Signal Processing For Staring Infrared Images

The signal from a staring infrared imager, initially in the charge domain, is characterized by low contrast and nonuniformities. To achieve high performance, the signal processor should have low noise and operate with background suppression. Fixed pattern noise compensation must also be available. Low noise multiplexing can be achieved with charge coupled devices (CCD). With a hybrid focal plane, background suppression at the Si CCD input can be achieved with charge partitioning, charge skimming, accoupling or fill/spill gain reduction. Fixed pattern noises arising from detector variations, CCD input threshold variations, charge transfer process and other sources, must be compensated electronically using optical calibration. A performance model of the input circuit taking into account the various noise sources will be discussed and compared with experimental data. Data on focal plane fixed pattern noises will be presented. Various techniques to implement the nonuniformity correction, especially in a tactical system, will also be discussed.