Dynamic error reduction of a nanometre-accurate Abbe-compliant position measurement system

Ultra-precision machine tools can be brought to higher accuracies by fully exploiting precision engineering design principles. For that reason, a linear encoder-based measurement system called 'moving-scale' has been developed, compliant with the Abbe-principle and allowing functional separation of the metrology and structural loop. Previous work showed that the thermo-mechanical stability of a 1-DOF system with a measurement length of 120 mm was 18 nm for temperature changes of ±0.5 °C. This paper describes the characterisation of the dynamic errors occurring during measurement of the position of a moving target surface. The largest error sources have been identified and reduced and were experimentally verified in a dedicated setup where the moving-scale position measurement was compared to that of a stable reference. The measurement uncertainty related to these dynamic errors has been shown to be 5 nm, which brings the total measurement uncertainty of the 1-DOF moving-scale measurement system to 21 nm.