Int. J. Metrol. Qual. Eng.
Volume 3, Number 2, 2012
|Page(s)||89 - 95|
|Published online||14 November 2012|
ASME B89.4.19 standard for laser tracker verification – experiences and optimisations
National Physical Laboratory (NPL),
Hampton Road, TW11
Accepted: 14 June 2012
Laser trackers are becoming the tool of choice for large volume dimensional metrology applications such as the measurement of aerospace assemblies, power plant structures, civil engineering structures and terrestrial transportation vehicles. A laser tracker is a portable coordinate measuring system that tracks a moving target reflector and measures the position of the target in spherical coordinates (r, θ, φ). The metrological performance of a laser tracker is influenced by many factors including: compensation for atmospheric effects, thermal expansion of the instrument and its mount, thermal distortion of the workpiece or artefact being measured, the wavelength of the laser radiation, the internal alignment of the gimbal axes and the linearity and alignment of the internal angular measuring scales. The most important of these potential error sources, which fundamentally limit the achievable uncertainty, are the internal mechanical and optical alignments and the quality and alignment of the angular scales. Several national and international standards exist or are in the process of being developed for performance verification of laser trackers. ASME B89.4.19-2006 is one of the established standards used to verify the performance of laser trackers. The main test relies on measuring a known reference length in a variety of configurations and ranges and comparison of the observed error (laser tracker measured length minus reference length) with the specified maximum permissible error (MPE) defined by the manufacturer. The establishment of an ASME B89.4.19 laser tracker verification facility at NPL is introduced. We highlight the importance of tracker verification and discuss the error sources, which contribute to the tracker measurement uncertainty. Some initial results obtained using this new facility are presented.
Key words: Large volume dimensional metrology / laser trackers / ASME B89.4.19-2006 / performance verification / uncertainty / spherical coordinate measurement systems / portable measurement systems
© EDP Sciences 2012
Current usage metrics show cumulative count of Article Views (full-text article views including HTML views, PDF and ePub downloads, according to the available data) and Abstracts Views on Vision4Press platform.
Data correspond to usage on the plateform after 2015. The current usage metrics is available 48-96 hours after online publication and is updated daily on week days.
Initial download of the metrics may take a while.