MINIMUM THRESHOLD TEMPERATURE DIFFERENCE DETECTABLE BY THERMAL IMAGING

The spectral dependence of the threshold temperature difference that i s equivalent to radiation noise and that can be detected from thermal radiation is calculated. The absolute limit of the threshold temperatu re difference increases as the temperature of the object decreases. Th is relationship causes a decrease of the information capacity of therm al images as the temperature of the object decreases. Thermal viewers that operate in the 8-14-mum atmospheric window have a calculated mini mum detectable temperature difference for an ambient temperature of ap proximately 300 K that differs by only 12-33% from the absolute limit and are extremely efficient detectors of small thermal contrasts.