为求解红外热成像系统作用距离, 以MODTRAN程序为基础, 计算了不同云雨条件下的大气光谱透过率, 并针对探测器定角度运行和定高度运行, 分别运用光谱-路径等分法和光谱-角度等分法, 对点源目标进行了红外热成像系统的探测距离求解。分析了卷云气象条件下, 探测概率、降雨速率、云层厚度、云底高度等因素对大气光谱透过率和探测距离的影响。结果表明: 探测概率的选取对热像仪探测距离计算结果影响较大, 以坦克目标为例, 探测概率由10%增加至90%时, 探测距离降低21.7%; 降雨对于大气透过率和探测距离影响也较大, 降雨速率由0增加至4.0 mm/h时, 探测距离降低76.8%; 云底厚度和云层高度的影响与探测器和云层的几何位置关系相关, 人目标的探测距离上限值达5.60 km; 探测距离亦与探测器运行模式相关, 最大差异3.8%左右。

To solve the detection distance of infrared thermal imager, using MODTRAN program, the atmospheric spectral transmittance in different cloud and rain conditions was calculated. For detector angle-fixed and height-fixed operating, using the spectrum-path bisection method and spectrum-angle bisection method respectively, the thermal imaging system detection distances of point source target were evaluated. Under cirrus weather conditions, the effects of the detection probability, rainfall rate, cloud thickness and cloud base height on the atmospheric spectral transmittance and the detection distance were analyzed. The results show that the selection of detection probability of infrared thermal imaging system has a great influence on the detection distance. In the case of tank target, when the detection probability increases from 10% to 90%, the detection distance reduces by 21.7%. The rainfall rate also has a great influence on atmospheric transmittance and the detection distance. When the rainfall rate increases from 0 to 4.0 mm/h, the detection distance decreases by 76.8%. The effects of the cloud thickness and cloud base height are associated with the geometric position relationship between the detector and the cloud. The upper bound of the detection distance of human target is 5.60 km. The detection distance is also influenced by the detector operating model. The biggest difference is about 3.8%.