| 摘要 |
PROBLEM TO BE SOLVED: To provide a glass substrate for a magnetic disk that is compatible with high recording density.SOLUTION: A glass substrate for a magnetic disk is characterized as follows: the glass substrate for the magnetic disk is provided with a main surface; an arithmetic average roughness Ra measured by an atomic force microscope in the main surface is 0.15 nm or less; an angular direction arithmetic average roughness Ra_deg in each angular direction of a predetermined area is calculated, based on results measured by the atomic force microscope, while changing an angular direction from 0° to 180° every 1°; and the value of (Ra_deg_max)/(Ra_deg_min) is 2.6 or less when the highest value among the calculated angular direction arithmetic average roughness Ra_deg is assumed as a maximum angular direction arithmetic average roughness Ra_deg_max, and the lowest value is assumed as a minimum angular direction arithmetic average roughness Ra_deg_min. Thereby, the problem is solved by providing the glass substrate for the magnetic disk.SELECTED DRAWING: Figure 3 |
