Current research and development at the Nummela standard baseline
Jokela, Jorma and Pasi Hakli
The 60-year-old Nummela Standard Baseline is a unique length standard in geodetic metrology. This was verified again in the latest remeasurement with the VVissll (white light) interference comparator in autumn 2005. In this presentation we briefly present the newest results with some analysis and advances in the traceability chain. Present-day utilization of the baseline is illustrated with brief descriptions of recent and topical research and development projects. As a National Standards Laboratory the Finnish Geodetic Institute is a participant in the Mutual Recognition Arrangement (MRA) by the CIPM. All the activities meet the requirements of the ISO/IEC 17025:2005 and ISO 9001 quality standards. Since the beginning of interference measurements in 1947, the length of the 864-m-long baseline has changed less than 0.6 mm, and standard uncertainty has been smaller than 0.1 ppm. This enables reliable calibrations of the most precise electronic distance measurement (EDM) instruments in field conditions and traceable scale transfers. New working premises, completed in year 2004, and sheltering constructions around the observation pillars have greatly improved working conditions at the baseline.
Event: XXIII International FIG Congress : Shaping the change
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