Operating Procedures: Stage Control
5-28
User Manual
C O N F I D E N T I A L –
limited rights
Feb 2018
Revision A
Stage Z module
This module enables slowly moving of the stage in the Z-axis
direction. The more the slider is pushed to the each side, the
faster the stage motion is. Clicking on the slider bar moves the
stage by a small step.
Tilt Correction module
When the appropriate check box is ticked, the function becomes
active.
•
Dynamic Focus
check box ticked – the focus automatically
changes as the beam scans from the image top to its bottom,
trying to follow the change in the working distance of the tilted
specimen.
•
Tilt Correction
check box ticked – the flat specimen
foreshortening compensation is on (in one direction, at a
known tilt angle, when the tilt axis is parallel to the stage XY
plane).
Because the image is a two-dimensional representation of a three-dimensional object, certain distortions occur.
For instance, a square grid image appears rectangular when you tilt the specimen. This function corrects the
aspect ratio and restores the square appearance.
•
Tilt Angle
list box – enables choosing among 3 modes.
In the
Automatic
mode, the
Tilt Angle
is equal to the stage tilt plus the
Specimen Pre-tilt
adjuster value (a Tilt
Angle correction in case the specimen is not parallel to the stage XY plane).
In the
Automatic
mode, 90° is added to enable observing the cross section perpendicular to the sample surface.
When in the
Manual
mode, the adjuster enables manually setting of the Tilt Angle from -90° to +90°. It is useful
when the Dynamic Focus with Automatic Tilt Angle does not give satisfactory results (or cannot be used at all
because the specimen is tilted in a direction different from that of the stage Tilt).
When switching from Automatic to Manual mode, the actual Tilt Angle is not changed. When switching to
Automatic mode, the Tilt Angle is set to the actual stage tilt.
Note
Both Dynamic Focus and Tilt Correction work properly only if the specimen (scanned area) is tilted around the X-axis (in
the same direction as the stage Tilt). Therefore they cannot be used with Automatic Tilt Angle in combination with a non-
zero Scan Rotation. If the specimen is tilted in a different direction, you have to align the tilt axis horizontally using the Scan
Rotation, and then optimize the image focus by tuning the Manual Tilt Angle.
Both functions are also disabled (check box cleared) in the Crossover mode.
Due to the limited range of dynamic focusing, the overall conditions should be within certain limits. If the dynamic focus is
out of range, an information sign next to the check box becomes visible. Leaving the mouse over this sign calls up a tooltip
giving advice with information about what must be done to enable it again (usually increase the dwell time or the
resolution).
