| 摘要 |
PURPOSE:To prevent the deterioration of recording and reproduction caused by fluctuations of temperature of a digital optical disk, by using a spacer which has a coefficient of thermal expansion matched with those of the substrates or protecting member of optical disks when bonding the substrates or substrate and protecting member mutually with the spacer between. CONSTITUTION:When the substrates 3 and 3 each formed by providing a recording member 2 to a reinforced glass disk 1 are bonded together with the spacer 4 between, or when the protecting member 12 and substrate 3 are bonded together with the spacer 4, the spacer made of alloy consisting of =>2 elements among Ni, Fe, Cr, Co, Cu, Mo, and Ti is used to match the coefficient of thermal expansion of the glass disk 1 or protecting member 12 with that of the spacer 4. Consequently, the strain, curvature, etc., of the disks and protecting member due to the difference in expansion between the disks 1 and protecting member 12, and spacer 12 due to temperature fluctuations and the evil influence of double reflection are prevented during recording and reproduction by semiconductor laser light 6. |
