Non-catastrophic failure of the laser transducer system in a universal measuring machine

Abstract

An unanticipated failure of the laser displacement transducer system used for the read-out of position in a universal coordinate measuring machine is reported. The failure was detected by the Primary Standards Laboratory (PSL) at Sandia National Laboratories and was verified by measuring a mechanical standard previously calibrated by the National Institute of Standards and Technology (NIST). The method involved a series of measurements using wavelength compensation numbers which varied from the nominal setting calculated using Edlen's formula by as much as ±5 ppm . The measurement values of the artefact obtained using a new circuit board in the system were compared to those obtained using the malfunctioning board. The failure was confined to a single circuit board in the laser system. A description of the faiure is given and the potential effects upon measurements using the universal measurement machine are assessed.