Optical characterization

Fraunhofer IST offers numerous processes for the optical characterization of films and surfaces. Naturally our offering not only includes measuring but, if desired, also the analysis and interpretation of the measurement data. Various optical processes are used here in particular:



Ellipsometry is a contactless and non-destructive measuring process for determining various parameters such as the refraction index, layer thickness, roughness and additional parameters of optically transparent individual and multiple layers. Fraunhofer IST has a Sentech SENResearch 850 DUV available with the following features:

  • Wavelength range 190 – 2500 nm
  • Specimen size up to 6”
  • Specimen types: Transparent or opaque
  • Substrate: virtually any
  • Highly sensitive and low-noise cooled DUV detection system
  • Highly sensitive and low-noise FT-IR spectrometer
  • Computer-controlled goniometer for variable angle measurements (50 – 70 °)
  • Microspots with a beam diameter of 100 μm
  • Optional: wet cell for measurements under defined atmospheric conditions



Photometry is a fundamental discipline in the field of thin film optics. Virtually all issues in this field can be addressed thanks to 2 photometers, a Perkin Elmer Lambda 950 and an Agilent Cary 5000 UV-Vis-NIR. The repertoire is expanded by a Haze-gard Plus from the company BYK for rapid scattered light characterization.

Special capabilities:

  • Measurement of transmission in the range of 175 – 3300 nm
  • Measurement of reflection in the range of 175 – 3300 nm with incidence angles of 8 – 45 °
  • Measuring with polarised light
  • Measurement of haze (scattering) depending on the wavelength or by means of white light


Particle analysis

Suitable surfaces can be measured and evaluated in regards to their particle contamination with the help of confocal laser microscopy.  A process that was especially developed at Fraunhofer IST is available for this purpose, supporting the generation of particle load histograms. The particles that are found are divided into the following size classes: diameter less than 3 µm, 3 – 10 µm and over 10 µm. Here the detection limit is a particle diameter of approximately 700 nm.

Additional processes

  • Optical spectroscopy (FTIR, Raman, UV, Vis, IR)
  • Colour measurement: Determination of the coordinates in the colour space (CIE, L-a-b)
  • Scattered light measurement (haze): determination of diffuse backscattered light
  • Photovoltaics: IU characteristic curves, quantum yield, defect density (CPM), efficiency