Method of remotely detecting submarines using a laser
First Claim
1. An underwater method of detecting the wake of a first submerged submarine from a second submerged submarine comprising the steps of:
- generating from within said second submarine a pulsed laser beam;
directing said beam upwardly from said second submarine with an intensity sufficient to penetrate the thermocline of said water;
detecting in said second submarine the Rayleigh and Brillouin backscatter light components produced by the interaction of said beam with said water;
mixing said Rayleigh and Brillouin light components and thereby producing a heterodyne signal having a frequency fB ;
periodically converting the heterodyne signal into a temperature/depth profile; and
translating said temperature/depth profile into spatial patterns for comparison with patterns characteristic of the wake of a moving submarine.
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Accused Products
Abstract
Subsurface waves in an ocean are created by the turbulence in a submarine'"'"'s wake. These waves can be remotely detected by a search submarine by monitoring subsurface water temperatures using a laser. A pulsed laser beam is directed into the water to at least the depth of the thermocline and an analysis is made of the resultant Brillouin and Rayleigh backscatter components. Wavelength shifted Brillouin scatter is mixed with the unshifted Rayleigh scatter in a self-heterodyne manner for each volume element of illuminated water, and the frequency of the heterodyne signal is measured and converted into equivalent temperature values. This produces the desired temperature-depth profile of the water enabling detection of the first submarine by tracking the internal waves at or near the ocean thermocline.
19 Citations
23 Claims
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1. An underwater method of detecting the wake of a first submerged submarine from a second submerged submarine comprising the steps of:
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generating from within said second submarine a pulsed laser beam; directing said beam upwardly from said second submarine with an intensity sufficient to penetrate the thermocline of said water; detecting in said second submarine the Rayleigh and Brillouin backscatter light components produced by the interaction of said beam with said water; mixing said Rayleigh and Brillouin light components and thereby producing a heterodyne signal having a frequency fB ; periodically converting the heterodyne signal into a temperature/depth profile; and translating said temperature/depth profile into spatial patterns for comparison with patterns characteristic of the wake of a moving submarine. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8)
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9. An underwater method of detecting the wake of a first submerged submarine from a second submerged submarine comprising the steps of:
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generating from within said second submarine a pulsed laser beam; directing said beam downwardly from said second submarine with an intensity sufficient to penetrate the thermocline of said water; detecting in said second submarine the Rayleigh and Brillouin backscatter light components produced by the interaction of said beam with said water; mixing said Rayleigh and Brillouin light components and thereby producing a heterodyne signal having a frequency fB ; periodically converting the heterodyne signal into a temperature/ depth profile; and translating said temperature/depth profile into spatial patterns for comparison with patterns characteristic of the wake of a moving submarine. - View Dependent Claims (10, 11, 12, 13, 14, 15, 16)
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17. An underwater search method for detecting a first submerged submarine from a second submerged submarine, said search method comprising the steps of:
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generating from within said second submarine a pulsed laser beam having an intensity sufficient to penetrate the thermocline of said water; directing said beam from said second submarine into said water in a direction toward said thermocline; detecting in said second submarine the Rayleigh and Brillouin backscatter light components produced by the interaction of said beam with said water; mixing said Rayleigh and Brillouin light components and thereby producing a heterodyne signal having a frequency fB ; periodically converting the heterodyne signal into a temperature/depth profile; translating said temperature/depth profile into spatial patterns periodically repeating the above steps by traversing said beam in a plane othogonal to the direction of travel of said second submarine thereby creating a library of spatial profiles; comparing said library of spatial profiles with spatial patterns characteristic of the wake of a moving submarine; and
,tracing said wake to determine the location of the first submarine. - View Dependent Claims (18, 19, 20, 21, 22, 23)
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Specification