| 摘要 |
PURPOSE:To reproduce information recorded on each optomagnetic recording layer individually by splitting a laser beam having a wavelength corresponding to the optomagnetic recording layer and detecting individually a Kerr rotation angle difference. CONSTITUTION:The thickness of the 1st magnetic recording layer 16 is selected preferably between 100Angstrom -120Angstrom , a Kerr rotation angle difference deltathetak of >=0.3 deg. corresponds to, e.g., information [1] and the difference of <=0.3 deg. corresponds to, e.g., information [0], then the information of the 1st magnetic recording layer 16 is reproduced with a laser ray of wavelength 8,300Angstrom and the information of the 2nd magnetic recording layer 20 is reproduced by a laser ray of wavelength 7,800Angstrom . Thus, the Kerr rotation angle difference corresponding to the vertical magnetizing direction stored in the 1st magnetic recording layer 16 is obtained surely by the reflected light of wavelength lambda1 from the optomagnetic disc 10. Thus, a signal corresponding to a data stored in the 1st magnetic recording layer 16 is obtained surely. Similarly, a signal corresponding to the data stored in advance in the 2nd magnetic recording layer 20 is obtained surely even in a reflected light of wavelength lambda2 from the optomagnetic disc 10. |
