GLASS SUBSTRATE FOR A MAGNETIC DISC AND PROCESS FOR ITS GLASS SUBSTRATE FOR A MAGNETIC DISC AND PROCESS FOR ITS PRODUCTION PRODUCTION

摘要

A glass substrate for a magnetic disc having a finely and isotropically roughened surface, wherein the maximum height Rmax of the surface roughness is substantially not higher than 700 ANGSTROM at a standard length of 250 mu m and substantially not less than 50 ANGSTROM at a standard length of 50 mu m.