| 摘要 |
PURPOSE:To obtain an original disk which is high in recording density and also is uniform in width and depth of a tracking guide and an information bit by providing an upper layer and a lower layer, providing the first recessed part on the upper layer, and providing the second recessed part which comunicates to the first recessed part and is narrower than its width, on the lower layer. CONSTITUTION:As for a quality of material of a lower layer 2B, that which generates deformation or evaporation by heat such as a semi-metal or Te, Bi, Se, etc. is used, and as for an upper layer 2A, a heat sublimating substance such as nitrocellulose containing organic coloring matter and carbon, etc. are used. Thickness T1 of the upper layer 2A coincides with optimum depth size + or -lambda/8+ nlambda/2 of a tracking guide, and thickness T2 of the lower layer 2B is set to a value which subtracts the size T1 from optimum depth size + or -lambda/4+nlambda/2 of an information bit. A tracking guide 3 of the first recessed part whose width C1 and depth are d/2 and T1, respectively is formed on the layer 2A. The second recessed part which communicates to the guide 3 and has width C2 (C2<C1) is formed by depth T2 as an information bit 4 on the lower layer 2B. Accordingly, since the bit 4 is formed in the guide 3, the track pitch can be narrowed. The depth is made uniform by T1 and T2. |
