全光纤可测量任意反射面的速度干涉仪,对强动载下的界面运动速度测量具有重要意义。基于传统光纤速度干涉仪的特点,设计了一种新型全光纤速度测量系统。该系统不仅能消除延迟线圈的分布式相位调制噪声,还能得到高条纹对比度的干涉信号。采用偏振分束器替代耦合器,应用琼斯矩阵法分析推导了偏振分束器能够消除系统中的非相干光束原理。振动台表面速度测量的实验结果表明,该系统能得到89.1%条纹对比度的干涉信号,大幅提高系统信号噪声比,并且相比Levin结构的传统干涉仪能抑制延迟光纤线圈的相位噪声超过30dB。
All-fiber velocity interferometer system for measuring any reflector plays a significant role in surface veloc- ity measurement of moving target under strong pressure. Based on the characteristic of traditional fiber velocity inter- ferometer, a novel all-fiber vibration velocity measurement system is proposed and designed. The system can not only remove the distributed phase modulation noise of the delay coil essentially, but also obtain the interfering signals with high fringe contrast. The system configuration utilizes polarization beam splitters to replace couplers, and adopts Jones matrix method to analyze and deduce the principle that using polarization beam splitters can remove the non-interfer- ing light beams in the system. The experiment results of surface vibration speed measurement show that the system can successfully obtain the interfering fringe signals with fringe contrast of 89.1% , and improve the signal-to-noise ratio significantly. The proposed system can suppress the delay-coil-induced phase noise by more than 30dB com- pared with the traditional interferometer with Levin's structure.