Yang Tong, Zhu Jun, Hou Wei, Jin Guofan
Opt Express. 2014 Apr 21;22(8):9193-205. doi: 10.1364/OE.22.009193.
In this paper, a novel method is proposed to design the freeform off-axis reflective imaging systems. A special algorithm is demonstrated to calculate the data points on the unknown freeform surface using the rays from multiple fields and different pupil coordinates. These points are used to construct the multiple three-dimensional freeform surfaces in an imaging system which works for a certain object size and a certain width of light beam. An unobscured design with freeform surfaces can be obtained directly with this method, and it can be taken as a good starting point for further optimization. The benefit of this design method is demonstrated by designing a freeform off-axis three-mirror imaging system with high performance and system specifications. The final system operates at F/1.49 with a 64mm entrance pupil diameter and an 8° × 9° field-of-view (FOV). The performance of the system is diffraction limited at LWIR (long-wavelength-infrared).
本文提出了一种设计自由曲面离轴反射成像系统的新方法。展示了一种特殊算法，利用来自多个视场和不同光瞳坐标的光线来计算未知自由曲面上的数据点。这些点用于在成像系统中构建多个三维自由曲面，该成像系统适用于特定的物体尺寸和特定宽度的光束。使用这种方法可以直接获得具有自由曲面的无遮拦设计，并且它可以作为进一步优化的良好起点。通过设计一个具有高性能和系统规格的自由曲面离轴三镜成像系统，证明了这种设计方法的优势。最终系统在F/1.49下运行，入瞳直径为64mm，视场为8°×9°。该系统在长波红外（LWIR）波段的性能受衍射限制。
