© ICSPI Corp. 2007-2021
nGauge AFM User Manual 2.0
70
Four points and associated heights
Subtract the height of the valley from the height of the peak to obtain the height.
9.1.2.3.
Height Distribution
Another method of finding the height differences between the plateaus and valleys of the
calibration gratings is to use the distribution of height throughout the scan. This can be achieved
with the 1D Statistical Functions button.
Clicking this will create a preview of the height density of the scan. For a calibration grating, it
will be a distribution with likely two peaks. This is a density function of the heights. One peak will
be found at the h
eight of the ‘plateaus’ of the calibration grating, and one peak will be found at
the height of the ‘valleys’. If 3-point leveling was applied, the valleys should be found around 0.
Click apply if the preview graph appears acceptable for your purposes.
U
se the same ‘Measure Distances in Graphs’
tool as in the ‘Find Peaks’ method to find the
exact heights that are the most common in the scan (those that have the highest rate of
occurrence). Select the peaks and subtract the valley height from the plateau height to find the
measured height of the grating.
In our example, the peaks are located at -1.6 nm and 139.8 nm. Subtracting these gives 141.4
nm as the measured height.
