Everyday Documents Protected with Infrared Technology

Michael A. Greenwood

For those who want to protect everyday documents such as tickets, deeds and licenses against forgery, there have not been a lot of effective or affordable options. Highly sophisticated security features, such as those used in currency and passports, are too expensive, not to mention complex, for regular use.

Recently released technology from Xerox Corp. of Norwalk, Conn., may provide the answer by allowing documents printed with everyday toners and on standard color digital printing equipment to be protected against forgery. It embeds patterns or text in regular paper that can be read only with infrared light.

An invention by Xerox Corp. makes it possible to print variable text that is detectable only under infrared light. Principal scientist Raja Bala, a co-inventor of the technology, holds a camera that captures the infrared image and displays it on the computer monitor. Infrared printing is a low-cost way to secure or authenticate documents. Courtesy of Xerox and Kevin Rivoli.

The technology relies on certain optical characteristics of printing colorants — toners, inks, dyes —that enable two colorant mixtures to appear the same under normal light but different under infrared light, said Raja Bala, co-inventor of the technique and a principal scientist for the company. For example, in many color laser printers, the black toner is carbon-based, and thus absorbs infrared light, while the other colored toners — cyan, magenta and yellow — do not absorb infrared light.

It is thus possible to find two toner mixtures — one with a small amount of black and the other with a large amount of black — that are indistinguishable under normal light but very distinct under infrared light.

If the protected document is copied or altered, the encoded text will appear substantially distorted when placed under an infrared light source. Practically any infrared light source and sensor can be used to detect the embedded text.

The patented InfraRedMark technology is designed to work with ordinary materials and can be used on the company’s standard digital printing systems. It is available in the FreeFlow Variable Information Suite 6.0 software.

Xerox also has developed other anticounterfeiting technology within the past year, including text that is printed smaller than a 1 point size, that is visible as a gloss effect when the paper is tilted, that is revealed by ultraviolet light or that is visible when an overlay key is superimposed.