利用宽带光源设计了用于探测甲烷浓度的光声光谱系统,在22 Hz最佳调制频率下对甲烷浓度进行了探测,利用Allan方差分析了系统的稳定性,评估了系统的最低探测浓度。研究结果表明,系统对甲烷浓度(体积比)的探测极限能达到1×10 ^-6。利用宽带光声光谱系统及基于分布反馈式二极管激光光源和长光程吸收池的直接吸收光谱探测系统同时对甲烷浓度进行探测,得到宽带光声光谱系统对甲烷浓度探测的误差约为8%。

A photoacoustic spectroscopy detection system based on a broadband light source is introduced, and the methane concentration is detected at the optimum modulation frequency of 22 Hz; further, the stability and the minimum detection concentration of the system are analyzed with Allan variance. The research results exhibit that the concentration (volume ratio) detection limit of methane can exceed 1 × 10 -6. The methane concentration is detected by broadband photoacoustic system and direct absorption detection system based on distributed feedback diode laser source with a long path absorption cell simultaneously. The detected results show that the error of methane concentration detection by the broadband photoacoustic system is about 8%.