A biological sub-micron thickness optical broadband reflector characterized using both light and microwaves

Vukusic, Peter; Kelly, Richard S.; Hooper, Ian R.

doi:10.1098/rsif.2008.0345.focus

Cited by 54 publications

(74 citation statements)

References 32 publications

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“…The same thickness value was concluded for the lower lamina of the green scales of P. nireus butterflies (Trzeciak et al, 2012;Wilts et al, 2012b). However, rather different values exist in other cases; for instance, the thickness of the lower lamina of Argyrophorus argenteus scales is 120 nm (Vukusic et al, 2009), and the small white [Pieris rapae; see fig. 4a of Stavenga et al (Stavenga et al, 2004)] and the angled sunbeam butterfly [Curetis acuta; see fig.…”

Section: Thin Filmsmentioning

confidence: 58%

Colouration principles of nymphaline butterflies - thin films, melanin, ommochromes and wing scale stacking

Stavenga

Leertouwer

Wilts

2014

Journal of Experimental Biology

141

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The coloration of the common butterflies Aglais urticae (small tortoiseshell), Aglais io (peacock) and Vanessa atalanta (red admiral), belonging to the butterfly subfamily Nymphalinae, is due to the species-specific patterning of differently coloured scales on their wings. We investigated the scales' structural and pigmentary properties by applying scanning electron microscopy, (micro)spectrophotometry and imaging scatterometry. The anatomy of the wing scales appears to be basically identical, with an approximately flat lower lamina connected by trabeculae to a highly structured upper lamina, which consists of an array of longitudinal, parallel ridges and transversal crossribs. Isolated scales observed at the abwing (upper) side are blue, yellow, orange, red, brown or black, depending on their pigmentation. The yellow, orange and red scales contain various amounts of 3-OH-kynurenine and ommochrome pigment, black scales contain a high density of melanin, and blue scales have a minor amount of melanin pigment. Observing the scales from their adwing (lower) side always revealed a structural colour, which is blue in the case of blue, red and black scales, but orange for orange scales. The structural colours are created by the lower lamina, which acts as an optical thin film. Its reflectance spectrum, crucially determined by the lamina thickness, appears to be well tuned to the scales' pigmentary spectrum. The colours observed locally on the wing are also due to the degree of scale stacking. Thin films, tuned pigments and combinations of stacked scales together determine the wing coloration of nymphaline butterflies.

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Section: Thin Filmsmentioning

confidence: 58%

Colouration principles of nymphaline butterflies - thin films, melanin, ommochromes and wing scale stacking

Stavenga

Leertouwer

Wilts

2014

Journal of Experimental Biology

141

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“…Metallic to silvery whiteness occurs on some butterfly wings as the result of mixing structure colors reflected from the membrane scale. For example, the thickness between ribs and scale membrane on Argyrophorus argenteus (Nymphalidae) wings changes across the wing; although multiple reflective colors can be seen at the microscopic scale, bright metallic white appears at the macroscopic scale (28). The ease with which shining metallic whiteness could be distinguished from dull whiteness and other colors could be important for communication between butterflies and for the butterfly's evolution-devolution.…”

mentioning

confidence: 99%

Varying and unchanging whiteness on the wings of dusk-active and shade-inhabiting Carystoides escalantei butterflies

Yang

et al. 2017

Proc. Natl. Acad. Sci. U.S.A.

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Whiteness, although frequently apparent on the wings, legs, antennae, or bodies of many species of moths and butterflies, along with other colors and shades, has often escaped our attention. Here, we investigate the nanostructure and microstructure of white spots on the wings of Carystoides escalantei, a dusk-active and shadeinhabiting Costa Rican rain forest butterfly (Hesperiidae). On both males and females, two types of whiteness occur: angle dependent (dull or bright) and angle independent, which differ in the microstructure, orientation, and associated properties of their scales. Some spots on the male wings are absent from the female wings. Whether the angle-dependent whiteness is bright or dull depends on the observation directions. The angle-dependent scales also show enhanced retro-reflection. We speculate that the biological functions and evolution of Carystoides spot patterns, scale structures, and their varying whiteness are adaptations to butterfly's low light habitat and to airflow experienced on the wing base vs. wing tip.butterfly wings | whiteness | angle dependent | retro-reflection |

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“…'chirped'); and (iii) a stack of several single spatial frequency DBRs with narrow bandgaps on top of each other resulting in broadband reflection. Nature has mastered several of these optical structures, for example, chaotically spaced silver reflectors in fish [2], chirped bronze-coloured beetle reflectors [3] and silver butterfly wings that use a colour-additive technique [4]. Here, we describe for a novel optical and structural design for a broadband DBR, found in the silvery covering of squid eyes from the family Loliginidae.…”

Section: Introductionmentioning

confidence: 99%

A highly distributed Bragg stack with unique geometry provides effective camouflage for Loliginid squid eyes

Holt

Sweeney

Johnsen

et al. 2011

J. R. Soc. Interface.

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Cephalopods possess a sophisticated array of mechanisms to achieve camouflage in dynamic underwater environments. While active mechanisms such as chromatophore patterning and body posturing are well known, passive mechanisms such as manipulating light with highly evolved reflectors may also play an important role. To explore the contribution of passive mechanisms to cephalopod camouflage, we investigated the optical and biochemical properties of the silver layer covering the eye of the California fishery squid, Loligo opalescens. We discovered a novel nested-spindle geometry whose correlated structure effectively emulates a randomly distributed Bragg reflector (DBR), with a range of spatial frequencies resulting in broadband visible reflectance, making it a nearly ideal passive camouflage material for the depth at which these animals live. We used the transfer-matrix method of optical modelling to investigate specular reflection from the spindle structures, demonstrating that a DBR with widely distributed thickness variations of high refractive index elements is sufficient to yield broadband reflectance over visible wavelengths, and that unlike DBRs with one or a few spatial frequencies, this broadband reflectance occurs from a wide range of viewing angles. The spindle shape of the cells may facilitate self-assembly of a random DBR to achieve smooth spatial distributions in refractive indices. This design lends itself to technological imitation to achieve a DBR with wide range of smoothly varying layer thicknesses in a facile, inexpensive manner.

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A biological sub-micron thickness optical broadband reflector characterized using both light and microwaves

Cited by 54 publications

References 32 publications

Colouration principles of nymphaline butterflies - thin films, melanin, ommochromes and wing scale stacking

Colouration principles of nymphaline butterflies - thin films, melanin, ommochromes and wing scale stacking

Varying and unchanging whiteness on the wings of dusk-active and shade-inhabiting Carystoides escalantei butterflies

A highly distributed Bragg stack with unique geometry provides effective camouflage for Loliginid squid eyes

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