Described is a chiral liquid crystal polymer (CLCP) layer or pattern which comprises randomly distributed craters of controlled mean diameter and/or density. The density and/or mean diameter of the craters can be controlled, for example, by adjusting the wetting of a substrate by a CLCP precursor composition, the development time of the precursor composition, and the thickness of the applied precursor composition.

A document which may be a security document has a thermochromic coating which may be a thermochromic ink on the substrate of the document. The ink may include several thermochromic materials which transition from various different colors to substantially clear in appearance as the ink is warmed to various temperatures. The combination of the colors of the thermochromic materials can give the document a different color at a number of different temperatures, until the coating is warmed to the highest color change point. When at or above the highest color change temperature, the coating becomes substantially transparent and the printed area assumes the color of the underlying substrate. The coating may also include non-reactive materials of yet another color that mixes with the colors of the thermochromic materials. The document may additionally include printed indicia on the substrate that are masked by the thermochromic materials at certain temperatures, and not masked by the thermochromic materials at other temperatures.

A security device including an array of lines printed or otherwise provided on a substrate, the lines including materials which have the same appearance under visible light illumination but which appear different from each other in the visible under a combination of visible and non-visible, ultraviolet illumination. At least some of the lines in the array appear different from other lines under the combination of visible and non-visible, ultraviolet illumination. A second, surface relief array of lines imposed on the first array, the orientation, line widths and spacings of the first and second arrays being such that the device exhibits a variable appearance as it is tilted while exposed to the combination of visible and non-visible illumination.

A method for checking, in particular the authenticity and/or the nominal value of a value document having luminescent feature substances, comprises: a1) the step of carrying out a location-specific measurement of first luminescence intensities at a first emission wavelength at different locations of the value document that have the location coordinates, to thereby obtain measurement value pairs; b1) the step of statistically analyzing the first luminescence intensities measured in dependence on the individual location coordinates, by determining at least one statistical parameter using a statistical method; and c1) the step of comparing the statistical parameter determined in the step b1) with one or more threshold values.

A thermochromic ink composition includes, in a liquid medium, known as solvent, a dispersion of thermochromic microcapsules incorporating at least one leuco-dye and a thermoplastic binder selected from the group containing polyacrylic polyesters, polyurethanes and copolymers thereof. The composition is characterized in that the solvent is aprotic. A a method for producing a card and such a card incorporating at least one thermochromic pattern produced with a thermochromic ink composition are also described.

The present invention relates to the use of nanosystems as non deactivable security markers comprising metal atomic quantum clusters (AQCs) of at least two different size distributions encapsulated in a cavity with an inner diameter less than or equal to approximately 10 nm. These nanosystems are luminescence, particularly fluorescence after external excitation. The invention also relates to security documents, articles or elements incorporating these markers as well as to a method and a system for detecting the same.

A security mark is produced on a micro-porous, synthetic paper, structure by changing light transmission properties of light pathways through the structure. The security mark is visible when the structure is illuminated.

A nanoparticle sized between 10-180 nm composed of M(III).sub.2O.sub.3, M(II)O and M(II)M(III).sub.2O.sub.4, wherein M(III) is a trivalent metal and M(II) is a divalent metal, or Fe.sub.2O.sub.3, MnO and M(II)O, wherein M is a divalent metal selected from the group consisting of Fe, Ni, Co, Cu, Pt, Au, Ag, Ba and a rare earth metal.

A secure product, and a production method, comprising a first reflective layer, a second layer and a third layer including readable information, the first layer being enclosed between the second and the third layers, in which the first and second layers are transparent, at least a first part of the internal surface of the second layer comprises a diffusing microstructure, and the diffusing microstructure is positioned so as to cover a predetermined part of the readable information.

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.