| 摘要 |
<P>PROBLEM TO BE SOLVED: To provide a glass substrate for a magnetic recording medium that when surface roughness Ra of an outer peripheral side surface portion of an outer peripheral end surface is measured at a plurality of points, has a maximum value and a standard deviation of the surface roughness Ra falling within a predetermined range and is excellent in parallelism when polishing of a main plane is performed. <P>SOLUTION: There is provided a glass substrate for a magnetic recording medium in which, when surface roughness Ra is measured at total 24 points of measuring points of an outer peripheral end surface provided at intervals of 15 degrees of a central angle on the outer peripheral end surface of the glass substrate for the magnetic recording medium, a maximum value of the surface roughness Ra of an outer peripheral side surface portion of the outer peripheral end surface is 0.5 μm or less and a standard deviation of the surface roughness Ra of the outer peripheral side surface portion is 0.2 μm or less. <P>COPYRIGHT: (C)2013,JPO&INPIT |
