Terahertz timedomain spectroscopy for noninvasive assessment of. Jan 24, 2014 terahertz thz imaging provides cutting edge technique in biology, medical sciences and nondestructive evaluation. Some of the terahertz radiation is reflected from the article and the remainder of the terahertz radiation is transmitted through the article. A terahertz spectrometer having a wider range of terahertz radiation source, high temporal resolution of scanning us 20070235658 a1 us20070235658 a1 us 20070235658a1 us 824605 a us824605 a us 824605a us 2007235658 a1 us2007235658 a1 us 2007235658a1 authority us united states prior art keywords terahertz system radiation article voxels prior art date 20040526 legal status the. Thz radiation is therefore useful for imaging applications, which also will be briefly. Terahertz timedomain spectroscopy and standoff spectral imaging for detection. Terahertz timedomain spectroscopy, thztds, is a spectroscopic technique for determining the properties of a sample probed by short pulses of terahertz radiation. Walters contributions to the terahertz lab include the development of three types of phantoms. Ultranarrowband volume holographic grating vhgbased notch filters can extend the range of raman spectroscopy into the terahertz regime using a singlestage spectrometer, yielding important data on molecular structure for a wide variety of materials. Terahertz imaging with subwavelength resolution by. Therefore, thz spectroscopy provides a particularly. Us20090206263a1 terahertz time domain and frequency.
This book presents the current state of knowledge in the field of terahertz spectroscopy, providing a comprehensive source of information for beginners and experienced researchers alike whose interests lie in this area. Terahertz frequency continuouswave spectroscopy and imaging. Thz radiation sits between the infrared and microwave regions of the electromagnetic spectrum, but unlike uvvis or ir spectroscopy, there are currently no competitive straight. Terahertz for weapon and explosive detection megan r. Us20070235658a1 terahertz imaging system for examining. Teraview is the worlds first and leading company focused upon terahertz light. Specialising in spectroscopy, semiconductor and coatings imaging systems. The goal of the terahertz project is to develop new tools for imaging and analyzing biological systems with the help of terahertz 1012 hz radiation. We describe terahertz timedomain spectroscopy and examine the terahertz. For example, a system designed to screen passengers in an airport for hidden weapons and explosives would focus on maximizing the contrast between threat materials and the human body with high resolution, but without placing too much emphasis on.
The future thz imaging system will apply innovative pattern recognition and classification methods to distinguish explosives from nonexplosive objects via these thz spectra. However, due to the long wavelength of the thz wave, the obtained resolution of. The advent of thzfrequency imaging using a timedomain system has. The computational techniques employed in terahertz and lowfrequency raman spectroscopy are used to calculate the vibrational modes of a solid and have grown out of a branch of computational chemistry that stems from the initial release of gaussian in the 1970s. Terahertzbased imaging in medical diagnostics terasense. Terahertz pulsed imaging of skin cancer in the time and. Some data processing methods have been adopted to reconstruct the thz image. Terahertz thz imaging provides cutting edge technique in biology, medical sciences and nondestructive evaluation. Accessing molecular structure with raman spectroscopy. Menlo systems novel teraasops highspeed thz timedomain spectrometer system uses this technique to temporally scan thz pulse traces at a revolutionary high rate. The first images generated using terahertz radiation date from the 1960s. Absorption spectra of several explosives tnt trinitrotoluene or trotyl. Terahertz thz imaging which is a new technology for material classification and nondestructive detection has been extensively investigated in the pa.
Terahertz spectroscopy detects and controls properties of matter with electromagnetic fields that are in the frequency range between a few hundred gigahertz and several terahertz abbreviated as thz. In this case the gouy phase shift modifies the retrieved dielectric spectra of thick samples opt. By obtaining both frequency and time domain information, terahertz imaging can ensure enhanced detection of cancer and other inflammation areas, and provide sharper imaging and molecular fingerprinting. Recent developments of the terahertz electromagnetic wave technology now offer interesting applications in biological imaging.
Terahertz radiation sources for imaging and sensing. Measurements of semiconductors, ferroelectric crystals of current industrial interest, photonic crystals and biomolecules by means of standard thztds are shown first, then modified versions such as attenuated total reflection spectroscopy and. Terahertz time domain spectroscopy thztds is one of the most successful fields of thz optoelectronics. Angledependent terahertz timedomain spectroscopy of amino acid single. Dec 01, 2010 moreover, the absorption spectra of melamine and glucose are obtained by using a standard thz time domain spectroscopy system tds for comparison. Detection and identification of concealed rdx using terahertz. Terahertz timedomain spectroscopy for distinguishing. Terahertz imaging and spectroscopy archive ouverte hal. When the size of dielectric grain boundaries are comparable to the thz wavelengths, spectral features can be obscured due to electromagnetic.
Elshenawee, timedomain terahertz imaging and spectroscopy of xray blocking and scattering coatings, proc. Time domain spectroscopy and imaging using terakit from rainbow photonics using thz radiation. The developed experimental terahertz timedomain spectroscopy system. Osa terahertz timedomain spectroscopy and imaging of. Planken and his colleagues have also developed a new method to overcome the diffraction limit in terahertz imaging and have improved the resolution of terahertz imaging by a factor of almost. We find a significant difference in the absorption between the two types of rna strands, and we show that we can use this difference to record images of spot. The core of the system is based on terahertz time domain spectroscopy. The refractive index and absorption coefficient characteristics of these phantoms were studied using timedomain terahertz spectroscopy performed on the pulsed terahertz system at the university of arkansas. Thz timedomain spectroscopy terahertz spectroscopy is a tool for collecting spectral measurements in the far infrared approximately 3 100 wavenumbers. Terahertz thz imaging which is a new technology for material classification and nondestructive detection has been extensively investigated in the past decade. Terahertz timedomain spectroscopy thztds is a leading method for spectroscopy, imaging and nondestructive testing 1,2 in the frequency range of 0.
Application description thz timedomain spectroscopy is used to characterize material properties by measuring the complex frequency response within the frequency range from 0. It is based on organic crystals to allow access to terahertz frequencies up to 20 thz not available with conventional antennas. Temperaturedependent farinfrared spectra of single crystals of. Menlo systems novel teraasops highspeed thz time domain spectrometer system uses this technique to temporally scan thz pulse traces at a revolutionary high rate. We describe the application of a new highbrightness, terahertzbeam system to timedomain spectroscopy. However, from the timedomain terahertz map alone, we cannot tell if a speci. Terahertz spectroscopy and imaging laboratory for optics. The key features are a broad spectral bandwidth of about 3 thz due to the ultra short thz pulses consisting of only a few cycles of the. We currently measure a full 35pslong terahertz electric field with a dynamic range of more than 5000 in a total measurement time of 20 ms, he said. Data collection in this frequency range has many advantages. We will focus on three forms of terahertz spectroscopy. Imaging and analysis of heterogeneous breast cancer tissue using pulsed terahertz system. Usingtime domain analysis the contrast betweendiseased and normal tissue has been shownto be statistically significant, andregions of. Terahertz timedomain and lowfrequency raman spectroscopy of.
Terahertz timedomain spectroscopy for explosive imaging. The second chapter presents terahertz timedomain spectroscopy and spectral imaging. A system to detect an article includes one or more terahertz modules. Quantitative analysis of component mixtures is an important application of terahertz timedomain spectroscopy thztds and has attracted broad interest in recent research. Chemometrics applied to terahertz explosive images. Anwar, terahertz characterization of electronic components and. Terahertz time domain spectroscopy thz spectroscopy is a growing area of research due to its applications in many areas of science, security and product testing. Thz radiation is attractive for many applications due to its ability to penetrate through a wide range of dielectric materials including clothing, paper. Following the development of laser based terahertz timedomain spectroscopy in the 1980s and 1990s the field of thz science and technology expanded rapidly, to. Terahertz frequency continuouswave spectroscopy and.
We use terahertz timedomain spectroscopy thztds to measure the farinfrared dielectric function of two artificial rna single strands, composed of polyadenylic acid polya and polycytidylic acid polyc. Measurements of semiconductors, ferroelectric crystals of current industrial interest, photonic crystals and biomolecules by means of standard thztds are shown first, then modified versions such as attenuated total reflection spectroscopy and ellipsometry are described. A terahertz spectrometer having a wider range of terahertz radiation source, high temporal resolution of scanning feb 29, 2012 imaging stationtm motion controller custom gantry tscannertm tray computed tomography spectroscopy station tm tray explorer software tray 4000 control unit 100 hz and 1khz tray tgaugetm tray transmitter and receiver tray 4000 base system g d new for 2010. Some frequencies of terahertz radiation can be used for 3d imaging of teeth and may be more accurate than conventional xray imaging in dentistry. Thz timedomain spectroscopy the schmuttenmaer research. The generation and detection of terahertz waves has been a difficult challenge until recently new techniques such as terahertz time domain spectroscopy have become commercially available.
Terahertz spectroscopy and imaging modern techniques and. Terahertz thz imaging is a widely used technique in the study and detection of many chemicals and biomolecules in polycrystalline form because the spectral absorption signatures of these target materials often lie in the thz frequencies. Processing this waveform will present the characters of the object. A userfriendly software program comprising a graphical user interface gui has been developed by the author for automation of implementation of the proposed system. Uk basic technology program, the european commission program teranova. This process can be fully implemented on thz time domain spectroscopy tds systems, and partially on continuouswave thz imaging systems. In order to create thz pulses, a diodepumped cw laser at 532 nm pumps a modelocked ti. By analyzing the propagation of terahertz electromagnetic pulses through water vapor, we have made what we believe are the most accurate measurements to date of the absorption cross sections of the water molecule for the nine strongest lines in the frequency. Mitigating the effects of granular scattering using.
This process can be fully implemented on thz timedomain spectroscopy tds systems, and partially on continuouswave thz imaging systems. Many molecules, especially biomolecules, provide fingerprint spectroscopic lines in the terahertz region. Us20090206263a1 terahertz time domain and frequency domain. Terahertz thz technology has been demonstrated as a promising tool for detection of explosives and is being developed for aviation screening and sensing of improvised explosive devices. Terahertz timegated spectral imaging for content extraction. In the programs, the user is asked to upload the waveforms of the. Terahertz time domain spectroscopy and imaging with terakit. In this regime it is possible to observe various fundamental resonances, such as electronic and phononic excitations in solidstate materials. Terahertz time domain spectroscopy and imaging with. It is based on organic crystals allowing a spectral range from 0. Thz timedomain spectroscopy the schmuttenmaer research group. Terahertz applications for detection of explosives drs. By measuring in the timedomain, the technique can provide more information than conventional fouriertransform spectroscopy, which is only sensitive to the amplitude. As examples of identification, we used the thz signals reflected from the plastic explosive pwm c4 with both rough and concave surface.
Since hu and nuss reported their first image achieved by using the terahertz thz timedomain spectroscopy tds in 1995, this technology has been considered as one of the most promising applications of the thz wave science and technology. The timedomain waveform acquired at each point of the object by using the thz timedomain spectroscopy contains much information about the object. Thz imaging and sensing for security applicationsexplosives. Over the past three decades a new spectroscopic technique with unique possibilities has emerged.
In 1995, binbin hu and martin nuss at bell labs created a terahertz imaging system using time domain spectroscopy, and they coined the term tray for these short, broadband terahertz pulses. In manybody systems, several of the relevant states have an energy difference that matches with the energy of a thz photon. This terahertz system offers the most flexible solution for terahertz spectroscopy and terahertz imaging. A terahertz imaging system was built from commercially available hardware whose functionality was integrated through homemade software with the goal of building a terahertz imaging platform for which other terahertz technologies would be born out of. Overthe last two years this technique has beenapplied to the study of in vitrobasal cell carcinoma bcc. When the size of dielectric grain boundaries are comparable to the thz wavelengths, spectral features can be obscured due to electromagnetic scattering. A method and system for enhancing the resolution of terahertz. Terahertz reflection spectroscopy for the detection of. By analyzing the propagation of terahertz electromagnetic pulses through water vapor, we have made what we believe are the most accurate measurements to date of the absorption cross sections of the water molecule for the nine strongest lines in the frequency range from 0. We describe the application of a new highbrightness, terahertz beam system to time domain spectroscopy.
The design of imaging systems will certainly be driven by the performance requirements of specific applications. The book aims to explain the fundamental physics that underpins terahertz technology and to describe its key applications. For the purpose of detecting and identifying explosives, we. Pdf standoff detection of hidden explosives and cold and fire. Leahyhoppa jhu, applied physics laboratory, laurel, md 20723, usa abstract terahertz thz technology has experienced large growth within the past 20 years. Abstract we use terahertz timedomain spectroscopy thztds to measure the farinfrared dielectric function of two artificial rna single strands, composed of polyadenylic acid polya and polycytidylic acid polyc. We use terahertz time domain spectroscopy thztds to measure the farinfrared dielectric function of two artificial rna single strands, composed of polyadenylic acid polya and polycytidylic acid polyc.
Absorption spectra of two chemicals on corresponding pixels of thz real time images obtained by the two detection techniques and the results measured by tds are shown in fig. For the thz imaging technology, there are three important factors. The method can detect structural defects in foams, wooden objects5, plastic components6, composites7, pharmaceutical products coatings8 and cultural artefacts911. Terahertz realtime imaging with balanced electrooptic detection. University of connecticut comparison of thz imaging with xray kiarash ahi, navid asadizanjani, sina shahbazmohamadi, mark tehranipoor and mehdi anwar if you want to use these slides, please reference to our work. We find a significant difference in the absorption between the two types of rna strands, and we show that we can use this difference to record images of spot arrays of the rna strands. In physics, terahertz timedomain spectroscopy is a spectroscopic technique in which the properties of matter are probed with short pulses of terahertz radiation. Terahertz pulsed imaging tpi is a new medical imaging modality forthe detection of epithelial cancers.
In this project, we first used thz time domain spectroscopy thztds to investigate explosives and establish a spectra database of these materials in the thz frequency range. In physics, terahertz time domain spectroscopy thztds is a spectroscopic technique in which the properties of matter are probed with short pulses of terahertz radiation. A method and system for enhancing the resolution of. Identification of high explosive rdx using terahertz imaging and spectral. It can be used with any femtosecond laser at telecom wavelengths. Terahertz spectrometers the rigel 1550 terahertz fiber coupled spectrometer is an innovative and reliable turnkey system with a built. Terahertz spectroscopy is a rapidly evolving field with interesting applications in medical imaging, security, scientific imaging chemistry, biochemistry, astronomy, communications, and manufacturing. Continuouswave terahertz radiation imaging of explosives imaging and explosives identification can be achieved simultaneously by performing raster scans of an object at multiple thz frequencies. The future thz imaging system will apply innovative pattern recognition and classification methods to distinguish explosives from non explosive objects via these thz spectra. The journal of physical chemistry a oa policy acs open access programs. Jul 23, 2012 time domain spectroscopy and imaging using terakit from rainbow photonics using thz radiation. Although the accuracy of quantitative analysis using thztds is affected by a host of factors, wavelength selection from the samples thz absorption spectrum is the most. Osa terahertz timedomain spectroscopy of water vapor. Advances in technology have enabled a variety of applications of thz spectroscopy and imaging within the civilian and military arenas.
Terahertz timedomain spectroscopy experiments are usually carried out with focused beams. Terahertz spectroscopy of explosives and drugs sciencedirect. The terahertz domain lies between the microwave and the far infrared domains. The generation and detection scheme is sensitive to the samples effect on both the amplitude and the phase of the terahertz radiation. These simulations are often carried out using commercial software such as. High effective timedependent thz spectroscopy method for the. Diffractionlimited imaging with terahertz radiation over the last 10 years, the majority of research developments in terahertz imaging have made use of terahertz timedomain spectroscopy, in which the terahertz radiation is generated in the form of singlecycle pulses of duration 1ps or less see. Terahertz timedomain spectroscopy thztds is one of the most successful fields of thz optoelectronics. Terahertz imaging finds new applications vision systems. The image contrast at specific frequencies could help the identify whether a substance within a package is an explosive. Each module either generates or receives, or both generates and receives, terahertz radiation.
Terahertz timedomain spectroscopy thz tds is a leading method for spectroscopy, imaging and nondestructive testing 1,2 in the frequency range of 0. Following the development of laser based terahertz time domain spectroscopy in the 1980s and 1990s the field of thz science and technology expanded rapidly, to the extent that it now touches many. Also, it shows the visualized direct result and the way the software recognizes. Terahertz timedomain spectroscopy of solid samples. At the same time, it extends the detection window to nanoseconds, pushing the spectral resolution into the region of hundreds of mhz. Mitigating the effects of granular scattering using cepstrum.
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