Numerical estimations of the maximal distance of target detection in the IR spectrum with decreasing the target–background temperature contrast

This paper discusses the distance limit of target detection in the infrared (IR) spectrum for targets with different temperatures. Numerical estimations of the relative decrease in the maximum detection range (MDR) with a decreasing temperature contrast of the target relative to the background (ΔT) are presented. It is shown that an order-of-magnitude decrease in ΔT leads to a decrease in the MDR by approximately one-third, while a two-order-of-magnitude decrease in ΔT results in an approximately two-thirds decrease in the MDR. Estimates of the MDR were carried out for favorable and unfavorable weather conditions. These results are relatively valid for both the 3…5 and 8…12 μm spectral ranges and seem to be independent of weather condition.