A device specialized for reading barcodes and converting them into digital data. Pen scanners, also known as wand scanners, were the first type of scanner developed in the 1970s. The tip of the pen must physically touch the barcode. Later, laser scanners allowed the code to be read at a distance from the head of the device, enabling supermarkets to read round cans and flexible packages more easily. The most common type today is the visible laser diode (VLD) scanner, which emits as many as 50 laser beams simultaneously to capture the image at any angle. See barcode, mobile tagging and point of sale.
Laser Diode Mechanism
A laser diode (1) emits a beam (red) onto a combination of rotating (2) and fixed mirrors (3) that shine multiple beams onto the barcode (4). Although as many as 50 beams may hit the package at different angles, only one is shown in this illustration. The reflected light (yellow) is captured by the collector (5) and aimed at a sensor (6).
The black bars absorb light, while the white bars reflect it. Photo diodes turn the reflected light into an electrical signal, which is converted into digital pulses.
Scanning a Package in Staples
Modern omnidirectional scanners make it easy to capture the code at all angles with less precision required on the part of the human operator.