| 摘要 |
PURPOSE:To read an information with a sufficient reliability even though the recording area per bit is made smaller and the intensity of a read signal light becomes weak. CONSTITUTION:A semiconductor laser 101 is held to have a single spectrum and a laser beam is outputted by periodically varying the optical frequency. The laser beam is split to a first beam which irradiates a magneto-optical disk 107 and a second beam which does not irradiate the disk and the optical path distances of the first and the second beams are made different. Thus, the light frequencies of the first and the second beams which are made incident to light receiving element 112 are made different. The reflected light of the first beam made incident on the magneto-optical disk 107 and the second beam are again mixed and are made incident on a light receiving element 112. If the electrical output caused by the optical frequency difference is extracted from the element 112, a recorded information is reproduced. |
