| 摘要 |
PURPOSE:To prevent the decrease of signals from address bits and to narrow a track pitch by interrupting the grooves for tracking in the part adjacent to the respective address bits in an address bit part. CONSTITUTION:The grooves 1 for tracking are not formed in the part adjacent to the address bits 2 in the address bit part and are interrupted by as much as the length of the bits 2 in the part of the bits 2 to form a grooveless section 3. The exposing of the grooves for tracking is thereby prevented at the time of exposing the address bits and, therefore, the fogging by the overlap of the two laser beams for exposing is prevented and the decrease of the signals from the address bits is prevented even if the track are formed to the smaller pitch. Since the section 3 is short in length, the tracking is not hindered. The formation of the tracks to the smaller pitch is, therefore, possible. |
