Measurement of velocity of Lamb waves excited by laser

The experimental investigation of the dependence of ultrasound pulse parameters of Lamb waves excited by a round shaped optical-thermal emitter on its diameter was carried out. It was found that the ultrasound pulse is divided into two parts when the diameter is 3,0 mm or more. The sources of the separated pulses are considered to be the opposite edges of the optical-thermal emitter. The results show that the dependence of the propagation time of the maximum values for separated pulses on the diameter of the optical-thermal emitter is linear. Thus, the graphical method for the measurement of the group mean velocity of Lamb waves was offered.