介绍了一种近红外光谱烷烃类气体在线定量分析测量方法.该方法以单片闪耀光栅为核心构成分光系统,分析计算了分光系统的关键参数,设计构建了硬件系统平台,完成了窄带光束实验测试和烷烃类七种单组分气体光谱探测实验.实验表明,入射狭缝为2 mm时,分光系统在中心波长1 200～1 800 nm波段内能够分离谱宽为10 nm的窄带光束,出射光束中心波长步进扫描步长优于0.1 nm.光谱探测实验证实七种气体在1 600～1 800 nm波段内存在较强的特征谱线,但存在严重的交叉混叠现象.甲烷谱线位置与HITRAN光谱数据库相吻合.实验结果表明该方法有可能用于混合气体探测,且结构简单、成本低廉,为后续研究提供了技术储备并明确了研究方向.%A method for online quantitative analysis system of alkane gaseous mixture with near infrared spectroscopy is described in the present paper. A single plane diffraction grating is used as the principal device in the monochromatic spectrum system. The key parameters of the monochromator were deduced and calculated in detail A quantitative analysis system was designed and constructed according to the parameters. The narrow-band beam testing experiments and spectral scanning experiments of seven kinds of single-component alkane gases were accomplished on the above hardware system platform. The narrowbeam experiments show that a 10 nm narrow-band beam spectra was successfully obtained by the monochromatic system when the entrance slit width is 2 mm. And a step-scanning resolution of the outgoing beam's center wavelength with 0. 1 nm can be realized within the spectra of 1.2～1.8 μm. The spectral scanning experiments indicate that there was some stronger characteristic absorption spectrum existing between the spectra of 1.6 ～ 1.8 μm, which is consistent with the HITRAN spectral database.And there is serious cross-aliasing phenomenon existing among the absorption spectra. These experiments demonstrate that this method has a successful application in mixed gas monitoring and on-line analysis with the characteristics of simple structure and low cost. And it also provides further technical reserves and opens a path way to spectral analysis in the follow-up studies.
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