Glossary

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.

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 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.

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.

Tobacco products other than cigarettes, such as cigars and pipe tobacco.

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.

In computing and telecommunications, the payload is the part of transmitted data that is the actual intended message.

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

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.

The illegal reproduction and distribution of copyright material, generally taken to be audio and video content.

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.

A coloured or reflective disc containing a security feature and embedded in paper during manufacture.

The alignment of the electric and magnetic fields in a particular orientation in a lightwave. If all the waves in a beam of light move up and down or from side to side together, the beam is said to be plane-polarised. Some materials have the ability to filter out all lightwaves except those in a particular direction. Other materials are said to be optically active if they are able to change the angle of a plane-polarised beam of light. Liquid crystals often have this property and this enables them to be detected.

An optical device which transforms unpolarised light into polarised light. It is used to examine light reflected from ink or thin-film coating. It blocks light rays of a specific polarisation direction while letting light rays of other polarisation directions pass.

A thermoplastic polymer resin of the polyester family, used to make the most common container in the soft drink market today: the plastic bottle. Also used as the base material for most surface-applied holograms and security threads.

A substance or material consisting of very large molecules, or macromolecules, composed of many repeating subunits. Plastic and polyester are all polymers. Polymer banknotes were first introduced in Australia and are widely used around the world.

A laboratory technique for rapidly producing (amplifying) millions to billions of copies of a specific segment of DNA, which can then be studied in greater detail.

A stacked linear barcode format used in a variety of applications such as transport, identification cards, and inventory management. The ‘417’ signifies that each pattern in the code consists of 4 bars and spaces in a pattern that is 17 units (modules) long.

Preparatory work required on original materials, such as films, files and plates to carry out the printing of a banknote or other security document.

A label construction made up of three layers: a face material, a pressure-sensitive adhesive, and a backing sheet coated with a release agent. Pressure-sensitive labels only need the pressure of a hand to be applied to an item.

In colour printing, print registration is the layering of printed patterns to form a multicolour image. Registration error refers to position misalignment in overlapped patterns, resulting in printed colours in the wrong areas, overprint or white space.

A plant for producing banknotes and other security documents. Printworks can be either state or central bank-owned or run by commercial companies.

The overprinting of two or more coloured inks to create a blended colour affect that is difficult to match on copiers. Prismatic colour blending is visually similar to split fountain printing, but differences become apparent when the images are magnified.

An automated system installed on product manufacturing lines, using sensors and scanners to provide tax authorities and other government agencies with full visibility on what is being produced and ensure that every production unit has been affixed with a valid unique identifier, tax stamp, or secure label.

A set of policies, processes, server platforms, software, and workstations used for administering public key certificates and public-private key pairs, including the ability to issue, maintain, and revoke certificates.