At each boundary layer of a transparent film incident light is partially reflected. To measure film thickness with the CWL FT, light from a whitelight source (LED, Xenon or Halogen bulb) is focussed onto the film and the spectrum of the reflected light is evaluated.
Due to the interference of the light from the boundary layers, the spectrum shows a typical waviness from which the sensor calculates the film thickness. Since the evaluated spectrum depends not only on the thickness, but also on the refractive index of the material, the parameter is included in the calculation of the thickness measurement.
measurement of transparent films and coatings
non-contact, non-destructive measurement
small spot enables highly resolved measurements
mapping in combination with MicroProf®
or MicroGlider® systems