Interferometric analysis of ultrashort pulse laser-induced pressure waves in water

Pressure waves generated by the surface ablation of water with ultrashort laser pulses in the 140 fs–10 ps duration range were studied with a Mach–Zehnder interferometry. Formation and propagation of spherical and, in ablation with longer pulses, combination of spherical and cylindrical pressure waves were observed. Measurements of the amplitude and dynamics of the pressure waves show that the conversion efficiency of laser energy to mechanical energy of the pressure waves is less than 1%, thus justifying the claim that ultrashort laser pulse ablation induces low-collateral damage and has a large potential in biomedical applications.