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Proceedings Paper

Synthetic double-exposure method for security holograms: image estimation based on numerical simulation
Author(s): Nobukazu Yoshikawa; Masahide Itoh; Toyohiko Yatagai
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Paper Abstract

We have developed a synthetic double exposure (SDE) method of the computer-generated holograms (CGHs) for security applications. This method is based on incoherent multiplexing of two types of coding methods on binary CGHs: a cell-oriented and a point-oriented. The CGH synthesized by the SDE can have multiple image planes from the image region to the Fraunhofer region. In fabrication process of the SDE, the point-oriented CGH, that is, the image-type hologram is erased slightly by the cell-oriented CGH. We estimate here the image quality and the diffraction efficiency of the reconstructed image in the image-type hologram by the SDE using numerical simulations. In our simulations, the cell-oriented CGH occupied only 14% of the entire hologram area. The diffraction efficiency of the image-type hologram by the SDE was about 80%. Therefore, the information of the image-hologram was preserved sufficiently. The CGH including image-, Fresnel- and Fourier-type holograms was fabricated using the direct writing of electron-beam resist in electron-beam lithography. These reconstructed images were almost identical to the desired ones.

Paper Details

Date Published: 7 May 1999
PDF: 4 pages
Proc. SPIE 3740, Optical Engineering for Sensing and Nanotechnology (ICOSN '99), (7 May 1999); doi: 10.1117/12.347733
Show Author Affiliations
Nobukazu Yoshikawa, Univ. of Tsukuba (Japan)
Masahide Itoh, Univ. of Tsukuba (Japan)
Toyohiko Yatagai, Univ. of Tsukuba (Japan)


Published in SPIE Proceedings Vol. 3740:
Optical Engineering for Sensing and Nanotechnology (ICOSN '99)
Ichirou Yamaguchi, Editor(s)

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