Double refraction

Double refraction
Refraction Re*frac"tion (r?*fr?k"sh?n), n. [F. r['e]fraction.] 1. The act of refracting, or the state of being refracted. [1913 Webster]

2. The change in the direction of ray of light, heat, or the like, when it enters obliquely a medium of a different density from that through which it has previously moved. [1913 Webster]

Refraction out of the rarer medium into the denser, is made towards the perpendicular. --Sir I. Newton. [1913 Webster]

3. (Astron.) (a) The change in the direction of a ray of light, and, consequently, in the apparent position of a heavenly body from which it emanates, arising from its passage through the earth's atmosphere; -- hence distinguished as atmospheric refraction, or astronomical refraction. (b) The correction which is to be deducted from the apparent altitude of a heavenly body on account of atmospheric refraction, in order to obtain the true altitude. [1913 Webster]

{Angle of refraction} (Opt.), the angle which a refracted ray makes with the perpendicular to the surface separating the two media traversed by the ray.

{Conical refraction} (Opt.), the refraction of a ray of light into an infinite number of rays, forming a hollow cone. This occurs when a ray of light is passed through crystals of some substances, under certain circumstances. Conical refraction is of two kinds; external conical refraction, in which the ray issues from the crystal in the form of a cone, the vertex of which is at the point of emergence; and internal conical refraction, in which the ray is changed into the form of a cone on entering the crystal, from which it issues in the form of a hollow cylinder. This singular phenomenon was first discovered by Sir W. R. Hamilton by mathematical reasoning alone, unaided by experiment.

{Differential refraction} (Astron.), the change of the apparent place of one object relative to a second object near it, due to refraction; also, the correction required to be made to the observed relative places of the two bodies.

{Double refraction} (Opt.), the refraction of light in two directions, which produces two distinct images. The power of double refraction is possessed by all crystals except those of the isometric system. A uniaxial crystal is said to be optically positive (like quartz), or optically negative (like calcite), or to have positive, or negative, double refraction, according as the optic axis is the axis of least or greatest elasticity for light; a biaxial crystal is similarly designated when the same relation holds for the acute bisectrix.

{Index of refraction}. See under {Index}.

{Refraction circle} (Opt.), an instrument provided with a graduated circle for the measurement of refraction.

{Refraction of latitude}, {longitude}, {declination}, {right ascension}, etc., the change in the apparent latitude, longitude, etc., of a heavenly body, due to the effect of atmospheric refraction.

{Terrestrial refraction}, the change in the apparent altitude of a distant point on or near the earth's surface, as the top of a mountain, arising from the passage of light from it to the eye through atmospheric strata of varying density. [1913 Webster]

The Collaborative International Dictionary of English. 2000.

Look at other dictionaries:

• Double refraction — Double Dou ble (d[u^]b l), a. [OE. doble, duble, double, OF. doble, duble, double, F. double, fr. L. duplus, fr. the root of duo two, and perh. that of plenus full; akin to Gr. diplo os double. See {Two}, and {Full}, and cf. {Diploma}, {Duple}.]… …   The Collaborative International Dictionary of English

• double refraction — n. BIREFRINGENCE …   English World dictionary

• Double réfraction — Biréfringence Le texte apparait en double après avoir traversé le cristal de calcite. C est la double réfraction, un phénomène caractéristique des milieux biréfringents La biréfringence est la propriété physique d un matériau dans lequel la… …   Wikipédia en Français

• double refraction — Optics. the separation of a ray of light into two unequally refracted, plane polarized rays of orthogonal polarizations, occurring in crystals in which the velocity of light rays is not the same in all directions. Also called birefringence. [1870 …   Universalium

• double refraction — dvejopas lūžimas statusas T sritis fizika atitikmenys: angl. birefringence; double refraction vok. Doppelbrechung, f rus. двойное преломление, n; двупреломление, n pranc. biréfringence, f; double réfraction, f …   Fizikos terminų žodynas

• double réfraction — dvejopas lūžimas statusas T sritis fizika atitikmenys: angl. birefringence; double refraction vok. Doppelbrechung, f rus. двойное преломление, n; двупреломление, n pranc. biréfringence, f; double réfraction, f …   Fizikos terminų žodynas

• double refraction — dvejopas spindulių lūžimas statusas T sritis Standartizacija ir metrologija apibrėžtis Anizotropinėje terpėje sklindančio šviesos spindulio skaidymasis į du spindulius. atitikmenys: angl. birefringence; double refraction vok.… …   Penkiakalbis aiškinamasis metrologijos terminų žodynas

• double refraction — dvejopas spindulių lūžimas statusas T sritis chemija apibrėžtis Anizotropinėje terpėje sklindančio šviesos spindulio skaidymasis į du spindulius. atitikmenys: angl. birefringence; double refraction rus. двойное лучепреломление …   Chemijos terminų aiškinamasis žodynas

• Double refraction micrometer — Micrometer Mi*crom e*ter, n. [Micro + meter: cf. F. microm[ e]tre.] An instrument, used with a telescope or microscope, for measuring minute distances, or the apparent diameters of objects which subtend minute angles. The measurement given… …   The Collaborative International Dictionary of English

• double refraction — noun splitting a ray into two parallel rays polarized perpendicularly • Syn: ↑birefringence • Derivationally related forms: ↑birefringent (for: ↑birefringence) • Hypernyms: ↑refraction …   Useful english dictionary