Keysight 5500, User Manual, Page: 123 / 330

AC Modes
5
Keysight 5500 SPM User’s Guide 5-6
Figure 6-4 Auto Tune parameters tab
9
Set the Peak Amplitude, which is the desired amplitude of cantilever
oscillation at the resonant frequency. A setting of
4 volts is a typical
starting value.
10
Enter an Off Peak value to offset the oscillation frequency from the
cantilever’s resonance frequency. A typical starting value is
-0.120 kHz .
A negative Off Peak parameter is used to ensure good engagement of
the tip with the sample as a drive frequency below the resonant
frequency means the amplitude will slightly increase as the tip
approaches the sample.
11
Click the Auto Tune button.
The system will sweep several times through the range of frequencies
specified in the Auto Tune tab and will locate the resonant frequency of
the cantilever. The Drive (%) will be adjusted automatically to set the
amplitude at the resonant frequency to the value set in the Peak
Amplitude box. Finally, the AC drive frequency will be set to the
resonant frequency, plus or minus the value set in the Offset box.
Figure 6-2 shows the result of the Auto Tune process.
12
Focus the cantilever in the video window.
13
Rotate the video system focus knob very slightly towards you such
that the tip goes just out of focus (the focal plane is just below the tip
now).
14
Press the Close switch to raise the sample until the sample comes
into focus.