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  2. Fresnel diffraction - Wikipedia

    en.wikipedia.org/wiki/Fresnel_diffraction

    Fresnel diffraction of circular aperture, plotted with Lommel functions. This is the Fresnel diffraction integral; it means that, if the Fresnel approximation is valid, the propagating field is a spherical wave, originating at the aperture and moving along z. The integral modulates the amplitude and phase of the spherical wave.

  3. Near and far field - Wikipedia

    en.wikipedia.org/wiki/Near_and_far_field

    Differences between Fraunhofer diffraction and Fresnel diffraction. The near field itself is further divided into the reactive near field and the radiative near field. The reactive and radiative near-field designations are also a function of wavelength (or distance). However, these boundary regions are a fraction of one wavelength within the ...

  4. Fresnel number - Wikipedia

    en.wikipedia.org/wiki/Fresnel_number

    The Fresnel number is a useful concept in physical optics. The Fresnel number establishes a coarse criterion to define the near and far field approximations. Essentially, if Fresnel number is small – less than roughly 1 – the beam is said to be in the far field. If Fresnel number is larger than 1, the beam is said to be near field. However ...

  5. Fraunhofer diffraction - Wikipedia

    en.wikipedia.org/wiki/Fraunhofer_diffraction

    The Fraunhofer diffraction pattern is shown in the image together with a plot of the intensity vs. angle θ. [10] The pattern has maximum intensity at θ = 0, and a series of peaks of decreasing intensity. Most of the diffracted light falls between the first minima. The angle, α, subtended by these two minima is given by: [11]

  6. Diffraction from slits - Wikipedia

    en.wikipedia.org/wiki/Diffraction_from_slits

    The result is the Fraunhofer approximation, which is only valid very far away from the object + + Depending on the size of the diffraction object, the distance to the object and the wavelength of the wave, the Fresnel approximation, the Fraunhofer approximation or neither approximation may be valid. As the distance between the measured point of ...

  7. Electron diffraction - Wikipedia

    en.wikipedia.org/wiki/Electron_diffraction

    Close to an aperture or atoms, often called the "sample", the electron wave would be described in terms of near field or Fresnel diffraction. [12]: Chpt 7-8 This has relevance for imaging within electron microscopes, [1]: Chpt 3 [2]: Chpt 3-4 whereas electron diffraction patterns are measured far from the sample, which is described as far-field or Fraunhofer diffraction. [12]:

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  9. Fraunhofer diffraction equation - Wikipedia

    en.wikipedia.org/wiki/Fraunhofer_diffraction...

    The Fraunhofer diffraction equation is an approximation which can be applied when the diffracted wave is observed in the far field, and also when a lens is used to focus the diffracted light; in many instances, a simple analytical solution is available to the Fraunhofer equation – several of these are derived below.