| 摘要 |
PURPOSE:To erase and record information even with the semiconductor laser of relatively low output and to prevent the life of the semiconductor laser from being shortened by switching and using the first beam splitter part and the second beam splitter part in accordance with each of recording, reproducing, and erasing. CONSTITUTION:In case of erasing and recording requiring high energy, a mobile beam splitter 21 is operated to insert a polarizing beam splitter 23 and a quarter-wave plate 24 as the first beam splitter part onto the optical path of the laser beam. Since the transmissivity of the laser beam is high in this case, erasing and recording is attained even through the semiconductor laser of relatively low output is used. In case of reproducing, the mobile beam splitter 21 is operated to insert a beam splitter 25 onto the optical path of the laser beam. |
