Security hologram

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A hologram on a Nokia mobile phone battery. This is intended to show the battery is 'original Nokia' and not a cheaper imitation. Nokia Battery Hologram.jpg
A hologram on a Nokia mobile phone battery. This is intended to show the battery is 'original Nokia' and not a cheaper imitation.
A hologram label on a paper box for security GatewayTracingHologramLabel.jpg
A hologram label on a paper box for security

Security holograms are labels with a hologram printed onto it for sale security reasons.

Contents

It is argued by the International Hologram Manufacturers Association that holograms on security labels are difficult to forge because they are replicated from a master hologram which requires expensive specialized and technologically advanced equipment. [1] However, security holograms have also been criticised for their ineffectiveness, because equipment for manufacturing holograms has become significantly easier to access, and because few people have the expertise and equipment to authenticate them accurately. [2]

Security holograms are used widely in several banknotes around the world, in particular those that are of high denominations. They are also used in passports, credit and bank cards as well as quality products.

Holograms are classified into different types with reference to the degree of level of optical security incorporated in them during the process of master origination. The different classifications are described below:

2D / 3D "hologram" images

Hologram image against counterfeit on a traveller's cheque from American Express, c. 2012. The image has one of the company's symbols on it, a soldier with an old-style helmet. Four Travelers Cheques of 50 USD each, issued by American Express, bought ca. 2012, have long been spent.jpg
Hologram image against counterfeit on a traveller's cheque from American Express, c. 2012. The image has one of the company's symbols on it, a soldier with an old-style helmet.

These are by far the most common type of hologram – and in fact they are not holograms in any true sense of the words.[ citation needed ] The term "hologram" has taken on a secondary meaning due to the widespread use of a multi-layer image on credit cards and driver licenses. This type of "hologram" consists of two or more images stacked in such a way that each is alternately visible depending upon the angle of perspective of the viewer. The technology here is similar to the technology used for the past 50 years to make red safety night reflectors for bicycles, trucks, and cars.[ citation needed ]

These holograms (and therefore the artwork of these holograms) may be of two layers (i.e. with a background and a foreground) or three layers (with a background, a middle ground and a foreground). In the case of the two-layer holograms, the matter of the middle ground is usually superimposed over the matter of the background of the hologram. These holograms display a unique multilevel, multi-color effect. These images have one or two levels of flat graphics “floating” above or at the surface of the hologram. The matter in the background appears to be under or behind the hologram, giving the illusion of depth.

Dot matrix

These holograms have a maximum resolution of 10 micrometers per optical element and are produced on specialized machines making forgery difficult and expensive.[ citation needed ] To design optical elements, several algorithms are used to shape scattered radiation patterns.

Flip flop

Flip-flop hologram master origination is a technique used to produce holograms that display flip-flop effect.[ jargon ] They are produced with a 2D/3D master shooting system. This two channel effect of 2D/3D holograms displays two different images from different angles. These holograms are often fabricated using supreme quality material.[ citation needed ] The final master obtained from this flip-flop mastering technique are used to manufacture holograms which gives flip-flop effects. Having an excellent blend of 2D/3D and flipping images offers holographic images an excellent depth and a dazzling appeal.[ promotion? ]

Electron-beam lithography

These types of holograms are created using highly sophisticated and very expensive electron-beam lithography systems. This kind of technology allows the creation of surface holograms with a resolution of up to 0.1 micrometers (254,000 dpi).[ citation needed ] This technique requires development of various algorithms for designing optical elements that shapes scattered radiation patterns. This type of hologram offers features like the viewing of four lasers at a single point, 2D/3D raster text, switch effects, 3D effects, concealed images, laser readable text and true color images.

The various kinds of features possible in security holograms are mentioned below:

Concealed images

These usually take the form of very thin lines and contours. Concealed images can be seen at large angle light diffraction, and at one particular angle only.

Guilloché patterns (high resolution line patterns)

These are sets of thin lines of a complicated geometry (guilloché patterns) drawn with high resolution. The technology allows continuous visual changes of color along each separated lines.

Kinetic images

They can be seen when the conditions of hologram observations are being changed. Turning or inclining the hologram allows the movements of certain features of the image to be studied.

Microtexts or nanotexts

Dot matrix holograms are capable of embedding microtext at various sizes. There are three types of microtexts in holograms:[ citation needed ] high contrast microtexts of size 50 – 150 micrometres; diffractive grating filled microtexts of size 50 – 150 micrometres low contrast microtexts. Microtexts of sizes smaller than 50 micrometres are referred to as nanotext. Nanotext with sizes of less than 50 micrometres can be observed with a microscope only.

Covert laser readable images

Dot matrix holograms also support covert laser readable (CLR) imagery, where a simple laser device may be used to verify the hologram's authenticity. Computing CLR images is a complicated mathematical task that involves solving ill-posed problems.[ citation needed ] There are two types of CLR: Dynamic CLR and Multigrade CLR. Dynamic CLR is a set of CLR fragments that produce animated images on the screen as the control device moves along the hologram surface. Multigrade CLR images produce certain images on the screen of the controlling device, which differ in the first and minus first orders of laser light diffraction.[ jargon ] As a variant, a hidden image which is both negative and positive, in plus one and minus one order respectively, may be created.[ jargon ]

More recently, novel computer-generated holograms have been proposed working with structured light carrying phase singularities. [3] Such optical elements further improve the security level, since the encoded information only appears when the input illumination is endowed with the correct intensity and phase distribution.

Computer-synthesized 2D/3D and 3D images

This technology allows 2D / 3D images to be combined with other security features (microtexts, concealed images, CLR etc.) This combination effect cannot be achieved using any other traditional technologies of origination.[ citation needed ] 2D/3D hologram masters are developed in 2D/3D master shooting lab that incorporates highly sensitive machines and advanced equipment such as microprocessor-controlled automatic positioning equipment, optical table, He-Cd laser, laser power controller, silver coatings and other related technologies. The final master obtained from 2D/3D mastering is used to manufacture 2D/3D hologram stickers. These stickers consist of a multitude of two-dimensional layers with images placed one behind the other thereby offering excellent depth.[ promotion? ] These stickers are colorful images with 3D depth between different layers.

True color images

True color images are very effective decorative pictures. When synthesized by a computer, they may include microtexts, hidden images, and other security features, yielding attractive, high-security holograms.[ promotion? ] True Color hologram masters can be produced using 2D/3D master shooting system. The final master obtained from this mastering technique comprises true photographic images like images of people, animals, flags, etc. This type of holograms can't be duplicated if in case they can't obtain the original photo.[ citation needed ] True color holograms are one of the best ways to prevent counterfeiters from duplicating.[ citation needed ]

See also

Related Research Articles

<span class="mw-page-title-main">Microscopy</span> Viewing of objects which are too small to be seen with the naked eye

Microscopy is the technical field of using microscopes to view objects and areas of objects that cannot be seen with the naked eye. There are three well-known branches of microscopy: optical, electron, and scanning probe microscopy, along with the emerging field of X-ray microscopy.

<span class="mw-page-title-main">Holography</span> Recording to reproduce a three-dimensional light field

Holography is a technique that enables a wavefront to be recorded and later reconstructed. It is best known as a method of generating three-dimensional images, and has a wide range of other uses, including data storage, microscopy, and interferometry. In principle, it is possible to make a hologram for any type of wave.

<span class="mw-page-title-main">Stereoscopy</span> Technique for creating or enhancing the impression of depth in an image

Stereoscopy is a technique for creating or enhancing the illusion of depth in an image by means of stereopsis for binocular vision. The word stereoscopy derives from Greek στερεός (stereos) 'firm, solid' and σκοπέω (skopeō) 'to look, to see'. Any stereoscopic image is called a stereogram. Originally, stereogram referred to a pair of stereo images which could be viewed using a stereoscope.

<span class="mw-page-title-main">Security printing</span> Field of the printing industry for banknotes and other security products

Security printing is the field of the printing industry that deals with the printing of items such as banknotes, cheques, passports, tamper-evident labels, security tapes, product authentication, stock certificates, postage stamps, and identity cards. The main goal of security printing is to prevent forgery, tampering, or counterfeiting. More recently many of the techniques used to protect these high-value documents have become more available to commercial printers, whether they are using the more traditional offset and flexographic presses or the newer digital platforms. Businesses are protecting their lesser-value documents such as transcripts, coupons and prescription pads by incorporating some of the features listed below to ensure that they cannot be forged or that alteration of the data cannot occur undetected.

<span class="mw-page-title-main">3D display</span> Display device

A 3D display is a display device capable of conveying depth to the viewer. Many 3D displays are stereoscopic displays, which produce a basic 3D effect by means of stereopsis, but can cause eye strain and visual fatigue. Newer 3D displays such as holographic and light field displays produce a more realistic 3D effect by combining stereopsis and accurate focal length for the displayed content. Newer 3D displays in this manner cause less visual fatigue than classical stereoscopic displays.

A volumetric display device is a display device that forms a visual representation of an object in three physical dimensions, as opposed to the planar image of traditional screens that simulate depth through a number of different visual effects. One definition offered by pioneers in the field is that volumetric displays create 3D imagery via the emission, scattering, or relaying of illumination from well-defined regions in (x,y,z) space.

<span class="mw-page-title-main">Confocal microscopy</span> Optical imaging technique

Confocal microscopy, most frequently confocal laser scanning microscopy (CLSM) or laser scanning confocal microscopy (LSCM), is an optical imaging technique for increasing optical resolution and contrast of a micrograph by means of using a spatial pinhole to block out-of-focus light in image formation. Capturing multiple two-dimensional images at different depths in a sample enables the reconstruction of three-dimensional structures within an object. This technique is used extensively in the scientific and industrial communities and typical applications are in life sciences, semiconductor inspection and materials science.

<span class="mw-page-title-main">Optical neural network</span> Physical implementation of an artificial neural network with optical components

An optical neural network is a physical implementation of an artificial neural network with optical components. Early optical neural networks used a photorefractive Volume hologram to interconnect arrays of input neurons to arrays of output with synaptic weights in proportion to the multiplexed hologram's strength. Volume holograms were further multiplexed using spectral hole burning to add one dimension of wavelength to space to achieve four dimensional interconnects of two dimensional arrays of neural inputs and outputs. This research led to extensive research on alternative methods using the strength of the optical interconnect for implementing neuronal communications.

<span class="mw-page-title-main">Holographic data storage</span> Data storage technology

Holographic data storage is a potential technology in the area of high-capacity data storage. While magnetic and optical data storage devices rely on individual bits being stored as distinct magnetic or optical changes on the surface of the recording medium, holographic data storage records information throughout the volume of the medium and is capable of recording multiple images in the same area utilizing light at different angles.

Computer-generated holography (CGH) is a technique that uses computer algorithms to generate holograms. It involves generating holographic interference patterns. A computer-generated hologram can be displayed on a dynamic holographic display, or it can be printed onto a mask or film using lithography. When a hologram is printed onto a mask or film, it is then illuminated by a coherent light source to display the holographic images.

<span class="mw-page-title-main">3D optical data storage</span> Storage with three-dimensional resolution for information

3D optical data storage is any form of optical data storage in which information can be recorded or read with three-dimensional resolution.

Volume holograms are holograms where the thickness of the recording material is much larger than the light wavelength used for recording. In this case diffraction of light from the hologram is possible only as Bragg diffraction, i.e., the light has to have the right wavelength (color) and the wave must have the right shape. Volume holograms are also called thick holograms or Bragg holograms.

<span class="mw-page-title-main">Laser beam profiler</span> Measurement device

A laser beam profiler captures, displays, and records the spatial intensity profile of a laser beam at a particular plane transverse to the beam propagation path. Since there are many types of lasers—ultraviolet, visible, infrared, continuous wave, pulsed, high-power, low-power—there is an assortment of instrumentation for measuring laser beam profiles. No single laser beam profiler can handle every power level, pulse duration, repetition rate, wavelength, and beam size.

<span class="mw-page-title-main">Microlens</span> Small lens, generally with a diameter less than a millimetre

A microlens is a small lens, generally with a diameter less than a millimetre (mm) and often as small as 10 micrometres (μm). The small sizes of the lenses means that a simple design can give good optical quality but sometimes unwanted effects arise due to optical diffraction at the small features. A typical microlens may be a single element with one plane surface and one spherical convex surface to refract the light. Because micro-lenses are so small, the substrate that supports them is usually thicker than the lens and this has to be taken into account in the design. More sophisticated lenses may use aspherical surfaces and others may use several layers of optical material to achieve their design performance.

A holographic display is a type of 3D display that utilizes light diffraction to display a three-dimensional image to the viewer. Holographic displays are distinguished from other forms of 3D displays in that they do not require the viewer to wear any special glasses or use external equipment to be able to see the image, and do not cause a vergence-accommodation conflict.

<span class="mw-page-title-main">Holographic weapon sight</span> Type of gunsight

A holographic weapon sight or holographic diffraction sight is a non-magnifying gunsight that allows the user to look through a glass optical window and see a holographic reticle image superimposed at a distance on the field of view. The hologram of the reticle is built into the window and is illuminated by a laser diode.

Holographic optical element (HOE) is an optical component (mirror, lens, directional diffuser, etc.) that produces holographic images using principles of diffraction. HOE is most commonly used in transparent displays, 3D imaging, and certain scanning technologies. The shape and structure of the HOE is dependent on the piece of hardware it is needed for, and the coupled wave theory is a common tool used to calculate the diffraction efficiency or grating volume that helps with the design of an HOE. Early concepts of the holographic optical element can be traced back to the mid-1900s, coinciding closely with the start of holography coined by Dennis Gabor. The application of 3D visualization and displays is ultimately the end goal of the HOE; however, the cost and complexity of the device has hindered the rapid development toward full 3D visualization. The HOE is also used in the development of augmented reality(AR) by companies such as Google with Google Glass or in research universities that look to utilize HOEs to create 3D imaging without the use of eye-wear or head-wear. Furthermore, the ability of the HOE to allow for transparent displays have caught the attention of the US military in its development of better head-up displays (HUD) which is used to display crucial information for aircraft pilots.

An optical variable device or optically variable device (OVD) is an iridescent or non-iridescent security feature that exhibits different information, such as movement or colour changes, depending on the viewing and/or lighting conditions. The particular changes of appearance when rotating and tilting are reversible, predictable and reproducible. OVDs cannot be photocopied or scanned, nor can they be accurately replicated or reproduced. OVDs are often used as security devices and anti-counterfeiting measures on banknotes, government-issued identification documents, or credit cards. OVDs can be created through a combination of printing and embossing.

Optical holography is a technique which enables an optical wavefront to be recorded and later re-constructed. Holography is best known as a method of generating three-dimensional images but it also has a wide range of other applications.

A diffractive optically variable image device (DOVID) is a type of optical variable device; a security feature based on visual effects created by diffraction. The acronym was coined by Ian Lancaster of Reconnaissance International in 1995. He pointed out that the security print industry was wary of holograms and similar diffractive devices because they were used as decorative, promotional and toy items, proposing the use of DOVID as a means to differentiate security diffractive optical devices from these other uses.

References

  1. "How holograms can stop counterfeiting". Packaging Digest. 2008-07-31. Retrieved 2020-05-04.
  2. Graham, Marty (2007-02-07). "Fake Holograms a 3-D Crime Wave". Wired. ISSN   1059-1028 . Retrieved 2020-05-04.
  3. Ruffato, Gianluca; Rossi, Roberto; Massari, Michele; Mafakheri, Erfan; Capaldo, Pietro; Romanato, Filippo (2017). "Design, fabrication and characterization of Computer Generated Holograms for anti-counterfeiting applications using OAM beams as light decoders". Scientific Reports. 7 (1): 18011. arXiv: 1708.01108 . Bibcode:2017NatSR...718011R. doi:10.1038/s41598-017-18147-7. PMC   5740128 . PMID   29269750.