大口径光谱系统狭缝弯曲的分析与矫正

Analysis and Correction of Slit Curvature in Spectrograph with High NA

随着大口径光谱仪的发展,传统光谱仪中并不明显的狭缝弯曲越来越成为制约光谱仪分辨率的一大因素。根据由离轴光线光栅方程获得的偏移量公式对狭缝弯曲进行矫正。为消除公式与实际图像不契合的问题,详细分析了各装配误差对公式的影响,总结出相关矫正参数,并利用光谱线丰富的光源拟合出相关预矫正参数来消除装配误差造成的影响,再结合偏移量公式对待处理光谱图像进行矫正。利用氖光谱灯拟合预矫正参数,对氪光谱灯与汞蒸汽荧光灯进行了光谱测试,经矫正后光谱分辨率有很大改善,接近于光谱仪点源照射时的分辨率。

Slit curvature becomes an important factor which introduces the decline of spectral resolution in the developing of spectrograph with high NA. Slit curvature is corrected according to the correction formula obtained from the grating equation of off-axis ray. To cope with the problem that the real image of spectral lines usually deviate from the formula at ideal condition, Calibration with a spectral lamp which has lines distributed across the full span of the spectrograph is used to fit out the assembly error parameters. Neon lamp is used to fit out these parameters, slit curvature in the spectral image of krypton lamp and fluorescent lamp of mercury vapor is corrected with these parameters. Resolution has be significantly improved, which is nearly close to the spectral resolution limit of the spectrograph when irradiated by a spot light source.