INVISIBLE WRITING METHOD BASED ON LUMINESCENT MATERIALS LITHOGRAPHY, RELEVANT READING METHOD AND ANTI-COUNTERFEITING MARKING SYSTEM

摘要

The invention concerns an invisible writing method based on lithography of luminescent materials, characterised in that: one irradiates a luminescent material (11 ), i.e. a photostimulable luminescence material, by means of soft X-rays or EUV ionising radiation (13) beam with spectral energy lower than 400 eV, in such a way to form on the material a trace of colour centres corresponding to a pre-determined image, the irradiation takes place with a density DIof radiant energy, incident on said luminescent material, comprised between 0.01 J/cm2 and 3 J/cm2, and with a dose DA comprised between 0.1 kJ/cm3 and 2000 kJ/cm3, such an irradiation density value DI and dose DA being suitable to create a colour centres density such that said image is visible only when irradiated by light radiation of excitation of the same colour centres in the relevant absorption band. The invention further concerns a relevant method for the reading of invisible images imprinted by luminescent materials lithography, as well as relevant anti-counterfeiting/tracking marking system and reading device to be used in such a system, and a structured luminescent material particularly suited for anti-counterfeiting purposes.