A new laser ultrasonic sensor for testing samples' thickness is developed. This sensor has high-frequency response and high sensitivity. Furthermore it is easy to adjust. When the sensor is used to focus on polished iron plate, well-defined longitude-wave and its echo waves can be obtained. Based on the experimental results, the sample’s thickness can be deduced. The theoretical and experimental results are in good agreement with relative error of 0.5%.
Based on the optical beam deflection (OBD) technique, a fiber-optic diagnostic technique is applied to investigate the pulsation of a laser-induced cavitation bubble on the vicinity of an aluminum target in water. The sequence waveforms induced by the bubble pulsation is presented and analyzed in detail. The maximum radii corresponding to each pulsation are determined. Furthermore, by varying the acting laser energy, the variation of the maximum bubble radius and bubble energy with respect to acting laser energy is obtained. The theoretical and experimental results are in good agreement within a relative error.