METHOD AND APPARATUS FOR INSPECTING WORKPIECES

摘要

A series of nominally identical production workpieces is measured on a measuring apparatus. To correct for temperature variations, one of the workpieces forms a master artefact, the dimensions of which are known, e.g. by external calibration. The master artefact is measured on the measuring apparatus at two or more temperatures, producing two or more corresponding sets of measured dimensional values of the master artefact at the respective temperatures. One or more error maps or look-up tables or functions are generated which relate the measured dimensional values of the master artefact to the known dimensions of the master artefact. The error map(s), look-up table(s) or function(s) are dependent on the respective temperatures at which the master artefact was measured. Correction values derived from the error map(s), look-up table(s) or function(s) are used to correct the measurements of production workpieces in the series. These correction values are determined in dependence upon the temperature at which the workpiece measurements were obtained.