ASA 125th Meeting Ottawa 1993 May

2aEA7. A planar eight-elemental flexural disk fiber optic acoustic sensor.

D. A. Brown

G. B. Netzorg

B. White

D. Kapolka

David L. Gardner

Steven L. Garrett

Phys. Dept., Naval Postgraduate School, Monterey, CA 93943

Interferometric fiber optic flexural disk hydrophones made of aluminum, castable epoxy, and composite materials have previously been constructed and reported [D. Kapolka et al., J. Acoust. Soc. Am. 91, 2325(A) (1992)]. These hydrophones consist of a closed cylinder with fiber coils bonded to the sides of the two end caps in a push--pull fashion in order to increase acoustic sensitivity and allow for cancelation of acceleration induced signals. It is possible to sum in series the phase modulations induced in multiple transducers (e.g., flexural disks) using the two legs of the interferometer. This will enhance the spatial averaging capability of the sensor due to its increased size. The sensor self-noise arising from flow-induced pressure fluctuations can then be reduced resulting in improved detectability. The fabrication and performance of a sensor comprising 8 flexural disks and 16 coils of optical fiber will be discussed. [Work supported by the Naval Sea Systems Command.] [sup a)]LT., USN.