Concealed moiré pattern encoded security holograms readable by a key hologram

Aggarwal, A. K.; Kaura, Sushil K.; Chhachhia, D. P.; Sharma, Amit

doi:10.1016/j.optlastec.2004.10.010

Cited by 35 publications

(19 citation statements)

References 12 publications

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“…Almost, every country has opted for protection against fake currencies by either use of holographic techniques or by use of visible luminescent ink or bands and so on (which glow under ultraviolet (UV) light). [6][7][8][9][10] Furthermore, commercial and industrial sectors, particularly those producing branded goods and pharmaceuticals, have also adopted these techniques and have benetted tremendously from these safety measures against counterfeiting. 11,12 Besides this, another area of security where a more overt colorimetric indicator can be used is food security, where sensing the presence of oxygen is a principal goal -the area of intelligent packaging.…”

Section: Introductionmentioning

confidence: 99%

Highly luminescent dual mode rare-earth nanorod assisted multi-stage excitable security ink for anti-counterfeiting applications

2014

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In this paper, the synthesis of multi-stage excitable (379 nm, 980 nm and 1550 nm), highly luminescent3+ nanorods by a hydrothermal method which can emit both hypersensitive green (562 nm) and strong red (660 nm) in a single host lattice and which can be used for a transparent security ink application is reported. Furthermore, these luminescent nanorods also exhibit both down-shift (1127 nm) as well as upconversion (562 nm) features at a single excitation near infrared wavelength of 980 nm. The characterization of these luminescent nanorods was explored by studying their structure/microstructure, using photoluminescence and time-resolved spectroscopic techniques. Furthermore, these luminescent nanorods exhibited the tuning of emission colours from red to green by controlling the sintering temperature. It was demonstrated that these novel luminescent nanorods offer new opportunities for making high-end, multi-stage excitable transparent security ink. The state-of-art production process of ink is easy and it is most suitable for bulk production at an economical cost. Thus, the security inks could be used globally in applications for protection against counterfeiting.

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Section: Introductionmentioning

confidence: 99%

Highly luminescent dual mode rare-earth nanorod assisted multi-stage excitable security ink for anti-counterfeiting applications

2014

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“…Hologram is one of the most important optical massive information capacity element. Moiré patterns [4][5][6] have been proposed to improve the recognition capacity between counterfeits and originals as encode tools in different optical systems. In the present work digital Fourier transform holography is used to produce sinusoidal interferometric moirelike patterns.…”

Section: Introductionmentioning

confidence: 99%

Digital holographic moiré pattern for optical numerical code generation

Oliveira

Freire

et al. 2014

SPIE Proceedings

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In the present paper low frequency moiré fringe patterns are used as secure numerical code generator. These moiré patterns are experimentally obtained by the superposition of two sinusoidal gratings with slightly different pitches. The Bi 12 TiO 20 photorefractive crystal sample is used as holographic medium An optical numerical base was defined with patterns representing 0,1 and -1 digits like bits. Then, the complete set of these optical bits are combined to form bytes, where a numerical sequence is represented. The results show that the proposed numerical code could be used as standard numerical identification in robotic vision or in transmition of security numerical keys.

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Section: Introductionmentioning

confidence: 99%

Photorefractive moiré like pattern as optical numerical code generator

Oliveira

Santos

2012

SPIE Proceedings

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In the present letter low frequency moiré fringe patterns are used as secure numerical code generator. These moiré patterns are experimentally obtained by the superposition of two sinusoidal gratings with slightly different pitches. The Bi 12 TiO 20 photorefractive crystal sample is used as holographic medium An optical numerical base was defined with patterns representing 0,1 and -1 digits like bits. Then, the complete set of these optical bits are combined to form bytes, where a numerical sequence is represented. The results show that the proposed numerical code could be used as standard numerical identification in robotic vision or in transmition of security numerical keys.

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Concealed moiré pattern encoded security holograms readable by a key hologram

Cited by 35 publications

References 12 publications

Highly luminescent dual mode rare-earth nanorod assisted multi-stage excitable security ink for anti-counterfeiting applications

Highly luminescent dual mode rare-earth nanorod assisted multi-stage excitable security ink for anti-counterfeiting applications

Digital holographic moiré pattern for optical numerical code generation

Photorefractive moiré like pattern as optical numerical code generator

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