Recent advances in portable infrared imaging systems

Significant progress in the manufacturing of photovoltaic HgCdTe and InSb, Schottky barrier PtSi, uncooled ferroelectrics and microbolometers, and quantum well infrared detector technologies has occurred over the last 5 years, enabling system developers to obtain high quality staring infrared focal plane arrays (IRFPAs) at a reasonable cost. Recently developed portable IR imagers using 256/spl times/256 and 320/spl times/240 staring IRFPAs have achieved thermal sensitivity unmatched by systems typically used for medical studies in the past. Cooled staring systems weighing less than 3 pounds have demonstrated thermal sensitivity below 0.020 degrees C, more than a factor of 10 improvement over comparably packaged first generation serially scanned systems. The use of high quantum efficiency (QE) staring IRFPAs offers design flexibility and performance tradeoffs that until recently were impractical. Portable cooled staring systems operating in the short (1-2.5 micron), medium (3-5 micron), and long (8-12 micron) wavelength IR spectral bands provide excellent image quality at nominal video frame rates. Staring systems can be tailored to maintain sensitivity at high frame rates and over narrow spectral bandwidths. The medical benefits associated with high sensitivity thermal imaging, calibrated radiometric imaging, wavelength and time resolved spectrometry, and realtime sensor fusion have not been fully explored. An uncooled head mounted thermal imager (HMTI) weighing 1.25 pounds is being developed by the US Army Night Vision and Electronic Sensors Directorate to assist in combat casualty care and confined environment search and rescue.