Enhancement of magneto-optical domain observation by digital image processing

An electronic system is described which allows to subtract contrast of non-magnetic origin from a magneto-optic image. At the same time image noise can be reduced to such a degree that the contrast visibility limit in domain observation is expanded by at least an order of magnitude. The system is demonstrated for a number of applications in which domain analysis was not possible before. These include magnetostriction-free metallic glasses, non-oriented silicon-iron steel and polycrystalline Ni-Fe samples. For the first time the internal wall structure could be made visible on metallic samples with magneto-optical means.