achromatic lens

lens (lenz)

1. a piece of glass or other transparent material so shaped as to converge or scatter light rays; see also glasses.

Lenses: (A–F), Spherical lenses: (A), biconvex; (B), biconcave; (C), planoconvex; (D), planoconcave; (E), concavoconvex, periscopic convex, converging meniscus; (F), convexoconcave, periscopic concave, diverging meniscus; (G, H), cylindrical lenses, concave and convex.

2. crystalline l.; the transparent, biconvex body separating the posterior chamber and vitreous body, and constituting part of the refracting mechanism of the eye.

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achromatic lens  one corrected for chromatic aberration.

aplanatic lens  one for correcting spherical aberrations.

bandage lens  a soft contact lens worn on a diseased or injured cornea to protect or treat it.

biconcave lens  one concave on both faces.

biconvex lens  one convex on both faces.

bifocal lens  one with two parts of different refracting powers, the upper for distant and the lower for near vision.

concavoconvex lens  one with one concave and one convex face.

contact lens  a curved shell of glass or plastic applied directly over the globe or cornea to correct refractive errors. It may be a soft (hydrophilic) contact l., flexible and water absorbent, or a hard (hydrophobic) contact l., rigid and not water absorbent; the latter type is subdivided into gas permeable and non–gas permeable, usually polymethylmethacrylate (PMMA), lenses.

convexoconcave lens  one with one convex and one concave face.

crystalline lens  lens (2).

cylindrical lens  one for correcting astigmatism, with one plane surface and one cylindrical, or one spherical surface and one toroidal. Symbol C.

decentered lens  one whose optical axis does not pass through the center.

honeybee lens  a magnifying lens resembling the multifaceted eye of the honeybee, consisting of three or six small telescopes mounted in the upper part of the lens and directed toward the center and right and left visual fields. Prisms are included to provide a continuous, unbroken magnified field of view.

omnifocal lens  one whose power increases continuously and regularly in a downward direction, avoiding the discontinuity of bifocal and trifocal lenses.

planoconvex lens  a lens with one plane and one convex side.

spherical lens  (S) (sph) one that is a segment of a sphere.

trial lens  one used to test vision.

trifocal lens  one with three parts of different refracting powers, the upper for distant, the middle for intermediate, and the lower for near vision.

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achromatic lens

n.

A combination of lenses made of different glass, used to produce images free of chromatic aberrations.

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achromatic lens

[ak′rəmat′ik]

Etymology: Gk, a, without, chroma, color; L, lens

a lens in which the focal lengths for red and blue colors of the spectrum are the same, refracting light without decomposing it into its component colors.