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凸面闪耀光栅是研制高光谱分辨率成像光谱仪的关键元件之一,一般凸面闪耀光栅的有效波段范围较窄,较难满足宽波段成像光谱仪对光栅衍射效率的需求。为拓宽仪器观测波段,对其中凸面闪耀光栅进行了优化设计。以0.4~2.5μm波段Offner型成像光谱仪为例,研究了凸面光栅单衍射级和双衍射级共路两种色散结构,采用分区闪耀光栅和双角闪耀光栅来提高宽波段范围内的衍射效率。优化设计了两种双闪耀光栅在不同色散结构下的槽形,用标量理论和有限元分析等方法对光栅衍射效率进行了计算。结合仪器信噪比,给出了满足成像光谱仪不同需求时所适用的光栅。
The convex blazed grating is one of the key components in the development of hyperspectral imaging spectrometer. The range of the effective blazed grating is narrow, which makes it difficult to meet the requirement of grating diffraction efficiency of wideband imaging spectrometer. In order to broaden the observation band of the instrument, the convex blazed grating was optimized. Taking the 0.4 ~ 2.5μm Offner imaging spectrometer as an example, two kinds of dispersive structures are studied, which are single diffraction order and double diffraction order of the gratings. Partition blazed gratings and double-angle blazed gratings are used to improve the diffraction efficiency over a wide wavelength range. The groove shapes of two double blazed gratings under different dispersion structures were optimized. The diffraction efficiencies of gratings were calculated by using scalar theory and finite element analysis. Combined with the signal to noise ratio of the instrument, the grating suitable for the different needs of the imaging spectrometer is given.