应用超窄线宽半导体激光器的波长扫描和光谱调制技术, 设计了一种高精度多组分气体实时在线检测系统。系统采用单一超窄线宽可调谐半导体激光器作为光源, 设计了新型串联式气室结构减小横向空间、增加光程长, 并通过三角波信号对光源光谱进行调制; 结合时分复用和空分复用技术, 利用超窄线宽激光的特性实现了CO, CO2, CH4多组分气体浓度的同时多点检测。实验结果表明, 对CO, CO2, CH4多组分气体浓度测量的线性相关度为0.99, 最大相对误差<2%; 逐次充入一定体积CH4, CO2, CO气体, 动态响应时间均小于10 s。长时间稳定性实验显示, 多组分气体浓度最大波动<0.02%。该系统精确度高、稳定性好, 具有较好的动态响应特性, 可用于电力变压器故障气体的实时在线监测。

On the basis of the wavelength scanning and spectrum modulation techniques of an ultra-narrow-linewidth semiconductor laser, a kind of multi-component gas online detection system with high precision was designed. A semiconductor laser with ultra-narrow-bandwidth and tunable wavelength was utilized as a light source and a novel series gas cell was also used to compress the horizontal space and increase the optical path of the system. By taking the sawtooth signal to modulate the spectrum of laser and using space division multiplexing (SDM) and time division multiplexing (TDM) techniques, the detection of multi-component gases(CO, CO2, CH4) based on ultra-narrow-linewidth laser characteristics was achieved. The experiments indicate that the relative measurement error is less than 2% and linearity relevance coefficient is 0.99 for the three kinds of gases. Furthermore, the system dynamic response time is less than 10 s by filling a volume of multi-component gas into the gas cell gradually. Finally, the result of long time stability monitoring shows that the maximum concentration fluctuation is less than 0.02%. The system has advantages of high accuracy, good stability and quick response, and is suitable for the fault gas monitoring of power transformers in real time.