Image contrast in polarization microscopy of magneto-optical media through plastic substrates

Summary form only given. Using polarized light microscopy, we have observed the magnetic domains of perpendicularly magnetized media under different conditions, including direct observation of the thin-film magnetic layer, and observations through the glass or plastic substrate on which the magnetic film has been deposited. The results show that image contrast is reduced with increasing numerical aperture (NA) of the objective lens. They also indicate that the polarization rotation caused by differences between reflectivity/transmissivity of the p- and s-components of polarization deteriorate the magnetic image contrast.