What is the tetronom®?


TetronomThe tetronom® is a newly developed three-dimensional testing artefact that, when assembled, takes the shape of a tetrahedron. The concept of a tetrahedral testing device was developed within the Physikalisch Technische Bundesanstalt in Braunschweig (PTB) – German institution comparable to the National Association of Testing Authorities (NATA) or the American National Institute of Standards and Technology (NIST). Its design was further refined by metronom AG / Germany and converted into a commercial product suitable for the industry.


The tetronom® testing device is internationally protected by patents. It closes the gap between already available testing devices, and the requirements of metrology departments to comply with current quality standards. The tetronom® was developed in close consultation with users of mobile measurement systems as well as CMM operators worldwide.


The tetronom® consists of six bars forming a tetrahedron. Steel spheres at each corner hold the testing device together by magnetic forces. The tetrahedral form ensures a symmetrical, tension-free assembly. At each connection point, three bars meet. Combining materials with positive and negative expansion coefficients as well as using a composite, which is not affected by moisture, the tetronom® is subject to negligible low thermal expansions assuring the high accuracy necessary to verify measuring systems.


The tetronom® is available in bar lengths from 100 to 2,000 mm and in different precision classes. The distance between the centre points of the individual spheres is defined as the bar length and is calibrated by accredited measurement laboratories. Each tetronom® is supplied with a calibration certificate documenting the exact (nominal) lengths and measuring uncertainties of the individual bars. Thus the tetronom® meets the requirements of traceability to national and international length standards and can be used as a reference standard.




The tetronom® is suitable for the regular verification of following systems:

  • Coordinate measuring instruments (CMM)
  • Theodolite measurement systems
  • Precision tachymeters
  • Multi-axis measuring arms
  • Laser scanners
  • Laser trackerss
  • Laser radar
  • Tactile online photogrammetry
  • Optical online photogrammetry
  • Offline photogrammetry


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