Instruction manual

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 specifies 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 Figure 11.2a, this parameter defines 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 defines the maximum voltage applied to the Z electrodes of the piezo during force
calibration operation. The triangular waveform shown in Figure 11.2a displaces the piezo up and
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 defined 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 defines 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 defines the piezo speed to bring together the tip and sample.
Reverse Velocity (Advanced Mode Only)
This parameter defines the piezo speed to separate the tip and sample.
X Offset, Y Offset
These parameters define the X and Y positions where the force plot will be collected.