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Airy disk(air -ee) The bright disklike image of a point source of light, such as a star, as seen in an optical system with a circular aperture. The disk is formed by diffraction effects in the instrument and is surrounded by faint diffraction rings that are only seen under perfect conditions (see illustration). The disk diameter, first calculated by George Airy in 1834, is the factor limiting the angular resolution of the telescope.
Airy disk[¦er·ē ¦disk]
The bright, diffuse central spot of light formed by an optical system imaging a point source of light.