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DS 3408 Product Reference GuideGL-6
LASER - Light Amplification by
Stimulated Emission of Radiation
The laser is an intense light source. Light from a laser is all the same frequency,
unlike the output of an incandescent bulb. Laser light is typically coherent and
has a high energy density.
Laser Diode A gallium-arsenide semiconductor type of laser connected to a power source
to generate a laser beam. This laser type is a compact source of coherent light.
Laser Scanner An optical bar code reading device using a coherent laser light beam as its
source of illumination.
LED Indicator A semiconductor diode (LED - Light Emitting Diode) used as an indicator, often
in digital displays. The semiconductor uses applied voltage to produce light of
a certain frequency determined by the semiconductor's particular chemical
composition.
Matrix Symbols A 2-dimensional array of regular polygon shaped cells where the center-to-
center distance of adjacent elements is uniform. The arrangement of the cells
represents data and/or symbology functions. Matrix symbols may include
recognition patterns that do not follow the same rule as the other elements
within the symbol (i.e., Data Matrix and MaxiCode).
MIL 1 mil = 1 thousandth of an inch; a unit of measure often used to quantify bar
code printing and scanning dimensions.
Misread (Misdecode) A condition which occurs when the data output of a reader or interface
controller does not agree with the data encoded within a bar code symbol.
Module (1) The narrowest nominal width unit of measure in a symbol. In certain
symbologies, element widths are specified as multiples of 1 module.
Equivalent to X dimension; or (2) a single cell in a matrix symbology used to
encode 1 bit of data. In MaxiCode, the module shape is a regular hexagon. In
Data Matrix, the module shape is nominally square. In PDF417, the module
shape is a regular rectangle. In bar code symbologies, the module shape is a
regular rectangle.
Module Check Digit or Character A character within the symbol data field calculated using modular arithmetic
that is used for error detection. The calculated character is determined by
applying a code algorithm to the data field contents (see check character).
Moving Beam Bar Code Reader A device where scanning motion is achieved by mechanically moving the
optical geometry.
MRD Minimum reflectance difference: a formula that is used to determine if there
is an adequate difference between absorbed and reflected light.
Nanometer Unit of measure used to define the wavelength of light that is equal to 10
-9
meter.
Nominal The exact (or ideal) intended value for a specified parameter. Tolerances are
specified as positive and negative deviations from this value.
Nominal Size Standard size for a bar code symbol. Most UPC/EAN codes are used over a
range of magnifications (e.g., from 0.80 to 2.00 of nominal).
Non-Contact Reader/Scanner Bar code readers requiring no physical contact with the printed symbol.
Non-read The absence of data at the scanner output after an attempted scan, which is
due to no code, defective code, scanner failure or operator error.
Omnidirectional Bar codes read in any orientation relative to the scanner.
Optical Throw The distance from the scanner face to the closest point at which symbol can be
read; also, optical throw is the difference between range and depth of field.