Silvery fish skin as an example of a chaotic reflector

McKenzie, David R.; Yin, Y.; McFall, W. D.

doi:10.1098/rspa.1995.0144

Cited by 52 publications

(63 citation statements)

References 7 publications

(2 reference statements)

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“…We also ran the model for isotropic high index layers with n x = n y = n z = 1.83 (Fig. 6a, left sketch), a model previously chosen by several authors (e.g., Denton and Land, 1971;Land, 1972;McKenzie et al, 1995). The model simulated reflection and polarization data under the same conditions as measured optically: (1) with angles of illumination α varying between -45 • and +45 • and a constant wavelength λ (averaged between 525 and 575 nm).…”

Section: Mathematical Modelingmentioning

confidence: 99%

Polarizing optics in a spider eye

Mueller

Labhart

2010

J Comp Physiol A

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Many arthropods including insects and spiders exploit skylight polarization for navigation. One of the four eye pairs of the spider Drassodes cupreus is dedicated to detect skylight polarization. These eyes are equipped with a tapetum that strongly plane-polarizes reflected light. This effectively enhances the polarization-sensitivity of the photoreceptors, improving orientation performance. With a multidisciplinary approach, we demonstrate that D. cupreus exploits reflective elements also present in non-polarizing tapetal eyes of other species such as Agelena labyrinthica. By approximately orthogonal arrangement of two multilayer reflectors consisting of reflecting guanine platelets, the tapetum uses the mechanism of polarization by reflection for polarizing reflected light.Polarizing optics in a spider eye AbstractMany arthropods including insects and spiders exploit skylight polarization for navigation. One of the four eye pairs of the spider Drassodes cupreus is dedicated to detect skylight polarization. These eyes are equipped with a tapetum that strongly plane-polarizes reflected light. This effectively enhances the polarization-sensitivity of the photoreceptors, improving orientation performance. With a multidisciplinary approach, we demonstrate that D. cupreus exploits reflective elements also present in nonpolarizing tapetal eyes of other species such as Agelena labyrinthica. By approximately orthogonal arrangement of two multilayer reflectors consisting of reflecting guanine platelets, the tapetum uses the mechanism of polarization by reflection for polarizing reflected light.

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Section: Mathematical Modelingmentioning

confidence: 99%

Polarizing optics in a spider eye

Mueller

Labhart

2010

J Comp Physiol A

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“…The optical structure of this eye covering is intriguingly different from the reported broadband reflecting structures in fish scales, because the average size and variation of both the high-and low-refractive index regions is up to ten times that described in fish scales, while the difference between high-and lowrefractive index is 0.23 rather than 0.5 (guanine, found in fish scales, has a refractive index of 1.83) [2]. Therefore, in addition to guanine-based reflectors, evolution has also fostered the formation of proteinaceous (therefore polymer-based) broadband dielectric reflectors with layers made from entire cells as a form of midwater camouflage.…”

Section: Introductionmentioning

confidence: 68%

“…These adjustments are typically used to reduce either undetectable or suppressed FabryPerot oscillations caused by multiple coherent reflections within layers with thicknesses greater than the incident wavelength. Models similar to this have been used in other work such as those studying chaotic fish scale reflectors and ordered Bragg reflections in cephalopod skin [2,15]. Using the transfer-matrix model, we can gain insights into how the distribution of layer thicknesses in the silver reflector stack affects the specular reflectance at any incident angle.…”

Section: Optical Modellingmentioning

confidence: 99%

“…'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%

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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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“…In a chaotic configuration, the thickness of reflecting elements and the spacing between them are random [15]. The chirped stack model has been found in beetles [13,16], and the other two models have been found in various fish species [15,17].…”

Section: Introductionmentioning

confidence: 99%

Broadband and polarization reflectors in the lookdown,Selene vomer

Zhao

Brady

Gao

et al. 2015

J. R. Soc. Interface.

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Predator evasion in the open ocean is difficult because there are no objects to hide behind. The silvery surface of fish plays an important role in open water camouflage. Various models have been proposed to account for the broadband reflectance by the fish skin that involve one-dimensional variations in the arrangement of guanine crystal reflectors, yet the three-dimensional organization of these guanine platelets have not been well characterized. Here, we report the three-dimensional organization and the optical properties of integumentary guanine platelets in a silvery marine fish, the lookdown (Selene vomer). Our structural analysis and computational modelling show that stacks of guanine platelets with random yaw angles in the fish skin produce broadband reflectance via colour mixing. Optical axes of the guanine platelets and the collagen layer are aligned closely and provide bulk birefringence properties that influence the polarization reflectance by the skin. These data demonstrate how the lookdown preserves or alters polarization states at different incident polarization angles. These optical properties resulted from the organization of these guanine platelets and the collagen layer may have implications for open ocean camouflage in varying light fields.

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Silvery fish skin as an example of a chaotic reflector

Cited by 52 publications

References 7 publications

Polarizing optics in a spider eye

Polarizing optics in a spider eye

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

Broadband and polarization reflectors in the lookdown,Selene vomer

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