当利用红外探测系统在昼夜热交替时段进行目标探测时, 由于探测场景中目标和背景温度差会发生较大变化, 使得目标和背景之间的红外辐射差异在这一阶段的某些时刻很可能接近于0, 体现在热红外图像中即为目标与背景“融合”为一体, 从而产生红外探测系统的“盲区”现象, 导致在昼夜热交替时段传统热红外探测系统无法有效识别目标。针对这一问题, 在分析热红外探测系统在昼夜热交替时段致盲原因的基础上, 提出一种基于中红外多光谱的昼夜热交替时段探测方法并研制了原理样机, 通过利用不同目标之间的红外光谱特性差异实现热交替时段目标的识别与区分。实验结果表明, 红外多光谱技术能有效提高传统热红外探测系统在昼夜热交替时段的目标探测能力, 相比同一时刻中波红外宽波段成像, 红外多光谱成像中目标和背景的DN值比值平均提高了约18%, 能够为全天时红外探测系统的实际应用提供很好的借鉴。

When detecting a target over the diurnal cycle, due to the large temperature variation of targets and background objects, the infrared image contrast between target and background in a scene would probably approach to zero, by which the target would be blended into the background in thermal infrared image, causing the blindness of thermal infrared system, lowering the detection accuracy and even making the thermal sensor lose the target. Concerning this issue, based on the brief theoretical analysis on how the thermal crossover over the diurnal cycle influenced a conventional thermal infrared system, a mid-infrared(3-5 μm) multi-spectral method using different infrared spectral characteristics of different targets to solve the issue was presented. Furthermore, the prototype design and how multispectral technology was employed to help solve the thermal crossover detection problem were also described. The experimental results show that the multi-spectral infrared imaging system can increase the contrast of the detected images by 18% compared to the MWIR broadband image and effectively solve the failure of the conventional infrared sensor during the diurnal cycle, which is of great significance for infrared surveillance applications.