Non-invasive, opto-acoustic water current measurement system and method
AssigneeThe United States of America as represented by the Secretary of the Navy
InventorsJack Lloyd, Jeff Rish
Life of this patent
Estimating the term…
Abstract
A method and system are provided for measuring water current. An acoustically-modulated beam of radiation is transmitted to a target location on the surface of a body of water. As the beam transits the water, acoustic radiation propagates away from the beam towards the surface and experiences a Doppler shift in frequency relative to the acoustic frequency used for modulation. The Doppler shift is caused by current in the water through which the acoustic radiation transits. The Doppler-shifted frequency is measured as an indication of water current.
Claims19
A method of measuring water current, comprising the steps of:
- transmitting a beam of optical radiation to be incident at a target location on the surface of a body of water at an angle with respect to the surface, said beam being modulated by an acoustic frequency wherein, as said beam transits the water, energy from said beam is absorbed by the water thereby generating acoustic radiation in the water that propagates away from said beam as said beam transits the water such that a portion of said acoustic radiation propagates to the surface and experiences a Doppler shift in frequency relative to said acoustic frequency due to current in the water through which said portion transits wherein said portion exhibits a Doppler-shifted frequency;
- and
- measuring said Doppler-shifted frequency associated with said portion of said acoustic radiation as an indication of water current.
A method of measuring water current, comprising the steps of:
- transmitting a beam of optical radiation through the air to be incident at a target location on the surface of a body of water at an angle with respect to the surface, said beam having a wavelength in the range of 600-900 nanometers and being modulated by an acoustic frequency wherein, as said beam transits the water, energy from said beam is absorbed by the water thereby generating acoustic radiation in the water that propagates approximately perpendicularly away from said beam as said beam transits the water such that a portion of said acoustic radiation propagates to the surface and experiences a Doppler shift in frequency relative to said acoustic frequency due to current in the water through which said portion transits wherein said portion exhibits a Doppler-shifted frequency;
- and
- measuring said Doppler-shifted frequency associated with said portion of said acoustic radiation as an indication of water current.
A system for measuring water current, comprising:
- means for transmitting a beam of optical radiation to be incident at a target location on the surface of a body of water at an angle with respect to the surface, said beam being modulated by an acoustic frequency wherein, as said beam transits the water, energy from said beam is absorbed by the water thereby generating acoustic radiation in the water that propagates away from said beam as said beam transits the water such that a portion of said acoustic radiation propagates to the surface and experiences a Doppler shift in frequency relative to said acoustic frequency due to current in the water through which said portion transits wherein said portion exhibits a Doppler-shifted frequency;
- and
- means for measuring said Doppler-shifted frequency associated with said portion of said acoustic radiation as an indication of water current.
Dependencies are inferred from the claim text.