Design and analysis of a multi-element dual band infrared detector for counter-countermeasure

A dual band multi-element infrared (IR) detector which enables effective target tracking in a complex tactical environment is presented. The photosensitive elements are designed like the stripes of the Lovell optical reticle and arranged close to each other. The thin films of the dual band filter are precisely coated onto an IR transparent substrate, which is then bonded directly onto the surface of photosensitive area with an IR transparent adhesive. The optical system of the detector adopts a spin-scan mode. The filter-detector combination rotates with a mechanical rotor during scanning. The dual band filters temporally encode target location into the incoming radiation signals, and the photosensitive elements then convert the modulated radiation into an electrical signal. The ratio of radiation intensity from two bands can be calculated to distinguish target from IR target-flare mixed signals. Because the pattern of the detector is similar to the Lovell reticle, the detector can also perform spatial filtering to eliminate background noise. In addition, relatively high stability, together with simplicity of the hardware and low cost, indicates that the presented method has a potential application at the field in which precision is not strictly requested.