Nav: Home

Technique makes more efficient, independent holograms

April 04, 2017

Not far from where Edwin Land -- the inventor of the Polaroid camera -- made his pioneering discoveries about polarized light, researchers from the Harvard John A. Paulson School of Engineering and Applied Sciences (SEAS) are continuing to unlock the power of polarization.

Recently, a team of researchers led by Federico Capasso, the Robert L. Wallace Professor of Applied Physics and Vinton Hayes Senior Research Fellow in Electrical Engineering, encoded multiple holographic images in a metasurface that can be unlocked separately with differently polarized light.

This advancement could improve holograms for anti-fraud protection and entertainment, as well as offer more control over the manipulation and measurement of polarization. The research was published in Physical Review Letters.

"The novelty of this type of metasurface is that for the first time we have been able to embed vastly different images that don't look at all like each other -- like a cat and a dog -- and access and project them independently using arbitrary states of polarization," said Capasso, the senior author of the paper.

Polarization is the path along which light vibrates. Previous research from the Capasso lab used nanostructures sensitive to polarization to produce two different images encoded in the metasurface. However, those images were dependent on one another, meaning both were created but only one appeared in the field of vision.

The metasurface made of titanium dioxide, a widely available material, consists of an array of polarization-sensitive pillars -- also called nanofins -- that redirect the incident light. Unlike previous arrays, which were uniform in size, these nanofins vary in orientation, height and width, depending on the encoded images.

"Each nanofin has different, precisely controllable polarization properties," said Noah Rubin, co-first author of the paper and graduate student in the Capasso Lab. "You use this library of elements to design the encoded image."

Different polarizations read different elements.

"This metasurface can be encoded with any two images, and unlocked by any two polarizations, so long as they are perpendicular to each other," said Rubin. "You can also embed different functionalities. It can be a lens for one polarization and if you go to a different polarization, it can be a hologram. So, this work is general statement about what can be done with metasurfaces and enables new optics for polarization."

"This is another powerful example of metasurfaces," said Capasso. "It allows you to compress a number of functionalities, which would normally spread over several components, and put them all in a single optical element."
-end-
This research was coauthored by J. P. Balthasar Mueller, Robert Devlin and Benedikt Groever. It was supported in part by the Air Force Office of Scientific Research.

Harvard John A. Paulson School of Engineering and Applied Sciences

Related Engineering Articles:

Engineering a new cancer detection tool
E. coli may have potentially harmful effects but scientists in Australia have discovered this bacterium produces a toxin which binds to an unusual sugar that is part of carbohydrate structures present on cells not usually produced by healthy cells.
Engineering heart valves for the many
The Wyss Institute for Biologically Inspired Engineering and the University of Zurich announced today a cross-institutional team effort to generate a functional heart valve replacement with the capacity for repair, regeneration, and growth.
Geosciences-inspired engineering
The Mackenzie Dike Swarm and the roughly 120 other known giant dike swarms located across the planet may also provide useful information about efficient extraction of oil and natural gas in today's modern world.
Engineering success
Academically strong, low-income would-be engineers get the boost they need to complete their undergraduate degrees.
HKU Engineering Professor Ron Hui named a Fellow by the UK Royal Academy of Engineering
Professor Ron Hui, Chair Professor of Power Electronics and Philip Wong Wilson Wong Professor of Electrical Engineering at the University of Hong Kong, has been named a Fellow by the Royal Academy of Engineering, UK, one of the most prestigious national academies.
More Engineering News and Engineering Current Events

Best Science Podcasts 2019

We have hand picked the best science podcasts for 2019. Sit back and enjoy new science podcasts updated daily from your favorite science news services and scientists.
Now Playing: TED Radio Hour

Teaching For Better Humans
More than test scores or good grades — what do kids need to prepare them for the future? This hour, guest host Manoush Zomorodi and TED speakers explore how to help children grow into better humans, in and out of the classroom. Guests include educators Olympia Della Flora and Liz Kleinrock, psychologist Thomas Curran, and writer Jacqueline Woodson.
Now Playing: Science for the People

#535 Superior
Apologies for the delay getting this week's episode out! A technical glitch slowed us down, but all is once again well. This week, we look at the often troubling intertwining of science and race: its long history, its ability to persist even during periods of disrepute, and the current forms it takes as it resurfaces, leveraging the internet and nationalism to buoy itself. We speak with Angela Saini, independent journalist and author of the new book "Superior: The Return of Race Science", about where race science went and how it's coming back.