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 Test systems for Optical excited Lockin Thermography (OLT) Basic idea of the Lockin-Thermografie is the imaging detection of the phases lag of a thermal wave. The phases angle provides information over thermal structures, inhomogeneities and defects in a component. Intensity modulated halogene lamps are used to generate the thermal wave, heating the inspected object with low intensity in a remote and non-destructive way. Large measurement area, low heating-up To detect the so induced thermal wave, a high resolution infrared camera is used. By using Lockin-analysis the time shift of the thermal wave at the stimulation-frequency is analysed. Interferences as well as disturbing heat-sources or gradients through inhomogene illumination are suppressed. The signal-to-noise-ratio is very good. 
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