Fraunhofer Institute for Microstructure of Materials and Systems IMWS
Fraunhofer Institute for Microstructure of Materials and Systems IMWS

Analysis of optical thin-film systems

Thin film systems can control various optical properties through interference effects and are therefore of great importance for applications such as anti-reflective coatings, laser mirrors, spectacle lenses or optical filters to improve the performance of lenses and other components. Precise knowledge of the material structure of such multilayer coatings is crucial to ensure the performance of these functionalized systems. Using high-resolution methods of microstructure diagnostics and surface analysis, we can clarify effects at interfaces between substrate and coating system as well as between individual layers within layer stacks, investigate crystallization processes, create depth profiles or detect damage that can occur during the manufacturing process and in use (delamination, impurities, scratches). Thin-film structures can be analysed down to the sub-nanometer range and characterized, for example, in terms of layer thickness, homogeneity, crystallinity, particle distribution and fracture strength.

 

What we can offer

 

  • Many years of experience in failure analysis using state-of-the-art methods such as SEM-FIB (+EDX), HR-(S)TEM (+EDX), ToF-SIMS, XPS, AFM
  • Artifact-free sample preparation and high-resolution analysis of thin-film-based optical coatings from EUV to IR
  • Failure and defect analysis

 

What you can expect

 

We support our partners in

  • Diagnostics of coating systems and substrates down to the sub-nanometer range
  • Material evaluation for defined target regions (e.g. Defects)
  • Microstructural/detailed evaluation of targeted damage using test procedures (scratch test, LIDT)
  • Combination of microstructural and chemical information with sub-nanometer resolution and detection sensitivity in the ppm-ppb range
  • Reverse engineering and external sample analysis

 

Your benefits

 

  • Comprehensive experience through close cooperation with manufacturers of thin optical coatings/thin-film-based optical components
  • Microstructure-based process knowledge shortens development times and optimizes development processes
  • High-resolution defect diagnostics improves quality control capabilities and delivers precise results compared to indirect indications or conclusions based on assumptions
SEM top view and SEM FIB cross-sectional images of the damage to two highly reflective laser mirrors (45°, 355 nm), which were generated with different laser powers in individual pulses using a focused femtosecond laser (211 fs, 514 nm) . In all cases, the damage is clearly visible in defined layers of the coating system. The upper mirror, which was produced using ion beam sputtering (IBS), has a significantly lower surface roughness (inset) than the mirror deposited using magnetron sputtering (MS).