George Biddell Airy calculated the diffraction pattern produced by a circular aperture. His treatment explains why an unresolved star appears as a central bright region surrounded by rings even in an otherwise ideal optical telescope.
In modern notation, the first dark ring occurs at an angle approximately , where is the wavelength and the aperture diameter. Doubling the diameter halves this angular scale at fixed wavelength. The Airy disk thus connects the wave nature of light to the resolving power of an instrument; simply increasing magnification cannot remove the underlying diffraction pattern.[ref]
On the Diffraction of an Object-glass with Circular Aperture by George Biddell Airy. Original circular-aperture calculation and first dark-ring result; reproduced original in appendix, pp. 62–66 of annotated document
His name also appears in the Airy functions, another recurring mathematical tool in wave and differential-equation problems.
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Portrait of George Biddell Airy
. Cundall Downes & Co.; Smithsonian Institution Libraries / Dibner Library, via Flickr Commons. No known copyright restrictions (Flickr Commons; reviewed by FlickreviewR), via Wikimedia Commons. Source.
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