Thermal image dynamic range expander

摘要

A gas cell array absorbs infrared energy radiated by a viewed scene. A laser interferometer has its resultant intensity changed by the cell's changing length. This is monitored by a vidicon tube that feeds the signal to a digitizer and onto a video display. The incident infrared radiation is chopped into quantized amounts of energy and memory units receive the digitized output of the vidicon tube. Subtractors receive vidicon tube signals simultaneously with quiescent reference levels data. The subtractors form a difference signal by subtracting the quiescent reference level signal from the immediate signal being passed to control threshold detectors. An extended dynamic range of 1,000:1 is accomplished for the preferred embodiment.