Rockwell Automation 2755 Cordless Hand-Held Scanner - Manual (Page 101)

G–4 Glossary
Publication 2755-6.3
L
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 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.
P
Parameter
A variable that can have different values assigned to it.
S
Scanner
An electronic device used to scan bar code symbols and produce a
digitized pattern that corresponds to the bars and spaces of the
symbol. Its three main components are:
•
light source (laser or photoelectric cell) - illuminates a bar code.
•
photodetector - registers the difference in reflected light (more
light reflected from spaces).
•
signal conditioning circuit - transforms optical detector output
into a digitized bar pattern.
Symbol
A scannable unit that encodes data within the conventions of a
certain symbology, usually including start/stop characters, quiet
zones, data characters, and check characters.