Hot Glass Inspection Using Short-Wave Infrared Cameras

Achieving better goods quality and yield through automated vision has now become widely used for process control in many industries. Inspecting glass materials early in fabrication when manufactured objects are still hot is offering many benefits starting by a lower cost of rework if defaults are detected. The control of temperature uniformity during forming and cooling, the detection of defects (cracks, breakage, tamper, contaminant, chips) is essential to ensure quality, reproducibility and manufacturing efficiency. The hot glass inspection addresses numerous demanding markets (food packaging, beverages, pharmaceutical, building, …) in various forms such as bottle, packaging and tube. Generally characterised by high speed cadence, the hot glass inspection requires global shutter imagers.

Short Wave InfraRed (SWIR) cameras based upon InGaAs imagers work in a reflective imaging mode (like visible) and at the same time in detection mode of infrared radiation emitted by hot objects (>250°C). With a spectral response from 900-1700nm, they are particularly well adapted for hot glass inspection. Indeed, glass being transparent in this band, user can image through glass with details in the bulk and on both faces at the same time. SWIR cameras allows also non contact relative or absolute (if radiometrically calibrated) temperature measurement above 250°C up to 1800°C.