Hydrophone Based on Fiber Bragg Gratings

• Main Authors: KUO, CHAN-YU, 郭展宇
• Other Authors: LIU, WEN-FUNG
• Format: Others
• Language: zh-TW
• Published: 2018
• Online Access: http://ndltd.ncl.edu.tw/handle/8tc2e2

碩士 === 逢甲大學 === 電機工程學系 === 106 === This thesis proposed a shape-curved hydrophone based on fiber Bragg gratings to detect acoustic waves in water. In comparison with the previous design, the shape-curved design can sense a larger angle and then receive more directions of signals. The sensing principle is based on the acoustic wave to push and to vibrate the thin film and then to stretch the fiber Bragg gratings. The sensing grating wavelength will be shifted forth and back to create different overlaps with the matching grating wavelength to cause the reflected light intensity variation. Then, the detected light signal is converted into a voltage-frequency electrical signal and displayed on oscilloscope for further analysis. In addition, fiber etching technology is used to reduce the fiber diameter for increasing the sensor sensitivity. Moreover, we also investigate the effect of different directions of acoustic source and curvatures of polymer structure on the frequency response. By means of the frequency response curves, the shaped-curved hydrophone has stable efficiency with the ability of sensing angle of 60°. The shape-curved hydrophone can accurately detect the acoustic wave under the water by a simple design. Because of fiber hydrophone has excellent characteristics like light weight and easier to maintained than conventional electrical types, it belongs to be a novel research.