Reduced noise fiber optic towed array and method of using same
First Claim
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1. A fiber optic towed sensor array, comprising:
- a plurality of fiber optic sensor circuits arranged in parallel, each including a sensor and a separate optical fiber for conducting light to said sensor;
laser means for generating light to be injected into said respective optical fibers; and
processing means for processing outputs from the respective sensor circuits, wherein the contributions of particular sensors may be readily isolated by said processing means and crosstalk between sensors is virtually eliminated through the use of said separate optical fibers for each sensor;
wherein said sensor circuits are arranged such that the optical distance between adjacent sensors is on the order of 5 to 10 meters, and said laser source comprises a pulsed laser having a pulsed length of less than 50 nanoseconds.
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Abstract
A sensitive towed optical fiber sensor array 50, wherein the fiber sensors (60A-60N) are connected in parallel, and the optical fiber cable (34) is paid out from the towing ship at a velocity about equal to but opposite to the velocity of the towing ship. The fiber sensors (60A-60N) are immune to electromagnetic interference, and the output of the sensors can be isolated readily to the parallel hookup of the sensors. Turbulence and acceleration noise is greatly reduced due to the manner in which the fiber cable (34) is paid out, and crosstalk between sensors is eliminated.
251 Citations
8 Claims
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1. A fiber optic towed sensor array, comprising:
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a plurality of fiber optic sensor circuits arranged in parallel, each including a sensor and a separate optical fiber for conducting light to said sensor; laser means for generating light to be injected into said respective optical fibers; and processing means for processing outputs from the respective sensor circuits, wherein the contributions of particular sensors may be readily isolated by said processing means and crosstalk between sensors is virtually eliminated through the use of said separate optical fibers for each sensor; wherein said sensor circuits are arranged such that the optical distance between adjacent sensors is on the order of 5 to 10 meters, and said laser source comprises a pulsed laser having a pulsed length of less than 50 nanoseconds. - View Dependent Claims (2, 3, 4)
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5. A method for reducing turbulence and acceleration noise in a towed sensor cable array towed behind a towing vessel moving at a vessel velocity, comprising paying out said cable array from said vessel at a velocity about equal and opposite to said vessel velocity;
wherein said cable array has a nominal diameter of one centimeter, and the cable array is paid out from said vehicle at a rate so that the velocity of the cable array through water is no greater than 15 centimeters per second. - View Dependent Claims (6, 7, 8)
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8. The method of claim 5 wherein said sensor cable array comprises a fiber optic sensor array.
Specification