Magnetometers

Magnetometers are used to measure anomalies in the earth’s magnetic field. These can be due to local geologic features or man-made objects in the area (ie ship wrecks). Underwater magnetometers are typically towed behind a ship. Proton magnetometers operate on the principal that the protons in all atoms are spinning on an axis aligned with the magnetic field. Ordinarily, protons tend to line up with the earth's magnetic field. When subjected to an artificially-induced magnetic field, the protons will align themselves with the new field. When this new field is interrupted, the protons return to their original alignment with the earth's magnetic field. As they change their alignment, the spinning protons precess, or wobble, much as a spinning top does as it slows down. The frequency at which the protons precess is directly proportional to the strength of the earth's magnetic field.

Overhauser magnetometers use electron-proton coupling to produce stronger precession signals than conventional proton precession magnetometers. Optically pumped magnetometers (Cesium, Potasium, and Rubidium) make even more precise measurements of magnetic fields by determining the frequency of radio waves required to change the transparency of a glass vapor cell containing gaseous metal that is exposed (or pumped) to polarized light of very specific wavelength.

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