Frequency domain and wavelet analysis of the laser-induced plasma shock waves

•We report acoustical waveform, and acoustical spectroscopy measurements and analysis in a laser-induced plasma of a different metals in air.•Both piezo and microphone transducer were used.•The acoustical spectra of the emission were obtained when the sample (and plasma) were enclosed in experimental chamber.•The acquired acoustical spectra are time-integrated and the frequency peaks were sharp and relatively isolated.•Finally, both time and frequency resolved wavelet spectrogram present a novel method of observing laser-induced plasma behavior.

In addition to optical emission, another trace of interest that laser-induced plasma provides is a form of acoustic feedback. The acoustic emission (AE) signals were obtained using both microphone and piezo transducers. This kind of optoacoustic signals have some distinct features resembling the short, burst-like sounds, that may differ significantly depending mainly on the sample exposed and irradiance applied. Experiments were performed on atmospheric pressure by irradiating various metallic samples. The recorded waveforms were examined and numerically processed. Single-shot acoustical spectra have shown significant potential of providing valuable supplementary information regarding plasma propagation dynamics. Moreover, the general approach suggests the possibility of making the whole measurement system cost-effective and portable.