KERR-ROTATION IMAGING IN SCANNING NEAR-FIELD OPTICAL MICROSCOPY USINGA MODIFIED SAGNAC INTERFEROMETER

A scanning near-field optical microscope is combined with a modified S agnac interferometer to generate high-resolution magnetic contrast ima ges of a magneto-optical disk (MOD) in reflection. The interferometer acts as a magnetic sensor to determine the Kerr rotation of reflected circularly polarized light. A separate shear-force sample topography i s obtained simultaneously with the optical. This technique allows succ essful magnetic imaging of samples with complicated surface topographi es, as demonstrated with the MOD. For these initial measurements, the resolution with nonmetal-coated fiber tips is 300 nm, and the magnetic phase sensitivity is I mrad, (C) 1998 American Institute of Physics.