CRACK IMAGING BY SCANNING LASER LINE THERMOGRAPHY

3D finite difference modeling results showing the sensitivity of laser line thermography to cracks of varying lengths, depths and openings are presented. A novel crack imaging technique based on assembling second spatial derivative thermal images of a scanned laser line is presented. Experimental results show the technique to image cracks with openings of a few micrometres. The technique is found to have an imaging rate twenty times higher than that of scanning laser spot thermography.