Elastic wave burst thermography for NDE of subsurface features

Mechanical defects are imperfections that have a different behaviour in ter ms of local stiffness or losses due to friction or hysteresis, Measurement techniques responding to such properties map be used to reveal defects sele ctivety. Ultrasound lock-in thermography, described previously, is such a m ethod upon which the technique is based that is described in this paper: Th e advantage of burst excitation with subsequent Fourier transformation is t hat more complete information is provided in a shorter time, while the adva ntage of phase angle imaging - insensitivity to optical and infrared featur es - is preserved.