Technology as unique fingerprint

A scanner with a low power focused laser beam scans across the surface of the item to be identified. The document or card is placed flat on the top of the scanner and pushed by hand until two of its edges press against guide rails. This ensures that the same part of the document is scanned each time. During the scan, the scanner records a large number of details of the way the laser light is reflected off the surface of the paper or plastic.

Microscopic irregularities on the surface due to the structure of the paper fibres or the setting of the plastic result in complex scattering of the laser beam, through the optical phenomenon of 'speckle'. This forms the basis of a signature which is unique to any given sheet of paper or plastic. The scanner is sufficiently sensitive to detect surface irregularities of less than a few hundred nanometers in size.

Genuine documents, cards and packaging would have their fingerprint read on the way out of the issuing agency or factory. The fingerprint is then stored either in a central database or is written onto the item using an encrypted barcode. In order to check the validity of the item later in the field, the fingerprint would be re-read and compared against the database or against the barcode.

The time required to acquire a fingerprint depends on whether the item to be scanned is already moving, as in a printing press or on a production line. In this case, linear speeds of up to 4 metres per second can be accommodated. If the item is static, then the scanning time is approximately 1 second.

Each fingerprint occupies between 125 and 750 bytes of storage space. The user can set the fingerprint size, according to how much redundancy against item damage is required.

Read more: Ingenia technology

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