- Bessel beam
A Bessel beam is a field of
electromagnetic radiationwhose amplitude is described by a Bessel function. A true Bessel beam is non-diffractive. This means that as it propagates, it does not diffractand spread out; this is in contrast to the usual behavior of light, which spreads out after being focussed down to a small spot.
As with a
plane wavea true Bessel beam cannot be created, as it is unbounded and therefore requires an infinite amount of energy. [cite web|url=http://www.st-andrews.ac.uk/~atomtrap/Research/reconstruct.htm| author=Kishan Dholakia| coauthors= David McGloin, and Vene Garcés-Chávez| title=Optical micromanipulating using a self-reconstructing light beam| year=2002| accessdate=2007-02-06
See also cite journal|author=V. Garcés-Chávez| coauthors= D. McGloin, H. Melville, W. Sibbett and K. Dholakia| title=Simultaneous micromanipulation in multiple planes using a self-reconstructing light beam| journal=Nature| volume= 419| year=2002| url=http://sinclair.ece.uci.edu/Papers/Optics/Orbital%20angular%20momentum/Garces-Chavez%20Nature%20419%20pp145-148%202002%20(Simultaneous%20micromanipulation%20in%20multiple%20planes%20using%20a%20self-reconstructing%20light%20beam).pdf| accessdate=2007-02-06| doi=10.1038/nature01007| pages=145] Reasonably good approximations can be made, however, and these are important in many
opticalapplications because they exhibit little or no diffraction over a limited distance. Bessel beams are also "self-healing", meaning that the beam can be partially obstructed at one point, but will re-form at a point further down the beam axis.
These properties together make Bessel beams extremely useful to research in optical tweezing, as a narrow Bessel beam will maintain its required property of tight focus over a relatively long section of beam and even when partially occluded by the dielectric particles being tweezed.
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 equationand the Helmholtz equationin cylindrical coordinates.
Approximations to Bessel beams are made in practice by focusing a
Gaussian beamwith an axiconlens to generate a Bessel-Gauss beam.
Wikimedia Foundation. 2010.
Look at other dictionaries:
Bessel — may refer to: * Bessel beam * Bessel ellipsoid * Bessel function in mathematics * Bessel s inequality in mathematics * Bessel filter, a linear filter often used in audio crossover systems * Bessel (crater), a small lunar crater * Bessel transform … Wikipedia
Faisceau de Bessel — Un faisceau de Bessel est un champ de radiations électromagnétiques,,, acoustiques ou gravitationnelles dont l amplitude suit une fonction de Bessel de première espèce. Pour le faisceau de Bessel d ordre zéro, l amplitude est maximale à… … Wikipédia en Français
Gaussian beam — In optics, a Gaussian beam is a beam of electromagnetic radiation whose transverse electric field and intensity (irradiance) distributions are well approximated by Gaussian functions. Many lasers emit beams that approximate a Gaussian profile, in … Wikipedia
Tophat beam — In optics, a tophat (or top hat) beam is a laser beam with a near uniform fluence (energy density) within a circular disk. It is typically formed by diffractive optical elements from a Gaussian beam. Tophat beams are often used in industry, for… … Wikipedia
MV Bessel — Career Name: Sorrento (1925–28) Bessel (1928–45) Empire Coniston (1945–47) Birgitte Skou (1947–59) N Martini (1959–61) Nicolo Martini (1961–73) Owner: Robert M Sloman Jr (1925– … Wikipedia
Convolution for optical broad-beam responses in scattering media — Photon transport theories, such as the Monte Carlo method, are commonly used to model light propagation in tissue. The responses to a pencil beam incident on a scattering medium are referred to as Green’s functions or impulse responses. Photon… … Wikipedia
Optical tweezers — (originally called single beam gradient force trap ) are scientific instruments that use a highly focused laser beam to provide an attractive or repulsive force (typically on the order of piconewtons), depending on the refractive index mismatch… … Wikipedia
Mohammad Ataul Karim — Born May 4, 1953 (1953 05 04) (age 58) Sylhet, Bangladesh Citizenship Bangladesh / USA … Wikipedia
Laser — For other uses, see Laser (disambiguation). United States Air Force laser experiment … Wikipedia
Луч Бесселя — Диаграмма аксиконической линзы и получаемого луча Бесселя … Википедия