ABSTRACT
Optical design in the infrared is similar in principle to optical design in the visible. Optical design is such a complex subject that the reader should seek the services of a competent optical designer. The chief differences between infrared and visible optical designs are in the properties of materials and the effects of the longer wavelengths. Resolution at the diffraction limit is a condition frequently approached in modern optical systems on axis. About the only real-time response options are those recognized as adaptive optics techniques. Hardening of optics and telescopes to either manmade or natural effects necessitates a review of all the mechanisms by which energy can be deposited in the optics to their detriment. The technology of adaptive optics was initiated at least as early as the 1930s when open-loop corrections for gravity sag were appended to the Mt. Palomar 200-in.
