Abstract: An on-line thickness gauge (OLTG) and method are described herein that are capable of measuring a thickness of a moving glass substrate. In the preferred embodiment, the OLTG includes a Y-guide and a stabilizing unit that respectively captures and stabilizes the moving glass substrate. The OLTG also includes a laser instrument which contains a laser source and a detector. The laser source emits a beam at the front surface of the moving glass substrate. And, the detector receives two beams one of which was reflected by the front surface of the moving glass substrate and the other beam which was reflected by the back surface of the moving glass substrate. The OLTG further includes a processor that analyzes the two beams received by the detector to determine a distance between the two beams which is then used to determine the thickness of the moving glass substrate.

Abstract: An inspection system for and a method of inspecting defects on opposite sides of a glass specimen are set forth wherein a focusing filament is positioned in the light path of an inspection system having an objective lens. The filament is focused to the same plane that the objective lens uses to image a defect on the glass surface, so as to produce a shadow of the filament in the field of view when the objective is focused on either a front or back surface of the specimen. The utilization of the focusing filament provides an absolute surface reference that can automatically compensate for variations of the glass specimen position relative to a plane.

Abstract: An inspection system is set forth for the inspection of surface and body defects within glass substrates. The glass is supported by an inclined air table during the inspection process to provide planar stability and minimize vibration. The sheet is indexed a given distance along an oblique axis parallel to the air table and stopped, wherein a scanning mechanism having portions on opposite sides of the air table moves transversely of the sheet in alignment with slots formed in the air table, and the process is repeated until the sheet is completely scanned.