| 摘要 |
PURPOSE:To improve writing sensitivity and C/N of reading out and to permit easy control of tracking by the constitution in which the thickness in a recording track part of a recording layer is set at a specific value or below and the presence of absence of the pit after writing is detected by the reflected light of the reading out light from the rear side of a base body. CONSTITUTION:A base body 2 in a medium 1 is substantially transparent to writing light and reading out light, and grooves 3 for tracking are formed on one surface thereof. A recording layer 4 consists of a dye or dye compsn. and either one of the part above the recess of the groove 3 or the projecting part of a base body surface isolated by the groove 3 is used as a recording track part for forming pits. If the thickness (t) in the recording track part of the layer 4 exceeds 0.2mum, the writing sensitivity decreases. A decrease in the reflectivity and a decrease in the C/N of reading out are also resulted. The difference in the reflectivity between the recording track part and the other region is eliminated and the tracking control is difficult. |
