November 2004
Intermediate to advanced
631 pages
16h 42m
English
*A significant exception to this is the infrared lens in the form of an airspaced doublet widely spaced from a positive singlet. This can be considered either as a triplet anastigmat or as a Petzval lens. This particular design configuration results from the high index and low dispersion of the infrared materials used—usually silicon and germanium for the mid-infrared, or germanium and zinc sulfide or selenide for the 8- to 12-mm region. See Chap. 19 for infrared lens designs.