Patent ID: 8904822

Claim:
A method of controlling a thickness between a first major surface and a second major surface of at least one preselected portion of a glass or plastic substrate comprising: providing a molten glass or plastic material; forming the molten glass or plastic material into a ribbon, the forming comprising applying a tension to edge portions of the ribbon; monitoring a thickness of the ribbon; identifying at least one thickness non-uniformity in the ribbon; preselecting at least one portion of the substrate in a viscous state corresponding to the identified thickness non-uniformity; and heating the at least one preselected portion of the ribbon in the viscous state with a laser beam directed to impinge on the preselected portion, wherein the heating causes the at least one preselected portion of the ribbon to attain a predetermined thickness, the heating comprising controlling at least one of a power, a residence time or a wavelength of the laser beam impinging on the preselected portion in response to the monitored thickness.