Patent ID: 8225627

Claim:
A method for reducing a diameter of a bubble existing in a glass plate to be used as a glass substrate for a flat panel display, as window glasses of transportation vehicles, or as a photomask, comprising irradiating a vicinity of the bubble existing in the glass plate with a laser beam emitted from a laser light source, to raise a temperature of the glass in the vicinity of the bubble to at least a melting point of the glass to reduce a maximum diameter of the bubble, wherein the glass substrate is formed by a float method, a fusion method, a downdraw method, or by applying a redraw process to glass plate formed from a molten glass, wherein, prior to irradiating, the bubble is encapsulated by the glass plate and is under a surface of the glass plate, wherein before the irradiation of the laser beam, the bubble has an elliptical shape and d 1 and d 2 are perpendicular to one another and represent a major diameter and a minor diameter respectively of a shape of a bubble existing in the glass plate, wherein before the irradiation of the laser beam, at least 50% of bubbles existing in the glass plate satisfy formulas (1) and (2): d 1 >400μm (1) d 1 >2 d 2 (2) wherein due to the irradiation of the laser beam, the shape of the bubble changes to a spherical shape, the bubble floats to the surface of the glass plate and substantially disappears, or glass in the vicinity of the bubble expands thereby reducing the volume of the bubble.