| 摘要 |
PURPOSE:To improve the function of an optical recording and reproducing device by recording and reproducing a signal by means of an approximately circular micro light spot and erasing freely the recorded signal by a rectangular light spot. CONSTITUTION:A divergent beam emitted from semiconductor lasers 12 and 14 goes to parallel beams (i) and (k) by collimate lenses 22 and 24. Assuming that the semiconductor laser used for recording and reproducing and that used for erasing are 12 and 14, respectively, the parallel beam (i) is shaped so that the aspect ratio of the beam can be minimized by the 1st prism 23, and the aspect ratio goes to approximately '1'. The beam is changed to a right angle by a light synthesizer 32, passes through about the center of a polarization beam spliter 31, a lambda/4 plate 4, a mirror 39 and an objective lens 5, and forms an approximately circular light spot in the center of the recording line of a disk. On the other hand, the parallel beam (k) is refracted by the 2nd prism 8 so that its aspect ratio can be maximized, and said ratio goes to approximately 10. This beam passes through the light synthesizer 32, and afterwards it progresses in the same manner as the beam (i) and forms an elliptical light spot having a long diameter in the tangent direction of the recording line of the disk.
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