TMPM5200-2
5-65
s not so low.
If Loop Gain is set to a low number, the gain of the feedback circuit is so small
that the feedback voltage is not applied up to +150 V.
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Make sure that the RMS value displayed in RMS Value is not too close to the
value given in the Reference/V input box.
If the RMS value is close to that given in Reference/V, this indicates that the
approach has already been completed.
The following two reasons can be considered:
1. The amplitude of the cantilever vibration has become small.
If the cantilever tip is fairly close to the specimen surface, the cantilever am-
plitude could become small due to the attracting force of the specimen or the
electrostatic force acting between the specimen surface and the cantilever tip,
thus resulting in decreasing the RMS value close to the Reference/V value.
In such a case, change the Reference/V value to an even smaller value
(nearly 0 V), or repeat the adjustment.
2. The approach has already been completed, or the cantilever tip has collided
with the specimen.
Retract the cantilever tip from the specimen. Then, try to readjust it.
4.
Click on the Approach On button in the Tip window.
The motor for the approach starts to rotate and automatically stops when the RMS
value becomes the same as the value given in Reference/V. Confirm that the ap-
proach has been completed, using the indicator of the AFM AMP unit, the oscillo-
scope or the software oscilloscope.
•
When confirming the completion of an approach using the indicator of the AFM
AMP unit, check whether the RMS value is close to the Reference/V value (the
RMS value does not necessarily have to be exactly the same as the Reference/V
value).
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When confirming the completion of an approach using the oscilloscope or the
software oscilloscope, confirm that the Z voltage (CH1 or Channel A (red)) has
come closer to 0 V than the position it had when approach started. Also confirm,
using the software oscilloscope, that the RMS voltage (Channel B (blue)) ap-
proaches the Reference/V value.
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Topographical image observation
When approach has been completed, carry out the scan.
Starting scanning
Click on the Repeat button on the Advanced control panel. The scanning will
start and an image will appear in the Display Window.
In the AC mode, an important factor for obtaining a high-quality image is the
distance between the specimen surface and the cantilever tip. If this setting is
inappropriate, not only can a quality image not be obtained, but also the speci-
men and the cantilever may be damaged. You may set the distance between the
specimen and the cantilever tip using Reference/V. Generally, the scanning
speed for the AC mode is one step slower than that for the contact mode, even
for the same scanning range.
In such a case, check the following points:
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Make sure that Loop Gain i
