Articles with confounded emission characteristics and methods and apparatus for their authentication

Abstract

Embodiments include articles, authentication methods and apparatus, and article manufacturing methods. An article includes a substrate with a first luminescent taggant, and an extrinsic feature with a second luminescent taggant, which is positioned proximate a portion of the article surface. The first and second taggants produce emissions in overlapping emission bands as a result of exposure to excitation energy. Above the extrinsic feature, the substrate and extrinsic feature emissions combine in the overlapping emission band to produce “confounded” emissions that are distinguishable from the substrate emissions taken alone. An authentication system determines whether, in a region corresponding to a “substrate-only” region of an authentic article, emissions having first emission characteristics are detected in the overlapping emission band. The system also determines whether, in a region corresponding to an “extrinsic feature” region of an authentic article, the confounded emissions are detected in the overlapping emission band.

1 . An article comprising:
 a substrate having a first surface and a first luminescent taggant, wherein the first luminescent taggant produces substrate emissions in a substrate emission band when the substrate is exposed to substrate excitation energy; and   an extrinsic feature positioned proximate a portion of the first surface at which the first luminescent taggant is present, wherein the extrinsic feature includes a second luminescent taggant that produces extrinsic feature emissions in an extrinsic feature emission band that at least partially overlaps the substrate emission band in an overlapping emission band when the extrinsic feature is exposed to extrinsic feature excitation energy,   wherein at the portion of the first surface, the substrate emissions and the extrinsic feature emissions combine in the overlapping emission band to produce confounded emissions that are distinguishable from the substrate emissions.   
     
     
         2 . The article of  claim 1 , wherein the substrate comprises a substrate material, and the first luminescent taggant is integrated into the substrate material. 
     
     
         3 . The article of  claim 1 , wherein the extrinsic feature comprises a composition applied to the first surface, and the second luminescent taggant is integrated into the composition. 
     
     
         4 . The article of  claim 1 , wherein the first luminescent taggant includes a first emitting ion, the second luminescent taggant includes the first emitting ion, and the substrate emissions and the extrinsic feature emissions are produced by the first emitting ion in the first and second luminescent taggants. 
     
     
         5 . The article of  claim 4 , wherein the first emitting ion is incorporated into the first luminescent taggant at a first doping density, and the first emitting ion is incorporated into the second luminescent taggant at a second doping density that is different from the first doping density. 
     
     
         6 . The article of  claim 4 , wherein the first luminescent taggant includes the first emitting ion substituted into a first host lattice, and the second luminescent taggant includes the first emitting ion substituted into a second host lattice that is different from the first host lattice. 
     
     
         7 . The article of  claim 4 , wherein the first luminescent taggant includes the first emitting ion in a first host material, and the second luminescent taggant includes the first emitting ion in the first host material. 
     
     
         8 . The article of  claim 1 , wherein the first luminescent taggant includes a first emitting ion, the second luminescent taggant includes a second emitting ion that is different from the first emitting ion, the substrate emissions are produced by the first emitting ion in the first luminescent taggant, and the extrinsic feature emissions are produced by the second emitting ion in the second luminescent taggant. 
     
     
         9 . The article of  claim 1 , wherein the article includes a supplemental ion that produces supplemental emissions in a supplemental emission band that does not overlap the substrate emission band or the extrinsic feature emission band when a taggant that includes the supplemental ion is exposed to a supplemental taggant excitation energy. 
     
     
         10 . The article of  claim 9 , wherein the supplemental taggant excitation energy is different from the substrate excitation energy and the extrinsic feature excitation energy. 
     
     
         11 . The article of  claim 9 , wherein the supplemental ion is included in the extrinsic feature. 
     
     
         12 . The article of  claim 9 , wherein the supplemental ion is included in the substrate. 
     
     
         13 . The article of  claim 9 , wherein the supplemental ion is included in a supplemental feature proximate a second portion of the first surface. 
     
     
         14 . The article of  claim 1 , wherein the second luminescent taggant includes one or more ions that produce supplemental emissions in a supplemental emission band that does not overlap the substrate emission band or the extrinsic feature emission band when the second luminescent taggant is exposed to a supplemental taggant excitation energy. 
     
     
         15 . The article of  claim 1 , wherein the substrate has a first substrate edge and a second substrate edge opposite the first substrate edge across the first surface, with a primary axis defined in a direction perpendicular to the first and second substrate edges, and wherein a first feature edge of the extrinsic feature is a first distance from the first substrate edge in a direction of the primary axis, a second feature edge of the extrinsic feature is a second distance from the second substrate edge in a direction of the primary axis, and wherein the second distance is different from the first distance to enable at least a partial determination of an orientation of the substrate. 
     
     
         16 . The article of  claim 15 , wherein the substrate has a second surface opposite the first surface, and the article further comprises:
 an additional extrinsic feature positioned proximate a portion of the second surface, wherein the additional extrinsic feature includes the second luminescent taggant, a third feature edge of the additional extrinsic feature is a third distance from the first substrate edge, a fourth feature edge of the additional extrinsic feature is a fourth distance from the second substrate edge, and wherein the first distance, the second distance, the third distance, and the fourth distance all are different from each other to enable a definitive determination of the orientation of the substrate.   
     
     
         17 . The article of  claim 1 , wherein the substrate emission band and the extrinsic feature emission band each independently correspond to an emission band of at least one ion of at least one element selected from a group of elements consisting of chromium, manganese, iron, cobalt, copper, silver, cerium, praseodymium, neodymium, samarium, europium, terbium, dysprosium, holmium, erbium, thulium, ytterbium, and combinations thereof. 
     
     
         18 . The article of  claim 1 , wherein the substrate emission band and the extrinsic feature emission band each independently correspond to an emission band of at least one ion after incorporation into a host material selected from a group consisting of an oxide, a fluoride, an oxysulfide, a halide, a borate, a silicate, a gallate, a phosphate, a vanadate, an oxyhalide, an aluminate, a molybdate, a tungstate, a garnet, a niobate, a nitride, an oxynitride, and combinations thereof. 
     
     
         19 . The article of  claim 1 , wherein the article is an article selected from a group consisting of an identification card, a driver's license, a passport, identity papers, a banknote, a check, a document, a paper, a stock certificate, a packaging component, a credit card, a bank card, a label, a seal, a postage stamp, a token, a liquid, a human, an animal, and a biological sample. 
     
     
         20 . A method for authenticating an article that includes a substrate, the method comprising the steps of:
 exposing a surface of the substrate to excitation energy;   determining whether, in a first region of the surface, first emissions having first emission characteristics are detected in a first emission band, wherein the first emissions result from the excitation energy, and the first region corresponds to a region at which an extrinsic feature is not present in an authentic article; and   determining whether, at a second region of the surface, second emissions having second emission characteristics that are different from the first emission characteristics are detected in the first emission band, wherein the second emissions result from the excitation energy, and the second region corresponds to a region at which the extrinsic feature is present in the authentic article.   
     
     
         21 . The method of  claim 20 , further comprising:
 identifying the article as being authentic when the first and second emissions are detected, and when the second emissions have the second emission characteristics; and   identifying the article as being unauthentic when the first emissions, the second emissions or both are not detected, or when the second emissions do not have the second emission characteristics.   
     
     
         22 . The method of  claim 21 , further comprising:
 determining a location of the second region with respect to the surface;   determining whether the location corresponds to a location of the extrinsic feature on the authentic article;   when the location of the second region corresponds to the location of the extrinsic feature, identifying the article as being authentic; and   when the location of the second region does not correspond to the location of the extrinsic feature, identifying the article as being unauthentic.   
     
     
         23 . The method of  claim 20 , wherein exposing the surface of the substrate to excitation energy comprises:
 exposing the surface to excitation energy at a wavelength that results in energy absorption by a first emitting ion of a first taggant incorporated into a substrate of an authentic article and that also results in energy absorption by a second emitting ion of a second taggant incorporated into an extrinsic feature of the authentic article.   
     
     
         24 . The method of  claim 20 , wherein exposing the surface of the substrate to excitation energy comprises:
 exposing the surface to excitation energy at a first wavelength that results in energy absorption by a first emitting ion of a first taggant incorporated into a substrate of an authentic article; and   exposing the surface to excitation energy at a second wavelength that results in energy absorption by a second emitting ion of a second taggant incorporated into an extrinsic feature of an authentic article, wherein the second wavelength is different from the first wavelength.   
     
     
         25 . The method of  claim 20 , wherein the second emission characteristics are different from the first emission characteristics in that a second emission intensity is perceptibly different from a first emission intensity. 
     
     
         26 . The method of  claim 20 , wherein the second emission characteristics are different from the first emission characteristics in that a second decay time constant is perceptibly different from a first decay time constant. 
     
     
         27 . The method of  claim 20 , wherein exposing the surface of the substrate to excitation energy comprises:
 exposing the surface to first excitation energy at one or more wavelengths that result in energy absorption by an emitting ion of a first taggant incorporated into the substrate of the authentic article and that result in energy absorption by an emitting ion of a second taggant incorporated into the extrinsic feature of the authentic article, and   exposing the surface to second excitation energy at a wavelength that results in energy absorption by a supplemental ion incorporated into the authentic article;   
       the method further comprises:
 determining whether supplemental emissions are detected in a second emission band that is different from the first emission band, wherein the supplemental emissions result from the second excitation energy. 
 
     
     
         28 . An apparatus for authenticating an article that includes a substrate, the apparatus comprising:
 one or more excitation energy generators configured to direct excitation energy toward a surface of the substrate;   a first emissions detector configured to detect first emissions in a first emission band; and   a processing system configured to determine whether, in a first region of the surface, first emissions having first emission characteristics are detected in a first emission band, wherein the first emissions result from the excitation energy, and the first region corresponds to a region at which an extrinsic feature is not present in an authentic article, and wherein the processing system is further configured to determine whether, at a second region of the surface, second emissions having second emission characteristics that are different from the first emission characteristics are detected in the first emission band, wherein the second emissions result from the excitation energy, and the second region corresponds to a region at which the extrinsic feature is present in the authentic article.   
     
     
         29 . The apparatus of  claim 28 , wherein the at least one excitation energy generator is configured to expose the surface of the substrate to excitation energy by exposing the surface to excitation energy at a wavelength that results in energy absorption by a first emitting ion of a first taggant incorporated into a substrate of an authentic article and that also results in energy absorption by a second emitting ion of a second taggant incorporated into an extrinsic feature of the authentic article. 
     
     
         30 . The apparatus of  claim 28 , wherein the at least one excitation energy generator is configured to expose the surface of the substrate to excitation energy by:
 exposing the surface to excitation energy at a first wavelength that results in energy absorption by a first emitting ion of a first taggant incorporated into a substrate of an authentic article; and   exposing the surface to excitation energy at a second wavelength that results in energy absorption by a second emitting ion of a second taggant incorporated into an extrinsic feature of an authentic article, wherein the second wavelength is different from the first wavelength.   
     
     
         31 . The apparatus of  claim 28 , wherein:
 the at least one excitation energy generator is configured to expose the surface of the substrate to excitation energy by exposing the surface to first excitation energy at one or more wavelengths that result in energy absorption by an emitting ion of a first taggant incorporated into the substrate of the authentic article and that result in energy absorption by an emitting ion of a second taggant incorporated into the extrinsic feature of the authentic article;   the at least one excitation energy generator is further configured to expose the surface to second excitation energy at a wavelength that results in energy absorption by a supplemental ion;   the apparatus further comprises a second emissions detector configured to detect emissions in a supplemental emission band that does not overlap the first emission band; and   the processing system is further configured to:
 determine whether, supplemental emissions are detected in a second emission band that is different from the first emission band, wherein the supplemental emissions result from the second excitation energy.