An original document is formed using a first print medium by printing a first and second monochrome patterns with a single colorant to form printed first and second regions including first and second shapes, respectively, which are devoid of the colorant. The second shapes have a smaller size and a higher frequency than the first shapes. The first and/or second regions encode information. The first and second patterns and a fluorescence of the first print medium are selected such that the first and second regions of the original document are indistinguishable to the naked eye, under both normal and ultraviolet illumination but are distinguishable, only under the ultraviolet illumination, in a copy formed by scanning the original document and printing the scanned document on a second print medium with a plurality of colorants, to reveal the encoded information.

A plasmonic structure having an identifier pattern indicating a genuine product for preventing counterfeiting, falsification or reuse, includes a metal layer; a photoconversion pattern layer including a plurality of photoconverting nanoparticles disposed in a pattern on and in direct contact with the metal layer; a metal pattern layer including a plurality of metal particles disposed in a pattern on and in direct contact with the photoconversion pattern layer; and an adhesive film disposed on the metal pattern layer. An identifier pattern indicating a genuine product is easily identified even by visual inspection after irradiation with infrared light irradiation. The plasmonic structure is fundamentally impossible to re-assemble after deformation of the plasmonic structure caused by disassembly of a product or packaging container, thereby preventing counterfeiting, falsification or reuse.

Security of a printed matter is enhanced, and a visual image is made to clear if a latent image formed by a coat printed on a matter to be printed for a security enhancement of the printed matter becomes the visual image. A security ink pigment contains a powder. A main constituent of the powder is a perovskite-type oxide. The perovskite-type oxide has a composition expressed as a general formula of ABO.sub.3. A is mainly made of Ba. B is mainly made of Sn. The powder emits infrared fluorescence when being irradiated with ultraviolet excitation light. The perovskite-type oxide has a crystal lattice constant having a difference equal to or smaller than 0.002 angstrom from a theoretical crystal lattice constant of the perovskite-type oxide having a composition expressed as a composition formula of BaSnO.sub.3.

A system and method for treatment of thread includes a thread printer that applies colored coatings to thread and that passes the treated thread to a fabric weaving system. A camera is positioned to capture images of the treated thread as it is woven into a fabric in the fabric weaving system. The system processes the images to determine whether the location of a selected segment of the treated thread in the fabric corresponds to an expected location in the fabric. If the actual location of the selected segment corresponds to the expected location, the system will continue instructing the thread printer to selectively apply the colored coatings to the thread according to the pattern. However, if the actual location does not correspond to the expected location, the system will modify the pattern so that thread printer adjusts the size of a segments to automatically account for the misalignment.

Disclosed are optical devices suitable as security devices for document authentication, which comprise at least one two-dimensional array of elongate laser-modified tracks extending within a document substrate that have a distinct optical refractive index compared to the unmodified substrate, which can exhibit excellent diffractive effects. Also disclosed are the use of such devices for document authentication and methods for their production.

Security of a printed matter is enhanced, a coat printed on a matter to be printed for a security enhancement of the printed matter is printed by a normal printing process, and the coat is flattened and smoothed. A security ink pigment contains a powder. A main constituent of the powder is a perovskite-type oxide. The perovskite-type oxide has a composition expressed as a general formula of ABO.sub.3. A is mainly made of Ba. B is mainly made of Sn. A median diameter of the powder is equal to or smaller than 10 m. The powder emits infrared fluorescence when being irradiated with ultraviolet excitation light.

An aqueous colored pigment-based ink that is capable of fluorescence, has a pigment colorant in an amount of 1-7 weight %; a non-polymeric fluorophore that when excited by fluorescence-exciting radiation having a peak of at least 200 nm and up to and including 400 nm, exhibits an emission peak of at least 400 nm and up to and including 750 nm, and which non-polymeric fluorophore is present in an amount of 0.1-2 weight %; and an aqueous medium comprising water. This aqueous colored pigment-based ink can be included in an ink set that also includes one or more aqueous colored pigment-based inks that are non-fluorescent. All of these inks can be applied using continuous inkjet (CIJ) printing, onto non-UV fluorescent substrates to provide images that can be detected when excited as noted above, which images can be provided on articles such as security documents, currency, and lottery tickets.

An aqueous colored pigment-based ink that is capable of fluorescence, has a pigment colorant in an amount of 1-7 weight %; a non-polymeric fluorophore that when excited by fluorescence-exciting radiation having a peak of at least 200 nm and up to and including 400 nm, exhibits an emission peak of at least 400 nm and up to and including 750 nm, and which non-polymeric fluorophore is present in an amount of 0.1-2 weight %; and an aqueous medium comprising water. This aqueous colored pigment-based ink can be included in an ink set that also includes one or more aqueous colored pigment-based inks that are non-fluorescent. All of these inks can be applied for example using inkjet printing, onto non-UV fluorescent substrates to provide images that can be detected when excited as noted above, which images can be provided on articles such as security documents, currency, and lottery tickets.

A UV curable inkjet ink containing covert or overt ultraviolet or infrared reactive material. The ultraviolet or infrared reactive materials are processed in acrylate monomer or combination of acrylate monomer and acrylate oligomer media, along with photoinitiators and surfactants to produce an inkjet ink for printing on non-porous substrates such as plastic, glass, ceramic or metal with high adhesion, scratch and chemical resistance and providing a security feature responsive to ultraviolet or infrared radiation.

The absorbance or emission wavelength of composite materials comprising a transition metal doped shell disposed over a rare earth doped core and a functionalizable group on the surface of the transition metal doped shell can change upon subjection to a carboxylic acid. This method of changing the absorbance or emission wavelength of a composite material can be used to identify counterfeit currency using an ink comprising a composite material.