| 摘要 |
PURPOSE:To decrease the double refraction to be generated in an optical disk substrate by executing fixing of the engaging position determining member to the optical disk substrate only in the part where the member and the substrate face each other. CONSTITUTION:The fixing of the engaging position determining member 2 to the optical disk substrate 1 is executed only in the narrow range near the central hole of the substrate 1 which is a part of the parts where said member and substrate face each other. As the contact range is narrow, the stress to be generated in the disk 1 by solidification of an adhesive agent 3 and by the thermal expansion occurring in the temp. change of the environment where the optical disk 1 is used is decreased. In addition, the stress, even when generated, does not affect the recording region as the generated part is far from the recording region. The fixing power between the substrate 1 and the member 2 and double refractions in the substrate 1 are most adequately selectable by changing the central hole diameter of the substrate 1 and the width B in the fixing part as desired. |
