Biomedical Engineering Reference
In-Depth Information
Fig. 6.21. Example of the effect of sample drift on AFM images. The two images of a cluster of
E. coli
bacteria were measured with the slow scan axis in opposite directions. The difference
between them indicates that the sample was drifting while scanning. When the sample drifts in the
same direction as the slow scan axis, the sample will appear stretched (image on the left); if it drifts
in the opposite direction it will be compressed (right image). Scanning in two directions can help to
determine the cause of image distortion.
drifts in
Z
, this effect will eventually cause problems in scanning due to the limited
Z
scan
range of many scanners. If the user determines the sample is drifting, they should attempt
to fix the sample down more firmly, and remove possible sources of heat, for example the
white light used to illuminate the sample. Sometimes the only solution is to wait for
thermal equilibrium.
