Abstract: A calibration method for a shape measurement with a variable distance between the scanning probe datum point and the measuring point on the surface of a workpiece, is provided. Based on the measured distance between the scanning probe datum point and each of a plurality of measuring points on the surface of a calibration object, and on the position of a reference point on a motion system platform on which the scanning probe assembly is mounted, corresponding to the scanning probe being in a sensing position of each of the plurality of measuring points, the method provides the necessary data for calculating the coordinate of a measuring point of the workpiece from the measured distance between the scanning probe datum point and the measuring point, and from the position of the reference point corresponding to the to the scanning probe being in a sensing position of the measuring point.

Abstract: An improved method for measuring the shape of a workpiece, and an associated device. The invention has three aspects. The first aspect of the invention is a triangulation device that creates an annular image whose diameter is a linear function of the distance from the device to the workpiece. According to the second aspect of the invention, the shape of a concave or reentrant workpiece is measured by folding the path of the incident light using a reflector inserted into the workpiece, so that light is reflected from the otherwise inaccessible interior walls of the workpiece. According to the third aspect of the invention, the incident beam of light is provided with a structured cross section.