Berlin 2005 – wissenschaftliches Programm

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AKFH: Fachhochschulen

AKFH 1: Postersitzung: Forschung an Fachhochschulen

AKFH 1.10: Poster

Freitag, 4. März 2005, 14:00–15:30, Poster TU C

Identification and suppression of thermal reflections in infrared thermal imaging — •Michael Vollmer, Klaus-Peter Moellmann, Detlef Karstaedt, Frank Pinno, and Steffen Henke — FH Brandenburg

Thermal reflections are a common source of problems in interpreting IR thermal images. In particular atomically smooth surfaces like glass, metals or wet surfaces, but also brick and concrete may easily give rise to reflections of infrared radiation from often uncared sources. These may, e.g., be due to people or other infrared sources in the vicinity of objects under consideration. If unnoticed, they may give rise to misinterpretations of the object temperature. Such reflections often go unnoticed since some surfaces are not yet good mirrors in the visible, whereas they are very good reflecting surfaces in the IR spectral range. Obviously, it is desirable to suppress or at least identify thermal reflections in order to account for them in the thermal image analysis. In order to achieve this, we studied the use of polarizers of thermal infrared radiation for short and long wave camera systems. The principle idea behind is the same as suppression of reflections in visible photography: we apply Fresnel formulas to suppress the radiation, polarized perpendicular to the plane of incidence. We discuss the specific problems and changes of the method in comparison to the technique in the visible spectral range and demonstrate for a variety of materials, that this technqiue is sometimes useful to strongly suppress thermal reflections. In all other cases, it offers an easy means to identify such reflections.