Patent ID: 8687927

Claim:
A Bragg grating fiber hydrophone, the Bragg grating fiber hydrophone comprising: a fluid cavity; and an optical fiber in which a Bragg grating is integrated, the optical fiber extending through the fluid cavity such that the Bragg grating is positioned inside the fluid cavity, wherein the fluid cavity is filled with a compressible fluid and is delimited by a rigid casing extending along a longitudinal axis, the rigid casing comprising two end faces each comprising an opening closed by a deformable diaphragm fastened to the optical fiber, the rigid casing having a length such that a length of the hydrophone is shorter than acoustic wavelengths that are measured, the optical fiber extends through the fluid cavity along the longitudinal axis of the rigid casing, the optical fiber being longitudinally a pre-stressed optical fiber, tension of the optical fiber being held by a holding means that is leaning on each of the end faces of the rigid casing, respectively, the deformable diaphragm is configured to be deformed by a difference in pressures applied to faces of each of the deformable diaphragms, causing a length variation of the optical fiber measured by a variation of wavelength of a luminous flux extracted from the optical fiber, and the hydrophone is usable within an acoustic frequency range between 0.4 Hz and 10 kHz.