Stacking procedure for noise reduction in magneto-optical imaging

Magneto-optical effects are exploited for direct visualization of the magnetic field distribution in solid-state physics, in chemistry and in astrophysics. In this paper, we present a procedure for increasing the signal-to-noise ratio (S/N) in microscopic magneto-optical imaging of magnetic materials. The procedure consists of the repetitive measurement of the bi-dimensional magnetic field distribution and of custom routines for assembling the data. These routines use morphological operators for the alignment and the sum of the collected frames (stacking) and for discharging measurements affected by artefacts. The stacked image gains a S/N improvement equal to the square root of the number of selected frames. Also the pixel depth is increased by the same factor. The proposed stacking procedure is applied to the measurement of static magnetic field distributions of domain walls and magnetic vortices in garnet films.