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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1.07μL.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.
NO and NO2 are common gases in air pollution sources, which have serious harm to the environment.In order to detect the concentrations of these two gases in the pollution sources, a low-cost photoacoustic spectroscopy gas detection system based on infrared heat radiation light source is constructed. The absorption spectra of NO and NO2 in the wavelength band of 2500-6667 nm were calculated.The quality factor, the relationship between the sound pressure and the cavity length, the cavity radius and the modulation frequency were obtained through the model and simulation of the RLC oscillation circuit of the photoacoustic transmission line The geometrical structure of the photoacoustic cell is designed.The experimental results show that there is a good linear relationship between the photoacoustic signal and the gas concentration measured by the system, and the sensitivities of NO and NO2 gas detection limit are 4.01 and 1.07μL, respectively. By adjusting the laser emission wavelength And select the filter, the system can also be used for the concentration of other trace gases detection.