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Topic: Terahertz radiation

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	Reference.com/Encyclopedia/Terahertz radiation
		Terahertz radiation is non-ionizing and shares with microwaves the capability to penetrate a wide variety of non-conducting materials.
		The Terahertz Photonics and Electronics research group at the Institute of Microwaves and Photonics at the University of Leeds in the United Kingdom is one of the main centres of research into uses of Terahertz radiation.
		While terahertz radiation is emitted as part of the fl body radiation from anything with temperatures greater than about 10 kelvin, this thermal emission is very weak.
	www.reference.com /browse/wiki/Terahertz_radiation (1095 words)

	Time-resolved Terahertz spectroscopy
		Because the wavelength of terahertz radiation is much longer than that of visible light, it is not possible to create narrow beams such as those from a laser.
		Instead, the terahertz beam, which has a diameter of 2 mm at the point where it is generated, diverges strongly, and a large mirror is needed to capture all the radiation.
		In time-resolved terahertz spectroscopy, the terahertz pulses described above are used as probe pulses to probe the state of a sample after excitation by a pump pulse of visible light.
	www.chemphys.lu.se /kfresearch/fac-trts.html (1019 words)

	Terahertz radiation: applications and sources - The Industrial Physicist
		Terahertz radiation can also help scientists understand the complex dynamics involved in condensed-matter physics and processes such as molecular recognition and protein folding.
		CW terahertz technology has long interested astronomers because “approximately one-half of the total luminosity and 98% of the photons emitted since the Big Bang fall into the submillimeter and far-infrared,”; says Peter Siegel of the Jet Propulsion Laboratory (Pasadena, CA), and CW THz sources can be used to help study these photons.
		Although the practical application of terahertz radiation is in its infancy, the recent availability of reliable sources in the 0.3- to 5-THz range may have a wide-ranging impact on science, industry, and medicine.
	www.aip.org /tip/INPHFA/vol-9/iss-4/p27.html (2034 words)

	Terahertz Imaging
		The first imaging device based on terahertz radiation was introduced in 1995 by Hu and Nuss.
		These waves, known as terahertz radiation, are in a waveband that is the overlap of what is normally regarded as microwave radiation and far-infrared light.
		However, recent technologies using terahertz radiation have been developed, which are intended for applications such as medical imaging and surveillance.
	pami.uwaterloo.ca /tizhoosh/terahertz_imaging.htm (175 words)

	Terahertz waves penetrate the world of imaging - optics.org
		Terahertz waves are electromagnetic waves that have a frequency of between 100 GHz and 30 THz and lie between the infrared and microwave parts of the spectrum.
		To date, terahertz waves are usually generated by illuminating a piece of semiconductor, such as gallium arsenide, with femtosecond pulses from a solid-state laser such as a Ti:sapphire laser.
		Coherent detection of the pulses is achieved by illuminating a second crystal with both the terahertz pulses and a portion of the visible femtosecond pulses that is split off from the original beam and has undergone a suitable time delay.
	optics.org /articles/ole/7/9/5/1 (1788 words)

	Terahertz breakthrough at BESSY (March 2003) - News - PhysicsWeb
		Terahertz radiation can be used in applications as diverse as biological imaging and the study of semiconductors.
		Synchrotron radiation is produced when bunches of charged particles, usually electrons that have been accelerated to close to the speed of light, are forced to move in a circular orbit by strong magnetic fields.
		Terahertz radiation is found at the low-energy end of the spectrum and corresponds to wavelengths between about 1 mm and 15 microns.
	www.physicsweb.org /article/news/7/3/9 (332 words)

	ESA Portal - Space camera blazes new terahertz trails
		Terahertz waves occupy a portion of the spectrum between infrared and microwaves, from 10¹¹ to 10¹³ Hertz.
		However, terahertz waves are very interesting as they possess characteristics of both their neighbours: terahertz waves can pass easily through some solid materials, like walls and clothes, yet can be focused as light to create images of objects.
		The main advantage of a terahertz imager is that it does not emit any radiation; it is a passive camera capturing pictures of the natural terahertz rays emitted by almost everything, including people, rocks, water, trees and stars.
	www.esa.int /export/esaCP/SEMZ1R1A6BD_index_0.html (1628 words)

	Terahertz - Wikipedia, the free encyclopedia
		Also known as T-rays, terahertz waves sit on the electromagnetic spectrum between infrared and microwaves, and they exhibit a range of properties that make them particularly attractive.
		Terahertz waves have been touted as the next big thing for security and communication devices.
		While terahertz are useless for long-range communications because they are so easily absorbed by atmospheric water, the improvements in speed and bandwidth they offer make it almost inevitable that terahertz will be used for short-range communications.
	en.wikipedia.org /wiki/Terahertz (499 words)

	Microwave Engineering Online - Micromachine technique creates terahertz sensor (Site not responding. Last check: 2007-10-12)
		Silicon micromachined structures that reject photons in certain terahertz bands have been demonstrated in the project, which aims to use the effect to fashion optical components for terahertz radiation.
		Terahertz radiation, which occupies a region of the spectrum between infrared and radar, has recently become interesting for a variety of applications including medical-imaging projects, airport security systems, astronomy and earth-viewing satellites.
		The technological challenge is to build complex silicon structures at dimensions comparable with the wavelength of the terahertz radiation, which ranges from 1 mm to 10 microns.
	www.mwee.com /mwee_news/OEG20020812S0040 (664 words)

	RPI Center for Terahertz Research - About Us
		Using the relatively unexplored terahertz portion of the electromagnetic spectrum, they are creating innovative imaging and sensing technologies that hold enormous potential in biomedical imaging, genetics diagnostics, microelectronics, and the chemical and biological materials identification fields.
		The center's four labs are equipped with the most advanced photonic and opto-electronic instrumentation for generating, measuring, and recording picosecond and femtosecond terahertz radiation waves.
		Rensselaer's Center for Terahertz Research stands at the forefront of terahertz technology, a science still in its infancy yet expected to become one of the most promising research areas for transformational imaging in the 21st century.
	www.rpi.edu /terahertz/about_us.html (712 words)

	Terahertz Systems
		Abstract: When terahertz radiation propagates in an ionic crystal the electromagnetic field couples to the phonon modes of the crystal resulting in an admixture of photons and phonons known as phonon-polaritons.
		Terahertz radiation (T-rays) can penetrate clothing and, to some extent, can also penetrate biological materials, and because of their shorter wavelengths they offer higher spatial resolution than microwaves or millimeter waves.
		However, development of terahertz technologies is impeded or even prevented by the lack of standards and the inability to perform precise measurements to characterize noise, power, dielectric constants, and scattering parameters of systems and components operating at terahertz frequencies.
	www.ieeeboston.org /edu05s/2005fall/terahertz_systems.htm (4044 words)

	Handheld terahertz wand to unmask terrorists - 12 July 2004 - New Scientist (Site not responding. Last check: 2007-10-12)
		But using terahertz radiation to produce X-ray-like images of passengers is likely to be unacceptable for routine use, as it will allow security staff to see the people they are scanning as if they were naked.
		Terahertz waves occupy a relatively unexplored part of the electromagnetic spectrum between microwaves and infrared.
		Instead, the system will check to see which wavelengths of terahertz radiation have been absorbed and reflected by the subject and pick up the characteristic spectral signatures of explosives, metals and other chemicals such as drugs.
	www.newscientist.com /article.ns?id=dn6118 (502 words)

	Coherent Terahertz Synchrotron Radiation
		When the wavelength of synchrotron radiation is comparable to the length of an electron bunch in the storage ring, or the length of any structure on the bunch, the radiation from multiple electrons is in phase, resulting in a quadratic rather than the usual linear dependence of the power emitted on the number of electrons.
		The interaction of an electron bunch and its synchrotron radiation begins when an electron bunch bends through a magnetic field and emits a cone of synchrotron radiation that has a transverse electromagnetic field.
		However, when the wavelength of the emitted radiation is comparable to the length of an electron bunch, the electrons emit in unison rather than as individuals.
	www-als.lbl.gov /als/science/sci_archive/61coherent.html (1036 words)

	Imaging with terahertz radiation
		Terahertz is an emerging research area that has flourished rapidly over the last decade.
		Terahertz radiation possesses a number of properties that makes it a promising radiation source for spectroscopy and imaging.
		Terahertz quantum cascade laser was experimentally realised for the first time in 2002, providing a new powerful source to generate terahertz radiation.
	www.cheng.cam.ac.uk /news/2006/terahertz.html (332 words)

	Terahertz radiation targets skin cancer - Advanced Physics Forums
		The technique, which relies on terahertz radiation, could be an effective and non-invasive alternative to the conventional medical imaging techniques used to diagnose these types of tumours (E Pickwell et al.
		Since cancerous tissue tends to have a higher water content than healthy tissue, terahertz radiation could be used to differentiate between the two.
		By measuring how terahertz pulses were reflected from skin on the forearms and palms of the volunteers, Pickwell and co-workers were able to distinguish between different types of skin, such as dry and normal skin.
	www.advancedphysics.org /forum/showthread.php?t=531 (366 words)

	TeraView
		The ‘terahertz gap’ – where until recently bright sources of light and sensitive means of detection did not exist – encompasses frequencies invisible to the naked eye in the electromagnetic spectrum, lying between microwave and infrared.
		Terahertz technology also produces faster results than X-ray and in the pharma industry enables non-destructive, internal, chemical analysis of tablets, capsules and other dosage forms.
		Moreover, the non-ionizing properties of Terahertz radiation and the relatively low power levels used indicate that it is safe.
	www.teraview.co.uk /terahertz.asp (243 words)

	Free Electron Laser Group - Research (Site not responding. Last check: 2007-10-12)
		This research explores relativistic electron beams modulated at terahertz frequencies using laser driven photoemission and covers three distinct areas: laser beam modulation; electron beam dynamics; and an application of electron beam modulation, the generation of terahertz radiation.
		One application of the deliberate modulation of an electron beam is the generation of coherent radiation, as seen in many devices ranging from the klystron to the free electron laser.
		Transition radiation measured by a bolometric detector is compared to expected results based on the longitudinal electron beam distributions predicted by PARMELA simulations as well as measurements from the accelerator system.
	www.ireap.umd.edu /FEL/Research/Radiation.htm (456 words)

	Technology \| Terahertz rays beam past hype
		Terahertz frequencies lie between microwaves at the low end, and the infrared end of the visible spectrum at the top end.
		Seven years ago, "terahertz rays" were touted as a replacement for dental x-rays, but they have yet to make it into your dentist's surgery.
		Terahertz radiation penetrates the covering, hits the unknown substance and bounces back, subtly changed.
	technology.guardian.co.uk /Print/0,,329476835-117422,.html (845 words)

	Blinded By The Light At 20,000 THz
		The name "terahertz radiation" derives from the frequency of the radiation -- of the order of one trillion oscillations per second.
		Terahertz radiation is thus located in the spectrum of electromagnetic radiation between the upper end of the microwave range (mm wavelength) and the far infrared (hundredths of mm).
		Sending any energetic electron beam through a magnetic field makes the beam emit radiation, so-called synchrotron radiation, a process that is greatly enhanced (coherent synchrotron radiation) when the length of the electron bunches is as short or shorter than the radiation wavelength of interest.
	www.spacedaily.com /news/laser-03b.html (918 words)

	LiveScience.com - Shadowy T-rays: Hunting Tumors and Exploring the Universe
		Between microwaves and X-rays, in the least explored region of the spectrum, lie T-rays, or terahertz radiation, the most common form of radiation in the universe.
		With more efficient sources and detectors of terahertz radiation, researchers in the last decade have begun to develop waveguides, filters, and beam splitters to manipulate T-rays.
		The Herschel Space Observatory, a satellite due to launch in 2008 is the terahertz version of the Hubble telescope.
	www.livescience.com /technology/060728_t-rays.html (740 words)

	Airports test terahertz imaging - optics.org
		This means that a terahertz imaging system can potentially reveal the presence of concealed objects such as knives and guns and also smuggled items such as narcotics, alcohol and money.
		He says that the big advantage of their detector technology is that it is passive, meaning that no illumination source of terahertz waves is required.
		A Cambridge-based start-up Teraview is also developing active terahertz spectroscopy systems for the use in pharmaceuticals industry and medical fields.
	optics.org /articles/news/11/7/15/1/terahertz (435 words)

	Terahertz Source Employs Intracavity Optical Parametric Oscillator
		Terahertz radiation â” electromagnetic waves in the spectral region between the far-infrared and microwaves â” has applications from medical imaging and the detection of illicit drugs to security screening.
		Terahertz radiation is useful for a variety of applications, including the detection of illicit drugs, because it is transmitted through many materials that are opaque to optical and radio wavelengths (top).
		Using the source, the scientists generated 5 nJ of terahertz radiation in a pulse less than 8 ns in length.
	www.photonics.com /content/spectra/2006/May/spectroscopy/82573.aspx (641 words)

	NJIT physicist sees terahertz imaging as ultimate defense against terrorism
		Since 1995, Terahertz imaging has grown in importance as new and sophisticated devices and equipment have empowered scientists to understand its potential.
		When a Terahertz system is used correctly, people can see through concealing barriers such as packaging, corrugated cardboard, walls, clothing, shoes, book bags, pill coatings, etc. in order to probe for concealed or falsified materials.
		Terahertz radiation also poses minimal or no health risk to either the person being scanned or the THz system operator.
	www.eurekalert.org /pub_releases/2005-10/njio-nps103105.php (621 words)

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