Fig. 2: Holographic phase retrieval and cavitation bubble density.

a X-ray hologram (normalized intensity I/I₀) of a cavitation bubble at Δt = 10 ns, exhibiting strong contrast at the inner interface (gas/shockwave) and outer interface (shockwave/equilibrium water). For phase retrieval, the hologram is averaged along the polar angle to obtain the radial intensity distribution. b Radial intensity distribution of (a) and intensity obtained from numerical propagation of the RFP retrieved phase (see (c)). c In a forward model approach the projected phase \(\overline{\phi }\) of the bubble is retrieved by minimizing the difference to the radial intensity distribution (Radially Fitted Phase, RFP). d Retrieved phase of (a) using the AP algorithm, for comparison. The phase distribution reflects the deficit density in the core and excess density in the shockwave. e The average along the polar angle of the AP reconstruction is compared to the result obtained from RFP (c). f Radial three dimensional phase ϕ reconstructed from the RFP projected phase (c). The right ordinate shows the calculated density distribution of the cavitation bubble for an ellipticity factor ϵ ≈ 0.8. Scale bars: 10 μm (a, d).