Goodling Amy E, Nagelberg Sara, Kaehr Bryan, Meredith Caleb H, Cheon Seong Ik, Saunders Ashley P, Kolle Mathias, Zarzar Lauren D
Department of Materials Science and Engineering, The Pennsylvania State University, University Park, PA, USA.
Department of Mechanical Engineering, Massachusetts Institute of Technology, Cambridge, MA, USA.
Nature. 2019 Feb;566(7745):523-527. doi: 10.1038/s41586-019-0946-4. Epub 2019 Feb 27.
Many physical phenomena create colour: spectrally selective light absorption by pigments and dyes, material-specific optical dispersion and light interference in micrometre-scale and nanometre-scale periodic structures. In addition, scattering, diffraction and interference mechanisms are inherent to spherical droplets, which contribute to atmospheric phenomena such as glories, coronas and rainbows. Here we describe a previously unrecognized mechanism for creating iridescent structural colour with large angular spectral separation. Light travelling along different trajectories of total internal reflection at a concave optical interface can interfere to generate brilliant patterns of colour. The effect is generated at interfaces with dimensions that are orders of magnitude larger than the wavelength of visible light and is readily observed in systems as simple as water drops condensed on a transparent substrate. We also exploit this phenomenon in complex systems, including multiphase droplets, three-dimensional patterned polymer surfaces and solid microparticles, to create patterns of iridescent colour that are consistent with theoretical predictions. Such controllable structural colouration is straightforward to generate at microscale interfaces, so we expect that the design principles and predictive theory outlined here will be of interest both for fundamental exploration in optics and for application in functional colloidal inks and paints, displays and sensors.
颜料和染料的光谱选择性光吸收、特定材料的光学色散以及微米级和纳米级周期性结构中的光干涉。此外，散射、衍射和干涉机制是球形液滴所固有的，它们会导致诸如宝光环、日冕和彩虹等大气现象。在此，我们描述了一种用于产生具有大角度光谱分离的彩虹色结构色的前所未有的机制。在凹面光学界面处沿不同全内反射轨迹传播的光会相互干涉，从而产生绚丽的色彩图案。这种效应在尺寸比可见光波长大数倍的界面处产生，并且在诸如凝结在透明基板上的水滴这样简单的系统中很容易观察到。我们还在包括多相液滴、三维图案化聚合物表面和固体微粒在内的复杂系统中利用这一现象，以产生与理论预测相符的彩虹色图案。这种可控的结构色在微观界面处很容易产生，因此我们预计这里概述的设计原理和预测理论将对光学的基础探索以及功能性胶体油墨和涂料、显示器及传感器的应用都具有吸引力。
