HEIDENHAIN ND 1300 VED and Crosshair Systems - Manual (Page 283)

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11
Setup
Performing video parcentric and parfocal calibrations
Parcentric calibration eliminates X and Y axis measurement offset errors
that can occur when changing video magnifications. Parfocal calibra-
tion eliminates z-axis measurement offset errors that can occur when the
video focus is adjusted when changing magnifications.
NOTES
As shown in the essential setup requirement diagram
earlier in this chapter, camera skew calibration,
squareness calibration and error correction must be
performed prior to this process.
As shown in the diagram on the right, leveling, establishing a datum
and measuring a circle are required steps in this procedure. Refer to
Chapter 6: Measuring for details regarding these activities if neces-
sary.
Parcentric and parfocal calibrations are performed simultaneously using
a single circle artifact in the calibration process diagrammed at the right
and described below. To perform parcentric and parfocal calibrations:
1 Zero any existing Parcentric and Par-
focal X,Y and Z offsets by selecting each
magnification and entering zero values
into the Offset X, Offset Y, and Offset Z
data fields.
2 Select the high-
est video magnifica-
tion. In this example,
M1 happens to be the
highest magnifica-
tion. Your system
might be different.
Zero all offsets
Select the highest magnification
Magnifications Screen