Nondestructive testing with thermal waves using phase-shifted temporal speckle pattern interferometry

Abstract

A temporally modulated IR lamp is employed to heat the sur- face of a flawed plate and the resulting out-of-plane thermoelastic de- flection is monitored using phase-shifted temporal speckle pattern inter- ferometry. The speckle interferograms are continuously recorded by means of a high-speed digital camera with temporal phase shifting car- ried out by a Pockels cell synchronized with it. Temporal phase unwrap- ping through sequences of several hundreds of frames enables the de- termination of time-varying absolute displacement maps. Experimental results illustrate the possibilities of this novel nondestructive testing tech- nique. © 2003 Society of Photo-Optical Instrumentation Engineers.