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© 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.
I.1.
System Overview
The attoAFM I microscope is a tool to image, characterize, analyze, and
manipulate materials surfaces on a nanometer scale in low temperatures
as well as high magnetic fields. This short chapter wants to give a rough
overview on the concepts of the system.
The attoAFM I consists of the
measurement head
which is inside a housing
suspended on the lower end of the
microscope stick
, which itself is placed
in a
vacuum tube.
Before cooling down the system, this vacuum tube is
evacuated and backfilled with some He exchange gas for coupling to the
temperature outside of the vacuum tube. Typically, this vacuum tube is
then cooled by insertion into a
He
bath cryostat
, a
Variable Temperature
Insert (VTI)
, a
pulse tube cooler
, or by other means.
The main part of the attoAFM I measurement head is the AFM
cantilever
, a
thin bar typically made from silicon and possibly functionalized with
different coatings, which is placed before the end of an
optical fiber
,
hence forming an optical cavity, the length of which can be measured by
a
laser/detector system
.
The sample to be examined is placed (in standard setups) on an
ANPxyz101
positioner stack for coarse motion (5 x 5 x 5 mm³) and an
ANSxyz100
scanner (typ. 30 x 30 x 15 µm³ at 4 K, for details see the
specifications page at the end of the manual). Just underneath there is
typically also a temperature sensor and a small heater, which allows
controlling the temperature of the sample precisely.
When the sample is brought into contact with the cantilever, the
interaction forces can be measured by recording the length of the cavity.
While the sample is scanned, typically the distance between -tip and
sample is kept constant by the use of a
feedback loop
. For these purposes,
one uses the
electronic scan controller
ASC500, which generates all
required voltages and records all relevant signals. Additionally, a
high
voltage amplifier ANC300
is part of the system, amplifying the unipolar,
0 – 10 V signals to 0 – 150 V, as well as generating the signals required to
move the stepper positioners.
Regarding the optics,
laser
light is guided to the fiber-cantilever cavity,
and the back-reflection is then detected by a
photo-receiver
. The signal
generated by the photo-receiver is analyzed and recorded with the
ASC500 controller.
