| 摘要 |
PROBLEM TO BE SOLVED: To provide a manufacturing method, for a magnetic recording medium, which comprises a laser texture machining method suitable for forming a small- diameter single-ridged bump. SOLUTION: A Gausssian beam from a pulse laser oscillator 1 is converted, by a beam converter 6, into a ring-shaped beam 7 in which a light intensity distribution in the section of the beam in its nearly ring-shaped part is strong as compared with the central part. The ring-shaped beam is deflected by a mirror 3, and it is passed through a condensing lens 4 so as to be condensed on the surface of a ring-belt region on the inner circumferential side of a substrate 5 which is turned and advanced side by side. Since a light intensity distribution becomes a ring shape in a section irradiated with a condensed spot, the temperature of the substrate 5 becomes high in a nearly ring-shaped part in the periphery as compared with the central part out of molten parts, and the surface tension of the substrate 5 is small. As a result, a molten material is gathered in the central part, and a single-ridged bump in a small diameter (3 to 6μm) is formed surely.
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