High sensitivity measurement of seawater velocity based on panda fiber coupled aluminum-cantilever

A target-type fiber optic velocity sensor is presented based on panda fiber attached to aluminum-cantilever, and experimentally demonstrated high sensitivity and precision measurement of seawater velocity. In this paper, the velocity sensitivity formula of the sensor is derived first, and the effective elastic coefficient (Pe) of Panda fiber is calculated to be 0.988 by finite element algorithm. Secondly, seawater velocity measurement system was established experimentally with circulating flow tank, and experimental results showed that the velocity sensitivity is up to 114.69 nm/(ms^‐1) at 0.31 m/s when the target radius and cantilever thickness are 2.00 cm and 0.20 mm respectively, which proves that highly sensitive velocity measurement is achieved with panda fiber coupled aluminum-cantilever. Comparing the measurement results of the sensor with Acoustic Doppler Velocimetry, the average absolute error and the root mean square error (RMSE) are 0.012 m/s and 0.00249 m/s respectively, which realized high precision measurement of seawater velocity. Therefore, the system has good application in the measurement of seawater velocity due to its advantages of high sensitivity, wide range and simple structure.