Thursday, April 28, 2011

Terahertz pulsed scanning which is claimed to be 10,000 times more powerful

Powerful pulses of terahertz radiation (T-rays) could be used to probe the fine internal structure of materials at an unprecedented level of detail.
A team of researchers from France and the UK have built a T-ray laser that is around 10,000 times more powerful than any similar device and can emit in separate pulses rather than a continuous stream.
Terahertz radiation — which refers to the far-infrared and microwave portion of the electromagnetic spectrum — is an area of increasing interest to scientists and engineers.
The technology was first developed by astronomers for detecting cosmic T-rays, but in the past decade or so there has been considerable progress in producing and detecting T-rays from terrestrial sources.
Active systems that emit T-rays then detect and image the resulting absorption and reflection patterns are now commercially available, while passive systems that can detect endogenous T-rays from various objects are also under development.
The method used by the current team is based on quantum cascade lasers that use a semiconductor as an active medium. They devised a way of ‘mode locking’ the laser by modulating its bias current with a radio-frequency synthesiser. The result was a powerful train of laser pulses that could be detected as a spectral signature.
‘This opens up opportunities for imaging that are not possible with passive systems, since one can investigate how the pulse shape is changed or delayed after propagating through a material,’ said Leeds University’s Prof Edmund Linfield, who worked on the project.
Linfield told The Engineer that the new method could offer spectroscopy at an unprecedented level of detail, probing structures at the nanoscale.
‘If we know that an object has a specific absorption line at a given frequency, say a rotational line of a gas molecule, we can tune our source so that all the power is focused at or close to this absorption line.’
The team has essentially validated its method and will now begin testing with materials in the lab, although Linfield stresses that the field of T-rays is still an emerging one.
‘There is not the “right” or “best” way of generating and detecting terahertz radiation as yet — each system has its advantages and disadvantages, depending on the targeted application. 
‘It is going to be exciting watching the field develop over the next decade and seeing whether a single terahertz technology will become the market leader.’
Researchers from Denis Didercot University in Paris and the French National Centre for Scientific Research (CNRS) also worked on the project, which was supported by the EPSRC, as well as several European grants.


Read more: http://www.theengineer.co.uk/sectors/electronics/news/t-rays-could-probe-materials-at-unprecedented-level-of-detail/1008448.article#ixzz1KpqEwThT

Wednesday, April 27, 2011

French & British Researchers produce Terahertz pulses from quantum cascade laser

logo CNRS


Researchers from Denis Diderot University in Paris, the French National Centre for Scientific Research (CNRS) and the University of Leeds, have produced T-ray ‘pulses’ from a quantum cascade laser.
This is the first time that such a high-powered source of terahertz rays (T-rays) has been made to emit separate 'packets' of terahertz radiation, rather than one continuous T-ray beam.
The work, which is published online in Nature Photonics, could open up new ways for T-rays to image natural and synthetic materials.
The term 'T-rays' describes a band of radiation in the electromagnetic spectrum that falls between radio waves and visible light. T-rays can be used to detect impurities in chemical and biological materials, generating characteristic 'spectral fingerprints' that are used to identify different substances.
Researchers have recently become interested in a technique known as terahertz time-domain spectroscopy, a particularly sensitive way of probing materials using pulses of T-rays. Up until now, these pulses have been made using laser sources that generated very little power (around one millionth of a Watt).
In this latest work, Stefano Barbieri and colleagues from Paris, together with Edmund Linfield and Giles Davies from the University of Leeds' School of Electronic and Electrical Engineering harnessed the power of a quantum cascade laser (almost 10,000 times more powerful) to create a train of T-ray pulses.  They also devised a way of detecting the full pulse train - confirming that the technique could be used for probing materials.
Professor Edmund Linfield said: "The potential for T-rays to provide new imaging and spectroscopy techniques for a range of applications such as chemical and atmospheric sensing, or medical imaging, is immense.  This breakthrough provides a significant advance in the underpinning technology." 
The research was supported by the Délégation Générale pour l'Armement (contract no. 06.34.020), the National Agency for Research (ANR) (contract HI-TEQ), the UK Engineering and Physical Sciences Research Council (EPSRC), and the European Research Council programmes 'NOTES' and 'TOSCA'.
For further information:
Paula Gould, University of Leeds press office: Tel 0113 343 8059, email mailto:www.leeds.ac.uk/news/article/1690/p.a.gould@leeds.ac.uk

Tuesday, April 26, 2011

Large scale production of graphene made possible in Poland for transistors operating at Terahertz speeds

http://www.tastingpoland.com/blog/polish-discovery-graphene-production.html
The discovery can help to revolutionize computer market in the future. Poles are ahead of other groups of scientists around the world who work on methods of industrial production of graphene.
Graphene is an extraordinary material. It consists of a single layer of carbon atoms. It is several hundred times stronger than steel but bends. Conducts the current hundred times better than copper and much better than silicon, which is still a base of all systems used in electronics, including computers.

For the discovery of graphene’s properties, scientists Andre Geim and Novoselov Konstantin got a Nobel Prize in physics last year. However, graphene they had made was in a form of tiny flakes with an area of ​​tens of microns. This is not enough and the material was not suitable for commercial exploitation.
Polish scientists from Institute of Electronic Materials Technology, and from Department of Physics, University of Warsaw have overcamed this barrier and managed to devise a way to transfer the production of graphene from the laboratory to the factory scale. They used standard equipment being used for years for the manufacture of semiconductor structures. Success is reported in one of recent issues of NanoLetters journal.
- Our method allows to produce large areas of graphene of highest quality. It will be possible to fit more electronics on a small area – explains Prof. Jacek Baranowski – As a result, computers will be smaller, more fuel-efficient, and several hundred times faster.
According to professor new material is in advance of silicon, which electronic era is inevitably coming to an end. – In ten years miniaturization of silicon based systems will achieve an end and graphene will replace them – he says.
It is true that Americans have already found a way. But their proposal, based on the use of silicon carbide requires heating to extreme temperatures – over 1500 °C. This is a significant drawback from economical point of view.
Poles now work on graphene-based transistor, which should be ready next year. These devices will operate at frequencies of hundreds of terahertz, values inaccessible for silicon.
News from Rzeczpospolita newspaper. Prof. Baranowski was interviewed also by Rzeczpospolita

3-D Terahertz Cloaking,Green UV sterilization,and MEGa-rays for nuclear detection


Research to be presented at CLEO: 2011 highlights latest advances in laser science

 IMAGE: Close-up micrograph of the bump region of the Terahertz cloaking structure. The size variations in the holes, which extend through the entire structure, is a key feature that guides...
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WASHINGTON, April 26—The world's foremost researchers in laser science, optoelectronics and quantum optics will present their findings at the Conference on Lasers and Electro-Optics (CLEO: 2011), May 1 – 6 at the Baltimore Convention Center. The more than 1,700 presentations at the conference will cover areas from energy and biophotonics to ultrafast lasers and quantum communication. Below is a sampling of the premiere research that will be presented next week at CLEO: 2011 (www.cleoconference.org).
  • Green UV Sterilization: Switching on LEDs to Save Energy and the Environment
  • Nuclear Photonics: Gamma Rays Search For Concealed Nuclear Threats
  • 3-D Terahertz Cloaking
  • Full 3-D Invisibility Cloak in Visible Light
Green UV Sterilization: Switching on LEDs to Save Energy and the Environment
Ultraviolet light can safely sterilize food, water and medical equipment by disrupting the DNA and other reproductive molecules in harmful bacteria. Traditionally, mercury lamps have supplied this UV light, however mercury release from power generation and lamp disposal have generated discussion of harmful environmental impact. A potentially energy efficient and non-toxic alternative is the light-emitting diode, or LED, which can be made to emit at almost any desired wavelength. LEDs are also more rugged and operate at lower voltages than glass containing mercury bulbs. Thus, LEDs are more compatible with portable water disinfection units, which could also be solar-powered and used in situations where centralized facilities are not available, such as disaster relief. LEDs currently require a lot of electricity to produce UV light, but researchers from around the world are focused on improving this efficiency.
LEDs are semiconductor devices that operate in much the same way as the tiny elements on a computer chip. The difference is that some of the electrons flowing into an LED are captured and release their energy as light. Because these are solid materials rather than gas-filled bulbs, LEDs are more compact and durable than alternative light sources. The first commercial LEDs were small red indicator lights, but engineers have developed new materials that emit in a rainbow of colors. Nitride-based LEDs are the most promising for pushing beyond the visible into the ultraviolet. Some of these UV LEDs are already being used in the curing of ink and the testing for counterfeit money, but for sterilization, shorter wavelength light is required. These short wavelength, or "Deep UV" LEDs, present a number of technical challenges and are predominantly implemented in highly-specialized disinfection systems in industrial and medical applications, as well as other non-disinfection markets.
The Joint Symposium on Semiconductor Ultraviolet LEDs and Lasers at CLEO: 2011 will feature several talks addressing these challenges, while highlighting current efforts to improve the efficiency of nitride-based LEDs. Max Shatalov of Sensor Electronic Technology in Columbia, S.C., will report an improved design for making high-power UV LEDs that would be especially good for knocking out bacteria. From the birthplace of nitride (blue and white) LEDs, Motoaki Iwaya from Meijo University in Japan will describe a joint effort with Nagoya University to extend the range and improve the efficiency of UV LEDs.
The application of these UV LEDs is also being pursued in a related CLEO: 2011 session. Gordon Knight from Trojan Technologies in Canada will review advances in production of novel UV light sources, along with necessary validation procedures for verifying the operation of water disinfection systems in a one-hour tutorial.
Presentation JTuD1, "High Power III-Nitride UV Emitters," by Max Shatalov et al. is at 11 a.m. Tuesday, May 3.
Presentation JTuD2, "IQE and EQE of the nitride-based UV/DUV LEDs," by Motoaki Iwaya et al. is at 11:30 a.m. Tuesday, May 3.
Tutorial ATuD1, "Water and Air Treatment Using Ultraviolet Light Sources," by Gordon Knight is at 1:45 p.m. Tuesday, May 3.
Nuclear Photonics: Gamma Rays Search For Concealed Nuclear Threats
Gamma rays are the most energetic type of light wave and can penetrate through lead and other thick containers. A powerful new source of gamma rays will allow officials to search for hidden reactor fuel/nuclear bomb material.
These gamma rays, called MEGa-rays (for mono-energetic gamma rays), are made by using a beam of fast-moving electrons to convert laser photons (light at a lesser energy) into the gamma ray part of the spectrum. The incoherent gamma rays can be tuned to a specific energy so that they predominantly interact with only one kind of material. A beam of MEGa-rays, for example, might be absorbed by the nuclear fuel uranium-235 while passing through other substances including the more common (but less dangerous) isotope uranium-238. That sort of precision opens the door to "nuclear photonics," the study of nuclei with light. "It is kind of like tunable laser absorption spectroscopy but with gamma-rays," says Chris Barty of Lawrence Livermore National Laboratory, who will present on MEGa-rays at CLEO: 2011.
In the last couple of years, MEGa-ray prototypes have identified elements like lithium and lead hidden behind metal barriers. The next-generation of MEGa-ray machines, which should come on-line in a couple of years, will be a million times brighter, allowing them to see through thick materials to locate specific targets in less than a second.
Barty will present several MEGa-ray applications in use today and will describe the attributes of next-generation devices. Work is under way on a MEGa-ray technology that could be placed on a truck trailer and carried out into the field to check containers suspected of having bomb material in them. At nuclear reactors, MEGa-rays could be used to quickly identify how enriched a spent fuel rod is in uranium-235. They could also examine nuclear waste containers to assess their contents without ever opening them up. MEGa-ray technology might also be employed in medicine to track drugs that carry specific isotope markers.
Presentation ATuF2, "Mono-Energetic Gamma-rays (MEGa-rays) and the Dawn of Nuclear Photonics," by Chris Barty is at 4:30 p.m. Tuesday, May 3.
3-D Terahertz Cloaking
Invisibility appears to be the next possible advance in the use of Terahertz radiation in medicine, security, and communications.
A research team from Northwestern and Oklahoma State universities claims to be first to cloak a three-dimensional object from view in a broad range of Terahertz frequency light, which lies between infrared and microwaves. In the team's paper at CLEO: 2011, Cheng Sun of Northwestern describes how a rigid sponge-like cloaking structure less than 10 millimeters long on a side was built up in 220 layers, each precisely defined to vary the index of refraction and bend light to render invisible anything located beneath a shallow concave bump on the cloak's bottom surface. The group showed that both the physical geometry and the spectrographic signature of a chemical strip about the width of 10 human hairs disappeared when cloaked.
Despite its Harry Potter-like allure, concealing tiny objects from view is not the team's ultimate goal, Sun said. Rather, this latest demonstration shows that the new "transformation optics" principles and 3-D lithography techniques they used to make the cloak can also enable optical components for guiding, collimating, and focusing terahertz light in a variety of ways—in new medical and scientific diagnostic tools, airport security scanners, and data communication devices.
Presentation, CWA5, "Three-dimensional Terahertz Cloak," by Cheng Sun et al. is at 1:30 p.m. Wednesday, May 4.
EDITOR'S NOTE: High-resolution images and diagrams of the 3-D Terahertz cloak are available. Contact Angela Stark, astark@osa.org.
Full 3-D Invisibility Cloak in Visible Light
Watching things disappear "is an amazing experience," admits Joachim Fischer of the Karlsruhe Institute of Technology in Germany. But making items vanish is not the reason he creates invisibility cloaks. Rather, the magic-like tricks are attractive demonstrations of the fantastic capabilities that new optical theories and nanotechnology construction methods now enable.
This new area, called "transformation optics," as the item just above also showed, has turned modern optical design on its ear by showing how to manipulate light in ways long thought to be impossible. They promise to improve dramatically such light-based technologies as microscopes, lenses, chip manufacturing and data communications.
In his CLEO: 2011 talk , Fischer will describe the first-ever demonstration of a three-dimensional invisibility cloak that works for visible light—red light at a wavelength of 700 nm—independent of its polarization (orientation). Previous cloaks required longer wavelength light, such as microwaves or infrared, or required the light to have a single, specific polarization.
Fischer makes the tiny cloak—less than half the cross-section of a human-hair—by direct laser writing (i.e. lithography) into a polymer material to create an intricate structure that resembles a miniature woodpile. The precisely varying thickness of the "logs" enables the cloak to bend light in new ways. The key to this achievement was incorporating several aspects of a diffraction-unlimited microscopy technique into the team's 3-D direct writing process for building the cloak. The dramatically increased resolution of the improved process enabled the team to create log spacings narrow enough to work in red light.
"If, in the future, we can halve again the log spacing of this red cloak, we could make one that would cover the entire visible spectrum," Fischer added.
Practical applications of combining transformation optics with advanced 3-D lithography (a customized version of the fabrication steps used to make microcircuits) include flat, aberration-free lenses that can be easily miniaturized for use in integrated optical chips, and optical "black holes" for concentrating and absorbing light. If the latter can also be made to work for visible light, they will be useful in solar cells, since 90 percent of the Sun's energy reaches Earth as visible and near-infrared light.
Presentation QTuG5 "Three-dimensional invisibility carpet cloak at 700 nm wavelength," by Joachim Fischer et al. is at 11 a.m. Tuesday, May 3. Fischer et al. will also present CML1, "Three-Dimensional Laser Lithography with Conceptually Diffraction-Unlimited Lateral and Axial Resolution," at 10:15 a.m. Monday, May 2.
###
CLEO: 2011 Program Information
CLEO: 2011 unites the fields of lasers and optoelectronics by bringing together all aspects of laser technology, from basic research to industry applications. The main broad topics areas at the meeting are fundamental science, science and innovations, applications and technology, and market focus. An exposition featuring 300 participating companies will be held concurrently with the scientific presentations.
Plenary Session keynote speakers include Donald Keck, retired vice president of Corning, talking about making the first low-loss optical fibers; James Fujimoto of MIT, talking about medical imaging using optical coherence tomography (OCT); Mordechai (Moti) Segev of the Technion-Israel Institute of Technology, speaking about the localization of light; and Susumu Noda of Kyoto University, talking about the control of photons in photonic crystals.
Online resources:
Press Registration
A Press Room for credentialed press and analysts will be located on-site in the Baltimore Convention Center, Sunday, May 1 – Thursday, May 5. Media interested in attending the conference should register online athttp://www.cleoconference.org/media_center/mediaregistrationform.aspx or contact Angela Stark at 202.416.1443, astark@osa.org.
About CLEO
With a distinguished history as the industry's leading event on laser science, the Conference on Lasers and Electro-Optics (CLEO) and the Quantum Electronics Laser Science Conference (QELS) is where laser technology was first introduced. CLEO: 2011 will unite the field of lasers and electro-optics by bringing together all aspects of laser technology, with content stemming from basic research to industry application. Sponsored by the American Physical Society's (APS) Laser Science Division, the Institute of Electronic Engineers (IEEE) Photonics Society and the Optical Society (OSA), CLEO: 2011 provides the full range of critical developments in the field, showcasing the most significant milestones from laboratory to marketplace. With an unparalleled breadth and depth of coverage, CLEO: 2011 connects all of the critical vertical markets in lasers and electro-optics. For more information, visit the conference's website at www.cleoconference.org.

SPIE Defense, Security + Sensing 2011 Event News and Photos


IR Technologies and Applications
Strong first day in Orlando
Conferences saw strong attendance on opening day of SPIE Security, Defense, and Sensing, including more than 200 people in the room for sessions on Infrared Technologies and Applications where opening papers were from SOFRADIR, The Aerospace Corp., SCD Semicondcutor Devices, Thales Optronics, and others.
Paper 8012-1 ("Sofradir latest developments for infrared space detectors," byPhilippe ChorierPatricia PidancierYoanna-Reine Nowicki-Bringuier,Anne Delannoy, and Bruno Fieque of Sofradir) described how Sofradir develops and produces application-specific IR imaging systems for both tactical and space missions.
Current space applications include the Saturn imaging system at .4 to 2.5 microns with an array size of 1000x256 pixels. The system is rad-hardened and passed both shock and vibration testing for launch events. Other systems include the Neptune imaging system at 500x256 pixels and the Sentinel system for a European remote Sensing application.
The Sentinel system is designed specifically for monitoring vegetation and has a superspectral detector at 6 individual wavelengths. Each wavelength is in a 1298x1 detector array meant for a synthetic aperture optical approach. In 2011 Sofradir will have 5 imaging systems launched into orbit.
Active target tracking advances were described in paper 8052-01, "Requirements on active (laser) tracking and imaging from a technology perspective," by Jim Riker (Air Force Research Lab). The technique employs a laser to illuminate the target and provide increased signal back to the detector.
The method has proved successful in the Airborne Laser program, the Airborne Tactical Laser program, and the Tactical High-Energy Laser program. Active tracking -- as compared to passive tracking which uses ambient sunlight -- improves the return signal-to-noise ratio, but its effectiveness is limited by the atmospheric variables, turbulence and spectral reflectance of the target. Thus future priorities are to improve detector technology.
In the keynote paper for the conference on Terahertz Physics, Devices, and Systems ("Toward realizing high-power semiconductor terahertz laser sources at room temperature," 8023-01) Manijeh Razeghi of Northwestern Univ. discussed the progress and varied approaches for reaching the goal of a compact, room-temperature, electrically driven, milliwatt terahertz (Thz) optical source.
Optical approaches include using quantum cascade lasers (QCL) in the far-infrared to generate Thz output or mixing the output from two far-spaced IR QCLs to generate a beat frequency in the Thz range in a nonlinear medium.
New Fellows
SPIE President Elect presented pins to new Fellows of the Society at a luncheon attended by approximately 50 of the Society's Fellows. The 5 new Fellows out of 67 named by SPIE this year who are being honored this week are:
  • Susan Davis Allen, Arkansas State University
  • Fredric Marvin Ham, Florida Institute of Technology
  • Sanjay Krishna, Center for High Technology Materials
  • Kalluri Sarma, Honeywell Technology
  • Alexander Toet, TNO Defence Security and Safety.
Luncheon speaker SPIE Fellow Larry Stotts of DARPA (below) told why free space optical communication and submarine laser communication have come under serious consideration.
Larry Stotts
Reception celebrates imaging hallmarks, unmanned vehicles
The well-attended all-symposium welcome reception treated attendees to two technology demonstrations -- one long-standing and one cutting-edge. An imaging gallery sponsored by StingRay and SPIE featured the infrared, high-speed, and other technologies on which SPIE was originally founded, with entries ranging from professional applications to artistic renditions. Inside the reception hall, FLIR offered attendees a chance to race unmanned vehicles around an obstacle course.

Monday, April 25, 2011

Herschel Astrophysical Terahertz large Area Survey looks at evolution of dust in galaxies

The Herschel Space Observatory has been used to help astronomers at Cardiff, Nottingham University and Max-Planck Institute for Astrophysics to understand the amount of dust in galaxies at varying distances, it was heard at the National Astronomy Meeting held in Llandudno, North Wales, last week.
Dr Haley Gomez of Cardiff University, who presented the results at the conference, along with her colleagues, used data taken from the Herschel Astrophysical Terahertz large Area Survey, H-ATLAS, to take a look at the evolution of dust in galaxies over the past five billion years of cosmic history. H-ATLAS is the largest key astronomical project on ESA’s Herschel Space Observatory and surveys an amazing 550 square degrees of sky. With both its PACS and SPIRE cameras which snap pictures in the infrared and submillimetre wavebands, astronomers are able to unveil the cold Universe, studying the dusty cosmos in high detail. To tell us more about dust and Herschel, Astronomy Now reporter Gemma Lavender interviews Cardiff University’s Dr Haley Gomez in the video report below.
Now, the survey has provided Gomez and her team with an insight into the Universe, where they found that the galaxies they studied were dominated by cold dust with temperatures between 15 to 25 kelvin (–258 to –248 degrees Celsius). Their observations also revealed that the dust masses for large galaxies were about five times larger at redshifts of around 0.5 compared to galaxies which can be found in the local universe. The collaboration between the three institutions has also revealed that the mass of dust to stellar mass was three to four times larger in the past. The source of this interstellar dust is still uncertain and difficult to explain with standard models.
But why is this cold dust relevant? Dust contributes one percent of the mass of a galaxy but despite this small amount, it allows stars to form more efficiently. Without these cosmic particles, we would not have molecular hydrogen, which means no water traces in galaxies. “We’re talking about the building blocks of asteroids, the cores of comets and rocky planets,” says Gomez. “But we’re also talking about the building blocks of us – life is lumps of dust, of iron and carbon and so on, inside ourselves. So when you ask where dust comes from you’re asking where planets come from and where life comes from.”

Saturday, April 23, 2011

Focus on Zomega Terahertz Corporation



Recently, I've been fortunate to establish communication with Thomas Tongue, the CEO at Zomega Corporation, http://www.zomega-terahertz.com/. Thomas's bio, on the webpage, notes the following:
"With over twelve years of entrepreneurial and management experience, and a strong technical background founded in his Masters degree in Physics, Thomas bridges the gap between the technical potential of terahertz imaging and the market. His prior start-up experience includes co-founding Imagiware, Inc., an Internet solution provider focusing on web presence and software development, which he bootstrapped to profitability by mid-1996. Thomas earned his MBA from the Lally School of Management & Technology at Rensselaer Polytechnic Institute."


In responding to questions about Zomega, Tom writes:

"Hi Randy,
We recently opened a new section of our web site dedicated to THz Imaging which has some materials I think will be of general interest. This is in support of our Teracopia project whose primary goal is to distribute THz imaging data and supporting software under a Creative Commons license so that people can start to think about how to use this powerful new tool and what sort of data processing challenges are involved (they're non-trivial). So I'd invite you to have a look around that section and let me know what questions you might have."

The Teracopia project is found on the company webpage, here: http://www.zomega-terahertz.com/index.php?option=com_content&view=article&id=62&Itemid=60
Interesting material, and if some of you have specific questions, please post or send them to me, and I'll see if I can get Tom to answer some of them.

understood Tom's email to also express that he views the current state of THz  market development, (in this very early stage), to be one where the various THz companies, are not usually  in direct competition, but rather are creating specific tools for particular niches. Hence my understanding is, he didn't believe it would be helpful, or practical to compare differing applications because each system is employed in a particular context, which makes overall comparison difficult. I had a sense, that he views the THz community in a very " fraternal sense", and given the many years of struggle to bring  THz from the laboratory to practical/commercial use, I understand why this sense of  comradery would be present.

                       Zomega Terahertz Corporation - December 2010 - Front: Wendy Zhang, Dr. X.-C. Zhang, Thomas Tongue; Back: Dr. Ying Xu, Scott Stewart, Joshua Hernandez, Dr. Brian Schulkin, Justin St. James, Dr. Norman Laman, Dr. Chia-Chu Chen, Erick Tejada

Here's wishing Thomas Tongue, and the creative engineers and scientists working there the greatest success!
And thanks to Thomas for sharing a few thoughts with me, and you.

Friday, April 22, 2011

Stratospheric Terahertz Observatory



Columbia Scientific Balloon Facility LogoImage via Wikipedia
MY NOTE: THIS IS NOT A NEW STORY, BUT NEW TO ME, AND IT'S VERY INTERESTING. I DIDN'T KNOW THIS WAS GOING ON IN MY CORNER OF THE WORLD.

Details of the balloon and launch operations

Launch site: Scientific Flight Balloon Facility, New Mexico, US  
  Launch team: CSBF (Columbia Scientific Balloon Facility) Balloon: Open balloon (zero pressure) Volume:   Serial number: -Flight identification number: 603N Campaign: No Data
Payload weight: - Gondola weight: -Overall weight: -
The balloon was launched by dynamic method using the Big Bill launch vehicle at 16:00 utc on October 15. After a nominal climbing phase it reached float altitude of 125.000 ft. at 18:05 utc starting a drifting route mainly to the northwest. At right can be seen the complete trajectory of the balloon (click to enlarge).

The flight endured until 6:25 utc of October 16 when the payload was separated from the balloon, landing 42 kms. West of Santa Rosa, New Mexico.

The total flight time was near 14 hours.


Description of the payload or experiment

STO (Stratospheric Terahertz Observatory)

Responsable institution:  University of Arizona / Johns Hopkins University Applied Physics Lab / NASA AMES Research Center / Jet Propulsion Laboratory / California Institute of Technology / Oberlin College / University of Maryland / Universitaet zu Koeln (Germany)
Principal Investigator:  Dr. Christopher K.Walker

The Stratospheric Terahertz Observatory (STO) is a NASA-funded long duration balloon (LDB) experiment designed to address a key problem in modern astrophysics: understanding the life cycle of star-forming molecular clouds in our Milky Way Galaxy.

To accomplish this goal, STO will survey a section of the Galactic Plane in the luminous interstellar cooling line at 158 microns (1.90 THz) and the important star-formation and ionized gas tracer at 205 microns (1.45 THz). The 4-pixel heterodyne receiver arrays on board STO possess the sensitivity and spectral resolution needed to see molecular clouds in the process of formation, measure the rate of evaporation of molecular clouds and separate the bulk motion of gas in our Galaxy from local kinematic effects. STO's 0.8m telescope provides ~1' spatial resolution, providing more than two orders of magnitude improvement in spatial resolution over existing data. By building a three-dimensional picture of the interstellar medium of the Galaxy, STO will be able to study the creation and disruption of star-forming clouds in the Galaxy, determine the parameters that govern the star formation rate, and provide a template for star formation and stellar/interstellar feedback in other galaxies.

STO is conformed by a telescope, eight heterodyne receivers (four for each line to be observed) , an eight-channel Fieldable Fourier Transform Spectrometer System , control electronics , an hybrid He cryostat, and a precision gondola. At left can be seen a scheme of the STO in full configuration.

STO uses the same telescope that Johns Hopkins University Applied Physics Laboratory has previously employed for its successful Flare Genesis Experiment (FGE). The primary mirror is an 80-cm diameter, f/1.5 hyperboloid made of Ultra Low Expansion titanium silicate glass (ULE), and honeycombed to a weight of just 50 kg. Its surface is polished to visible-band optical quality, therefore over-specified for imaging in the 100 to 200 micron wavelength range. Its support and spider arms are made of light weight graphite-epoxy, which provides high thermal stability over a wide range of temperatures. A tertiary chopper is located near the backside of the main mirror on a counterbalanced mount to minimize reaction forces. A calibration box located between the telescope and the receiver cryostat places blackbody loads at known temperatures in the path of the detectors for comparison, allowing to determine the detector noise, the telescope efficiency, the opacity of the atmosphere and the absolute flux of astronomical sources.

The receivers are fed by the beam entering the telescope which first encounters a free-standing wire grid that divides the incident light into horizontal and vertical polarization components. One polarization passes through the grid into the first vacuum window while the other reflects off a 45º mirror and enters a second vacuum window. The vacuum windows and subsequent 77, 25, and 4K IR filters are made from low-loss, AR coated, single crystal quartz. The first flight receiver will consist of two, orthogonally polarized 1x4 arrays of superconductive hot-electron bolometer (HEB) mixers operating at 4º Kelvin. One array optimized for the 1.90 THz line and the other for the 1.46 THz line. The mixers will be pumped by two, frequency tunable, solid-state Local Oscillators (LO's).

A flight instrument electronics box houses several boards that control the spectrometer, the LO/HEB/LNA bias board, the calibration flip mirror, and the instrument computer.

To cool the mixer arrays, STO uses a 200 liter liquid helium cryostat. An off-the-shelf mechanical refrigerator cools the first radiation shield to 77K while the second one will be vapor-cooled to 25K.

STO will rely entirely on the NASA-CSBF provided remote link to/from the gondola for the communications between the experiment and the ground. For the long duration balloon mission in Antarctica that will be acomplished through the NASA's Tracking and Data Relay Satellite System (TDRSS) while in the moment that the balloon traverses a zone where none of the TDRSS satellites are in view, a backup link using the Iridium satellite system will be available.

As occurred with the telesciçope, the gondola is inherited from the APL which developed it in the framework in the Flare Genesis and Solar Bolometric Imager balloon programs, that performed two test flights in New Mexico and three long duration balloon Antarctic flights. The structure carries and protects the telescope and instrument, the command and control systems, and the power system. Its basic dimensions (without solar arrays) are: 2m wide, 1.5m deep, and 4.5m high. The frame is made of standard aluminum angles bolted together and painted with a white thermal coating. The structure is strong enough to support up to 2000 kg even under the 10 g shock experienced at the end of the flight when the parachute inflates. It is rigid enough to allow the required telescope pointing stability. The gondola can be separated into lighter components for easy post-flight retrieval in the field.


Performance in flight and data obtained


This engineering prototype of STO was planned to be performed in CONUS with a flight duration less than 24 hours. The instrument configuration consisted of a liquid helium dewar supporting operation of an HEB mixer in each of the 1.4 and 1.9 THz bands, in addition to an ambient-temperature Schottky receiver operating at 330 GHz.

The first scientific flight of the instrument in the full fledged configuration will take place in the Long Duration Balloon campaign to be held at McMurdo Antarctica in end 2010, begin 2011.


External references and bibliographical sources









THE FOLLOWING PDF IS A MORE RECENT DESCRIPTION OF THIS WORK.
http://www.jhuapl.edu/techdigest/TD/td2803/20Bernasconi.pdf

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Thursday, April 21, 2011

Northrop Grumman awarded 12 million dollar Terahertz development contract by DARPA

Logo of the Defense Advanced Research Projects...Image via Wikipedia





http://www.defpro.com/news/details/23907/


Northrop Grumman Space & Mission Systems, Redondo Beach, Calif., is being awarded a $12,523,315 modification to a cost-plus-fixed-fee contract (HR0011-09-C-0062). This award is for the Terahertz (THz) Electronics Program. The contractor shall develop critical device and integration technologies necessary to realize compact, high-performance electronic circuits that operate at a center frequency of 1.03 THz. Work will be performed in Redondo Beach, Calif. (82.58 percent); Charlottesville, Va. (1.84 percent); Pasadena, Calif. (9.38 percent); Charlottesville, Va. (3.51 percent); Tempe, Ariz. (1.73 percent); and University Park, Pa. (0.96 percent). The work is expected to be completed April 16, 2014. The Defense Advanced Research Projects Agency is the contracting activity.

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Tuesday, April 19, 2011

Terahertz emission reveals optical rectification and possible solar power without solar cells

Experiments such as this one with high-power l...Image via Wikipedia


MY NOTE: THIS INTERESTING ARTICLE HAS BEEN ON THE NET THE LAST WEEK. LIKE SOME OTHER RECENT POSTS I'VE INCLUDED, IT'S NOT DIRECTLY RELATED TO  THz,  SCANNING, BUT MAY PORTEND ANOTHER FUTURE AREA OF THz INNOVATION. 
Released: 4/19/2011 4:45 PM EDT
Source: University of Michigan

Newswise — ANN ARBOR, Mich.---A dramatic and surprising magnetic effect of light discovered by University of Michigan researchers could lead to solar power without traditional semiconductor-based solar cells.
The researchers found a way to make an "optical battery," said Stephen Rand, a professor in the departments of Electrical Engineering and Computer Science, Physics and Applied Physics.
In the process, they overturned a century-old tenet of physics.
"You could stare at the equations of motion all day and you will not see this possibility. We've all been taught that this doesn't happen," said Rand, an author of a paper on the work published in the Journal of Applied Physics. "It's a very odd interaction. That's why it's been overlooked for more than 100 years."
Light has electric and magnetic components. Until now, scientists thought the effects of the magnetic field were so weak that they could be ignored. What Rand and his colleagues found is that at the right intensity, when light is traveling through a material that does not conduct electricity, the light field can generate magnetic effects that are 100 million times stronger than previously expected. Under these circumstances, the magnetic effects develop strength equivalent to a strong electric effect.
"This could lead to a new kind of solar cell without semiconductors and without absorption to produce charge separation," Rand said. "In solar cells, the light goes into a material, gets absorbed and creates heat. Here, we expect to have a very low heat load. Instead of the light being absorbed, energy is stored in the magnetic moment. Intense magnetization can be induced by intense light and then it is ultimately capable of providing a capacitive power source."
What makes this possible is a previously undetected brand of "optical rectification," says William Fisher, a doctoral student in applied physics. In traditional optical rectification, light's electric field causes a charge separation, or a pulling apart of the positive and negative charges in a material. This sets up a voltage, similar to that in a battery. This electric effect had previously been detected only in crystalline materials that possessed a certain symmetry.
Rand and Fisher found that under the right circumstances and in other types of materials, the light's magnetic field can also create optical rectification.
"It turns out that the magnetic field starts curving the electrons into a C-shape and they move forward a little each time," Fisher said. "That C-shape of charge motion generates both an electric dipole and a magnetic dipole. If we can set up many of these in a row in a long fiber, we can make a huge voltage and by extracting that voltage, we can use it as a power source."
The light must be shone through a material that does not conduct electricity, such as glass. And it must be focused to an intensity of 10 million watts per square centimeter. Sunlight isn't this intense on its own, but new materials are being sought that would work at lower intensities, Fisher said.
"In our most recent paper, we show that incoherent light like sunlight is theoretically almost as effective in producing charge separation as laser light is," Fisher said.
This new technique could make solar power cheaper, the researchers say. They predict that with improved materials they could achieve 10 percent efficiency in converting solar power to useable energy. That's equivalent to today's commercial-grade solar cells.
"To manufacture modern solar cells, you have to do extensive semiconductor processing," Fisher said. "All we would need are lenses to focus the light and a fiber to guide it. Glass works for both. It's already made in bulk, and it doesn't require as much processing. Transparent ceramics might be even better."
In experiments this summer, the researchers will work on harnessing this power with laser light, and then with sunlight.
The paper is titled "Optically-induced charge separation and terahertz emission in unbiased dielectrics." The university is pursuing patent protection for the intellectual property.
For more information:
Stephen Rand: http://www.eecs.umich.edu/OSL/Rand/
U-M Sustainability fosters a more sustainable world through collaborations across campus and beyond aimed at educating students, generating new knowledge, and minimizing our environmental footprint. Learn more atsustainability.umich.edu

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Far Sighted Space Technology Finds Practical Uses On Earth



http://nanopatentsandinnovations.blogspot.com/2011/04/far-sighted-space-technology-finds.html

Technology developed for space missions to study the most distant objects in the Universe is now finding a host of practical applications back on Earth. QMC Instruments Ltd., in partnership with the Astronomical instrumentation Group at Cardiff University, has built instruments for many major space missions, including Herschel and Planck. Now, expanding on that experience they are developing KIDCAM, a kind of detector that could have applications in hospitals, factories and airports. Ken Wood will present the project at the RAS National Astronomy Meeting in Llandudno, Wales, on Tuesday 19th April.

QMC Instruments Ltd was involved in the design and manufactured the Corrugated horns for the HFI Instrument on Planck, ESA's Space based Cosmic Microwave Background experiment.
Credit: TK Instruments

The part of the Electromagnetic Spectrum including the far infra red and microwave is also called 'terahertz' radiation. Astronomers use this kind of radiation to study the Cosmic Microwave Background and the huge dust clouds where stars are born. The sensitive detectors they use will only operate at temperatures very close to absolute zero (minus 273C.) In Terahertz cameras like KIDCAM, those low temperatures are accessible in compact and less expensive ways using relatively new cooler technology. KIDCAM therefore has many potential day-to-day applications.

QMC Instruments Ltd was involved in the design and manufactured the Corrugated horns for the HFI Instrument on Planck, ESA's Space based Cosmic Microwave Background experiment.
Credit: ESA (Image by AOES Medialab)

"We are all familiar with optical images of the surface of objects and X-ray images which penetrate through soft tissue to reveal bone structure. Terahertz observations give us something in between the two. For example, most clothing and packaging materials are transparent to Terahertz radiation, whereas skin, water, metal and a host of other interesting materials are not. This gives rise to some important day-to-day applications: detecting weapons concealed under clothing or inside parcels; distinguishing skin and breast cancer tissue; quality control of manufactures items and processes in factories. Our KIDCAM detectors are also very sensitive, and so we can look at the natural radiation emitted by the target. This means there are no safety issues like those associated with other imaging techniques which shine radiation, including X-rays, at the target," said Mr Wood.

Until recently, there have been many practical obstacles to using terahertz detectors. Terahertz sources have only become available to the non-specialist in the last 10 years and cooling the detectors to very low temperatures using liquid cryogens is costly and complicated.

The Herschel and Planks satellites are used by astronomers to map the furthest reaches of the Universe. UK business partnerships could soon ensure that similar technology is used back on Earth to keep our airports secure or diagnose breast cancer.
Credit: ESA (Image by AOES Medialab)

"The instruments aboard the Herschel and Planck satellites need to be cooled to temperatures close to absolute zero so that emissions from the spacecraft don’t drown out the faint signals that come from the very edge of the observable Universe," said Ken Wood.

"For KIDCAM, we have developed a kind of detector that can be operated in electrical coolers and therefore without the use of liquified gases. KIDCAM can be tuned to specific frequencies for specific applications, for instance to, enhance the contrast between skin and plastic explosive for airport security scanners. Unwanted frequencies can be blocked to increase the camera’s sensitivity. The experience that we gained working on astronomical missions has been invaluable in helping us do this. The race is now on around the world to produce devices that will realise the enormous potential of terahertz science and thanks to the ingenuity of UK astronomers we have made a great start."

Source: Royal Astronomical Society