COUNTERFEIT PROTECTION OF PLASTIC BANKNOTES USING A HOLOGRAPHIC IMAGE OF VERIFIABLE AUTHENTICITY

摘要

The invention relates to special types of printing and makes it possible to protect plastic banknotes against counterfeit by means of a holographic image. In the claimed method, a protective holographic image is created on a laser-transparent plastic intended for the production of banknotes. By means of embossing, two diffraction gratings are applied, one opposite the other, to the opposing surfaces of the plastic, said gratings being embedded in the plastic. One of the gratings is embedded in the plastic such that a layer of metal can be applied thereto, and the other grating is embedded such that a layer of metallized foil can be applied thereto above a layer of metal. As a result of the interaction of pulses of laser radiation with the metallized foil and with both diffraction gratings, a set of four interrelated images is created in the plastic for the production of banknotes: a holographic image and an image comprised of the inlet openings of channels produced by the pulses of laser radiation are created on the surface of the metallized foil; images comprised of demetallized regions on the gratings, said regions being coaxial with the openings of the channels in the metallized foil, are created on the diffraction gratings; a hidden image is created in the channels in the metallized foil, said hidden image being comprised of pairs of three-dimensional nanostructures, the excitation and irradiation of which results in the appearance of a holographic image.