Imaging Methods for Quality Control
Requirements for the quality control of semi-finished products and components increasingly go beyond a pure imaging or topographic survey of the surface. Examples of this include functional coatings or cleanliness/purity requirements. This is why Fraunhofer IPM has steadily expanded its expertise in the area of the optical analysis of surfaces in the last four years. Imaging methods such as fluorescence measurement are particularly important in this respect since they allow not only the presence of a coating at a particular point but also the distribution and completeness of a coating to be checked.
In order to further develop the advantages of imaging for quality assurance, Fraunhofer IPM is working on making other, for the most part point-measuring, methods which have as yet only been established in the analysis laboratory such as laser-induced breakdown spectroscopy ready for use in the production line.
Inline Analysis beyond the Visible Spectral Range
Optical contrasts are not restricted to the spectral range of between approximately 400 and 800 nm visible to the human eye. Important contrast differences of certain materials cannot be seen until viewed in the short-wave infrared range of between 900 and 1,700 nm. What we call SWIR (short-wave infrared) cameras are used for this: unlike normal cameras, they are sensitive in this wavelength range and thus detect shapes and material compositions for which the contrast range of conventional cameras does not suffice.
Many non-transparent materials appear transparent to an SWIR camera. The reason for this is the spectral dependence of absorption and scattering characteristics. Reduced light scattering in the infrared range also enables process monitoring in environments containing steam or smoke.