Sample Positioning for Micro-Computed Tomography

Ultra-Precision Air Bearing Rotation Stage

BAM, the German Federal Institute for Materials Research and Testing ("Bundesanstalt für Materialforschung und ‑prüfung"), operates a hard X-ray beamline at the Berlin electron storage ring BESSY II ("Berliner Elektronen-Speicherring Gesellschaft für Synchrotronstrahlung") together with the German national institute for metrology, PTB ("Physikalisch-Technische Bundesanstalt"). The BAMline is intended for X-ray fluorescence analysis, micro-computed tomography, X-ray topography, detector calibration and reflectometry.

Projections for X-ray computed tomography are taken from different angles over 180° to collect all data for the reconstruction, while synchrotron radiaton micro-CT requires extremely high precision to ensure that the recorded information always relates to the same volume element. Therefore, the requests for a sample rotation stage were high:

  • Highest guiding accuracy
  • Flatness and eccentricity < ±100 nm
  • Wobble < 2 μrad
  • Load capacity 20 kg

PI selected an ultra-precision air-bearing rotation stage to answer these demands. Qualification in-house was executed with capacitive sensors.