Design and Development of a fiber optic concentric composite mandrel hydrophone

A detailed survey of research work in the area of fiber sensors has been carried out. The paper aims at the optimized design and development of air-backed concentric composite mandrel hydrophone to be used in underwater sonar applications. Mandrel hydrophones with a foaming layer over the solid base layer showed very good improvement in the sensitivity. For the use of underwater applications structure stability is required and hence a composite concentric air backed mandrel with a central Aluminium thin walled tube as base layer and the foaming layer of plastic syntactic foam above the base layer of 5mm thickness has been designed and fabricated. Three types of sensors with various outer diameter keeping the foaming layer thickness the same have been fabricated, after undergoing both tensile and compressive load tests of the material. These three sensors were put in an acoustic water tank and carried out the sensitivity measurements using a Michelson interferometric test set up. Encouraging results were obtained and shown.