Influence of initial time of laser ultrasonic on calculating its propagation velocity in a diamond anvil cell

Sound velocity is important to study the elastic behaviors of materials in high pressure physics and the accuracy acquisition of travel time for velocity calculation is very essential. Thermoelastic finite element models of ultrasonic displacement field induced by a subnanosecond pulsed laser in metal films with a diamond anvil cell are established and the processes of laser ultrasonic generation are analyzed in detail. By confirming the initial time, we improved the accuracy of calculating the longitudinal wave velocity in the aluminum and copper thin films. The formulas of delay time are obtained by a set of simulations, and the overall errors of modified longitudinal velocity are reduced by 10–60 times of the unmodified ones.

► The processes of laser ultrasonic generation in DAC are simulated by the FEM.
► The reaction force deduced by diamond enhances longitudinal wave generation.
► Modified initial time by deducting delay time increases calculation precision.
► The delay of initial time increases with laser duration and relates to material.