¹,

Ricort²,

Carlotti

et al. 2010

A&A

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Context. Because of the larger size of future telescopes, the star leakage effect due to the finite diameter of the stars will become a major problem for coronagraphs with very small inner working angles (IWA). Aims. To reduce this star leakage, we propose a new instrumental concept, the Achromatic Rotation-shearing Coronagraph (ARC), that provides a variable IWA that is easily tunable to ensure the observation of Solar-like systems with an extremely large telescope. Methods. The ARC belongs to the nuller class of coronagraphs. It takes advantage of the achromatic dark output of a Mach-Zehnder interferometer (MZI). Field rotators set in the arms of the MZI rotate the π-phase shifted images of the MZI by an angle ψ. An on-axis point source (the star) is nulled as twin-images of an off-axis point source (the planet) are formed. For ψ = π, the ARC is equivalent to the achromatic interfero-coronagraph. For small ψ, the twin images of the off-axis source are formed close to each another, and eventually nulled if too close. In this way, the ARC can get rid of star leakage while optimizing the transmission of the planet. We describe the compensation of polarization effects induced by field rotators. An application to diluted apertures is shortly presented. Results. We perform the mathematical analysis of the technique using Cartesian and polar coordinates, and assuming that the system is optically perfect. Analytic expressions are given for the leakage in both the focal and aperture planes. Simplified expressions for the contrast and signal-to-noise ratio (SNR) in the focal plane are given for a circular aperture, explicitly showing that the level of star leakage decreases as sin 2 (ψ/2), while the SNR increases as the inverse of sin(ψ/2). Conclusions. The ARC is appropriate for the detection of exoplanets and is not intended to provide images of the environment of stars.

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Total coronagraphic extinction of rectangular apertures using linear prolate apodizations

Cited by 112 publications

References 23 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

ARC: an Achromatic Rotation-shearing Coronagraph

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