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- Spherical_aberration abstract "Not to be confused with barrel distortion, in which the image appears to be warped onto a sphere.Spherical aberration is an optical effect observed in an optical device (lens, mirror, etc.) that occurs due to the increased refraction of light rays when they strike a lens or a reflection of light rays when they strike a mirror near its edge, in comparison with those that strike nearer the centre. It signifies a deviation of the device from the norm, i.e., it results in an imperfection of the produced image.A spherical lens has an aplanatic point (i.e., no spherical aberration) only at a radius that equals the radius of the sphere divided by the index of refraction of the lens material. A typical value of refractive index for crown glass is 1.5, (See list) which indicates that only about 43% of the area (67% of diameter) of a spherical lens is useful. It is often considered to be an imperfection of telescopes and other instruments which makes their focusing less than ideal due to the spherical shape of lenses and mirrors. This is an important effect, because spherical shapes are much easier to produce than aspherical ones. In many cases, it is cheaper to use multiple spherical elements to compensate for spherical aberration than it is to use a single aspheric lens."Positive" spherical aberration means peripheral rays are bent too much. "Negative" spherical aberration means peripheral rays are not bent enough.The effect is proportional to the fourth power of the diameter and inversely proportional to the third power of the focal length, so it is much more pronounced at short focal ratios, i.e., "fast" lenses. In lens systems, the effect can be minimized using special combinations of convex and concave lenses, as well as using aspheric lenses.For simple designs one can sometimes calculate parameters that minimize spherical aberration. For example, in a design consisting of a single lens with spherical surfaces and a given object distance o, image distance i, and refractive index n, one can minimize spherical aberration by adjusting the radii of curvature and of the front and back surfaces of the lens such that.For small telescopes using spherical mirrors with focal ratios shorter than f/10, light from a distant point source (such as a star) is not all focused at the same point. Particularly, light striking the inner part of the mirror focuses farther from the mirror than light striking the outer part. As a result the image cannot be focused as sharply as if the aberration were not present. Because of spherical aberration, telescopes shorter than f/10 are usually made with non-spherical mirrors or with correcting lenses.".
- Spherical_aberration thumbnail Spherical_aberration_2.svg?width=300.
- Spherical_aberration wikiPageExternalLink spherical.html.
- Spherical_aberration wikiPageExternalLink spherical1.htm.
- Spherical_aberration wikiPageID "214102".
- Spherical_aberration wikiPageRevisionID "591435285".
- Spherical_aberration hasPhotoCollection Spherical_aberration.
- Spherical_aberration subject Category:Geometrical_optics.
- Spherical_aberration subject Category:Optics.
- Spherical_aberration comment "Not to be confused with barrel distortion, in which the image appears to be warped onto a sphere.Spherical aberration is an optical effect observed in an optical device (lens, mirror, etc.) that occurs due to the increased refraction of light rays when they strike a lens or a reflection of light rays when they strike a mirror near its edge, in comparison with those that strike nearer the centre.".
- Spherical_aberration label "Aberración esférica".
- Spherical_aberration label "Aberracja sferyczna".
- Spherical_aberration label "Aberration géométrique".
- Spherical_aberration label "Aberrazione sferica".
- Spherical_aberration label "Aberração esférica".
- Spherical_aberration label "Sferische aberratie".
- Spherical_aberration label "Spherical aberration".
- Spherical_aberration label "Сферическая аберрация".
- Spherical_aberration label "زيغ كروي".
- Spherical_aberration label "球面像差".
- Spherical_aberration sameAs Sférická_aberace.
- Spherical_aberration sameAs Σφάλμα_σφαιρικής_εκτροπής.
- Spherical_aberration sameAs Aberración_esférica.
- Spherical_aberration sameAs Aberrazio_esferiko.
- Spherical_aberration sameAs Aberration_géométrique.
- Spherical_aberration sameAs Aberrazione_sferica.
- Spherical_aberration sameAs 구면수차.
- Spherical_aberration sameAs Sferische_aberratie.
- Spherical_aberration sameAs Aberracja_sferyczna.
- Spherical_aberration sameAs Aberração_esférica.
- Spherical_aberration sameAs m.01fc68.
- Spherical_aberration sameAs Q2913798.
- Spherical_aberration sameAs Q2913798.
- Spherical_aberration wasDerivedFrom Spherical_aberration?oldid=591435285.
- Spherical_aberration depiction Spherical_aberration_2.svg.
- Spherical_aberration isPrimaryTopicOf Spherical_aberration.
