| 摘要 |
PURPOSE:To permit improvement of long-term weatherability and maintenance of a high reflectivity by using a thin film of copper as a reflection film. CONSTITUTION:The thin film of copper is used as the reflection film. The reflectivity of the copper constituting the reflection film of an optical disk is higher than the reflectivity of aluminum and is about 93% at the wavelength (0.6-0.8mum) of laser light to be normally used. Since copper is nobler than aluminum and is chemically stabler, the long-term weatherability is improved and the high reflectivity is maintained with the optical disk. The purity is preferably >=99.9wt.% and the film thickness >=100Angstrom with the thin film or copper constituting the reflection film. The optical disk is liable to be adversely influenced by external chemical materials and impurities contained in the thin film if the purity is <99.9wt.%. The mechanical strength and the light reflectivity are insufficient if the film thickness is <100Angstrom . The more preferably film thickness is >=200Angstrom . The long-term weatherability is thereby improved and the high reflectivity is maintained. The good image quality is thus obtd. |
