Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Terahertz imaging goes the distance

30.04.2007
News from the Conference on Lasers and Electro-optics/Quantum Electronics Laser Science Conference

Terahertz (THz) radiation, or far-infrared light, is potentially very useful for security applications, as it can penetrate clothing and other materials to provide images of concealed weapons, drugs, or other objects. However, THz scanners must usually be very close to the objects they are imaging. Doubts have lingered over whether it is possible to use THz waves to image objects that are far away, because water vapor in air absorbs THz radiation so strongly that most of it never reaches the object to be imaged.

At the upcoming CLEO/QELS meeting in Baltimore, an MIT-Sandia team will demonstrate the first real-time THz imaging system that obtains images from 25 meters away. The technique takes advantage of the fact that there are a few "windows," or frequency ranges, of the terahertz spectrum that do not absorb water very strongly. The MIT-Sandia group designed a special, semiconductor-based device known as a "quantum cascade laser" that delivers light in one of these windows (specifically, around 4.9 THz). They shine this light through a thin target with low water content (for example, a dried seed pod), and a detector on the other side of the sample records an image.

A cryorefrigerator maintains the laser at a temperature of 30 Kelvin, where it produces 17 milliwatts of power (as opposed to the microwatts of power typical of pulsed terahertz sources) in order to provide enough terahertz radiation to obtain a decent image. Increasing the power of the lasers and sensitivity of the detectors can potentially enable imaging of thicker objects or imaging of the reflected light, which would be more practical for security applications. In addition, the development of high-operating-temperature quantum cascade lasers, which operate without the use of cryogenic materials, may also increase the availability of this approach. In the closer term, however, this approach may enable sensing of chemical residues or contaminants in the air.

Colleen Morrison | EurekAlert!
Further information:
http://www.osa.org
http://www.cleoconference.org

More articles from Power and Electrical Engineering:

nachricht Failures in power grids: Dynamically induced cascades
25.05.2018 | Technische Universität Dresden

nachricht Beyond the limits of conventional electronics: stable organic molecular nanowires
24.05.2018 | Tokyo Institute of Technology

All articles from Power and Electrical Engineering >>>

The most recent press releases about innovation >>>

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

Im Focus: Powerful IT security for the car of the future – research alliance develops new approaches

The more electronics steer, accelerate and brake cars, the more important it is to protect them against cyber-attacks. That is why 15 partners from industry and academia will work together over the next three years on new approaches to IT security in self-driving cars. The joint project goes by the name Security For Connected, Autonomous Cars (SecForCARs) and has funding of €7.2 million from the German Federal Ministry of Education and Research. Infineon is leading the project.

Vehicles already offer diverse communication interfaces and more and more automated functions, such as distance and lane-keeping assist systems. At the same...

Im Focus: Molecular switch will facilitate the development of pioneering electro-optical devices

A research team led by physicists at the Technical University of Munich (TUM) has developed molecular nanoswitches that can be toggled between two structurally different states using an applied voltage. They can serve as the basis for a pioneering class of devices that could replace silicon-based components with organic molecules.

The development of new electronic technologies drives the incessant reduction of functional component sizes. In the context of an international collaborative...

Im Focus: LZH showcases laser material processing of tomorrow at the LASYS 2018

At the LASYS 2018, from June 5th to 7th, the Laser Zentrum Hannover e.V. (LZH) will be showcasing processes for the laser material processing of tomorrow in hall 4 at stand 4E75. With blown bomb shells the LZH will present first results of a research project on civil security.

At this year's LASYS, the LZH will exhibit light-based processes such as cutting, welding, ablation and structuring as well as additive manufacturing for...

Im Focus: Self-illuminating pixels for a new display generation

There are videos on the internet that can make one marvel at technology. For example, a smartphone is casually bent around the arm or a thin-film display is rolled in all directions and with almost every diameter. From the user's point of view, this looks fantastic. From a professional point of view, however, the question arises: Is that already possible?

At Display Week 2018, scientists from the Fraunhofer Institute for Applied Polymer Research IAP will be demonstrating today’s technological possibilities and...

Im Focus: Explanation for puzzling quantum oscillations has been found

So-called quantum many-body scars allow quantum systems to stay out of equilibrium much longer, explaining experiment | Study published in Nature Physics

Recently, researchers from Harvard and MIT succeeded in trapping a record 53 atoms and individually controlling their quantum state, realizing what is called a...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

VideoLinks
Industry & Economy
Event News

In focus: Climate adapted plants

25.05.2018 | Event News

Save the date: Forum European Neuroscience – 07-11 July 2018 in Berlin, Germany

02.05.2018 | Event News

Invitation to the upcoming "Current Topics in Bioinformatics: Big Data in Genomics and Medicine"

13.04.2018 | Event News

 
Latest News

In focus: Climate adapted plants

25.05.2018 | Event News

Flow probes from the 3D printer

25.05.2018 | Machine Engineering

Less is more? Gene switch for healthy aging found

25.05.2018 | Life Sciences

VideoLinks
Science & Research
Overview of more VideoLinks >>>