FEI Scios 2, Руководство пользователя

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Operating Procedures : Stage Control
C O N F I D E N T I A L – FEI Limited Rights Data 5-30
Stage Control
Eucentric Position
Establishing the eucentric position is an important part of setting up a sample for observation or modification.
At the eucentric position, the stage tilt and the beam axes intersect. When the stage is tilted or rotated in any
direction, this point remains focused and almost does not shift. At the eucentric position, one can use various
system components in a safe and optimal way (e.g. GIS, EasyLift).
Eucentric position should be adjusted after loading any new sample, as the sample loading clears all position
information.
Note

For electron imaging of non-tilted sample the eucentric position adjustment is not necessary. But it is still required to run
the Link Z to FWD procedure.
FIGURE 5-12
Eucentric Position Principle
Sample Top Surface Positioning
The distance between the observed sample and the stage rotation head surfaces must be properly set to bring the
stage to the eucentric position. This procedure also prevents the specimen to touch the final lens when moving the
stage in the Z-axis direction.
With the standard specimen holder it is possible to move the sample (its top surface) along the Z-axis up / down if
required (holder movement). This allows a flexibility to load large height specimens onto the stage.
1. Load a specimen onto the specimen holder.
2. Adjust the Z so that the highest specimen point is approximately 7 mm below the lens by using the optical
display.
3. Close the chamber and pump it down.
4. Switch on the beam, focus the specimen top surface and run the Link Z to FWD function.
The FWD is now recognised by the system as the
Stage module Z value.
4) Tilting the stage does not move the point of interest
out of the beam.
1) The point of interest is focused below the Eucentric
point.
Eucentric position
Tilt
Eucentric position
Z adjustment
Stage
Stage
2) Tilting the stage moves the point of interest out of
the beam.
Stage
Beam Beam
Beam
Point of interest
Point of interest
Eucentric position

and Point of interest
Feature is at
eucentric position.
Stage
Beam
3) The point of interest is focused at the Eucentric
point.