a. [f. Gr. ἀχρώματ-ος colorless (f. ἀ priv. + χρῶματ- color) + -IC.]
1. Optics. Free from color; not showing color from the decomposition of light in passing through a refracting medium; as an achromatic lens or telescope. (Sometimes used substantively by ellipsis of ‘lens,’ as ‘a four-inch achromatic.’)
1766. Maty (tr. from Fr.), in Phil. Trans., LVI. 57. I likewise made use of a very good achromatic telescope.
1784. Herschel, in Phil. Trans., LXXV. 44. One of Mr. Dollond’s best 31/2 feet achromatics.
1805. Edin. Rev., April, 34. The fact, that the eye is achromatic, cannot be doubted.
1831. Brewster, Optics, ix. § 67. 83. They … will refract white light to a single focus free of colour. Such a lens is called achromatic.
1848. Quekett, Microscope (1855), 37. In 1747 … Euler suggested the construction of achromatic object-glasses.
1859. Parkinson, Optics, ix. 154. A combination of prisms or lenses is said to be achromatic when the dispersion of the pencils of light refracted through them is reduced within the narrowest possible limits.
1869. Tyndall, Lect. on Light, 42. The human eye is not achromatic. It suffers from chromatic aberration.
1878. Newcomb, Pop. Astron., II. i. 125. An achromatic of four inches aperture was then considered of extraordinary size.
2. Biol. Of tissue: Uncolored, not absorbing color from a fluid. See ACHROMATIN.
1882. J. T. Cunningham in Jrnl. Microsc. Sc., Jan., 41. Figs. 30 and 31, from the cranial cartilage of a toad, show the achromatic striæ more clearly.
