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20 February 2007 Problem of twin-image elimination in 2-D computer synthesized hologram
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It is well known that one of the basic functions of security holograms is the maximal complication of their nonauthorized reproduction, in other words - counterfeiting. To solve the problem, concealed images that can be observed only under special conditions are placed into a structure of the hologram. A popular way to place concealed image in Diffractive Optical Variable Device (DOVID) is integration into DOVID's structure of a Concealed Laser-Readable Image (CLRI). Traditionally CLRI is a 2-D Computer-Generated Hologram (2-D CGH), which is a digitized Interference Fringe Data (IFD) structure, computed under the scheme of Fourier-hologram synthesis. Such hologram provides inspection of second level with portable laser reading devices. While it is being read, two (+/- 1 order of diffraction) identical images are formed. In this work a special kind of CGH, which restores image only in one diffractive order or two different images in +1 and -1 orders of diffraction proposed.
© (2007) COPYRIGHT Society of Photo-Optical Instrumentation Engineers (SPIE). Downloading of the abstract is permitted for personal use only.
Eugene Braginets, Vladimir Girnyk, Sergey Kostyukevych, Alexander Soroka, and Irina Androsyuk "Problem of twin-image elimination in 2-D computer synthesized hologram", Proc. SPIE 6488, Practical Holography XXI: Materials and Applications, 64880D (20 February 2007);


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