Rockwell Automation 2755-L7, -L9 Scanners - Manual (Page 47)

Glossary
G–9
read
A successful scan of a bar code symbol.
reflectance
The amount of light returned from an illuminated surface.
reflectance, absolute
The ratio of the total reflectance by a document to the total light incident on
the document.
reflectance, diffuse
Reflected light whose angle of reflection varies from the angle of incidence
of the illuminating light; such as reflection from a non–glossy surface.
reflectance, specular
Reflected light whose angle of reflection is equal, or nearly equal, to the
angle of incidence of the illuminating light, as in reflection from a mirror.
reflex
A method of object detection in which the source and detector are located on
the same side; a retroreflector on the far side returns the energy from the
source to the detector.
resolution
1) The measure of the ability of a lens, a photographic material or a photographic
system to distinguish detail under certain specific conditions.
2) The dimension of the smallest element which can be printed employing a
particular technique.
3) The narrowest element dimension which can be distinguished by a particular
reading device.
retroreflective
Characteristic of material causing it to reflect light back to its source
regardless of angle of incidence.
retroreflector
A reflector, specially constructed, which reflects energy back to the source
from which it came. It is also known as a “corner reflector”.
reverse image
A symbol in which the normal dark areas are represented in the light areas.
S
scan
The search for a symbol or marks which are to be optically recognized.
scan head, scanner
A device that optically scans bar code symbols and converts the optical
information into digital or analog form and sends it to a decoder.