| 摘要 |
PROBLEM TO BE SOLVED: To accurately detect a displacement less than a pixel unit in a displacement detector for detecting the displacement of a body, utilizing the image processing. SOLUTION: An A-D converter 102 converts an analog image taken by an imaging means 101 to a digital image which is then stored in a reference image storing means 104 and an image storing means 105. A first displacement measuring means 106 detects displacement values (Δx,Δy) in pixel unit. A second displacement measuring means 107 detects displacement values (δx,δy) less than the pixel unit by the time-space differentiation, based on two images and the displacement values (Δx,Δy) in pixel unit. They are added to output accurate displacement values defined by (Δx+δx,Δy+δy).
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