OPTICAL RECORDING MEDIUM

PROBLEM TO BE SOLVED: To provide an optical recording medium whose double refraction is within a standard value and which is integrally formed. SOLUTION: The optical recording medium has a substrate, an information recording surface provided on the substrate and a clamping area protruded at the center part of the substrate. A turbulent flow of a resin stream generated at the boundary part between the substrate having 0.6 mm thickness and the clamping area having 0.85 to 0.95 mm thickness is suppressed, it is prevented that double refraction of the boundary part is more than 100 to be the standard value and compatibility with a reproducer can be secured by the clamping area having 0.85 to 0.95 mm thickness. COPYRIGHT: (C)2004,JPO