Fingerprint reader as a means of authenticating a user

To date, the computerization of society makes it necessary to seek various ways to restrict access to information stored on a computer. And the system of authorization and user authentication by password is one of the most common, although it has many shortcomings. An alternative to password protection can be authentication based on the biometric parameters of the user, in particular by fingerprint. And this requires only a fingerprint scanner and the corresponding software that comes with the device.

What is a fingerprint scanner ?

The fingerprint reader is a device that reads a finger image with all its features in the form of a papillary pattern and transmits the result of scanning to the software. A specialized application compares the resulting image with the sample created during the biometric password generation phase.

Types of fingerprint scanners

All fingerprint scanners, which are currently used, can be classified into three groups based on the physical principle of operation:

- semiconductor (silicon);

- optical;

- ultrasonic.

Semiconductor scanners

This type of scanner gets an image based on the properties of semiconductors, which vary in the area of contact between the papillary pattern and the scanner. In the basis of this type of scanning devices can lie several technologies:

- Capacitive scanners. The work of such scanners is based on the effect when the capacitance of the pn junction in a semiconductor device changes when the crests of the papillary pattern and the elements of the semiconductor matrix are in contact.

- Sensitive to pressure scanners. A fingerprint scanner of this type uses a special matrix of piezoelements in its work. When the finger touches the matrix, the crests exert pressure on it, and the cavities, respectively, do not. Based on the pressure applied to the matrix, an image is formed.

- Thermo-scanners. Scanning devices of this type use sensors consisting of pyroelectric elements. These sensors fix the temperature difference, and then convert it into a voltage.

- Radio frequency scanners. Scanners of this type consist of micro-antennas that generate a weak signal, and the resulting image of the fingerprint is formed from the result of the electro-motive force in response to the papillary pattern.

- Stretch thermal scanners. The same as thermal scanners. The only difference is that the finger must be drawn along the scanning surface, and not attached.

- Capacitive broaching scanners. The technology of obtaining the image of the papillary pattern is the same as in the capacitive, but the method of production differs in that the finger is drawn along the scanning surface.

- Radio frequency scanners. The principle of operation of these devices is the same as in radio frequency devices, but the method of image removal is not the application of a finger to the device, but in carrying the finger along its surface.

Optical scanners

A fingerprint scanner of this type receives a finger image by the optical method. The operation of devices of this type is based on various technologies

- FTIR scanners. These devices use the effect of disturbed internal reflection.

- Fiber-optic scanners. The fingerprint reader is an optical fiber matrix, each fiber of which contains a photocell.

- Electro - optical scanners. The image is obtained from an electro-optical polymer, which in its composition has a light-emitting layer.

- Optical broaching scanners. This type of equipment is a refinement of optical devices in which you need to draw a finger across the surface to obtain an image, and not to apply it.

- Roller scanners. To obtain an image, you need to slide your finger along the roller, where fingerprints with papillary patterns are taken.

- Contactless scanners. The finger is scanned in a non-contact way. The finger is applied to the hole where it is illuminated by several sources, and the built-in camera captures the image of the finger.

Ultrasound scanners

This type of device scans the surface of the finger with ultrasonic waves, and based on the measured distance of the reflected waves from the valleys and protrusions, an image is constructed. This type of device differs from those discussed above in that the result of scanning is obtained more qualitatively.