【作者】 田庆国；

【导师】 王玉田；

【作者基本信息】 燕山大学 ， 测试计量技术及仪器， 2004， 硕士

【摘要】 随着工业现代化和人民生活水平的提高，现代社会对石油和煤炭燃料的需求量不断提高，但由于设备工艺和燃烧方式的落后，有愈来愈多的有害气体排放到大气当中，给人民生活和工农业生产带来日益严重的危害。因此，研制一种能够实时监测、高灵敏度、高分辨率的气体浓度传感器用于监测有害气体浓度不仅具有理论意义，更有服务国民经济，改善人民生活的现实意义。本文在分析各种气体浓度检测方法的主要优缺点的基础上，选择二氧化硫(SO2)作为研究对象，研究一种应用光声光谱原理和光纤光相位调制机理相结合的气体浓度监测仪。本文从分子结构和分子光谱理论出发讨论了SO2的红外光谱结构，介绍了气体光声光谱检测理论及光纤光相位调制解调的技术和方法。文中详细讨论了光纤光声SO2气体浓度监测仪的硬件设计。谐振式光声腔的设计是该系统的关键，包括光声腔结构设计、第一谐振频率及品质因子的确定、光学反射装置、光纤和光声腔的耦合等。选用一氧化碳(CO)激光器作为激励光源，讨论了CO激光器的结构和机械斩波技术。光纤相位传感器使用激光二极管作为光源，讨论了光源、光纤和光接收器件的连接方法以及激光二极管的光源驱动电路的设计。本文在讨论了光电二极管的噪声和等效电路之后，介绍了信号处理的技术和方法，包括前置放大器、差分放大器和有源带通滤波器的设计及用于微弱信号检测的锁相放大技术。通过软件设计使数据处理智能化。本文最后以实验样机为对象进行试验研究，包括光路损耗实验、气体浓度和输出信号的关系实验以及系统的重复性和稳定性等实验。从而验证了气体光声光谱检测原理和光纤相位传感器相结合进行气体浓度检测的可行性。更多还原

【Abstract】 With the modernization of industry and the improvement of people’s life, the consumption of fossil fuel, such as petroleum and coal, is being increased. Because of the equipment and combustion methods, more and more baneful gases are released into the air, which are harmful to people’s health and life. Based on this fact, researching and manufacture a kind of new gas sensor with high sensitivity and real-time detection has an important theoretic and realistic significance.After comparing main advantage and disadvantage of all theories of gas concentration measurement, this thesis chooses SO2 as object to research a kind of SO2 concentration measurement apparatus on the base of theory of photoacoustic effect and the optical fiber phase modulated mechanism.Firstly, this paper introduces the molecule’s structure, the molecule’s spectrum and infrared spectrum structure of SO2, and then the theory of gas detection using photoacoustic effect is discussed. The design of resonant P.A. cell is one of the most important parts, including P.A. cell structure, first resonance frequency, optical reflection sets, and couple between optical fiber and P.A. cell, etc. Using CO laser as incentive source has many advantages, and optical modulating is discussed.After pin’s noise and equivalent circuit are discussed, this thesis introduces technology and methods of signal management, including pre-amplifier and differential-amplifier, BPF, LIA, etc.At the end of paper, the system of photoacoustic spectrometer is proved by experiment.更多还原