2. The paper is placed on the glass plate in the scanner and the lid closed over the top. A lamp is used to illuminate the scanned document (eg Cold Cathode Fluorescent Lamp (CCFL) or a Xenon lamp.) The mirrors, lens, filter and CCD make up the scan head. The scan head moves slowly across the paper using a belt that is attached to a stepper motor. The scan head is attached to a stabiliser bar that steadies the scan head and keeps it in place. Stabiliser bar A mirror reflects the document image using two or three mirrors to focus onto a lens. The lens focuses the image through a filter onto a CCD. Charged Couple Device (CCD) Source: http://computer.howstuffworks.com/scanner2.htm

3. The device basically converts the light energy provided in photons into electrical energy charge. It is this idea that as a photon strikes the surface of silicon, it dislodges an electron that creates an electronic charge. Source: http://micro.magnet.fsu.edu/primer/java/digitalimaging/ccd/virtual2/index.html

4. A finger is placed on the scanner An algorithm recognises a pattern in the fingerprint by interpreting it and storing the recognised arrangement. The scanner reads the fingerprint

5. This is an example of the electrical circuitry that detects ridges and valleys in your fingerprint. Source: http://computer.howstuffworks.com/fingerprint-scanner3.htm

6. A diagram of the retina Source: http://computer.howstuffworks.com/fingerprint-scanner3.htm A low energy infrared light source is trained on the retina. Photoelectric detectors convert the reflected light into electrical signals Blood cells surrounding the retina absorb light much more than the retina itself. The electrical pattern is stored in a database so it can be reused to identify a person.

7. Source: http://computer.howstuffworks.com/fingerprint-scanner3.htm The Iris Scanner Not to be confused with another, less prevalent, ocular-based technology, retina scanning, iris recognition uses camera technology, with subtle infrared illumination reducing specular reflection from the convex cornea, to create images of the detail-rich, intricate structures of the iris. Converted into digital templates, these images provide mathematical representations of the iris that yield unambiguous positive identification of an individual. Iris scanner being used

8. An overview of how an iris scanner works.