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Laser Remote Magnetometry Using Mesospheric Sodium
Author(s) -
Kane Thomas J.,
Hillman Paul D.,
Denman Craig A.,
Hart Michael,
Phillip Scott R.,
Purucker Michael E.,
Potashnik S. J.
Publication year - 2018
Publication title -
journal of geophysical research: space physics
Language(s) - English
Resource type - Journals
eISSN - 2169-9402
pISSN - 2169-9380
DOI - 10.1029/2018ja025178
Subject(s) - magnetometer , telescope , laser , optics , mesosphere , sensitivity (control systems) , magnetic field , physics , laser guide star , aperture (computer memory) , noise (video) , earth's magnetic field , remote sensing , materials science , environmental science , geology , atmospheric sciences , acoustics , quantum mechanics , electronic engineering , artificial intelligence , stratosphere , computer science , image (mathematics) , engineering
We have demonstrated a remote magnetometer based on sodium atoms in the Earth's mesosphere, at a 106‐km distance from our instrument. A 1.33‐watt laser illuminated the atoms, and the magnetic field was inferred from backscattered light collected by a telescope with a 1.55‐m‐diameter aperture. We theoretically predict a shot noise limited measurement sensitivity of 19 nT / Hz . The measured sensitivity was 162 nT / Hz due to a smaller returned intensity and smaller resonance strength than expected. The value of magnetic field inferred from our measurement is consistent with several models of the Earth's field shape to within a fraction of a percent. Projected improvements in optics, plus the use of advanced lasers or a large telescope, could result in 1 ‐ nT / Hz sensitivity.
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