A method of marking an article for authentication, the comprising the steps of applying an identification mark to an article, said mark comprising an array of varying sized markings, where the combination of the shape, the spatial distribution and the varying sizes of the markings imparts a distinctiveness to the identification mark recording the identification mark in a database and associating information relating to the article with the identification mark in the database, wherein comparison of the identification mark on the article and the database enables the identification mark to be associated with the information relating to the article on the database.

A physical payment card includes hidden features (e.g., textual messages, graphics, emphasis features associated with conspicuous features of the payment card, or the like) undiscernible under only visible light, but discernable under ultraviolet light. A digital version of the physical card can be established on a user device. During setup, the user device can receive data regarding the hidden features that are associated with the physical card. Under a normal state, the user device can display the digital card without displaying the hidden features. However, upon activation (e.g., when the digital card is used, when the physical card is used, when the physical card is in sufficient proximity, or the like), the user device can display the hidden features on the digital card.

A physical payment card includes hidden features (e.g., textual messages, graphics, emphasis features associated with conspicuous features of the payment card, or the like) undiscernible under only visible light, but discernable under ultraviolet light. A digital version of the physical card can be established on a user device. During setup, the user device can receive data regarding the hidden features that are associated with the physical card. Under a normal state, the user device can display the digital card without displaying the hidden features. However, upon activation (e.g., when the digital card is used, when the physical card is used, when the physical card is in sufficient proximity, or the like), the user device can display the hidden features on the digital card.

A substrate can include an optical light guide including a core. The core can include a fluorescent material in a content of greater than 0.5 wt. % for the total weight of the core. In an embodiment, the optical light guide can include a scintillator material. In another embodiment the core can include polyethylene naphthalate (PEN) and a polyvinylidene difluoride cladding.

According to examples, a substrate may be moved through a magnetic field, in which the substrate includes a fluid carrier containing magnetically-orientable flakes. The magnetic field may influence the magnetically-orientable flakes to be respectively oriented in one of multiple orientations. In addition, during movement of the substrate through the magnetic field, radiation may be applied onto a plurality of selected portions of the fluid carrier through at least one opening in a mask to cure the fluid carrier at the plurality of selected portions and fix the magnetically-orientable flakes in the plurality of selected portions at the respective angular orientations as influenced by the magnetic field.

Techniques are described to embed graphical identifiers into a ghost image within a layer of laminate of an identification document. The ghost image includes optically variable media that has a first appearance when viewed from a front of the identification document in reflected light at a first angle and a second, different appearance when viewed from the front of the identification document in reflected light in a second, different angle. During the ghost image generation process, a graphical identifier can be placed on a baseline ghost image to generate an adjusted ghost image. Once the adjusted ghost image is printed onto the identification document, the graphical identifier can be viewable based on the appearance of the adjusted ghost identifier in relation to the reflected light.

Techniques are described to embed graphical identifiers into a ghost image within a layer of laminate of an identification document. The ghost image includes optically variable media that has a first appearance when viewed from a front of the identification document in reflected light at a first angle and a second, different appearance when viewed from the front of the identification document in reflected light in a second, different angle. During the ghost image generation process, a graphical identifier can be placed on a baseline ghost image to generate an adjusted ghost image. Once the adjusted ghost image is printed onto the identification document, the graphical identifier can be viewable based on the appearance of the adjusted ghost identifier in relation to the reflected light.

There is provided a holographic security element including a substrate; and an array of nano-reflectors configured to form a pattern on the substrate and to generate a holographic image corresponding to the pattern at a predetermined distance from the substrate when irradiated with a predetermined light source. In particular, the array of nano-reflectors is configured to generate the holographic image at the predetermined distance to have a size that is larger than a size of the pattern. There is also provided a method of forming the holographic security element, and an article having one or more holographic security elements incorporated therein.

There is provided a holographic security element including a substrate; and an array of nano-reflectors configured to form a pattern on the substrate and to generate a holographic image corresponding to the pattern at a predetermined distance from the substrate when irradiated with a predetermined light source. In particular, the array of nano-reflectors is configured to generate the holographic image at the predetermined distance to have a size that is larger than a size of the pattern. There is also provided a method of forming the holographic security element, and an article having one or more holographic security elements incorporated therein.

The present invention relates to a method of tagging a substrate with a covert, spectroscopically detectable security feature, wherein a liquid treatment composition comprising at least one acid is deposited onto a substrate, which comprises at least one external surface comprising a salifiable alkaline or alkaline earth compound.