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- Beam_divergence abstract "The beam divergence of an electromagnetic beam is an angular measure of the increase in beam diameter or radius with distance from the optical aperture or antenna aperture from which the electromagnetic beam emerges. The term is relevant only in the "far field", away from any focus of the beam. Practically speaking, however, the far field can commence physically close to the radiating aperture, depending on aperture diameter and the operating wavelength.Beam divergence is often used to characterize electromagnetic beams in the optical regime, for cases in which the aperture from which the beam emerges is very large with respect to the wavelength. That said, it is also used in the Radio Frequency (RF) regime for cases in which the antenna is operating in the so-called optical region and is likewise very large relative to a wavelength.Beam divergence usually refers to a beam of circular cross section, but not necessarily so. A beam may, for example, have an elliptical cross section, in which case the orientation of the beam divergence must be specified, for example with respect to the major or minor axis of the elliptical cross section.The divergence of a beam can be calculated if one knows the beam diameter at two separate points (Di, Df), and the distance (l) between these points. The beam divergence, , is given by If the beam has been collimated using a lens or other focusing element, the divergence expected can be calculated from two parameters: the diameter, , of the narrowest point on the beam before the lens, and the focal length of the lens, . The divergence is then given by Like all electromagnetic beams, lasers are subject to divergence, which is measured in milliradians (mrad) or degrees. For many applications, a lower-divergence beam is preferable. Neglecting divergence due to poor beam quality, the divergence of a laser beam is proportional to its wavelength and inversely proportional to the diameter of the beam at its narrowest point. For example, an ultraviolet laser that emits at a wavelength of 308 nm will have a lower divergence than an infrared laser at 808 nm, if both have the same minimum beam diameter. The divergence of good-quality laser beams is modeled using the mathematics of Gaussian beams.Gaussian laser beams are said to be diffraction limited when their radial beam divergence is close to the minimum possible value, which is given bywhere is the laser wavelength and is the radius of the beam at its narrowest point, which is called the "beam waist". This type of beam divergence is observed from optimized laser cavities. Information on the diffraction-limited divergence of a coherent beam is inherently given by the N-slit interferometric equation.".
- Beam_divergence wikiPageExternalLink l1c02s02.html.
- Beam_divergence wikiPageExternalLink calculators.
- Beam_divergence wikiPageExternalLink diverge.html.
- Beam_divergence wikiPageID "40781".
- Beam_divergence wikiPageRevisionID "576135666".
- Beam_divergence hasPhotoCollection Beam_divergence.
- Beam_divergence subject Category:Antennas_(radio).
- Beam_divergence subject Category:Optics.
- Beam_divergence type BodyPart105220461.
- Beam_divergence type Eye105311054.
- Beam_divergence type Optics.
- Beam_divergence type Organ105297523.
- Beam_divergence type Part109385911.
- Beam_divergence type PhysicalEntity100001930.
- Beam_divergence type SenseOrgan105299178.
- Beam_divergence type Thing100002452.
- Beam_divergence comment "The beam divergence of an electromagnetic beam is an angular measure of the increase in beam diameter or radius with distance from the optical aperture or antenna aperture from which the electromagnetic beam emerges. The term is relevant only in the "far field", away from any focus of the beam.".
- Beam_divergence label "Beam divergence".
- Beam_divergence label "Convergentie en divergentie".
- Beam_divergence label "Divergencia (haz)".
- Beam_divergence label "Divergenz (Optik)".
- Beam_divergence sameAs Divergenz_(Optik).
- Beam_divergence sameAs Divergencia_(haz).
- Beam_divergence sameAs Convergentie_en_divergentie.
- Beam_divergence sameAs m.0b553.
- Beam_divergence sameAs Q1230543.
- Beam_divergence sameAs Q1230543.
- Beam_divergence sameAs Beam_divergence.
- Beam_divergence wasDerivedFrom Beam_divergence?oldid=576135666.
- Beam_divergence isPrimaryTopicOf Beam_divergence.