DMTA-10055-01EN, Rev. A, February 2015
Chapter 11
246
Figure 11-16 DGS/AVG curves on screen
11.3.2 Curve Adjustment Options
Once a DGS/AVG curve has been calculated on the EPOCH 650, you can make
adjustments to that curve during an inspection. These adjustments include gain
adjustments allowing proper defect scanning and code-compliant defect sizing, as
well as reference-reflector adjustments.
11.3.3 Transfer Correction
Transfer correction is an adjustment in the reference gain setting during calibration of
the instrument. It is typically added when the surface conditions between a
calibration block and test piece are different. The coupling conditions on the test
surface can often cause signal loss after calibrating a DGS/AVG curve, which results in
inaccurate comparisons of the test reflectors with the calibrated DGS/AVG curve. The
EPOCH 650 allows you to adjust for this difference by adding transfer correction to
the calibrated base gain after completing the DGS/AVG curve setup.
The transfer correction can be added during initial setup of the DGS/AVG curve
(DeltaVt value), but typically this factor is unknown until after the setup is
completed.
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