改进型Czerny-Turner成像光谱仪光学系统设计方法

Design Method of Optical System of Improved Czerny-Turner Imaging Spectrometer

像散是目前影响Czerny-Turner结构成像光谱仪空间分辨率最大的像差。首先引入柱面反射镜,利用光焦度衡量像散大小,推导出易于计算的像散校正公式,有效地校正了像散。给出准直镜到光栅距离的计算方法,有效校正了成像光谱仪边缘视场像差。给出了成像光谱仪像面倾角的计算方法,实现了宽波段的像差校正。最终利用上述方法设计了一套用于115～200nm的改进型Czerny-Turner成像光谱仪,焦距f′=48mm,F数为5.0,全视场、全波段调制传递函数(MTF)在0.7以上。全波段光谱分辨率为0.22nm,像面大小为8mm×7mm。设计方法适用于多种结构要求的成像光谱仪。

Astigmatism is the main aberration that limits the spatial resolution of Czerny-Turner imaging spectrometer. Focal power is introduced to calculate astigmatism, and formulas are deduced to correct it, The method of computing the distance between grating and collimator is given, which is able to correct the aberration of the edge of field of view. The computing method of tilt angle of imaging plane, which is helpful to correct the aberration at all wavelengths. And an imaging spectrometer based on such structure working in 115 - 200 nm is designed, with f^1=48 ram, F number is 5.0 and image size is 8 minx 7 mm. The designed imaging spectrometer can get spectral resolution δλ = 0.22 nm and modulation transimission function （MTF） is 0.7 at all wavelengths and full field of view. The design method can be applied to other imaging spectrometers of different strtmmres.