irrationality of dispersion

irrationality of dispersion

[i‚rash·ə¦nal·əd·ē əv di′spər·zhən]
(optics)
The effect whereby spectra produced by prisms of different types of glass are not geometrically similar.
McGraw-Hill Dictionary of Scientific & Technical Terms, 6E, Copyright © 2003 by The McGraw-Hill Companies, Inc.