Tian Qijie, Chang Songtao, He Fengyun, Li Zhou, Qiao Yanfeng
Appl Opt. 2017 Jun 10;56(17):4918-4925. doi: 10.1364/AO.56.004918.
Internal stray radiation is a key factor that influences infrared imaging systems, and its suppression level is an important criterion to evaluate system performance, especially for cryogenic infrared imaging systems, which are highly sensitive to thermal sources. In order to achieve accurate measurement for internal stray radiation, an approach is proposed, which is based on radiometric calibration using a spherical mirror. First of all, the theory of spherical mirror design is introduced. Then, the calibration formula considering the integration time is presented. Following this, the details regarding the measurement method are presented. By placing a spherical mirror in front of the infrared detector, the influence of internal factors of the detector on system output can be obtained. According to the calibration results of the infrared imaging system, the output caused by internal stray radiation can be acquired. Finally, several experiments are performed in a chamber with controllable inside temperatures to validate the theory proposed in this paper. Experimental results show that the measurement results are in good accordance with the theoretical analysis, and demonstrate that the proposed theories are valid and can be employed in practical applications. The proposed method can achieve accurate measurement for internal stray radiation at arbitrary integration time and ambient temperatures. The measurement result can be used to evaluate whether the suppression level meets the system requirement.
内部杂散辐射是影响红外成像系统的关键因素，其抑制水平是评估系统性能的重要标准，特别是对于对热光源高度敏感的低温红外成像系统。为了实现对内部杂散辐射的精确测量，提出了一种基于使用球面镜进行辐射校准的方法。首先，介绍了球面镜设计理论。然后，给出了考虑积分时间的校准公式。接着，阐述了测量方法的细节。通过在红外探测器前放置一个球面镜，可以得到探测器内部因素对系统输出的影响。根据红外成像系统的校准结果，可以获取由内部杂散辐射引起的输出。最后，在一个内部温度可控的腔室内进行了多项实验，以验证本文提出的理论。实验结果表明，测量结果与理论分析吻合良好，证明了所提出的理论是有效的，可应用于实际。所提出的方法可以在任意积分时间和环境温度下实现对内部杂散辐射的精确测量。测量结果可用于评估抑制水平是否满足系统要求。
