1. Chongqing Research Institute of China Coal Technology & Engineering Group Corp. ,Chongqing　 400039,China; 2. National Key Lab for Gas Disaster Monitoring and Emergency Technology,Chongqing　 400037,China

为保证激光甲烷检测系统的长期稳定性,实现自动校准功能,同时大幅降低点式激光甲烷系统的成本,采用激光自稳频技术研发分布式多点激光甲烷检测系统。通过软硬件结合的方式实现激光自稳频,采用1/8光分束器将激光器出射光波分为8路,其中一路引入密封有恒定甲烷气体的参考气室,通过实时信号采集和处理得到甲烷吸收信号的二次谐波波形,提取出光波中心波长λ1和工作范围Δλ1,再通过闭环负反馈控制链路对激光器驱动电流进行自动调节。实验结果表明:在吸收波形中心位置处,波长控制精度达到0.000 1 nm,中心波长波动范围由1 653.697 51 653.749 6 nm减小至1 653.723 41 653.723 6 nm,波长工作光谱范围变化由0.138 10.159 6 nm减小至0.149 50.150 8 nm,将系统检测误差由原来的±4%减小至±0.5%;基于激光自稳频技术设计的分布式多点激光甲烷系统,能够实现多个测点甲烷的实时监测,其测量误差≤1%。采用激光自稳频技术,可以实现系统中工作波长的精确控制,进而保证激光甲烷检测系统在环境温度变化、器件老化等过程中性能的长期稳定性。

In order to ensure the long-term stability of laser methane detection system, achieve automatic calibrate function and significantly reduce the cost of point laser methane system,the distributed multi-point laser methane de- tection system by laser self-stabilizing technology was developed. Through the combination of hardware and software to achieve laser self-stabilizing technology,1 / 8 optical beam splitter was used to divide the light emitted by the laser into 8 channels,in which a reference chamber with constant methane gas was introduced. The second harmonic waveform of methane absorptive signal was obtained by real-time signal acquiring and processing. The wavelength and working range of laser wave were extracted. And then through the closed-loop negative feedback control link on the laser drive current automatically adjusted. Experimental results show that at the center of absorptive waveform,the wavelength control accuracy is 0. 000 1 nm,the wavelength fluctuating range from 1 653. 697 5-1 653. 749 6 nm is reduced to 1 653. 723 4-1 653. 723 6 n0． 149 5-0. 150 8 nm,the system detection error from the original ±4% is reduced to ±0. 5% . Based on laser self-sta- bilizing technology,the distributed multi-point laser methane system can realize a real-time monitoring of methane in multiple channels,the measurement error is less than 1% . With the laser self-stabilizing technology,the system can re- alize the precise control of laser working wavelength,and then ensure the long-term stability of laser methane detection system’s performance during the environment temperature change and device aging.m,the working spectrum fluctuating range from 0. 138 1 - 0. 159 6 nm is reduced to

GUO Qinghua,YU Qing,GOU Yi. Research of distributed multi-point methane detection system which based on laser self-stabilizing tech- nology[J]. Journal of China Coal Society,2018,43(2):371-376.