Photonic Structures in Nature - Bionanotechnology: Global Prospects - page 508

800

700

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500

-20° 0° 30°

400

-40 -20 0 20 40

Angle
(a) (b)

FIGURE 25.10
(See.color.insert.).(a).Graph.showing.the.relection.measured.when.a.scale.from. E. schoenherri pettiti .is.rotated.
around.the.azimuthal.θ.axis,.with.the.relection.spectra.recorded.by.a.microspectrometer..(b).Image.of.the.scale.
examined.in.1.10.at.three.angles.of.incidence:.-20°,.0°,.and.30°..The.larger.black.circle.encompasses.the.region.
that.the.spectra.in.Figure.25.10a.was.measured.on..The.smaller.black.circle.shows.another.domain.that.displays.
a.similar.color.progression..Scale.bars:.(b).80.μm..(With.permission.)

25.2.2 Parides sesostris

The.butterly. P. sesostris .has.scales.of.type.IIIa.that.are.colored.by.an.inverse-opal.structure..
They.comprise.a.3D.lattice.of.cuticle.consisting.of.an.array.of.spherical.holes.in.a.matrix.of.
cuticle..The.order.of.this.system.leads.to.strong.scattering.of.favored.wavelengths..As.with.
most. structures. of. this. type,. the. lattices. are. arranged. into. small,. irregular,. but. distinct.
domains.that.neighbor.each.other.and.bear.slightly.different.characteristic.wavelengths,.
the.constant.color.effect.across.the.wing.being.the.result.of.spatial.averaging. 26
In. P. sesostris ,.the.scales.of.the.bright.green.patches.on.the.wings.of.the.butterly.display.
a.series.of.domains.when.examined.under.a.microscope..These.domains.display.a.series.
of.similar.colors,.which.creates.a.constant.color.effect..Examination.by.electron.microscope.
shows.a.highly.ordered.inverse-opal.structure.within.the.bulk.of.the.scale,.and.that.the.
domains.are.caused.by.their.being.ordered.into.different.orientations.(Figure 25.11.)
Illuminating. the. scales. with. polarized. light. and. observing. with. a. crossed. polarizer.
again. reveals. polarization. conversion. of. lower. wavelengths. from. different. domains.. As.
the.scale.is.rotated.while.observed.with.a.crossed.polarizer.setup,.the.intensity.of.relec-
tion.from.different.domains.changes..This.is.caused.by.a.system.similar.to.that.observed.

(a) (b)

FIGURE 25.11
(a).SEM.images.from.the.wing.of. P. sesostris ..(b).TEM.image.from. P. sesostris .showing.the.domain.within.the.scales..
Scale.bars:.1.2.μm.(a),.750.μm.(b)..(From.Vukusic,.P.,.and.Sambles,.J.R.,. Nature ,.424,.852-855,.2003.).(With.permission)