进行辐射测量时，目标尺寸过小或者距离很远都会导致其在红外探测器上成像面积较小以至于不能作为扩展源直接测量，另外目标成像往往占据多个像元，因此也无法作为传统意义上的点源处理。为解决这一问题，在现有的点源目标测量方法的基础上，提出了一种针对红外小目标的辐射特性测量方法。通过实验和理论分析研究了小目标成像特征，说明其辐射测量与扩展源的不同；通过对目标成像区域去除背景辐射推导小目标辐射测量公式；利用中波红外成像系统进行小目标的辐射测量实验，实验结果证明了该方法的有效性。

During a radiation measurement mission, the target size may be too small or quite far away, which results in small infrared target images that can not be measured directly as an extended source. However, the target image tends to occupy several pixels, and therefore can not be treated as a traditional point source. Aiming at this problem, a small target radiation characteristics measurement method, based on the traditional measurement method of point source is proposed. The imaging characteristics of small targets are studied by experiments and theoretical analysis for the purpose to explain the difference between extended source and small target. A formula for small target radiation measurement is deduced by subtracting the background radiance from the target area. Finally, a mid-wave infrared imaging system is used for small target radiometric experiments, and the results indicate that the proposed method is effective.