| 摘要 |
PURPOSE:To evenly carry out releasing of the substrate and a stamper and to keep down variation in birefringence of the substrate in the circumferential direction by forming a group or a bit over the whole surface of an information recording surface. CONSTITUTION:The group for tracking (guide groove) 4 in the information recording range 3 and another similar group 7 as in the information recording range 3 outside the information recording range 6 are provided on the information recording surface 2 of the substrate 1. Here, a border line range 8 without any group is provided for a width of two to several mum between the group 4 of the information recording range 3 and the group 7 outside the information 6 to discriminate the two ranges. Furthermore the group 7 is formed over the whole substrate to outer periphery of end face 12 of the most outer periphery or central hole 11 of the innermost periphery. Thus, the surface roughness of the substrate 1 is identical all over its surface, the substrate 1 and the stamper can be released smoothly and evenly, and there is no great variation in the birefringence distribution in the circumferential direction of the substrate 1. |
