| 摘要 |
PROBLEM TO BE SOLVED: To improve measuring precision, by capturing accurate light shielding width of a laser beam, foreseeing change of conductivity and permeability of the surface of a measuring roller for every rotation angle position in the longitudinal direction of the measuring roller, foreseeing variable factors corresponding to change in the atmospheric temperature, and performing unified correction. SOLUTION: A sheet 2 as an object to be inspected is brought into contact closely with a measuring roller 1 capable of rotation. Laser measuring apparatuses 3 are arranged on both side ends of the measuring roller 1, and an eddy current type displacement gauge 8 is arranged above the measuring roller 1. A light shielding member 9 which moves together with the eddy current type displacement gauge 8 is arranged above a laser beam 7 of a projector 5 side of the laser measuring apparatus 3. Sum of distanceγbetween the tip of the eddy current type displacement gauge 8 and the tip of the light shielding member 9 and a light receiving widthβof the light receiving apparatus 6 side of the laser measuring apparatus 3 is substracted from a distanceαbetween the tip of the eddy current type displacement gauge 8 and the surface of the measuring roller 1, and the thickness T of the sheet 2 is measured.
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