杜瓦真空失效造成光电转换探测系统的核心部件故障，依据真空物理稀薄气体理论，分析探讨了真空失效考核方法。检测组件在工作状态下的降温时间是否符合用户要求，是确认真空失效最直接有效的方法。制冷机额定制冷功率与杜瓦最大无功功率之差，即设计允许最大热负载增加量。在特定时间区间内，利用液氮蒸发原理测量热负载增加量，达到扩展不确定度30 mW(k=3)时，可以认为杜瓦真空有用寿命不符合用户要求。用户定制15年真空有用寿命，则要求杜瓦漏气速率小于5×10^-15 Pa?m³/s，真空失效的气体压力大于1×10^-2 Pa。

Dewar vacuum failure is usually caused by IR FPA device malfunction, and the evaluation hereby used is testified as a valid method in discussing and analyzing such failure in accordance with Low Density Gas Theory of Vacuum Physics, The IR FPA Dewar device cooling time is regarded as the most direct and effective method in confirming such failure. Notice that the maximum heat loading variation between the maximum reactive power of IR FPA Dewar device and the rated capacity of the cooler should be in correspondence with its use-defined maximum cooling time. And Dewar vacuum life is considered unacceptable if the heat load variation being measured by LN Evaporation Principle is under such condition that the variation is within its specified time in the case it reaches expanded uncertainty(k=3). The value tested should be 30 mW. Within the customized vacuum service life of specified 15 years，the Dewar leakage and gas rate required must be less than 5×10^-15 Pa?m³/s. As the failure of Dewar vacuum occurred, and simultaneously, the gas pressure must be greater than 1×10^-2 Pa.