NEW FRONTIERS IN ANGLE METROLOGY AT THE PTB

Ralf D. Geckeler, Michael Krause, Andreas Just, Oliver Kranz, Harald Bosse

Abstract

An overview of the current status of angle metrology at the Physikalisch-Technische Bundesanstalt (PTB), the National Metrology Institute of Germany, is provided. Current and future challenges to angle metrology are described. Novel developments at the PTB are outlined. Our research programme is currently strongly influenced by the European Metrology Research Programme (EMRP) SIB 58 Angle Metrology project. We present our novel selfcalibration method for the fast and precise in-situ calibration of angle encoders without recourse to external reference standards which relies on a suitable geometric arrangement of multiple heads which read out the radial grating of the encoder at different angular positions. Additional progress has been achieved in this field by adapting an advanced error-separating shearing technique to angle metrology and by testing it experimentally. This technique, by applying defined angle offsets between two angle measuring devices, offers a unique opportunity to cross-calibrate both devices. We also present progress in the development of a novel concept and of a device for the precise and traceable calibration of spatial angles, the Spatial Angle Autocollimator Calibrator (SAAC). We report on the status of the first European Association of National Metrology Institutes (EURAMET) Key Comparison on autocollimator calibration (EURAMET.L-K3.2009).

Keywords

angle measurement, angle standard, angle encoder, autocollimator, traceability

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IMEKO-TC14-2014-02.pdf

DOI

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IMEKO TC

TC14 - Measurement of Geometrical Quantities

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