Deep Fiber Optic Vector Sensor Array

Vibration Impact and Pressure Sensors proposes to develop a compact Fiber Optic Vector Sensor Array to be deployed in an expendable sonobuoy and operated close to the ocean bottom (below critical depth). It consist of multiple vector sensors (hydrophone, single axis, biaxial or triaxial accelerometer) and compasses. A pair of single mode optic fibers interconnects the passive vector sensor array located 6 km below sea level to the Electronic Readout board within the sonobuoy’ s Lower/Upper Electronic Module. The hydrophone provides sound amplitude, while the accelerometers provide the direction of sound wave, the compasses provide heading information, which is important considering the potential twisting of the interconnecting optical cable. A light source from the electronic module excites the Fiber Optic Vector Sensors. Each of the optical sensors, built to work at unique ranges of the optical spectrum, modulates the light within its corresponding wavelength range in proportion to the measurand; therefore the light returning from the FOVS contains the information of all the sensors at different preset wavelength slots in a wave division multiplexing fashion. The optical sensors are micromachined MOMS silicon chips which consume no electrical power. The power consumption of the electronic module is mainly for the light