High sensitivity, pressure compensated optical hydrophone

The use of optical hydrophones is gaining popularity in both fixed and towed arrays. The optical hydrophone enables the use of all optical interrogation systems and results in a very economical wet end to the array system. The most common design for optical hydrophones is an air-backed mandrel. When the hydrophone is required to work over large pressure ranges, the wall thickness of this mandrel becomes very thick to prevent buckling failure and reduces the sensitivity of the hydrophone proportionality. This reduced sensitivity places stringent requirements on the optical interrogation system. The optical hydrophone designs proposed in this SBIR overcome this sensitivity degradation with depth by developing several innovative pressure compensation schemes into the fiber optic hydrophone without unduly complicating the design or dramatically increasing the costs.