| 摘要 |
PURPOSE:To reduce the time for data transfer or data write in same recording medium by providing plural beam control means controlling plural laser beams. CONSTITUTION:An optical spot al constituting a beam group preceding in a progressing direction of a track is a beam spot for reproduction, an optical spot a2 is an erasure beam spot and irradiated from an erasure multi-beam semiconductor laser into the track. On the other hand, an optical spot a3 constituting a succeeding beam group in the progressing direction is a recording beam spot, and an optical spot a4 is a recording confirmation beam spot and irradiated to the track from a write multi-beam semiconductor laser 4'. The optical spots a1, a2 are controlled by the 1st control means and the optical spots a3, a4 are controlled by the 2nd control means. The erasure and recording, or the erasure, recording and reproduction, or the erasure and reproduction are executed at the same time respectively. |
