Possible technological steps needed to prepare semitransparent hologram foils for application in optical security documents were developed. Fabrication of master original includes two possibilities, laser direct imaging and mask photolithography. The suitability of both technologies and materials applied in them were analysed by the quality of replication and hot embossing.
F.09 Development of a new technological process or technology
COBISS.SI-ID: 4917786The possibilities for non-destructive identification of optically variable devices (OVD) applied in security printing were examined applying portable spectrogoniometer. Among OVDs highly prevails application of diffraction gratings and simple structures whach are deduced by their combinations. The limited number of measurement geometries applied in spectrogoniometer may therefore be questionable. We have shown that applying 19 geometries suitable data were obtained to form their fingerprint. The diffraction angles provide the direction of diffraction grooves. Reflectance spectra provide the geometrical parameters of diffraction structure. The plenty of data measured by spectrogoniometer is much more abundant than any kind of visual inspection which makes these methods very interesting to differentiate originals from fakes.
F.02 Acquisition of new scientific knowledge
COBISS.SI-ID: 4918042