Retrieve nano-features over millimeter ranges!
closed loop scanning & global sample coordinates
Science and technology delve deeper and deeper into the nanoworld. In
particular, scanning probe & confocal microscopy have been concerned with
features on the nanoscale ever since its invention. Reliably scanning over
tens of micrometers range down to a few hundred nm is comparatively easily
achieved by using piezo based scanners.
However, using piezo-based scanners usually relies on the assumption that
the relation between applied voltage and displacement is linear. In reality,
most scanners show large non-linear behaviour and hysteresis, especially
for large scan ranges. Creep, i.e. drift in position after approaching a certain
location, is a further phenomenon which is common to all piezo scanners.
In many experiments, reproducibly locating a small feature on a surface
is crucial, and sometimes hysteresis and non-linearity in the acquired
image are not acceptable. Sometimes, SPM images need to be evaluated for
particularly and for the specific mutual distances of certain features, and
hence, any distortions due to those nonlinearities may impede such analyses
significantly.
up to5 mm
Based on our patented FPSensor, a fiber-based interferometer, our micro-
scopes can now be equipped with position closed loop sensors with featuring
a steady-state resolution of down to 1 nm even in a, despite the cryogenic
working environment.
At the same time, we implemented a fully digital scan engine in the ASC500
SPM controller, which now features location based data acquisition (as
opposed to time-triggered data acquisition on open loop systems). In closed
loop mode, this results in perfectly linearized images. The sophisticated scan
engine even allows for an adjustment of the scan acceleration to smoothen
the scanning motion at the turning points, which can be is especially useful
especially for higher scan speeds.
The most useful new features however is that since the FPSensor covers the
full 5 mm x 5 mmm range of the positioners, the scan widget now contains
‘global’ sample coordinates: usually, the maximum range accessible in closed
loop mode is limited by the maximum range of the scanners. If the user wants
to scan outside of this area, he can simply use the global sample coordinate
system for navigation. To further facilitate this, any measured SPM images
can simply be decorated onto the scan widget’s sample ‘canvas’ via drag-
and-drop, where they are put exactly at the measured coordinates. Hence,
a virtual map of the whole sample gradually evolves within the scan widget.
Retrieving regions of interest on the nanoscale, which has always been
extremely difficult and time consuming especially at low temperatures, is
now an easy task thanks to this global sample coordinate system.
total available range
Much more often, however, finding a certain region of interest or a particular
feature on a macroscopic sample at all, or retrieving such locations repeata-
dly is a critical task.
CUSTOMER FEEDBACK
Prof. Dr. Peter Michler
Our attoCFM I LT-lithography setup is not only the best
choice when it comes to stability requirements. Its closed
loop scanning feature also allows us to optically pre-select
quantum dots suitable for desired experiments and mark
them in-situ via lithography with nanometric precision.*
(University of Stuttgart, Germany)
For more details, see
*[1] Sartison et al. Scientific Reports 7, 39916 (2017)