Integrated nanosecond laser full-field imaging for femtosecond laser-generated surface acoustic waves in metal film-glass substrate multilayer materials

Abstract

Femtosecond laser pulses are used for the excitation of surface acoustic waves (SAWs) in a gold thin film transducer deposited on a glass substrate, while a single longitudinal nanosecond laser source is employed for their full-field, high-resolution dynamic interferometric imaging in a pump–probe experimental set-up. The successful combination of the two laser sources in one integrated pump–probe set-up, poses no restrictions in the time-delays. The experimental results are supported by numerical simulations implemented by the connection of a finite difference two-temperature model (TTM) with a finite element method (FEM) model. The new integrated method allows for the investigation of the dynamic response of matter for long timescale ranges. Representative applications for SAWs characterization and surface structural defects detection on Au thin metal film deposited on BK7 glass substrate samples, demonstrate the efficiency of the proposed method and the influence of the pulse duration of the excitation pulses.