Fig. 4.

Plots showing the convergence of the algorithm over 9 iterations for (a) the THz time-of-flight for region A (circles) and region E (triangles). A full line is plotted at t_THz = 15.665 ps and dotted line at t_THz = 6.647 ps showing the convergence value. (b) The depth determined from each iteration of the algorithm for region A (circles) and region E (triangles) with the full line at d₁ = 3.116 mm, and dotted line at d₂ = 1.296 mm. (c) The refractive index from the algorithm after each iteration for n_THz (circles) and n_OCT (triangles), with a full line at n_THz = 1.517 and n_OCT = 1.418 showing convergence.