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7.
GLOSSARY
The following terms may have additional meanings. The definitions that follow are in the context
of the MVR video metrology systems.
Accuracy
The maximum error that the system will produce when measuring a true
standard.
All-in-one PC
A space saving personal computer where all electronics, disk drives and
I/O connections are in the same enclosure as the video monitor, which is
an LCD color touch-screen. A keyboard and mouse are also included.
Axis
A direction which allows movement and along which dimensions can be
measured. In the MVR systems, the X-axis is horizontal from left to right,
and the Y-axis is from front to back, and the Z-axis is from bottom to top.
Blooming
A condition where the parts of the video image are distorted by oversatu-
rated bright regions, making illuminated regions appear larger than they
really are.
CCD
Charge Coupled Device. The solid-state image sensing element of the
video camera.
Distortion
Optical image distortion at the CCD sensor across the maximum field of
view. Expressed in percent for the dimensional error along one axis divided
by the true dimension.
DXF
A computer aided design (CAD) data file format developed by Autodesk,
Inc. and now also used by other companies for the export and import of
CAD data.
Focus
The condition which provides the sharpest image. Achieved by optimizing
the distance between the object and imaging optics.
FOV
Field of View. The region of the metrology stage being viewed by the camera
and displayed on the video monitor.
FOV Measurement
A video measurement performed in a single field of view without moving
the stage or camera.
Illumination, Front
Lighting applied to the object from the same side as the camera so that
surface features can be viewed on the video monitor.
Illumination, Back
Lighting applied from the back of the object so as to create a silhouette
when the object is viewed by the camera.
Mag
Shorthand for magnification.
Magnification, Lens
In a vision metrology system, the image size in the CCD plane divided by
the corresponding object size (0.30X to 4X for MVR telecentric lenses,
0.70X to 4.50X for 6.5:1 MVR zoom optics).
Magnification, Image
Magnification on monitor. Image size on the video monitor divided by the
corresponding object size. Same as lens magnification in a properly
adjusted optical comparator.
Parcentricity
The condition where a feature remain at the optical center of the video
image throughout the magnification range of zoom optics.
Parfocality
The condition where the video image remains in focus as the magnification
is adjusted from highest to lowest with zoom optics.
Pixel
A picture element. Term used to describe the individual light detectors of the
CCD sensor in the camera and also the individual light emitters of an LCD video
monitor.