Fingerprints scanners have a slight problem: many of them cannot tell whether they’re scanning an actual finger, silicon casts, latex rubber models or patterns made on Gummi Bear candies.

Even the variations in real skin can trick the devices. Some Asians, people with very dry or moist skin, elderly people and manual laborers with rough hands are frequently blocked by the electronic gatekeepers.

Cross Match, in Palm Beach Gardens, Fla., and Lumidigm, have developed technologies that let scanners analyse the pattern of blood vessels below the skin’s surface, as well as the internal structure of the skin itself.

Lumidigm’s device aims the light from L.E.D.’s directly at the skin. The diodes illuminate the skin at five different wavelengths and the light is polarized to penetrate the skin.

Each of the different wavelengths of light travel a different distance into the skin before being reflected back to the reader’s digital camera. After five pictures have been taken, software analyzes how the wavelengths of light were changed by their trip through the skin and calculates the finger’s “spectral signature.”

Cross Match system is different, it sees what happens to extremely high-frequency sound waves when they make a similar journey.

Via Ubergizmo The New York Times.