| 摘要 |
PROBLEM TO BE SOLVED: To provide an apparatus and a method wherein the minor diameter or the displacement of a cylindrical inner circumferential face is detected at high speed and with satisfactory accuracy, by a displacement measuring part situated at the outside of the cylindrical inner circumferential face for a dynamic-pressure fluid bearing and the cylindrical inner circumferential face is inspected or the like. SOLUTION: A measuring-object raising and lowering device 12, a raising and lowering device 16 for focusing used to raise and lower a laser-displacement-gage holder 14 and a support base 20 for a reflecting-surface-holding-part turning device 18 are installed on a base 21. The turning device 18 turns a pillar-shaped reflecting- surface holding part 24 comprising a reflecting surface 24 in its upper end. The device 16 raises and lowers the holder 14. A laser displacement gage 26 detects the displacement of a measuring object on the basis of reflected light returned on the same axis line as an emitted laser beam. The axis line of a laser beam emitted from the displacement gage 26, the axis line of the holding part 24, the rotating axis line of the turning device 18, and the axis line of a sleeve member 22 held by a measuring-object holder 10 agree, and a reflecting surface 24a is tilted by 45 deg. with reference to the axis line of the laser beam.
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