Living reference work entry
Coronagraphy designates the group of optical techniques that aim at suppressing or reducing the halo of light that surrounds the image of a star, in order to detect faint structures like a circumstellar disk or companions, especially exoplanets. It was invented in 1930 by the French astronomer Bernard Lyot (Fig. 1) to study the Sun’s corona, the extremely faint emission from the region around the Sun, at times other than during a solar eclipse. The coronagraph is in its simplest form an occulting disk in the focal plane of a telescope combined with a mask in a plane optically conjugated to the entrance aperture, so that the image of the solar disk is blocked and the stray light reduced by a large factor. Since then, the term has been kept for research in areas other than the solar corona and designates now any optical system able to block as much as possible the glare of a star to allow detection of companions or disk structures in its immediate vicinity.
KeywordsFocal Plane Adaptive Optic Extrasolar Planet Entrance Aperture Deformable Mirror
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References and Further Reading
- Rouan D, Baudrand J, Boccaletti A, Baudoz P, Mawet D, Riaud P (2007) The four quadrant phase mask coronagraph and its avatars. CR Phys 8Google Scholar
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