INFRAROT-FILMDICKENMESSANORDNUNG

摘要

An infrared film thickness gage for continuous on-line thickness measurement of a plastic film produced by a film blowing process into a tube shape has an infrared source with generally uniform directional radiation characteristics and is concentrically positioned inside the film tube. A photodetector is positioned outside the film tube in confronting relation to the source and receives the infrared rays of different reference and measurement wavelengths after the infrared rays have passed through the tube. Converting means receives the output of the photodetector, and since the film has different known attenuation coefficients for the different wavelengths, the thickness of the film can be determined. By using an infrared source having uniform directional characteristics and a filter to filter out instantaneous background light, measurement errors are substantially reduced or eliminated.