Direct determination of the refractive index of natural multilayer systems
Direct determination of the refractive index of natural multilayer systems
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DOI：
10.1103/physreve.83.051917
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发表时间：
2011-05-18
影响因子：
2.4
通讯作者：
Kinoshita, Shuichi
中科院分区：
文献类型：
--
作者：
Yoshioka, Shinya;Kinoshita, Shuichi
众所周知，在某些甲虫鞘翅中观察到的类金属强反射是由多层薄膜干涉产生的。为了定量分析这些鞘翅中的结构色，有必要知道组成多层结构的材料的折射率的准确值。然而，折射率的确定并不是一件容易的事：鞘膜表面不是平坦的，而是弯曲的，通常包含许多不规则的凸起，这会导致散射损失。这些结构特征使我们无法直接应用传统的光学技术来确定折射率，例如椭圆偏振法，因为这些技术需要完美的镜面。在本文中，我们报告了一个新的实验程序，可以直接确定自然多层膜系统中的各个层的折射率。这一程序包括半额薄切片的样品和随后的光学检查使用显微分光光度计。我们证明，复折射率及其波长依赖性可以成功地确定一种甲虫。
It is well known that the metal-like strong reflection observed in the elytra of some kinds of beetles is produced by multilayer thin-film interference. For the quantitative analyses of the structural colors in these elytra, it is necessary to know accurate values of the refractive indices of the materials that comprise the multilayer structure. However, index determination is not an easy task: The elytron surface is not flat but curved and usually contains many irregular bumps, which cause scattering loss. These structural characteristics prevent us from directly applying conventional optical techniques for index determination, such as ellipsometry, since these techniques require a perfectly specular surface. In this paper, we report a new experimental procedure that can directly determine the refractive indices of individual layers in natural multilayer systems. This procedure involves semi-frontal thin-sectioning of the sample and subsequent optical examinations using a microspectrophotometer. We demonstrate that the complex refractive index and its wavelength dependence can be successfully determined for one kind of beetle.