可调谐激光吸收光谱学检测甲烷浓度的新方案研究.pdfVIP

学兔兔 第31卷 第11期 仪 器 仪 表 学 报 V01．31 No．1l 2010年11月 Chinese Journal of Scientific Instrument NOV．2010 可调谐激光吸收光谱学检测甲烷浓度的新方案研究 曹家年，张可可，王 琢 (哈尔滨工程大学信息与通信工程学院 哈尔滨 150001) 摘 要：基于可调谐二极管激光吸收光谱的光纤气体传感器检测气体浓度，具有灵敏度高、选择性好、响应时间快等优点。目 前报导的基于二次谐波的气体浓度检测系统，普遍采用一次、二次谐波幅值之比作为系统输出，消除光强波动的影响。研究中 分析了二次谐波检测方案的特点与不足，提出利用一次谐波检测甲烷的浓度，以一次谐波峰峰值与平均值的比值作为系统输 出，系统结构简单，并可抑制光源波长漂移和扫描步长等因素对系统检测精度的影响。实验结果表明甲烷的浓度与系统输出值 之间具有很好的线性关系，其线性拟合系数为0．999，系统的分辨率和检测精度分别为20 X 10 和100×10一。 关键词：光纤气体传感器；可调谐二极管激光吸收光谱；波长漂移；扫描步长 中图分类号：TN247 文献标识码：A 国家标准学科分类代码：140．3025 New scheme of methane concentration detection with tunable diode laser absorption spectroscopy Cao Jianian，Zhang Keke，Wang Zhuo (College ofInformation and Communication Engineering，Harbin Engineering University，Harbin 150001，China) Abstract：Optical fiber gas sensor based on tunable diode laser absorption spectroscopy(TDLAS)is used to meas— ure gas concentration，which has the advantages of high—sensitivity，good—selectivity and fast—response time and etc． Currently reported second harmonic concentration detection system uses the ratio of first and second harmonic ampli— tudes as the system output to eliminate the influence of optical intensity fluctuations．This paper analyzes the charac— teristics and shortcomings of this method and proposes a new method，which uses first harmonic signal to measure methane concentration．Th e proposed first harmonic detection system uses the ratio of first harm onic peak—peak value and its average value as the system output，which has a simple structure and inhibits the influence of laser wave— length shift and scanning step length．Experiment results show that there is a good linea