Omni-directional hydrophone
First Claim
1. A vibration-canceling omni-directional fiber-optic hydrophone comprising:
- a spheroid shaped detecting means for detecting acoustic energy, said spheroid shaped detecting means having increased sensitivity to acoustic energy signals and reduced sensitivity to vibrational noise;
said spheroid shaped detecting means further comprising a first means sensitive to both impinging acoustic energy and vibrational noise, a second means sensitive to vibrational noise only, said second means in close proximity to said first means, and a means for providing coherent light to said first means and said second means; and
a means for processing output signals from said spheroid shaped detecting means.
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Accused Products
Abstract
An omni-directional hydrophone having a pair of fiber-optic windings wrapped around a resilient ball to form a spherical acoustic sensor is provided. The fiber-optic pair has a first fiber which has a bonded jacket and a second fiber which has an unbonded jacket. The fiber with the bonded jacket is sensitive to both vibration of the mounting structure and impinging acoustic signals. The fiber with the unbonded jacket is sensitive to vibration but insulated from the acoustic signals. By comparing the signals from the two fibers, the hydrophone detects acoustic signals by detecting the phase difference between the two fibers. As both fibers are equally affected by vibration, there is no phase difference caused by vibration. This mechanization permits the canceling of vibration induced signals while retaining full sensitivity to acoustic signals. The hydrophone uses a standard fiber-optic laser source and detection system to convert the acoustic generated phase change to amplitude dependent voltage signals. The hydrophone is pressure and temperature insensitive.
49 Citations
19 Claims
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1. A vibration-canceling omni-directional fiber-optic hydrophone comprising:
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a spheroid shaped detecting means for detecting acoustic energy, said spheroid shaped detecting means having increased sensitivity to acoustic energy signals and reduced sensitivity to vibrational noise; said spheroid shaped detecting means further comprising a first means sensitive to both impinging acoustic energy and vibrational noise, a second means sensitive to vibrational noise only, said second means in close proximity to said first means, and a means for providing coherent light to said first means and said second means; and a means for processing output signals from said spheroid shaped detecting means. - View Dependent Claims (2, 3, 4, 5, 6, 7)
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8. A vibration-canceling omni-directional fiber-optic hydrophone comprising:
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means for providing coherent light; means for receiving coherent light, said receiving means having optical characteristics that vary when subjected to acoustic impingement; means for detecting vibration signals, said detecting means having optical characteristics that are insulated from acoustic impingement; said means for receiving coherent light and said means for detecting vibration signals configured to form an acoustically sensitive spheroid; means for processing output signals from said means for receiving coherent light and said means for detecting vibration signals; and means for demodulating processed output signals thereby obtaining a low vibration noise acoustic signal. - View Dependent Claims (9, 10, 11, 12, 13, 14, 15, 16, 17, 18)
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19. A vibration-canceling omni-directional fiber-optic hydrophone comprising:
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a sensing coil formed with an optical fiber encased within an acoustically sensitive jacket wherein said acoustically sensitive jacket is bonded to the optical fiber and wherein said optical fiber further comprises a light transmitting optical fiber core and a soft silicone buffer layer surrounding said optical fiber core between said optical fiber core and said bonded acoustically sensitive jacket; a reference coil formed with an optical fiber encased within a protective jacket wherein said protective jacket is not bonded to the optical fiber and wherein said optical fiber further comprises a light transmitting optical fiber core and a soft silicone buffer layer surrounding said optical fiber core between said optical fiber core and said unbonded protective jacket; an omni-directional acoustic sensing spheroid formed by winding said sensing coil and said reference coil in a collocated pairing around a compliant ball; an acoustically transparent material encapsulating said omni-directional acoustic sensing spheroid thereby forming a sealed, compliant spheroid; a coherent light source connected to and transmitting light to said reference optical fiber and said sensing optical fiber; and an electro-optic unit connected to and receiving transmitted light from said reference optical fiber and said sensing optical fiber suitable for determining phase shift differences between said sensing and reference optical fibers.
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Specification