现有所发布的大多数文献着重于图像融合算法的分析研究，很少有文献对采集融合图像的光学系统做出相应论述。本文根据手持融合观察镜的特点，对可见光/微光与长波红外图像融合、平行光路布局型式的融合物镜光学系统进行设计及分析。首先介绍了共光路光学布局型式与平行光路光学布局型式的优缺点，根据手持融合观察镜的特点选择了平行光路的光学布局型式；其次根据手持融合观察镜指标的要求对可见光/微光物镜进行“消热差”、定焦光学设计，针对长波红外物镜开展内调焦式光学设计；第三根据所设计的融合物镜光学系统，从平行光路光学布局型式、放大率及畸变变化 3个方面对图像配准精度进行分析；最后对手持融合观察镜实际场景的融合图像进行分析判断，得出融合图像质量好，能满足手持融合观察镜融合性能的要求。

Most of the published literature relating to parallel optical path fusion focuses on analysis and research of image fusion algorithms; little literature discusses the optical system for image fusion. This paper designs and analyzes a fusion optical system of visible light /low-light and a long wave infrared image fusion and parallel light path layout according to the characteristics of a hand-held fusion observation lens. Firstly, the advantages and disadvantages of a shared optical path optical layout pattern and parallel optical path optical layout pattern were introduced. The optical layout pattern of the parallel optical path was selected according to the characteristics of the handheld fusion observation lens. Secondly, according to the requirements of the hand-held fused observation lens, the “heat dissipation difference” and fixed-focus optical design of the visible light /low-light optical objective lens were determined and the internal focusing optical design was performed for the long-wave infrared objective lens. Thirdly, the image registration accuracy was analyzed from the three aspects of the optical layout, magnification, and distortion of the parallel light path, according to the design of the fused optical system. Finally, the fusion image of the actual scene of the handheld fusion observation lens was analyzed and judged; it was found that the fusion image quality is suitable and the fusion performance of the handheld fusion observation lens can meet the requirements.