It uses a Laser beam as light source, which uses a mirror or rotating prism for scanning the Laser beam back and forth across the Barcode. Laser scanners can be purchased with different resolutions, to enable them to read Barcodes of different sizes. Scanner resolution is measured by size of dot and of light emitted by reader, the most commonly used X dimension is 13 mils ( roughly 4 printer dots on a 300 DPI printer )because X dimension is so small, it is extremely important that the Barcode is created with a program that creates high resolution graphics.
Uses an array of hundreds of tiny light sensors lined up in a row in the head of the reader, each individual light sensor is extremely small, the voltage pattern is identical to the pattern in a Barcode, which are generated in the reader by sequentially measuring the voltages across each sensor in the row.
It is the newest type of Barcode reader it uses a small video camera to capture an image of the Barcode. The reader use sophisticated digital image processing technology to decode the Barcode. Video cameras have got hundreds of sensor rows arranged in a two dimensional array so that they can generate an image.