A novel all-fiber vibration velocity measurement system with high contrast of interfering fringes is proposed and
demonstrated. The configuration utilizes polarization beam splitters to remove the unwanted reflected light beams. With
a shaker vibration measurement experiment, it is shown that the system can successfully improve the interfering fringe
contrast to 69.8% significantly and the results can be better if there is no counter reflecting light in 3×3 coupler. The
system is also convenient in free-surface velocity measurement application of the shock wave and the experiment
achieves long time measurement (700μs) in strong disturbance.