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  2. Bessel function - Wikipedia

    en.wikipedia.org/wiki/Bessel_function

    Bessel functions describe the radial part of vibrations of a circular membrane.. Bessel functions, named after Friedrich Bessel who was the first to systematically study them in 1824, [1] are canonical solutions y(x) of Bessel's differential equation + + = for an arbitrary complex number, which represents the order of the Bessel function.

  3. Sinc function - Wikipedia

    en.wikipedia.org/wiki/Sinc_function

    The sinc function for a non-Cartesian lattice (e.g., hexagonal lattice) is a function whose Fourier transform is the indicator function of the Brillouin zone of that lattice. For example, the sinc function for the hexagonal lattice is a function whose Fourier transform is the indicator function of the unit hexagon in the frequency space. For a ...

  4. Sombrero function - Wikipedia

    en.wikipedia.org/wiki/Sombrero_function

    Sombrero function 3D. A sombrero function (sometimes called besinc function or jinc function [1]) is the 2-dimensional polar coordinate analog of the sinc function, and is so-called because it is shaped like a sombrero hat. This function is frequently used in image processing. [2]

  5. Airy disk - Wikipedia

    en.wikipedia.org/wiki/Airy_disk

    where is the maximum intensity of the pattern at the Airy disc center, is the Bessel function of the first kind of order one, = / is the wavenumber, is the radius of the aperture, and is the angle of observation, i.e. the angle between the axis of the circular aperture and the line between aperture center and observation point.

  6. Ringing artifacts - Wikipedia

    en.wikipedia.org/wiki/Ringing_artifacts

    The sinc function, the impulse response for an ideal low-pass filter, illustrating ringing for an impulse. The Gibbs phenomenon, illustrating ringing for a step function.. By definition, ringing occurs when a non-oscillating input yields an oscillating output: formally, when an input signal which is monotonic on an interval has output response which is not monotonic.

  7. Bessel beam - Wikipedia

    en.wikipedia.org/wiki/Bessel_beam

    The mathematical function which describes a Bessel beam is a solution of Bessel's differential equation, which itself arises from separable solutions to Laplace's equation and the Helmholtz equation in cylindrical coordinates. The fundamental zero-order Bessel beam has an amplitude maximum at the origin, while a high-order Bessel beam (HOBB ...

  8. Point spread function - Wikipedia

    en.wikipedia.org/wiki/Point_spread_function

    The point spread function (PSF) describes the response of a focused optical imaging system to a point source or point object. A more general term for the PSF is the system's impulse response; the PSF is the impulse response or impulse response function (IRF) of a focused optical imaging system. The PSF in many contexts can be thought of as the ...

  9. Trigonometric integral - Wikipedia

    en.wikipedia.org/wiki/Trigonometric_integral

    Note that the integrand ⁡ is the sinc function, and also the zeroth spherical Bessel function. Since sinc is an even entire function (holomorphic over the entire complex plane), Si is entire, odd, and the integral in its definition can be taken along any path connecting the endpoints.