Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

From unconventional laser beams to a more robust imaging wave

08.08.2016

Here's the scene: a suspicious package is found in a public place. The police are called in and clear the area. Forced to work from a distance and unable to peer inside, they fear the worst and decide to detonate the package.

New research at the University of Rochester might help authorities in the not-too-distant future be better informed in tackling such situations and do so more safely. Working with a special type of electromagnetic wave--called terahertz (THz)--that's capable of sensing and/or imaging objects behind barriers, the team demonstrated that they can detect a THz wave at a distance of up to 100 feet.


Creating a more robust terahertz wave from an Airy beam.

(Graphic by Michael Osadciw/University of Rochester)

The THz wave created by the researchers is more than five times stronger than what is generated by more conventional means, leading them to believe that a THz wave--and the image of a hidden object--can be detected at much greater distances in the future.

The research project was led by Kang Liu, a PhD student in optics, and Xi-Cheng Zhang, the M. Parker Givens Professor of Optics and the director of the Institute of Optics, in collaboration with a group from Greece led by Tzortzakis Stelios. The results have been published in the journal Optica.

"The use of an unconventional laser beam in our project goes beyond a scientific curiosity," said Zhang. "It makes possible the remote sensing of chemical, biological, and explosive materials from a standoff distance."

THz waves, which fall between microwave and the infrared band on the electromagnetic spectrum, can penetrate certain solid objects that are opaque to visible light to create images of what is hidden from view. Unlike traditional x-rays, the waves do so without damaging human tissue.

All that makes THz waves a promising tool for Homeland Security and other law enforcement agencies. But before THz waves can be widely used, a number of obstacles need to be overcome, including how to make them more effective over greater distances.

One of the drawbacks is that the waves are absorbed by water molecules in the air and weaken significantly over longer distances, making them generally ineffective. One solution is to generate the THz waves near the target, so that they have only a short distance to travel. It's also important that the waves are intensive, because, as Liu points out, "The stronger the terahertz wave, the more work it can do."

The key to their results was the use of a specific exotic laser beam--called a ring-Airy beam--to generate a THz wave that has 5.3 times the pulse energy of THz waves created with standard Gaussian beams.

Ordinary beams of light spread out as they travel, but that's not the case with ring-Airy beams, which curve toward the center from all points.

To begin the process, Liu directed a laser beam onto a spatial light modulator (SLM), which formed the ring-Airy beam. As the name indicates, the beam is circular with a hollow center. Instead of spreading out as it travels, the beam collapsed inward, creating an intensely excited region of free electrons--called a plasma. Those electrons, in turn, generated the THz wave, which would be capable of penetrating a nearby target and reflecting images or providing vital chemical information about what is hidden.

"When the target is a suspected explosive device, it's important to get the work done at a safe distance," said Liu. "We believe our method could help THz remote sensing from more than 100 feet away by providing a more robust and flexible way to generate THz remotely."

The modulator allowed the researchers to change the size of the ring-Airy beam and fine-tune the dimensions of the plasma that is created. The next step, as Liu sees it, is to manipulate ring-Airy beams to create stronger THz waves over greater distances.

Funding for the research project was provided by the US Army Research Office, "Laserlab-Europe", and the General Secretariat for Research and Technology Aristeia project "FTERA."

Media Contact

Peter Iglinski
peter.iglinski@rochester.edu
585-273-4726

 @UofR

http://www.rochester.edu 

Peter Iglinski | EurekAlert!

More articles from Physics and Astronomy:

nachricht UNH scientists help provide first-ever views of elusive energy explosion
16.11.2018 | University of New Hampshire

nachricht NASA keeps watch over space explosions
16.11.2018 | NASA/Goddard Space Flight Center

All articles from Physics and Astronomy >>>

The most recent press releases about innovation >>>

Die letzten 5 Focus-News des innovations-reports im Überblick:

Im Focus: UNH scientists help provide first-ever views of elusive energy explosion

Researchers at the University of New Hampshire have captured a difficult-to-view singular event involving "magnetic reconnection"--the process by which sparse particles and energy around Earth collide producing a quick but mighty explosion--in the Earth's magnetotail, the magnetic environment that trails behind the planet.

Magnetic reconnection has remained a bit of a mystery to scientists. They know it exists and have documented the effects that the energy explosions can...

Im Focus: A Chip with Blood Vessels

Biochips have been developed at TU Wien (Vienna), on which tissue can be produced and examined. This allows supplying the tissue with different substances in a very controlled way.

Cultivating human cells in the Petri dish is not a big challenge today. Producing artificial tissue, however, permeated by fine blood vessels, is a much more...

Im Focus: A Leap Into Quantum Technology

Faster and secure data communication: This is the goal of a new joint project involving physicists from the University of Würzburg. The German Federal Ministry of Education and Research funds the project with 14.8 million euro.

In our digital world data security and secure communication are becoming more and more important. Quantum communication is a promising approach to achieve...

Im Focus: Research icebreaker Polarstern begins the Antarctic season

What does it look like below the ice shelf of the calved massive iceberg A68?

On Saturday, 10 November 2018, the research icebreaker Polarstern will leave its homeport of Bremerhaven, bound for Cape Town, South Africa.

Im Focus: Penn engineers develop ultrathin, ultralight 'nanocardboard'

When choosing materials to make something, trade-offs need to be made between a host of properties, such as thickness, stiffness and weight. Depending on the application in question, finding just the right balance is the difference between success and failure

Now, a team of Penn Engineers has demonstrated a new material they call "nanocardboard," an ultrathin equivalent of corrugated paper cardboard. A square...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

VideoLinks
Industry & Economy
Event News

“3rd Conference on Laser Polishing – LaP 2018” Attracts International Experts and Users

09.11.2018 | Event News

On the brain’s ability to find the right direction

06.11.2018 | Event News

European Space Talks: Weltraumschrott – eine Gefahr für die Gesellschaft?

23.10.2018 | Event News

 
Latest News

Purdue cancer identity technology makes it easier to find a tumor's 'address'

16.11.2018 | Health and Medicine

Good preparation is half the digestion

16.11.2018 | Life Sciences

Microscope measures muscle weakness

16.11.2018 | Life Sciences

VideoLinks
Science & Research
Overview of more VideoLinks >>>