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.
REALISATION OF THE SCALE
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.
DEVICES AND POSSIBILITIES
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
Phone +372 524 0148