Optical characterization of wood properties using the tracheid effect

Wood, with its exceptional characteristics of lightness and strength, presents notable technical possibilities in industry, as well as serving as a significant carbon sink for society. Nonetheless, the natural diversity of wood species, particularly in temperate areas, poses a challenge when attempting to assess associated mechanical properties and to anticipate widespread application in mass markets. The wood manufacturing community is therefore seeking to establish rapid and automated techniques to determine the characteristics of French wood species, focusing on wood of all grades. One such technique which has received much recent interest is based on the "tracheid effect" which provides information on the local orientation of wood fibres. However, this approach is not universally applicable to all types of wood, and the factors that impact the tracheid effect are still relatively understudied, relying on scattering models using Monte-Carlo simulations. ZEMAX OpticStudio@ANSYS (ZOS), a powerful optical design software suite, has a non-sequential module similar to Monte Carlo approaches and includes a CAD module for modelling complex structures. This presentation shows how the use of this software improves our understanding of the phenomena involved in the tracheid effect, and can enable a more thorough characterization of wood fibre orientations. We compare our models with experimental data from common wood species. In this way, we hope to improve the measurement of wood properties and optimize the use of secondary-grade wood in sectors such as construction, furniture and packaging.