Barcode scanning methods

We currently use the following main technologies:

Laser sensors

These use a laser diode as a light source. The laser beam is then scattered in two directions across the barcode area by a reciprocating (oscillating) mirror or rotating prism. The reflection of the light is sensed by a photodiode tuned to the wavelength of the laser beam, which measures the intensity of the reflection and thus obtains information about the lines and gaps in the code. Laser readers are used to read only so-called linear codes due to the linear reading principle and some compound codes. Their main advantage is the simplicity of their design, the ease of targeting the code with a visible laser beam and reading over longer distances.

CCD sensors

A CCD sensor contains hundreds of miniature light sensors arranged in a row that measure the level of light reflected from the code. Readers often contain LEDs, both to illuminate the code and to focus it. The main advantage of these readers is the absence of mechanical parts susceptible to damage, e.g. by falling, and the higher reading speed. The disadvantage is the smaller reading distance. These readers are mainly suitable for reading linear barcodes.

Imagers

These sensors use a CCD chip, which we know from digital cameras and camcorders, for scanning. The code is photographed by the device and the decoding is handled by software processing of the captured image. The main advantage of imagers is the capture of 2D codes, the ability to decode multiple codes at once. The disadvantage is the small reading distance and dependence on the intensity of the light.

Omnidirectional barcode scanners

They contain in most cases multiple laser sensors placed in different directions to be able to capture a barcode however tilted or rotated. Examples of omnidirectional readers include those familiar from supermarket counters, where the counter contains a built-in omnidirectional reader covered with sapphire glass through which the clerk moves the goods. To achieve multiple reading angles, the beam in these readers is scattered by a rotating polygonal mirror.