Detection of counterfeit banknotes using a magneto-optical layer for detection of weak magnetic fields from the banknotes with detection improved by use of light propagating parallel to the magneto-optical layer

摘要

Device for examination of the magnetic properties of sheet material, such as banknotes (20), comprises a magneto-optical layer (10), whose optical properties are influenced by the magnetic field of the object, a light source (11) the light from which interacts with the magneto-optical layer and a detector (13) for detection of light transmitted or reflected from the magneto-optical layer. The arrangement of the components is such that the light propagates parallel to the base surface (9) of the magneto-optical layer. An Independent claim is made for a method for examining the magnetic properties of sheet material, such as banknotes.