| 摘要 |
A lens positioning method is provided. While vibrating an objective lens in the direction parallel with an optical axis, either the objective lens or a master disc in which a resist material has been formed as a film onto a substrate is moved, thereby changing a distance between the objective lens and a surface of the master disc. A return laser beam transmitted through the objective lens and reflected by the master disc surface is detected by a photodetector. When the master disc is located near a focal point of the objective lens, the return laser beam is detected by the photodetector. When the return laser beam is detected, the movement of either the objective lens or the master disc is stopped.
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