| 摘要 |
PURPOSE:To easily change over a level in a recording mode and in an ultralow- power reproducing mode by using an optical-intensity attenuation element whose optical transmittance is controlled according to the changeover of a recording mode and a reproducing mode. CONSTITUTION:A laser beam from a semiconductor laser 51 is shone at an optical recording medium 110 via an optical system including a dichroic mirror 70, a reflected beam from the medium 100 is incident on a photodetector 56 via the mirror 70 and a beam splitter 53, and a recording operation and a reproducing operation are performed. An optical-intensity attenuation element 401 is installed in an optical path between the laser 51 and the mirror 70. The element 401 becomes transmissive in a recording mode and becomes attenuant in a reproducing mode via an optical-intensity-attenuation control system according to a mode changeover by a recording-and-reproducing-mode changeover circuit 512. Thereby, an optical-intensity level can be changed over easily and surely in a recording mode and in an ultralow-power reproducing mode. |
