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5.4.
Astigmatism Correction
❖
When observe image at high-magnification (e.g. 3000X-10KX), the alignment of final aperture
is in well adjustment, but the user also can not acquire a clear image.
❖
Making the image to be over or under focus, if the
“characteristic point” on image is stretched
in two perpendicular directions, there must be astigmatism which needs to be corrected.
Note:
If the absolute value of stigmator is overlarge, it should be considered to do some work in
following aspects:
--The column is heavily polluted which needs to be cleaned.
--The final aperture is polluted which needs to be changed another aperture. Or the 3
apertures need to be cleaned or replaced 3 new apertures.
--The alignment of final aperture is bad, it is needs to readjust again.
Steps of astigmatism correction procedure:
1.
Select [Active Area], adjust magnification to 2000X-3000X. Use slow scanning speed mode.
2.
Clicking the [Stigmator] button
on panel can start stigmator adjustment. Dragging
horizontal and vertical scroll bar of [Stigmator] can control stigmator.
3.
Dragging leftward or rightward in X direction to make the image clearest.
4.
Dragging upward and downward in Y direction to make the image clearest.
5.
Increase the magnification to 3000X-5000X, repeat the step 3 and 4 as necessary.
Содержание A63.7069
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