运用傅里叶变换对差分吸收光谱的解析  

Using Fourier Transform to Analyse Differential Optical Absorption Spectrum

作　　者：刘前林[1] 王立世[2] 黄新建[2] 

机构地区：[1]华南理工大学环境科学与工程学院,广东广州510640 [2]华南理工大学化学科学院,广东广州510640

出　　处：《光谱学与光谱分析》2008年第5期1076-1079,共4页Spectroscopy and Spectral Analysis

基　　金：国家自然科学基金项目(20475018);广东省科技计划项目(2005B33303001)资助

摘　　要：利用差分吸收光谱技术原理,设计了相应的差分吸收光谱监测装置,对环境中存在两种主要污染气体SO2和NO2进行了监测。在对所测光谱进行分析时,提出了用傅里叶变换的信号分析方法来解析上述两种气体的吸收光谱。在光谱分析过程中,主要包括光谱信号的去噪处理和慢变化的拟合两大步骤。差分吸收光谱仪所测到的原始光谱经傅里叶变换后,频谱中的低频部分对应的就是原始光谱中的慢变化部分,而噪声谱主要集中在变换后频谱的高频部分,所以可以通过截取一定频率段的频谱后再通过逆傅里叶变换来去除气体吸收光谱中的慢变换部分和噪声部分,进一步处理后可以得到气体的差分吸收光谱,从而反演计算出对应的气体浓度。通过分析比较,该方法是一种新的差分吸收光谱解析方法,可以更好地拟合出原始光谱中的慢变化部分,与此同时,在去除噪声影响,提高信噪比方面有很好的作用。According to the theory of differential optical absorption spectral technique, the differential optical absorption spectral monitoring equipment was designed. Aiming at two kinds of main pollutants, SO2 and NO2, in the atmosphere, this technique was used to monitor them. The present article puts forward the signal analysis method of Fourier transformation to process the above-mentioned two kinds of absorption spectra. The two approaches contain the removeal of noise and the fitting of the slow variety. On the frequency chart after the spectrum was transformed, the low frequency corresponded to the slow variety part and the high frequency corresponded to the noise part of the original spectrum, so through intercepting a certain frequency segment and using inverse Fourier transformation the slow variety part of the low frequency and the noise part of the high frequency of the absorption spectrum could be subtracted. After farther processing we can get a higher resolution differential absorption spectrum of the gas. According to the strength of the spectrum, we can calculate the concentration of the gas. After analysis and comparison with the conventional method, it is considered a new processing method of differential optical absorption spectral technique, and the method can fit the slow variety much better.

关 键 词：傅里叶变换 差分吸收光谱技术 信噪比 光谱分析 

分 类 号：X831[环境科学与工程—环境工程]