Infrared Metrology as Qualification for Developing New Infrared Opacifiers and Functional Coatings


Several FTIR- and diffraction-spectrometers are available at ZAE Bayern to cover the whole wavelength range from the ultraviolet up to the far infrared spectral region. To quantify the radiative heat exchange between surfaces or the radiative heat transfer through materials, respectively, measuring of thermal radiation is necessary (Fig. 1). Due to multiple extensions, samples can be measured between -269 °C and 1200 °C.

Additionally detailed analysis of the measurement accuracies are made at ZAE Bayern. For verifying the derived measurement uncertainties, comparison measurements are done together with well-established international institutes, such as the National Institute of Standards and Technology (NIST) in Gaithersburg. An intercomparison measurement is depicted in Fig. 2 for a highly reflecting sample and in Fig. 3 for a strongly absorbing sample, together with the expanded measurement uncertainty of ZAE Bayern. It is visible that the resulting values are in very good agreement. Furthermore national round robin tests are performed in cooperation with institutions like the Physikalisch-Technische Bundesanstalt (PTB) in Berlin.

The experimental equipment and metrological expertise located at ZAE Bayern allows the characterization and development of novel and innovative materials, components and systems with optimized infrared-optical properties. The usage of infrared opacifiers for example leads to a significant reduction of the radiative thermal conductivity of insulation materials. Even at ambient temperature radiative heat transfer yields a substantial contribution to the total heat transfer through a sample. As another example, the development of a transparent low-e coating (Fig. 4) needs to be accompanied by infrared-optical characterizations for evaluating the research progress and for quantifying the resulting properties.


Fig. 1: Integrating sphere with infrared-detector.


Fig. 2: Reflectance of a diffuse gold mirror.


Fig. 3: Reflectance of a carbon aerogel.


Fig. 4: Transparent low-e coatings based on indium tin oxide (ITO) which has been developed at ZAE Bayern and which is processed by sol-gel-technique.


For more information please contact:

Dr. Hans-Peter Ebert
Head of Division: Functional Materials for Energy Technology
Bavarian Center for Applied Energy Research (ZAE Bayern)
Am Hubland, 97074 Würzburg, Germany
Phone: +49 931/ 705 64-34
Fax:    +49 931/ 705 64-60


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