The optimal design of a 3D column type fiber-optic vector hydrophone

Abstract

A 3-dimentional fiber-optic vector hydrophone, with many advantages including high sensitivity, large dynamic range, intrinsic immunity to electromagnetic interference and light weight, is becoming a hotspot of new-style vector sensors. For array applications, this review has discussed the finite element methods and experimental results of the hydrophone. A fiber-optic flexural disk vector hydrophone has been developed and related metrology aspects of measurement have been demonstrated. To figure out the issue of fiber-optic vector hydrophone, we optimize the hydrophone with an optical scheme, mechanism construction and sensing properties. In the optical scheme aspect, we replace the traditional optical devices with low reflectivity a fiber Bragg grating to simplify the optical scheme and minimize the sensor size. In the sensing properties aspect, we optimize the sensing parameter of the fiber-optic acceleration component with finite element analysis. The influence factor of the acoustic performance is discussed. In the mechanism construction aspect, a 3-dimetional isolated acceleration sensing structure is presented with a fiber-optic pressure component outside. A column type fiber optic vector hydrophone sample is then introduced. The size of the hydrophone is ϕ60mm×125mm. The acceleration sensitivity of the acceleration component is 22.5dB ref.1rad/g; and, with fluctuation of ±1.5dB ref.1rad/g at the range from 100Hz to 1000Hz. The equivalent pressure phase sensitivity in water of each axis is −183.5dB ref. 1rad/uPa@100Hz ∼ −159dB ref. 1rad/uPa@1000Hz; and, with fluctuation of ±1.5dB at the range from 100 to 1000Hz. The cross talk of each axis is below −20dB. The pressure sensitivity of the pressure component is −131.8 ref. 1rad/uPa; and, with fluctuation of ±1dB. We also test the directionality of the 3 acceleration component and pressure component. It has a good directionality performance and the maximum value non uniformity of the acceleration component is below 1dB.