Fig. 1. Time-resolved transmittance T(t) through a nonabsorbing 1 mm-thick scattering slab for two refractive index contrast values n=1,1.2. Solid curves represent isotropic simulations with μs,iso=10mm−1. For each case, a predefined ratio between scattering coefficients along different axes is imposed, as specified in the title above each column. Anisotropic configurations exhibiting the same decay rate as the isotropic case are shown, leading to values of μs,z≠μs,iso. All simulations are performed setting g=0.

Fig. 2. (a) Sketch of the experimental setup for time-resolved measurements when using a 1525 nm probing wavelength. Ti:Sa, titanium sapphire fs laser; OPO, optical parametric oscillator; BBO, β-barium borate nonlinear crystal; CCD, charge-coupled device camera; PMT, photomultiplier tube. (b) Schematics of the transient imaging measurement on a slab sample. The instantaneous spatial distribution of transmitted intensity is imaged at different time delays. (c) Photograph of the paper Post-it note (left) and PTFE tape strip (right) with corresponding scanning electron microscope images of the two samples (insets). Scale bars correspond to 100 and 30μm for paper and PTFE tape, respectively.

Fig. 3. Selection of transient imaging measurements (top) and corresponding best-fit MC simulations (bottom) of the transmitted intensity distribution recorded at different times for the PTFE tape sample probed at 1525 nm. Each frame shows an area of 7.4mm×7.4mm and is normalized to its maximum intensity value. The time delay between consecutive frames is Δt=1.33ps.

Fig. 4. (a) MSD and (b) time-resolved transmitted intensity of PTFE tape. Solid lines represent the best-fit anisotropic MC simulations, obtained with μs,x=48mm−1, μs,y=105mm−1, μs,z=77mm−1, g=0.9, and μa=0. The dashed purple curve shows a fit performed with an isotropic MC simulation with μs,iso=95mm−1. Shaded areas represent (a) the compounded uncertainty from the pixel-to-micrometer conversion and the bivariate Gaussian fit and (b) 1σ of the average between five different sample positions, respectively.

Fig. 5. Selection of transient imaging measurements (top) and corresponding best-fit MC simulations (bottom) of the transmitted intensity distribution recorded at different times for the Post-it note performed at 820 nm probing wavelength. Each frame shows an area of 2.7mm×2.7mm and is normalized to its maximum value. The time delay between consecutive frames is Δt=1ps.

Fig. 6. (a) MSD and (b) time-resolved transmitted intensity of paper. Solid lines represent the best-fit anisotropic MC simulations, obtained with μs,x=223mm−1, μs,y=148mm−1, μs,z=343mm−1, g=0.8, and μa=0.015mm−1. The dashed purple curve shows a fit performed with an isotropic MC simulation with μs,iso=455mm−1. Shaded areas represent (a) the compounded uncertainty from the pixel-to-micrometer conversion and the bivariate Gaussian fit and (b) 1σ of the average between six different sample positions, respectively.