AC Modes
5
Keysight 5500 SPM User’s Guide
5-7
Next, bring the tip into contact with the sample. In AAC mode,
“contact” occurs when the cantilever oscillation is dampened to a
specified percentage of the total oscillation.
15
In the Scan and Z Controls window, open the
Motor
tab
Figure 6-5
Set the Stop At value in the Motor tab
16
Set the Stop At (%) to specify the percentage of total oscillation that
represents “contact.” For example, if the total oscillation amplitude
(set in
) is 2 volts, and the Stop At value is set to
90 %
, the
approach will stop when the oscillation is damped to 1.8 volts.
17
Click the
Approach
button in the PicoView toolbar
. The
system will raise the sample until the amplitude is damped to the
Stop At percentage. Because of air damping, oscillation typically
decreases as the tip nears the sample. The software monitors the rate
of change of amplitude as well as the absolute value, so the final
amplitude will not be exactly the Stop At percentage.
18
In the Servo tab set the I Gain and P Gain to
5 %
. These gains dictate
how quickly the system will react to changes in amplitude.
19
In the Scan Controls section, enter a scan Speed of
1-2
ln/s and a
Points/Lines setting of
256
. More information on fine tuning these
20
In the Scan tab, enter the
Size
(in microns) and
X Offset
and/or
Y
Offset
values to set the size and center of the scan. You can also click