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Glossary-6
P 300 STD/FZY/PRO Scanner Product Reference Guide
LASER An acronym for 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 SPOT SIZE The diameter of the spot of laser light scanning the bar code,
as measured at a given distance from the bar code. Smaller
spot sizes yield higher resolution but poorer depth of focus.
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.
MIL 1 mil = 1 thousandth of an inch.
MINIMUM REFLECTANCE
DIFFERENCE (MRD)
The difference in percentage between light reflected from
spaces (R
S
) and light reflected from bars (R
B
). MRD = %R
S
- %R
B
.
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 The narrowest bar or space (unit of measure) in a code. The
term is used by the Uniform Code Council in its description
of UPC/EAN code; it is also used in the description of Code
128. Contiguous modules are used to form bars or spaces
which are wider than one unit.
MODULE ASPECT RATIO The ratio of height to width of the narrowest bar or space, or
unit of measure, in a bar code.
NANOMETRE A unit of measure used to define the wavelength of light.
Equal to 10
-9
metre.
NOMINAL The exact (or ideal) intended value for a specified parameter.
Tolerances are specified as positive and negative deviations
from this value.