MWIR lens system for wide area motion imagery

A Mid-Wave Infrared (MWIR) objective and relay lens system has an F# of 3.33 and angular field of view of 15.28°. It is deployed, with a focal plane and scanning system, on airborne platforms for wide area motion imagery. It is corrected for monochromatic and chromatic aberrations over of 3.3 to 5.1 micrometers. Effective focal length is 20 inches, and the overall length is 40.70 inches. The lens has, from object to image, two groups of optical elements with a cold shield/aperture stop 6 inches from the image plane. Group 1 acts as an objective lens with a positive power and three elements, Group 2 acts as a relay lens has a positive power and four elements. The lens is made of Germanium and Silicon. It used in a scanning system in a pre-objective configuration where the fast scan mirror is located in front of the lens system.