| 摘要 |
An optical head (10) focuses and irradiates a servo light beam onto at least one servo layer, and focuses and irradiates a recording/reproducing light beam onto a plurality of recording layers. An initial recording unit (20) records layer position information for specifying a position of each recording layer in advance in a predetermined position of each recording layer before recording user data in use of the recording/reproducing light beam, a layer position detection unit (21) reads layer position information in a predetermined recording layer by using the recording/reproducing light beam, and detects which one of the plurality of recording layers is the predetermined recording layer where the focal point of the recording/reproducing light beam is positioned, based on the read layer position information, and a seeking unit (22) moves the focal point of the recording/reproducing light beam to a target position based on the detected layer position. |
