Patent ID: 8336219
Filing Date: 2012-12-25
Classification: G01B

Abstract:
1. A method of calibrating a measurement scale in a scanning head using a reference artefact, the method comprising the steps of; (i) rotating a surface sensing device mounted on the scanning head about at least one axis of the scanning head to move the surface sensing device into a plurality of different angular orientations relative to the reference artefact, the scanning head comprising at least one scale that provides a measure of a rotational position of the scanning head about the at least one axis; (ii) measuring, with the surface sensing device, at least one property of the reference artefact at each of the different angular orientations of step (i); and (iii) creating an error map or function relating measurements of the at least one measurement scale to angular orientations of the scanning head using the properties of the reference artefact measured in step (ii).