提出一种基于双光纤光栅(FBG)差分光谱吸收技术的乙炔测量系统。以光纤光栅反射出的窄带光作为探测光, 基于红外吸收理论实现乙炔浓度的检测。通过引入参考光栅, 有效抑制了光路噪声、暗电流等干扰因素, 实现了大背景信号下微弱信号的测量;利用数字滤波技术, 消除了系统响应信号中的低频干扰, 提高了系统的稳定性和可靠性。实验结果证明系统具有良好的测试重复性和较高的测试灵敏度, 最低检测限约为25×10-6。本文的研究成果对进一步研究实现多组分混合气体的测试具有重要的意义。

A differential absorption system based double fiber Bragg gratings(FBG) system for sensing acetylene is proposed. In this system the reflected light from FBG is used as the probing light to detect acetylene. By the introduction of a reference FBG, the noise from the light path is reduced greatly, so that the weak responding signals buried in the strong background signal can be picked out. Furthermore, by using digital filter, undesirable low-frequency periodic interference in the collected signal is removed, which makes the system more reliable and stable. The experimental results show that the system has high sensing sensitivity in detecting acetylene and the lowest detection limit is 25×10-6. The proposed system has great potential for developing multi-gas sensing system in the future research work.