Patent ID: 7464579
Filing Date: 2008-12-16
Classification: G01B

Abstract:
1. A method of calibrating a thickness probe/gauge comprising: a) using a calibration block having a measurement face and a recess extending inwardly of the block from a face opposite the measurement face, wherein at least part of the surface of the recess is inclined relative to the measurement face in all directions from a central region on the inclined surface of the recess, and wherein the measurement face comprises a reference feature, the location of which corresponds to a known point on the inclined surface of the recess, b) defining a coordinate system in the plane of the measurement face of the calibration block and extending perpendicularly into the calibration block, the coordinate system having an origin at the reference feature, c) noting the actual position of inclined surface of the recess in the coordinate system, d) placing the thickness probe over the reference feature at an undetermined offset from the origin of the coordinate system and setting the nominal position of the thickness probe to zero, e) measuring the thickness of the calibration block at a plurality of recorded positions remote from the reference feature, f) plotting the measured thickness values in the coordinate system, g) constructing a measured inclined surface of the recess within the coordinate system from the plotted thickness value, and h) comparing the measured position of the inclined surface of the recess to the actual position of the surface of the recess and generating a value representing the offset of the thickness probe relative to the defined coordinate system.