AFM University Introduction to Atomic Force Microscopy by Paul West

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6.1 Probe Artifacts
6.1.1 Features on a Surface Appear Too Large
6.1.2 Features in an Image Appear Too Small
6.1.3 Strangely Shaped Objects
6.1.4 Repeating Strange Patterns in an Image
6.2 Scanner Artifacts
6.2.1 Probe / Sample Angle
6.2.2 X-Y Calibration / Linearity
6.2.3 Z Calibration / Linearity
6.2.4 Background Bow / Tilt
6.2.5 Z Edge Overshoot
6.2.6 Scanner Drift
6.2.7 X-Y Angle Measurements
6.2.8 Z Angle Measurements
6.3 Image Processing
6.3.1 Leveling
6.3.2 Low Pass Filter
6.3.3 Matrix Filter / Smoothing
6.3.4 Fourier Filtering
6.3.5 Image Looks Too Good
6.4 Vibrations
6.4.1 Floor Vibrations
6.4.2 Acoustic Vibrations
6.5 Other Sources
6.5.1 Surface Contamination
6.5.2 Electronics
6.5.3 Vacuum Leaks
6.5.4 PID Settings / Scan Rate
6.5.5 Laser Interference Patterns
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Chapter 6
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FIGURE 6-28 Example of an artifact created by not having the PID parameters optimized while scanning. In the upper image parameters are optimized, in the lower image parameter are not optimized and the error signal is large.
6.5.5 Laser Interference Patterns
Interference patterns can be created by the laser used in the LL-AFM sensor. The interferences appear as low frequency background oscillations in images and typically have a period that is similar to the wavelength of the laser light being used in the AFM scanner. The interferences can be created from patterns on the sample's surface, or from interferences in the cantilever. Figure 6-29 illustrates this type of artifact.
FIGURE 6-29 Wavy patterns (oscillations) in this image are an artifact created by laser diffraction with the sample's surface features. Scanning in a nonpatterned area gives images with no observable oscillations.

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