STRAIGHT-line – Straightness Measurement System

The STRAIGHT-line is a high-precision straightness measurement system manufactured by Kunz precision and is used at METAS for the calibration of straightness and squareness standards. The system is based on a vacuum-preloaded air bearing mounted on a granite beam and, thanks to its compact measurement design, meets the highest requirements for stability and accuracy. An electronic probe and an incremental length measuring system enable the precise measurement of straightness deviations over measuring lengths of up to 800 mm.

For measurements requiring the highest accuracy, reversal measurements are used. This error separation technique allows the guideway errors of the measurement system to be separated from the form deviations of the object under test, thereby ensuring traceable straightness measurements with the highest precision. In combination with an angle measuring table, granite angle standards can also be calibrated for squareness.

The STRAIGHT-line enables the calibration of straightedges, test columns, straightness standards and granite angle standards up to 700 mm in length. Depending on the measurement method, measurement uncertainties of down to 15 nm for straightness measurements and 0.16 arcseconds for squareness measurements can be achieved. The system is therefore one of METAS's high-precision measurement facilities for the calibration of geometrical form standards.