激光与光电子学进展, 2018, 55 (3): 033002, 网络出版: 2018-09-10
基于可调谐半导体激光吸收光谱的小型化C2H2测量系统 下载: 1255次
Compact Acetylene Detecting System Based on Tunable Diode Laser Absorption Spectroscopy
光谱学 C2H2气体检测仪 可调谐半导体激光吸收光谱 波长调制-多光程吸收技术 检测灵敏度 小型化 spectroscopy detecting instrument of acetylene tunable diode laser absorption spectroscopy wavelength modulation-multi-pass absorption techni detecting sensitivity compact
摘要
基于可调谐半导体激光吸收光谱技术,研制了一套近红外波段的乙炔(C2H2)气体检测系统,该装置采用波长调制-多光程吸收光谱技术,提高了系统的检测灵敏度;为了优化系统测量条件,在压强范围为5.3~12.0 kPa和调制幅度为0.010~0.035 V条件下,测量了体积分数为5×10
-5的C2H2标准气体的光谱信号,并测量了不同浓度的C2H2在总压强为10.7 kPa时的二次谐波信号;为了进一步验证系统的稳定性,采集60 s的光谱信号,通过Allan方差分析获得了系统的最佳探测时间和探测极限。结果表明:压强为10.7 kPa且调制幅度为0.030 V时的二次谐波信号强度最大;C2H2气体浓度与二次谐波幅值呈良好的线性关系,并且C2H2体积分数为1×10
-6~5×10
-5时的测量误差较小,小于±2%;该实验系统的最佳探测时间为7.2 s,探测极限为2.8×10
-11;该仪器采用基于嵌入式系统设计的激光器驱动和数字锁相放大器,具有结构简单、体积小、便于集成等特点,适用于工业现场和气体运输等方面。
Abstract
A detecting system of acetylene (C2H2) gas in near-infrared region is developed based on the tunable diode laser absorption spectroscopy. The wavelength modulation spectroscopy in combination of multi-pass absorption cell is used to improve detecting sensitivity of the system. To optimize detecting conditions of the system, spectral signals of standard C2H2 gas with volume fraction of 5×10
-5 are detected under the conditions of pressure of 5.3-12.0 kPa and modulated amplitude of 0.010-0.035 V. The second harmonic signals of C2H2 with different concentrations are detected at the total pressure of 10.7 kPa. To verify stability of the system, spectral signals for 60 s are acquired, and the most suitable detection time as well as the minimum detection limit is obtained by the Allan variance analysis. The results show that the signal intensity of the second harmonic signals is the greatest at pressure of 10.7 kPa and modulation amplitude of 0.030 V. The volume fraction of C2H2 is with a good linear relationship with the amplitude of the second harmonic signals, and the detecting deviation is less than ±2% in the range of volume fraction from 1×10
-6 to 5×10
-5. The most suitable detection time of the experimental system is 7.2 s, and the minimum detection limit is 2.8×10
-11. The instrument adopts a laser driver and a digital lock-in amplifier based on an embedded system, so the instrument has the characteristics of simple mechanical structure, small size, and easy integration with other systems. Therefore, the compact detecting system for C2H2 gas is suitable for industrial process and gas transmission.
蒋利军, 邱选兵, 周庆红, 邵李刚, 杨雯, 魏计林, 李传亮, 马维光. 基于可调谐半导体激光吸收光谱的小型化C2H2测量系统[J]. 激光与光电子学进展, 2018, 55(3): 033002. Lijun Jiang, Xuanbing Qiu, Qinghong Zhou, Ligang Shao, Wen Yang, Jilin Wei, Chuanliang Li, Weiguang Ma. Compact Acetylene Detecting System Based on Tunable Diode Laser Absorption Spectroscopy[J]. Laser & Optoelectronics Progress, 2018, 55(3): 033002.