Abstract: For determining the optical quality of float glass, at an appropriate point on the production line a silhouette is produced on the projection screen of the float glass ribbon. The silhouette is detected by a video camera and evaluated by digital image processing. The luminance profile of the silhouette is determined from the video picture. The refractive power profile is calculated from the luminance profile and is digitally and/or graphically represented and evaluated.

Abstract: Process for manufacture of plate glass including pouring molten glass onto a bath of molten metal (4) contained in a tank having side wall (1), an inlet wall (2) and an outlet wall (3). The glass is advanced by means to form a glass ribbon (7) and extraction means draw the ribbon in a glass drawing space (II and III). Pairs of baffles (13 and 14) are positioned in the drawing zone between each side edge of the ribbon and the side walls to limit upstream flow of cooler molten metal in a direction towards the inlet wall.A device for manufacture of plate glass including a tank having an inlet wall (2), an outlet wall (3) and side walls (1) for holding a bath of molten metal (4) onto which molten glass is poured by feed means (6). The glass is advanced by advance means (9) in a drawing space to form a ribbon (7).