AFM University Introduction to Atomic Force Microscopy by Paul West

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« Chapter 1
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 « Chapter 5
 
5.1 Process
5.1.1 Leveling
5.1.2 Histogram Adjust
5.1.3 Filtering
5.1.4 Scale / Zoom / Rotation
5.1.5 Error Correction
5.2 Display
5.2.1 2-D / 3-D
5.2.2 Pallets
5.2.3 Light Shading
5.2.4 Contrast / Brightness
5.3 Analysis
5.3.1 Line Profile
5.3.2 Line / Area Roughness
5.3.3 Height Analysis
5.3.4 Particle Analysis
5.3.5 Grains Analysis
5.3.6 Technical Samples
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« Appendix D
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Chapter5
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5.1 Process
5.1.1 Leveling
AFM images always have some background slope or curvature that must be removed from the image. Sources of the background can be an offset angle between the probe and surface, or curvature introduced into the image from the xyz scanner. There are several algorithms that are used for "leveling" the images. The primary methods are:
Line: Line by line leveling is the most common method for leveling AFM images. In this method each horizontal, or vertical, line in an image is fit to a polynomial equation, and then the polynomial shape is subtracted from image line. Then, the average height of each line is set equal to the previous line (see Figure 5-1).
FIGURE 5-1 Line by line leveling is the simplest method for removing unwanted background bow and tilt from AFM images. A line is "fit" to each of the scan lines, and then the "fit" line is subtracted from the scan line.
Three point: In the three point method, the AFM operator identifies 3 points on an image. The three points define a plane which is then subtracted from an image. Three point leveling is ideal for samples that have terraces where the background bow associated with the scanner is much less than the height of the terraces.

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