高光谱分辨率紫外平场光谱仪的研制

摘要

光栅作为一重要的分光元件，广泛应用于各类光谱仪，其中球面变线距平场光栅以其独特的平场特性使其容易与阵列探测器结合使用，一次实现宽光谱范围的记录。商业球面平场光栅一般只会提供光栅的公称线密度以及相应的安装参数，而不会提供光栅具体的变线距参数，并且提供的安装参数是针对整个使用波段优化的结果。使用者往往只需要其中的一部分波段。针对这种情况，根据球面平场光栅聚焦、分光原理，利用生产厂家提供的光学元件安装参数给出了推导球面变线距光栅变线距参数的方法。并给出了利用这些参数，根据光谱仪的实际工作波段确定最佳的CCD安装位置的方法。根据推导的光栅变线距参数可以对光学系统进行光学追迹已验证光学系统的性能。研制了一台高分辨率紫外平场光谱仪，覆盖光谱范围230～280 nm。采用的球面变线距光栅公称线密度为1200 lines・mm －1，使用波段为170～500 nm。推导了该光栅的变线距参数，并针对230～280 nm波段对CCD的安装位置进行了优化。同时利用不同元素的标准光源空心阴极灯对光谱仪进行了波长标定和光谱分辨率测试。波长标定采用参数拟合法，整个波段范围内的标定精度优于0.01 nm。光谱分辨率测试的结果表明光谱仪的光谱分辨率达到0.08 nm＠280.20 nm。%As an important optical splitting element ,grating is used in many different spectrometers and spectrographs .Spheri‐cal varied‐line‐spacing grating (SVLSG) is easily combined with array detectors to get a wide wavelength range of spectrums in one time ,because it can focus the spectrums in approximately a plane .Therefore ,it’s widely used in many spectral instru‐ments .We usually only know the central groove density of a commercial grating and its mounting parameters ,while its line spacing parameters are unknown .Moreover ,the mounting parameters are optimized within the whole using wavelength range of the grating .However ,in most circumstances only part of the wavelength range is used .Therefore ,the mounting parameters are not optimized for the needed wavelength range .Under this condition ,in this article we developed a method based on the focusing theory of the flat‐field grating and the mounting parameters the manufacture provided to deduce the line spacing parameters of the grating .With these parameters ,we can optimize the detector position according to the wavelength range we need and ray tracing can be done to test the optical system .In this article we developed a high spectral resolution ultraviolet spectrograph , covering a wavelength range of 230~280 nm .The grating used in this spectrograph has a central groove density of 1 200 lines・mm-1 and a designed wavelength range of 170~500 nm .We deduced the line spacing parameters of the grating and optimized the detector mounting parameters .Hollow cathode lamps of different elements were used to calibrate the spectrograph and test the spectral resolution of it .Wavelength calibration of the spectrograph has been done with the parameter fitting method ,and the calibration accuracy is better than 0.01 nm .Results show the spectral resolution of the spectral graph is about 0.08 nm at 280. 20 nm .