Typical Image Artifacts
Rev. F
Scanning Probe Microscope Training Notebook
59
the top of the scan. The image on the right is an example of skips and streaking caused by loose
debris on the sample surface. Often, loose debris can be swept out of the image area after a few
scans, making it possible to acquire a relatively clean image. Skips can also be removed from a
captured image with the Erase Scan Lines function (see
).
Figure 20.0c
Contamination from Sample Surface
Interference between the incident and reflected light from the sample surface can produce a
sinusoidal pattern on the image with a period typically ranging between 1.5-2.5µm. This artifact is
most often seen in contact mode on highly reflective surfaces in force calibration plots and
occasionally in TappingMode images. This artifact can usually be reduced or eliminated by
adjusting the laser alignment so that more light reflects off the back of the cantilever and less light
reflects off the sample surface, or by using a cantilever with a more reflective coating (MESP,
TESPA) (see
).
Figure 20.0d
Optical Interference
When the feedback parameters are not adjusted properly, the tip will not trace down the back side
of the features in TappingMode. An example of this can be seen in the image on the left which as
scanned from left-to-right (trace) producing “tails” on the colloidal gold spheres. The image on the
right is the same area imaged with a lower setpoint voltage, increased gains, and slower scan rate
(see
).
