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g or having power to refract, or turn from a direct course; pertaining to refraction; as, refractive surfaces; refractive powers. Refractive index. (Opt.) See Index of refraction, under Index. -- Absolute refractive index (Opt.), the index of refraction of a substances when the ray passes into it from a vacuum. -- Re…

The quality or condition of being refractive.

osed usually of two separate lenses, a convex and concave, of substances having different refractive and dispersive powers, as crown and flint glass, with the curvatures so adjusted that the chromatic aberration produced by the one is corrected by other, and light emerges from the compound lens undecomposed. -- Achrom…

Unequal refractive power in the two eyes.

lected, and no portion of it transmitted. The sine of this angle is the reciprocal of the refractive index of the medium. -- Critical philosophy, the metaphysical system of Kant; -- so called from his most important work, the "Critique of Pure Reason." - - Critical point (Physics), a certain temperature, different for…

A unit employed by oculists in numbering glasses according to the metric system; a refractive power equal to that of a glass whose principal focal distance is one meter.

Of or pertaining to dioptrics; assisting vision by means of the refraction of light; refractive; as, the dioptric system; a dioptric glass or telescope. "Dioptrical principles." Nichol. Dioptric curve (Geom.), a Cartesian oval. See under Cartesian.

That refractive condition of the eye in which the rays of light are all brought accurately and without undue effort to a focus upon the retina; -- opposed to hypermetropia, myopia, an astigmatism.

A condition of the eye in which, through shortness of the eyeball or fault of the refractive media, the rays of light come to a focus behind the retina; farsightedness; -- called also hyperopia. Cf. Emmetropia.

es in the given number. It is also called the characteristic. -- Index of refraction, or Refractive index (Opt.), the number which expresses the ratio of the sine of the angle of incidence to the sine of the angle of refraction. Thus the index of refraction for sulphur is 2, because, when light passes out of air into…

employment of subjective and objective mechanical means to determine the accomodative and refractive states of the eye and the scope of its function in general."

A highly refractive vitreous composition, variously colored, used in making imitations of precious stones or gems. See Strass.

Pertaining to, or possessing, refringency; refractive; refracting; as, a refringent prism of spar. Nichol.

A device for determining the refractive state of the eye by observing the movements of the retinal lights and shadows. -- Ski*as"co*py (#), Ski*as"co*py (#), n.