红外成像系统响应光谱非均匀性的理论分析

Theory of nonuniformity related to spectrum response in IR imaging system

基于黑体标定的非均匀性校正方法在凝视红外成像系统中被广泛应用,但在面对天空背景成像或者高速飞行器上透过高温光学窗口观察常温目标两种情况下,出现了黑体标定不适用的现象。为此通过分析红外成像系统的响应特性,提出了响应光谱非均匀性的概念,指出了黑体标定法具有场景光谱分布依赖的特征。同时,分析了响应光谱非均匀性产生的原理,包括内外两方面原因。内在因素是红外探测器不同像元的量子效率随光谱变化存在差异,外在因素是应用场景的辐射光谱分布与黑体相差较大。在此基础上,给出了解决响应光谱非均匀性的建议。

Non-uniformity correction based on blackbody calibration is widely used in staring infrared imaging system. But in some cases, blackbody calibration method is not applicable. Two kinds of cases were presented: when the IR imaging system facing to the sky background, or observing normal objects through high temperature optical window in high speed aircraft. Based on the analysis of the response characteristics of infrared imaging system, the concept of non-uniformity with response spectral was proposed. It was pointed out that the correction results of blackbody calibration method depended on the spectral distribution of scene. The principle of non-uniformity with response spectrum was analyzed,which included internal and external reasons. The intrinsic factor was that the quantum efficiency of different pixels of infrared detector varies with spectrum, and the external factor was that the radiation spectrum distribution of application scene was quite different from blackbody. Suggestions were given to solve response spectral non-uniformity.