The invention relates to a method of interrogating an interferometric optical fibre sensor system. The system comprises a laser source for generating interrogation light and an sensor array with at least a first and a second reflector and with a sensor delay being a difference in propagation time for light being reflected from the first and second reflector, respectively. The method comprises continuously and repeatedly frequency sweeping the interrogation light from the laser source within a sweep bandwidth, SBW, over a sweep duration, tsw, with a substantially constant sweep rate r = SBW / tsw, to produce a swept interrogation light signal. The swept interrogation light signal is launched into the sensor array. The method further comprising detecting reflected signals being returned from the sensor array by each of the reflectors, respectively, wherein detection comprises mixing a return light signal from the array with a local oscillator, LO, signal onto an optical receiver to produce an electrical radio frequency signal. The electrical radio frequency signal is then demultiplexed into a first and second signal channel, corresponding to the first and second reflector, respectively. Each of the first and second signal channel are demodulated into a first phase response from the first reflector and a second phase response from the second reflector. Finally, the method comprises subtracting the first phase response from the second phase response to obtain a sensor phase signal. The invention further relates to an interferometric optical fibre sensor system.
G01D 5/26 - Moyens mécaniques pour le transfert de la grandeur de sortie d'un organe sensible; Moyens pour convertir la grandeur de sortie d'un organe sensible en une autre variable, lorsque la forme ou la nature de l'organe sensible n'imposent pas un moyen de conversion déterminé; Transducteurs non spécialement adaptés à une variable particulière utilisant des moyens optiques, c. à d. utilisant de la lumière infrarouge, visible ou ultraviolette
The invention relates to a hydrophone housing. The housing comprises an outer casing with an exterior shape being in close contact with sediment when buried therein and having a deflectable wall part. Solid material partly fills the casing to define an outer chamber behind the deflectable wall part, a cavity shaped so that an inner chamber is defined immediately surrounding a hydrophone sensing element held therein, and a first duct for liquid flow communication between the outer chamber and the cavity or an internal volume of the hydrophone sensing element. Thereby, a hydraulic coupling is provided so that an acoustic pressure causing small radial displacements of outer surface of the housing will, via liquid in the first duct, cause large radial displacements of the hydrophone sensitive element. The area of the deflectable wall part is much larger than the area of the sensitive element so that only small displacements of the housing are required to cause large displacements at the hydrophone sensing element.
G01H 9/00 - Mesure des vibrations mécaniques ou des ondes ultrasonores, sonores ou infrasonores en utilisant des moyens sensibles aux radiations, p.ex. des moyens optiques
A rotary joint or swivel device for ensuring a continuous connection between two items that rotates with respect to each other, for example between an instrumentation unit on a fixed installation and sensor elements in a cable on a rotating cable reel or drum, is provided. The rotary joint or swivel device comprises a minimum of two spools 1A,B to coil a connecting cable 3. A first spool 1A is coupled to a first, static, item 40. A second spool 1B is coupled to a second, rotatable, item 30. A guiding arm 4 feeds the connecting cable 3 from the first 1A to the second 1B spool. Correspondingly, a method for ensuring a continuous connection between two items 30,40 that rotates with respect to each other is provided. The method comprises arranging a rotary joint or swivel device according to any of the embodiments of the invention between the two items.
H02G 1/10 - Méthodes ou appareils spécialement adaptés à l'installation, entretien, réparation, ou démontage des câbles ou lignes électriques pour poser les câbles, p.ex. appareils de pose sur véhicule dans ou sur l'eau
H02G 11/00 - Installations de câbles ou de lignes électriques entre deux pièces en mouvement relatif
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