background image
grams that are smoothly varying and create com-
plex patterns seamlessly, there are no dividing
lines or pixels, unless they are actually desired.
This prevents light from ¡°leaking¡± out of the pat-
tern and corrupting the signal coming out of the
hologram.
From the lab to the stars
After creating the DWLS, Escuti looked for po-
tential applications. And that search brought him
to a team of astronomers at Leiden University,
including Frans Snik, Matthew Kenworthy, and
Christoph Keller.
For years, astronomers have devised telescopes
that, in theory, can use light to help them unravel
the mysteries of the universe. But these theoreti-
cal designs were often hampered by the limits of
technology.
¡°Light is everything in astronomy, it¡¯s the carrier
of almost all information and knowledge we have
of the universe,¡± says Snik.
Now Escuti was being asked to help turn theory
into reality.
¡°The astronomers I am working with at Leiden
had ideas for novel components and instrument designs that could make
better use of the light collected by telescopes,¡± Escuti says. ¡°They wanted
to know if we could make holograms with specific characteristics that had
previously been technologically impossible. And we could.¡±
For example, he said, his team has provided the astronomers with geomet-
ric phase holograms that they have used to build advanced coronagraphs,
telescopes that can see things close to stars, to study exoplanets beyond our
solar system.
¡°They wanted to redistribute the blazing light of the halo around a star, so
that the faint light coming from a planet orbiting that star can be observed
with better contrast and then analyze the planet¡¯s light to learn about its
composition and other characteristics,¡± Escuti says. ¡°They¡¯re now able to do
that with better performance than ever before. We¡¯ve been working with
them for a few years now, and have created several new astronomical tools.¡±
Snik added the new options offered by their technology provides significant
new potential for astronomical research.
¡°With these components and techniques, we have for the first time in per-
haps many decades fundamentally expanded the astronomer¡¯s toolkit for
manipulating light from astronomical sources,¡± he said.
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Unprecedented Control Over Behavior Of Light Achieved
Direct-write laser scanner allows creation of nearly perfect geometric phase holograms
Kokanee Salmon
give-away... Pg 10
Operation Christmas
Child begins... Pg 4
A room full of
treasure!... Pg 5
Michael Martin
Murphey in GJ...Pg 12
October 21, 2015: In 2010, Michael Escuti re-
ceived funding from the National Science Foun-
dation (NSF) to study and make novel hologram
technologies and he created a tool that did much
more.
The technology created is a new way to ma-
nipulate light, with applications from studying
alien worlds to making cellphones more energy
efficient.
¡°Not long after we received the NSF funding, we
were able to create something called the direct-
write laser scanner (DWLS), which allows us
to create nearly perfect geometric phase holo-
grams,¡± says Escuti, an engineer at North Caro-
lina State University.
¡°They look like flat, semi-translucent plates, but
they give us unprecedented control over the
behavior of light. We can use them to make more
efficient displays for mobile devices, sensors with
greater resolution, and, frankly, we¡¯re still dis-
covering all of the potential applications for this
technology.¡±
To make geometric phase holograms, the DWLS
2015 NOVEMBER #6-10
¡®prints¡¯ using an ultraviolet laser on a super-thin film, only about 50 nano-
meters thick. The film is made of a photoreactive polymer that responds to
both the intensity and the polarization of the light. When the DWLS is done
printing, a much thicker layer of liquid crystal is applied, amplifying the
pattern on the underlying thin film.
To understand how the DWLS works, you have to understand that it
doesn¡¯t have an inkjet, it prints light, and it prints in four dimensions.
The DWLS prints in horizontal and vertical dimensions, just like a regular
printer. And it can also vary the intensity of the light. But, crucially, it is
also capable of controlling the orientation angle of the linear polarization of
the light.
Think of a beam of light as a wiggling wave, which vibrates in a perpendic-
ular direction relative to the direction it is traveling. Control of the orienta-
tion angle of the linear polarization of light means control of the direction
that the wave is wiggling. And this polarization angle can be manipulated
without changing the angle the light is traveling.
In other words, a laser can be pointed directly at an object and, while the
polarization angle may change, the direction of the laser beam relative to
the object stays the same.
One reason the DWLS is unique is that it produces geometric phase holo-
The Amsterdam Central ¡®Rainbow Station¡¯ project
by artist Daan Roosegaarde was made possible by
geometric phase hologram technology. In layman¡¯s
terms, it¡¯s a filter that takes in bright white light
and turns it into a rainbow, ¡®dispersing¡¯ the colors
in a precise, controlled way.
Photo credit: Studio Roosegaarde