APS March Meeting 2010
Volume 55, Number 2
Monday–Friday, March 15–19, 2010;
Portland, Oregon
Session V4: Biological Nanostructures for Photonics and Adhesion
8:00 AM–11:00 AM,
Thursday, March 18, 2010
Room: Oregon Ballroom 204
Sponsoring
Unit:
DPOLY
Chair: Mohan Srinivasrao, Center for Advnaced Research on Optical Microscopy
Abstract ID: BAPS.2010.MAR.V4.4
Abstract: V4.00004 : Mechanism of the tunable structural color of neon tetra
9:48 AM–10:24 AM
Preview Abstract
Abstract
Author:
Shinya Yoshioka
(Osaka University)
Many examples of the structural color can be found in butterfly
wings,
beetle's elytra and bird feathers. Since the color-producing
microstructures
of these examples mainly consist of stable materials, for
example, dried
cuticles in insects and keratin and melanin granules in bird
feathers, it is
impossible to actively change the microstructure. On the other
hand, some
fish have the tunability in their structural colors. For example,
a small
tropical fish, neon tetra, has a longitudinal stripe that looks
blue-green
in the day time, while it changes into deep violet at night. This
fact
clearly indicates the variability in the microstructure. It is
known that
the iridophore of the stripe part of neon tetra contains two
stacks of thin
light-reflecting platelets that are made of guanine crystal.
Since the
arrangement of the platelets is observed periodic, the stack is
thought to
cause the structural color through the multilayer thin-film
interference.
Consequently, the variability in the color is thought to
originate from the
variation in the distance between the platelets. Two explanations
have been
proposed so far for the distance variation. Lythoge and Shand
considered
that the distance is controlled by osmotic pressure that induces
the inflow
of the water into the iridophore[1]. On the other hand, Nagaishi
et al.
proposed a different model, called Venetian blind model, in which
the
inclination angle of the platelets is varied, resulting in the
change in the
distance[2]. Recently, we have performed detailed optical
measurements on
the iridophore of neon tetra. We have paid particular attention
to the
direction of the reflected light, since the Venetian blind model
expects
that the direction varies with the color change owing to the tilt
of the
platelets. We present the experimental results and quantitatively
discuss
the validity of the Venetian blind model.
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[1] J. N. Lythgoe, and J. Shand, J Physiol. 325, 23-34 (1982).
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[2] H. Nagaishi, N. Oshima, and R. Fujii, Comp. Biochem. Physiol.
95A, 337-341 (1990).
To cite this abstract, use the following reference: http://meetings.aps.org/link/BAPS.2010.MAR.V4.4