基于双金属膜片结构的海底地震勘探光纤加速度传感器研究

Research on a fiber optic accelerometer based on double-metal diaphragm for seabed seismic detection application

针对全光海底地震检波器技术的特殊应用需求,设计了一种基于双金属矩形膜片的缠绕式光纤加速度传感器。利用弹性力学理论对光纤加速度传感器的加速度灵敏度和一阶共振频率的特性进行了分析,制作了光纤加速度传感器样品并对其性能进行了测试。结果表明,本文加速度传感器的灵敏度为45dB re∶0dB=1rad/g,一阶共振频率在820Hz左右,与理论分析值很好吻合。在10～400Hz工作带宽中,交叉去敏度约为30dB。测试系统中,使用的相位生成载波(PGC)解调算法的最小相位检测精度为10-5 rad/Hz1/2,因此理论能探测的最小加速度信号为56ng/Hz1/2。由于采用全金属结构,本文类型光纤加速度传感器能够更好地满足海底永久布放检波器的特殊要求。

n this paper,we present a double-metal rectangular diaphragm based fiber optic accelerometer for seabed seismic detection application. We analyze sensitivity and resonance frequency of this sensor by way of mechanics of elasticity. The results show that the accelerometer can achieve an axis sensitivity of 45 dB re ： 0 dB=l rad/g,a cross sensitivity of about 30 dB between 10 Hz and 400 Hz,and the reso-nance frequency of aboUt 820 Hz, which agree well with the theoretical analysis. In this system, the minimum measurable demodulation phase of the phase-generated carrier （PGC） is 10-s rad/Hz^1/2 , and the minimum acceleration reaches 56 ng/Hz^1/B theoretically. With an all-metal structure, this type of accelerometer can better adapt to the special requirements of Permanent deed seabed ~eophone.