REDUCTION METHOD FOR INTEGRATED SYSTEMATIC ERROR OF DISPLACEMENT, REFERENCE IMAGE RENEWING CIRCUIT, DISPLACEMENT MEASUREMENT SYSTEM BASED ON IMAGE CORRELATION, RECORDING MEDIUM AND CARRIER WAVE

摘要

PROBLEM TO BE SOLVED: To provide a reduction method for integrated systematic error of displacement which is capable of reducing integrated systematic error in an image correlation system requiring resolution of a sub-pixel unit. SOLUTION: In an optical position converter 100, a reference image is renewed when predetermined parameters are fulfilled. An image corresponding to the displacement of a coarse optical surface 104 is captured with a reading head 126 and stored. The reference image and the captured image are compared with different offset in a displacement direction. When the displacement is within a predetermined set value or a sample time corresponding to the displacement, the reference image is renewed. By renewing the reference image in this manner, the integration of systematic error is prevented and thus, the systematic error in the image correlation system can be eliminated.