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Indian Journal of Pure & Applied Physics (IJPAP) >
IJPAP Vol.42 [2004] >
IJPAP Vol.42(11) [November 2004] >
| Title: | Interferometry based security hologram readable with an encoded key hologram |
| Authors: | Aggarwal, A K
Kaura, Sushil K
Sharma, Amit K
Kumar, Raj
Chhachhia, D P |
| Keywords: | Security holograms
Holograms
Optical security |
| Issue Date: | Nov-2004 |
| Publisher: | CSIR |
| IPC Code: | G 02B 5/32 |
| Abstract: | A simple and cost-effective
method for making security holograms has been presented, which incorporates
holographic interferometry as verification feature in addition to spatially
separated sharp focus spots. When the security hologram is illuminated with
decoding reconstructing beam generated from an encoded key hologram, two
spatially separated sharp focus spots emerge at the predefined positions and
can be read through a photoelectric detector array. In addition, these focused
spots upon divergence in longitudinal direction further generate specific kind
of interferometric fringe patterns of random profile contained in them, which
are suitable for further visual inspection. These machine-readable and visual
verifiable features can be used for better counterfeit-resistant security codes
in embossed holograms. Recording schemes for the formation of such security
holograms and typical experimental results have been presented. |
| Page(s): | 816-819 |
| ISSN: | 0975-1041 (Online); 0019-5596 (Print) |
| Source: | IJPAP Vol.42(11) [November 2004]
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