3-DIMENSIONAL RADIATION TRANSFER MODELING IN A DICOTYLEDON LEAF

The propagation of light in a typical dicotyledon leaf is investigated with a new Monte Carlo ray-tracing model. The three-dimensional inter nal cellular structure of the various leaf tissues, including the epid ermis, the palisade parenchyma, and the spongy mesophyll, is explicitl y described. Cells of different tissues are assigned appropriate morph ologies and contain realistic amounts of water and chlorophyll. Each c ell constituent is characterized by an index of refraction and an abso rption coefficient. The objective of this study is to investigate how the internal three-dimensional structure of the tissues and the optica l properties of cell constituents control the reflectance and transmit tance of the leaf. Model results compare favorably with laboratory obs ervations. The influence of the roughness of the epidermis on the refl ection and absorption of light is investigated, and simulation results confirm that convex cells in the epidermis focus light on the palisad e parenchyma and increase the absorption of radiation. (C) 1996 Optica l Society of America