Beneath The Surface: Internal Fingerprint Sensors
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The Optical Society (OPA) reports that scientists from The Langevin Institute, Paris, France, have constructed a new fingerprint imaging system that peers inside the finger to take a picture — a more reliable and secure way of identifying individuals. Importantly, the device is also simpler, faster, and cheaper than other technology used previously to image inside fingers. The researchers report their results in the journal Biomedical Optics Express, from the Optical Society (OSA).
Most optical fingerprint sensors today produce images by reflecting light from areas where the skin does not come in contact with a glass plate, a technique that captures details from only the very top layer of skin. In contrast, this new device images the “internal fingerprints,” which have the same pattern as external fingerprints, but are about half a millimeter below the skin’s surface.
The new sensor uses a special variant of an imaging technology called optical coherence tomography (OCT). OCT is already used for medical imaging and works by analyzing an interference pattern created when a beam of light that travels through a biological sample, like a finger, is recombined with a reference beam of light.
The main advantage of the system is that it can take a 2D image of the fingerprint directly, saving time and making the data processing simpler and cheaper. Because not everyone’s internal fingerprints are located at the same depth, the researchers also developed a method to first take an image of the fingertip at an angle. The first image was used to determine the depth of the internal fingerprint, and then a second image of the fingerprint itself was taken.
The team has plans to soon test the device in Turkey, where 100 people will have their fingerprints scanned. They are also working to further improve the imaging speed and depth capabilities of the system.
