Ji Yiqun, Han Jizhou, Zhao Shijia, Wang Chinhua
Appl Opt. 2023 Aug 1;62(22):5991-5998. doi: 10.1364/AO.498327.
Wide spectrum and miniaturization are the main challenges in the imaging spectrometer design. In this paper, we propose an ultra-compact dual band imaging spectrometer (CDBIS) with cemented freeform prisms, which works at both the visible-near-infrared (VNIR) from 400 nm to 1000 nm and the shortwave-infrared (SWIR) from 1000 nm to 1700 nm. The imaging spectrometer is only composed of three cemented prisms, a primary prism and two triangular prisms. And a freeform surface characterized by the Zernike polynomial is introduced in each prism. The CDBIS is dispersed by a diffraction grating, which is designed on the second surface of the primary prism. Based on vector aberration theory (VAT), the relationship among the astigmatism generated by the introduced freeform surfaces, the wavelength, and the field of view is studied. Accordingly, a wideband is realized by introducing the freeform surfaces after the diffraction grating. Furthermore, through optimizing the coefficients of Zernike polynomial terms, residual astigmatism at different wavelengths is well balanced. An imaging spectrometer with a volume of only 100 is obtained, with a spectral resolution of 1.45 nm at VNIR and 2.40 nm at SWIR, respectively. It has a huge potential for broadband space exploration.
宽光谱和小型化是成像光谱仪设计中的主要挑战。在本文中，我们提出了一种采用胶合自由曲面棱镜的超紧凑型双波段成像光谱仪（CDBIS），它在400纳米至1000纳米的可见近红外（VNIR）波段和1000纳米至1700纳米的短波红外（SWIR）波段均可工作。该成像光谱仪仅由三个胶合棱镜组成，一个主棱镜和两个三角棱镜。并且在每个棱镜中引入了以泽尼克多项式表征的自由曲面。CDBIS由一个衍射光栅进行色散，该衍射光栅设计在主棱镜的第二个表面上。基于矢量像差理论（VAT），研究了引入的自由曲面产生的像散、波长和视场之间的关系。相应地，通过在衍射光栅之后引入自由曲面实现了宽带。此外，通过优化泽尼克多项式项的系数，不同波长下的残余像散得到了很好的平衡。获得了一个体积仅为100 的成像光谱仪，其在VNIR波段的光谱分辨率为1.45纳米，在SWIR波段为2.40纳米。它在宽带空间探索方面具有巨大潜力。
