Fiber Optic Gradient Hydrophone Construction and Calibration for Sea Trial.
NAVAL POSTGRADUATE SCHOOL MONTEREY CA
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A Mach-Zehnder interferometric fiber optic gradient hydrophone, for operation at 632.8 nm wavelength, was designed and constructed for testing in the laboratory. Two individual fiber optic hydrophone sensing coils with 10 m of fiber each were wound and potted on an epoxy mandrel and their respective sensitivities were obtained. They then were mounted on a rigid bar, separated by 10 cm, to form a gradient hydrophone. The sensitivity of this arrangement then was obtained in a calibrator which allowed the coil pair to be rotated 360 deg. Since the laboratory interferometric system was too large to be used in the sea trial tests, a second interferometric system, operating at 830 nm wavelength, using diode lasers was designed and constructed. This was mounted in an experimental apparatus designed and constructed for sea trial. A sea trial of a standard Navy type DIFAR hydrophone was conducted to test the effectivenesss of the experimental apparatus. The results of the laboratory tests are summarized and discussed and recommendations for further studies are presented. Keywords Fiber optic sensor Hydrophone Acoustic hydrophone Mach-Zehnder interferometer Pressure gradient hydrophone Interferometric sensor Directional dipole hydrophone.
- Acoustic Detection and Detectors
- Fiber Optics and Integrated Optics