Glossary

Printing ink containing metallic components that provide a metallic finish to the applied substrate.

The coating of films or surfaces with a very thin layer of metal using a metal deposition technique. Metallisation is what gives holograms their silver or similar metallic appearance.

A pair of similarly shaded inks, the colour and contrast of which appear virtually identical in normal light, but which have different spectral responses so that, when viewed in another light (such as infrared), one ink displays different effects or colours to the other. In the case of IR pairs, one ink absorbs IR and the other reflects it, and only the IR-reflecting part can be seen through a filter.

Thin 2D metamaterial layers that allow or inhibit the propagation of electromagnetic waves in desired directions.

An integrated circuit embedded into a recessed area on the surface of, for example, an ID card or passport to store and process personal data. A secure document containing a contact microchip must be inserted into a card reader so that the chip can make contact with electrical terminals and allow information to be read.

An integrated circuit embedded under the surface of, for example, an ID card or passport to store and process personal data. The microchip is connected to an aerial (electromagnetic loop antenna) which allows communication with a card reader via electromagnetic waves (RFID). To supply the microchip with energy and to start communication, the card must be in close proximity to the reader.

Small lenses, typically only a few microns in size.

Tiny microscopic mirrors created using origination techniques similar to those used for diffractive OVDs (optically variable devices). Micromirrors reflect light in a specific manner defined by the size and orientation of the mirrors.

A unit of measurement commonly used in authentication when referring to the thickness or gauge of physical substrates and features. One micron is equal to one millionth (10-6) of a metre.

Optical systems that are between a few micrometres (millionths of a metre) and one millimetre in size, including small lenses or arrays of lenses.

Lines, symbols, designs, images or numbers that are printed at dimensions barely perceptible to the unaided human eye but visible at magnifications of between x5 and x10 by (say) a jeweller’s loupe. Microprinting on banknotes usually combines positive and negative characters.

The very small scale structure of a prepared surface of a material as revealed by a microscope above 25× magnification. Diffractive microstructures comprise microprotrusions or microgrooves, or a combination thereof, which are capable of diffracting lightwaves.

A digital driving license held within, and presented from a mobile device.

A digital identity held within, and presented from a mobile device.

An app for storing financial information and other documents such as credit cards, bank information, and even driving licences.

Large-scale interference patterns produced when a partially opaque ruled pattern with transparent gaps is overlaid on another similar pattern. For the moiré interference pattern to appear, the two patterns must not be completely identical, but rather displaced, rotated, or have slightly different pitch.

A diffractive image in which different, usually unrelated images appear at different viewing angles. The most usual, and easiest to make, are images that flip from one to another as a DOVID is tilted from side to side. The most difficult is an image that changes as the DOVID is rotated.

A multistep account login process that requires users to enter more information than just a password. For example, along with the password, users might be asked to enter a code sent to their email, answer a secret question, or scan a fingerprint.

Captures image data within specific wavelength ranges across the electromagnetic spectrum. The wavelengths may be separated by filters or detected with the use of instruments that are sensitive to particular wavelengths, including light from frequencies beyond the visible light range (ie. infrared and ultraviolet). Multispectral imaging can allow extraction of additional information the human eye fails to capture with its visible receptors for red, green and blue. 

A unit of measurement commonly used in authentication when referring to the thickness or gauge of physical substrates and features. One nanometre is equal to one billionth (10-9) of a metre.

The science and technology of precisely manipulating the structure of matter at the atomic and molecular level. In the authentication sector, nanotechnology is used to explore and develop unique optical phenomena for use in new material and security features.

A foundational identification system that provides national IDs – often an identity document – and potentially other credentials. In many countries, a primary function of national ID systems has been to establish and provide recognition and proof of nationality and/or residency status.

A method of wireless data transfer between two electronic devices over a distance of 4cm or less.

The part of the electromagnetic spectrum between 780nm and 2500nm, near-infrared is the region closest in wavelength to the red light detectable by the human eye.

Light from the side, falling at a shallow angle, and revealing the surface structure of an object through contrasts of light and shade. Oblique light is used especially to inspect embossing stamps, intaglio printing, latent images and mechanical erasures.

An indirect printing process whereby ink is spread on a metal plate with etched images, then transferred to an intermediary surface such as a rubber blanket, and finally applied to the substrate by pressing that substrate against the intermediary surface. With wet offset, the printing plate must be moistened with water before it is inked, whereas dry offset printing does not use water. Offset is often used in long secure document print runs and is the most common printing method for tax stamps.

A method for identifying an unknown individual, via biometric data such as a photo of their face or fingerprints, which is compared to a larger database to uncover a potential match. 

The optical property of a substrate that prevents transmission of light.

The reading and recognition of characters using an optical device.

Overt and semicovert security features with dynamic characteristics that change according to the viewing angle – eg. from one colour to another, or from one image to another.

A popular type of secure printing ink that contains microscopic pigments acting as interference filters, resulting in large colour shifts determined by the angle of lighting or viewing.

Process to check security features visible with simple smartphone cameras, such as diffractive motion effects based on the viewing angle.

Allows static controls using cameras at multiple wavelengths (visible and infrared light).

The process which transforms an initial design of a banknote or security document into an industrial product ready for printing.

A single-run multicolour printing method invented by Ivan Orlov in 1890 in Russia. Consists of creating separate ink layers on colour-separated plates and transferring the inks to a common plate and then to the receiving surface.

Security features such as holograms that are apparent to the human senses – especially those of sight and touch – without the need for additional readers and instruments. Such features are designed to enable all stakeholders, including the public, to identify if something is genuine or not.

Name of a widely used colour matching system in graphic design, whereby each colour is coded with a reference number.

The phenomenon in an image which allows depth to be judged from the movement of near image elements relative to more distant ones. Traditional embossed holograms only display parallax from side to side, but the lack of vertical parallax is rarely noticed. Ortho-parallax is the term for when the movement of the elements is in a counterintuitive direction (ie. 90°) to the angle of view.

A security feature that requires an action such as scanning or photocopying to become visible. See also Active security feature.

This is the main document certifying a person’s identity and allowing them to cross a border. A passport is issued to all individuals who are citizens or permanent residents of a particular country. It consists of a small book with a hard or a soft cover. It contains the holder’s personal identifying information, security features, information about the issuing country and issuing authority, and blank pages for visas and other marks.

Visibly similar to iridescence but with a slightly ‘milky’ appearance at certain viewing angles.

In the context of ID, personalisation refers to the combination of biographical data, variable text and signature that are added to a document to render it unique and link it to the document holder.

The fraudulent practice of sending emails or other messages purporting to be from reputable companies in order to induce individuals to reveal personal information, such as passwords and credit card numbers.

A type of fluorescence that continues for a period of time after the stimulus that produced the emission has stopped.

A light-induced reversible colour change which in its most familiar form involves an ultraviolet-induced transformation from colourless to coloured. Sunglasses that darken in the sunlight and revert to near colourless in subdued light constitute the most widely known application of photochromism. However, there are a diverse range of other applications and potential applications that include fuel markers, security inks and electronic nanotechnology.

Luminescence produced by exposure to ultraviolet light.

Holograms produced from materials that polymerise (combine to form a polymer) under the action of light energy and thus change their refractive index. Used to record volume reflection holograms (see Volume hologram).

A light-sensitive material used in processes such as photolithography and photoengraving to form a patterned coating on a surface. A substrate is coated with a light-sensitive organic material. A patterned mask is then applied to the surface to block light, so only unmasked areas are exposed. A solvent, called a developer, is then applied to the surface. In the case of a positive photoresist, the photo-sensitive material is degraded by light and the developer dissolves away exposed areas, leaving a coating where the mask was placed. In the case of a negative photoresist, the photo-sensitive material is strengthened (either polymerised or cross-linked) by light, and the developer dissolves away areas not exposed to light, leaving a coating in areas where the mask was not placed. This process is used to create surface grating images, which are the first stage in producing embossed holograms.

A device that utilises the unique, random, physical variations which occur naturally in a physical structure and which provide that structure with a ‘fingerprint’ that serves as a unique identifier. See also Fingerprinting – document.

In digital imaging, a pixel (or picture element) is the smallest item of information in an image. Pixels are arranged in a 2D grid, represented by squares. Each pixel is a sample of an original image, with more samples typically providing more accurate representations of the original.