Research of distributed multi-point methane detection system based on laser self-stabilizing technology

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