We imaged magnetic domains in Pt/Co/Pt multilayers using an apertureless sc
anning near-field optical microscope operating in reflection mode. As the m
agneto-optical effects are weak for this kind of structure, a polarization
modulation technique with a photoelastic modulator was used to reveal the c
ontrast between magnetic domains. In the case of a Pt/Co/Pt trilayer struct
ure, a strong improvement in lateral resolution is observed compared with f
ar-field magneto-optical images and good sensitivity is achieved. In the ca
se of a Pt/[Co/Pt]Pt multilayer structure, stripe domains of 200 nm width c
ould be resolved, in good agreement with images obtained by magnetic force
microscopy on the same structure.