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Graduate Student Seminar - 03/13/2015

"Remote Optical Magnetometry (Proposing and Analyzing Two Methods)"

by Zachary Epstein

Friday, March 13, 2015 -- 12:00 p.m.
Large Conference Room, 1207 Energy Research Facility

Advisor:  Professor Phillip Sprangle

A method for remote optical measurements of magnetic field variations above the surface of seawater is proposed and analyzed.  This magnetometry mechanism is based on the fact that polarized laser light in the presence of Earth’s magnetic field, when reflected off the water surface or off an underwater object, will undergo a polarization-rotation.  The two mechanisms responsible for a polarization change are the Surface Magneto-Optical Kerr Effect (SMOKE) and the Faraday rotation effect.  For both mechanisms, the magnitude of the reflected, polarization-rotated field is proportional to Earth’s local magnetic field. The polarization rotation due to SMOKE is shown to be small while the contribution due to Faraday rotation can be significant.  An analytical expression is obtained for the polarization-rotated field when the incident plane wave is at an arbitrary angle and polarization with respect to the water’s surface.  Effects due to the presence of aqueous ions, the water’s uneven surface, and the conducting object’s orientation are discussed. A second mechanism based on hyperpolarized xenon 129 nuclear spin will also be discussed.

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