Domain observation technique for Nd-Fe-B magnet in high magnetic field by image processing using liquid crystal modulator

摘要

A different domain observation technique by modulation of a polarizing plane has been developed for Nd-Fe-B sintered magnets. A liquid crystal element inserted in a longitudinal Kerr microscope is used as an optical modulator to acquire a reference image needed to enhance Kerr contrast by image processing. Domain images of the Nd-Fe-B magnet can be clearly observed by this technique in a high magnetic field up to 4.4 kOe. It was found that polishing of the sintered magnet reduced its coercive force.