Imaging Components, Systems, and Processing

Anticounterfeiting method for a dot-matrix hologram composed of grating dots with different fringe orientations

[+] Author Affiliations
Sheng Lih Yeh

Lunghwa University of Science and Technology, Department of Mechanical Engineering, 300, Sec. 1, Wanshou Road, Kueishan Taoyuan County 33306, Taiwan

Shyh Tsong Lin

National Taipei University of Technology, Department of Electro-Optical Engineering, 1, Sec. 3, Chung-Hsiao East Road, Taipei 10608, Taiwan

Opt. Eng. 54(11), 113106 (Nov 16, 2015). doi:10.1117/1.OE.54.11.113106
History: Received July 19, 2015; Accepted October 16, 2015
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Abstract.  A method for identifying a dot-matrix hologram composed of grating dots with different fringe orientations is proposed. Two neighboring grating dots, Dot 1 and Dot 2, are selected. The intersection angle between the two sets of fringes of the two grating dots must be smaller than a threshold angle, e.g., 50 deg. The overlapping region of Dot 1 and Dot 2 can show a moiré pattern composed of many stripes. Some of the stripes contain the same fringe orientation as that of Dot 1, some of the stripes contain the same fringe orientation as that of Dot 2, and some of the stripes contain special fringe orientations different from those of Dot 1 and Dot 2. The stripes which contain special fringe orientations are called transition stripes here, and the number of transition stripes (transition stripe number) is used to identify Dot 1 and Dot 2. Because the transition stripe number for a dot pair is sensitively affected by the distance between the dot pair and the grating brightness distributions of the two dots, it is difficult to correctly reproduce the transition stripe numbers for the grating dot pairs on a dot-matrix hologram, i.e., counterfeiting the hologram is not easy.

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© 2015 Society of Photo-Optical Instrumentation Engineers

Citation

Sheng Lih Yeh and Shyh Tsong Lin
"Anticounterfeiting method for a dot-matrix hologram composed of grating dots with different fringe orientations", Opt. Eng. 54(11), 113106 (Nov 16, 2015). ; http://dx.doi.org/10.1117/1.OE.54.11.113106


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