测试装置空间分布对红外相机噪声等效温差测试的影响

Effect of Spatial Distribution of Test Device on Noise Equivalent Temperature Difference Test of Infrared Camera

红外相机的噪声等效温差(NETD)是评价成像质量的一项重要准则.红外相机NETD测试装置中的黑体辐射源、靶标、入瞳(平行光管加待测相机)三者的位置、口径需要满足一定的数学关系,否则会降低测试精度.基于几何光学理论、辐射度学,推导出红外相机测试系统中黑体辐射源、靶标、入瞳三者的空间分布关系,研究靶标孔处的测量温度与后方黑体辐射源温度之间的关系,建立数学模型,指导红外相机测试系统的试验,并结合一套测试系统,验证了测试装置空间分布满足本模型要求时,相对误差小于7.4%,否则测试精度迅速下降.分析了以靶标为目标时,靶标孔处的温度均匀性和稳定度的变化.

The noise equivalent temperature difference(NETD)of infrared cameras is a crucial criterion for evaluating the imaging quality.The position and aperture of the blackbody source,target,and entrance pupil(the collimator and the camera to be measured as a whole)in an infrared camera NETD test device should meet the specific mathematical relationship,otherwise the test accuracy will be reduced.Therefore,based on geometrical optics theory and radiology,the spatial distribution of the blackbody source,target,and entrance pupil in the infrared camera testing system is deduced in this study.Additionally,the relationship between the measured temperature at the target hole and the blackbody source temperature at the rear is explored.A mathematical model has been established to guide the test of the infrared camera test system.Combined with a test system,the relative error is verified to be less than 7.4%when the spatial distribution of the test device meets the proposed model requirement;otherwise the test accuracy decreases rapidly.The temperature uniformity and stability at the target hole are analyzed when the target is used.