Disclosed herein are devices that change their appearance and/or physical properties when under an external influence, and methods for their production and use. Such devices may be used as features of any type of items, documents, billboards, posters, display devices, advertisements and other items etc. and may be adapted to include decipherable content. Such devices also afford new techniques for a user to check quickly and easily whether the item is a legitimate or a counterfeit copy, either by hand-manipulation of the device, or with the assistance of an additional screening tool.

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.

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.

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.

Methods of marking paper products and marked paper products are provided. Some methods include irradiating the paper product to alter the functionalization of the paper.

The present invention relates to a method of manufacturing a substrate with an embedded, UV-visible pattern, wherein a liquid treatment composition comprising at least one acid is deposited onto a substrate, which comprises at least one optical brightener and optionally a filler, wherein the filler comprises 0 to 60 wt.-% of a salifiable alkaline or alkaline earth compound, based on the total weight of the substrate.

The present invention relates to a method of manufacturing a substrate with an embedded, UV-visible pattern, wherein a liquid treatment composition comprising at least one acid is deposited onto a substrate, which comprises at least one optical brightener and optionally a filler, wherein the filler comprises 0 to 60 wt.-% of a salifiable alkaline or alkaline earth compound, based on the total weight of the substrate.

The present invention describes methods and apparatuses for creating superposition shape images by superposed base and revealing layers of lenslet gratings. The superposition shape images form a message recognizable by a human observer or by an image acquisition and computing device such as a smartphone. The superposition shape images may be created by different superposition techniques ranging from 1D moir, 2D moir and level-line moir superposition techniques to lenticular image and phase shift superposition techniques. Moir superposition techniques enable creating superposition shape images at different apparent depth levels. Applications comprise the protection of documents and valuable articles against counterfeits, the creation of eye-catching advertisements as well as the decoration of buildings and exhibitions.

The present invention describes methods and apparatuses for creating superposition shape images by superposed base and revealing layers of lenslet gratings. The superposition shape images form a message recognizable by a human observer or by an image acquisition and computing device such as a smartphone. The superposition shape images may be created by different superposition techniques ranging from 1D moir, 2D moir and level-line moir superposition techniques to lenticular image and phase shift superposition techniques. Moir superposition techniques enable creating superposition shape images at different apparent depth levels. Applications comprise the protection of documents and valuable articles against counterfeits, the creation of eye-catching advertisements as well as the decoration of buildings and exhibitions.

A forgery prevention structure, in one configuration, includes a relief forming layer, a first reflection layer, a functional thin film layer, a second reflection layer and a protection layer in this order. In this configuration, the relief forming layer has a relief structure comprising a first relief and a second relief; each of the reliefs has an uneven surface, a surface area of the uneven surface of the first relief being smaller than a surface area of the uneven surface of the second relief; the first reflection layer and the functional thin film layer each are provided along a whole of the uneven surfaces of the reliefs and each has uneven surfaces corresponding respectively to the uneven surfaces of the reliefs; and the second reflection layer and the protection layer each has an uneven surface corresponding to the uneven surface of the first relief.