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spherical aberration
spherical aberration A defect of mirrors and lenses in which rays of light parallel to but far from the optical axis are brought to a different focus from those close to the axis. Spherical aberration is seen in the images formed by spheroidal mirrors and by some lenses and eyepieces. A star image suffering from spherical aberration has no unique focus but instead has a least circle of confusion where the image is at its smallest. Beyond this point the image is a bright spot surrounded by a disk; inside it, the image is a ring darkening towards the centre. If rays from the edge of the mirror or lens come to a focus closer than those from its centre, the aberration is called undercorrected; in the opposite case it is overcorrected.
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"spherical aberration." A Dictionary of Astronomy. 1997. Encyclopedia.com. 30 May. 2012 <http://www.encyclopedia.com>. "spherical aberration." A Dictionary of Astronomy. 1997. Encyclopedia.com. (May 30, 2012). http://www.encyclopedia.com/doc/1O80-sphericalaberration.html "spherical aberration." A Dictionary of Astronomy. 1997. Retrieved May 30, 2012 from Encyclopedia.com: http://www.encyclopedia.com/doc/1O80-sphericalaberration.html |
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aberration, optical
aberration, optical An imperfection or error in the image produced by a lens, mirror, or optical system. There are six types of aberration: chromatic aberration, spherical aberration, coma (see Coma, Optical), field curvature, distortion, and astigmatism. Chromatic aberration is not present in images formed by mirrors. All can be corrected to a greater or lesser extent by suitable optical design.
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"aberration, optical." A Dictionary of Astronomy. 1997. Encyclopedia.com. 30 May. 2012 <http://www.encyclopedia.com>. "aberration, optical." A Dictionary of Astronomy. 1997. Encyclopedia.com. (May 30, 2012). http://www.encyclopedia.com/doc/1O80-aberrationoptical.html "aberration, optical." A Dictionary of Astronomy. 1997. Retrieved May 30, 2012 from Encyclopedia.com: http://www.encyclopedia.com/doc/1O80-aberrationoptical.html |
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spherical aberration
spherical aberration see aberration , in optics. |
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Cite this article
"spherical aberration." The Columbia Encyclopedia, 6th ed.. 2011. Encyclopedia.com. 30 May. 2012 <http://www.encyclopedia.com>. "spherical aberration." The Columbia Encyclopedia, 6th ed.. 2011. Encyclopedia.com. (May 30, 2012). http://www.encyclopedia.com/doc/1E1-X-spherica.html "spherical aberration." The Columbia Encyclopedia, 6th ed.. 2011. Retrieved May 30, 2012 from Encyclopedia.com: http://www.encyclopedia.com/doc/1E1-X-spherica.html |
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