降雨对目标辐射的传输会产生严重衰减，从而给基于氧气吸收的被动测距技术带来一定的影响。在理论分析降雨天气条件下大气及雨滴粒子对目标辐射散射衰减作用的基础上，在降雨天气时对固定距离为2360 m 处的卤钨灯目标进行了被动测距实验。实验采用分辨率为1 nm 的光谱仪采集卤钨灯目标在740～790 nm 波段的光谱辐射，通过设置不同的目标提取阈值提取目标辐射光谱，并根据被动测距技术的原理计算氧气吸收率；然后利用相关K 分布法建立的氧气吸收率与路径的关系模型解算目标距离。结果表明：不同的目标提取阈值对测距精度有影响，文中选用的0.8、0.9 和0.99三个目标提取阈值，选择0.9 时测距精度最高；经平均处理后的目标光谱更接近真实光谱，测距精度高。

Rainfall can bring serious attenuation to target radiation transmission, so it will take some influence to passive ranging technology based on oxygen absorption and applied in the rain. The passive ranging technology in the rainy weather is investigated according to theoretical analysis of atmospheric and raindrop particles absorption and scattering characteristic. The test data is processed at the fixed range of 2360 m which uses a halogen lamp as the target. The spectral radiation of the target at 740-790 nm is collected by the grating spectrometer with 1 nm resolution. The oxygen absorption rate of target is calculated in accordance with the principle of passive ranging technology by setting different target extraction threshold value. Then the distance is solved according to the mathematic model of oxygen absorption rate and path length using the correlated K distribution. The results indicate that: the measurement accuracy of oxygen spectral absorption is affected by rainy weather and the target extraction threshold value, high range accuracy is achieved at the target extraction threshold value of 0.9. At the same time, the measurement spectrum is closer to the real spectrum and higher range accuracy is achieved after average processing.