from The Century Dictionary.
- noun The state or quality of being achromatic; absence of coloration: as, to secure perfect achromatism in a telescope.
from the GNU version of the Collaborative International Dictionary of English.
- noun The state or quality of being achromatic; ; achromaticity.
from Wiktionary, Creative Commons Attribution/Share-Alike License.
- noun The state or quality of being
achromatic; as, the achromatism of a lens; achromaticity.
- noun The state of being free of
colors, not emittingor separatinginto colors.
from WordNet 3.0 Copyright 2006 by Princeton University. All rights reserved.
- noun the visual property of being without chromatic color
from Wiktionary, Creative Commons Attribution/Share-Alike License
Very occasionally a person lacks all color-receptors and is completely color-blind, a condition called achromatism (ay-kroh'muh-tiz-um; "no color" G).
Although this peculiar disharmony in the dispersive powers of the two glasses, crown and flint, was discovered almost immediately after achromatism was invented, it was only recently that the first successful attempts were made to produce different glasses, which, possessing the other requirements for achromatic objectives, would produce coincident spectra, or nearer so than the ordinary crown and flint glass do.
This increase is due in part to the diffraction of the telescope, to imperfect achromatism or spherical aberration of the objective, to irregular grinding of the glass, and especially to variations in the refraction of the air, which produce an oscillation of the image around a mean position.
As the diameter of the lens was so small in comparison with its focal length, its want of achromatism was inappreciable.
[*] The power which the eye possesses of adaptation to near and distant objects, combining the uses of the microscope and the telescope, and the capacity of self-adjustment, preserving always a perfect achromatism and freedom from spherical aberration, have never been reached in nearly the same degree by art.
True achromatism cannot be obtained with ordinary flint and crown-glass; and although in lenses of "Jena glass," outstanding colour is reduced to about one-sixth its usual amount, their term of service is fatally abridged by rapid deterioration.
And the mere fact that the problem of achromatism was solved by "the mind of a sagacious optician inquiring how this matter was managed in the eye," no more proves that
A long list of indictments might indeed be brought against the eye -- its opacity, its want of symmetry, its lack of achromatism, its partial blindness.
 The principle of achromatism was discovered (by
Thus examined, the departure of the eye from achromatism appears very gross indeed.] [Footnote 7: Both in foliage and in flowers there are striking differences of absorption.