Allen W A, Gausman H W, Richardson A J
Appl Opt. 1973 Oct 1;12(10):2448-53. doi: 10.1364/AO.12.002448.
The widely accepted Willstätter-Stoll (W-S) theory of leaf reflectance has been investigated by extensive ray tracing through a model (W-S model) in which the leaf cellular structure is approximated by circular arcs. Calculations were performed on an IBM 1800 computer. The W-S model is treated as a two-dimensional, uncentered optical system consisting of a single medium and air. Optical properties of the medium are specified by a complex index of refraction. Given an incident ray, new reflected and transmitted rays are produced at each interface with properties determined by the laws of Snell, Fresnel, and Lambert. Calculations indicate that the W-S model, as exemplified by their artist's conception, is too transparent, that is, the magnitude predicted for transmittance is too high. Transmittance is still too high if each interface is treated as a diffusive instead of a smooth surface. The W-S model can be easily improved, however, by introduction of more intercellular air spaces. The modified W-S model promises to be an excellent representation of physical reality. Accurate predictions, however, require an inordinate amount of computer time.
被广泛接受的威尔施泰特 - 斯托尔（W - S）叶片反射理论，已通过在一个模型（W - S模型）中进行广泛的光线追踪进行了研究，在该模型中叶片细胞结构由圆弧近似表示。计算是在IBM 1800计算机上进行的。W - S模型被视为一个由单一介质和空气组成的二维、非中心光学系统。介质的光学特性由复折射率指定。给定一条入射光线，在每个界面都会产生新的反射光线和透射光线，其特性由斯涅尔定律、菲涅尔定律和朗伯定律确定。计算表明，如艺术家概念图所示的W - S模型过于透明，也就是说，预测的透射率大小过高。如果将每个界面视为漫射面而非光滑面，透射率仍然过高。然而，通过引入更多细胞间气隙，W - S模型可以很容易地得到改进。改进后的W - S模型有望很好地反映物理现实。然而，准确的预测需要大量的计算机时间。
