| 摘要 |
PURPOSE:To provide overwrite without generating an unerased part in an optical information recording and reproducing device using a phase change recording medium. CONSTITUTION:A beam emitted from a semiconductor laser 1 is changed to parallel rays by a collimator lens 2, and they are changed to the parallel rays in almost circular shape by a shaping prism 3. Intensity modulation is applied to a peripheral part in parallel with a tracking direction synchronizing with the modulation of laser by an A/O modulator 9, and the beam is converged as an ordinary convergence spot in recording, and as a convergence spot with low effective NA in erasure. Thereby, spot width when the erasure is performed can be increased than a recording pit. |
