| 摘要 |
<p>OF THE DISCLOSUREThe present invention relates to a glass substrate for a magnetic recordingmedium, including: a pair of main surfaces; an outer peripheral surface; and an inner5 peripheral surface, in which the outer peripheral surface includes an outer peripheral side surface portion and an outer peripheral chamfered portion, in the outer peripheral surface, when a surface roughness Ra is measured at a total of 24 measurement points, provided at intervals of 15 degrees in central angle of the glass substrate for a magnetic recording medium, with a cut-off value at 64 pm, a maximum value of the10 surface roughness Ra of the outer peripheral side surface portion is 0.5 pm or less, and a standard deviation of the surface roughness Ra of the outer peripheral side surface portion is 0.2 pm or less a difference in the surface roughness Ra of the outerperipheral side surface portion between adjacent measurement points on the outer peripheral surface is 0.3 µm or less, a maximum value of a surface roughness Ra of the15 outer peripheral chamfered portion is 0.5 pm or less, a standard deviation of the surface roughness Ra of the outer peripheral chamfered portion is 0.2 pm or less, and adifference in the surface roughness Ra of the outer peripheral chamfered portion between adjacent measurement points on the outer peripheral surface is 0.3 µm or less. Fig. 1</p> |
