PAGE 7
Hard- and Software Features
ASC500 SPM controller and Daisy software interface
Closed loop scanning & global sample coordinates
Based on our patented FPSensor, a fiber-based interferometer, our
microscopes can now be equipped with position sensors featuring a
steady-state resolution of down to 1 nm even in cryogenic working en-
vironment. 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 is especially useful for higher scan speeds.
The most useful new feature 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. With
our ultra-large range ANSx150 scanners, this is a massive 125 μm at cryo-
genic temperatures. Now, 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 re-
gions of interest on the nanoscale, which has always been extremely dif-
ficult and time consuming especially at low temperatures, is now an easy
task thanks to this global sample coordinate system.
Z Controller
The z scanner output is controlled by a digital PI algorithm with a band-
width of 50 kHz. The z output DAC has a resolution of 18 bit, yielding a
4 pm resolution on a 1 µm scan range.
• highly versatile; all signal channels can be used as control inputs
• physical units of PI gain
• setpoint modulation for PI fine tuning
• inversion of feedback gain
• inversion of output polarity
attoCONTROL
Electronic & Software Control Units