| Metrology area, Sub-field | Length, Dimensional Metrology |
| Description | Flatness of surface plates |
| Time of measurements | 2020 - 2021 |
| Status | Measurements completed |
| References | |
| Measurand | Flatness deviation |
| Transfer device | Optical flat with a diameter of 330 mm made of Zerodur |
| Comparison type | Supplementary Comparison |
| Consultative Committee | CCL (Consultative Committee for Length ) |
| Conducted by | EURAMET (European Association of National Metrology Institutes) |
| RMO Internal Identifier | EURAMET 1490 |
| Comments | This is a comparison of flatness measurements of an optical flat on an aperture of 300 mm diameter. The participants have to measure the inner part of 300 mm with optical instruments to avoid possible scratches on the surface when measuring with tactile instruments. The achievable measurement uncertainty of the flatness measurements should be less than 15 nm (k=2). |
| Pilot institute |
PTB
Physikalisch-Technische Bundesanstalt Germany |
| Contact person | Gerd EHRET |
| Pilot laboratory | |
|---|---|
| PTB |
Physikalisch-Technische Bundesanstalt, Germany, EURAMET |
| NIM |
National Institute of Metrology, China, APMP |
| NMIJ AIST |
National Metrology Institute of Japan, Japan, APMP |
| VNIIMS (now RCAM-Rostest) |
Russian Scientific Research Institute for Metrological Service, Rosstandart (now Research Center for Applied Metrology - Rostest), Russian Federation, COOMET |
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