红外成像光学系统近场辐射噪声建模与仿真分析

Modeling and simulation analysis of near-field radiation noise of infrared imaging system

在红外探测系统中,当目标信号比较弱时,少量的杂散光引起的噪声就会大大降低系统的输出信噪比,从而降低系统的探测能力。对于高灵敏红外成像探测系统和低冷辐射环境模拟系统,系统自身热辐射将成为杂光的最大来源。文中分析说明了系统自身热辐射杂光的确定性和近场性,提出了一种新的基于光线光学的计算模型,讨论了计算模型中的一些关键问题和解决方法,并编程实现了对近场物体杂散辐射的精确数值模拟与仿真。得到了杂光在探测器上的辐照度分布图,并分析了温度、物距和辐射系数等参数对系统杂光水平的影响。对如何合理高效地降低系统自身热辐射噪声具有指导意义。

In infrared detection systems, when the target signal is relatively weak, the noise caused by a spot of stray light will greatly reduce the SNR of system, thus reduce the system's detection capability. For highly sensitive infrared imaging system and low temperature environment simulation system, the thermal radiation emitted from the optical surfaces is the largest source of stray light. In this paper, the certainty and near-field property of self-emitted thermal radiation stray light were analyzed, and a new computational model based on ray optics was proposed. Some key problems in the calculation model were discussed, the solutions were proposed. Moreover, the near-field thermal radiation of objects was accurately numerical simulated. Distribution of irradiance on the detector was gained, the effects of temperature, distance, radiation coefficient and other parameters on the stray light level were analyzed, which has a guiding significance on reducing the system′s thermal radiation noise reasonably and efficiently.