Abstract

A conoscopic holography sensor (CH) integrated in a machining centre was used to analyse how the scanning strategy affects distance measurements between planes and to the reconstruction of a digitised surface. Distance measurement tests were conducted on a stepped specimen whereas the surface reconstruction was studied on a cylindrical surface. Two different scanning strategies were compared. In the first, the height position of the sensor kept constant along the surface scanning so that all the points were located at different positions within the sensor depth of field (DOF). In the second strategy, the sensor was continuously adjusted describing a trajectory equidistant to the surface so that all the points were acquired at a same distance within the DOF. Both strategies were compared by the discrepancies between measurements taken by the CH sensor and those obtained by a touch probe. Some recommendations are provided for distance measurement and surface reconstruction.

Keywords

Conoscopic holography, Scanning strategy, Depth of field, DOF, Measuring and surface digitising, On-machine measurement