Imaging procedures for quality control

Imaging inline surface analysis

Surface properties of semi-finished products and components in production are essential for the later functioning of the component or for carrying out subsequent processes in production. That is why more and more surface properties are being inspected in production. Fraunhofer IPM offers customized systems for surface inspection in the production line. Systems for testing and inspecting the following properties are realized:

  • Presence and quality of coatings (material, thickness, ...)
  • Surface purity (cinematic and particulate impurities)
  • Defects on surfaces

An important aspect in the setup and configuration of these test methods is the fact that the test usually has to cover large areas on the surface or even the entire component or semi-finished products. For example, surface cleanliness generally has to reach a certain quality on the entire component in order to guarantee a high-quality finish on the entire surface during the subsequent processing step.

One focus of the work at Fraunhofer IPM is therefore on imaging methods with which entire surfaces can be quickly tested for specific properties. Optical methods are very well suited for this because they not only enable imaging, but also work without contact and they work fast.

Currently, the following procedures are available; further customized new developments are available on request.

Imaging fluorescence measurement technology

With the systems F-Scanner and F-Camera, it is possible to create images that show the distribution of intrinsic fluorescence on the surface. Filmy contaminants consisting of fluorescent organic substances are detected very precisely in this way. Their distribution is rendered very clearly in an image. The thickness and completeness of transparent, organic coatings is also tested spatially.

Image capture with application-specific lighting

The F-Camera system also offers the possibility of creating contrasts with adapted illumination and detection arrangements, thus making visible surface structures and defects that are not recognized by conventional arrangements.

Imaging infrared measurement technology

In short-wave infrared, the part of the light spectrum with a wavelength between 900 to 1700 nm, one finds contrasts of certain materials, which are not possible in the visible spectral range. For example, in a part of this wavelength range, water is highly absorbent. In this way, water residues and moisture on surfaces can be detected. On the other hand, e.g., some colored plastic components are transparent, which means structures and defects inside these components can be detected.

Laser-induced plasma spectroscopy

This method irradiates the surface with an intense laser pulse, which transfers material from the surface into a so-called plasma. The glow of this plasma provides information about the material composition. In order to further exploit the advantages of imaging for quality assurance, Fraunhofer IPM is working to use this point-measuring method previously used only in the analysis laboratory also in production lines.