大视场离轴反射光学系统可以获取丰富的信息资源,是未来空间光学系统的发展趋势。自由曲面在离轴反射光学系统中的应用可以增大系统视场,但大视场自由曲面离轴反射光学系统初始结构较少,优化过程复杂,设计难度大。提出了一种大视场自由曲面离轴反射光学系统设计方法,首先基于矢量像差理论与费马原理直接获得成像质量较好的无遮拦自由曲面初始系统,再对其进行简单优化即可得到最终的大视场自由曲面光学系统。该方法可以降低大视场自由曲面离轴反射光学系统的设计难度。设计了一个大视场自由曲面离轴三反光学系统,光学系统视场为30°×3°,F数为2,验证了所提方法的有效性。

The off-axis reflective optical system with large field-of-view can obtain more abundant information resources, which is the development trend of the future space optical systems. The application of freeform surfaces in off-axis reflective optical systems can increase the field-of-view, but freeform off-axis reflective optical systems with large field-of-view are difficult to design due to fewer initial configurations and complicated optimization processes. In this paper, a design method for the freeform off-axis reflective optical system with large field-of-view is proposed. First, the unobscured freeform initial system with good imaging quality is directly obtained based on the vector aberration theory and the Fermat principle. Then, the final freeform optical system is obtained after simple optimization. This method can reduce the design difficulty of a freeform off-axis reflective optical system with large field-of-view. A freeform off-axis three-mirror optical system with a field-of-view of 30°×3° and an F number of 2 is designed, which verifies the effectiveness of the proposed method.