| 摘要 |
A video disc member is described having a unirorm value of birefringence over the entire information storage surface of the disc. This value of birefringence is the same at the inner information storate radius as at the outer information storage radius. The preferable composition of the video is a specially prepared poly methylmethacrylate, referred to as PMMA. The method of molding the improved video disc member includes an extended drying time for said composition and increasing the melting temperature. The increase in melt temperature provides a low and uniform value of birefringence. The improved drying cycle eliminates splay marks, blisters and other surface inferfections as compared to manufacturer recommended drying times.
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