Glass thickness measurement

Noncontact glass thickness measurement based on the chromatic confocal measuring technique has become well established in glass manufacture as it allows glass thicknesses to be measured with µm accuracy even in difficult ambient conditions.

Flat glass inline

  • Multiple probe heads or traversing
  • Traversing width up to 6m
  • Hot and cold end
  • Data transfer to process control

Flat glass offline

  • Thickness
  • Planarity
  • Dimension

Container glass inline

  • In inspection machines or stand-alone
  • Cold and hot end
  • Retrofit into existing machinery

Container glass offline

  • Thickness
  • Contour (diameter, tilt, ovality)
  • Surface measurement
  • Cold and hot end

Thickness measurement of opaque material, such as:

  • heavily tinted glass
  • rough surface on both sides
  • metal sheets, plastic and suchlike

Measurement at the hot end

Specially developed cooled housings enable measurements to be made at glass temperatures of up to 1,000°C, i.e. before passing through the lehr. This drastically reduces the adjustment time for glass thickness configuration.

Measurement principle

Thanks to the large chromatic longitudinal aberration of the optical probes, white light is focused at different distances depending on the wavelength, i.e. the red focus is further away from the optical probe than the blue focus. Surfaces within this focal line reflect the light back into the optical probe and from here through the glass fiber into the spectrometer, where the distances to the optical probe and thus the glass thickness are determined from the reflected colors.