The Detection of CO Based on TDLAS Combined with Balanced Difference Detection Technology
LI Chuan-liang1*, JIANG Li-jun1, SHAO Li-gang1, GUO Xin-qian1, QIU Xuan-bing1, WEI Ji-lin1, GAO Rui1, WANG Gao2
1. School of Applied Science, Taiyuan University of Science and Technology, Taiyuan 030024, China
2. Key Laboratory of Science and Technology on Electronic Test and Measurement, North University of China, Taiyuan 030051, China
Abstract：The P(4) line of 3-0 band for CO gas in different pressures and concentrations was measured by employing tunable diode laser absorption spectroscopy combined with balanced difference detection technology. Due to the immunization to the common-mode noise of fluctuation of laser intensity, drifts of temperature and mechanical vibrations, the sensitivity of spectroscopy can be improved by balanced difference detection technology. In comparison with the direct absorption spectroscopy (DAS), the signal to noise ratio was improved by 3.4 times, and the minimum detection limit (MDL) reached 87 ppmv. The optimum pressure for CO was 70 Torr through comparing the spectral signals at 40 Torr, 55 Torr, 70 Torr and 85 Torr of 1% CO concentration. Moreover, different concentrations of CO at 70 Torr were detected by DAS and balanced difference detection, and the results demonstrated the balanced difference detection had a more linear relationship and the deviation was less than 5%. For further testification of the stability of the system, we collected the signals within 360 s for the Allan variance analysis, which denoted the most suitable detection time was 38 s and the MDL was 47.8 ppmv.
Key words：Tunable diode laser absorption spectroscopy; Balanced difference detection; Detection of CO
李传亮，蒋利军，邵李刚，郭心骞，邱选兵，魏计林，高 睿，王 高. 基于TDLAS平衡差分技术的CO气体检测[J]. 光谱学与光谱分析, 2017, 37(10): 3165-3169.
LI Chuan-liang, JIANG Li-jun, SHAO Li-gang, GUO Xin-qian, QIU Xuan-bing, WEI Ji-lin, GAO Rui, WANG Gao. The Detection of CO Based on TDLAS Combined with Balanced Difference Detection Technology. SPECTROSCOPY AND SPECTRAL ANALYSIS, 2017, 37(10): 3165-3169.
