METHOD FOR MEASURING THE BASIC PARAMETERS OF DIGITAL SECURITY HOLOGRAMS FOR THE EXPERT ANALYSIS AND REAL-TIME CONTROL OF THEIR QUALITY
V. P. Bessmeltsev, V. V. Vileiko, M. V. Maksimov
Institute of Automation and Electrometry, Siberian Branch, Russian Academy of Sciences, Novosibirsk, Russia
Keywords: дифракционная решётка, голопиксель, цифровая голограмма, контроль подлинности, diffraction grating, holopixel, digital hologram, identity verification
Abstract
A method and a device are developed for measuring the basic parameter of synthesized security holograms with the use of capabilities of microscopy with micro-size resolution and diffractometry with a multiangular system of illumination. Based on consecutive illumination of the hologram surface by collimated monochromatic light sources at different angles in the field of vision of a special digital microscope and subsequent processing of the resultant images, an information map of the surface is formed, which contains information on the basic parameters of "holopixels" forming the structure of the security hologram (pitch of diffraction gratings, their angular orientation, and normalized intensity of reflected light), as well as the image of the hologram surface in scattered light matched with this map. By moving the hologram under consideration in the focal plane of the digital microscope to a distance equal to the field of vision of the microscope with subsequent matching of the data obtained, it is possible to construct the information map of the entire hologram surface with micron resolution.
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