Patent ID: 8742369
Filing Date: 2014-06-03
Classification: G07D

Abstract:
1. A method of authenticating a value document or other article using an authentication apparatus, the method comprising the steps of: a) providing the value document or other article to the authentication apparatus, the value document or other article comprising at least one taggant having a crystal lattice doped with a first rare earth active ion; b) applying radiation having a first wavelength to the value document or other article from an illumination source of the authentication apparatus for an illumination duration; wherein the taggant absorbs the radiation and emits infrared radiation having a second wavelength that is greater than the first wavelength of the radiation, the emitted infrared radiation having a maximum intensity that occurs at a delay period measured from the end of the illumination duration, the delay period being greater than about 0.1 millisecond; c) detecting intensity of the emitted infrared radiation as a function of time with a sensor of the authentication apparatus to produce emission data; and d) processing the emission data with a processor of the authentication apparatus to determine whether the value document or other article is authentic, wherein the processing includes identifying the maximum intensity of the emitted infrared radiation that occurs after the delay period.