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5. Troubleshooting – What Can Go Wrong When
Measuring Images
Although the operation of the LS-AFM is quite simple, some problems can occur while imag-
ing samples. The following sections detail some of the most common problems that may
occur. It is important to keep these potential problems in mind when operating the LS-AFM.
5.1 Saturation of the Photo-Detector
Highly-reflective cantilevers can sometimes
pass too much laser light to the photo-detec-
tor. When this occurs, the light lever force
sensor will not work properly. When there is
too much light, the "Top + Bottom" signal in
the "Laser Align" window displays a value
greater than 3. This problem can often be
solved by flipping the gain switch on the
photo-detector down to low gain (see sec-
tion 4.4 for the location of the gain switch).
5.2 Sample Not Mounted Correctly
It is essential that the sample is rigidly
mounted on either a glass slide or petri dish.
If the sample is not mounted rigidly, it can
be difficult to get into feedback, and images
appear to have excessive vibrations.
5.3 Probe Not Seated Correctly
If the probe is seated correctly, it will be in
essentially the same place before and after
the probe is removed from the AFM. If it is
too difficult to align the light lever after a
probe exchange, examine the probe holder
closely to make sure that the probe is seated
correctly. Improper probe alignment may
cause resonance saturation.
V 1.1 / LS-AFM Users Guide
Section 5-1
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