Crack Detection by Laser Spot Imaging Thermography

A surface crack, close to a laser heated spot, impedes lateral heat flow and produces alterations in the shape of the laser spot image that can be monitored by thermography. The technique has been found to be successful for determining the location of fatigue cracks. Results are presented that have been obtained using long pulse heating and by flying spot scanning a pulsed laser beam. The results are compared with a preliminary 2D numerical model.