Measurement standard of length


The metre, symbol m, is the SI unit of length. It is defined by taking the fixed numerical value of the speed of light in vacuum c to be 299 792 458 when expressed in the unit m/s, where the second is defined in terms of ∆νCs.


In the Estonian national length measurement standard laboratory the scale is realised in the measurement range of 0.5 mm to 1000 mm by means of end gauges; in the area up to 120 m a laser interferometer is used. See the approved list of national measurement standards.


Otsmõõdud pikkusekomparaatoris UPC-100, millega on võimalik kalibreerida otsmõõte nimiväärtusega kuni 100mm.
End gauges in the length comparator UPC-100 allowing calibration of end gauges with a nominal value to 100 mm.

For offering a calibration service four end gauge sets and precision comparators UPC‑100 are UPC‑500 used. Length measurements are calibrated on a measurement bench by using Renishaw laser interferometer model ML‑10.

End gauges class K or 0 according to standard ISO 3650:1998(E) are calibrated in the following ranges:

  • 0.5 mm to 100 mm with expanded uncertainty (0.05 + 0.5×L) µm
  • 100 mm to 500 mm with expanded uncertainty (0.2 + 0.9×L) µm
  • 500 mm to 1000 mm with expanded uncertainty (0.2 + 2×L) µm

and length measurements in the range of

  • 1 mm…120 m with expanded uncertainty (0.06 +0.015×L) mm
Mõõtepink pikkusmõõtude kalibreerimiseks
A measurement bench for calibrating length measurements


Toomas Kübarsepp
Phone +372 524 0148