Abstract

A design of a narrow field of view (FOV) lens for night viewing has been considered. The lens is a re-imaging Cassegrain bifocal system with hybrid elements and has a resolution of 0.0875 (mrad). The advantages of this design include the following: no large refractive element, fewer refractive elements (three germanium lenses), no stow space for removed lenses or mirrors, only one moving group to change the field of view. The narrow FOV is 0.95 (deg) and the spectral region used for the system is 8.5 pm to 12.5 µm. Noise Equivalent Temperature Difference (NETD) is calculated based on the assumption that the imaging system has an uncooled staring array detector.

© 1994 Optical Society of America