Applications of Laser-Based Ultrasonic Testing Technique on Nondestructive Testing and Structure Health Monitoring

Abstract

This paper introduces the laser-based ultrasonic technique and its application in the fields of nondestructive testing (NDT) and structure health monitoring. A Q-switched Nd:YAG laser with wavelength of 1064nm and pulse duration of 10 ns was used to generate ultrasound including bulk wave and Rayleigh wave. For the various purposes in practical engineering, electromagnetic acoustic transducer (EMAT), laser interferometer and fiber Bragg grating (FBG) sensing system were employed as employed as discrete sensing elements to detect the ultrasonic generated by pulsed laser. These detector systems had their own advantage and range of frequency responses which decide to their application fields. Conventional piezoelectric transducer (PZT) was also used in the experiments to compare with the laser-ultrasonic testing results.