System for measuring differential pressure in an underwater environment

A system for measuring differential pressure in an underwater environment, comprising:

• at least one first transceiver unit comprising a light source, detection means and signal processing means;
• at least one first fiber measurement instrument configured to be positioned in a first position in said underwater environment and comprising:
• a first rigid compartment in sealed fluid connection with a first rigid tube, the first compartment being filled with a first liquid;
• a second at least partially rigid compartment in sealed fluid connection with a second at least partially flexible tube, the second compartment being filled with a second liquid;
• a third tube for underwater pressure tapping, said third tube opening into the underwater environment and being in fluid connection with the second tube;
• at least one first valve configured to allow, in the open position, a fluid connection between the first tube and the second tube, in order to maintain the first compartment and the second compartment at equal pressure, and configured to sealably separate, in the closed position, the first tube from the second tube;
• a membrane configured to separate the first compartment and the second compartment;
• a third sealed compartment filled with a fluid at atmospheric pressure;
• at least one first window, transparent within a given wavelength range, arranged in a shared wall between said third compartment and one of the first or second compartments;
• at least one first fiber optic head configured to form a first fiber interferometric sensor with said first transceiver unit, wherein said first fiber interferometric sensor is configured to measure, in the closed position of the first valve, through said first window, at least a first displacement of the membrane resulting from a pressure variation between the first compartment and the second compartment when the first measurement instrument experiences a variation in underwater pressure.