Fraunhofer diffraction
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Fraunhofer diffraction is diffraction of light through an aperture for small values of the Fresnel number, F<<1.
If a light source and an observation screen are effectively far enough from a diffraction aperture (for example a slit), then the wavefronts arriving at the aperture and the screen can be considered to be collimated, or plane. Fraunhofer, or far-field, diffraction occurs when this is not the case and the curvature of the incident wavefronts is taken into account.
In far-field diffraction, if the observation screen is moved relative to the aperture, the diffraction pattern produced changes uniformly in size. This is not the case in near-field diffraction, where the diffraction pattern changes both in size and shape.
External links
- Fraunhofer diffraction (http://scienceworld.wolfram.com/physics/FraunhoferDiffraction.html) on ScienceWorld
- Fraunhofer diffraction (http://hyperphysics.phy-astr.gsu.edu/hbase/phyopt/fraunhofcon.html) on HyperPhysicsTemplate:Physics-stub