Low flow-noise conformal fiber optic hydrophone
First Claim
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1. A vibration-canceling fiber optic hydrophone comprising:
- a. a sensing coil formed with an optical fiber having a jacket which is acoustically sensitive bonded to the optical fiber;
b. a reference coil formed with an optical fiber having a protective jacket that is not bonded to the optical fiber;
c. a planar acoustic sensing disk formed by forming said sensing coil and reference coil into a planar concentric spiral;
d. an acoustically transparent material encapsulating said planar acoustic sensing disk thereby forming a sealed, compliant planar layer;
e. a coherent light source connected to and transmitting light to said reference optical fiber and to said sensing optical fiber; and
f. an opto-electronic unit connected to and receiving transmitted light from said reference and sensing optical fibers suitable for determining phase shift differences between said sensing and reference optical fibers.
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Abstract
A fiber-optic hydrophone having a pair of jacketed fiber optic windings fed in a concentric planar spiral configuration in a layer of polyurethane is provided. One of the fiber optic windings has a fiber with a bonded acoustically sensitive jacket thereby increasing its sensitivity to acoustic energy. The second fiber optic winding, the reference winding, has a unbonded jacket enclosing the fiber resulting in reduced sensitivity to acoustic energy. Sensitivity to vibrational energy; however, is not reduced. The combining of signals from the pair of fibers provides a vibration-canceled acoustic signal.
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Citations
12 Claims
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1. A vibration-canceling fiber optic hydrophone comprising:
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a. a sensing coil formed with an optical fiber having a jacket which is acoustically sensitive bonded to the optical fiber; b. a reference coil formed with an optical fiber having a protective jacket that is not bonded to the optical fiber; c. a planar acoustic sensing disk formed by forming said sensing coil and reference coil into a planar concentric spiral; d. an acoustically transparent material encapsulating said planar acoustic sensing disk thereby forming a sealed, compliant planar layer; e. a coherent light source connected to and transmitting light to said reference optical fiber and to said sensing optical fiber; and f. an opto-electronic unit connected to and receiving transmitted light from said reference and sensing optical fibers suitable for determining phase shift differences between said sensing and reference optical fibers.
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2. A vibration-canceling fiber optic hydrophone comprising:
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a. means for providing coherent light; b. means for receiving coherent light, said receiving means having optical characteristics which vary when subjected to acoustic impingement; c. means for detecting vibration signals, said detecting means being insulated from acoustic impingement; d. means for processing output signals from said receiving means and said detecting means; and e. means for demodulating processed output signals to obtain a low vibration noise acoustic signal. - View Dependent Claims (3, 4, 5, 6, 7, 8, 9, 10, 11, 12)
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Specification