| 摘要 |
PURPOSE:To supply an optical type reproduction device which highly precisely reproduces encoded data in accordance with the intervals of marks by scanning reproduction laser beams whose phases are different and whose beam diameters are small on marks formed on a recording medium and detecting the diffracted light beams diffracted from the marks. CONSTITUTION:The reproduction laser beams are scanned on the plural marks arranged along the track of the recording medium 21. Data encoded in accordance with the intervals of the plural marks is reproduced. The device is provided with a semiconductor laser 11, a phase plate 15 giving a phase difference by pi to a part of the reproduction laser beams emitted from the semiconductor laser 11 and a transmission element 17 which gives an optical characteristic to the reproduction laser beams to which the phase difference is given and makes the beam diameters at the time of scanning by the track of the recording medium 21 small. |
