Method for manufacturing annular glass plate, method for manufacturing glass substrate for magnetic disk, and method for manufacturing magnetic disk

Abstract

A method for manufacturing an annular glass plate that has an outer circumferential edge surface, an inner circumferential edge surface, and a thickness not larger than 0.6 mm includes processing for manufacturing an annular glass plate by irradiating each of the outer circumferential edge surface and the inner circumferential edge surface of an annular glass blank with a laser beam to melt the outer circumferential edge surface and the inner circumferential edge surface and form molten surfaces such that the molten surfaces in the outer circumferential edge surface and the inner circumferential edge surface each have an arithmetic average surface roughness Ra not larger than 0.1 μm, and the surface roughness of the molten surface in the inner circumferential edge surface becomes larger than the surface roughness of the molten surface in the outer circumferential edge surface.

Dependencies are inferred from the claim text.