| 摘要 |
PROBLEM TO BE SOLVED: To provide a light-transmissive substrate for optical information medium, hardly generating warping and the like and further having an optical characteristic low in double refraction index. SOLUTION: A light-transmissive substrate for an optical information medium is a substrate through which recording light is transmitted, and which is used as an optical information medium recorded with an optically readable signal. A gate for injection molding of a disk-like light transmissive substrate 1 having a center hole 4 at the center is on the inner peripheral side of the substrate 1. In the region inside the range, in which the recording region is formed from the inner peripheral side of the substrate 1, plural steps which gradually become thicker as it goes to the outer peripheral side are formed. An optical information medium using this substrate 1 has a recording layer 12 formed on this substrate 1 and a reflection layer 13 formed on this recording layer 12 and reflecting regenerated light. |
