Fraunhofer diffraction occurs in the far-field region, where light waves are treated as plane waves. This simplifies calculations and allows for the use of Fourier transforms to analyze diffraction patterns. The conditions for Fraunhofer diffraction include plane wave incidence and large observation distances.
The diffraction pattern depends on the aperture's shape and size. Rectangular apertures produce sinc functions, while circular apertures create Airy patterns. Increasing aperture size improves resolution and brightness but adds more secondary maxima to the diffraction pattern.
Fraunhofer Diffraction: Far-Field Patterns
Conditions for Fraunhofer diffraction
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27.2 Huygens’s Principle: Diffraction – College Physics View original
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Incident light must be a plane wave or spherical wave from a point source at infinity enables simplified mathematical analysis
Diffracted light observed at a large distance from the aperture (far-field region) allows for the use of Fourier transform in calculations
Aperture size much larger than the wavelength of incident light ensures the validity of scalar diffraction theory
In the far-field region, diffraction pattern independent of distance between aperture and observation plane simplifies calculations
Fraunhofer diffraction relevant in far-field region allows analysis of diffraction pattern using Fourier transform of aperture function (telescopes, microscopes)
Mathematical derivation of diffraction patterns
Complex amplitude of diffracted light in far-field region proportional to Fourier transform of aperture function U(x,y) enables mathematical analysis