Advances in pulsed thermography

The use of pulsed thermography as an NDE solution for manufacturing and in-service applications has increased dramatically in the past five years, enabled by advances in IR camera and computer technology. However, the basic approaches to analysis and processing of pulsed thermographic data have remained largely unchanged. These methods include image averaging, subtraction, division, slope calculation and contrast methods (e.g. peak contrast and peak slope time mapping). We have developed an alternative approach to analysis of pulsed thermographic data, based on developing a parametric equation for the time history of each pixel(1). The resulting "synthetic" image provides increased spatial and temporal resolution, and significantly extends the range of defect depths and sample configurations to which pulsed thermography can be applied. In addition, our approach reduces the amount of data that must be manipulated and stored, so that an entire array of image sequences from a large structure can be processed simultaneously.