J. Eur. Opt. Society-Rapid Publ. 2026, 22, 48 Ó The Author( s), published by EDP Sciences, 2026 https:// doi. org / 10.1051 / jeos / 2026044 Available online at: https:// jeos. edpsciences. org
Journal of the European Optical Society-Rapid Publications
RESEARCH ARTICLE
Impact of skin pores on photon transport in near – infrared optical tissue imaging
Serhat Ilgaz Yöner 1, * and Mehmet Emin Aksoy 1, 2
1 Department of Biomedical Device Technology, Vocational School, Acibadem Mehmet Ali Aydinlar University, Istanbul 34752, Türkiye 2 CASE( Center of Advanced Simulation and Education), Acibadem Mehmet Ali Aydinlar University, Istanbul 34752, Türkiye
Received 28 January 2026 / Accepted 7 May 2026
Abstract. Near-infrared optical tissue imaging is sensitive to both the optical properties of biological media and their microstructural geometry. While macroscopic tissue characteristics are well studied, the quantitative impact of skin pores on photon propagation remains largely unexplored. Here, we investigate this influence using a cascaded computational framework. Anatomically realistic tissue geometries were reconstructed from segmented MRI data of eight cadaveric heads, consisting scalp, skull, cerebrospinal fluid, and brain layers. Ballistic photon propagation simulations first resolved geometric optical interactions at the skin surface with explicit pore microgeometry, and the resulting photon states initialized Monte Carlo-based diffusive photon transport simulations to produce voxel-wise fluence maps and depth-resolved sensitivity analysis. Results indicate that skin pores increase photon angular divergence during the ballistic phase, but these directional perturbations are rapidly randomized by multiple scattering and do not measurably alter depth sensitivity( DS) profiles or photon path statistics. In contrast, pore-induced reductions in photon weight persist, decreasing the photon budget available for deeper tissue transport. These results indicate that surface microgeometry primarily affects optical coupling efficiency rather than stochastic photon propagation, providing guidance for when pore-scale features can be neglected or should be explicitly incorporated in biomedical optical system design.
Keywords: Skin pore, Photon propagation, Optical tissue imaging, Photon – tissue interaction.
1 Introduction
Near – infrared( NIR) optical tissue imaging is widely used to probe subsurface structures and optical contrast in biological media [ 1 – 3 ], owing to the relatively low absorption and moderate scattering of tissue in this spectral window [ 4 – 6 ]. Accurate interpretation of measured signals depends critically on reliable forward models of photon transport through layered tissue structures [ 7 – 10 ]. Photon propagation in the human head is governed by a complex interplay between tissue optical properties, anatomical geometry, and refractive index mismatches at tissue boundaries [ 11, 12 ]. While the influence of bulk tissue composition and macroscopic anatomical variability has been extensively studied [ 13 ], the role of fine – scale surface microgeometry in shaping photon transport remains incompletely understood.
The outermost boundary of the tissue domain, corresponding to the scalp surface, is characterized by pronounced microstructural features, most notably skin pores
* Corresponding author. ilgazyoner @ gmail. com
[ 14, 15 ]. Such structures introduce localized geometric perturbations and refractive index discontinuities at medium interfaces [ 9, 16 ], potentially modifying photon coupling conditions and the angular distribution of injected light. In practice, surface microstructural features such as skin pores are almost universally ignored in the design and modeling of NIR optical imaging systems, where tissue boundaries are treated as smooth planar or gently curved interfaces. This design choice is commonly motivated by the expectation that scattering within superficial tissue layers rapidly randomizes photon trajectories [ 17 – 20 ], effectively suppressing sensitivity to small – scale surface irregularities. From a ray – based propagation perspective, pore – scale structures are similarly assumed to act as weak perturbations relative to the optical source footprint and emission divergence, and are therefore not expected to produce sustained alterations in photon trajectories or coupling efficiency. Accordingly, smooth boundary assumptions are generally considered adequate for predicting optical coupling and power transmission at the tissue surface. However, the validity of these assumptions has not been
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