| 摘要 |
PURPOSE:To increase the write amount of a specimen on a table by measuring the position of a mirror, which uses a peripheral surface coaxial with the rotational center of a rotary table as a mirror surface, with the aid of a laser beam and a lens and measuring properly the position of the rotary table. CONSTITUTION:The table 11 is placed on a base and moved in right and left directions. On the upper surface, the rotary table 21 is provided which uses a rotational center 14 as a center and an outer periphery 21A as a cylindrical mirror, and thereon the specimen is placed. Then the laser beam 19 emitted from an interference meter 18 irradiates the outer periphery 21A through a cylindrical lens 22 on the table 11, reflected to return to the interference meter 18 through the lens 22, whereby a distance between the interference meter 18 and the table 21 is measured. The lens 22 is focused at the rotational center 18 of the table 21. The measurement of the distance means the measurement of the table 21 itself, and is made by controlling displacement so that the position error of the table 21 cannot exert influence. As a result even if write and read pitches with respect to the specimen are made smaller, the measurement can be possible, and the write amount can be increased. |
