平板波导光谱仪中光栅多次衍射杂散光的抑制

平板波导光谱仪是一种紧凑型光谱仪，其光栅多次衍射杂散光大，需要进行抑制。首先研究了多次衍射杂散光的形成过程，并通过TracePro软件详细分析了多次衍射杂散光的传播路径和大小。然后根据杂散光的空间特性和波长特性对其进行分类，采取不同的抑制方法。在不改变原有光学结构的基础上提出了利用滤光片和挡光板来抑制多次衍射杂散光的方法，滤光片的参数和位置需要精心选择以达到最好的抑制效果。最后对增加抑制结构前后的杂光系数进行对比分析。结果表明，多次衍射杂散光得到了很好的抑制，最大杂光系数从5.3%降到0.033%，平均杂光系数从1.9%降到0.0018%。

Suppression of grating multiply diffracted light in planar waveguide spectrometer

Planar waveguide spectrometer is a compact spectrometer, which has an asymmetrical crossed Czerny-Turner optical structure within a planar waveguide structure. The multiply diffracted light of this spectrometer is large, so it needs to be carefully studied in order to find a suitable method to reduce it. The formed of the multiply diffracted light could be derived from the diffraction characteristic of grating. Then the stray light problem was identified by using the TracePro software. Then based on the difference of the spatial property and wavelength of stray light, different suppression methods were used. Filters and baffles were involved to suppress the multiply diffracted light, without changing the original optical structure. Finally, stray light coefficient was introduced to evaluate the effect using stray light suppression structure. Simulation and analysis results show that the multiply diffraction light of spectrometer has been well suppressed. The maximum of the stray light coefficient is reduced form 5.3% to 0.033%, and the average of it is dropped from 1.9% to 0.0018%.