Laser Scanner

A laser scanner reads codes using low-energy laser light. The light beam from the laser diode is directed through an aperture by means of a rotating polygon mirror and then strikes the barcode. The mirror consists of several segments. The rotary motion of the polygon mirror in combination with the reflection from the individual sections of the mirror assures that the laser beam is continuously deflected to a single plane, creating a migrating point of light which scans, for example, a barcode. The dark bars reflect less laser light than the light spaces. A portion of the reflected light re-enters the aperture and once again strikes the polygon mirror, which directs it to a photodiode via a mirror with drill-hole and a converging lens. The photodiode converts the intensity of reflected light into an electrical pulse train. The individual current pulses are measured and evaluated by the decoder and are then assigned to corresponding information characters (information character). Further data processing is generally accomplished with the help of a computer.