Biomedical Engineering Reference
In-Depth Information
(a)
(b)
(c)
(d)
FIGURE 25.4
(See.color.insert.).Optical.and.TEM.images.of.the.butterlies. Morpho rhetenor .(a,.b).and. Morpho didius .(c,.d)..Both.
optical. images. (a,. c). show. the. brilliant. blue. that. is. synonymous. with. this. family. of. butterlies.. The. two. TEM.
images.(b..and.d.).show.the.substructure.of.the.butterly.scales..TEM.image.of.a.section.from.a. M. rhetenor .scale.
(b.).shows.the.multilayer.within.the.ridges.responsible.for.the.brilliant.colour,.while.the.image.from.a.section.of.
M. didius .(d.).shows.the.two.discretely.condigured.multilayers..Scale.bars:.20 mm.(a),.1.8.μm.(b),.20.mm.(c),.1.3.μm.
(d)..(From.Vukusic,.P.,.and.Sambles,.J.R.,. Nature ,.424,.852-855,.2003..With.permission.)
ridges.is.in.the.region.of.950.nm,.allowing.room.for.only.six.or.seven.lamellae..The.upper.
layer.has.fewer.ridges.that.are.1,700.nm.apart.and.1,200.nm.high.with.four.or.ive.lamellae.
present.toward.the.top.of.the.ridge..Macroscopically.the.effect.is.very.similar.to.that.of. M.
rhetenor ..However,.the.semitransparent.upper.scale.strongly.diffracts.the.transmitted.light,.
and.this.enhances.the.observed.scattering..The.result.is.a.classically.high-relecting.scale.
that.is.viewable.over.a.wide.angle.
25.1.4 Ancyluris meliboeus and Hypolimnas bolina
In.the. Morpho .butterlies,.the.lamellae.run.virtually.parallel.to.the.surface.of.the.scale,.and.
therefore.the.wing..In.a.number.of.other.butterlies,.the.scales.contain.lamellae.that.are.ori-
ented.at.an.angle.that.is.between.perpendicular.and.parallel.to.the.base.of.the.ridges..This.
reduces.the.number.of.layers.that.act.in.the.multilayer.stack,.as.well.as.the.total.relectivity.
that.can.be.achieved.from.the.structure,.but.it.also.has.the.effect.of.creating.a.“dark.zone”.
within.the.observation.hemisphere,.in.which.there.is.an.angle.range.where.no.iridescence.
is.observed.
Both.the.butterlies. Ancyluris meliboeus .and. Hypolimnas bolina .have.scales.with.this.form.
of.structure.(Figure 25.5.).In.the.case.of. A. meliboeus ,.the.scales.have.what.can.be.loosely.
described.as.ridges.that.are.split.along.their.length.into.plates.that.are.inclined.to.around.
30°.from.parallel.to.their.base..These.lamellae.act.as.a.multilayer,.and.its.incline.results.in.
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