An Etymological Dictionary of Astronomy and Astrophysics
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فرهنگ ریشه شناختی اخترشناسی-اخترفیزیک

M. Heydari-Malayeri    -    Paris Observatory

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Number of Results: 5 Search : distortion
barrel distortion
  چولگی ِ چلیکی   
cowlegi-ye celiki (#)

Fr.: distortion en barillet   

A defect in an optical system in which magnification decreases with distance from the optical axis, whereby the image of a square appears barrel-shaped. Opposite of → pincushion distortion.

Barrel, M.E. barel, from O.Fr. baril; → distortion.

Cowlegi, → distortion; celiki, relating to celik "barrel".

distortion
  چولگی، چولش   
cowlegi (#), cowleš

Fr.: distorsion, déformation   

1) Extent to which a system, optical, acoustic, or electronic, fails to reproduce accurately at its output the characteristics of the input.
2) Optics: An optical imperfection caused by a → lens or → system of lenses which results in → magnification differences between different points on the → image. The points on the → object are misplaced in the image relative to the → center of the → field. See also → barrel distortion; → pincushion distortion.

Verbal noun of → distort.

pincushion distortion
  چولگی ِ بالشتکی   
cowlegi-ye bâleštaki

Fr.: distorsion en coussinet   

An → aberration of a → lens  → system in which → magnification increases with → distance from the → optical axis, whereby → horizontal and → vertical lines bend inward toward the → center of the → field. Opposite of → barrel distortion.

Pincushion, from pin, from M.E. pinne, O.E. pinn "peg;" cf. D. pin, Ger. Pinne; perhaps from L. pinna "feather, quill" + cushion, M.E. cuisshin, O.Fr. coissin (Fr. coussin) a variant of V.L. *coxinum, either from L. coxa "hip, thigh," or from L. culcita "mattress;" → distortion.

Cowlegi, → distortion; bâleštaki, adj. of bâleštak, diminutive of bâlešt, variant bâleš "cushion, pillow," Mid.Pers. bâlišn, bâlên "cushion, pillow;" Av. barəiš- "pillow, cushion;" cf. Skt. barhis- "straw, a bed or layer of kusa grass strewed over the sacrificial ground."

redshift space distortion
  چولگی ِ فضای ِ سرخ-کیب   
cowlegi-ye fazâ-ye sorx-kib

Fr.: distorsion dûe aux vitesses particulières sur la ligne de visée   

The distortion observed in → redshift space of → galaxy clusters caused by peculiar velocities of the members (→ peculiar velocity). In a perfectly homogeneous → Friedmann-Lemaitre Universe the redshifts would accurately measure radial distances from the observer, and the mapping from real space to redshift space would simply be an identity. In an inhomogeneous Universe the peculiar velocities associated with any inhomogeneous structure will introduce a distortion in this mapping (N. Kaiser, 1987, MNRAS 227, 1). See also: → fingers of God, → Kaiser effect.

redshift; → space; → distortion;.

wavefront distortion
  چولگی ِ پیشان ِ موج   
cowlegi-ye pišân-e mowj

Fr.: distortion de front d'onde   

The disruption of the spherical shape of a wavefront due to atmospheric turbulence which makes the adjacent points in the wavefront out of phase.

wavefront; → distortion.