An Aragoscope is a telescope design based on diffraction around the edge of an occluding disc, named after French scientist
François Arago
Dominique François Jean Arago (), known simply as François Arago (; Catalan: , ; 26 February 17862 October 1853), was a French mathematician, physicist, astronomer, freemason, supporter of the Carbonari revolutionaries and politician.
Early l ...
.
Concept
The light diffracted around the edge of a perfectly circular occluder interferes constructively at the central axis, producing a bright spot known as the
Arago spot
In optics, the Arago spot, Poisson spot, or Fresnel spot is a bright point that appears at the center of a circular object's shadow due to Fresnel diffraction. This spot played an important role in the discovery of the wave nature of light and ...
. The resolution at that point would be equal to the resolution of a conventional lens with the same size as the occluder, although the light would be much less intense. On this basis it would be possible to create a telescope by placing a suitable disc in space accompanied by a separate telescope some distance away along its axis. This concept has been explored by NASA and received Phase One funding in June 2014 by the
NASA Innovative Advanced Concepts
The NASA Innovative Advanced Concepts (NIAC), formerly NASA Institute for Advanced Concepts (NIAC), is a NASA program for development of far reaching, long term advanced concepts by "creating breakthroughs, radically better or entirely new aerospa ...
(NIAC) program.
It is important to note that this is a very different approach from that taken by another NASA project, the
New Worlds Mission, which aims to use an occluder with "petals", otherwise known as a starshade, specifically designed to ''avoid'' diffraction onto the central axis.
See also
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Arago telescope
Arago telescope (''Lunette Arago'') is a 38 cm (15 inch) aperture refracting telescope at Paris Observatory, installed in 1857. François Arago, Francois Arago ordered this telescope from the telescope making firm Lebreours in 1839, and af ...
, a 38 cm (15 inch) refractor at Paris Observatory's east tower
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Zone plate
A zone plate is a device used to focus light or other things exhibiting wave character.G. W. Webb, I. V. Minin and O. V. Minin, “Variable Reference Phase in Diffractive Antennas”, ''IEEE Antennas and Propagation Magazine'', vol. 53, no. 2, ...
References
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Telescopes