离轴石英谐振光声光谱CO_2传感研究

Detection of carbon dioxide based off-beam quartz enhanced photoacoustic spectroscopy

二氧化碳(CO_2)不仅是一种重要的温室气体,也是具有危害性的窒息性气体,因此发展小型化、高灵敏度的CO_2浓度传感器对无人机载、探空球等探测大气CO_2以及在空间封闭环境的CO_2浓度监测等领域具有较大的应用需求。开展了基于2.0μm可调谐半导体激光器的CO_2传感研究,搭建了CO_2探测实验系统。系统以4989.97 cm^(-1)处的CO_2吸收谱线为研究对象,采用微小型离轴石英音叉增强型光声光谱新技术对CO_2气体传感进行研究。通过优化调制频率和调制振幅等参数,确定了CO_2传感系统的最佳参数。在最优实验参数条件下对CO_2气体进行探测,获得系统的最小探测灵敏度为142μL/L,最小归一化等效噪声吸收系数为3.37×10^(-8)cm^(-1)W/Hz^(1/2)。

Carbon dioxide(CO2) is not only an important greenhouse gas, but also a harmful asphyxiating gas. Therefore, the development of miniaturized, high-sensitivity concentration sensor of CO2 has great application requirements for detecting atmospheric CO2 by unmanned aerial vehicles, sounding balloons,and monitoring CO2 concentration in space-enclosed environments. An experimented setup based on 2.0 μm tunable semiconductor laser was established for the detection of CO2 concentration. The CO2 absorption line at 4989.97 cm^-1 was chosen as the target line, and the CO2 gas sensing was carried out using microminiature off-beam quartz enhanced photoacoustic spectroscopy. By detecting the photoacoustic signals of a certain concentration of CO2 at different modulation frequencies and modulation amplitudes, the optimal modulation frequency and modulation amplitude of the system were obtained. The CO2 gas is detected under the optimized parameters,a detection limit of 142 μL/L is achieved, which corresponds to a normalized noise equivalent absorption coefficient of 3.37×10^-8cm^-1W/Hz^1/2.