紫外双光栅光谱仪结构设计与波长精度分析

为了满足太阳光谱在170～380 nm波段的精确观测需求,设计了波长重复性精度优于±0.02 nm的紫外双光栅光谱仪。波长扫描机构是双光栅光谱仪的关键组件,根据凹面光栅色散原理,将光学设计指标转换为波长扫描机构设计的输入参数,分析了影响光谱仪波长重复性精度的误差源。根据分析结果得知,丝杠的重复定位误差是影响波长重复性的主要误差源。选用重复定位精度为±2μm的丝杠设计了波长扫描机构,并对光谱仪整机进行了设计。以汞灯光源对光谱仪的波长重复性指标进行了验证实验。实验结果表明,设计的光谱仪波长重复性介于-0.005～+0.007 nm之间,满足波长重复性优于±0.02 nm的指标要求。

Structure design and wavelength accuracy analysis of ultraviolet double grating spectrometer

In order to observe the solar spectrum between 170 nm to 380 nm precisely, an ultraviolet double grating spectrometer with its wavelength repeatability accuracy better than ±0.02 nm has been designed. A wavelength scanning mechanism is the key module of the ultraviolet double grating spectrometer. Mechanical parameters are derived from optical parameters according to the grating dispersion principle. Error sources which influence the spectrometer wavelength repeatability error have been analyzed. According to the analysis results, the repeatability error of the lead screw is the main error source. A wavelength scanning mechanism has been assembled with a ±2 μm accuracy lead screw, and the spectrometer mechanism structure has been designed. Experiments have been carried out with a mercury lamp as light source to verify wavelength repeatability. The experiment results show that the wavelength repeatability of the spectrometer is between -0.005 nm and +0.007 nm, which is better than the required accuracy of ±0.02 nm.