| Approach: Nondestructive testing with infrared thermography is used to detect and estimate hidden discontinuities within materials. Several inspection techniques based on infrared thermography technology have been developed; for instance pulsed thermography and lockin thermography. These two techniques are basically based on the same principles of diffusion and thermal reflexion, but their approaches differ in the implementation. In lockin thermography, the specimen under investigation is heated up with a modulated light in steady state regime. The periodic wave of light propagates by radiation through the air until it reaches the specimen surface where heat is produced and propagates through the material. Internal defects act as a barrier for heat propagation, which produces changes in the amplitude and phase of the response signal at the surface of the specimen under inspection. |
