| 摘要 |
PROBLEM TO BE SOLVED: To enable measuring film thickness safely and precisely with simple facility by obtaining a distance between an ideal spherical body and a magnetic field generating device from magnetic field intensity, measuring a distance between the lower surface a film and the terminal of an optical displacement measuring means, and obtaining the difference of both the distances. SOLUTION: A steel ball 2 is put on the upper surface of a film 1. Under the film 1, a terminal 3 of a magnetic field generating device 5 is adjacently arranged in a noncontact manner. A magnetic field is generated with the device 5, and the terminal 3 is moved along the rail 9. The steel ball 2 is attracted by the terminal 3, and follows it while rotating. When catenary or thickness irregularity exist in the film 1, difference of magnetic field intensity appears between the steel ball 2 and the terminal 3. By detecting the change of field intensity due to movements of the ball 2 and the terminal 3, the distance l2 between the ball 2 and the terminal 3 is measured. Light is emitted from a terminal 4 of an optical displacement measuring device 6, and the reflection from the lower surface of the film 1 is measured. Thereby the distance l1 between the terminal 4 and the lower surface of the film 1 is measured. The difference l2-l1 is equal to the film thickness.
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