The Latent Image and its Role in Document Security

Huber, Reinhold

doi:10.1080/00085030.1977.10756841

Cited by 4 publications

(2 citation statements)

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“…The term "latent image" [11] denotes a developed printing technique based on the features of offset printing from engraved plates, on the basis of which it is possible to create "hidden" and "transient" images, and the optical principles based on which they work.…”

Section: State-of-the-artmentioning

confidence: 99%

An Approach towards the Protection for Printed Documents by Means of Latent Elements with Fractal Grids and Electronic Determination of Its Authenticity

et al. 2020

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An electronic method of protection for printed documents based on which latent elements are formed in a printed way has been developed. The development of security features has been done electronically. Protection using latent elements has been improved by overlapping fractal grids, which allows creation of graphics traps. The printing of designed security elements has been investigated on 15 paper samples. The security elements were printed on an offset printing machine. Prints were copied and compared with originals using the electronic method of pixel-by-pixel comparison based on a peak signal-to-noise ratio (PSNR). The comparison results between originals and their copies are presented in this paper.

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Section: State-of-the-artmentioning

confidence: 99%

An Approach towards the Protection for Printed Documents by Means of Latent Elements with Fractal Grids and Electronic Determination of Its Authenticity

et al. 2020

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“…The demand for reliable anti-counterfeiting methods is increasing to cope with the continuous attack of fraud. , Traditional printing-based optical anti-counterfeiting methods such as intaglio, guilloché, and latent images allow nonexperts to easily detect forgeries. In addition to these print-based anticounterfeit technologies, chemical-based security inks and optically variable devices (OVDs) have been developed to introduce tunability to the devices. − Tunable security inks, such as luminescent ink, metameric ink, and thermochromic ink, utilize the chemical characteristics of inks to achieve their sensitivity.…”

Section: Introductionmentioning

confidence: 99%

Metasurface-Driven Optically Variable Devices

et al. 2021

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Optically variable devices (OVDs) are in tremendous demand as optical indicators against the increasing threat of counterfeiting. Conventional OVDs are exposed to the danger of fraudulent replication with advances in printing technology and widespread copying methods of security features. Metasurfaces, two-dimensional arrays of subwavelength structures known as meta-atoms, have been nominated as a candidate for a new generation of OVDs as they exhibit exceptional behaviors that can provide a more robust solution for optical anti-counterfeiting. Unlike conventional OVDs, metasurfacedriven OVDs (mOVDs) can contain multiple optical responses in a single device, making them difficult to reverse engineered. Well-known examples of mOVDs include ultrahighresolution structural color printing, various types of holography, and polarization encoding. In this review, we discuss the new generation of mOVDs. The fundamentals of plasmonic and dielectric metasurfaces are presented to explain how the optical responses of metasurfaces can be manipulated. Then, examples of monofunctional, tunable, and multifunctional mOVDs are discussed. We follow up with a discussion of the fabrication methods needed to realize these mOVDs, classified into prototyping and manufacturing techniques. Finally, we provide an outlook and classification of mOVDs with respect to their capacity and security level. We believe this newly proposed concept of OVDs may bring about a new era of optical anticounterfeit technology leveraging the novel concepts of nano-optics and nanotechnology.

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Four-channel display and encryption by near-field reflection on nanoprinting metasurface

Cao

Tang

et al. 2022

Nanophotonics

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Multichannel metasurfaces become one of the most significant development trends, as they exhibit versatile manipulation abilities on electromagnetic fields and provide a promising approach to constitute compact devices with various complex functions, especially in optical encryption due to its capabilities of multichannel, high complexity, and high concealment. However, the existent multichannel metasurfaces based optical encryption technology can only realize two channels in the near-field, or perform three channels in near- and far-field. In this paper, a four-channel display metasurface used to encrypt information by three optical parameters as security keys is firstly proposed and experimentally demonstrated, which is different from the previous three-channel metasurface combined nanoprinting and hologram in near- and far-field. The novel design strategy of the four-channel metasurface can effectively enhance the information capacity and increase the difficulty of leaks without causing manufacturing challenges and additional costs. In addition, the simulation and experimental results demonstrate that the designed metasurface with four independent channels can separately display distinguishable nanoprinting images under decoding keys of special optical parameters. The proposed four-channel display metasurface with advantages of high capacity and ultracompactness will pave a way for multichannel applications in nano display, information storage, optical anticounterfeiting, and other relevant fields.

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The Latent Image and its Role in Document Security

Cited by 4 publications

References 0 publications

An Approach towards the Protection for Printed Documents by Means of Latent Elements with Fractal Grids and Electronic Determination of Its Authenticity

An Approach towards the Protection for Printed Documents by Means of Latent Elements with Fractal Grids and Electronic Determination of Its Authenticity

Metasurface-Driven Optically Variable Devices

Four-channel display and encryption by near-field reflection on nanoprinting metasurface

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