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- Coma_(optics) abstract "In optics (especially telescopes), the coma, or comatic aberration, in an optical system refers to aberration inherent to certain optical designs or due to imperfection in the lens or other components that results in off-axis point sources such as stars appearing distorted, appearing to have a tail (coma) like a comet. Specifically, coma is defined as a variation in magnification over the entrance pupil. In refractive or diffractive optical systems, especially those imaging a wide spectral range, coma can be a function of wavelength, in which case it is a form of chromatic aberration.Coma is an inherent property of telescopes using parabolic mirrors. Unlike a spherical mirror, a bundle of parallel rays parallel to the optical axis will be perfectly focused to a point (the mirror is free of spherical aberration), no matter where they strike the mirror. However, this is only true if the rays are parallel to the axis of the parabola. When the incoming rays strike the mirror at an angle, individual rays are not reflected to the same point. When looking at a point that is not perfectly aligned with the optical axis, some of the incoming light from that point will strike the mirror at an angle. This results in an image that is not in the center of the field looking wedge-shaped. The further off-axis (or the greater the angle subtended by the point with the optical axis), the worse this effect is. This causes stars to appear to have a cometary coma, hence the name.[1]Schemes to reduce spherical aberration without introducing coma include Schmidt, Maksutov, ACF and Ritchey-Chrétien optical systems. Correction lenses for Newtonian reflectors have been designed which reduce coma in telescopes below f/6. These work by means of a dual lens system of a plano-convex and a plano-concave lens fitted into an eyepiece adaptor which superficially resembles a Barlow lens.Coma of a single lens or a system of lenses can be minimized (and in some cases eliminated) by choosing the curvature of the lens surfaces to match the application. Lenses in which both spherical aberration and coma are minimized at a single wavelength are called bestform or aplanatic lenses.Vertical coma is the most common higher-order aberration in the eyes of patients with keratoconus. Coma is also a common temporary symptom of corneal injuries or abrasions, in which case the visual defect gradually resolves as the cornea heals.".
- Coma_(optics) thumbnail Lens-coma.svg?width=300.
- Coma_(optics) wikiPageExternalLink about_coma.html.
- Coma_(optics) wikiPageExternalLink watch?v=EXmaY2txEBo.
- Coma_(optics) wikiPageID "583405".
- Coma_(optics) wikiPageLength "4796".
- Coma_(optics) wikiPageOutDegree "30".
- Coma_(optics) wikiPageRevisionID "667418192".
- Coma_(optics) wikiPageWikiLink Barlow_lens.
- Coma_(optics) wikiPageWikiLink Category:Optics.
- Coma_(optics) wikiPageWikiLink Chromatic_aberration.
- Coma_(optics) wikiPageWikiLink Coma_(cometary).
- Coma_(optics) wikiPageWikiLink Comet.
- Coma_(optics) wikiPageWikiLink Curvature.
- Coma_(optics) wikiPageWikiLink Curved_mirror.
- Coma_(optics) wikiPageWikiLink Diffraction.
- Coma_(optics) wikiPageWikiLink Entrance_pupil.
- Coma_(optics) wikiPageWikiLink Keratoconus.
- Coma_(optics) wikiPageWikiLink Lens_(optics).
- Coma_(optics) wikiPageWikiLink Magnification.
- Coma_(optics) wikiPageWikiLink Maksutov_telescope.
- Coma_(optics) wikiPageWikiLink Meade_Instruments.
- Coma_(optics) wikiPageWikiLink Newtonian_telescope.
- Coma_(optics) wikiPageWikiLink Optical_aberration.
- Coma_(optics) wikiPageWikiLink Optics.
- Coma_(optics) wikiPageWikiLink Parabolic_reflector.
- Coma_(optics) wikiPageWikiLink Point_source.
- Coma_(optics) wikiPageWikiLink Refraction.
- Coma_(optics) wikiPageWikiLink Ritchey–Chrétien_telescope.
- Coma_(optics) wikiPageWikiLink Schmidt_camera.
- Coma_(optics) wikiPageWikiLink Spherical_aberration.
- Coma_(optics) wikiPageWikiLink Telescope.
- Coma_(optics) wikiPageWikiLink Wavelength.
- Coma_(optics) wikiPageWikiLink Zernike_polynomials.
- Coma_(optics) wikiPageWikiLink File:Baader_Rowe_Coma_Corrector_Comparison.jpg.
- Coma_(optics) wikiPageWikiLink File:Lens-coma.svg.
- Coma_(optics) wikiPageWikiLinkText "Coma (optics)".
- Coma_(optics) wikiPageWikiLinkText "Coma".
- Coma_(optics) wikiPageWikiLinkText "Vertical coma".
- Coma_(optics) wikiPageWikiLinkText "coma".
- Coma_(optics) wikiPageWikiLinkText "comatic aberration".
- Coma_(optics) wikiPageUsesTemplate Template:Optical_aberration.
- Coma_(optics) wikiPageUsesTemplate Template:Reflist.
- Coma_(optics) subject Category:Optics.
- Coma_(optics) type Science.
- Coma_(optics) comment "In optics (especially telescopes), the coma, or comatic aberration, in an optical system refers to aberration inherent to certain optical designs or due to imperfection in the lens or other components that results in off-axis point sources such as stars appearing distorted, appearing to have a tail (coma) like a comet. Specifically, coma is defined as a variation in magnification over the entrance pupil.".
- Coma_(optics) label "Coma (optics)".
- Coma_(optics) sameAs Q1772448.
- Coma_(optics) sameAs Несиметрична_аберация.
- Coma_(optics) sameAs Coma_(òptica).
- Coma_(optics) sameAs Koma_(optik).
- Coma_(optics) sameAs Σφάλμα_κόμης.
- Coma_(optics) sameAs Coma_(óptica).
- Coma_(optics) sameAs کما_(نورشناسی).
- Coma_(optics) sameAs Koma.
- Coma_(optics) sameAs Coma_(optique).
- Coma_(optics) sameAs Coma_(ottica).
- Coma_(optics) sameAs コマ収差.
- Coma_(optics) sameAs 혜성형_수차.
- Coma_(optics) sameAs Coma_(optica).
- Coma_(optics) sameAs Koma_i_optikk.
- Coma_(optics) sameAs Koma_(optyka).
- Coma_(optics) sameAs Comëtta_(òtica).
- Coma_(optics) sameAs m.02sdnt.
- Coma_(optics) sameAs Кома_(оптика).
- Coma_(optics) sameAs Koma_(optika).
- Coma_(optics) sameAs Koma_(optik).
- Coma_(optics) sameAs Кома_(оптика).
- Coma_(optics) sameAs Q1772448.
- Coma_(optics) sameAs 彗形像差.
- Coma_(optics) wasDerivedFrom Coma_(optics)?oldid=667418192.
- Coma_(optics) depiction Lens-coma.svg.
- Coma_(optics) isPrimaryTopicOf Coma_(optics).