高精度连续型光纤F-P腔液位传感器

High precision and continuous optical fiber F-P cavity liquid level sensor

提出一种基于光纤法布里-珀罗(Fabry-Perot,F-P)腔干涉仪原理的高精度连续型光纤液位传感器,它根据不同的液体高度产生不同的压强的原理实现液位测量。传感器通过MEMS技术和微光结构加工工艺研制,确保了传感器各项设计要求;系统采用双通道补偿光路以及双路输出比值为信号的处理方式,有效降低了环境因素的影响;利用低双折射单模光纤结合消偏技术,大幅减少了光路中“寄生干涉”和“偏振诱导信号衰落”对光纤F-P传感器测量精度的影响。实验表明,该传感器的灵敏度为0.8mV/mm,测量精度为<±2mm,分辨力为<±1mm,系列样品中最大量程可达30m,而且结构简单,安装方便。

A high precision continuous liquid level sensor based on optical fiber Fabry-Perot cavity interferometer is introduced in the paper, which detects liquid level based on the principle of ＂pressure of liquid depending on its level＂. The sensor is exactly fabricated by MEMS and micro-optics structure technologies, which can ensure its design demands. The sensor system works with double-channel compensation optical path and executes signal processing for the ratio of the double channel output, thus effectively reducing the influence of environment. By using birefraction single mode fiber in combination with depolarization technique, the influence to the measurement accuracy caused by ＂spurious interference in the optical route＂ and ＂polarization-induced fading （PIF）＂ in the optic fiber link has been greatly reduced. Experiment results show that the sensor is characteristic of simple structure and convenient installation, with sensitivity （0.8mV/mm）, accuracy （〈±2mm） , resolution （〈±1mm） . The largest testing range can reach 30m.