3D Monte Carlo time-of-flight photon propagation modeling

Tetrahedral meshes were generated via Delaunay triangulation using the MATLAB based program Iso2mesh that calls cgalmesh³³. Meshing was performed with different mesh properties varying maximal tetrahedral element volume and Delaunay sphere size in order to optimize simulation efficiency. Settings were optimized for a Delaunay sphere of 1 (10 µm) and a tetrahedral element volume of 5 (50 µm). Generated tetrahedral meshes were used as source architecture for a mesh-based 3D Monte-Carlo light transport simulation (mmclab)³⁴. The model uses the generated tetrahedral mesh and calculates photon propagation based on the inherent optical parameters, the absorption coefficient µ_a [mm⁻¹], the scattering coefficient µ_s [mm⁻¹], the anisotropy of scattering g [dimensionless] and the refractive index n [dimensionless]³⁵. The optical parameters were extracted via integrating sphere measurements (see above) and were used to calculate time-of-flight photon propagation in the bionic coral. The probe illumination was a collimated point source with varying source positions.