Wavelet Denoising Research for the Tunable Laser Diode Absorption Spectroscopy of the CO at 1.578 μm
QIU Xuan-bing1, SUN Dong-yuan1, LI Chuan-liang1*, WU Ying-fa1, ZHANG En-hua1, WEI Ji-lin1, WANG Gao2*, YAN Yu3*
1. School of Applied Science, Taiyuan University of Science and Technology, Taiyuan 030024, China
2. State Key Laboratory for Electronic Test Technology, North University of China, Taiyuan 030051, China
3. Automobile Engineering Department, Hebei Vocational Education College of Industry, Shijiazhuang 050091, China
Abstract：The signals processing algorithm is presented based on laser spectroscopy direct absorption signal (DAS) and wavelength modulation spectroscopy (WMS) for the trace carbon monoxide (CO) measurement. The simulated transmittance data of the pure CO gas are from the HATRAN database. The DAS intensity, appending WMS 1-f and WMS 2-f signal intensities are used as the raw signals. Aimed to obtain optimized filtering algorithm, those raw signals which were added Gaussian white noise are denoised by using diverse wavelet-bases and decomposition layers. The effectiveness is validated by our CO concentration detection experiment which measures the weak laser absorption spectral line P(4) of second overtone band at 1.578 μm. A 0.95 m Herriott-type cell provides an effective absorption path length of 55.1 m. Comparing the sensing performances without and with using the optimized wavelet, the experimental results show that the signal-to-noise ratios of the system are significantly improved by 1 to 2 orders of magnitude for the DAS, 1-f and 2-f signal. The anti-jamming capability of the system is improved by proposing the suitable wavelet-base and decomposition layer algorithm.
Key words：Laser absorption spectroscopy; CO spectra at near-infrared; Wavelength modulation spectroscopy; Wavelet-denoising
邱选兵，孙冬远，李传亮，吴应发，张恩华，魏计林，王 高，鄢 玉. CO在1.578 μm的可调谐二极管激光光谱信号小波去噪研究[J]. 光谱学与光谱分析, 2019, 39(02): 628-633.
QIU Xuan-bing, SUN Dong-yuan, LI Chuan-liang, WU Ying-fa, ZHANG En-hua, WEI Ji-lin, WANG Gao, YAN Yu. Wavelet Denoising Research for the Tunable Laser Diode Absorption Spectroscopy of the CO at 1.578 μm. SPECTROSCOPY AND SPECTRAL ANALYSIS, 2019, 39(02): 628-633.
