| 摘要 |
PURPOSE:To write data to a recording medium regardless of the change in the lapse of time of the slope efficiency of a laser light source by detecting the level of a laser light corresponding to the prescribed pattern of writing data and controlling to output the light of the prescribed writing level with a laser light source. CONSTITUTION:Writing data WD have a prescribed training pattern and a writing data pattern and a light output PL of a laser diode 23 comes to be the emitting light of a prescribed level in accordance with the training pattern. The voltage for compensation from a differential circuit 35 is a light output level of the part reduced by the deterioration in the lapse of time to a slope efficiency eta of the laser diode 23, the reduced output is compensated by a current iC2 of a current source 26 for compensation and a power sufficient to the writing can be obtained. Thus, in order to control the output level of a laser light source at the time of writing the data by a prescribed pattern, the data can be written to the recording medium regardless of the change with passage of time of the slope efficiency of the laser light source. |
