Spatiotemporally Resolved Light Propagation in Transparent Wood

Abstract Transparent wood biocomposite (TW) is a sustainable optical material that combines high transmittance with mechanical strength but also exhibits pronounced haze. This haze limits applications where high optical transparency is required, and its physical origin remains insufficiently understood. In this study, photon transport in TW and related wood‐based scaffolds at different stages of chemical modification, including delignified wood (DW), native wood (NW) and bleached wood (BW) templates is investigated. Time‐ and space‐resolved transmission measurements are used to extract direction‐dependent scattering and absorption coefficients. DW, BW, and NW samples exhibit anisotropic light propagation while TW both suppresses scattering and alters the scattering anisotropy, flipping 90° the dominant transport orientation relative to the fibers. Extracted optical parameters confirm low scattering coefficients, up to 2 orders of magnitude lower than the NW, BW, or DW. The main scattering mechanism for TW is identified as in‐plane refraction, leading to predominant forward transmission or “snake‐like” photon trajectories, marking a transition from diffusive to quasi‐ballistic transport. These insights advance the fundamental understanding of light transport in hierarchical biocomposites and offer a framework for designing sustainable optical composites with broad haze control, increasing the functional potential of TW toward “wood glass”.