| 摘要 |
PURPOSE:To secure a satisfactory reading contrast of a mark image by forming a lamination of a 1st magnetic layer having a high Curie temperature and a low coercive force and a 2nd magnetic layer having a relatively low Curie temperature and a high coercive force. CONSTITUTION:The magneto-optical recording mediums 6 and 30 of an exposure device containing a positioning optical system 9 set distant from the optical axis of a projecting optical system 3 and a recording medium 4 set on a mobile stage 5 are formed with lamination of a 1st magnetic layer 23 having a high Curie temperature and a low coercive force and a 2nd magnetic layer 22 having a relatively low Curie temperature and a high coercive force. At the time of exposing a magnetic field larger than the coercive force of the layer 23 is applied in the direction where the magnetization of the layer 23 is inverted together by irradiating it with the mark light via the system 3. Thus the temperature of the layer 22 exceeds the Curie point and the magnetization of the layer 23 is inverted. When the irradiation of the mark light is cut off, the temperature of the layer 22 falls and the magnetization of the layer 22 is inverted in the stable direction to the layer 23 in response to the magnetization of the layer 23. Then a mark image is recorded. Thus a satisfactory reading contrast is secured to the mark image and this image can be detected with high accuracy. |
