In airborne applications there is a need for compact long range camera modules to be fitted into gyro-stabilized gimbals. The QWIP 640x480 detector operating in LWIR gives, with its high spatial and thermal resolution, a good performance. For the optics, long range means narrow field of view and long focal length. The challenge is to combine the narrow field of view with two wider fields of view for surveillance and still make it compact. The solution is to fold the optics. This normally gives optics with mounting difficulties, but by keeping the position requirement of each lens element low, the assembly is simplified. Design efforts combined with improved production techniques creates a solution based on diamond turned mirrors, lenses and diffractive elements. Narcissus effects are dealt with by means of customized AR coatings.
This paper discusses the different detector and systems technologies available today and in the near future, and how they measure up to these requirements. It is concluded that the only affordable alternative today and within the next ten years is QWIP technology. A system based on a Swedish developed and manufactured 320 X 240 QWIP has been demonstrated in the field. This and examples of other systems under development are presented.