Workshop on uncertainty in length measurements

At the last EUROMET Length Contact Persons meeting in October 2000 in Oslo, it was proposed to organize a workshop on uncertainty in length measurements in conjunction with the next contact persons meeting. A short inquiry among the contact persons resulted in a positive reply.

The workshop will be held in an informative way. There will be presentations and discussions of general concepts and several practical cases of measurement uncertainty in dimensional metrology. The following topics have been proposed so far:

  • uncertainty in cylindiricity and squareness mesurements
  • uncertainty in surface roughness measurement for horizontal parameters (Sm, Rsm)
  • temperature gradient in air (laser measurements)
  • influence of flatness in angle and gauge block measurements
  • addendums to the GUM
  • uncertainty budgets for CMC top services: a comparison of different approaches
  • optical measurement and uncertainty of focal length of Koesters interferometer
  • uncertainty in form measurements
  • 2D uncertainty analysis for sphere diameter measurement (Mathematica application)

Several experts have already agreed to give a presentation. Further ideas are still welcome! The definitive programme and schedule will be fixed early September 2001.

Final Report 2001-10-17

The workshop took place after the annual EUROMET Length TC meeting, on 16./17.
October 2001 in Budapest. The following contributions were presented:

• Peter Harris, NPL, The planned supplemental guide to the GUM: Numerical Methods for Propagating Distributions
• Rob Bergmans, NMi/VSL, Uncertainty estimation by the concept of virtual instruments based on Monte Carlo methods (Straightness, roughness and CMM)
• Heikki Lehto, MIKES, Influence of temperature gradients in air for laser length measurements
• Zbigniew Ramotowsky, GUM, Optical measurement and uncertainty of focal length of Koesters interferometers
• Michael Neugebauer, PTB, Uncertainty in form measurements
• Gerard Kotte, NMi/VSL, 2D uncertainty analysis for sphere diameter measurement(Mathematica application)
• Andrew Lewis, NPL, Uncertainty for stylus surface texture measurements
• Sandro Balsamo, IMGC, About stadard deviations of laboratories in intercomparisons with multiple measurands
• Ruedi Thalmann, METAS, Uncertainty assessment for CMMs using calibrated workpieces (according to ISO/DTS 15530-3)

The presentations were surrounded from lively discussions. The workshop was highly appreciated by the participants and the wish for a similar event at the next TC meeting was expressed.

The papers are available on the EUROMET Length web site at