Chromatic Sensor CWL FT - Interferometric Film Thickness Sensor
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.


Sensor: CWL FT



Measuring Principle
   
  • 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
  • small, wear-free sensor without moveable parts

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Typical Applications
 
  • measurement of foils in the food industry
  • control of blister packaging
  • thickness mapping on semiconducturs
  • varnish measurement for the automotive industry
  • examination of multilayer systems such as air gaps
    below transparent covers


Technical Specifications
   
working distance 9 mm 26 mm
light source  LED                             Halogen/Xenon  LED                             Halogen/Xenon
measuring range 1 3 µm ... 180 µm          2 µm ... 250 µm 3 µm ... 180 µm          2 µm ... 250 µm
resolution x,y < 5 µm < 20 µm
measuring angle 90° ± 10° 90° ± 5 °
resolution film-thickness 10 nm
wavelength range approx. 350 nm ... 850 nm
 1 For refractive index of n=1

Technical specifications and content are subject to change.