热机械光读出非制冷红外成像系统建模分析

Modeling and Analysis of the Thermal-mechanical Optical Readout Uncooled Infrared Imaging System

针对热机械光读出非制冷红外成像系统缺乏系统级噪声模型的问题,本文提出了一种光电耦合模型。此模型以光电耦合器件的模式体现了光读出非制冷红外系统的噪声隔离特性。基于此模型,文中将系统噪声划分为由焦平面阵列(FPA)引入的内部噪声和由于光读出系统引入的外部噪声。理论计算显示,系统的内部噪声对应的噪声等效温差(NETD)为5.94mK。实验结果显示,系统的外部噪声对应的NETD与系统的总噪声对应的NETD相当,为98mK。此结果说明,理论模型中对内部噪声影响的推断是合理的,且光读出成像系统的噪声主要源自外部噪声。

To describe and analyze the system level noises of the thermal-mechanical optical readout uncooled infrared imaging system, a photoelectricity coupling model is presented. The photoelectricity coupling device in the model shows the noise isolation characteristic of the optical readout IR imaging system. Based on the model, the noises are partitioned into two kinds： intemal noises which are from the Focal Plane Array （FPA）, and extemal noises which are from the optical readout system. The Noise-equivalent Temperature Difference （NETD） caused by internal noises is calculated to be 5.94 mK theoretically. Experiment shows that the NETD caused by external noises is 98 mK, which is close to the NETD caused by the whole noises of the system. The results indicate that the calculation of NETD caused by the internal noises is reasonable and the primary noise problem of the IR imaging system is from the optical readout system.