diopter

dioptral, adj.
/duy op"teuhr/, n.
1. Optics. a unit of measure of the refractive power of a lens, having the dimension of the reciprocal of length and a unit equal to the reciprocal of one meter. Abbr.: D
2. an instrument, invented by Hipparchus, to measure the apparent diameter of the sun or moon or to estimate the size or elevation of distant objects.
Also, esp. Brit., dioptre.
[1585-95; < L dioptra < Gk: instrument for measuring height or levels, equiv. to di- DI-3 + op- (for ópsesthai to see) + -tra n. suffix of means]

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optics
      in optics, unit of magnifying power of a lens or lens system. Because the power of a lens is proportional to unity (one) divided by the focal length (see lens), the power of a lens in diopters is numerically equal to 1 m divided by the focal length in metres. The algebraic sign of the magnifying power indicates whether the lens causes an incident pencil of parallel light rays to converge or to diverge. Thus, a diverging lens having a focal length of 1 m has a power of -1 diopter, and a converging lens of focal length 0.5 m has a power of two diopters. The power of a combination of two or more thin lenses in contact is equal to the sum of the powers of the individual lenses. For example, a lens of -10 diopters combined with a lens of 30 diopters gives a converging lens of 20 diopters (of 5 cm focal length).

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Universalium. 2010.

Look at other dictionaries:

  • Diopter — (Durchsehen, Absehen) sind Zielvorrichtungen, insbesondere an geodätischen Instrumenten, jedoch auf solche Instrumente beschrankt, die eine geringe Zielgenauigkeit beanspruchen, wie z.B. Winkelklopf ( Kreuz), Neigungs (Höhen )Messer, Senkelrahmen …   Lexikon der gesamten Technik

  • Diópter — (griech., Diopterlineal), Vorrichtung zum Messen von Winkeln und Richtungen, besteht aus Okular und Objektiv, die in der Regel durch ein Lineal miteinander verbunden sind (Fig. 1), bisweilen aber auch lose nebeneinander stehen (Fig. 2). Fig. 1.… …   Meyers Großes Konversations-Lexikon

  • Diopter — Di*op ter, ||Dioptra Di*op tra, n. [L. dioptra, fr. Gr. ?. See 2d {Dioptric}.] An optical instrument, invented by Hipparchus, for taking altitudes, leveling, etc. [1913 Webster] || …   The Collaborative International Dictionary of English

  • Diopter — (lat. Dioptra, v. gr.), eine Sehritze, um dadurch nach bestimmten Gegenständen zu sehen; besteht aus einem Ocular, als dem Träger desjenigen Punktes einer Absehlinie, welche bei der Beobachtung dem Auge zunächst sich befindet, u. einem Objectiv… …   Pierer's Universal-Lexikon

  • Diópter — (grch.), Vorrichtung, um eine Visierlinie auf einen bestimmten Punkt zu richten; besteht aus zwei Teilen, deren einer dem Auge des Visierenden (Okular D.), der andere dem anzuvisierenden Gegenstand (Objektiv D.) zugekehrt ist. – Doppel D.… …   Kleines Konversations-Lexikon

  • diopter — diòpter m DEFINICIJA 1. tehn. uređaj za viziranje i mjerenje kutova 2. sport vrsta zatvorenog ciljnika (nišana) u streljaštvu ETIMOLOGIJA vidi dioptrija …   Hrvatski jezični portal

  • diopter — or dioptre [dī äp′tər] n. [Fr dioptre < L dioptra < Gr instrument for leveling, etc. < dia , through + base of opsis, sight < ops, EYE] a unit of measure of the power of a lens, equal to the power of a lens with a focal length of one… …   English World dictionary

  • Diopter — Astrolabium mit Alhidade zum Anpeilen der Himmelskörper …   Deutsch Wikipedia

  • diopter — (dpt or D)    a metric unit used in optics to measure the refractive power of a lens. Each converging lens has a focal length, defined to be the distance from the center of the lens to the point at which the lens focuses light. (Diverging lenses …   Dictionary of units of measurement

  • Diopter — dioptras statusas T sritis fizika atitikmenys: angl. diopter vok. Diopter, m rus. диоптр, m pranc. viseur, m …   Fizikos terminų žodynas

  • diopter — noun Etymology: diopter (an optical instrument), from Middle French dioptre, from Latin dioptra, from Greek, from dia + opsesthai to be going to see more at optic Date: circa 1864 a unit of measurement of the refractive power of lenses equal to… …   New Collegiate Dictionary

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