Ăch'ro-măt'ic, a.

(Synop., § 130), a. [N. Lat. achromaticus, Gr. ἀχρωματος, from ἀ priv. and χρώμα, color; Fr. achromatique.] (Opt.) Free from color; not showing color from the decomposition of light; as, an achromatic lens or telescope.

Achromatic lens, a lens composed usually of two separate lenses, a convex and a 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 the other, and light emerges from the compound lens undecomposed.—An achromatic telescope, or microscope, one in which the chromatic aberration is corrected, usually by means of a compound or achromatic object-glass.