Research on quantitative evaluation of infrared thermography

In the paper, quantitative evaluation of infrared thermography is studied. Based on the heat conduction model, the relation between defect depth and time is analyzed. The concepts of initial separation time point and maximum contrast changing time point are given and their relationship with defect depth is built. Comparison with maximum contrast time point is made. The influence of defect size, external heat stimulation intensity and duration on acquired defect depth is analyzed. The changing rule of defect size is found and the best measurement time region is given. In addition, the time points of the start and end of stimulation are determined by averaging the intensity of image sequences, which sets up the base origination time point for the evaluation of defect depth.