Force Imaging
Force Calibration Control Panels and Menus
184
MultiMode SPM Instruction Manual
Rev. B
11.3.1 Main Controls (Ramp Controls)
Ramp Channel (Advanced Only)
This parameter speci
fi
es the channel you will ramp. To collect force plots, this parameter should be
set to
Z
. For IV curves,
Bias
is typically selected.
Ramp Size
As shown in
fi
nes the amplitude of the triangular waveform applied
to the Z piezo. The units of this item are volts or nanometers, depending on the setting of the
Units
parameter. Regardless of the size of the scan, the entire scan is shown in the force curve; therefore,
increasing the value of this parameter increases the horizontal axis scale on the force plot.
Z Scan Start
This parameter de
fi
nes the maximum voltage applied to the Z electrodes of the piezo during force
calibration operation. The triangular waveform shown in
down in relation to the value of
Z scan start
. Increasing the value of the
Z scan start
parameter
moves the cantilever closer to the sample by extending the piezo tube. The units of this item are
volts or nanometers, depending on the setting of the
Units
parameter. The initial value of
Z scan
start
is equal to the average Z-center voltage de
fi
ned by the feedback just prior to entering the
Force Calibration
mode. Decreasing the value of this parameter shifts the force curve on the
display to the left, while increasing the parameter shifts the curve to the right.
Scan Rate
This parameter de
fi
nes the rate that force plots are collected (typically ~1Hz). The ramp size,
forward velocity and reverse velocity determine the scan rate.
Forward Velocity (Advanced Mode Only)
This parameter de
fi
nes the piezo speed to bring together the tip and sample.
Reverse Velocity (Advanced Mode Only)
This parameter de
fi
nes the piezo speed to separate the tip and sample.
X Offset, Y Offset
These parameters de
fi
ne the X and Y positions where the force plot will be collected.