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- Front Matter: Volume 7782
- Learning from Nature
- Light in Art
- Light in Physical Systems
Front Matter: Volume 7782
Front Matter: Volume 7782
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This PDF file contains the front matter associated with SPIE Proceedings Volume 7782, including the Title Page, Copyright information, Table of Contents, Introduction, and the Conference Committee listing.
Learning from Nature
Huygens, Mackintosh, Dalí, and Medusa: Polarization engineering (and more?)
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As Christiaan Huygens must have felt in his bones but could not have articulated with a mathematical theory,
engineering of the polarization state of light is easily accomplished with anisotropic materials. Examine a crystal
to see that its capabilities are quite restricted by its rigid Cartesian morphology reminiscent of the straitened
designs of Charles Rennie Mackintosh. But let loose the genius of Salvador Dalí to transform straight rods into
the flowing tresses of Medusa, and you begin to appreciate what all can be done to the polarization state by
nanoengineering morphology such that it is locally cartesian but globally curvilinear. If you exclaim "What
rot!," a few simple examples may suffice to convince you that engineering of both the polarization state and
the operating frequency band can be accomplished by nanoengineering the morphology of complex substances
called sculptured thin films (STFs). These nanoengineered metamaterials offer other promises too.
Light confinement in marine centric diatoms: main characteristics and wavelength dependence
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Valves of Coscinodiscus wailesii diatoms, monocellular micro-algae characterized by a diameter between 100 and 200
μm, show regular pores patterns which confine light in a spot of few μm2. This effect can be ascribed to the
superposition of diffracted wave fronts coming from the pores on the valve surface. We studied the transmission of
partially coherent light, at different wavelengths, through single valves of Coscinodiscus wailesii diatoms. The spatial
distribution of transmitted light strongly depends on the wavelength of the incident radiation. Numerical simulations
help to demonstrate how this effect is not present in the ultraviolet region of the light spectrum, showing one of the
possible evolutionary advantages represented by the regular pores patterns of the valves.
Structural color in beetles of South America
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Photonic microstructures in nature, specifically in endemic species of Coleoptera from Argentina and the south
of Chile have been identified, analyzed and modeled. These natural systems produce partial photonic bandgaps
(PBGs) as a result of the high periodicity of the microstructures found in some parts of their bodies. With
the aid of scanning (SEM) and transmission (TEM) electron microscopy we have identified that the elytron
(modified forewing of a beetle that encases the thin hind wings used in flight) of these insects shows a periodic
structure which originates diffractive phenomena resulting in extraordinary physical effects such as iridescent or
metallic colors. We measured the reflectance spectrum and obtained the chromaticity diagrams of the samples
with an Ocean Optics 4000 spectrophotometer. The geometrical parameters of the structure were obtained by
processing the SEM images with the ImageJ software, to introduce them in our electromagnetic model. In all
cases, a satisfactory agreement between the measurements and the numerical results was obtained. This permits
us to explain the mechanism of color production in those specimens. The study of structural colors in the
natural world can inspire the development of artificial devices with particular applications in technology, such
as intelligent sensors and new kinds of filters.
Light in Art
High-resolution infrared imaging
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The hands and mind of an artist are intimately involved in the creative process of image formation, intrinsically making
paintings significantly more complex than photographs to analyze. In spite of this difficulty, several years ago the artist
David Hockney and I identified optical evidence within a number of paintings that demonstrated artists began using
optical projections as early as c1425 - nearly 175 years before Galileo - as aids for producing portions of their images.
In the course of our work, Hockney and I developed insights that I have been applying to a new approach to
computerized image analysis. Recently I developed and characterized a portable high resolution infrared for capturing
additional information from paintings. Because many pigments are semi-transparent in the IR, in a number of cases IR
photographs ("reflectograms") have revealed marks made by the artists that had been hidden under paint ever since they
were made. I have used this IR camera to capture photographs ("reflectograms") of hundreds of paintings in over a
dozen museums on three continents and, in some cases, these reflectograms have provided new insights into decisions
the artists made in creating the final images that we see in the visible.
Light in Physical Systems
Linear and nonlinear control of ballistic trajectory of airy beams
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We demonstrate linear and nonlinear control of the ballistic trajectory of an optical beam. Such control is realized by
sending a Gaussian beam into a phase mask and then turn it into an accelerating Airy beam. We show how an optical
beam can be set into motion in a general ballistic trajectory, while the range and height of the trajectory can be
controlled at ease. In addition, we study linear propagation of deformed Airy beams in free space by varying the angle
between two "wings", which leads to wing flipping and change in acceleration. Finally, we demonstrate nonlinear
control of two-dimensional Airy beams with self-focusing and self-defocusing nonlinearities, and found that the Airy
beams initially driven by a self-defocusing nonlinearity exhibit anomalous diffraction and can be more robust as
compared to those driven by a self-focusing nonlinearity. Our results bring about a possibility to send an intense laser
beam into any desired location, passing through disordered media and getting over obstacles.
Observing light in nature from an airplane window
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Photographs taken from commercial airplanes of optical phenomena in nature, such as rainbows, halos, glories, and sky
colors, are shown to illustrate the variety of optical displays that can be observed by an informed and alert observer from
an airplane window. Observing tips are provided to enhance the probability of seeing certain phenomenon, based on the
time of day, location, and direction of travel of the airplane. Generally, a seat on the sun-ward side of the plane provides
opportunities to observe halos, coronas, iridescence, glitter patterns, crepuscular rays, sunsets and twilight colors, while a
seat opposite the sun provides opportunities to observe glories, rainbows, cloud bows, Earth's shadow, cloud shadows,
contrail shadows, and other shadow phenomena. On flights at high latitudes, (north- or south-) pole-facing seats can
sometimes provide opportunities for viewing somewhat more exotic phenomena, such as noctilucent clouds and auroras.
Vortices in generalized Stokes parameters
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Presence of vortices/phase singularities has been demonstrated in instantaneous generalized Stokes parameters (IGSP) of
the field generated by illuminating a random phase screen with a polarization structured beam. Polarization structuring is
achieved by focusing the vector beam with tilt in one of the orthogonal polarization components with respect to other.
Spatially structured polarized beam is scattered by non-birefringent random phase screen placed at the focal plane of
focusing lens. Field distribution of orthogonal polarization components are evaluated at the focal plane of second lens,
and subsequently IGSPs are evaluated. Evaluations of the IGSPs are performed by varying one observation point r2 with
respect to a fixed reference point r1. Distribution of phase singularities is displayed in the phase map of IGSP. These
singularities disappear in the spatially averaged generalized stokes parameters.
Experimental investigation of critical points in optical coherence function
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By using an unconventional holography, referred to as coherence holography, developed recently, we will explore the
whole phase field in an optical coherence function and present the direct experimental investigation to the coherence
critical points, including coherence phase saddles, coherence phase extrema and coherence phase singularities. We have
observed the local phase structures around the coherence critical points, and studied the relationship between the saddles
and the extrema in the optical coherence function. Some topological rules associated with the coherence critical points,
such as topological sign rule governing the coherence vortices and topological index conservation during the reaction of
the coherence vortices, are also investigated by experiments.
Dynamic quantitative phase images of pond life, insect wings, and in vitro cell cultures
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This paper presents images and data of live biological samples taken with a novel Linnik interference
microscope. The specially designed optical system enables instantaneous and 3D video measurements of
dynamic motions within and among live cells without the need for contrast agents. This "label-free", vibration
insensitive imaging system enables measurement of biological objects in reflection using harmless light levels
with current magnifications of 10X (NA 0.3) and 20X (NA 0.5) and wavelengths of 660 nm and 785 nm over
fields of view from several hundred microns up to a millimeter. At the core of the instrument is a phasemeasurement
camera (PMC) enabling simultaneous measurement of multiple interference patterns utilizing a
pixelated phase mask taking advantage of the polarization properties of light. Utilizing this technology enables
the creation of phase image movies in real time at video rates so that dynamic motions and volumetric changes
can be tracked. Objects are placed on a reflective surface in liquid under a coverslip. Phase values are
converted to optical thickness data enabling volumetric, motion and morphological studies. Data from a
number of different mud puddle organisms such as paramecium, flagellates and rotifers will be presented, as
will measurements of flying ant wings and cultures of human breast cancer cells. These data highlight
examples of monitoring different biological processes and motions. The live presentation features 4D phase
movies of these examples.