Bessel beam: Difference between revisions
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A '''Bessel beam''' is a beam of [[electromagnetic radiation]] whose [[intensity]] is described by a [[Bessel function]]. A true Bessel beam is non-diffractive. This means that as it propagates, it does not [[diffract]] and spread out; this is in contrast to the usual behavior of light, which spreads out after being focussed down to a small spot. A true Bessel beam cannot be created, because it would require an infinite amount of [[energy]]. Reasonably good approximations can be made, however, and these are important in many [[optical]] applications 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]]. |
A '''Bessel beam''' is a beam of [[electromagnetic radiation]] whose [[intensity]] is described by a [[Bessel function]]. A true Bessel beam is non-diffractive. This means that as it propagates, it does not [[diffract]] and spread out; this is in contrast to the usual behavior of light, which spreads out after being focussed down to a small spot. A true Bessel beam cannot be created, because it would require an infinite amount of [[energy]].<ref>{{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}}<br>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}}</ref> Reasonably good approximations can be made, however, and these are important in many [[optical]] applications 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]]. |
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These properties together make Bessel beams extremely useful to research in [[Optical Tweezers|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 [[occlusion|occluded]] by the dielectric particles being tweezed. |
These properties together make Bessel beams extremely useful to research in [[Optical Tweezers|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 [[occlusion|occluded]] by the dielectric particles being tweezed. |
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Revision as of 19:26, 6 February 2007
A Bessel beam is a beam of electromagnetic radiation whose intensity is described by a Bessel function. A true Bessel beam is non-diffractive. This means that as it propagates, it does not diffract and spread out; this is in contrast to the usual behavior of light, which spreads out after being focussed down to a small spot. A true Bessel beam cannot be created, because it would require an infinite amount of energy.[1] Reasonably good approximations can be made, however, and these are important in many optical applications 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 equation and the Helmholtz equation in cylindrical coordinates.
Bessel beams are made in practice by focusing a Gaussian beam with an axicon lens.
References
- ^ Kishan Dholakia (2002). "Optical micromanipulating using a self-reconstructing light beam". Retrieved 2007-02-06.
{{cite web}}: Unknown parameter|coauthors=ignored (|author=suggested) (help)
See also V. Garcés-Chávez (2002). "Simultaneous micromanipulation in multiple planes using a self-reconstructing light beam" (PDF). Nature. 419. Retrieved 2007-02-06.{{cite journal}}: Unknown parameter|coauthors=ignored (|author=suggested) (help)