Metrological Set-Up and Procedure for Calibration of Displacement Transducers

High-precision displacement transducers are widely used in dimensional metrology due to their sub-micron accuracy and broad applicability. The increasing use of such sensors has led to a growing demand for SI-traceable calibration, requiring high-accuracy systems beyond the capabilities of commercial solutions. This paper presents the development of a dedicated calibration system for displacement transducers with measuring ranges up to 150 mm and its experimental evaluation over a 60 mm measurement range. The system is based on commercially available components and employs a laser interferometer as the reference standard, enabling an absolute measurement principle with direct traceability to the primary length standard. The calibration set-up is fully automated and designed to minimize dominant sources of systematic errors, particularly geometric misalignments including transducer alignment, interferometer beam alignment and Abbe error. A structured calibration procedure and a comprehensive measurement uncertainty model are presented to ensure repeatable and traceable calibration. Experimental evaluation was performed using a high-resolution displacement transducer with 60 mm measurement range in both directions of motion. The results demonstrate the repeatability and performance of the developed system over the experimentally investigated 60 mm measurement range and are consistent with the proposed uncertainty model. Based on this model, the expanded measurement uncertainty of the proposed calibration system is estimated to be 130 nm (k = 2) for measurement ranges of up to 150 mm.