- (written as Chromatic Aberration)Spurious colouring of images by a lens. It is extremely difficult to produce optical components which treat each colour of light identically. Instead, light of different wavelengths is refracted differently, producing a set of slightly separate images. Carefully designed systems, e.g. using ‘achromatic’ lenses with elements made from different types of glass, can cut the problem almost to zero.
- In a CRT, such as that in a TV, a defect in which the focal spot is enlarged and blurred. It may be due, for instance, to differences in electron velocities as they are emitted by an electron gun, and how these are differentially deflected en route to the screen.
- In an optical lens, a defect in which not all colors come to focus at the same point. May be due, for instance, to the physical properties of the lens.
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