基于谐波检测原理的双气室气体传感器研究

Research of a two gas cells sensor for gas detection based on harmonic wave principle

基于气体的近红外吸收机理,研究了一种双气室光纤气体传感系统。通过光纤光栅和压电陶瓷对宽带光源LED进行波长调制,获得与气体吸收峰对应的窄带反射出射光。利用谐波检测原理,检测测量气室和参考气室的二次谐波信号,以它们的比值作为系统输出,消除了吸收系数随环境的变化、光源光功率的波动和光路干扰对测量精度的影响。利用波分复用技术实现了多种气体的高精度测量,甲烷气体测量的实验结果表明该系统的测量灵敏度可以达到1×10-5。

Based on the near infrared Absorption of gases,an optical fiber gas sensor with two gas cells is described.The LED is used as a light source and the wavelength modulation is realized by modulating on fiber grating and piezoelectric ceramics (PZT) to Abstain narrowband reflection output light.Based on the principle of harmonic detection,the second harmonic signals from the measurement gas cell and the reference cell are measured.The ratio of the two second-harmonic signals is regarded as the output of system,which can be used for eliminating the interferences of the optical route to the high sensitivity detection,the change of Absorb modulus with the environment and the fluctuate of the laser′s power.Many kinds of gases are detected with high sensitivity by using wavelength division multiplexing(WDM) technology.The experiments of CH4 detection with the system has proved that the measurement sensitivity of the system is 1×10-5.