| 摘要 |
PURPOSE:To improve the erasure rate at the time of overwriting by synthesizing two laser light of each different wavelength on the same optical axis by a half mirror and condensing it onto a recording medium. CONSTITUTION:A recording laser light is emitted from a recording laser light source 1, and condensed onto the medium recording surface S by a condensing lens 4. On the other hand, an erasing laser light is emitted from an erasing laser light source 2 by wavelength being different from that of the light source 1, synthesized so that the optical axis becomes the same as the recording laser light by a half mirror 3, and thereafter, condensed to the surface S by the lens 4 together with the recording laser light. When a laser light whose wavelength is longer than that of the recording laser light is used as the erasing laser light, the spot diameter of the erasing laser light can be made wider than the spot diameter of the recording laser light, and a wider range than width of a recording mark can be allowed to ascend to an erasing temperature. In such a way, when overwriting is executed, the erasing remainder can be decreased. |
