Oxford Instruments Cypher SPM, Руководство пользователя

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Cypher SPM
User Guide
Determining Image Quality:
l
Start the learning process on a sample with a known topography, like the Asylum Research Cal-
ibration Grating being used in this tutorial.
l
Look at the 'Scope Trace' below the image. This graph represents the most recent line of the
image. Blue indicates the tip moving left to right (a.k.a trace) and Red indicates tip returning from
right to left (a.k.a retrace ).
On most samples with relatively slowly changing features, trace and retrace should look the same.
In other words, the landscape should look the same if you are flying the exact same route one way
or the reverse. The image above shows the two as being quite different; this is an indication that
imaging parameters need to be adjusted.
4.
Nomenclature In the previous image the tip is not following the surface. As the blue trace shows
(left to right), the tip seems to climb up out of the pits of the calibration grating
quite nicely (the left edge of each pit is quite sharp) but then it descends back into
the next pit along a relatively gentle slope. During this descent the tip actually “flies
through the air” while it is completely un-deflected, a bit like a hang glider running
off a cliff. The lateral motion of the tip simply marches on as dictated by the XY scan
pattern. The feedback control algorithm is simply not aggressive enough to bring
the tip back down to the bottom of the pit. Such behavior is commonly called para-
chuting or poor tracking.
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