A magneto-optical microscope for quantitative measurement of magnetic microstructures

An optical system is presented to quantitatively map the stray magnetic fields of microscale magnetic structures, with field resolution down to 50 mu T and spatial resolution down to 4 mu m. The system uses a magneto-optical indicator film (MOIF) in conjunction with an upright reflective polarizing light microscope to generate optical images of the magnetic field perpendicular to the image plane. A novel single light path construction and discrete multi-image polarimetry processing method are used to extract quantitative areal field measurements from the optical images. The integrated system including the equipment, image analysis software, and experimental methods are described. MOIFs with three different magnetic field ranges are calibrated, and the entire system is validated by measurement of the field patterns from two calibration samples. (C) 2015 AIP Publishing LLC.