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为满足红外双光栅光谱仪波长重复性±0.05nm的指标要求,设计了光谱仪的波长扫描机构,分析了影响波长重复性的误差源。根据光谱仪结构特点和指标要求,设计了基于丝杠和摆杆的正弦机构作为波长扫描机构,依据凹面光栅扫描原理,推导了光机参数转换公式,分析了各误差源对波长扫描机构的影响。分析结果表明,在丝杠重复定位精度为±1.2μm时,光谱仪在760~2200nm波段范围内的重复性应优于±0.05nm。设计了红外双光栅光谱仪原理样机,并进行了实验验证。以汞灯为光源对其多个特征波长进行7次扫描,计算波长扫描机构在特征波长处的波长重复性。实验结果表明,光谱仪的波长重复性为-0.038~0.041nm,波长扫描机构满足使用要求。
In order to meet the index requirement of wavelength repeatability ± 0.05nm for infrared double grating spectrometer, the wavelength scanning mechanism of the spectrometer was designed and the error sources that affected the wavelength repeatability were analyzed. According to the structure characteristics and index of the spectrometer, a sine mechanism based on screw and pendulum was designed as a wavelength scanning mechanism. According to the principle of concave grating scanning, the formula of light machine parameter conversion was derived and the influence of each error source on the wavelength scanning mechanism was analyzed. The analysis results show that the repeatability of the spectrometer in the range of 760 ~ 2200nm should be better than ± 0.05nm when the repeatability of lead screw is ± 1.2μm. The principle prototype of infrared double grating spectrometer was designed and verified experimentally. A mercury lamp was used as a light source to scan several characteristic wavelengths for seven times, and the wavelength repeatability of the wavelength scanning mechanism at the characteristic wavelength was calculated. The experimental results show that the wavelength repeatability of the spectrometer is -0.038 ~ 0.041nm, and the wavelength scanning mechanism meets the requirements of use.