Fraunhofer Institute for Physical Measurement Techniques IPM
The thickness of invisible nanocoatings and their chemical composition can be determined based on the infrared-optical measurement of the reflective properties of surfaces. This method takes advantage of the fact that medium and long-wave infrared light (in the ranges of approx. 3–15 µm) is able to excite atoms in their molecular or lattice bonds to vibrate. Depending on the material, the vibrations occur at a specific wavelength and allow for quantitative conclusions regarding layer thickness and material composition – even in transparent components.
Measuring specific reflective properties to adopt them for process control
Infrared spectroscopy is an established laboratory analysis method but for technical and economic reasons it has not yet made its way into the production environment. However, industrial use at moderate cost has recently become possible – in particular in plasma coating processes. Adjusted lighting and novel detectors have enabled the development of compact and robust sensor technology, which can detect specific reflective properties. The measurement data is collected at the rate of production and can be used for quality assurance, for example in barrier coatings, as well as for process control. Fraunhofer IPM has extensive know-how and experience with the optimum setup, calibration and integration of application-specific infrared reflectometry systems.