Measure the coating thickness and characteristics of tablets or pellets


The focus of the OSeeT are enteric coatings (EC) and modified-release (MR) coatings.


The characteristics of the coating layer are revealed via OSeeT:

Mean coating thickness
→  progress of coating process

Intra-particle and inter-particle coating variability
→  for quality and homogeneity of the applied coating

→  optical quality of the surface

The Technology behind OSeeT is Interferometry

  • OCT is based on white light interferometry:
    – broad bandwidth resulting in low-coherence length
    – defines the axial (=depth) resolution
  • Light is split into a reference and a probe path
  • Optics of sample arm focus light and define lateral (=surface) resolution
  • Interference of light reflected back from both paths
  • Spectrometer (grating, CCD line scan camera)
  • Depth-information is generated from interference fringes by Fourier-transformation (FFT)
  • Measurement of a single depth scan

More Information


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