Morphological structure and optical properties of the wings of Morphidae

Abstract

The morphological structure and optical properties of the wings of 14 species of Morphidae have been investigated. Most of the scales of the iridescent species of Morphidae (Lepidoptera) present a very particular structure. The ground scales, responsible for the major part of the optical properties, are covered by a very regular set of longitudinal ridges. The ridges themselves are constituted by a superposition of lamellae that act locally as a multilayered structure. This very specific morphology leads to both interferences and diffraction effects. The first one is responsible of the brilliant blue coloration of the males, while the second one diffracts this colored light at a very large angle. These two phenomena give to the butterfly a very effective long‐range communication system. The morphological characteristics of the scales of the various species are presented in detail. Two types of optical measurement were performed on the iridescent wings of 14 different species of Morphidae: spectroscopic measurements under various incidences and gonioscopic measurements for a given incidence angle and wavelength. The first allows a determination of the index of refraction of the cuticular material. The second leads to the drawing of spatial diffraction maps. It shows that most of the reflected light is diffracted laterally over a very large angle (90° < θ < 120°, according to the different species) and that this repartition depends of the polarization of incident light. As predicted by previous calculations, the dissymmetric structure of the ridge is responsible for the separation of the polarization modes in the various diffraction orders.

Coloration mechanisms and phylogeny of Morpho butterflies

“…In Morpho, with their thickness and spacing being in the ∼100 nm range, the lamellae create a multilayer that strongly reflects blue light. The number of layers, which determines the reflection intensity, varies with the species and type of scale (Gralak et al, 2001;Kinoshita et al, 2002;Plattner, 2004;Berthier et al, 2006). The multilayered scales are classified as iridescent because the reflectance spectrum depends on the angle of illumination.…”

Actions pédagogiques en nanosciences

“…On constate un phénomène de changement de couleurs suivant la manière dont on regarde l'objet, que l'on appelle : l'iridescence (6). Ce sujet fait appel à des notions abordées en première scientifique telles que le spectre électromagnétique, l'optique, la dispersion et des notions de terminale telles que les propriétés des ondes, les phénomènes de diffraction et d'interférences.…”

Actions de sensibilisation aux nanotechnologies Nano-Ecole IdF

“…Mais, dans le cas des plumes de certains oiseaux, des ailes de papillon et des opales, les couleurs sont structurelles, dites physiques, et donc liées à la structure nano/microscopique de l'objet. Ce module s'intéresse particulièrement au phénomène de changement de couleurs qui les caractérisent suivant la manière dont on regarde l'objet, que l'on appelle : l'iridescence [6]. Ces couleurs, largement présentes dans la nature avec pour exemples la plume de paon, l'opale, les papillons morpho bleus ou un objet artificiel tel que le cd, sont directement liées à l'organisation de la matière.…”