INFORMATIONSAUFZEICHNUNGSMEDIUM MIT GLASSUBSTRAT.

摘要

An information recording disk for recording an information signal along a track defined by a depression (13) on the disk as a change of physical property of a recording material deposited on the track comprises a disk-shaped glass substrate (16) made of a glass and carries a groove (13 min ) corresponding to the track. The groove has a surface roughness substantially smaller as compared to the surface roughness caused at a bottom surface of a groove on a silica glass substrate when both the disk-shaped glass substrate and silica glass substrate are dry-etched under same conditions. The disk-shaped glass substrate comprises SiO2 component and one or both of Al2O3 and BaO components with substantially no alkali components. Further, a recording layer (18) comprised of the recording material which changes in physical property responsive to a projected energy beam is deposited on the substrate (16) such that the depression (13) is formed in correspondence with the track.