Figure 2

Primary cavitation stages. Ultrafast dynamics in the process of bubble formation in water in case of short (ps) Bessel pulse irradiation. A moderate focusing geometry is used (θ = 9°) for a 7.4 μJ incident pulse of 3 ps duration. (a) Time-resolved OTM _UFD on ps timescale, showing a gradual absorption-like response resulting from the superposition of the scattering and absorption signatures of a long-living electron plasma and the onset of cavity formation with sub-μm sections. (b) Time-resolved PCM _UFD on ps timescale showing a gradual negative index change response resulting from the superposition of the free carriers and rarefaction signatures. The 17.5 ns observation delay time was chosen to show the development of the emerging pressure wave with an abundance of details in the PCM mode. The white domain preceding the pressure wave may be associated with a halo inherent to Zernike PCM or to a slight detuning from the Köhler illumination geometry. The slight light color preceding the pulse in OTM _UFD confirms the presence of a leading compression front.