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  2. 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 ...

  3. Augustin-Jean Fresnel - Wikipedia

    en.wikipedia.org/wiki/Augustin-Jean_Fresnel

    Augustin-Jean Fresnel [Note 1] (10 May 1788 – 14 July 1827) was a French civil engineer and physicist whose research in optics led to the almost unanimous acceptance of the wave theory of light, excluding any remnant of Newton's corpuscular theory, from the late 1830s [3] until the end of the 19th century.

  4. Fresnel zone - Wikipedia

    en.wikipedia.org/wiki/Fresnel_zone

    Fresnel zone: D is the distance between the transmitter and the receiver; r is the radius of the first Fresnel zone (n=1) at point P. P is d1 away from the transmitter, and d2 away from the receiver. The concept of Fresnel zone clearance may be used to analyze interference by obstacles near the path of a radio beam. The first zone must be kept ...

  5. Fresnel lens - Wikipedia

    en.wikipedia.org/wiki/Fresnel_lens

    The Fresnel lens reduces the amount of material required compared to a conventional lens by dividing the lens into a set of concentric annular sections. An ideal Fresnel lens would have an infinite number of sections. In each section, the overall thickness is decreased compared to an equivalent simple lens.

  6. Fresnel equations - Wikipedia

    en.wikipedia.org/wiki/Fresnel_equations

    The Fresnel equations (or Fresnel coefficients) describe the reflection and transmission of light (or electromagnetic radiation in general) when incident on an interface between different optical media.

  7. Fresnel diffraction - Wikipedia

    en.wikipedia.org/wiki/Fresnel_diffraction

    The near field can be specified by the Fresnel number, F, of the optical arrangement. When F ≪ 1 {\displaystyle F\ll 1} the diffracted wave is considered to be in the Fraunhofer field. However, the validity of the Fresnel diffraction integral is deduced by the approximations derived below.

  8. Zone plate - Wikipedia

    en.wikipedia.org/wiki/Zone_plate

    The result is that the effective f-number of a zone plate is lower than for the corresponding pinhole and the exposure time can be decreased. Common f-numbers for a pinhole camera range from f /150 to f /200 or higher, whereas zone plates are frequently f /40 and lower.

  9. Huygens–Fresnel principle - Wikipedia

    en.wikipedia.org/wiki/Huygens–Fresnel_principle

    The Huygens–Fresnel principle (named after Dutch physicist Christiaan Huygens and French physicist Augustin-Jean Fresnel) states that every point on a wavefront is itself the source of spherical wavelets, and the secondary wavelets emanating from different points mutually interfere. [1] The sum of these spherical wavelets forms a new wavefront.