Patent ID: 7660688
Filing Date: 2010-02-09
Classification: G01B

Abstract:
1. A surface-profile measuring instrument, comprising: a scanning probe including a probe to be moved toward or contacted with a workpiece surface with an arc portion on at least a part thereof, the scanning probe scanning the workpiece surface while keeping the relative position between the probe and the workpiece surface at a predetermined reference position; a scanning vector commanding unit that commands a scanning vector command indicating a next movement position of the scanning probe along the workpiece surface; a drive mechanism having a drive shaft that holds and three-dimensionally moves the scanning probe in accordance with the scanning vector command; a drive sensor that detects a drive amount of the drive mechanism; and a correction calculating unit that calculates a detection value of the drive sensor in accordance with the scanning vector command commanded by the scanning vector commanding unit, wherein the correction calculating unit calculates a correction-amount for correcting a measurement error generated by a deformation of the drive mechanism in accordance with the movement thereof; wherein the correction calculating unit includes: a correction-parameter storage that stores a correction parameter representing a relationship between acceleration caused on the scanning probe and the deformation of the drive mechanism; a correction-amount calculating unit that calculates a correction amount for correcting the detection value of the drive sensor based on the acceleration caused on the scanning probe; a measurement data synthesizing unit that synthesizes the calculated correction-amount with the detection value of the drive sensor to acquire the position of the workpiece surface; wherein the correction-amount calculating unit includes a phase-difference correction-amount calculating unit, the correction parameter storage stores the correction parameter for correcting a phase difference, and the correction parameter (b in which Φ represents a phase-difference correction amount, f represents a rotation frequency during a scanning measurement and Φ 0 is an initial phase difference; and a result of scanning measurement of a circle gauge at different positions within a measurement area with different scanning velocities.