Fingerprint scanners use different types of sensors to create digital images of the minutiae. Some commercially used sensors include optical, capacitance and ultrasonic. The technology used by them to capture the digital image varies and each one has its own share of merits & demerits. From all the sensors mentioned above, optical sensors’ technology is the most developed and thus is used widely in the fingerprint readers worldwide. Most of the fingerprint scanners distributed by us for biometric identification use optical sensor technology to achieve the best results.
As the name suggests, an optical scanner makes use of visible light (photons) to create multiple fingerprint patterns (minutiae). In that sense, its working mechanism is quite similar to what is used in the high-end digital cameras and camcorders. The glass surface on which the finger is placed is known as the touch surface and right beneath it is a layer of phosphor which is responsible for illuminating the touch surface (finger) for digital capture. The light reflected from the finger which contains the minutiae information in the form of photons consequently passes through the phosphor layer onto a charge-coupled device (CCD). Without going much into the physics of it, essentially, a CCD converts these photons into electrons and force them to pass to a place where the stored information (minutiae) in them is transformed into digital images.
Optical sensors offer many advantages over the capacitive sensors and therefore enjoy wider recognition from the biometric industry. Other than intermittent cleaning of the touch surface, optical sensors do not require much maintenance; whereas, capacitive sensors require constant surface protection from electrostatic discharge (ESD). Electrostatic discharge refers to the abrupt flow of electricity between the two electrically charged materials which may result in a high voltage static discharge. This high voltage static discharge could permanently damage the sensor. Also, optical sensors are more economical and provide larger imaging surface area with higher resolution and bigger image size (pixels). We make sure that our fingerprint scanners for biometric identification are in compliance with the best industry standards when it comes to digital imaging.