Force Imaging
Force Calibration Control Panels and Menus
Rev. B
MultiMode SPM Instruction Manual
185
Number of Samples
This parameter de
fi
nes the number of data points captured during each extend and retract operation
of the Z piezo during
Force Calibration
. This parameter does not affect the number of samples
used in
Image Mode
.
Average Count (Advanced Mode Only)
This parameter de
fi
nes the number of
Force Calibration
scans taken to average in the display of
the
Force Calibration
graph. Set to
1
unless the user needs to reduce noise. Otherwise, set between
1
and
1024
. No curves are displayed until “Average Count” curves have been collected. Also, drift
may cause systemic error in the resulting plot.
11.3.2 Main Controls Panel (Display)
Spring Constant
The parameter de
fi
nes the spring constant of the cantilever. The spring constant will be saved with
captured force plots.
Display Mode
This parameter de
fi
nes the display as either the approach, the retract, or both.
Units
This item selects the units, either metric lengths or volts on the piezo, that de
fi
ne the parameters and
the axes of the graph. Changing this item in
Force Calibration
mode also changes it in the
Realtime
imaging mode.
X Rotate
X Rotate
allows you to move the tip in the X direction during ramping. This is useful because the
cantilever is at an angle relative to the surface.
X Rotate
prevents the cantilever from plowing the
surface laterally, typically along the X direction, while it indents in the sample surface (in the Z
direction). Plowing occurs when the cantilever bends during indentation or with X movement
caused by coupling of the Z and X axes of the piezo scanner.
X Rotate
moves the scanner in the
same direction in which the cantilever points. Without
X Rotate
control, the tip moves in the
direction of the cantilever during indentation. Normally, it is set to about
22.0 degrees
. This
parameter typically ranges between
12
and
25 degrees
.
