Editing Fraunhofer diffraction (section)

===Diffraction by a circular aperture===
[[File:Airy-pattern2.jpg|thumb|150px|right|Computer simulation of the Airy diffraction pattern]]The diffraction pattern given by a circular aperture is shown in the figure on the right.<ref>{{harvnb|Born|Wolf|1999|loc=Figure 8.12}}</ref> This is known as the [[Airy Disk|Airy diffraction pattern]]. It can be seen that most of the light is in the central disk. The angle subtended by this disk, known as the Airy disk, is
<math display="block"> \alpha \approx \frac {1.22 \lambda} {W}</math>
where {{math|''W''}} is the diameter of the aperture.

The Airy disk can be an important parameter in [[Angular resolution|limiting the ability]] of an imaging system to resolve closely located objects.