A barcode scanner or a barcode reader is defined as an electronic device that reads printed barcodes. The main aim of the scanner is to read the data. This is done using many technologies. Each scanner using a different technology has a different design. The barcode scanners are classified into five main types based on the technology used. They are pen-type, laser, CCD, camera-based, and omni-directional scanners.

Pen-type Scanners:
Pen-type scanners have to be put in close contact with the barcode on an item. These are the most simplest scanners used. A light source and a photodiode are placed next to each other in the tip of a pen or a wand. The tip of the pen has to be moved across the barcode in a steady motion. The intensity of the reflected light from the light source is measured by the photodiode. Then a waveform is generated. This measures the widths of the bars and spaces in the barcode. Morelight gets absorbed by the dark bars and more light is reflected by the white spaces. Thus a varied waveform is obtained by varied voltage. The scanner then decodes the waveform.

Laser Scanners:
The working of the laser scanners are most similar to that of pen-type ones. However, they use a laser beam as a light source. A reciprocating mirror or a rotating prism is used for scanning the laser beam back and forth across the code. The reflected light measured by the photodiode is tuned to a particular frequency. These scanners are fast and accurate. Some models of these scanners have the capacity to read the code from greater distances. Decoders are also used by some of these scanners which directly translate the received information into text.

CCD Scanners:
An array of hundreds of tiny light sensors are lined up in a row in the head of CCD sensors. The sensors are placed in a row and the scanner takes a linear picture. These readers measure the emitted ambient light and thus a voltage pattern is obtained that is identical to the pattern in the barcode. Where as the laser and pen-type scanners measure the reflected light.

Camera-based Scanners:
A small video camera is used to capture an image of a barcode. The digital image is then decoded by some techniques and the barcode is decoded. Instead of light sources arranged in a single row, hundreds of light sources that are arranged in two-dimensional arrays are present. Hence these are termed as 2D imaging scanners.

Omni-directional Scanners:
These scanners use light source which emits light in many directions. Mostly a laser is used as a light source. These scanners have the ability to read barcodes that are placed at any angle. This is due to the pattern of beams that are used. Certain supermarkets use these type of scanners which can read the labels from a few inches. However, some industrial models read the codes from a few feet away also. Some labels which are wrinkled, damaged, and dirtied can also be read by these scanners.

Such different types of scanners are available through Symbol scanners, Hewlett scanners and so on.