GE XLG3 - Manual (Page 105)

96 Chapter 7 Measuring Features and Defects GE Inspection Technologies XLG3 VideoProbe System
To Take a Stereo Measurement
1. Attach the stereo tip securely, and verify it.
See “Verifying Measurement Tips” on page 108.
2. Position the probe tip for maximum accuracy.
See “To Position the Probe Tip for a Stereo Measurement Image” on page 94.
3. Freeze the image.
4. Select the measurement type and tip.
Press . Select Measure > Stereo > measurement type > tip.
5. Place the cursors in the left half-screen, as described on the screen.
Measurement accuracy depends on all cursors being positioned accurately. For best
accuracy in cursor placement, press
to activate the zoom window for a close-up
view of the image around the active cursor.
To learn how to place cursors for specific measurement types, see “Types of Stereo
Measurement” on page 98.
As you move each cursor, the matching cursor in the right half-screen moves
accordingly.
6. Inspect each matching cursor as soon as it appears.
Generally, you get the best results by leaving the matching cursors exactly where the
system places them. However, under certain circumstances, such as when a
repeating pattern exists, you may need to help the system find the correct match.
For details, see
“About the Matching Cursors” on page 93.
7. (Optional) Reposition the left-side cursors and the measurement result. Reinspect the
matching cursors.
8. (Optional) Verify your measurement accuracy.
Move each left-side cursor a few pixels. If the matching cursors move identically, and if
the results change only a little, you have probably achieved accurate results. But if a
matching cursor’s movement is erratic, or if the results change significantly, your
results are unreliable. Capture a fresh image, following the guidelines under
“To
Position the Probe Tip for a Stereo Measurement Image” on page 94.
Note This step is especially useful if you have to use a low accuracy index (less
than 5) or low match strength (less than 3). For example, you might have to
use a low accuracy index if you are measuring a large object or if you have
limited access and cannot bring the tip close to the target. You might have to
use low match strength if the surface has few details.