Du Liang-liang, Du Xue-wei, Li Chao-yang, An Ning, Wang Qiu-ping
Guang Pu Xue Yu Guang Pu Fen Xi. 2015 Jun;35(6):1751-5.
As an important optical splitting element, grating is used in many different spectrometers and spectrographs. Spherical 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 instruments. 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 x 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.
作为一种重要的分光元件，光栅被应用于许多不同的光谱仪和摄谱仪中。球面变线间距光栅（SVLSG）易于与阵列探测器结合，能够一次性获得宽波长范围的光谱，因为它可以将光谱聚焦在近似一个平面内。因此，它在许多光谱仪器中得到广泛应用。我们通常只知道商业光栅的中心刻线密度及其安装参数，而其线间距参数是未知的。此外，安装参数是在光栅的整个使用波长范围内进行优化的。然而，在大多数情况下，只使用了部分波长范围。所以，安装参数并未针对所需波长范围进行优化。在此条件下，本文基于平场光栅的聚焦理论以及制造商提供的安装参数，开发了一种方法来推导光栅的线间距参数。利用这些参数，我们可以根据所需波长范围优化探测器位置，并通过光线追迹来测试光学系统。本文研制了一台高光谱分辨率紫外摄谱仪，覆盖波长范围为230 - 280 nm。该摄谱仪中使用的光栅中心刻线密度为1200线×mm⁻¹，设计波长范围为170 - 500 nm。我们推导了光栅的线间距参数并优化了探测器安装参数。使用不同元素的空心阴极灯对摄谱仪进行校准并测试其光谱分辨率。采用参数拟合方法对摄谱仪进行了波长校准，校准精度优于0.01 nm。结果表明，该光谱仪在280.20 nm处的光谱分辨率约为0.08 nm。
