Authentication systems for discriminating value documents based on variable luminescence and magnetic properties

An authentication system for discriminating a value document, comprising:

• a) a value document substrate;
• b) a luminescent compound disposed on or in at least a portion of the value document substrate, wherein the luminescent compound (i) comprises a host lattice having at least one metallic ion with magnetic properties and is doped with at least one rare earth ion capable of emitting infrared radiation when excited with an exciting light source and (ii) has a pre-determined ratio of the metallic ions to the rare earth ions capable of emitting infrared radiation when excited with an exciting light source such that the pre-determined ratio corresponds to a parameter of a pre-selected decision criterion, wherein the parameter is chosen from emissions, magnetism, absorption, and decay times;
• c) at least one optical sensor arranged to detect, with spectral resolution, infrared radiation emitted from the luminescent compound excited by the exciting light source and to produce intensity data;
• d) at least one magnetic sensor arranged to detect the magnetic properties of the luminescent compound and to produce magnetic data;
• and
• e) a processing unit operating under a predefined program wherein the processing unit correlates the intensity data and the magnetic data for the value document, compares the intensity data with previously stored reference intensity data and the magnetic data with previously stored reference magnetic data, derives an authenticity indicator from the comparisons using the pre-selected decision criteria, and communicates the authenticity indicator thereby indicating authentication or lack of authentication of the value document.