Measurement of three-dimensional distribution of crack tips by low power pulsed laser

A simple measurement technique to evaluate micro cracks in a solid PMMA specimen is studied. Taking advantages of laser induced pulsed waves, and a two-layered transducer composed of PVDF and ceramic transducers, we have tried to obtain three dimensional images of the crack. By using the large amplitudes and low frequency vibration by the PZT transducer, we have obtained interesting images, which seem to show the position of crack tips.