Method of manufacturing a circular optical storage disc and circular optical storage disc

Abstract

In the method of manufacturing a circular optical storage disc (10), an extension body (21) is present around the substrate (11) of the optical disc (10) during the spin coating of cover or spacer layers (15). The extension body (21) may consist of one or several pieces. The outer periphery (23) has a circular or polygonal shape. The inner periphery of the extension body is in close circumferential contact with the periphery (13) of the optical disc substrate (11). The surface (22) of the extension body is substantially flush with the surface (12) of the substrate (11) of the optical disc in order not to impede the flow of spin coating liquid during spin coating. The raised edge (16), which usually forms at the periphery (13) of the substrate (11) is now transferred to the outer periphery (23) of the extension body (21). After the coating operation the extension body (21) is removed. By choosing a surface (22) to which the coating (15) adheres poorly, reuse of the extension body (21) is facilitated. The manufactured optical storage disc (10) has no or a very small raised edge (16), and the method causes no extra birefringence.

Dependencies are inferred from the claim text.