研究了一种在近红外波段具备良好成像能力的双凹面光栅成像光谱仪系统。对这种串联光栅系统中存在的主要像差像散和彗差进行了分析, 并计算获得了该系统的最优成像条件: 两个光栅和柱面透镜的最优摆放位置。这种改进型的Wadsworth系统可以在全波段近似消除彗差和像散, 具备良好的光学成像质量, 并仅通过刻线密度较低的光栅即可实现高光谱分辨率。设计了一个工作于780~1 100 nm波段的成像光谱仪系统, 其光谱采样达到0.92 nm/pixel, 全视场调制传递函数在17 lp/mm的奈奎斯特频率下高于0.45, 系统像差得到充分校正, 且加工和装调公差比较宽松。研究结果分析证明了设计理论的正确性。

A dual concave gratings imaging spectrometer with excellent imaging ability in near infrared waveband has been presented. The main aberrations as astigmatism and coma have been analyzed existing in this tandem gratings system. By calculating, the best imaging conditions, the optimal arrangements of gratings and adding cylindrical lens, were obtained. The advanced Wadsworth mounting could eliminate coma and astigmatism in the wide waveband and realize the high imaging quality. It could also realize the high spectral resolution with low ruling density gratings. A designed example presented excellent optical performances, the spectral sampling was 0.92 nm per pixel and modulation transfer function in all fields of views were higher than 0.45 in the Nyquist frequency at 17 lp/mm over the waveband from 780 nm to 1 100 nm. The aberrations of the system were corrected and the tolerances were loose. The results analysis proves the principle of design.