Design of a high-resolution high-magnification MWIR continuous zoom lens system

This paper reports a design of a high magnification mid- wave infrared (MWIR) continuous zoom lens system that is compatible with a high-resolution focal plane array (FPA). The zoom lens design has been developed via a series of optimization processes, from a global search to look for potential design candidates, to different local optimization strategies to balance out optical aberrations between different zoom configurations, then comes a few minor adjustments in order to mitigate the negative effects that the optical system might encounter during its operation. By using these processes, an F/5.5 continuous zoom lens system with a magnification ratio of 22x that works with an SXGA (1280 x 1024) cooled detector having a pixel pitch of 15 mu m has been successfully designed. This zoom lens system only makes use of two movable lenses to maintain its performance throughout the entire zoom range. With a maximum focal length of 1200 mm, this optical system plays a major role in extremely long range observation and surveillance applications.