| 摘要 |
Resin, typically polycarbonate is injection molded into a disc substrate under select conditions, for example, at a mold temperature of 100-160 DEG C., an injection velocity of 100-120 g/sec., and a pressure of 10-60 kg/cm2, such that the birefringence of a radially inner portion of the substrate is higher by about 15-50 nm than the remaining substrate. A center hole is perforated in the substrate and a hub is attached to the substrate around the center hole. At the end of hub attachment, the substrate has a uniform distribution of birefringence over the entire area. Any increase of DC modulation is thus avoided.
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