Biomedical Engineering Reference
In-Depth Information
Error
Height
261 nm
0 nm
0
µ
m
5.7
µ
m
0
µ
m
5.7
µ
m0
µ
m
5.7
µ
m
311 nm
0 nm
0
µ
m
5.7
µ
m
0
µ
m
5.7
µ
m0
µ
m
5.7
µ
m
Fig. 6.18. Example of an artefact created by not having the feedback (PID) parameters fully
optimized while scanning. In the upper image parameters are optimized, in the lower image
parameter are not optimized and the error signal is large. This also leads to less accurate height
image, see the line profiles.
Fig. 6.19. The effect of surface contamination. Left: SEM image of a heavily contaminated
calibration grid sample. Right: the contamination causes streaking and prevents the probe from
properly following the surface topography in the AFM image.
the AFM scanner (typically 0.5-1.5 microns). This interference originates from laser light
spilling over the cantilever, or passing through it, reflecting from the sample surface, and
interfering with the light reflected directly from the cantilever. A similar effect can also be
seen in force-distance curves, where the interference appears as waviness in the baseline
of the force-distance curve, with the same period. This is illustrated along with a typical
image showing the artefact in Figure 6.20.
