| 摘要 |
<p>PURPOSE: To improve the reproducibility of measurement by linearly synchronously transmitting a laser displacement meter in the direction of a rotary shaft answering to a position of a guiding step surface of a belt like recording medium and following the guiding step surface. CONSTITUTION: A control part 70 operates the light emission part 80 of the laser head part 55 of the laser displacement meter 50. Thus, a read surface 18 is irradiated by laser light L from the light emission part 80, and a drum supporting part 10 is rotated around the axis C integrally with a fixed drum 14. In such a case, a base 56 moves in the direction of the arrow Z (downward direction). In such a case, the base 56 and the laser displacement meter 50 move along the axis C of the fixed drum 14 answering to the rogical position of the read surface 18. The height of the read surface in such a case is obtained by a measuring position shown by a measuring point PM in the direction of the arrow Z. That is, a measured value becomes directly the data as it is.</p> |
