小型高光谱分辨率光栅单色仪的研制

Research on Small-Type and High-Spectral-Resolution Grating Monochromator

单色仪是成像光谱仪进行光谱连续定标的必备设备,为了对高光谱成像光谱仪进行连续光谱定标,设计了一种轻小型高光谱分辨率的光栅单色仪。采用水平式Czerny-Turner光路结构,以高光谱分辨率为出发点,通过推导计算,从光栅选型、焦距计算、狭缝尺寸的确定等方面详细论述了光栅单色仪的设计思路,给出仪器的重要必要结构参数,并论述了这些结构参数对仪器光谱分辨率和体积的影响。根据光栅单色仪的光路特点,对入射狭缝组件、准直物镜组件和成像物镜组件、扫描结构、机身等进行轻小型机械结构设计,并给出正弦杆扫描机构的结构参数与仪器输出波长和波长扫描精度的数学关系,完成了仪器的整体结构设计和装调。应用汞灯可见光光谱进行波长定标,采用最小二乘法得到定标曲线,并提出步进数极限误差与定标曲线相结合的方法,求得仪器的波长重复性和波长准确度;仪器在400~800nm波长范围内,光谱分辨率优于0.1nm,波长重复性达±0.096 6nm,波长准确度达±0.096 9nm。

Monochromator is the necessary equipment for spectral imager to calibrate the spectrum continuously.In order to calibrate the hyperspectral imaging spectrometer continuously,a small-type and high-spectral-resolution grating monochromator is designed.The grating monochromator with horizontal Czerny-Turner structure is designed with high-spectral-resolution as a starting point,and the design idea is discussed in detail from choosing the grating,calculating the focal length,the sizes of entrance slit and exit slit,among others.Using this method,the necessary structure parameters are determined,and the impact of the necessary structure parameters for spectral resolution and volume is given.According to the optical characteristics of the grating monochromator,the mechanical structures of the instrument are designed for small and handy from the components of the entrance slit,the collimator lens and imaging objective lens,the scanning structures,the fuselage and so on.The relationship of the sine mechanism parameters for output wavelength and wavelength scanning accuracy is given.The design and adjustment of the instrument are completed.The visible spectrums of mercury lamp are used as calibration lines,and the calibration curve is acquired by using least square method.This paper gives a method that combining the limit error of the step number and the calibration curve to evaluate the wavelength repeatability and wavelength precision.The datum of experiment shows that the spectral resolution of the instrument is better than 0.1nm in the wavelength band from 400 to 800nm.Simultaneously the wavelength repeatability reach to±0.096 6nm and the precision reach to±0.096 9nm.