China
Africa
Explore chapters and articles related to this topic
Waves and electromagnetic radiation
Published in Andrew Norton, Dynamic Fields and Waves, 2019
The coloration of a Morpho rhetenor butterfly’s wing is caused by interference between light reflected from several layers of transparent material in tiny fern-like structures above the wing, as shown in Figure 2.83a. The layers are about 60 nm thick and are separated by about 130nm. Light is reflected at both surfaces of each layer, and the superposition of the reflected waves leads to interference effects, and hence to bright iridescence at certain wavelengths. It turns out that the superposition of waves from the top and bottom of any one layer gives constructive interference for wavelengths in the ultraviolet rather than the visible part of the electromagnetic spectrum: reflections between waves from one layer and the next are the most likely candidates for the observed effects in the visible spectrum.
Spatial and Spectral Filters
Published in Daniel Malacara-Hernández, Brian J. Thompson, Advanced Optical Instruments and Techniques, 2017
One of the advantages of decorative coatings that depend on interference is their variation with angle of incidence, known as iridescence. Unfortunately the high-index layer in the above configuration inhibits the variation. A low index layer is much better in this application. To use a low-index layer it is necessary to enhance the outer reflectance, typically by adding a thin metal layer, usually chromium. Since the index of the layer is no longer limitation, a high performance metal like aluminum can now be used as the base giving still higher brightness for the resulting color. Such coatings are often deposited on the base of a decorative prism, which then shows large color variations with angle of incidence. A magenta color at normal incidence changing to green at oblique incidence is a popular arrangement.
MIRASOL Displays
Published in Laurent A. Francis, Krzysztof Iniewski, Novel Advances in Microsystems Technologies and Their Applications, 2017
Rashmi Rao, Jennifer Gille, Nassim Khonsari
Colouration in nature is generally realized in one of two ways: through pigmentation or by iridescence[1,2]. Iridescence (originated from the Greek word ‘irides’ – ‘rainbows’) is an optical phenomenon caused by multiple reflections from multiple layers of optical films in which phase shift and interference of the reflections modulate the incident light by amplifying or attenuating certain wavelengths more than others. Some examples of iridescence in nature include colouring in some butterfly wings, feathers of some birds and seashells [3]. There have been ongoing efforts to leverage and mimic these natural colour generation techniques to apply them to man-made devices. Recent developments in micro- and nanofabrication and photonics allow the fabrication of structures that mimic iridescent properties found in nature by manipulating light in a controlled manner via the use of MEMS/nanoelectromechanical systems (NEMS) architectures. These developments make a variety of novel devices and applications possible [4–6], including Qualcomm’s reflective mirasol display [7–10].
Influence of chiral monomer concentration on thermo-optical properties of glass-forming cyclic siloxane side chain liquid crystal oligomers
Published in Liquid Crystals, 2022
Congcong Luo, Bing Yao, Xihua Du, Yan Chen, Jun Zhou, Shijie Li, Haitao Liu, Jiwei Wang, Aikebaier Reheman
Thus, the cyclosiloxane LC oligomers contained an achiral monomer with benzene methyl ester groups and a chiral (-)-menthyl monomer, with the chirality characteristic and the easy achievement of glassy state were prepared in this paper. On the glassy state, these oligomers show typical iridescent colours from green to red simply tuned by the concentration of chiral (-)-menthyl monomer in the oligomers. These oligomers can be easily quenched in liquid nitrogen at room temperature and their colours were permanently stored. Due to the helical arrangement of molecules, the chiral cyclic LCs exhibits the unique optical properties of selective reflection of light. When the reflected wavelength is in the range of the visible spectrum, an iridescent colour can be observed. So, in this paper, a series of cyclic side chain LC oligomers with different chiral monomer concentration were synthesised by typical hydrosilylation of cyclotetrasiloxane with vinyl derivatives (Figure 1(a,b)). The schematic illustration of the selective reflection colours and pitch of oligomers at N* phase by thermal quenching treatment when irradiating by white light are shown in Figure 1(c).
Structural coloration and its application to textiles: a review
Published in The Journal of The Textile Institute, 2020
Meilin Huang, Sheng-Guo Lu, Yongcong Ren, Jingpeng Liang, Xueying Lin, Xiaoru Wang
There are four principal mechanisms associated with structural coloration. First of all, structural color can be generated through thin-film interference with an iridescent effect where the colors alter according to changes in the angle of sunlight or vision. This incorporates monolayer and multilayer thin-film interference, such as the surface color of a soap bubble or the organic transparency of the wings of dragonflies, beetles, etc. Structural color caused by monolayer thin-film interference is rare, but multilayer thin-film interference is relatively common, though structurally complex. Secondly, structural color can be generated by a diffraction grating effect, which incorporates effects such as iridescence. This includes the color of certain crustacean hairs, snake skin, music CDs, etc. Thirdly, the scattering and dispersion of light can produce a structural color without any iridescent effect, e.g. the blue of the sky and the ocean. Fourthly, structural color can be a consequence of the presence of PCs, a natural example of which is opal, by which can also be artificially constructed. There are many organisms and objects with structural colors in nature, which may conform to one or more of the above principles. Some examples are shown in Figure 1.