| 摘要 |
PURPOSE:To obtain an inexpensive device easy to adjust and make overwriting possible by irradiating two beams from one optical head and allowing the erasing beam to precede the recording and reproducing beam. CONSTITUTION:The beam from a laser light source 11 is divided to two beams by an acoustooptic element (A/O element) 12-1, and one beam is focused at a position 14 on a recording surface as the recording and reproducing beam. The other beam is focused as a position 15 as the erasing beam by a lens 13 and precedes the recording and reproducing beam. In such constitution, information is written with the recording and reproducing beam at the recording time while erasing recorded information with the erasing beam, and the output of the erasing beam is reduced and information is reproduced with the recording and reproducing beam at the reproducing time. Thus, the structure is simple and inexpensive, and the adjustement is made very easy because of one A/O element, and overwriting is made possible.
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