Featured Research

from universities, journals, and other organizations

Yankee Ingenuity: Dartmouth Physicists Convert A Microcope Into A Free-Electron Laser

Date:
November 12, 1998
Source:
Dartmouth College
Summary:
A team of researchers led by a Dartmouth physicist has built the first table-top free-electron laser capable of producing a bright, tunable beam of infrared light. The prototype device -- built around a souped-up scanning electron microscope scavenged from colleagues -- replaces the stadium-sized accelerators used in current generation free-electron lasers with an apparatus no bigger than two large suitcases.

A team of researchers led by a Dartmouth physicist has built the first table-top free-electron laser capable of producing a bright, tunable beam of infrared light. The prototype device -- built around a souped-up scanning electron microscope scavenged from colleagues -- replaces the stadium-sized accelerators used in current generation free-electron lasers with an apparatus no bigger than two large suitcases. The total power available from the much smaller device is low compared to that of the large machines, but well-matched to the needs of many important applications in such fields as atmospheric physics, chemistry, medicine and radio astronomy.

The work by Dartmouth physics professor John Walsh and colleagues provides a versatile new tool for probing the largely hidden far infrared spectrum, opening a window into such things as the dynamics in mesoscopic structures -- man-made molecular machines as small as a few hundred atoms -- and the behavior of long-chain molecules such as DNA.

Walsh has been given the 1998 Free Electron Laser Award by his peers, several thousand scientists around the world who work on free-electron physics. The work was reported in the January 19 issue of Physical Review Letters and in the May 8 issue of Science.

Free-electron lasers (FELs) are large-scale laser sources that were developed largely through programs such as the Strategic Defense Initiative and more recently through the Medical Free Electron Laser Initiative, a Department of Defense program intended to broaden the applications of FELs.

When Walsh began working on developing a compact, efficient FEL device about ten years ago, the equipment for generating the million electron-volt beams required by the conventional approach to FEL design could occupy a five-story building. In the version developed at Dartmouth, "the mechanism for producing a coherent beam could fit in the palm of your hand," says Walsh. "It's now a just a matter of time and engineering to adapt power supplies developed for other tasks -- such as flat panel displays -- to produce a device no bigger than a deck of cards.The compact size will allow the probe to be brought to the problem rather than the problem to the probe."

The potential uses of a portable device are enormous. A unit could be used to increase the sensitivity of far infrared telescopes by many orders of magnitude and could do the same for satellite-borne sensors that detect changes in the atmosphere. Says Dartmouth senior researcher Hayden Brownell, "This is rather like producing the PC version of the old room-sized NEAC computers. Putting this kind of technology into more hands is bound to result in all kinds of new applications."

The prototype developed by the Dartmouth team made inexpensive modifications to a scanning electron microscope, enabling it to send a beam of electrons at velocities near the speed of light across a grooved metal plate -- a laser-producing technique called the Smith-Purcell effect. The resulting electromagnetic coupling causes the speeding electrons to emit wavelets of energy in the form of infrared light -- not unlike the way sound waves are produced by running a stick across a picket fence.

Simultaneously sending a dense beam carrying multiple electrons across the grating has a synergistic effect, as the peaks of the waves reinforce each other. The result is a bright, coherent beam of radiation in the far infrared frequency range, a part of the electromagnetic spectrum lying well beyond the wavelength visible to the human eye. Changing the voltage, the angle of the grating or the spacing between the grooves all change the frequency of the radiation that is produced -- allowing the researchers to tune the device to the frequency desired.

"Reaching this kind of a research goal is always a team effort," says Walsh. "We have been engaged in free-electron laser research for nearly 25 years and many tens of students, research staff and scientific visitors have left their marks."

Significant members of the research team include John Urata, who was the the graduate student who first observed that the device had succeeded in producing a coherent beam, and Michael Goldstein, a doctoral student who first observed spontaneous emission from the device, both now at Intel, Inc.; Dartmouth Adjunct Professor and University of Essex Emeritus Professor of Physics Maurice Kimmitt; and Senior Research Associates John Swartz and Hayden Brownell.

Vermont Photonics in Brattleboro, Vt., will produce the compact machine.


Story Source:

The above story is based on materials provided by Dartmouth College. Note: Materials may be edited for content and length.


Cite This Page:

Dartmouth College. "Yankee Ingenuity: Dartmouth Physicists Convert A Microcope Into A Free-Electron Laser." ScienceDaily. ScienceDaily, 12 November 1998. <www.sciencedaily.com/releases/1998/11/981112075829.htm>.
Dartmouth College. (1998, November 12). Yankee Ingenuity: Dartmouth Physicists Convert A Microcope Into A Free-Electron Laser. ScienceDaily. Retrieved September 22, 2014 from www.sciencedaily.com/releases/1998/11/981112075829.htm
Dartmouth College. "Yankee Ingenuity: Dartmouth Physicists Convert A Microcope Into A Free-Electron Laser." ScienceDaily. www.sciencedaily.com/releases/1998/11/981112075829.htm (accessed September 22, 2014).

Share This



More Matter & Energy News

Monday, September 22, 2014

Featured Research

from universities, journals, and other organizations


Featured Videos

from AP, Reuters, AFP, and other news services

Raw: SpaceX Rocket Carries 3-D Printer to Space

Raw: SpaceX Rocket Carries 3-D Printer to Space

AP (Sep. 22, 2014) — A SpaceX Rocket launched from Cape Canaveral, carrying a custom-built 3-D printer into space. NASA envisions astronauts one day using the printer to make their own spare parts. (Sept. 22) Video provided by AP
Powered by NewsLook.com
Thousands March in NYC Over Climate Change

Thousands March in NYC Over Climate Change

AP (Sep. 21, 2014) — Accompanied by drumbeats, wearing costumes and carrying signs, thousands of demonstrators filled the streets of Manhattan and other cities around the world on Sunday to urge policy makers to take action on climate change. (Sept. 21) Video provided by AP
Powered by NewsLook.com
What This MIT Sensor Could Mean For The Future Of Robotics

What This MIT Sensor Could Mean For The Future Of Robotics

Newsy (Sep. 20, 2014) — MIT researchers developed a light-based sensor that gives robots 100 times the sensitivity of a human finger, allowing for "unprecedented dexterity." Video provided by Newsy
Powered by NewsLook.com
MIT BioSuit A New Take On Traditional Spacesuits

MIT BioSuit A New Take On Traditional Spacesuits

Newsy (Sep. 19, 2014) — The MIT BioSuit could be an alternative to big, bulky traditional spacesuits, but the concept needs some work. Video provided by Newsy
Powered by NewsLook.com

Search ScienceDaily

Number of stories in archives: 140,361

Find with keyword(s):
 
Enter a keyword or phrase to search ScienceDaily for related topics and research stories.

Save/Print:
Share:  

Breaking News:
from the past week

In Other News

... from NewsDaily.com

Science News

Health News

Environment News

Technology News



Save/Print:
Share:  

Free Subscriptions


Get the latest science news with ScienceDaily's free email newsletters, updated daily and weekly. Or view hourly updated newsfeeds in your RSS reader:

Get Social & Mobile


Keep up to date with the latest news from ScienceDaily via social networks and mobile apps:

Have Feedback?


Tell us what you think of ScienceDaily -- we welcome both positive and negative comments. Have any problems using the site? Questions?
Mobile iPhone Android Web
Follow Facebook Twitter Google+
Subscribe RSS Feeds Email Newsletters
Latest Headlines Health & Medicine Mind & Brain Space & Time Matter & Energy Computers & Math Plants & Animals Earth & Climate Fossils & Ruins