应用于空间环境的低温目标红外探测系统，其作用距离是系统的重要性能指标。本文推导 了以红外焦平面探测器噪声为主要因素的点目标红外探测系统的作用距离估算方程，结合实例求解了典型红外探测系统的探测系统的作 用距离。针对空间低温点目标，基于信噪比判断准则，采用能量等效和尺度缩比等效的方法在实验室内验证了红 外探测系统的作用距离，测试结果符合理论估算。试验表明，该方法可在实验室内用于评估低温点目标红外探测系统的作用距离。

Operating distance is an important specification of infrared systems for detecting low temperature targets in space. By taking the noise of an infrared focal plane detector as the main factor, an operating distance estimation equation for point targets is derived. A calculation example of the operating distance of a typical infrared detection system is given. For the low temperature point target in space, the operating distance of the infrared detection system is verified by using both an energy equivalent method and a dimension equivalent method according to the signal-to-noise criterion in laborotary. The measured result is in agreement with the theoretical estimation. The test shows that the method can be used to evaluate the operating distance of an infrared detection system for detecting low temperature point targets in laboratory.