Patent ID: 8676008

Claim:
A Bragg grating fibre hydrophone comprising: a fluid cavity ( 1 ); and an optical fibre ( 2 ) in which a Bragg grating ( 3 ) is integrated, wherein said optical fibre ( 2 ) extends through said fluid cavity ( 1 ) along a longitudinal axis (X) and in such a manner that said Bragg grating ( 3 ) is positioned inside the fluid cavity, said fluid cavity ( 1 ) is filled with a compressible fluid and is delimited by a casing ( 4 ) comprising two ends ( 5 a , 5 b ) integral with the optical fibre ( 2 ), said casing ( 4 ) comprises at least one part formed by an extensible and compressible tube ( 6 a , 6 b ) extending along the longitudinal axis (X), wherein said part formed by the extensible and compressible tube ( 6 a , 6 b ) comprises an outer end coinciding with one of the two casing ends ( 5 a , 5 b ), and is configured to be longitudinally deformed by a difference in the pressures applied to its walls, causing a length variation of the optical fibre ( 2 ) measured by a variation of wavelength of a luminous flux extracted from the optical fibre ( 2 ), and said casing ( 4 ) comprising two parts formed by the extensible and compressible tube ( 6 a , 6 b ), and a rigid intermediate part ( 7 ) separating said parts formed by the extensible and compressible tube ( 6 a , 6 b ), wherein each of the outer ends of the parts formed by the extensible and compressible tube ( 6 a , 6 b ) coincide with one of the two ends ( 5 a , 5 b ) of the casing ( 4 ), respectively.