FIELD: special types of printing.
SUBSTANCE: invention relates to special types of printing and allows to protect against counterfeit plastic banknote with holographic image, authenticity of which is easily checked by complex of public protective features associated with created holographic image. According to the proposed method, the protective holographic image is created directly on the plastic transparent for laser radiation, intended for the banknotes manufacturing. Two diffraction gratings recessed inside the plastic are applied on the opposite surfaces of the plastic. One of the grates is recessed into plastic with possibility of application of metal layer on it, and the other grid is embedded into plastic with possibility of application on it above metal layer of metalized foil. As a result of interaction of laser radiation pulses with metalized foil and both diffraction gratings, in plastic for making banknotes, a complex of four interconnected images is created: on the surface of the metal-coated foil – a holographic image and an image from the inlet openings of channels created by laser radiation pulses; on diffraction gratings – images from demetallized sections on these grates, coaxial with holes of channels in metalized foil; in channels in metallized foil – hidden image from pairs of volumetric nanostructures, excitation and illumination of which causes appearance of holographic image. In order to check, it is sufficient to deflect the banknote with the holographic image created on it from the light source, thus preventing its passage into the channels in the metalized foil for excitation and illumination of pairs of volumetric nanostructures, then on the metallized foil the holographic image is replaced by the image from the inlet openings of the channels in this foil. Very fact of such replacement confirms that the holographic image on the banknote is genuine. In transmitted light, the original holographic image also disappears and an image from demetallized areas on the diffraction gratings appears instead.
EFFECT: disclosed is a method of protecting a plastic banknote from counterfeiting.
3 cl, 4 dwg
