Patent ID: 6287663
Filing Date: 2001-09-11
Classification: G11B,Y10S,Y10T

Abstract:
A glass-ceramic substrate which is adapted to be formed into a magnetic information storage medium by coating said glass-ceramic substrate with a magnetic media, wherein said glass-ceramic substrate comprises a SiO.sub.2 --Li.sub.2 O--K.sub.2 O--MgO--ZnO--P.sub.2 O.sub.5 --Al.sub.2 O.sub.3 or a SiO.sub.2 --Li.sub.2 O--K.sub.2 O--MgO--ZnO--P.sub.2 O.sub.5 --Al.sub.2 O.sub.3 --ZrO.sub.2 system, said glass-ceramic substrate having a data zone and a landing zone, said data zone having a polished surface and having surface roughness (Ra) within a range of 3 to 9 .ANG., said landing zone having a multiplicity of projections or depressions being at a predetermined interval of 10-200 .mu.m, said projections and depressions being formed by rotating the glass-ceramic substrate while irradiating said substrate with a pulsed laser beam which is aimed vertically on the surface of said landing zone using sufficient laser power to form projections or depressions at a height within a range of 50 to 300 .ANG. and a surface roughness of 10 to 50 .ANG..