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光行天下 -> 光學設(shè)計及經(jīng)驗 -> The size of Airy disk [點此返回論壇查看本帖完整版本]

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yazhuge

2008-07-12 09:25

The size of Airy disk

The central spot in the diffraction pattern of the image of a star at the focus of a telescope, named after George Airy. It is surrounded by several fine diffraction rings like the rings around the bull抯-eye of a target. The size of the Airy disk, given approximately in radians by 1.22 times the wavelength of light times the focal ratio, is the same for all telescopes of a given size and is less in instruments of larger aperture. (It is one of the quirks of astronomy that bigger telescopes produce smaller images of stars.) In practice, however, atmospheric turbulence, unless compensated for, results in a false disk that is larger than the Airy disk.