Abstract
In infrared systems, enhancing the sensitivity and imaging quality of infrared detectors necessitates operation under extreme low-temperature conditions, which presents formidable challenges to the surface accuracy and stability of optical components. To minimize payload weight and volume while achieving a wide field of view and miniaturization, a multi-optical-path stitching optical system is employed. Within this system, mirrors, serving as optical redirecting components, are indispensable. Traditional reflective prisms are predominantly crafted from optical glass and secured via structural clamping mechanisms. Nevertheless, this conventional reflective prism design does not adequately account for the effects of low temperatures on material properties. Particularly when a high aspect ratio is required for the prism, ordinary optical glass significantly lacks the necessary stiffness. This paper introduces an integrated all-metal quadrilateral prism with a large aspect ratio and its supporting structure, employing high-stiffness and high-strength metal materials as the prism's base material to achieve seamless integration between the supporting structure and the prism. A flexible joint is incorporated into the integrated design. This quadrilateral prism combines the merits of a rigid structure with flexible support, enabling it to effectively adapt to environments with significant temperature variations while maintaining precise surface accuracy and optical performance. This design demonstrates excellent adaptability to large temperature differentials, ensuring that the quadrilateral prism's surface accuracy and optical performance remain satisfactory even under a temperature variation of 200K. The integrated design of the prism body and its supporting structure offers robust strength and high stiffness, reduces the number of assembly steps, and simplifies the process of ensuring assembly and alignment accuracy. Additionally, the design features rigid positioning at one end and flexible release of axial thermal stress at the other, effectively dispersing and mitigating thermal stress induced by temperature fluctuations. This paper presents the design and research of an integrated all-metal quadrilateral prism with a large aspect ratio and its supporting structure, achieving structural optimization through optimization algorithms and validating the design through physical experiments.