Researchers find way to create wide variety of new holograms

November 10, 2015 by Matt Shipman
Researchers find way to create wide variety of new holograms
Top Row: Three images of the NC State logo as viewed through a geometric phase hologram, in this case a lens, where each corresponds to one of the three possible wavefronts. Bottom Row: Illustrations, simulation, and microscope picture showing the liquid crystal orientation created by the light patterning techniques reported in the paper, showing a lens profile (left image) and a far-field hologram profile (right three images).

Researchers at North Carolina State University have developed techniques that can be used to create ideal geometric phase holograms for any kind of optical pattern – a significant advance over the limitations of previous techniques. The holograms can be used to create new types of displays, imaging systems, telecommunications technology and astronomical instruments.

A geometric phase hologram is a thin film that manipulates . Light moves as a wave, with peaks and troughs. When the light passes through a geometric phase hologram, the relationship between those peaks and troughs is changed. By controlling those changes, the hologram can focus, disperse, reorient or otherwise modify the light.

An ideal geometric phase hologram modifies the light very efficiently, meaning that little of the light is wasted. But ideal geometric phase holograms can also produce three different, well-defined "wavefronts" – or transformed versions of the light that passes through the thin film.

"We can direct light into any one or more of those three wavefronts, which allows us to use a single ideal geometric phase hologram in many different ways," says Michael Escuti, a professor of electrical and computer engineering at NC State and corresponding author of a paper on the work.

Previously, researchers were only able to make ideal geometric phase holograms in a limited set of simple patterns, curtailing their usefulness for new applications. This is because making these holograms involves orienting molecules or structures at a scale smaller than the wavelength of light.

"We've come up with two ways of making ideal geometric phase holograms that are relatively simple but allow us to control the orientation of the molecules that ultimately manipulate the light," Escuti says.

First, the researchers use lasers to create a high-fidelity light pattern, either by taking advantage of how waves of light interfere with each other, or by using a tightly focused laser to scan through a pattern – much like a laser printer.

A photoreactive substrate records the light pattern, with each molecule in the substrate orienting itself depending on the polarization of the light it was exposed to. To understand this, think of a beam of light as a wavy string, traveling from left to right. That string is also vibrating up and down – creating wiggles are that are perpendicular to the direction the string is traveling. Controlling the orientation angle of the light's linear polarization just means controlling the direction that the wave is wiggling.

The pattern that is recorded on the substrate then serves as a template for a liquid crystal layer that forms the finished hologram.

"Using these techniques, we're able to create ideal geometric phase holograms in nearly any pattern," Escuti says. "Theoretically, there are patterns that are too small for us to make, but we've been able to make patterns for every practical application we've addressed so far – from astronomical instruments to art installations.

"This work gave us a great deal of insight into controlling the spatial properties of light waves," Escuti says. "We're now exploring how we can better manipulate the spectrum of . For example, we're determining how we can handle visible light and infrared light differently within a single hologram."

Escuti is also working with his company, ImagineOptix Corporation, to develop new applications and improve existing technologies that may benefit from higher efficiency thin-films.

Explore further: Novel tech that manipulates light has applications beyond holograms

More information: Jihwan Kim et al. Fabrication of ideal geometric-phase holograms with arbitrary wavefronts, Optica (2015). DOI: 10.1364/OPTICA.2.000958

Related Stories

Quantum holograms as atomic scale memory keepsake

October 21, 2014

Russian scientists have developed a theoretical model of quantum memory for light, adapting the concept of a hologram to a quantum system. These findings from Anton Vetlugin and Ivan Sokolov from St. Petersburg State University ...

Printable holograms could make holograms more widespread

August 6, 2015

(Phys.org)—Holograms have a wide variety of applications, from 3D displays to data storage, but the potential applications are currently limited by the complexity and cost of hologram fabrication. In an attempt to simplify ...

Recommended for you

Scientists discover superconductor with bounce

October 23, 2017

The U.S. Department of Energy's Ames Laboratory has discovered extreme "bounce," or super-elastic shape-memory properties in a material that could be applied for use as an actuator in the harshest of conditions, such as outer ...

Scientists update four key fundamental constants

October 23, 2017

Paving the way for transforming the world's measurement system, an international task force has determined updated values for four fundamental constants of nature. The updated values comprise the last scientific piece of ...

Experiment provides deeper look into the nature of neutrinos

October 23, 2017

The first glimpse of data from the full array of a deeply chilled particle detector operating beneath a mountain in Italy sets the most precise limits yet on where scientists might find a theorized process to help explain ...

2 comments

Adjust slider to filter visible comments by rank

Display comments: newest first

TiagoTiago
not rated yet Nov 10, 2015
Is this just analog, or can they have a computer generate the pattern and produce the pattern automatically?
Osiris1
not rated yet Nov 11, 2015
When do we get our holodeck like Star Trek. Complete with supermodels?

Please sign in to add a comment. Registration is free, and takes less than a minute. Read more

Click here to reset your password.
Sign in to get notified via email when new comments are made.