| 摘要 |
PROBLEM TO BE SOLVED: To provide a measurement range wider than a measurement-possible range of an optical displacement gage while distance measurement and thickness measurement at high precision and resolution are allowed. SOLUTION: A distance between an optical displacement gage and a measurement point is measured first time by optical displacement gages 9 and 10 with a calibration plate 17 (thickness, known, = t0), and then the optical displacement gages 9 and 10 are moved toward a measurement point by 50μm and stopped for measuring a distance second time between the optical displacement gage and measurement point. This measurement operation is performed four times in all. Based on the measurement at each point, the position of measurement point is determined, and the measurement point position most frequently indicated is taken as a correct measurement point position to provide a distance (b) and a distance (c) between the measurement point position and the optical displacement gages 9 and 10, as well as movement distances (a) and (d) of the optical displacement gages 9 and 10 from reference points 9-0 and 10-0. The optical displacement gages 9 and 10 are moved on a measurement point line of an object 26 which is to be measured to provide distances (f) and (g) between the optical displacement gages 9 and 10 and measurement points, as well as movement distances (e) and (h) of the optical displacement gages 9 and 10 from the reference points 9-0 and 10-0. A thickness tx of the object 26 is calculated from tx=(a+b+t0+c+d)-(e+f+g+ h).
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