Abstract: Methods and apparatus for controlling glass flow in, for example, a downdraw glass manufacturing process (e.g., the fusion downdraw process) are provided. In certain aspects, the mass, thickness, and/or the temperature distribution of molten glass (40) on the surface of forming apparatus (60) is managed by: (A) constructing a stream-tube mapping between (i) regions (510; FIG. 5A) of a cross-section of a conduit (400) that supplies molten glass (40) to the forming apparatus (60) and (ii) regions (510; FIG. 5B) on the exterior surface of the forming apparatus (60); (B) using the stream-tube mapping to select a temperature distribution for the cross-section that results in a desired mass, thickness, and/or temperature distribution of molten glass (40) on the surface of the forming apparatus (60); and (C) heating and/or insulating the conduit (400) so as to produce a temperature distribution for the cross-section which equals or at least approximates the distribution selected in step (B).

Abstract: Methods and apparatus for controlling glass flow in, for example, a downdraw glass manufacturing process (e.g., the fusion downdraw process) are provided. In certain aspects, the mass, thickness, and/or the temperature distribution of molten glass (40) on the surface of forming apparatus (60) is managed by: (A) constructing a stream-tube mapping between (i) regions (510; FIG. 5A) of a cross-section of a conduit (400) that supplies molten glass (40) to the forming apparatus (60) and (ii) regions (510; FIG. 5B) on the exterior surface of the forming apparatus (60); (B) using the stream-tube mapping to select a temperature distribution for the cross-section that results in a desired mass, thickness, and/or temperature distribution of molten glass (40) on the surface of the forming apparatus (60); and (C) heating and/or insulating the conduit (400) so as to produce a temperature distribution for the cross-section which equals or at least approximates the distribution selected in step (B).

Abstract: A method of measuring dimensional changes in a transparent substrate includes forming an array of reference markers on a reference plate, forming an array of substrate markers on the transparent substrate, stacking the reference plate and transparent substrate such that the reference markers and substrate markers overlap, measuring coordinates of the substrate markers relative to coordinates of the reference markers before and after processing the transparent substrate, and determining dimensional changes in the transparent substrate from the difference between the measured relative coordinates of the substrate markers before and after processing the transparent substrate.