Open AccessAdvances in magneto‐optical imaging applied to rock magnetism and paleomagnetism
Author(s) -
Uehara Minoru,
van der Beek Cornelis Jacominus,
Gattacceca Jérôme,
Skidanov Vladimir A.,
Quesnel Yoann
Publication year - 2010
Publication title -
geochemistry, geophysics, geosystems
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.928
H-Index - 136
ISSN - 1525-2027
DOI - 10.1029/2009gc002653
Subject(s) - remanence , demagnetizing field , geology , magnetism , magnetic field , faraday effect , magnetization , optics , condensed matter physics , physics , quantum mechanics
We present results of the magneto‐optical imaging technique applied to rock samples. This technique measures the magnetic flux threading a magneto‐optically active film, which rotates the polarization direction of transmitted light (Faraday rotation) and is directly placed on the sample. Through the analyzer of a reflected light microscope, the vertical component of the surface magnetic field of the sample is observed and can be quantified through a specific calibration procedure. Owing to the thin magneto‐optically active film (5 μ m) and the small sample‐to‐film distance (∼1 μ m), stray fields produced by magnetic grains in rocks carrying saturation isothermal remanent magnetization are successfully imaged with a spatial resolution of 10 μ m. We can also image the surface field distribution of rocks carrying natural remanent magnetizations by modulating the analyzer angle. In addition to its high spatial resolution, this technique offers a direct comparison between magnetic and reflected light images. Therefore, this new technique appears to be a powerful tool to map and identify the carriers of magnetic remanence in rock samples.