Instruction manual

Magnetic Force (MFM) Imaging
Advanced Topics
Rev. B MultiMode SPM Instruction Manual 237
In LiftMode, the Interleave Drive Amplitude can often be set to a value larger than in the main
scan, thus giving optimal signal-to-noise. In some cases this is beneficial as long as the Drive
Amplitude is not increased to the extent that the tip strikes the surface on the low point of its swing.
The signatures of tip-sample contact are white and black spots in the image, or, in extreme cases,
noisy, high-contrast streaks across the whole image. It is usually safe to increase the Drive
Amplitude until the first signs of tip strike are noticed, then reduce the amplitude slightly.
• When using amplitude detection, variations in Drive Amplitude affect sensitivity and
image contrast as well as signal-to-noise ratio. This is because changes in the oscillation
amplitude change the slope of the amplitude vs. frequency curve, and hence the effective
sensitivity; see Figure 13.2d. With phase detection and frequency modulation, changes
in amplitude produce no change in contrast, and results are thus more reproducible than
with amplitude detection.
Note: On some microscope models, there is a lowpass filter in the scanning
electronics that prevents fast switching of the Drive Amplitude between main
and Interleave scanning. This can interfere with very fast rates (> a few Hz).
WARNING: Before enabling the Interleave Drive Amplitude, check
that its value is not much larger than the main Drive
Amplitude value to prevent possible damage to the tip.
AVERTISSEMENT: Lors d’un travail en mode intercalé (Interleave
Mode), vérifier que la valeur de tension
appliquée à l’oscillateur piézo-électrique est
inférieure à celle appliquée à l’oscillateur en
mode imagerie (Main Drive Amplitude). Le
non respect de cette procédure peut entraîner la
destruction de la pointe.
WARNUNG: Bevor Sie im Interleave-Mode die “Interleave Drive-
Amplitude“ einschalten, vergewissern Sie sich bitte, daß
der dort eingetragene Wert nicht wesentlich größer ist,
als der Wert der “Main Drive-Amplitude“, um evtl.
Beschädigungen der Spitze vorzubeugen.