| 摘要 |
PURPOSE: To provide a manufacturing method for an optical disk base of long- term stability and heat resistance and provided with almost zero birefringence on all over the whole surface of the disk even after annealing. CONSTITUTION: This manufacturing method consists of a process of molding a disk-shaped or doughnut-shaped plastic base formed by using the injection molding method and a process of annealing the plastic base at the temperature lower than the glass transition temperature of the plastic base by 10 deg.-60 deg.C for 1-6 hours. In the molding process, the plastic base providing the birefringenece distribution in the radius direction is uniformized after annealing by adjusting the temperature of a mold. |
