Berlin 2005 – wissenschaftliches Programm

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AKFH: Fachhochschulen

AKFH 1: Postersitzung: Forschung an Fachhochschulen

AKFH 1.11: Poster

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

Challenges in infrared imaging: low emissivities of hot gases, metals, and metallic cavities — •Michael Vollmer, Frank Pinno, Detlef Karstädt, Steffen Henke, and Klaus-Peter Möllmann — FH Brandenburg

In infrared thermal imaging, the temperatures are computed from the measured IR radiation according to Plancks law, modified by corrections due to the camera (detector response, transmission of optics etc.) as well as to the emitter, i.e. the object under consideration. The major problems in quantitatively interpreting surface temperatures from objects are due to the latter correction, which is described by the emissivity є of the objects. Its value is an input parameter, adjustable at the camera and in the analysis software and requires additional knowledge of the system under study. For most objects, emissivities are assumed to be constant (grey bodies) with values ranging well above 0.8. In this case, slight variations in the chosen є-value lead only to minor changes of the resulting surface temperatures. The present work deals with two different systems with low emissivities. First hot gases are studied which, depending on the optical depth, may have є-values well below 0.01. Second, polished metals are important in practical work. Using the same specimen, є-changes occur when shifting from SW to LW camera systems. In order to better deal with the respective low emissivities, metallic cavities were studied with є-values in the range of 0.3 to 0.6.