Modelling of precision line scale comparator

Abstract

The paper deals with errors of precision line scale comparator investigated by employing finite element mod-eling. Accuracy requirements for such systems are high therefore the influence of small deformations on geometri-cal dimension stability of the comparator caused actually by some hundredth parts of Kelvin or dynamic processes is important. A novel FE model enabled us to evaluate possi-ble displacements of the system due to seismic vibrations transmitted by the construction base and supports as well as ambient temperature changes that determine position and angular deviations between the microscope and the measured scale. The performed calculations have proved that the accuracy of the comparator is influenced by focus-ing errors of the optical line detection system and possible angular deviations of optical components therefore the weight of the factors inducing these errors must be mini-mized as well as compensation possibilities of these errors have to be investigated in the design of such systems.