Editing Fraunhofer diffraction (section)

===Diffraction by an aperture with a Gaussian profile===

[[Image:Exp squared function.svg|right|200px|thumb|Intensity of a plane wave diffracted through an aperture with a Gaussian profile]] The diffraction pattern obtained given by an aperture with a [[Gaussian function|Gaussian]] profile, for example, a photographic slide whose [[Transmittance|transmissivity]] has a Gaussian variation is also a Gaussian function. The form of the function is plotted on the right (above, for a tablet), and it can be seen that, unlike the diffraction patterns produced by rectangular or circular apertures, it has no secondary rings.<ref>{{harvnb|Hecht|2002|loc=Figure 11.33}}</ref> This technique can be used in a process called [[apodization]]—the aperture is covered by a Gaussian filter, giving a diffraction pattern with no secondary rings.

The output profile of a single mode laser beam may have a [[Gaussian beam|Gaussian]] intensity profile and the diffraction equation can be used to show that it maintains that profile however far away it propagates from the source.<ref>{{harvnb|Hecht|2002|loc=Figure 13.14}}</ref>