Fig. 4.

(d)–(f) Experimental study of mechanical wave propagation in a layer of PVA phantom (mimicking soft tissue) bounded with water on the bottom (see Fig. 2) is compared to numerical simulations in (a)–(c) OnScale for the same medium parameters. The dimensionless signal bandwidth $BW*\frac{h}{C_s}=0.5$ (maximum achievable in the experiment). Spatial and temporal parameters of the push are $d\cong 500\mu \mathrm{m}$ and $T=100\mu \mathrm{s}$, respectively; the elastic modulus measured for a thick phantom is $\mu =14.44\mathrm{kPa}$ (shear wave speed $C_s=3.8\mathrm{m}/\mathrm{s}$). The layer thickness was measured from the OCT structural image [Fig. 2(b)] to be $h\cong 0.5\mathrm{mm}$. (a) An XT plot (wave field) calculated along the phantom surface. (b) The phase velocity dispersion computed from the wave field of (a) red crosses, superimposed on the analytical solution⁵ (solid lines), respectively. (c), (f) 2-D group velocity images normalized to the true shear wave speed (i.e., displayed value is 1 for a group velocity estimate equaling the true shear wave velocity) obtained for every point of the $XZ$ plane with the correlation method.