Zhang Jialun, Zheng Yuquan, Lin Chao, Ji Zhenhua, Wu Hao
Appl Opt. 2021 Jan 10;60(2):264-275. doi: 10.1364/AO.411473.
Compact hyperspectral imaging spectrometers with a wide field of view (FoV) have significant application value. However, the aberration field of such imaging spectrometers is sensitive, and varies for different wavelengths when reducing the spectrometer volume. It is difficult to explain the variation in the aberration field using traditional aberration theory. In this study, we extend the vector aberration theory (VAT) to the Offner imaging spectrometer. We deduce the expression of the aberration field decenter vector of the Offner spectrometer based on the real ray-trace method. Furthermore, we derive the expression of the third-order vector aberration of the system. Subsequently, we explain some common phenomena in the Offner imaging spectrometer. This new analysis method can provide useful guidance for designing a compact wide FoV Offner imaging spectrometer. With this new insight, we designed a compact wide FoV Offner imaging spectrometer with a freeform tertiary mirror. Compared to conventional spectrometers with the same specifications, the total length of the spectrometer decreased by 37%, and the volume by 75%. After the tolerance analysis, the freeform optics satisfied the existing machining technology. The analysis method presented in this paper furthers the designer's understanding of the aberration field of the Offner imaging spectrometer. The method is significant in the design of a compact wide FoV Offner imaging spectrometer with freeform optics.
具有宽视场（FoV）的紧凑型高光谱成像光谱仪具有重要的应用价值。然而，此类成像光谱仪的像差场较为敏感，在减小光谱仪体积时，像差场会因不同波长而变化。使用传统像差理论难以解释像差场的这种变化。在本研究中，我们将矢量像差理论（VAT）扩展到Offner成像光谱仪。基于实际光线追迹法，我们推导出了Offner光谱仪像差场偏心矢量的表达式。此外，我们还推导了该系统的三阶矢量像差表达式。随后，我们解释了Offner成像光谱仪中的一些常见现象。这种新的分析方法可为设计紧凑型宽视场Offner成像光谱仪提供有用的指导。基于这一新见解，我们设计了一种带有自由曲面第三反射镜的紧凑型宽视场Offner成像光谱仪。与具有相同规格的传统光谱仪相比，该光谱仪的总长度减少了37%，体积减少了75%。经过公差分析，自由曲面光学元件满足现有加工技术要求。本文提出的分析方法加深了设计者对Offner成像光谱仪像差场的理解。该方法在设计带有自由曲面光学元件的紧凑型宽视场Offner成像光谱仪方面具有重要意义。
