Page 41
© 2001-2015 attocube systems AG. Product and company names listed are trademarks or trade names of their respective
companies. Any rights not expressly granted herein are reserved. ATTENTION: Specifications and technical data are subject
to change without notice.
Check the ‘Autoapproach Details’ where the following parameters should be
entered:
Coarse Axis:
Axis 3
Coarse Dir.:
Forward
Coarse Device:
ANC150
Coarse Trig. Pol.:
High Active
Coarse Trig. Hold Time:
0 µs
The auto approach should last between a few minutes and half an hour,
depending on approach parameters and initial tip-sample distance. After the
auto approach is finished, the sample surface is within reach of the z
scanner.
The figure below shows how the auto-approach signal is typically reflected
in the photo-detected AC signal AFM Aosc (at an already quite small tip-
sample distance)
4. Finding a good setpoint:
During the measurement, the distance (force) between tip and sample will
be held constant by the P/I-feedback loop that tries to keep the oscillation
amplitude at a given setpoint by varying the voltage applied to the z
scanner. It will now be described how a reasonable setpoint for the feedback
loop can be found with help of a z-spectroscopy:
In order to perform a ‘z-spectroscopy’, choose on of the ‘spec’ windows and
enter with the following parameters/values:
