宽光谱Czerny-Turner光谱仪中的彗差与分辨率

Coma and Resolution in Wide Spectral Region Czerny-Turner Spectrometer

小型光谱仪较多地采用Czerny-Turner(切尼—特纳)光路结构,其设计应遵循Shafer消彗差原理消除中心波长处的初级彗差并尽量平直整个谱面以提高分辨率。但常规设计并未考虑非中心波长处彗差和分辨率的变化情况。在对两种典型切尼—特纳光路结构进行初级彗差分析的基础上,指出交叉型光路结构宽光谱范围内的分辨率呈"V"形,而M型光路结构分辨率在全光谱范围内变化较小,近似呈"一"形,即后者宽光谱范围内的分辨率一致性远好于前者。针对于此,该文设计了光谱范围为400～600nm的2种光路,并对其进行了理论计算和对比实验,实验结果表明,两者边缘波长处分辨率分别比中心波长处分辨率低3.7倍和1.2倍,与理论计算结果基本一致。

The Czerny-Turner layout,which is most frequently used in miniature spectrometers,should follow Shafer’s coma-free condition and Fastie’s flat-field principal to eliminate the central wave’s primary coma and maximize its resolution.However,the design process does not take the comas and resolutions at non-central waves into consideration.Based on the theory of primary coma in reflection optical system,the present paper points out that in the crossed beam design,the resolutions at wide spectral region present a ＂V＂ shape,while in the M design,the resolutions change little over the whole region,and present an approximately straight line shape,so the latter kind of spectrometer maintains a far more consistent resolution than the former one.Accordingly,this paper designs two kinds of spectrometers with spectrum regions from 400 to 600 nm,and carries out theoretical simulation and contrast experiment.The result demonstrates that for the two designs the resolutions at the fringe wavelength are 3.8 times and 1.5 times respectively that at the central wavelength,which accords with the conclusion of the theoretical simulation.