Optics: measuring and testing – For optical fiber or waveguide inspection
Patent
1989-11-30
1991-01-22
Evans, F. L.
Optics: measuring and testing
For optical fiber or waveguide inspection
356301, G01N 2100, G01J 344
Patent
active
049866567
ABSTRACT:
A method of remotely measuring the diffuse attenuation coefficient K of ocean water from an airborne platform such as an aircraft. By directing a pulsed laser beam having a wavelength .lambda..sub.0 from the platform into the water, the beam interacts therewith to produce inelastic Brillouin backscatter signals at the wavelength .lambda..sub.1, where .lambda..sub.1 .noteq..lambda..sub.0. The desired backscatter propagate generally oppositely to the direction of propagation of the pulsed laser beam so that the backscatter can be received and collected at the platform. The upwelling optical energy includes the desired backscatter signals, which are separated out from the remainder of the upwelling optical energy. The separated backscatter signals are converted to equivalent electrical signals and periodically analyzed to generate therefrom the diffuse attenuation coefficient of the ocean water at the .lambda..sub.1 wavelength at periodic depths beneath the water surface. In another aspect of this invention both the Brillouin backscatter signals and the Raman backscatteer signals are separately filtered out to simultaneously measure the diffuse attenuation coefficient of the water at two distinct wavelengths. In another aspect of this invention the diffused attenation coefficient K is measured from a submerged platform, such as a submarine. This has the advantage of allowing deep ocean layers to be measured along with ocean water beneath the polar ice cap.
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Leonard Donald A.
Sweeney Harold E.
Titterton Paul J.
Evans F. L.
Gilbert Douglas M.
GTE Government Systems Corporation
Hantis K. P.
Lawler John F.
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