LED optical excitation for the long pulse and lock-in thermographic techniques
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TLDR
In this article, high power light emitting diode (LED) arrays have been investigated as excitation sources for long pulse and lock-in thermography, and they were found to emit some IR radiation, although far less than conventional incandescent light sources.Abstract:
High power light emitting diode (LED) arrays have been investigated as excitation sources for long pulse and lock-in thermography. Images of artificial defects in a carbon fibre reinforced plastic (CFRP) composite sample are compared, by image contrast signal-to-noise ratio estimates, with those obtained using conventional incandescent flash and lock-in excitation sources. The LED arrays had to be mounted on heat sinks with active cooling in to prevent them exceeding their thermal tolerance. Despite this cooling the LED arrays were still found to emit some IR radiation, although far less than conventional incandescent light sources.read more
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References
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Thermal wave imaging with phase sensitive modulated thermography
TL;DR: In this paper, the authors combined thermal wave and thermography to provide a short-time low-frequency phase angle image where non-thermal features can be suppressed using lock-in data analysis.
Journal ArticleDOI
Optoacoustic phase angle measurement for probing a metal
TL;DR: In this paper, it is shown that using optoacoustic phase angle scanning rather than amplitude scanning enables precise measurements of subsurface structure in metal, for some applications the method can be an alternative to x-ray imaging.
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Advances in pulsed thermography
TL;DR: In this article, the authors developed an alternative approach to analysis of pulsed thermographic data, based on developing a parametric equation for the time history of each pixel, which provides increased spatial and temporal resolution, and significantly extends the range of defect depths and sample configurations.
Journal ArticleDOI
Matched excitation energy comparison of the pulse and lock-in thermography NDE techniques
TL;DR: In this article, the defect detection capabilities of pulse transient thermography and lock-in thermography were compared using equal excitation energies, and a signal-to-noise ratio analysis was performed on defect images obtained by the two techniques.
Journal ArticleDOI
Evaluation of defects in composite plates under convective environments using lock-in thermography
TL;DR: In this paper, a photothermal model is developed in order to investigate the behavior of thermal waves in homogeneous plates and layered plates with finite thicknesses under convective conditions, and the model is then utilized to predict the phase differences produced by multi-layer subsurface defects and optimum inspection parameters.