Fiber-optic hydrophone

A fiber-optic hydrophone comprising:

• a compliant sensing mandrel;
• a first optical fiber wound around the compliant sensing mandrel;
• a rigid reference mandrel surrounding the compliant sensing mandrel, the reference mandrel being spaced from the sensing mandrel so as to provide a sealed cavity therebetween;
• a second optical fiber wound around the rigid reference mandrel, the first and second optical fibers comprising different arms of an interferometer;
• for each mandrel, at least one flexible sealing member sealing the mandrel to the hydrophone;
• a support member disposed inside the sensing mandrel, the support member being spaced from the sensing mandrel so as to provide a channel therebetween for providing fluid communication therein with the sensing mandrel;
• and
• means for providing fluid flow into the channel.

A fiber-optic hydrophone comprising:

• a compliant sensing mandrel;
• a first optical fiber wound around the compliant sensing mandrel;
• a rigid reference mandrel positioned adjacent the compliant sensing mandrel;
• a second optical fiber wound around the rigid reference mandrel, the first and second optical fibers comprising different arms of an interferometer;
• a housing enclosing the sensing and reference mandrels and the first and second optical fibers wound thereon, the housing being spaced from the sensing mandrel and first optical fiber so as to provide a sealed cavity therebetween;
• at least one flexible sealing member sealing the housing to at least one of the sensing mandrel and the reference mandrel;
• a support member disposed inside the sensing mandrel, the support member being spaced from the sensing mandrel so as to provide a channel therebetween for providing fluid communication therein with the sensing mandrel;
• and
• means for providing fluid flow into the channel.

A fiber-optic hydrophone comprising:

• a compliant sensing mandrel;
• a first optical fiber wound around the compliant sensing mandrel;
• a rigid reference mandrel positioned inside the sensing mandrel, at least a portion of the reference mandrel being spaced from the sensing mandrel so as to provide a channel therebetween for providing fluid communication therein with the sensing mandrel;
• a second optical fiber wound around the rigid reference mandrel, the first and second optical fibers comprising different arms of an interferometer;
• at least one flexible sealing member sealing the sensing mandrel to the hydrophone;
• and
• a tube in fluid communication with the channel for permitting pressure equalization between the exterior of the hydrophone and the channel.

A fiber-optic hydrophone, comprising:

• a compliant sensing mandrel;
• a first optical fiber wound around the compliant sensing mandrel;
• a rigid reference mandrel positioned inside the sensing mandrel, at least a portion of the reference mandrel being spaced from the sensing mandrel so as to provide a sealed cavity between the sensing mandrel and the reference mandrel;
• a second optical fiber wound around the rigid reference mandrel, the first and second optical fibers comprising different arms of an interferometer;
• and
• a pair of O-rings sealing the sensing mandrel to the reference mandrel.