Year: 2026
Type: preprint
Abstract: Transparent wood (TW) composites possess residual haze that limits image clarity despite their high light transmission, yet the physical origin of this scattering has not been established. Here, polarization-resolved measurements reveal a pronounced polarization dependence of scattering by a wood-polymer composite with improved refractive index matching. Polarization- and spectrally-resolved haze as low as 21% (40-45% at 550 nm for unpolarized light) with transmittance of approximately 92% for polarization perpendicular to the fibers was detected. It is found that the low-haze spectrum closely follows an inverse-square relation over the 400-800 nm range, well described by a weak-index-contrast Rayleigh-Gans-Debye (RGD) model invoking subwavelength birefringent heterogeneities within the cell wall. This physical mechanism was previously obscured by haze-limiting strong scattering from debonding gaps or refraction at the lumen-cell wall interface. Scanning electron diffraction independently reveals spatially distinct domains with markedly different cellulose diffraction responses within the infiltrated cell walls. The observed polarization-dependent refractive-index mismatch is attributed to inherent cellulose birefringence. Time-resolved measurements further support nearly scattering-free quasi-ballistic transport of the sampled transmitted light. It is demonstrated that selecting only a preferential polarization markedly improves image visibility through TW without further material modification. These findings connect polarization-dependent haze to the internal structure of transparent wood and identify ways to engineer a refractive-index match in hierarchical anisotropic composites towards glass-like clarity.
Source: arXiv (Cornell University)
Language: English
Subfield: Biomaterials
Field: Materials Science
Domain: Physical Sciences
Open Access status: green
OpenAlex ID: W7223955110