Abstract

Specifications for scanning optical systems such as thermal imaging systems, are usually bound by image distortion, maximum lens or aperture size, and display brightness uniformity. The uniformity of the display depends directly on the relative irradiance of the infrared detector focal plane; the relative irradiance depends on the variation with image position of the optical system numerical aperture; the numerical aperture varies with exit pupil distortion; image distortion referred to the object field depends on the relative irradiance of the image and the entrance pupil distortion. General expressions are derived which relate image distortion, relative image plane irradiance, and pupil distortion to each other for various positions of the aperture stop within an optical system. These expressions are examined in detail for scanning optical systems, particularly thermal imaging systems, for the purpose of establishing the conditions in which simultaneous specifications for image distortion, pupil size, and display brightness are practical or possible.

© 1986 Optical Society of America