摘要 |
An article is marked with image indicia for authentication, information, or decoration by providing a plurality of inks having a plurality of fluorescence colors when exposed to excitation energy, separating colors of the image indicia into a plurality of image levels in accordance with the fluorescence colors of the inks, and printing each image level in mutual registration on the article using the corresponding ink. The image printed with each ink may be substantially invisible under illumination within the visible spectrum. The invisibly printed images have multiple authentication features, including the use of covert UV-fluorescent materials, IR-fluorophores, microparticles, and other chemical taggants. Ink compositions, methods for making the inks, and methods and apparatus for using the inks are also disclosed.
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