基于光声光谱技术的NO,NO2气体分析仪研究

NO, NO₂是大气污染源中的常见气体, 对环境具有严重的危害性. 为检测污染源中这两种气体的浓度, 构建了成本较低的基于红外热辐射光源的光声光谱气体检测系统. 分析计算得到了NO, NO₂ 在2500–6667 nm波段吸收谱线. 通过建立光声传输线RLC振荡电路模型和仿真得到品质因数、声压大小与谐振腔长、内腔半径以及调制频率的关系, 据此设计了光声池几何结构. 实验表明该系统所测得的光声信号与气体浓度有很好的线性关系, 并且对NO, NO₂气体极限检测灵敏度分别达到4.01 和1.07 μL. 通过调节激光发射波长和选取滤波片, 该系统还可用于其他微量气体的浓度检测. 关键词： 大气污染 光声光谱 气体检测

Gas measurement system of NO and NO2 based on photoacoustic spectroscopy

NO and NO₂ are the common gases and have serious harmfulness to the atmosphere pollution of environment. To detect the concentration of the two gases in pollution, we construct a low cost photoacoustic spectrum gas measurement system based on the thermal radiation light source. Absorption lines of the NO and NO₂ between 2500 and 6667 nm are calculated. By modeling the photoacoustic transmission line the relations between quality factor, acoustic pressure and cavity length, cavity radius, modulation frequency are obtained, and the design of geometric construction of photoacoustic cell is also guided. The experiment show that there exists a good linearity between photoacoutic signal detected in the system and gas concentration, and the system ultimate detection sensitivities to the NO and NO₂ are 4.01 and 1.07 μL/L respectively. When the emission wavelength of laser is regulated suitably and the edmund optics is chosen reasonably, this system is also suitable for the concentration-detection of other trace gas.
Keywords： atmospheric pollution photoacoustic spectroscopy gas measurement