Computationally effective solution of the inverse problem in time-of-flight spectroscopy

Abstract

Photon time-of-flight (PTOF) spectroscopy enables the estimation of absorption and reduced scattering coefficients of turbid media by measuring the propagation time of short light pulses through turbid medium. The present investigation provides a comparison of the assessed absorption and reduced scattering coefficients from PTOF measurements of intralipid 20% and India ink-based optical phantoms covering a wide range of optical properties relevant for biological tissues and dairy products. Three different models are used to obtain the optical properties by fitting to measured temporal profiles: the Liemert-Kienle model (LKM), the diffusion model (DM) and a white Monte-Carlo (WMC) simulation-based algorithm. For the infinite space geometry, a very good agreement is found between the LKM and WMC, while the results obtained by the DM differ, indicating that the LKM can provide accurate estimation of the optical parameters beyond the limits of the diffusion approximation in a computational effective and accurate manner. This result increases the potential range of applications for PTOF spectroscopy within industrial and biomedical applications.

Accurate and efficient computation of the 3D radiative transfer equation in highly forward-peaked scattering media using a renormalization approach

“…The analytical solution (Eq. (15)) was verified by comparisons with Monte Carlo simulations and experimental data (Kamran et al, 2015 Object for calculation. Figure 3 shows a homogeneous cubic medium with a side of 2.2 cm as an object, in which a source was located near the center of the medium r s = (x s , y s , z s ) = (1.10 cm, 1.10 cm, 0.88 cm), and a detector at…”

Light propagation model of titanium dioxide suspensions in water using the radiative transfer equation

“…where r = |r|, R represents the radius of a large sphere, κ discrete wavenumber, I κ0 (t) the time-dependent mode of the intensity, ξ κ0 the positive root of the equation of j 0 (ξ κ0 R) = 0 with j 0 being the zeroth order spherical Bessel function of the first kind. Independent study [19] has verified the analytical solution (Eq. (10)) by comparing with Monte Carlo simulations and experimental data.…”

“…Meanwhile, in the time-resolved measurements of light, it is not easy to reveive light with a broad wavelength range. However, for the determination of the optical properties, timeresolved measurements have the advantage over the steady-state measurement; the time-resolved measurements allow to determine µ a,λ and µ s,λ separately, while the CW measurements cannot [19]. From the discussion above, this study employs the time-dependent RTE.…”

Broadband Time Domain Diffuse Optical Reflectance Spectroscopy: A Review of Systems, Methods, and Applications

“…where D = 1 3µ s is the diffusion coefficient. The first Equation of (3) is the well-known diffusion equation (DE) and, together with the Fick's Law (second Equation (3)), has been widely used for analytically solving diffusion problems in a variety of geometries, such as: layered laterally infinite media, layered cylinder, sphere, parallelepiped [80][81][82][83][84][85]. The diffusion approximation was shown to work quite well in situations in which the diffusion is higher than the absorption and where the source-detector distance allows the detection of photons having undergone a number of scattering events such that the radiance L becomes almost isotropic [86].…”