Sample records for terahertz imaging system

  1. Terahertz Imaging Systems With Aperture Synthesis Techniques

    DEFF Research Database (Denmark)

    Krozer, Viktor; Löffler, Torsten; Dall, Jørgen


    in this paper. An active system operation allows for a wide dynamic range, which is important for image quality. The described instruments employ a multichannel high-sensitivity heterodyne architecture and aperture filling techniques, with close to real-time image acquisition time. In the case of the photonic...... imaging system, mechanical scanning is completely obsolete. We show 2-D images of simulated 3-D image data for both systems. The reconstruction algorithms are suitable for 3-D real-time operation, only limited by mechanical scanning....

  2. Point Spread Function Estimation for a Terahertz Imaging System

    Directory of Open Access Journals (Sweden)

    Popescu DanC


    Full Text Available We present a method for estimating the point spread function of a terahertz imaging system designed to operate in reflection mode. The method is based on imaging phantoms with known geometry, which have patterns with sharp edges at all orientations. The point spread functions are obtained by a deconvolution technique in the Fourier domain. We validate our results by using the estimated point spread functions to deblur several images of natural scenes and by direct comparison with a point source response. The estimations turn out to be robust and produce consistent deblurring quality over the entire depth of the focal region of the imaging system.

  3. Non-invasive detection of murals with pulsed terahertz reflected imaging system (United States)

    Yuan, Minjie; Sun, Wenfeng; Wang, Xinke; Ye, Jiasheng; Wang, Sen; Zhang, Qunxi; Zhang, Yan


    Pulsed terahertz reflected imaging technology has been expected to have great potential for the non-invasive analysis of artworks. In this paper, three types of defects hidden in the plaster used to simulate the cases of defects in the murals, have been investigated by a pulsed terahertz reflected imaging system. These preset defects include a circular groove, a cross-shaped slit and a piece of "Y-type" metal plate built in the plaster. With the terahertz reflective tomography, information about defects has been determined involving the thickness from the surface of sample to the built-in defect, the profile and distribution of the defect. Additionally, three-dimensional analyses have been performed in order to reveal the internal structure of defects. Terahertz reflective imaging can be applied to the defect investigation of the murals.

  4. A Practical and Portable Solids-State Electronic Terahertz Imaging System

    Directory of Open Access Journals (Sweden)

    Ken Smart


    Full Text Available A practical compact solid-state terahertz imaging system is presented. Various beam guiding architectures were explored and hardware performance assessed to improve its compactness, robustness, multi-functionality and simplicity of operation. The system performance in terms of image resolution, signal-to-noise ratio, the electronic signal modulation versus optical chopper, is evaluated and discussed. The system can be conveniently switched between transmission and reflection mode according to the application. A range of imaging application scenarios was explored and images of high visual quality were obtained in both transmission and reflection mode.

  5. Terahertz Tools Advance Imaging for Security, Industry (United States)


    Picometrix, a wholly owned subsidiary of Advanced Photonix Inc. (API), of Ann Arbor, Michigan, invented the world s first commercial terahertz system. The company improved the portability and capabilities of their systems through Small Business Innovation Research (SBIR) agreements with Langley Research Center to provide terahertz imaging capabilities for inspecting the space shuttle external tanks and orbiters. Now API s systems make use of the unique imaging capacity of terahertz radiation on manufacturing floors, for thickness measurements of coatings, pharmaceutical tablet production, and even art conservation.

  6. Terahertz imaging for styrofoam inspection (United States)

    Pradarutti, B.; Riehemann, S.; Notni, G.; Tünnermann, A.


    Imaging of styrofoam with the help of ultrashort Terahertz pulses is investigated. With a combination of pulse amplitude and time delay imaging it is possible to speed up the measurement about two orders of magnitudes.

  7. Power-scalable, polarization-stable, dual-colour DFB fibre laser system for CW terahertz imaging

    DEFF Research Database (Denmark)

    Eichhorn, Finn; Pedersen, Jens Engholm; Jepsen, Peter Uhd

    Imaging with electromagnetic radiation in the terahertz (THz) range has received a large amount of attention during recent years. THz imaging systems have diverse potential application areas such as security screening, medical diagnostics and non-destructive testing. We will discuss a power...

  8. Terahertz Imaging for Biomedical Applications Pattern Recognition and Tomographic Reconstruction

    CERN Document Server

    Yin, Xiaoxia; Abbott, Derek


    Terahertz Imaging for Biomedical Applications: Pattern Recognition and Tomographic Reconstruction presents the necessary algorithms needed to assist screening, diagnosis, and treatment, and these algorithms will play a critical role in the accurate detection of abnormalities present in biomedical imaging. Terahertz biomedical imaging has become an area of interest due to its ability to simultaneously acquire both image and spectral information. Terahertz imaging systems are being commercialized with an increasing number of trials performed in a biomedical setting. Terahertz tomographic imaging and detection technology contributes to the ability to identify opaque objects with clear boundaries,and would be useful to both in vivo and ex vivo environments. This book also: Introduces terahertz radiation techniques and provides a number of topical examples of signal and image processing, as well as machine learning Presents the most recent developments in an emerging field, terahertz radiation Utilizes new methods...

  9. Terahertz polarization imaging

    NARCIS (Netherlands)

    Van der Valk, N.C.J.; Van der Marel, W.A.M.; Planken, P.C.M.


    We present a new method to measure the polarization state of a terahertz pulse by using a modified electrooptic sampling setup. To illustrate the power of this method, we show two examples in which the knowledge of the polarization of the terahertz pulse is essential for interpreting the results:

  10. Terahertz Spectroscopy and Imaging

    CERN Document Server

    Zeitler, Axel; Kuwata-Gonokami, Makoto


    "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. The book aims to explain the fundamental physics that underpins terahertz  technology and to describe its key applications. Highlights of scientific research in the field of terahertz science are also outlined in some chapters, providing an overview as well as giving an insight into future directions for research.  Over the past decade terahertz spectroscopy has developed into one of the most rapidly growing areas of its kind, gaining an important impact across a wide range of scientific disciplines. Due to substantial advances in femtosecond laser technology, terahertz time-domain spectroscopy (THz-TDS) has established itself as the dominant spectroscopic technique for experimental scientists interested in measurements at this frequency range. In solids and liquids THz radiation is in reso...

  11. Continuous-wave terahertz imaging of nonmelanoma skin cancers (United States)

    Joseph, Cecil Sudhir

    Continuous wave terahertz imaging has the potential to offer a safe, non-invasive medical imaging modality for detecting different types of human skin cancers. Terahertz pulse imaging (TPI) has already shown that there is contrast between basal cell carcinoma and normal skin. Continuous-wave imaging offers a simpler, lower cost alternative to terahertz pulse imaging. This project aims to isolate the optimal contrast frequency for a continuous wave terahertz imaging system and demonstrate transmission based, in-vitro , imaging of thin sections of non-melanoma skin cancers and correlate the images to sample histology. The aim of this project is to conduct a proof-of-principle experiment that establishes whether continuous-wave terahertz imaging can detect differences between cancerous and normal tissue while outlining the basic requirements for building a system capable of performing in vivo tests.

  12. Terahertz Imaging of Subjects With Concealed Weapons

    National Research Council Canada - National Science Library

    Dickinson, Jason C; Goyette, Thoms M; Gatesman, Andrew J; Joseph, Cecil S; Root, Zachary G; Giles, Robert H; Waldman, Jerry; Nixon, William E


    .... Two contrasting techniques were used to collect the imagery. Both methods made use of in-house transceivers, consisting of two ultra-stable far-infrared lasers, terahertz heterodyne detection systems, and terahertz anechoic chambers...

  13. Terahertz (THZ) Imaging (United States)


    Especially for thin films of material the absorption and time delay of a THz pulse are mostly too low to be detected. 48. Nemec, H.; Kuzel, P.; Khazan, M...the summary) states that the use of thin ZnTe electro-optic sensors for coherent characterization of a freely propagating terahertz beam...on a GaAs wafer is determined by the diameter of the gating- 40 beam-induced thin photo carrier layer. With a dynamic aperture created on a GaAs

  14. Enhancement of spatial resolution of terahertz imaging systems based on terajet generation by dielectric cube

    Directory of Open Access Journals (Sweden)

    Hai Huy Nguyen Pham


    Full Text Available The terahertz (THz, 0.1–10 THz region has been attracting tremendous research interest owing to its potential in practical applications such as biomedical, material inspection, and nondestructive imaging. Those applications require enhancing the spatial resolution at a specific frequency of interest. A variety of resolution-enhancement techniques have been proposed, such as near-field scanning probes, surface plasmons, and aspheric lenses. Here, we demonstrate for the first time that a mesoscale dielectric cube can be exploited as a novel resolution enhancer by simply placing it at the focused imaging point of a continuous wave THz imaging system. The operating principle of this enhancer is based on the generation—by the dielectric cuboid—of the so-called terajet, a photonic jet in the THz region. A subwavelength hotspot is obtained by placing a Teflon cube, with a 1.46 refractive index, at the imaging point of the imaging system, regardless of the numerical aperture (NA. The generated terajet at 125 GHz is experimentally characterized, using our unique THz-wave visualization system. The full width at half maximum (FWHM of the hotspot obtained by placing the enhancer at the focal point of a mirror with a measured NA of 0.55 is approximately 0.55λ, which is even better than the FWHM obtained by a conventional focusing device with the ideal maximum numerical aperture (NA = 1 in air. Nondestructive subwavelength-resolution imaging demonstrations of a Suica integrated circuit card, which is used as a common fare card for trains in Japan, and an aluminum plate with 0.63λ trenches are presented. The amplitude and phase images obtained with the enhancer at 125 GHz can clearly resolve both the air-trenches on the aluminum plate and the card’s inner electronic circuitry, whereas the images obtained without the enhancer are blurred because of insufficient resolution. An increase of the image contrast by a factor of 4.4 was also obtained using

  15. Convergence of Terahertz Sciences in Biomedical Systems

    CERN Document Server

    Kim, Yong; Han, Haewook; Han, Joon; Ahn, Jaewook; Son, Joo-Hiuk; Park, Woong-Yang; Jeong, Young


    Recent technological breakthrough in the field of Terahertz radiation has triggered new applications in biology and biomedicine. Particularly, biological applications are based on the specific spectroscopic fingerprints of biological matter in this spectral region. Historically with the discovery of new electromagnetic wave spectrum, we have always discovered new medical diagnostic imaging systems. The use of terahertz wave was not realized due to the absence of useful terahertz sources. Now after successful generation of THz waves, it is reported that a great potential for THz wave exists for its resonance with bio-molecules. There are many challenging issues such as development of THz passive and active instrumentations, understanding of THz-Bio interaction for THz spectroscopy, THz-Bio nonlinear phenomena and safety guideline, and THz imaging systems. Eventually the deeper understanding of THz-Bio interaction and novel THz systems enable us to develop powerful THz biomedical imaging systems which can contr...

  16. Terahertz in-line digital holographic multiplane imaging method (United States)

    Huang, Haochong; Wang, Dayong; Rong, Lu; Li, Weihua; Wang, Yunxin


    Terahertz waves of which frequency spans from 0.1 to 10 THz bridge the gap between the infrared spectrum and microwaves. Owing to the special features of terahertz wave, such as penetrability and non-ionizing, terahertz imaging technique is a very significant and important method for inspections and detections. Digital holography can reconstruct the amplitude and phase distributions of a sample without scanning and it already has many successful applications in the area of visible and infrared light. The terahertz in-line digital holographic multi-plane imaging system which is presented in this paper is the combination of a continuous-wave terahertz source and the in-line scheme of digital holography. In order to observe a three dimensional (3D) shape sample only a portion of which appears in good focus, the autofocusing algorithm is brought to the data process. The synthetic aperture method is also applied to provide the high resolution imaging effect in the terahertz waveband. Both intrinsic twin images and defocused objective images confuse the quality of the image in an individual reconstructed plane. In order to solve this issue, phase retrieval iteration algorithm is used for the reconstruction. In addition, the reconstructed amplitude image in each plane multiplies the mask of which the threshold depends on the values of the autofocusing curve. A sample with simple artificial structure is observed which verifies that the present method is an authentic tool to acquire the multi-plane information of a target in terahertz waves. It can expect a wide application in terahertz defect detecting, terahertz medical inspection and other important areas in the future.

  17. Brain tumor imaging of rat fresh tissue using terahertz spectroscopy (United States)

    Yamaguchi, Sayuri; Fukushi, Yasuko; Kubota, Oichi; Itsuji, Takeaki; Ouchi, Toshihiko; Yamamoto, Seiji


    Tumor imaging by terahertz spectroscopy of fresh tissue without dye is demonstrated using samples from a rat glioma model. The complex refractive index spectrum obtained by a reflection terahertz time-domain spectroscopy system can discriminate between normal and tumor tissues. Both the refractive index and absorption coefficient of tumor tissues are higher than those of normal tissues and can be attributed to the higher cell density and water content of the tumor region. The results of this study indicate that terahertz technology is useful for detecting brain tumor tissue.

  18. Terahertz imaging devices and systems, and related methods, for detection of materials (United States)

    Kotter, Dale K.


    Terahertz imaging devices may comprise a focal plane array including a substrate and a plurality of resonance elements. The plurality of resonance elements may comprise a conductive material coupled to the substrate. Each resonance element of the plurality of resonance elements may be configured to resonate and produce an output signal responsive to incident radiation having a frequency between about a 0.1 THz and 4 THz range. A method of detecting a hazardous material may comprise receiving incident radiation by a focal plane array having a plurality of discrete pixels including a resonance element configured to absorb the incident radiation at a resonant frequency in the THz, generating an output signal from each of the discrete pixels, and determining a presence of a hazardous material by interpreting spectral information from the output signal.

  19. Terahertz Imaging of Three-Dimensional Dehydrated Breast Cancer Tumors (United States)

    Bowman, Tyler; Wu, Yuhao; Gauch, John; Campbell, Lucas K.; El-Shenawee, Magda


    This work presents the application of terahertz imaging to three-dimensional formalin-fixed, paraffin-embedded human breast cancer tumors. The results demonstrate the capability of terahertz for in-depth scanning to produce cross section images without the need to slice the tumor. Samples of tumors excised from women diagnosed with infiltrating ductal carcinoma and lobular carcinoma are investigated using a pulsed terahertz time domain imaging system. A time of flight estimation is used to obtain vertical and horizontal cross section images of tumor tissues embedded in paraffin block. Strong agreement is shown comparing the terahertz images obtained by electronically scanning the tumor in-depth in comparison with histopathology images. The detection of cancer tissue inside the block is found to be accurate to depths over 1 mm. Image processing techniques are applied to provide improved contrast and automation of the obtained terahertz images. In particular, unsharp masking and edge detection methods are found to be most effective for three-dimensional block imaging.

  20. Terahertz polarization imaging for colon cancer detection (United States)

    Doradla, Pallavi; Alavi, Karim; Joseph, Cecil S.; Giles, Robert H.


    Continuous wave terahertz (THz) imaging has the potential to offer a safe, noninvasive medical imaging modality for delineating colorectal cancer. The terahertz reflectance measurements of fresh 3 - 5 mm thick human colonic excisions were acquired using a continuous-wave polarization imaging technique. A CO2 optically pumped Far- Infrared molecular gas laser operating at 584 GHz was used to illuminate the colon tissue, while the reflected signals were detected using a liquid Helium cooled silicon bolometer. Both co-polarized and cross-polarized remittance from the samples was collected using wire grid polarizers in the experiment. The experimental analysis of 2D images obtained from THz reflection polarization imaging techniques showed intrinsic contrast between cancerous and normal regions based on increased reflection from the tumor. Also, the study demonstrates that the cross-polarized terahertz images not only correlates better with the histology, but also provide consistent relative reflectance difference values between normal and cancerous regions for all the measured specimens.

  1. Terahertz pulsed imaging study of dental caries (United States)

    Karagoz, Burcu; Altan, Hakan; Kamburoglu, Kıvanç


    Current diagnostic techniques in dentistry rely predominantly on X-rays to monitor dental caries. Terahertz Pulsed Imaging (TPI) has great potential for medical applications since it is a nondestructive imaging method. It does not cause any ionization hazard on biological samples due to low energy of THz radiation. Even though it is strongly absorbed by water which exhibits very unique chemical and physical properties that contribute to strong interaction with THz radiation, teeth can still be investigated in three dimensions. Recent investigations suggest that this method can be used in the early identification of dental diseases and imperfections in the tooth structure without the hazards of using techniques which rely on x-rays. We constructed a continuous wave (CW) and time-domain reflection mode raster scan THz imaging system that enables us to investigate various teeth samples in two or three dimensions. The samples comprised of either slices of individual tooth samples or rows of teeth embedded in wax, and the imaging was done by scanning the sample across the focus of the THz beam. 2D images were generated by acquiring the intensity of the THz radiation at each pixel, while 3D images were generated by collecting the amplitude of the reflected signal at each pixel. After analyzing the measurements in both the spatial and frequency domains, the results suggest that the THz pulse is sensitive to variations in the structure of the samples that suggest that this method can be useful in detecting the presence of caries.

  2. Investigation of Layer Structure of the Takamatsuzuka Mural Paintings by Terahertz Imaging Technique (United States)

    Inuzuka, M.; Kouzuma, Y.; Sugioka, N.; Fukunaga, K.; Tateishi, T.


    Terahertz imaging can be a powerful tool in conservation science for cultural heritages. In this study, a new terahertz imaging system was applied to the Takamatsuzuka mural painting of a blue dragon, and the condition of the plaster layer was diagnosed. As a result, the locations where the plaster layer appears solid on the surface but in actuality may have peeled off the underlying tuff stone were revealed and viewed as two-dimensional images.

  3. Terahertz pulsed imaging for the monitoring of dental caries: a comparison with x-ray imaging (United States)

    Karagoz, Burcu; Kamburoglu, Kıvanc; Altan, Hakan


    Dental caries in sliced samples are investigated using terahertz pulsed imaging. Frequency domain terahertz response of these structures consistent with X-ray imaging results show the potential of this technique in the detection of early caries.

  4. Terahertz Radar Imaging Based on Time-domain Spectroscopy

    Directory of Open Access Journals (Sweden)

    Wei Ming-gui


    Full Text Available This study uses time domain terahertz radar system to discuss systematic imaging studies on the scaled models based on the improved Back-Projection (BP algorithm. We image the scaled models with different shapes and are able to distinguish spatial gaps as small as 6 mm. The Theoretical calculation predicts that the lateral resolution and the axial resolution can be as high as 0.125 mm. Center enhancement and background rings caused by the algorithm in the imaging results are also qualitatively analyzed and are proposed methods to overcome this problem.

  5. Materials for phantoms for terahertz pulsed imaging

    Energy Technology Data Exchange (ETDEWEB)

    Walker, Gillian C [Academic Unit of Medical Physics, University of Leeds, Wellcome Wing, Leeds General Infirmary, Great George Street, Leeds, LS1 3EX (United Kingdom); Berry, Elizabeth [Academic Unit of Medical Physics, University of Leeds, Wellcome Wing, Leeds General Infirmary, Great George Street, Leeds, LS1 3EX (United Kingdom); Smye, Stephen W [Department of Medical Physics and Engineering, Leeds Teaching Hospitals NHS Trust, St James University Hospital, Leeds, LS9 7TF (United Kingdom); Brettle, David S [Department of Medical Physics and Engineering, Leeds Teaching Hospitals NHS Trust, St James University Hospital, Leeds, LS9 7TF (United Kingdom)


    Phantoms are commonly used in medical imaging for quality assurance, calibration, research and teaching. They may include test patterns or simulations of organs, but in either case a tissue substitute medium is an important component of the phantom. The aim of this work was to identify materials suitable for use as tissue substitutes for the relatively new medical imaging modality terahertz pulsed imaging. Samples of different concentrations of the candidate materials TX151 and napthol green dye were prepared, and measurements made of the frequency-dependent absorption coefficient (0.5 to 1.5 THz) and refractive index (0.5 to 1.0 THz). These results were compared qualitatively with measurements made in a similar way on samples of excised human tissue (skin, adipose tissue and striated muscle). Both materials would be suitable for phantoms where the dominant mechanism to be simulated is absorption ({approx}100 cm{sup -1} at 1 THz) and where simulation of the strength of reflections from boundaries is not important; for example, test patterns for spatial resolution measurements. Only TX151 had a frequency-dependent refractive index close to that of tissue, and could therefore be used to simulate the layered structure of skin, the complexity of microvasculature or to investigate frequency-dependent interference effects that have been noted in terahertz images. (note)

  6. Biomedical Applications of Terahertz Spectroscopy and Imaging. (United States)

    Yang, Xiang; Zhao, Xiang; Yang, Ke; Liu, Yueping; Liu, Yu; Fu, Weiling; Luo, Yang


    Terahertz (THz=10(12)Hz) radiation has attracted wide attention for its unprecedented sensing ability and its noninvasive and nonionizing properties. Tremendous strides in THz instrumentation have prompted impressive breakthroughs in THz biomedical research. Here, we review the current state of THz spectroscopy and imaging in various biomedical applications ranging from biomolecules, including DNA/RNA, amino acids/peptides, proteins, and carbohydrates, to cells and tissues. We also address the potential biological effects of THz radiation during its biological applications and propose future prospects for this cutting-edge technology. Copyright © 2016 Elsevier Ltd. All rights reserved.

  7. TeraHertz imaging of hidden paint layers on canvas

    NARCIS (Netherlands)

    Adam, A.J.L.; Planken, P.C.M.; Meloni, S.; Dik, J.


    We show terahertz reflection images of hidden paint layers in a painting on canvas and compare the results with X-ray Radiography and Infrared Reflectography. Our terahertz measurements show strong reflections from both the canvas/paint interface and from the raw umber/lead white interface,

  8. Papyrus imaging with terahertz time domain spectroscopy (United States)

    Labaune, J.; Jackson, J. B.; Pagès-Camagna, S.; Duling, I. N.; Menu, M.; Mourou, G. A.


    Terahertz time domain spectroscopic imaging (THz-TDSI) is a non-ionizing, non-contact and non-destructive measurement technique that has been recently utilized to study cultural heritage artifacts. We will present this technique and the results of non-contact measurements of papyrus texts, including images of hidden papyri. Inks for modern papyrus specimens were prepared using the historical binder, Arabic gum, and two common pigments used to write ancient texts, carbon black and red ochre. The samples were scanned in reflection at normal incidence with a pulse with a spectral range between 0.1 and 1.5 THz. Temporal analysis of the signals provides the depths of the layers, and their frequency spectra give information about the inks.

  9. Terahertz Spectroscopy and Brewster Angle Reflection Imaging of Acoustic Tiles

    Directory of Open Access Journals (Sweden)

    Patrick Kilcullen


    Full Text Available A Brewster angle reflection imaging apparatus is demonstrated which is capable of detecting hidden water-filled voids in a rubber tile sample. This imaging application simulates a real-world hull inspection problem for Royal Canadian Navy Victoria-class submarines. The tile samples represent a challenging imaging application due to their large refractive index and absorption coefficient. With a rubber transmission window at approximately 80 GHz, terahertz (THz sensing methods have shown promise for probing these structures in the laboratory. Operating at Brewster’s angle allows for the typically strong front surface reflection to be minimized while also conveniently making the method insensitive to air-filled voids. Using a broadband THz time-domain waveform imaging system (THz-TDS, we demonstrate satisfactory imaging and detection of water-filled voids without complicated signal processing. Optical properties of the tile samples at low THz frequencies are also reported.

  10. Continuous-wave terahertz reflection imaging of ex vivo nonmelanoma skin cancers (United States)

    Joseph, Cecil S.; Yaroslavsky, Anna N.; Neel, Victor A.; Goyette, Thomas M.; Giles, Robert H.


    Nonmelanoma skin cancers are the most common form of cancer. Continuous wave terahertz imaging has the potential to differentiate between nonmelanoma skin cancers and normal skin. Terahertz imaging is non-ionizing and offers a high sensitivity to water content. Contrast between cancerous and normal tissue in transmission mode has already been demonstrated using a continuous wave terahertz system. The aim of this experiment was to implement a system that is capable of reflection modality imaging of nonmelanoma skin cancers. Fresh excisions of skin cancer specimens were obtained from Mohs surgeries for this study. A CO2 optically pumped far-infrared molecular gas laser was used for illuminating the tissue at 584 GHz. The reflected signal was detected using a liquid Helium cooled Silicon bolometer. The terahertz images were compared with sample histology. The terahertz reflection images exhibit some artifacts that can hamper the specificity. The beam waist at the sample plane was measured to be 0.57 mm, and the system's signal-to-noise ratio was measured to be 65 dB.

  11. High Reliability Oscillators for Terahertz Systems Project (United States)

    National Aeronautics and Space Administration — Terahertz sources based on lower frequency oscillators and amplifiers plus a chain of frequency multipliers are the workhorse technology for NASA's terahertz...

  12. Nano-Antenna For Terahertz (THz) Medical Imaging Applications Project (United States)

    National Aeronautics and Space Administration — As a result of technological breakthroughs, research and applications in the Terahertz (THz) radiation system are experiencing explosive growth. The non-ionizing...

  13. Terahertz Quantum Cascade Laser Based 3D Imaging Project (United States)

    National Aeronautics and Space Administration — LongWave Photonics proposes a terahertz quantum-cascade laser based swept-source optical coherence tomography (THz SS-OCT) system for single-sided, 3D,...

  14. Study on coding strategies for radar coded-aperture imaging in terahertz band (United States)

    Chen, Shuo; Luo, Chenggao; Deng, Bin; Qin, Yuliang; Wang, Hongqiang


    Motivated by the principle of coded-aperture imaging and microwave radar coincidence imaging (RCI), terahertz radar coded-aperture imaging (RCAI) is proposed to obtain high-resolution, forward-looking, and staring imaging. The terahertz RCAI method resolves target scatterers using the correlation processing of the modulated echoes and the reference signal matrix. This process is similar to the basic principle of RCI. To investigate the coding strategies of terahertz RCAI, this study derives three signal models describing operation with the coded aperture placed separately in the transmitting terminal and the receiving terminal and in both of them simultaneously. Furthermore, coding strategies are categorized according to coded-aperture placement and encoded signal, including amplitude modulation and phase modulation. In addition, qualitative and quantitative analysis methods are introduced to describe the resolving ability of terahertz RCAI. Numerical simulations are performed to analyze and compare the performance on different coding strategies. These analyses can provide constructive guidelines for the design of terahertz RCAI systems.

  15. Sub-surface terahertz imaging through uneven surfaces: visualizing Neolithic wall paintings in Çatalhöyük. (United States)

    Walker, Gillian C; Bowen, John W; Matthews, Wendy; Roychowdhury, Soumali; Labaune, Julien; Mourou, Gerard; Menu, Michel; Hodder, Ian; Jackson, J Bianca


    Pulsed terahertz imaging is being developed as a technique to image obscured mural paintings. Due to significant advances in terahertz technology, portable systems are now capable of operating in unregulated environments and this has prompted their use on archaeological excavations. August 2011 saw the first use of pulsed terahertz imaging at the archaeological site of Çatalhöyük, Turkey, where mural paintings dating from the Neolithic period are continuously being uncovered by archaeologists. In these particular paintings the paint is applied onto an uneven surface, and then covered by an equally uneven surface. Traditional terahertz data analysis has proven unsuccessful at sub-surface imaging of these paintings due to the effect of these uneven surfaces. For the first time, an image processing technique is presented, based around Gaussian beam-mode coupling, which enables the visualization of the obscured painting.

  16. Semiconductor terahertz technology devices and systems at room temperature operation

    CERN Document Server

    Carpintero, G; Hartnagel, H; Preu, S; Raisanen, A


    Key advances in Semiconductor Terahertz (THz) Technology now promises important new applications enabling scientists and engineers to overcome the challenges of accessing the so-called "terahertz gap".  This pioneering reference explains the fundamental methods and surveys innovative techniques in the generation, detection and processing of THz waves with solid-state devices, as well as illustrating their potential applications in security and telecommunications, among other fields. With contributions from leading experts, Semiconductor Terahertz Technology: Devices and Systems at Room Tempe

  17. Fibre laser based broadband THz imaging systems

    DEFF Research Database (Denmark)

    Eichhorn, Finn

    State-of-the-art optical fiber technology can contribute towards complex multi-element broadband terahertz imaging systems. Classical table-top terahertz imaging systems are generally limited to a single emitter/receiver pair, which constrains their imaging capability to tedious raster scanning...... imaging techniques. This thesis exhibits that fiber technology can improve the robustness and the flexibility of terahertz imaging systems both by the use of fiber-optic light sources and the employment of optical fibers as light distribution medium. The main focus is placed on multi-element terahertz...

  18. Terahertz time-lapse imaging of hydration in physiological tissues (United States)

    Bennett, David B.; Taylor, Zachary D.; Bajwa, Neha; Tewari, Priyamvada; Maccabi, Ashkan; Sung, Shijun; Singh, Rahul S.; Culjat, Martin O.; Grundfest, Warren S.; Brown, Elliott R.


    This study describes terahertz (THz) imaging of hydration changes in physiological tissues with high water concentration sensitivity. A fast-scanning, pulsed THz imaging system (centered at 525 GHz; 125 GHz bandwidth) was utilized to acquire a 35 mm x 35 mm field-of-view with 0.5 mm x 0.5 mm pixels in less than two minutes. THz time-lapsed images were taken on three sample systems: (1) a simple binary system of water evaporating from a polypropylene towel, (2) the accumulation of fluid at the site of a sulfuric acid burn on ex vivo porcine skin, and (3) the evaporative dehydration of an ex vivo porcine cornea. The diffusion-regulating behavior of corneal tissue is elucidated, and the correlation of THz reflectivity with tissue hydration is measured using THz spectroscopy on four ex vivo corneas. We conclude that THz imaging can discern small differences in the distribution of water in physiological tissues and is a good candidate for burn and corneal imaging.

  19. Continuous wave terahertz transmission imaging of nonmelanoma skin cancers. (United States)

    Joseph, Cecil S; Yaroslavsky, Anna N; Neel, Victor A; Goyette, Thomas M; Giles, Robert H


    Continuous wave terahertz imaging has the potential to offer a safe, noninvasive medical imaging modality for delineating human skin cancers. Terahertz pulse imaging (TPI) has already shown that there is contrast between basal cell carcinoma and normal skin. Continuous-wave imaging offers a simpler, lower cost alternative to TPI. The goal of this study was to investigate the feasibility of continuous wave terahertz imaging for delineating skin cancers by demonstrating contrast between cancerous and normal tissue in transmission mode. Two CO(2) optically pumped far-infrared molecular gas lasers were used for illuminating the tissue at two frequencies, 1.39 and 1.63 THz. The transmitted signals were detected using a liquid Helium cooled Silicon bolometer. Fresh skin cancer specimens were obtained from Mohs surgeries. The samples were processed and imaged within 24 hours after surgery. During the imaging experiment the samples were kept in pH-balanced saline to prevent tissue dehydration. At both THz frequencies two-dimensional THz transmission images of nonmelanoma skin cancers were acquired with spatial resolution of 0.39 mm at 1.4 THz and 0.49 mm at 1.6 THz. For evaluation purposes, hematoxylin and eosin (H&E) histology was processed from the imaged tissue. A total of 10 specimens were imaged and it was determined that for both frequencies, the areas of decreased transmission in the THz image correlated well with cancerous areas in the histopathology. Two negative controls were also imaged. The difference in transmission between normal and cancerous tissue was found to be approximately 60% at both frequencies, which suggests that contrast between normal and cancerous tissue at these frequencies is dominated by differences in water content. Our results suggest that intraoperative delineation of nonmelanoma skin cancers using continuous-wave terahertz imaging is feasible. Copyright © 2011 Wiley-Liss, Inc.

  20. Identification of tooth abnormalities using terahertz imaging and spectroscopy (United States)

    Zinov'ev, Nickolay N.; Sudworth, Caroline D.; Berry, Elizabeth; Strafford, Saimon M.; Wood, David J.; Carmichael, Fiona A.; Miles, Robert E.; Smith, Michael A.; Chamberlain, J. M.


    Terahertz frequency spectroscopic imaging studies of teeth are reported. The aim is to establish the characteristic properties of enamel and dentine at these high frequencies. Changes to the THz characteristics as a result of various types of tooth abnormalities are reported showing the potential of this technique for dental diagnosis

  1. Signal-Conditioning Block of a 1 × 200 CMOS Detector Array for a Terahertz Real-Time Imaging System

    Directory of Open Access Journals (Sweden)

    Jong-Ryul Yang


    Full Text Available A signal conditioning block of a 1 × 200 Complementary Metal-Oxide-Semiconductor (CMOS detector array is proposed to be employed with a real-time 0.2 THz imaging system for inspecting large areas. The plasmonic CMOS detector array whose pixel size including an integrated antenna is comparable to the wavelength of the THz wave for the imaging system, inevitably carries wide pixel-to-pixel variation. To make the variant outputs from the array uniform, the proposed signal conditioning block calibrates the responsivity of each pixel by controlling the gate bias of each detector and the voltage gain of the lock-in amplifiers in the block. The gate bias of each detector is modulated to 1 MHz to improve the signal-to-noise ratio of the imaging system via the electrical modulation by the conditioning block. In addition, direct current (DC offsets of the detectors in the array are cancelled by initializing the output voltage level from the block. Real-time imaging using the proposed signal conditioning block is demonstrated by obtaining images at the rate of 19.2 frame-per-sec of an object moving on the conveyor belt with a scan width of 20 cm and a scan speed of 25 cm/s.

  2. Applications of terahertz (THz) technology to medical imaging (United States)

    Arnone, Donald D.; Ciesla, Craig M.; Corchia, Alessandra; Egusa, S.; Pepper, Michael; Chamberlain, J. Martyn; Bezant, C.; Linfield, Edmund H.; Clothier, R.; Khammo, N.


    An imaging system has been developed based on pulses of Terahertz (THz) radiation generated and detected using all- optical effects accessed by irradiating semiconductors with ultrafast pulses of visible laser light. This technique, commonly referred to as T-Ray Imaging or THz Pulse Imaging (TPI), holds enormous promise for certain aspects of medical imaging. We have conducted an initial survey of possible medical applications of TPI and demonstrated that TPI images show good contrast between different animal tissue types. Moreover, the diagnostic power of TPI has been elicidated by the spectra available at each pixel in the image, which are markedly different for the different tissue types. This suggests that the spectral information inherent in TPI might be used to identify the type of soft and hard tissue at each pixel in an image and provide other diagnostic information not afforded by conventional imagin techniques. Preliminary TPI studies of pork skin show that 3D tomographic imaging of the skin surface and thickness is possible, and data from experiments on models of the human dermis are presented which demonstrate that different constituents of skin have different refractive indices. Lastly, we present the first THz image of human tissue, namely an extracted tooth. The time of flight of THz pulses through the tooth allows the thickness of the enamel to be determined, and is used to create an image showing the enamel and dentine regions. Absorption of THz pulses in the tooth allows the pulp cavity region to be identified. Initial evidence strongly suggests that TPI my be used to provide valuable diagnostic information pertaining to the enamel, dentine, and the pump cavity.

  3. Contrast-enhanced continuous-terahertz-wave imaging based on superparamagnetic iron oxide nanoparticles for biomedical applications. (United States)

    Zhang, Rui; Zhang, Liangliang; Wu, Tong; Zuo, Shasha; Wang, Ruixue; Zhang, Cunlin; Zhang, Jue; Fang, Jing


    We present a novel contrast-enhanced continuous-terahertz-wave imaging modality based on magnetic induction heating of superparamagnetic iron oxide nanoparticles (SPIOs), which yields a highly sensitive increment in the reflection terahertz (THz) signal in SPIO solution upon exposure to an alternating magnetic field. In the differential and relative refection change focal-plane images before and after alternating magnetic field exposure, a dramatic contrast is demonstrated between water with and without SPIOs. This low-cost, simple, and stable contrast-enhanced continuous-THz-wave imaging system is suitable for miniaturization and real-time imaging application.

  4. Experiments on terahertz 3D scanning microscopic imaging (United States)

    Zhou, Yi; Li, Qi


    Compared with the visible light and infrared, terahertz (THz) radiation can penetrate nonpolar and nonmetallic materials. There are many studies on the THz coaxial transmission confocal microscopy currently. But few researches on the THz dual-axis reflective confocal microscopy were reported. In this paper, we utilized a dual-axis reflective confocal scanning microscope working at 2.52 THz. In contrast with the THz coaxial transmission confocal microscope, the microscope adopted in this paper can attain higher axial resolution at the expense of reduced lateral resolution, revealing more satisfying 3D imaging capability. Objects such as Chinese characters "Zhong-Hua" written in paper with a pencil and a combined sheet metal which has three layers were scanned. The experimental results indicate that the system can extract two Chinese characters "Zhong," "Hua" or three layers of the combined sheet metal. It can be predicted that the microscope can be applied to biology, medicine and other fields in the future due to its favorable 3D imaging capability.

  5. Circular polarization terahertz imaging of nonmelanoma skin cancers (United States)

    Martin, Jillian P.

    The use of terahertz (THz) radiation for imaging human tissue and delineating tumor margins has become an appealing topic in the biomedical field because THz radiation is non-ionizing and has the demonstrated ability to differentiate between cancerous and normal tissue without the need for exogenous contrast agents. Previously, a reflective continuous-wave (CW) THz imaging system utilizing a linear polarization-sensitive detection technique was demonstrated and used to delineate tumor margins for nonmelanoma skin cancers [1, 2] and determine reflectivity differences between normal and cancerous colon tissue [3 - 5]. This detection technique involves illuminating ex vivo tissue samples with linearly polarized light and collecting the signal remitted by the sample after passing through an analyzing wire grid polarizer oriented with its transmission axis perpendicular to the linear polarization incident on the sample. By collecting the cross-polarization signal, the strong Fresnel surface reflections from the sample holder interfaces are eliminated and predominantly signal from within the tissue volume is obtained. The aim of the proposed research is to enhance this polarization-sensitive detection technique by incorporating circular polarization illumination and detection channels. This technique has been demonstrated at optical wavelengths [6], where the scattering of light within the tissue volume has been extensively studied; however, it has yet to be implemented using THz radiation. In addition, this detection technique has the potential to demonstrate increased contrast between cancerous and normal tissue, and experimental results may shed light on the mechanism behind the observed contrast.

  6. Experimental imaging research on continuous-wave terahertz in-line digital holography (United States)

    Huang, Haochong; Wang, Dayong; Rong, Lu; Wang, Yunxin


    The terahertz (THz) imaging is an advanced technique on the basis of the unique characteristics of terahertz radiation. Due to its noncontact, non-invasive and high-resolution capabilities, it has already shown great application prospects in biomedical observation, sample measurement, and quality control. The continuous-wave terahertz in-line digital holography is a combination of terahertz technology and in-line digital holography of which the source is a continuous-wave terahertz laser. Over the past decade, many researchers used different terahertz sources and detectors to undertake experiments. In this paper, the pre-process of the hologram is accomplished after the holograms' recording process because of the negative pixels in the pyroelectric detector and the air vibration caused by the chopper inside the camera. To improve the quality of images, the phase retrieval algorithm is applied to eliminate the twin images. In the experiment, the pin which terahertz wave can't penetrate and the TPX slice carved letters "THz" are chosen for the samples. The amplitude and phase images of samples are obtained and the twin image and noise in the reconstructed images are suppressed. The results validate the feasibility of the terahertz in-line digital holographic imaging technique. This work also shows the terahertz in-line digital holography technique's prospects in materials science and biological samples' detection.

  7. Inspection of plastic weld joints with terahertz imaging (United States)

    Wietzke, S.; Krumbholz, N.; Jördens, C.; Baudrit, B.; Bastian, M.; Koch, M.


    Polymers cover the whole range from commodities to high-tech applications. Plastic products have also gained in importance for construction purposes. This draws the attention to joining techniques like welding. Common evaluation of the weld quality is mostly mechanical and destructive. Existing non-destructive techniques are mostly not entirely reliable or economically inefficient. Here, we demonstrate the potential of terahertz time-domain spectroscopy imaging as a non-destructive testing tool for the inspection of plastic weld joints. High-density polyethylene sheets welded in a lap joint with varying quality serve as samples for terahertz transmission measurements. Imperfections within the weld contact area can clearly be detected by displaying the transmitted intensity in a limited frequency range. Contaminations such as metal or sand are identified since they differ significantly from the polymer in the terahertz image. Furthermore, this new and promising technique is capable of detecting the boundaries of a weld contact area. Aside from revealing a contrast between a proper weld joint and no material connection, the size of an air gap between two plastic sheets can be determined by considering the characteristic frequency-dependent transmission through the structure: The spectral positions of the maxima and minima allow for the calculation of the air layer thickness.

  8. Terahertz spectroscopy applied to food model systems

    DEFF Research Database (Denmark)

    Møller, Uffe

    Water plays a crucial role in the quality of food. Apart from the natural water content of a food product, the state of that water is very important. Water can be found integrated into the biological material or it can be added during production of the product. Currently it is difficult to differ...... to differentiate between these types of water in subsequent quality controls. This thesis describes terahertz time-domain spectroscopy applied on aqueous food model systems, with particular focus on ethanol-water mixtures and confined water pools in inverse micelles.......Water plays a crucial role in the quality of food. Apart from the natural water content of a food product, the state of that water is very important. Water can be found integrated into the biological material or it can be added during production of the product. Currently it is difficult...

  9. Terahertz pulse imaging in reflection geometry of human skin cancer and skin tissue

    Energy Technology Data Exchange (ETDEWEB)

    Woodward, Ruth M [Cavendish Laboratory, University of Cambridge, Madingley Road, Cambridge (United Kingdom); Cole, Bryan E [TeraView Limited, 302/304 Cambridge Science Park, Milton Road, Cambridge (United Kingdom); Wallace, Vincent P [TeraView Limited, 302/304 Cambridge Science Park, Milton Road, Cambridge (United Kingdom); Pye, Richard J [Department of Dermatology, Addenbrooke' s Hospital, Cambridge (United Kingdom); Arnone, Donald D [TeraView Limited, 302/304 Cambridge Science Park, Milton Road, Cambridge (United Kingdom); Linfield, Edmund H [Cavendish Laboratory, University of Cambridge, Madingley Road, Cambridge (United Kingdom); Pepper, Michael [Cavendish Laboratory, University of Cambridge, Madingley Road, Cambridge (United Kingdom)


    We demonstrate the application of terahertz pulse imaging (TPI) in reflection geometry for the study of skin tissue and related cancers both in vitro and in vivo. The sensitivity of terahertz radiation to polar molecules, such as water, makes TPI suitable for studying the hydration levels in the skin and the determination of the lateral spread of skin cancer pre-operatively. By studying the terahertz pulse shape in the time domain we have been able to differentiate between diseased and normal tissue for the study of basal cell carcinoma (BCC). Basal cell carcinoma has shown a positive terahertz contrast, and inflammation and scar tissue a negative terahertz contrast compared to normal tissue. In vivo measurements on the stratum corneum have enabled visualization of the stratum corneum-epidermis interface and the study of skin hydration levels. These results demonstrate the potential of terahertz pulse imaging for the study of skin tissue and its related disorders, both in vitro and in vivo.

  10. Terahertz pulsed imaging as an advanced characterisation tool for film coatings--a review

    DEFF Research Database (Denmark)

    Haaser, Miriam; Gordon, Keith C; Strachan, Clare J


    Solid dosage forms are the pharmaceutical drug delivery systems of choice for oral drug delivery. These solid dosage forms are often coated to modify the physico-chemical properties of the active pharmaceutical ingredients (APIs), in particular to alter release kinetics. Since the product...... performance of coated dosage forms is a function of their critical coating attributes, including coating thickness, uniformity, and density, more advanced quality control techniques than weight gain are required. A recently introduced non-destructive method to quantitatively characterise coating quality...... is terahertz pulsed imaging (TPI). The ability of terahertz radiation to penetrate many pharmaceutical materials enables structural features of coated solid dosage forms to be probed at depth, which is not readily achievable with other established imaging techniques, e.g. near-infrared (NIR) and Raman...

  11. EDITORIAL: Terahertz nanotechnology Terahertz nanotechnology (United States)

    Demming, Anna; Tonouchi, Masayoshi; Reno, John L.


    A useful synergy is being established between terahertz research and nanotechnology. High power sources [1-3] and detectors [4] in what was once considered the terahertz 'frequency gap' [5] in the electromagnetic spectrum have stimulated research with huge potential benefits in a range of industries including food, medicine and security, as well as fundamental physics and astrophysics. This special section, with guest editors Masayoshi Tonouchi and John Reno, gives a glimpse of the new horizons nanotechnology is broaching in terahertz research. While the wavelengths relevant to the terahertz domain range from hundreds of micrometres to millimetres, structures at the nanoscale reveal interesting low energy dynamics in this region. As a result terahertz spectroscopy techniques are becoming increasingly important in nanomaterial characterization, as demonstrated in this special section by colleagues at the University of Oxford in the UK and the Australian National University. They use terahertz spectroscopy to identify the best nanostructure parameters for specific applications [6]. The low energy dynamics in nanostructures also makes them valuable tools for terahertz detection [7]. In addition the much sought after terahertz detection over broadband frequency ranges has been demonstrated, providing versatility that has been greatly in demand, particularly in spectroscopy applications [8, 9]. Also in this special section, researchers in Germany and China tackle some of the coupling issues in terahertz time domain spectroscopy with an emitter specifically well suited for systems operated with an amplified fibre [3]. 'In medical imaging, the advantage of THz radiation is safety, because its energy is much lower than the ionization energy of biological molecules, in contrast to hazardous x-ray radiation,' explains Joo-Hiuk Son from the University of Seoul in Korea in his review [10]. As he also points out, the rotational and vibrational energies of water molecules are

  12. Real-time broadband terahertz spectroscopic imaging by using a high-sensitivity terahertz camera (United States)

    Kanda, Natsuki; Konishi, Kuniaki; Nemoto, Natsuki; Midorikawa, Katsumi; Kuwata-Gonokami, Makoto


    Terahertz (THz) imaging has a strong potential for applications because many molecules have fingerprint spectra in this frequency region. Spectroscopic imaging in the THz region is a promising technique to fully exploit this characteristic. However, the performance of conventional techniques is restricted by the requirement of multidimensional scanning, which implies an image data acquisition time of several minutes. In this study, we propose and demonstrate a novel broadband THz spectroscopic imaging method that enables real-time image acquisition using a high-sensitivity THz camera. By exploiting the two-dimensionality of the detector, a broadband multi-channel spectrometer near 1 THz was constructed with a reflection type diffraction grating and a high-power THz source. To demonstrate the advantages of the developed technique, we performed molecule-specific imaging and high-speed acquisition of two-dimensional (2D) images. Two different sugar molecules (lactose and D-fructose) were identified with fingerprint spectra, and their distributions in one-dimensional space were obtained at a fast video rate (15 frames per second). Combined with the one-dimensional (1D) mechanical scanning of the sample, two-dimensional molecule-specific images can be obtained only in a few seconds. Our method can be applied in various important fields such as security and biomedicine.

  13. Terahertz (THz) Wireless Systems for Space Applications (United States)

    Hwu, Shian U.; deSilva, Kanishka B.; Jih, Cindy T.


    NASA has been leading the Terahertz (THz) technology development for the sensors and instruments in astronomy in the past 20 years. THz technologies are expanding into much broader applications in recent years. Due to the vast available multiple gigahertz (GHz) broad bandwidths, THz radios offer the possibility for wireless transmission of high data rates. Multi-Gigabits per second (MGbps) broadband wireless access based on THz waves are closer to reality. The THz signal high atmosphere attenuation could significantly decrease the communication ranges and transmittable data rates for the ground systems. Contrary to the THz applications on the ground, the space applications in the atmosphere free environment do not suffer the atmosphere attenuation. The manufacturing technologies for the THz electronic components are advancing and maturing. There is great potential for the NASA future high data wireless applications in environments with difficult cabling and size/weight constraints. In this study, the THz wireless systems for potential space applications were investigated. The applicability of THz systems for space applications was analyzed. The link analysis indicates that MGbps data rates are achievable with compact sized high gain antennas.

  14. Microelectromechanical systems bimaterial terahertz sensor with integrated metamaterial absorber. (United States)

    Alves, Fabio; Grbovic, Dragoslav; Kearney, Brian; Karunasiri, Gamani


    This Letter describes the fabrication of a microelectromechanical systems (MEMS) bimaterial terahertz (THz) sensor operating at 3.8 THz. The incident THz radiation is absorbed by a metamaterial structure integrated with the bimaterial. The absorber was designed with a resonant frequency matching the quantum cascade laser illumination source while simultaneously providing structural support, desired thermomechanical properties and optical readout access. Measurement showed that the fabricated absorber has nearly 90% absorption at 3.8 THz. A responsivity of 0.1°/μW and a time constant of 14 ms were observed. The use of metamaterial absorbers allows for tuning the sensor response to the desired frequency to achieve high sensitivity for potential THz imaging applications.

  15. A non-destructive method for quality control of the pellet distribution within a MUPS tablet by terahertz pulsed imaging

    DEFF Research Database (Denmark)

    Novikova, Anna; Markl, Daniel; Axel Zeitler, J


    Terahertz pulsed imaging (TPI) was applied to analyse the inner structure of multiple unit pellet system (MUPS) tablets. MUPS tablets containing different amounts of theophylline pellets coated with Eudragit® NE 30 D and with microcrystalline cellulose (MCC) as cushioning agent were analysed. The...

  16. Terahertz sources

    National Research Council Canada - National Science Library

    Shumyatsky, Pavel; Alfano, Robert R


    We present an overview and history of terahertz (THz) sources for readers of the biomedical and optical community for applications in physics, biology, chemistry, medicine, imaging, and spectroscopy...

  17. Subwavelength terahertz imaging with graphene hyperlens

    DEFF Research Database (Denmark)

    Andryieuski, Andrei; Lavrinenko, Andrei


    of the homogeneous medium approach. Our numerical simulations in COMSOL and CST Microwave Studio confirm the subwavelength imaging properties of the graphene hyperlens. An example of magnification of two point sources separated by λ/5 to the size of few wavelength, which then can be detected with conventional optics...

  18. Dielectric Covered Planar Antennas at Submillimeter Wavelengths for Terahertz Imaging (United States)

    Chattopadhyay, Goutam; Gill, John J.; Skalare, Anders; Lee, Choonsup; Llombart, Nuria; Siegel, Peter H.


    -wave and terahertz bands: a) Antenna fabrication compatible with lithographic techniques. b) Much simpler fabrication of the lens. c) A simple quarter-wavelength matching layer of the lens will be more efficient if a smaller portion of the lens is used. d) The directivity is given by the lens diameter instead of the leaky pole (the bandwidth will not depend anymore on the directivity but just on the initial cavity). The feed is a standard waveguide, which is compatible with proven Schottky diode mixer/detector technologies. The development of such technology will benefit applications where submillimeter- wave heterodyne array designs are required. The main fields are national security, planetary exploration, and biomedicine. For national security, wideband submillimeter radars could be an effective tool for the standoff detection of hidden weapons or bombs concealed by clothing or packaging. In the field of planetary exploration, wideband submillimeter radars can be used as a spectrometer to detect trace concentrations of chemicals in atmospheres that are too cold to rely on thermal imaging techniques. In biomedicine, an imaging heterodyne system could be helpful in detecting skin diseases.

  19. Processing and fusion of passively acquired, millimeter and terahertz images of the human body (United States)

    Tian, Li; Shen, Yanchun; Jin, Weiqi; Zhao, Guozhong; Cai, Yi


    A passive, millimeter wave (MMW) and terahertz (THz) dual-band imaging system composed of 94 and 250 GHz single-element detectors was used to investigate preprocessing and fusion algorithms for dual-band images. Subsequently, an MMW and THz image preprocessing and fusion integrated algorithm (MMW-THz IPFIA) was developed. In the algorithm, a block-matching and three-dimensional filtering denoising algorithm is employed to filter noise, an adaptive histogram equalization algorithm to enhance images, an intensity-based registration algorithm to register images, and a wavelet-based image fusion algorithm to fuse the preprocessed images. The performance of the algorithm was analyzed by calculating the SNR and information entropy of the actual images. This algorithm effectively reduces the image noise and improves the level of detail in the images. Since the algorithm improves the performance of the investigated imaging system, it should support practical technological applications. Because the system responds to blackbody radiation, its improvement is quantified herein using the static performance parameter commonly employed for thermal imaging systems, namely, the minimum detectable temperature difference (MDTD). An experiment was conducted in which the system's MDTD was measured before and after applying the MMW-THz IPFIA, verifying the improved performance that can be realized through its application.

  20. Terahertz imaging for early screening of diabetic foot syndrome: A proof of concept (United States)

    Hernandez-Cardoso, G. G.; Rojas-Landeros, S. C.; Alfaro-Gomez, M.; Hernandez-Serrano, A. I.; Salas-Gutierrez, I.; Lemus-Bedolla, E.; Castillo-Guzman, A. R.; Lopez-Lemus, H. L.; Castro-Camus, E.


    Most people with diabetes suffer some deterioration of the feet. Diabetic foot syndrome causes ulceration in about 15% of cases and such deterioration leads to amputation in about 2.5% of diabetic patients, diminishing their quality of life and generating extraordinary costs for patients and public health systems. Currently, there is no objective method for the detection of diabetic foot syndrome in its early stages. We propose terahertz imaging as a method for the evaluation of such deterioration. This screening method could aid the prevention and medical treatment of this condition in the future.

  1. A general approach to low noise readout of terahertz imaging arrays. (United States)

    Chisum, Jonathan D; Grossman, Erich N; Popović, Zoya


    This article describes the theory and design of an ultra-low noise electronic readout circuit for use with room temperature video-rate terahertz imaging arrays. First, the noise characteristics of various imaging detectors, including low resistance bolometers and high resistance diodes are discussed. Theoretical approaches to white and 1/f noise mitigation are examined, and a corresponding low-noise readout circuit is designed, built, and tested. It is shown that the circuit is capable of achieving detector limited noise performance for use in room temperature terahertz imaging systems. A thorough noise analysis of the circuit provides the necessary information for applying the readout circuit to any type of imaging detector, and more generally, any measurement of small signals from various source impedances in the presence of white and 1/f noise. W-band measurements of an 8-element, high-resistance detector array, and a 32-element, low-resistance detector array demonstrate the usefulness of the readout circuit. Finally, recommended circuit configurations for various detectors in the literature are provided, with theoretical performance metrics summarized. © 2011 American Institute of Physics

  2. High-sensitivity attenuated total internal reflection continuous-wave terahertz imaging (United States)

    Liu, Hongxiang; Wang, Yuye; Xu, Degang; Wu, Limin; Yan, Chao; Yan, Dexian; Tang, Longhuang; He, Yixin; Feng, Hua; Yao, Jianquan


    We demonstrate an attenuated total internal reflection imaging system. The surface information of the sample on top of a prism can be acquired by two-dimensionally scanning this prism moving in the vertical plane with horizontally incident continuous terahertz waves at a fixed height. The principles and feasibility of this method are investigated. The effective imaging area on the prism, image resolution and polarization dependence of contrast enhancement and stability improvement are analyzed. Examples including solid agar, distilled water and porcine tissue are presented, demonstrating the method’s advantages of high sensitivity and simple sample preparation. The experimental and theoretical results consistently show that p-polarization contributes to enhanced image contrast and more stable intensity of the attenuated total internal reflected signal.

  3. Multichannel terahertz time-domain spectroscopy system at 1030 nm excitation wavelength. (United States)

    Brahm, Anika; Wilms, Annika; Dietz, Roman J B; Göbel, Thorsten; Schell, Martin; Notni, Gunther; Tünnermann, Andreas


    We present Terahertz (THz) imaging with a 1D multichannel time-domain spectroscopy (TDS) system which operates with a photoconductive array of 15 detection channels excited by a 1030 nm femtosecond fiber laser. The emitter and detector are photoconductive antennas based on InGaAs/InAlAs multi-layer heterostructures (MLHS). We characterized the THz optics and the resolution of the system. The performance is demonstrated by the multichannel imaging of two samples. A simultaneous measurement of 15 THz pulses with a pixel pitch of 1 mm increases the measurement speed of the TDS system by factor 15.

  4. Terahertz Detection and Imaging Using Graphene Ballistic Rectifiers. (United States)

    Auton, Gregory; But, Dmytro B; Zhang, Jiawei; Hill, Ernie; Coquillat, Dominique; Consejo, Christophe; Nouvel, Philippe; Knap, Wojciech; Varani, Luca; Teppe, Frederic; Torres, Jeremie; Song, Aimin


    A graphene ballistic rectifier is used in conjunction with an antenna to demonstrate a rectenna as a terahertz (THz) detector. A small-area (<1 μm 2 ) local gate is used to adjust the Fermi level in the device to optimize the output while minimizing the impact on the cutoff frequency. The device operates in both n- and p-type transport regimes and shows a peak extrinsic responsivity of 764 V/W and a corresponding noise equivalent power of 34 pW Hz -1/2 at room temperature with no indications of a cutoff frequency up to 0.45 THz. The device also demonstrates a linear response for more than 3 orders of magnitude of input power due to its zero threshold voltage, quadratic current-voltage characteristics and high saturation current. Finally, the device is used to take an image of an optically opaque object at 0.685 THz, demonstrating potential in both medical and security imaging applications.

  5. Detection of Terahertz Radiation

    DEFF Research Database (Denmark)


    The present invention relates to a system for detecting terahertz radiation, a camera device, and a method for detecting terahertz radiation.......The present invention relates to a system for detecting terahertz radiation, a camera device, and a method for detecting terahertz radiation....

  6. A High Precision Terahertz Wave Image Reconstruction Algorithm

    National Research Council Canada - National Science Library

    Guo, Qijia; Chang, Tianying; Geng, Guoshuai; Jia, Chengyan; Cui, Hong-Liang


    With the development of terahertz (THz) technology, the applications of this spectrum have become increasingly wide-ranging, in areas such as non-destructive testing, security applications and medical scanning, in which one of the most...

  7. Comparison of digital beamforming algorithms for 3-D terahertz imaging with sparse multistatic line arrays

    Directory of Open Access Journals (Sweden)

    B. Baccouche


    Full Text Available In this contribution we compare the back-projection algorithm with our recently developed modified range migration algorithm for 3-D terahertz imaging using sparse multistatic line arrays. A 2-D planar sampling scheme is generated using the array's aperture in combination with an orthogonal synthetic aperture obtained through linear movement of the object under test. A stepped frequency continuous wave signal modulation is used for range focusing. Comparisons of the focusing quality show that results using the modified range migration algorithm reflect these of the back-projection algorithm except for some degradation along the array's axis due to the operation in the array's near-field. Nevertheless the highest computational efficiency is obtained from the modified range migration algorithm, which is better than the numerically optimized version of the back-projection algorithm. Measurements have been performed by using an imaging system operating in the W frequency band to verify the theoretical results.

  8. A Data Processing Chain for Terahertz Imaging and Its Use in Artwork Diagnostics (United States)

    Catapano, Ilaria; Soldovieri, Francesco


    The effectiveness of terahertz (THz) imaging is dependent not only on the performances of the adopted hardware technology but also on the data processing approaches adopted by the users to elaborate the measured waveforms and obtain from them clear images of the object under test. With respect to data processing, this paper proposes a strategy involving three different steps aimed at reducing noise, filtering out undesired signal introduced by measurement system, and performing surface topography correction. The usefulness of the proposed data processing chain is preliminarily assessed by using data collected on a sample ad hoc prepared in laboratory. Afterward, an ancient mortar specimen, which is decorated by colored stucco, is analyzed by means of the proposed strategy.

  9. Terahertz pulse imaging of stratified architectural materials for cultural heritage studies (United States)

    Jackson, J. Bianca; Labaune, Julien; Mourou, Gérard; Duling, Irl N.; Walker, Gillian; Bowen, John; Menu, Michel


    Terahertz pulse imaging (TPI) is a novel noncontact, nondestructive technique for the examination of cultural heritage artifacts. It has the advantage of broadband spectral range, time-of-flight depth resolution, and penetration through optically opaque materials. Fiber-coupled, portable, time-domain terahertz systems have enabled this technique to move out of the laboratory and into the field. Much like the rings of a tree, stratified architectural materials give the chronology of their environmental and aesthetic history. This work concentrates on laboratory models of stratified mosaics and fresco paintings, specimens extracted from a neolithic excavation site in Catalhoyuk, Turkey, and specimens measured at the medieval Eglise de Saint Jean-Baptiste in Vif, France. Preparatory spectroscopic studies of various composite materials, including lime, gypsum and clay plasters are presented to enhance the interpretation of results and with the intent to aid future computer simulations of the TPI of stratified architectural material. The breadth of the sample range is a demonstration of the cultural demand and public interest in the life history of buildings. The results are an illustration of the potential role of TPI in providing both a chronological history of buildings and in the visualization of obscured wall paintings and mosaics.

  10. A wavefront analyzer for terahertz time-domain spectrometers

    DEFF Research Database (Denmark)

    Abraham, E.; Brossard, M.; Fauche, P.


    We report on the development of a terahertz wavefront sensor able to determine the optical aberrations of a terahertz time-domain spectrometer. The system measures point-by-point the amplitude and phase of the terahertz electric field in a given plane. From this measurement, we reconstruct...... the terahertz wavefront and calculate its Zernike coefficients. In particular, we especially show that the focus spot of the spectrometer suffers from optical aberrations such as remaining defocus, first and second order astigmatisms, as well as spherical aberration. This opens a route to wavefront correction...... for improved terahertz imaging and spectroscopy....

  11. Terahertz deconvolution

    National Research Council Canada - National Science Library

    Walker, Gillian C; Bowen, John W; Labaune, Julien; Jackson, J-Bianca; Hadjiloucas, Sillas; Roberts, John; Mourou, Gerard; Menu, Michel


    The ability to retrieve information from different layers within a stratified sample using terahertz pulsed reflection imaging and spectroscopy has traditionally been resolution limited by the pulse width available...

  12. Terahertz antenna technology for space applications

    CERN Document Server

    Choudhury, Balamati; Jha, Rakesh Mohan


    This book explores the terahertz antenna technology towards implementation of compact, consistent and cheap terahertz sources, as well as the high sensitivity terahertz detectors. The terahertz EM band provides a transition between the electronic and the photonic regions thus adopting important characteristics from these regimes. These characteristics, along with the progress in semiconductor technology, have enabled researchers to exploit hitherto unexplored domains including satellite communication, bio-medical imaging, and security systems. The advances in new materials and nanostructures such as graphene will be helpful in miniaturization of antenna technology while simultaneously maintaining the desired output levels. Terahertz antenna characterization of bandwidth, impedance, polarization, etc. has not yet been methodically structured and it continues to be a major research challenge. This book addresses these issues besides including the advances of terahertz technology in space applications worldwide,...

  13. Graphene hyperlens for terahertz radiation

    DEFF Research Database (Denmark)

    Andryieuski, Andrei; Chigrin, D.; Novitsky, Andrey


    We propose the structured graphene terahertz hyperlens that allows overcoming natural diffraction limit and resolving subwavelength features. The proposed hyperlens can have applications in terahertz spectroscopy and imaging.......We propose the structured graphene terahertz hyperlens that allows overcoming natural diffraction limit and resolving subwavelength features. The proposed hyperlens can have applications in terahertz spectroscopy and imaging....

  14. Time-Domain Terahertz Reflection Holograhic Tomography Nondestructive Evaluation System Project (United States)

    National Aeronautics and Space Administration — We propose to demonstrate key elements of feasibility for a single-sided time-domain terahertz reflection holographic tomographic imaging (TD-THz RHT) nondestructive...

  15. Terahertz time-domain spectroscopy and imaging of artificial RNA

    DEFF Research Database (Denmark)

    Fischer, Bernd M.; Hoffmann, Matthias; Helm, Hanspeter


    We use terahertz time-domain spectroscopy (THz-TDS) to measure the far-infrared dielectric function of two artificial RNA single strands, composed of polyadenylic acid (poly-A) and polycytidylic acid (poly-C). We find a significant difference in the absorption between the two types of RNA strands...

  16. Envelope Correction of Micro-Motion Targets in the Terahertz ISAR Imaging

    Directory of Open Access Journals (Sweden)

    Qi Yang


    Full Text Available Motion compensation is a crucial step to inverse synthetic aperture radar imaging, and envelope correction is the foundation of motion compensation. Research on envelope correction based on the small-angle imaging model has matured after years of development. However, the small-angle imaging model is not applicable to parameter estimation and imaging of micro-motion targets. According to the characteristics of the micro-motion targets and the superiorities of terahertz imaging radar, an envelope correction method for micro-motion targets in the terahertz region was proposed in this paper, including the jump error correction based on periodic correction and drift error compensation based on nonlinear fitting. Then a 330 GHz imaging radar and two experiments on corner reflectors and a warhead model were introduced. The validity of the method was verified by the experimental results, and the performance of the method was proved by the inverse Radon transform of the range profile sequences.

  17. Fra Angelico’s painting technique revealed by terahertz time-domain imaging (THz-TDI)

    DEFF Research Database (Denmark)

    Dandolo, Corinna Ludovica Koch; Picollo, Marcello; Cucci, Costanza


    We have investigated with terahertz time-domain imaging (THz-TDI) the well-known Lamentation over the dead Christ panel painting (San Marco Museum, Florence) painted by Fra Giovanni Angelico within 1436 and 1441. The investigation provided a better understanding of the construction and gilding...

  18. Evaluating the effect of coating equipment on tablet film quality using terahertz pulsed imaging

    DEFF Research Database (Denmark)

    Haaser, Miriam; Naelapaa, Kaisa; Gordon, Keith C


    In this study, terahertz pulsed imaging (TPI) was employed to investigate the effect of the coating equipment (fluid bed and drum coater) on the structure of the applied film coating and subsequent dissolution behaviour. Six tablets from every batch coated with the same delayed release coating fo...

  19. Graphene based metamaterials for terahertz cloaking and subwavelength imaging (United States)

    Forouzmand, Seyedali

    Graphene is a two-dimensional carbon crystal that became one of the most controversial topics of research in the last few years. The intense interest in graphene stems from recent demonstrations of their potentially revolutionary electromagnetic applications -- including negative refraction, subdiffraction imaging, and even invisibility -- which have suggested a wide range of new devices for communications, sensing, and biomedicine. In addition, it has been shown that graphene is amenable to unique patterning schemes such as cutting, bending, folding, and fusion that are predicted to lead to interesting properties. A recent proposed application of graphene is in engineering the scattering properties of objects, which may be leveraged in applications such as radar-cross-section management and stealth, where it may be required to make one object look like another object or render an object completely invisible. We present the analytical formulation for the analysis of electromagnetic interaction with a finite conducting wedge covered with a cylindrically shaped nanostructured graphene metasurface, resulting in the scattering cancellation of the dominant scattering mode for all the incident and all the observation angles. Following this idea, the cylindrical graphene metasurface is utilized for cloaking of several concentric finite conducting wedges. In addition, a wedge shaped metasurface is proposed as an alternative approach for cloaking of finite wedges. The resolution of the conventional imaging lenses is restricted by the natural diffraction limit. Artificially engineered metamaterials now offer the possibility of creating a superlens that overcomes this restriction. We demonstrate that a wire medium (WM) slab loaded with graphene sheets enables the enhancement of the near field for subwavelength imaging at terahertz (THz) frequencies. The analysis is based on the nonlocal homogenization model for WM with the additional boundary condition in the connection of

  20. Three-Dimensional Terahertz Coded-Aperture Imaging Based on Single Input Multiple Output Technology

    Directory of Open Access Journals (Sweden)

    Shuo Chen


    Full Text Available As a promising radar imaging technique, terahertz coded-aperture imaging (TCAI can achieve high-resolution, forward-looking, and staring imaging by producing spatiotemporal independent signals with coded apertures. In this paper, we propose a three-dimensional (3D TCAI architecture based on single input multiple output (SIMO technology, which can reduce the coding and sampling times sharply. The coded aperture applied in the proposed TCAI architecture loads either purposive or random phase modulation factor. In the transmitting process, the purposive phase modulation factor drives the terahertz beam to scan the divided 3D imaging cells. In the receiving process, the random phase modulation factor is adopted to modulate the terahertz wave to be spatiotemporally independent for high resolution. Considering human-scale targets, images of each 3D imaging cell are reconstructed one by one to decompose the global computational complexity, and then are synthesized together to obtain the complete high-resolution image. As for each imaging cell, the multi-resolution imaging method helps to reduce the computational burden on a large-scale reference-signal matrix. The experimental results demonstrate that the proposed architecture can achieve high-resolution imaging with much less time for 3D targets and has great potential in applications such as security screening, nondestructive detection, medical diagnosis, etc.

  1. Contrast in Terahertz Images of Archival Documents—Part I: Influence of the Optical Parameters from the Ink and Support


    Bardon, T.; May, R. K.; Jackson, J. B.; Beentjes, G.; de Bruin, G.; Taday, P. F.; Strlič, M.


    This study aims to objectively inform curators when terahertz time-domain (TD) imaging set in reflection mode is likely to give well-contrasted images of inscriptions in a complex archival document and is a useful non-invasive alternative to current digitisation processes. To this end, the dispersive refractive indices and absorption coefficients from various archival materials are assessed and their influence on contrast in terahertz images from historical documents is explored. Sepia ink an...

  2. Terahertz endoscopic imaging for colorectal cancer detection: Current status and future perspectives. (United States)

    Doradla, Pallavi; Joseph, Cecil; Giles, Robert H


    Terahertz (THz) imaging is progressing as a robust platform for myriad applications in the field of security, health, and material science. The THz regime, which comprises wavelengths spanning from microns to millimeters, is non-ionizing and has very low photon energy: Making it inherently safe for biological imaging. Colorectal cancer is one of the most common causes of death in the world, while the conventional screening and standard of care yet relies exclusively on the physician's experience. Researchers have been working on the development of a flexible THz endoscope, as a potential tool to aid in colorectal cancer screening. This involves building a single-channel THz endoscope, and profiling the THz response from colorectal tissue, and demonstrating endogenous contrast levels between normal and diseased tissue when imaging in reflection modality. The current level of contrast provided by the prototype THz endoscopic system represents a significant step towards clinical endoscopic application of THz technology for in-vivo colorectal cancer screening. The aim of this paper is to provide a short review of the recent advances in THz endoscopic technology and cancer imaging. In particular, the potential of single-channel THz endoscopic imaging for colonic cancer screening will be highlighted.

  3. Characteristic responses of biological and nanoscale systems in the terahertz frequency range

    Energy Technology Data Exchange (ETDEWEB)

    Angeluts, A A; Balakin, A V; Evdokimov, M G; Ozheredov, I A; Sapozhnikov, D A; Solyankin, P M; Shkurinov, A P [International Laser Center, M. V. Lomonosov Moscow State University, Moscow (Russian Federation); Esaulkov, M N; Nazarov, M M [Institute on Laser and Information Technologies, Russian Academy of Sciences, Shatura, Moscow Region (Russian Federation); Cherkasova, O P [Institute of Laser Physics, Siberian Branch, Russian Academy of Sciences, Novosibirsk (Russian Federation)


    This paper briefly examines methods for the generation of pulsed terahertz radiation and principles of pulsed terahertz spectroscopy, an advanced informative method for studies of complex biological and nanostructured systems. Some of its practical applications are described. Using a number of steroid hormones as examples, we demonstrate that terahertz spectroscopy in combination with molecular dynamics methods and computer simulation allows one to gain information about the structure of molecules in crystals. A 'terahertz colour vision' method is proposed for analysis of pulsed terahertz signals reflected from biological tissues and it is shown that this method can be effectively used to analyse the properties of biological tissues and for early skin cancer diagnosis. (laser biophotonics)

  4. Terahertz spectroscopy and imaging for cultural heritage management: state of art and perspectives (United States)

    Catapano, Ilaria; Soldovieri, Francesco


    Non-invasive diagnostic tools able to provide information on the materials and preservation state of artworks are crucial to help conservators, archaeologists and anthropologists to plan and carry out their tasks properly. In this frame, technological solutions exploiting Terahertz (THz) radiation, i.e., working at frequencies ranging from 0.1 to 10 THz, are currently deserving huge attention as complementary techniques to classical analysis methodologies based on electromagnetic radiations from X-rays to mid infrared [1]. The main advantage offered by THz spectroscopy and imaging systems is referred to their capability of providing information useful to determine the construction modality, the history life and the conservation state of artworks as well as to identify previous restoration actions [1,2]. In particular, unlike mid- and near-infrared spectroscopy, which provides fingerprint absorption spectra depending on the intramolecular behavior, THz spectroscopy is related to the structure of the molecules of the investigated object. Hence, it can discriminate, for instance, the different materials mixed in a paint [1,2]. Moreover, THz radiation is able to penetrate several materials which are opaque to both visible and infrared materials, such as varnish, paint, plaster, paper, wood, plastic, and so on. Accordingly, it is useful to detect hidden objects and characterize the inner structure of the artwork under test even in the direction of the depth, while avoiding core drillings. In this frame, THz systems allow us to discriminate different layers of materials present in artworks like paints, to obtain images providing information on the construction technique as well as to discover risk factors affecting the preservation state, such as non-visible cracks, hidden molds and air gaps between the paint layer and underlying structure. Furthermore, adopting a no-ionizing radiation, THz systems offer the not trivial benefit of negligible long term risks to the

  5. Terahertz pulsed imaging of freshly excised human colonic tissues

    Energy Technology Data Exchange (ETDEWEB)

    Reid, Caroline B; Gibson, Adam P [Department of Medical Physics and Bioengineering, University College London, London, WC1E 6BT (United Kingdom); Fitzgerald, Anthony; Wallace, Vincent P [School of Physics, University of Western Australia, Crawley 6009 (Australia); Reese, George; Tekkis, Paris [Division of Surgery, Chelsea and Westminster Campus, Imperial College London, London (United Kingdom); Goldin, Robert [Centre for Pathology, Imperial College London, St Mary' s Campus, London (United Kingdom); O' Kelly, P S [TeraView Ltd, Platinum Building, St John' s Innovation Park, Cowley Road, Cambridge, CB4 0WS (United Kingdom); Pickwell-MacPherson, Emma, E-mail: [Department of Electronic Engineering, Chinese University of Hong Kong, Shatin, NT (Hong Kong)


    We present the results from a feasibility study which measures properties in the terahertz frequency range of excised cancerous, dysplastic and healthy colonic tissues from 30 patients. We compare their absorption and refractive index spectra to identify trends which may enable different tissue types to be distinguished. In addition, we present statistical models based on variations between up to 17 parameters calculated from the reflected time and frequency domain signals of all the measured tissues. These models produce a sensitivity of 82% and a specificity of 77% in distinguishing between healthy and all diseased tissues and a sensitivity of 89% and a specificity of 71% in distinguishing between dysplastic and healthy tissues. The contrast between the tissue types was supported by histological staining studies which showed an increased vascularity in regions of increased terahertz absorption.

  6. Dual-frequency continuous-wave terahertz transmission imaging of nonmelanoma skin cancers (United States)

    Joseph, Cecil S.; Yaroslavsky, Anna N.; Lagraves, Julie L.; Goyette, Thomas M.; Giles, Robert H.


    Continuous wave terahertz imaging has the potential for diagnosing and delineating skin cancers. While contrast has been observed between cancerous and normal tissue at terahertz frequencies, the source mechanism behind this contrast is not clearly understood.1Transmission measurements of 240μm thick sections of nonmelanoma skin cancer were taken at two frequencies of 1.39 THz and 1.63 THz that lie within and outside the tryptophan absorption band, respectively. Two CO2 pumped Far-Infrared molecular gas lasers were used for illuminating the tissue while the transmitted signals were detected using a liquid Helium cooled Silicon bolometer. At both THz frequencies 2-dimensional THz transmission images of nonmelanoma skin cancers were acquired with better than 0.5mm spatial resolution. The resulting images were compared to the sample histology and showed a correlation between cancerous tissue and decreased transmission. The results of the imaging experiments will be presented and discussed.

  7. Terahertz Radome Inspection

    Directory of Open Access Journals (Sweden)

    Fabian Friederich


    Full Text Available Radomes protecting sensitive radar, navigational, and communications equipment of, e.g., aircraft, are strongly exposed to the environment and have to withstand harsh weather conditions and potential impacts. Besides their significance to the structural integrity of the radomes, it is often crucial to optimize the composite structures for best possible radio performance. Hence, there exists a significant interest in non-destructive testing techniques, which can be used for defect inspection of radomes in field use as well as for quality inspection during the manufacturing process. Contactless millimeter-wave and terahertz imaging techniques provide millimeter resolution and have the potential to address both application scenarios. We report on our development of a three-dimensional (3D terahertz imaging system for radome inspection during industrial manufacturing processes. The system was designed for operation within a machining center for radome manufacturing. It simultaneously gathers terahertz depth information in adjacent frequency ranges, from 70 to 110 GHz and from 110 to 170 GHz by combining two frequency modulated continuous-wave terahertz sensing units into a single measurement device. Results from spiraliform image acquisition of a radome test sample demonstrate the successful integration of the measurement system.

  8. Real time imaging analysis using a terahertz quantum cascade laser and a microbolometer focal plane array


    Buchanan, Kevin William.


    It is widely published that the terahertz (THz) spectral range has potential for imaging in the fields of military and security applications. The Sensors Research Laboratory previously achieved real-time imaging of concealed objects using a 1mW quantum cascade laser (QCL) and an uncooled vanadium oxide/silicon nitride based microbolometer. This thesis introduces an amorphous silicon based microbolometer with improved NETD in the 8-12 micrometer infrared spectral range. The QCL is usually oper...

  9. Inspection of panel paintings beneath gilded finishes using terahertz time-domain imaging

    DEFF Research Database (Denmark)

    Dandolo, Corinna Ludovica Koch; Cosentino, Antonino; Jepsen, Peter Uhd


    Scientific analysis of panel paintings could provide key information to art historians and conservators about the composition and condition of the constituent layers. Knowledge of the structure, stratigraphy, and condition of the subsurface layers of these objects is highly relevant to conservation...... of subsurface 3D images and stratigraphic images (B-scans). The technique is contactless and non-invasive, and has been successfully applied to investigation of panel paintings. Regarding gilded panel paintings, the extremely high reflectivity of metals at submillimeter wavelengths generally precludes...... in the terahertz range, due to the skin effect. The thickness of gold leaf, a fraction of a micrometer, matches the skin depth of gold in the terahertz frequency range covered by THz-TDI devices. We therefore investigated and imaged subsurface features of panel paintings through gilded finishes with THz...

  10. Efficient Terahertz Wide-Angle NUFFT-Based Inverse Synthetic Aperture Imaging Considering Spherical Wavefront

    Directory of Open Access Journals (Sweden)

    Jingkun Gao


    Full Text Available An efficient wide-angle inverse synthetic aperture imaging method considering the spherical wavefront effects and suitable for the terahertz band is presented. Firstly, the echo signal model under spherical wave assumption is established, and the detailed wavefront curvature compensation method accelerated by 1D fast Fourier transform (FFT is discussed. Then, to speed up the reconstruction procedure, the fast Gaussian gridding (FGG-based nonuniform FFT (NUFFT is employed to focus the image. Finally, proof-of-principle experiments are carried out and the results are compared with the ones obtained by the convolution back-projection (CBP algorithm. The results demonstrate the effectiveness and the efficiency of the presented method. This imaging method can be directly used in the field of nondestructive detection and can also be used to provide a solution for the calculation of the far-field RCSs (Radar Cross Section of targets in the terahertz regime.

  11. Early detection of germinated wheat grains using terahertz image and chemometrics (United States)

    Jiang, Yuying; Ge, Hongyi; Lian, Feiyu; Zhang, Yuan; Xia, Shanhong


    In this paper, we propose a feasible tool that uses a terahertz (THz) imaging system for identifying wheat grains at different stages of germination. The THz spectra of the main changed components of wheat grains, maltose and starch, which were obtained by THz time spectroscopy, were distinctly different. Used for original data compression and feature extraction, principal component analysis (PCA) revealed the changes that occurred in the inner chemical structure during germination. Two thresholds, one indicating the start of the release of α-amylase and the second when it reaches the steady state, were obtained through the first five score images. Thus, the first five PCs were input for the partial least-squares regression (PLSR), least-squares support vector machine (LS-SVM), and back-propagation neural network (BPNN) models, which were used to classify seven different germination times between 0 and 48 h, with a prediction accuracy of 92.85%, 93.57%, and 90.71%, respectively. The experimental results indicated that the combination of THz imaging technology and chemometrics could be a new effective way to discriminate wheat grains at the early germination stage of approximately 6 h.

  12. Discrimination and identification of RDX/PETN explosives by chemometrics applied to terahertz time-domain spectral imaging (United States)

    Bou-Sleiman, J.; Perraud, J.-B.; Bousquet, B.; Guillet, J.-P.; Palka, N.; Mounaix, P.


    Detection of explosives has always been a priority for homeland security. Jointly, terahertz spectroscopy and imaging are emerging and promising candidates as contactless and safe systems. In this work, we treated data resulting from hyperspectral imaging obtained by THz-time domain spectroscopy, with chemometric tools. We found efficient identification and sorting of targeted explosives in the case of pure and mixture samples. In this aim, we applied to images Principal Component Analysis (PCA) to discriminate between RDX, PETN and mixtures of the two materials, using the absorbance as the key-parameter. Then we applied Partial Least Squares-Discriminant Analysis (PLS-DA) to each pixel of the hyperspectral images to sort the explosives into different classes. The results clearly show successful identification and categorization of the explosives under study.

  13. Uncooled CMOS terahertz imager using a metamaterial absorber and pn diode. (United States)

    Escorcia, Ivonne; Grant, James; Gough, John; Cumming, David R S


    We demonstrate a low-cost uncooled terahertz (THz) imager fabricated in a standard 180 nm CMOS process. The imager is composed of a broadband THz metamaterial absorber coupled with a diode microbolometer sensor where the pn junction is used as a temperature sensitive device. The metamaterial absorber array is integrated in the top metallic layers of a six metal layer process allowing for complete monolithic integration of the metamaterial absorber and sensor. We demonstrate the capability of the detector for stand-off imaging applications by using it to form transmission and reflection images of a metallic object hidden in a manila envelope.

  14. Investigating murals with terahertz reflective tomography (United States)

    Yuan, Minjie; Sun, Wenfeng; Wang, Xinke; Wang, Sen; Zhang, Qunxi; Ye, Jiasheng; Zhang, Yan


    Terahertz time-domain spectroscopy (THz-TDS) imaging technology has been proposed to be used in the non-invasive detection of murals. THz-TDS images provide structural data of the sample that cannot be obtained with other complementary techniques. In this paper, two types of defects hidden in the plaster used to simulate the cases of defects in the murals, have been investigated by the terahertz reflected time domain spectroscopy imaging system. These preset defects include a leaf slice and a slit built in the plaster. With the terahertz reflective tomography, information about defects has been determined involving the thickness from the surface of sample to the built-in defect, the profile and distribution of the defect. With this THz tomography, different defects with the changes of optical thickness and their relative refractive index have been identified. The application of reflective pulsed terahertz imaging has been extended to the defect detection of the murals.

  15. Application of terahertz spectroscopy imaging for discrimination of transgenic rice seeds with chemometrics. (United States)

    Liu, Wei; Liu, Changhong; Hu, Xiaohua; Yang, Jianbo; Zheng, Lei


    Discrimination of genetically modified organisms is increasingly demanded by legislation and consumers worldwide. The feasibility of a non-destructive discrimination of transgenic rice seeds from its non-transgenic counterparts was examined by terahertz spectroscopy imaging system combined with chemometrics. Principal component analysis (PCA), least squares support vector machines (LS-SVM), PCA-back propagation neural network (PCA-BPNN), and random forest (RF) models with the first and second derivative and standard normal variate transformation (SNV) pre-treatments were applied to classify rice seeds based on genotype. The results demonstrated that differences between non-transgenic and transgenic rice seeds did exist, and an excellent classification (accuracy was 96.67% in the prediction set) could be achieved using the RF model combined with the first derivative pre-treatment. The results indicated that THz spectroscopy imaging together with chemometrics would be a promising technique to identify transgenic rice seeds with high efficiency and without any sample preparation. Copyright © 2016 Elsevier Ltd. All rights reserved.

  16. Ionic contrast terahertz time resolved imaging of frog auricular heart muscle electrical activity (United States)

    Masson, Jean-Baptiste; Sauviat, Martin-Pierre; Gallot, Guilhem


    The authors demonstrate the direct, noninvasive and time resolved imaging of functional frog auricular fibers by ionic contrast terahertz (ICT) near field microscopy. This technique provides quantitative, time-dependent measurement of ionic flow during auricular muscle electrical activity, and opens the way of direct noninvasive imaging of cardiac activity under stimulation. ICT microscopy technique was associated with full three-dimensional simulation enabling to measure precisely the fiber sizes. This technique coupled to waveguide technology should provide the grounds to development of advanced in vivo ion flux measurement in mammalian hearts, allowing the prediction of heart attack from change in K+ fluxes.

  17. Terahertz Science, Technology, and Communication (United States)

    Chattopadhyay, Goutam


    The term "terahertz" has been ubiquitous in the arena of technology over the past couple of years. New applications are emerging every day which are exploiting the promises of terahertz - its small wavelength; capability of penetrating dust, clouds, and fog; and possibility of having large instantaneous bandwidth for high-speed communication channels. Until very recently, space-based instruments for astrophysics, planetary science, and Earth science missions have been the primary motivator for the development of terahertz sensors, sources, and systems. However, in recent years the emerging areas such as imaging from space platforms, surveillance of person-borne hidden weapons or contraband from a safe stand-off distance and reconnaissance, medical imaging and DNA sequencing, and in the world high speed communications have been the driving force for this area of research.

  18. Artworks characterization at THz frequencies: preliminary results via the Fiber-Coupled Terahertz Time Domain System (United States)

    Catapano, Ilaria; Soldovieri, Francesco


    In the research field of art and archaeology, scientific observation and analysis are hugely demanded to gather as more information as possible on the materials and techniques used to create artworks as well as in previous restoration actions. In this frame, diagnostic tools exploiting electromagnetic waves deserve massive interest tanks to their ability to provide non-invasive and possibly contactless characterization of the investigated objects. Among the electromagnetic diagnostic technologies, those working at frequencies belonging to the 0.1-10 THz range are currently deserving an increased attention since THz waves are capable of penetrating into optically opaque materials (up to the preparation layers), without direct contact and by involving sufficiently low energy to be considered as perfectly non-invasive in practice [1,2]. Moreover, being THz non-ionizing radiations, a moderate exposure to them implies minor long term risks to the molecular stability of the historical artifact and humans. Finally, recent developments of THz technology have allowed the commercialization of compact, flexible and portable systems. One of them is the Fiber-Coupled Terahertz Time Domain System (FICO) developed by Z-Omega, acquired by the Institute of Electromagnetic Sensing of the Environment (IREA) in 2013. This system works in the range from 60GHz to 3THz with a waveform acquisition speed up to 500Hz, it is equipped with fiber optic coupled transmitting and receiving probes and, few months ago, has been potentiated by means of an automatic positioning system enabling to scan a 150mm x 150mm area. In the frame of the IREA research activities regarding cultural heritage, the FICO system is currently adopted to perform both spectroscopy and imaging, which are the two kind of analysis wherein THz technology can be profitably explored [3]. In particular, THz spectroscopy is used to distinguish different artists materials by exploiting their peculiar fingerprint in the absorption

  19. Reflection terahertz time-domain imaging for analysis of an 18th century neoclassical easel painting

    DEFF Research Database (Denmark)

    Dandolo, Corinna Ludovica Koch; Filtenborg, Troels; Fukunaga, Kaori


    Terahertz time-domain imaging (THz-TDI) has been applied for imaging a hidden portrait and other subsurfacecomposition layers of an 18th century (18C) easel painting by Nicolai Abildgaard, the most important 18CDanish neoclassical painter of historical and mythological subjects. For the first time......, a real hidden portraiton an easel painting has been imaged by THz-TDI, with an unexpected richness of detail. THz C- andB-scans have been compared with images obtained by x-ray radiography and invasive cross-sectional imaging,leading to a deeper understanding of the strengths and limitations...... in practical applications of the technique. Interfaces between layers ofthe painting have been successfully imaged, contributing substantially to the understanding of the structure of the painting....

  20. Application of Terahertz Radiation to the Detection of Corrosion under the Shuttle's Thermal Protection System (United States)

    Madaras, Eric I.; Anastasi, Robert F.; Smith, Stephen W.; Seebo, Jeffrey P.; Walker, James L.; Lomness, Janice K.; Hintze, Paul E.; Kammerer, Catherine C.; Winfree, William P.; Russell, Richard W.


    There is currently no method for detecting corrosion under Shuttle tiles except for the expensive process of tile removal and replacement; hence NASA is investigating new NDE methods for detecting hidden corrosion. Time domain terahertz radiation has been applied to corrosion detection under tiles in samples ranging from small lab samples to a Shuttle with positive results. Terahertz imaging methods have been able to detect corrosion at thicknesses of 5 mils or greater under 1" thick Shuttle tiles and 7-12 mils or greater under 2" thick Shuttle tiles.

  1. Towards terahertz microscopy

    NARCIS (Netherlands)

    Van der Valk, N.C.J.


    Terahertz (=1012 Hz) radiation is a form of electromagnetic radiation that is at this moment used rarely for imaging purposes. However, there are indeed reasons to assume that imaging with terahertz radiation could be very useful. First, many materials, such as paper, plastics and clothing are

  2. 3-dimensional terahertz imaging and analysis of historical art pieces

    DEFF Research Database (Denmark)

    Dandolo, Corinna Ludovica Koch; Jepsen, Peter Uhd

    from a target. Therefore, THz imaging has proven its versatility as a new imaging technology for inspection and analysis of historical as well as contemporary art, offering detailed information about the internal structure of such objects, complementary to information available by other methods...... such as x-ray radiography and infrared imaging. Here we present comprehensive, fully depth-resolved imaging and analysis of a historical wall painting, an easel painting and a gilded panel....

  3. 2D and 3D Terahertz Imaging and X-Rays CT for Sigillography Study (United States)

    Fabre, M.; Durand, R.; Bassel, L.; Recur, B.; Balacey, H.; Bou Sleiman, J.; Perraud, J.-B.; Mounaix, P.


    Seals are part of our cultural heritage but the study of these objects is limited because of their fragility. Terahertz and X-Ray imaging are used to analyze a collection of wax seals from the fourteenth to eighteenth centuries. In this work, both techniques are compared in order to discuss their advantages and limits and their complementarity for conservation state study of the samples. Thanks to 3D analysis and reconstructions, defects and fractures are detected with an estimation of their depth position. The path from the parchment tongue inside the seals is also detected.

  4. Nondestructive evaluation of cork enclosures using terahertz/millimeter wave spectroscopy and imaging. (United States)

    Hor, Yew Li; Federici, John F; Wample, Robert L


    Natural cork enclosures, due to their cell structure, composition, and low moisture are fairly transparent to terahertz (THz) and millimeter waves enabling nondestructive evaluation of the cork's surface and interior. It is shown that the attenuation coefficient of the defect-free cork can be modeled with a Mie scattering model in the weakly scattering limit. Contrast in the THz images is a result of enhanced scattering of THz radiation by defects or voids as well as variations in the cork cell structure. The presence of voids, defects, and changes in grain structure can be determined with roughly 100-300 microm resolution.

  5. Nondestructive Evaluation of Carbon Fiber Reinforced Polymer Composites Using Reflective Terahertz Imaging

    Directory of Open Access Journals (Sweden)

    Jin Zhang


    Full Text Available Terahertz (THz time-domain spectroscopy (TDS imaging is considered a nondestructive evaluation method for composite materials used for examining various defects of carbon fiber reinforced polymer (CFRP composites and fire-retardant coatings in the reflective imaging modality. We demonstrate that hidden defects simulated by Teflon artificial inserts are imaged clearly in the perpendicular polarization mode. The THz TDS technique is also used to measure the thickness of thin fire-retardant coatings on CFRP composites with a typical accuracy of about 10 micrometers. In addition, coating debonding is successfully imaged based on the time-delay difference of the time-domain waveforms between closely adhered and debonded sample locations.

  6. Foreign Object Detection by Sub-Terahertz Quasi-Bessel Beam Imaging

    Directory of Open Access Journals (Sweden)

    Hyang Sook Chun


    Full Text Available Food quality monitoring, particularly foreign object detection, has recently become a critical issue for the food industry. In contrast to X-ray imaging, terahertz imaging can provide a safe and ionizing-radiation-free nondestructive inspection method for foreign object sensing. In this work, a quasi-Bessel beam (QBB known to be nondiffracting was generated by a conical dielectric lens to detect foreign objects in food samples. Using numerical evaluation via the finite-difference time-domain (FDTD method, the beam profiles of a QBB were evaluated and compared with the results obtained via analytical calculation and experimental characterization (knife edge method, point scanning method. The FDTD method enables a more precise estimation of the beam profile. Foreign objects in food samples, namely crickets, were then detected with the QBB, which had a deep focus and a high spatial resolution at 210 GHz. Transmitted images using a Gaussian beam obtained with a conventional lens were compared in the sub-terahertz frequency experimentally with those using a QBB generated using an axicon.

  7. Analysis of 3D Prints by X-ray Computed Microtomography and Terahertz Pulsed Imaging

    DEFF Research Database (Denmark)

    Markl, Daniel; Zeitler, J Axel; Rasch, Cecilie


    PURPOSE: A 3D printer was used to realise compartmental dosage forms containing multiple active pharmaceutical ingredient (API) formulations. This work demonstrates the microstructural characterisation of 3D printed solid dosage forms using X-ray computed microtomography (XμCT) and terahertz pulsed...... imaging (TPI). METHODS: Printing was performed with either polyvinyl alcohol (PVA) or polylactic acid (PLA). The structures were examined by XμCT and TPI. Liquid self-nanoemulsifying drug delivery system (SNEDDS) formulations containing saquinavir and halofantrine were incorporated into the 3D printed...... was characterised by XμCT and TPI on the basis of the computer-aided design (CAD) models of the dosage form (compartmentalised PVA structures were 7.5 ± 0.75% larger than designed; n = 3). CONCLUSIONS: The 3D printer can reproduce specific structures very accurately, whereas the 3D prints can deviate from...

  8. Internal triaxial strain imaging of visibly opaque black rubbers with terahertz polarization spectroscopy

    Directory of Open Access Journals (Sweden)

    Atsuto Moriwaki


    Full Text Available We demonstrate the nondestructive imaging of internal triaxial strain in visibly opaque black rubbers by employing the polarization-sensitive terahertz time-domain spectroscopy (PS THz-TDS technique. From the sample thickness and the differences in amplitude and phase between orthogonal components of the terahertz wave that passed through the sample, the degree of birefringence and the angle of the slow optic axis were determined. We were able to convert the birefringence data into the amount and orientation of the internal strain through a Monte Carlo simulation that correlates the birefringent properties of the rubber with deformation. By comparing the strain map obtained from the PS THz-TDS measurements with that obtained by conventional digital image correlation, we found that both experimental and spatial distributions of the strain are in overall good agreement, except around the clamped sample regions. The deviations result from the intrinsic difference in the obtained strain information between two experiments and it is confirmed that our method based on PS THz-TDS is suited for evaluating the spatial distribution of the internal strain in black rubbers.

  9. Spectral characterization of dielectric materials using terahertz measurement systems (United States)

    Seligman, Jeffrey M.

    The performance of modern high frequency components and electronic systems are often limited by the properties of the materials from which they are made. Over the past decade, there has been an increased emphasis on the development of new, high performance dielectrics for use in high frequency systems. The development of these materials requires novel broadband characterization, instrumentation, and extraction techniques, from which models can be formulated. For this project several types of dielectric sheets were characterized at terahertz (THz) frequencies using quasi-optical (free-space) techniques. These measurement systems included a Fourier Transform Spectrometer (FTS, scalar), a Time Domain Spectrometer (TDS, vector), a Scalar Network Analyzer (SNA), and a THz Vector Network Analyzer (VNA). Using these instruments the THz spectral characteristics of dielectric samples were obtained. Polarization based anisotropy was observed in many of the materials measured using vector systems. The TDS was the most informative and flexible instrument for dielectric characterization at THz frequencies. To our knowledge, this is the first such comprehensive study to be performed. Anisotropy effects within materials that do not come into play at microwave frequencies (e.g. ~10 GHz) were found, in many cases, to increase measured losses at THz frequencies by up to an order of magnitude. The frequency dependent properties obtained during the course of this study included loss tangent, permittivity (index of refraction), and dielectric constant. The results were largely consistent between all the different systems and correlated closely to manufacturer specifications over a wide frequency range (325 GHz-1.5 THz). Anisotropic behavior was observed for some of the materials. Non-destructive evaluation and testing (NDE/NDT) techniques were used throughout. A precision test fixture was developed to accomplish these measurements. Time delay, insertion loss, and S-parameters were

  10. Analysis of a seventeenth-century panel painting by reflection terahertz time-domain imaging (THz-TDI)

    DEFF Research Database (Denmark)

    Dandolo, Corinna Ludovica Koch; Filtenborg, Troels; Skou-Hansen, Jacob


    Terahertz time-domain imaging (THz-TDI) has been applied for nondestructive visualization of a hidden painting and other subsurface composition layers of a seventeenth-century panel painting belonging to the National Gallery of Denmark. Plan-type and cross-sectional scans realized by THz have been...

  11. High Power Quantum Cascade Laser for Terahertz Imaging (United States)


    styrofoam . (a) Digital image of the knife blade to be embedded into a piece of styrofoam . (b) THz QCL illuminated image of the knife blade captured...front-face gold- plated 90-degree f/1 off axis parabolic (OAP) mirror, with exit aperture and focal length of 50 mm to collimate the QCL. The OAP mirror...The second step involved the use of a flat front- plated gold mirror to direct the QCL beam into the external port of the FTIR spectrometer, as shown

  12. Non-invasive terahertz field imaging inside parallel plate waveguides

    DEFF Research Database (Denmark)

    Iwaszczuk, Krzysztof; Andryieuski, Andrei; Lavrinenko, Andrei


    We present a non-invasive broadband air photonic method of imaging of the electric field of THz pulses propagating inside a tapered parallel plate waveguide. The method is based on field-enhanced second harmonic generation of the fundamental laser beam in an external electric field. We apply...

  13. Theoretical and experimental study of high-Q resonant modes in terahertz optical systems

    NARCIS (Netherlands)

    Jellema, Willem; Withington, S.; Trappe, Neil; Murphy, J. A.; Wild, Wolfgang


    The existence of multiple reflections in terahertz optical system causes numerous problems in applications ranging from astronomical to medical instrumentation. We have performed a detailed theoretical study, using waveguide and free-space modal matching, of the high-Q modes that appear on THz

  14. Structural imaging of nanoscale phonon transport in ferroelectrics excited by metamaterial-enhanced terahertz fields (United States)

    Zhu, Yi; Chen, Frank; Park, Joonkyu; Sasikumar, Kiran; Hu, Bin; Damodaran, Anoop R.; Jung, Il Woong; Highland, Matthew J.; Cai, Zhonghou; Tung, I.-Cheng; Walko, Donald A.; Freeland, John W.; Martin, Lane W.; Sankaranarayanan, Subramanian K. R. S.; Evans, Paul G.; Lindenberg, Aaron M.; Wen, Haidan


    Nanoscale phonon transport is a key process that governs thermal conduction in a wide range of materials and devices. Creating controlled phonon populations by resonant excitation at terahertz (THz) frequencies can drastically change the characteristics of nanoscale thermal transport and allow a direct real-space characterization of phonon mean-free paths. Using metamaterial-enhanced terahertz excitation, we tailored a phononic excitation by selectively populating low-frequency phonons within a nanoscale volume in a ferroelectric BaTi O3 thin film. Real-space time-resolved x-ray diffraction microscopy following THz excitation reveals ballistic phonon transport over a distance of hundreds of nm, two orders of magnitude longer than the averaged phonon mean-free path in BaTi O3 . On longer length scales, diffusive phonon transport dominates the recovery of the transient strain response, largely due to heat conduction into the substrate. The measured real-space phonon transport can be directly compared with the phonon mean-free path as predicted by molecular dynamics modeling. This time-resolved real-space visualization of THz-matter interactions opens up opportunities to engineer and image nanoscale transient structural states with new functionalities.

  15. Detection of foreign bodies in foods using continuous wave terahertz imaging. (United States)

    Lee, Young-Ki; Choi, Sung-Wook; Han, Seong-Tae; Woo, Deog Hyun; Chun, Hyang Sook


    Foreign bodies (FBs) in food are health hazards and quality issues for many food manufacturers and enforcement authorities. In this study, continuous wave (CW) terahertz (THz) imaging at 0.2 THz with an output power of 10 mW was compared with X-ray imaging as techniques for inspection of food for FBs. High-density FBs, i.e., aluminum and granite pieces of various sizes, were embedded in a powdered instant noodle product and detected using THz and X-ray imaging. All aluminum and granite pieces (regular hexahedrons with an edge length of 1 to 5 mm) were visualized by both CW THz and X-ray imaging. THz imaging also detected maggots (length = 8 to 22 mm) and crickets (length = 35 and 50 mm), which were embedded in samples as low density FBs. However, not all sizes of maggot pieces embedded in powdered instant noodle were detected with X-ray imaging, although larger crickets (length = 50 mm and thickness = 10 mm) were detected. These results suggest that CW THz imaging has potential for detecting both high-density and low-density FBs embedded in food.

  16. Contrast in Terahertz Images of Archival Documents—Part I: Influence of the Optical Parameters from the Ink and Support (United States)

    Bardon, Tiphaine; May, Robert K.; Jackson, J. Bianca; Beentjes, Gabriëlle; de Bruin, Gerrit; Taday, Philip F.; Strlič, Matija


    This study aims to objectively inform curators when terahertz time-domain (TD) imaging set in reflection mode is likely to give well-contrasted images of inscriptions in a complex archival document and is a useful non-invasive alternative to current digitisation processes. To this end, the dispersive refractive indices and absorption coefficients from various archival materials are assessed and their influence on contrast in terahertz images from historical documents is explored. Sepia ink and inks produced with bistre or verdigris mixed with a solution of Arabic gum or rabbit skin glue are unlikely to lead to well-contrasted images. However, dispersions of bone black, ivory black, iron gall ink, malachite, lapis lazuli, minium and vermilion are likely to lead to well-contrasted images. Inscriptions written with lamp black, carbon black and graphite give the best imaging results. The characteristic spectral signatures from iron gall ink, minium and vermilion pellets between 5 and 100 cm-1 relate to a ringing effect at late collection times in TD waveforms transmitted through these pellets. The same ringing effect can be probed in waveforms reflected from iron gall, minium and vermilion ink deposits at the surface of a document. Since TD waveforms collected for each scanning pixel can be Fourier-transformed into spectral information, terahertz TD imaging in reflection mode can serve as a hyperspectral imaging tool. However, chemical recognition and mapping of the ink is currently limited by the fact that the morphology of the document influences more the terahertz spectral response of the document than the resonant behaviour of the ink.

  17. Active MMW/Terahertz Security System Based on Bessel Beams


    Igor Minin; Oleg Minin


    The novel concept of the security system based on THz Bessel beams is offered. The system is based on a novel THz diffractive optics for scanning the person (without the application of THz laser) and on a sensitive scheme for the detection of the reflected and scattered THz radiation. The development of enabling technology, namely, sensitive detector arrays and Millimeter wave/THz diffractive optics, will allow building compact, easy-to-use millimeter wave/THz imaging systems without expensiv...

  18. High Sensitivity Terahertz Detection through Large-Area Plasmonic Nano-Antenna Arrays (United States)

    Yardimci, Nezih Tolga; Jarrahi, Mona


    Plasmonic photoconductive antennas have great promise for increasing responsivity and detection sensitivity of conventional photoconductive detectors in time-domain terahertz imaging and spectroscopy systems. However, operation bandwidth of previously demonstrated plasmonic photoconductive antennas has been limited by bandwidth constraints of their antennas and photoconductor parasitics. Here, we present a powerful technique for realizing broadband terahertz detectors through large-area plasmonic photoconductive nano-antenna arrays. A key novelty that makes the presented terahertz detector superior to the state-of-the art is a specific large-area device geometry that offers a strong interaction between the incident terahertz beam and optical pump at the nanoscale, while maintaining a broad operation bandwidth. The large device active area allows robust operation against optical and terahertz beam misalignments. We demonstrate broadband terahertz detection with signal-to-noise ratio levels as high as 107 dB. PMID:28205615

  19. Implementation of an Optical Readout System for High-Sensitivity Terahertz Microelectromechanical Sensor Array (United States)


    thin films and metamaterial structures. This effort culminated in the design and fabrication of novel microelectromechanical systems (MEMS) bi-material...applications, it has been reported that Golay cell micro arrays based on a graphene membrane have been developed with a responsivity of 400 nm/K [26...Grbovic, B. Kearney, and G. Karunasiri, “Microelectromechanical systems bimaterial terahertz sensor with integrated metamaterial absorber,” Opt. Lett

  20. Nanoscale Terahertz Emission Spectroscopy

    DEFF Research Database (Denmark)

    Pedersen, Pernille Klarskov; Kim, Hyewon; Colvin, Vicki L.

    By utilizing plasmonic coupling to an AFM probe, we demonstrate Laser Terahertz Emission Nanoscopy (LTEN) with sub-20 nm resolution. We demonstrate the resolution by imaging a single gold nanorod on an InAs substrate.......By utilizing plasmonic coupling to an AFM probe, we demonstrate Laser Terahertz Emission Nanoscopy (LTEN) with sub-20 nm resolution. We demonstrate the resolution by imaging a single gold nanorod on an InAs substrate....

  1. Terahertz non-destructive imaging of cracks and cracking in structures of cement-based materials (United States)

    Fan, Shujie; Li, Tongchun; Zhou, Jun; Liu, Xiaoqing; Liu, Xiaoming; Qi, Huijun; Mu, Zhiyong


    Cracks and crack propagation in cement-based materials are key factors leading to failure of structures, affecting safety in construction engineering. This work investigated the application of terahertz (THz) non-destructive imaging to inspections on structures of cement-based materials, so as to explore the potential of THz imaging in crack detection. Two kinds of disk specimens made of plain cement mortar and UHMWPE fiber concrete were prepared respectively. A mechanical expansion load device was deployed to generate cracks and control the whole process of cracking. Experimental tests were carried out on cracked specimens by using a commercial THz time domain spectroscopy (THz-TDS) during loading. The results show that crack opening and propagation could be examined by THz clearly and the material factors influence the ability of crack resistance significantly. It was found that the THz imaging of crack initiation and propagation agrees with the practical phenomenon and supplies more information about damage of samples. It is demonstrated that the damage behavior of structures of cement-based materials can be successfully detected by THz imaging.

  2. Seeing Beyond the Painting Surface with Terahertz Time-Domain Imaging (THz-TDI): a signal separation method for extracting images of buried individual layers in paintings

    DEFF Research Database (Denmark)

    Filtenborg, Troels Folke; Skou-Hansen, Jakob; Koch Dandolo, Corinna Ludovica


    In this study, the 18C easel painting The Dying Messalina and her Mother, by Nicolai Abildgaard (Statens Museum for Kunst collection, Copenhagen, Denmark), has been investigated by Terahertz Time-Domain Imaging (THz-TDI) in reflection set-up. Despite the validity of traditional deconvolution...... of the acquired THz image. Interfaces between layers of the painting have been successfully imaged, contributing substantially to the understanding of the structure of the painting....

  3. Time-Domain Terahertz Computed Axial Tomography NDE System (United States)

    Zimdars, David


    NASA has identified the need for advanced non-destructive evaluation (NDE) methods to characterize aging and durability in aircraft materials to improve the safety of the nation's airline fleet. 3D THz tomography can play a major role in detection and characterization of flaws and degradation in aircraft materials, including Kevlar-based composites and Kevlar and Zylon fabric covers for soft-shell fan containment where aging and durability issues are critical. A prototype computed tomography (CT) time-domain (TD) THz imaging system has been used to generate 3D images of several test objects including a TUFI tile (a thermal protection system tile used on the Space Shuttle and possibly the Orion or similar capsules). This TUFI tile had simulated impact damage that was located and the depth of damage determined. The CT motion control gan try was designed and constructed, and then integrated with a T-Ray 4000 control unit and motion controller to create a complete CT TD-THz imaging system prototype. A data collection software script was developed that takes multiple z-axis slices in sequence and saves the data for batch processing. The data collection software was integrated with the ability to batch process the slice data with the CT TD-THz image reconstruction software. The time required to take a single CT slice was decreased from six minutes to approximately one minute by replacing the 320 ps, 100-Hz waveform acquisition system with an 80 ps, 1,000-Hz waveform acquisition system. The TD-THZ computed tomography system was built from pre-existing commercial off-the-shelf subsystems. A CT motion control gantry was constructed from COTS components that can handle larger samples. The motion control gantry allows inspection of sample sizes of up to approximately one cubic foot (.0.03 cubic meters). The system reduced to practice a CT-TDTHz system incorporating a COTS 80- ps/l-kHz waveform scanner. The incorporation of this scanner in the system allows acquisition of 3D

  4. Terahertz Real-Time Imaging Uncooled Arrays Based on Antenna-Coupled Bolometers or FET Developed at CEA-Leti (United States)

    Simoens, François; Meilhan, Jérôme; Nicolas, Jean-Alain


    Sensitive and large-format terahertz focal plane arrays (FPAs) integrated in compact and hand-held cameras that deliver real-time terahertz (THz) imaging are required for many application fields, such as non-destructive testing (NDT), security, quality control of food, and agricultural products industry. Two technologies of uncooled THz arrays that are being studied at CEA-Leti, i.e., bolometer and complementary metal oxide semiconductor (CMOS) field effect transistors (FET), are able to meet these requirements. This paper reminds the followed technological approaches and focuses on the latest modeling and performance analysis. The capabilities of application of these arrays to NDT and security are then demonstrated with experimental tests. In particular, high technological maturity of the THz bolometer camera is illustrated with fast scanning of large field of view of opaque scenes achieved in a complete body scanner prototype.

  5. Three Dimensional Volumetric Terahertz Scanning for Aerospace Non Destructive Evaluation Project (United States)

    National Aeronautics and Space Administration — In this Phase I STTR project, we propose to develop the critical innovations necessary for a high speed three dimesnional terahertz (THz) tomographic imaging system...

  6. Analysis of 3D Prints by X-ray Computed Microtomography and Terahertz Pulsed Imaging. (United States)

    Markl, Daniel; Zeitler, J Axel; Rasch, Cecilie; Michaelsen, Maria Høtoft; Müllertz, Anette; Rantanen, Jukka; Rades, Thomas; Bøtker, Johan


    A 3D printer was used to realise compartmental dosage forms containing multiple active pharmaceutical ingredient (API) formulations. This work demonstrates the microstructural characterisation of 3D printed solid dosage forms using X-ray computed microtomography (XμCT) and terahertz pulsed imaging (TPI). Printing was performed with either polyvinyl alcohol (PVA) or polylactic acid (PLA). The structures were examined by XμCT and TPI. Liquid self-nanoemulsifying drug delivery system (SNEDDS) formulations containing saquinavir and halofantrine were incorporated into the 3D printed compartmentalised structures and in vitro drug release determined. A clear difference in terms of pore structure between PVA and PLA prints was observed by extracting the porosity (5.5% for PVA and 0.2% for PLA prints), pore length and pore volume from the XμCT data. The print resolution and accuracy was characterised by XμCT and TPI on the basis of the computer-aided design (CAD) models of the dosage form (compartmentalised PVA structures were 7.5 ± 0.75% larger than designed; n = 3). The 3D printer can reproduce specific structures very accurately, whereas the 3D prints can deviate from the designed model. The microstructural information extracted by XμCT and TPI will assist to gain a better understanding about the performance of 3D printed dosage forms.

  7. Vis-NIR Hyperspectral and Terahertz Imaging Investigations on a Fresco Painting on "Tavella" by Alessandro Gherardini (United States)

    Doria, A.; Gallerano, G. P.; Giovenale, E.; Casini, A.; Cucci, C.; Picollo, M.; Poggesi, M.; Stefani, L.; Fukunaga, K.; Tamassia, M.


    In this paper, we report on Vis-IR hyperspectral and terahertz imaging investigations carried out on a fresco painting on tavella depicting St. John Baptist, by Alessandro Gherardini (1655-1726). Measurements took place at the Restoration Laboratories of the former "Polo Museale della Toscana," in Florence, in the framework of the Italy-Japan collaborative project THz-ARTE. We show how the hyperspectral data made it possible to determine the state-of-conservation of Gherardini's painting, while reflection imaging measurements performed at 97 GHz provided a qualitative evaluation of the position of defects inside the tavella.

  8. Double-Sided Terahertz Imaging of Multilayered Glass Fiber-Reinforced Polymer

    Directory of Open Access Journals (Sweden)

    Przemyslaw Lopato


    Full Text Available Polymer matrix composites (PMC play important roles in modern industry. Increasing the number of such structures in aerospace, construction, and automotive applications enforces continuous monitoring of their condition. Nondestructive inspection of layered composite materials is much more complicated process than evaluation of homogenous, (mostly metallic structures. Several nondestructive methods are utilized in this case (ultrasonics, shearography, tap testing, acoustic emission, digital radiography, infrared imaging but none of them gives full description of evaluated structures. Thus, further development of NDT techniques should be studied. A pulsed terahertz method seems to be a good candidate for layered PMC inspection. It is based on picosecond electromagnetic pulses interacting with the evaluated structure. Differences of dielectric parameters enables detection of a particular layer in a layered material. In the case of multilayered structures, only layers close to surface can be detected. The response of deeper ones is averaged because of multiple reflections. In this paper a novel inspection procedure with a data processing algorithm is introduced. It is based on a double-sided measurement, acquired signal deconvolution, and data combining. In order to verify the application of the algorithm stress-subjected glass fiber-reinforced polymer (GFRP was evaluated. The obtained results enabled detection and detailed analysis of delaminations introduced by stress treatment and proved the applicability of the proposed algorithm.

  9. Calculation and Study of Graphene Conductivity Based on Terahertz Spectroscopy (United States)

    Feng, Xiaodong; Hu, Min; Zhou, Jun; Liu, Shenggang


    Based on terahertz time-domain spectroscopy system and two-dimensional scanning control system, terahertz transmission and reflection intensity mapping images on a graphene film are obtained, respectively. Then, graphene conductivity mapping images in the frequency range 0.5 to 2.5 THz are acquired according to the calculation formula. The conductivity of graphene at some typical regions is fitted by Drude-Smith formula to quantitatively compare the transmission and reflection measurements. The results show that terahertz reflection spectroscopy has a higher signal-to-noise ratio with less interference of impurities on the back of substrates. The effect of a red laser excitation on the graphene conductivity by terahertz time-domain transmission spectroscopy is also studied. The results show that the graphene conductivity in the excitation region is enhanced while that in the adjacent area is weakened which indicates carriers transport in graphene under laser excitation. This paper can make great contribution to the study on graphene electrical and optical properties in the terahertz regime and help design graphene terahertz devices.

  10. Uncooled Terahertz real-time imaging 2D arrays developed at LETI: present status and perspectives (United States)

    Simoens, François; Meilhan, Jérôme; Dussopt, Laurent; Nicolas, Jean-Alain; Monnier, Nicolas; Sicard, Gilles; Siligaris, Alexandre; Hiberty, Bruno


    As for other imaging sensor markets, whatever is the technology, the commercial spread of terahertz (THz) cameras has to fulfil simultaneously the criteria of high sensitivity and low cost and SWAP (size, weight and power). Monolithic silicon-based 2D sensors integrated in uncooled THz real-time cameras are good candidates to meet these requirements. Over the past decade, LETI has been studying and developing such arrays with two complimentary technological approaches, i.e. antenna-coupled silicon bolometers and CMOS Field Effect Transistors (FET), both being compatible to standard silicon microelectronics processes. LETI has leveraged its know-how in thermal infrared bolometer sensors in developing a proprietary architecture for THz sensing. High technological maturity has been achieved as illustrated by the demonstration of fast scanning of large field of view and the recent birth of a commercial camera. In the FET-based THz field, recent works have been focused on innovative CMOS read-out-integrated circuit designs. The studied architectures take advantage of the large pixel pitch to enhance the flexibility and the sensitivity: an embedded in-pixel configurable signal processing chain dramatically reduces the noise. Video sequences at 100 frames per second using our 31x31 pixels 2D Focal Plane Arrays (FPA) have been achieved. The authors describe the present status of these developments and perspectives of performance evolutions are discussed. Several experimental imaging tests are also presented in order to illustrate the capabilities of these arrays to address industrial applications such as non-destructive testing (NDT), security or quality control of food.

  11. Observation of electromagnetically induced transparency-like transmission in terahertz asymmetric waveguide-cavities systems. (United States)

    Chen, Lin; Gao, Chunmei; Xu, Jiaming; Zang, Xiaofei; Cai, Bin; Zhu, Yiming


    Electromagnetically induced transparency (EIT)-like transmission was demonstrated in terahertz asymmetric parallel plate waveguides with two identical cavities. By shifting the position of the bottom cavity from the symmetric position in the propagation direction, both the phases of the propagating wave at resonances and the coupling strengths between two cavities are changed, resulting in exciting the additional asymmetric resonance and manipulating the detuning of two different resonant frequencies. The transparent peak between two resonances comes from the cancelation of symmetric and asymmetric resonances. We also use the physical picture of excitation of quasi-dark mode to explain this EIT-like transmission, which is similar to the metamaterial systems.

  12. Real-time terahertz wave imaging by nonlinear optical frequency up-conversion in a 4-dimethylamino-N'-methyl-4'-stilbazolium tosylate crystal (United States)

    Fan, Shuzhen; Qi, Feng; Notake, Takashi; Nawata, Kouji; Matsukawa, Takeshi; Takida, Yuma; Minamide, Hiroaki


    Real-time terahertz (THz) wave imaging has wide applications in areas such as security, industry, biology, medicine, pharmacy, and arts. In this letter, we report on real-time room-temperature THz imaging by nonlinear optical frequency up-conversion in organic 4-dimethylamino-N'-methyl-4'-stilbazolium tosylate crystal. The active projection-imaging system consisted of (1) THz wave generation, (2) THz-near-infrared hybrid optics, (3) THz wave up-conversion, and (4) an InGaAs camera working at 60 frames per second. The pumping laser system consisted of two optical parametric oscillators pumped by a nano-second frequency-doubled Nd:YAG laser. THz-wave images of handmade samples at 19.3 THz were taken, and videos of a sample moving and a ruler stuck with a black polyethylene film moving were supplied online to show real-time ability. Thanks to the high speed and high responsivity of this technology, real-time THz imaging with a higher signal-to-noise ratio than a commercially available THz micro-bolometer camera was proven to be feasible. By changing the phase-matching condition, i.e., by changing the wavelength of the pumping laser, we suggest THz imaging with a narrow THz frequency band of interest in a wide range from approximately 2 to 30 THz is possible.

  13. Evaluation of critical process parameters for intra-tablet coating uniformity using terahertz pulsed imaging. (United States)

    Brock, Daniela; Zeitler, J Axel; Funke, Adrian; Knop, Klaus; Kleinebudde, Peter


    The purpose of this study was to evaluate the intra-tablet coating uniformity and the identification of critical process parameters in an active pan coating process using terahertz pulsed imaging (TPI). A design of experiments (DoE) was performed with drum load, drum speed, spray rate, run duration and spray pressure as factors. Different measures of intra-tablet uniformity were investigated: the average thickness on the individual tablet faces, spatial variation in layer thickness over the tablet surface, and the coefficient of variation (CV(intra)). Data analysis revealed that the process parameters in the investigated parameter space had hardly any influence on the difference in layer thickness of the tablet faces and centre band. No increase or decrease in layer thickness--as described in the literature--was found towards the edges of the tablet face. In overwetted process conditions a higher layer thickness at the centre band edges could be observed. Still, the highest variability in coating thickness was found along the circumference of the centre band rather than the height. In general, higher CV(intra) of layer thickness were found on the centre bands in comparison with the tablet faces. The analysis of the DoE model revealed that the run duration had the highest influence on the CV(intra) on the tablet faces. TPI showed high potential in the assessment of intra-tablet uniformity and layer thickness distributions over the whole tablet surface. It was successfully used to identify critical process parameters regarding intra-tablet coating uniformity. Copyright © 2013 Elsevier B.V. All rights reserved.

  14. Contribution of Reflection Terahertz Time Domain-Imaging (THz-TDI) to Imaging Analysis of Artworks

    DEFF Research Database (Denmark)

    Dandolo, Corinna Ludovica Koch; Fukunaga, Kaori; Kohzuma, Y.

    Different kind s of artefacts (easel painting, panel paintings and Asian lacquerwares) have been scanned by THz - TDI and results have been compared with those obtained by others standard imaging techniques (x-ray radiography, cross sectional imaging, technical photography) .......Different kind s of artefacts (easel painting, panel paintings and Asian lacquerwares) have been scanned by THz - TDI and results have been compared with those obtained by others standard imaging techniques (x-ray radiography, cross sectional imaging, technical photography) ....

  15. Towards recognition of energetic materials -Terahertz imaging and sensing at higher frequencies

    NARCIS (Netherlands)

    Huhn, A.K.; Spiegel, W. von; Maagt, P. de; Duvalois. W.; Jagt, O.C. van der; Roskos, H.G.; Haring Bolivar, P.


    The terahertz (THz) frequency range is located between microwave and infrared radiation in the electroma¬gnetic spectrum. It spans from 300 GHz up to 10 THz. The transparency of different materials (e.g. cotton, paper, plastics, etc.) especially at lower THz frequencies opens a great variety of

  16. Terahertz semiconductor-heterostructure laser. (United States)

    Köhler, Rüdeger; Tredicucci, Alessandro; Beltram, Fabio; Beere, Harvey E; Linfield, Edmund H; Davies, A Giles; Ritchie, David A; Iotti, Rita C; Rossi, Fausto


    Semiconductor devices have become indispensable for generating electromagnetic radiation in everyday applications. Visible and infrared diode lasers are at the core of information technology, and at the other end of the spectrum, microwave and radio-frequency emitters enable wireless communications. But the terahertz region (1-10 THz; 1 THz = 10(12) Hz) between these ranges has remained largely underdeveloped, despite the identification of various possible applications--for example, chemical detection, astronomy and medical imaging. Progress in this area has been hampered by the lack of compact, low-consumption, solid-state terahertz sources. Here we report a monolithic terahertz injection laser that is based on interminiband transitions in the conduction band of a semiconductor (GaAs/AlGaAs) heterostructure. The prototype demonstrated emits a single mode at 4.4 THz, and already shows high output powers of more than 2 mW with low threshold current densities of about a few hundred A cm(-2) up to 50 K. These results are very promising for extending the present laser concept to continuous-wave and high-temperature operation, which would lead to implementation in practical photonic systems.

  17. Optical Readout System for Bi-Material Terahertz Sensors (United States)


    progressive scan, which allows all pixels’ signals to be output independently in non- interlace format in 15 fps. All pixels’ signals within the 3, p. 034708, 2011. [10] D. Grbovic, “Imaging by Detection of Infrared Photons Using Arrays of Uncooled Micromechanical Detectors,” PhD...Micromechanical uncooled photon detectors,” in Proceedings of SPIE, San Jose, CA, USA, 2000, pp. 80–93. [31] Yang Zhao et al., “Optomechanical uncooled infrared

  18. Non-invasive Florentine Renaissance Panel Painting Replica Structures Investigation by Using Terahertz Time-Domain Imaging (THz-TDI) Technique

    DEFF Research Database (Denmark)

    Dandolo, Corinna Ludovica Koch; Picollo, Marcello; Cucci, Costanza


    The potentials of the Terahertz Time-Domain Imaging (THz-TDI) technique for a non-invasive inspection of panel paintings have been considered in detail. The THz-TD data acquired on a replica of a panel painting made in imitation of Italian Renaissance panel paintings were processed in order to pr...

  19. An automated test system for terahertz receiver characterization (United States)

    Kuenzi, Linda C.; Groppi, Christopher E.; Wheeler, Caleb H.; Mani, Hamdi


    An automated test system was developed to characterize detectors for the Kilopixel Array Pathfinder Project (KAPPa), a 16-pixel 2D integrated heterodyne focal plane array. Although primarily designed for KAPPa, the system can be used with other instruments to automate tests that might be tedious and time-consuming by hand. Mechanical components include an adjustable structure of aluminum t-slot framing that supports a rotating chopper. Driven by a stepper motor, the wheel alternates between blackbodies at room temperature and 77 K. The cold load consists of absorbing material submerged in liquid nitrogen in an open Styrofoam cooler. Python scripts control the mechanical system, interface with receiver components, and process data. Test system operation was verified by sweeping the local oscillator frequency with a Virginia Diodes room temperature receiver. The system was then integrated with the KAPPa receiver to allow complete and automated testing of all array pixels with minimal user intervention.

  20. Collaborative Initiative in Biomedical Imaging to Study Complex Diseases

    Energy Technology Data Exchange (ETDEWEB)

    Lin, Weili [The University of North Carolina at Chapel Hill; Fiddy, Michael A. [The University of North Carolina at Charlotte


    The work reported addressed these topics: Fluorescence imaging; Optical coherence tomography; X-ray interferometer/phase imaging system; Quantitative imaging from scattered fields, Terahertz imaging and spectroscopy; and Multiphoton and Raman microscopy.

  1. Millimeter-wave and Terahertz Reconfigurable Radio-over-Fiber Systems

    DEFF Research Database (Denmark)

    Vegas Olmos, Juan José

    on photonic technologies enable to generate, transport and radiate in a straight forward manner microwave and millimeter wave signals. Although electronic technologies are able to sustain an increase in frequency from a technology point of view, with current developments hitting the Terahertz regime...... when deploying fiber is not an option. Radio-over-Fiber (RoF) technologies have evolved from a blue sky academic topic in the 90s to a main driver within the current quest for the 5th generation mobile systems (5G). A twist in RoF technologies is that it has found along the way niches in areas non...... purely related to communication technologies (ICT) applications: distribution of highly pure clock signals for radio telescopes, photonic-based coherent radar and fiber optic sensing. It is however in the communication arena where RoF seems to be able to provide a technological edge; RoF techniques based...

  2. Polarization insensitive terahertz metamaterial absorber. (United States)

    Grant, J; Ma, Y; Saha, S; Lok, L B; Khalid, A; Cumming, D R S


    We present the simulation, implementation, and measurement of a polarization insensitive resonant metamaterial absorber in the terahertz region. The device consists of a metal/dielectric-spacer/metal structure allowing us to maximize absorption by varying the dielectric material and thickness and, hence, the effective electrical permittivity and magnetic permeability. Experimental absorption of 77% and 65% at 2.12 THz (in the operating frequency range of terahertz quantum cascade lasers) is observed for a spacer of polyimide or silicon dioxide respectively. These metamaterials are promising candidates as absorbing elements for thermally based terahertz imaging.

  3. Terahertz Techniques

    CERN Document Server

    Bründermann, Erik; Kimmitt, Maurice FitzGerald


    Research and development in the terahertz portion of the electromagnetic spectrum has expanded very rapidly during the past fifteen years due to major advances in sources, detectors and instrumentation. Many scientists and engineers are entering the field and this volume offers a comprehensive and integrated treatment of all aspects of terahertz technology. The three authors, who have been active researchers in this region over a number of years, have designed Terahertz Techniques to be both a general introduction to the subject and a definitive reference resource for all those involved in this exciting research area.

  4. Enhanced Terahertz Imaging of Small Forced Delamination in Woven Glass Fibre-reinforced Composites with Wavelet De-noising (United States)

    Dong, Junliang; Locquet, Alexandre; Citrin, D. S.


    Terahertz (THz) reflection imaging is applied to characterize a woven glass fibre-reinforced composite laminate with a small region of forced delamination. The forced delamination is created by inserting a disk of 25- μ m-thick Upilex film, which is below the THz axial resolution, resulting in one featured echo with small amplitude in the reflected THz pulses. Low-amplitude components of the temporal signal due to ambient water vapor produce features of comparable amplitude with features associated with the THz pulse reflected off the interfaces of the delamination and suppress the contrast of THz C- and B-scans. Wavelet shrinkage de-noising is performed to remove water-vapor features, leading to enhanced THz C- and B-scans to locate the delamination in three dimensions with high contrast.

  5. FDTD-based quantitative analysis of terahertz wave detection for multilayered structures. (United States)

    Tu, Wanli; Zhong, Shuncong; Shen, Yaochun; Zhou, Qing; Yao, Ligang


    Experimental investigations have shown that terahertz pulsed imaging (TPI) is able to quantitatively characterize a range of multilayered media (e.g., biological issues, pharmaceutical tablet coatings, layered polymer composites, etc.). Advanced modeling of the interaction of terahertz radiation with a multilayered medium is required to enable the wide application of terahertz technology in a number of emerging fields, including nondestructive testing. Indeed, there have already been many theoretical analyses performed on the propagation of terahertz radiation in various multilayered media. However, to date, most of these studies used 1D or 2D models, and the dispersive nature of the dielectric layers was not considered or was simplified. In the present work, the theoretical framework of using terahertz waves for the quantitative characterization of multilayered media was established. A 3D model based on the finite difference time domain (FDTD) method is proposed. A batch of pharmaceutical tablets with a single coating layer of different coating thicknesses and different refractive indices was modeled. The reflected terahertz wave from such a sample was computed using the FDTD method, assuming that the incident terahertz wave is broadband, covering a frequency range up to 3.5 THz. The simulated results for all of the pharmaceutical-coated tablets considered were found to be in good agreement with the experimental results obtained using a commercial TPI system. In addition, we studied a three-layered medium to mimic the occurrence of defects in the sample.

  6. Terahertz imaging of Landau levels in HgTe-based topological insulators

    Energy Technology Data Exchange (ETDEWEB)

    Kadykov, Aleksandr M.; Krishtopenko, Sergey S. [Laboratoire Charles Coulomb (L2C), UMR 5221 CNRS–Université de Montpellier, Montpellier (France); Institute for Physics of Microstructures, Russian Academy of Sciences, GSP-105, 603950 Nizhny Novgorod (Russian Federation); Torres, Jeremie [Institut d' Electronique et des Systèmes (IES), UMR 5214 CNRS–Université de Montpellier, Montpellier (France); Consejo, Christophe; Ruffenach, Sandra; Marcinkiewicz, Michal; But, Dmytro; Teppe, Frederic, E-mail: [Laboratoire Charles Coulomb (L2C), UMR 5221 CNRS–Université de Montpellier, Montpellier (France); Knap, Wojciech [Laboratoire Charles Coulomb (L2C), UMR 5221 CNRS–Université de Montpellier, Montpellier (France); Institute of High Pressure Institute Physics, Polish Academy of Sciences, 01-447 Warsaw (Poland); Morozov, Sergey V.; Gavrilenko, Vladimir I. [Institute for Physics of Microstructures, Russian Academy of Sciences, GSP-105, 603950 Nizhny Novgorod (Russian Federation); Lobachevsky State University of Nizhny Novgorod, 603950 Nizhny Novgorod (Russian Federation); Mikhailov, Nikolai N. [Institute of Semiconductor Physics, Siberian Branch, Russian Academy of Sciences, pr. Akademika Lavrent' eva 13, 630090 Novosibirsk (Russian Federation); Novosibirsk State University, 630090 Novosibirsk (Russian Federation); Dvoretsky, Sergey A. [Institute of Semiconductor Physics, Siberian Branch, Russian Academy of Sciences, pr. Akademika Lavrent' eva 13, 630090 Novosibirsk (Russian Federation)


    We report on sub-terahertz photoconductivity under the magnetic field of a two dimensional topological insulator based on HgTe quantum wells. We perform a detailed visualization of Landau levels by means of photoconductivity measured at different gate voltages. This technique allows one to determine a critical magnetic field, corresponding to topological phase transition from inverted to normal band structure, even in almost gapless samples. The comparison with realistic calculations of Landau levels reveals a smaller role of bulk inversion asymmetry in HgTe quantum wells than it was assumed previously.

  7. Continuous-wave terahertz reflective off-axis digital holography (United States)

    Wan, Min; Wang, Dayong; Rong, Lu; Wang, Yunxin; Huang, Haochong; Li, Bin


    Terahertz (THz) continuous-wave digital holography is an advanced interference imaging technique that can reconstruct quantitative distributions of amplitude and phase of the sample in real time with high resolution. In this paper, a reflective off-axis holographic system is presented. A Gaussian fitting method is applied to enhance the hologram contrast and Laplacian of Gaussian filter is used to obtain the reconstructed distance automatically. Furthermore, spectrum filtering method and angular spectrum algorithm are used to obtain the complex amplitude of the one-yuan chinese metal coin. The results confirm the prospective application of terahertz digital holography in the surface morphology for reflective samples.

  8. Review of terahertz technology development at INO (United States)

    Dufour, Denis; Marchese, Linda; Terroux, Marc; Oulachgar, Hassane; Généreux, Francis; Doucet, Michel; Mercier, Luc; Tremblay, Bruno; Alain, Christine; Beaupré, Patrick; Blanchard, Nathalie; Bolduc, Martin; Chevalier, Claude; D'Amato, Dominic; Desroches, Yan; Duchesne, François; Gagnon, Lucie; Ilias, Samir; Jerominek, Hubert; Lagacé, François; Lambert, Julie; Lamontagne, Frédéric; Le Noc, Loïc; Martel, Anne; Pancrati, Ovidiu; Paultre, Jacques-Edmond; Pope, Tim; Provençal, Francis; Topart, Patrice; Vachon, Carl; Verreault, Sonia; Bergeron, Alain


    Over the past decade, INO has leveraged its expertise in the development of uncooled microbolometer detectors for infrared imaging to produce terahertz (THz) imaging systems. By modifying its microbolometer-based focal plane arrays to enhance absorption in the THz bands and by developing custom THz imaging lenses, INO has developed a leading-edge THz imaging system, the IRXCAM-THz-384 camera, capable of exploring novel applications in the emerging field of terahertz imaging and sensing. Using appropriate THz sources, results show that the IRXCAM-THz-384 camera is able to image a variety of concealed objects of interest for applications such as non-destructive testing and weapons detections. By using a longer wavelength (94 GHz) source, it is also capable of sensing the signatures of various objects hidden behind a drywall panel. This article, written as a review of THz research at INO over the past decade, describes the technical components that form the IRXCAM-THz-384 camera and the experimental setup used for active THz imaging. Image results for concealed weapons detection experiments, an exploration of wavelength choice on image quality, and the detection of hidden objects behind drywall are also presented.

  9. History of Mexican Easel Paintings from an Altarpiece Revealed by Non-invasive Terahertz Time-Domain Imaging (United States)

    Gomez-Sepulveda, A. M.; Hernandez-Serrano, A. I.; Radpour, R.; Koch-Dandolo, C. L.; Rojas-Landeros, S. C.; Ascencio-Rojas, L. F.; Zarate, Alvaro; Hernandez, Gerardo; Gonzalez-Tirado, R. C.; Insaurralde-Caballero, M.; Castro-Camus, E.


    Four easel paintings attributed to Hermenegildo Bustos ( Purísima del Rincón, Guanajuato, Mexico), one of the most renowned painters of the late nineteenth and early twentieth century Mexican art, have been investigated by means of terahertz time-domain imaging (THz-TDI) and standard imaging techniques, such as near-IR reflectography and X-ray radiography. The archival sources and the recent studies on the paintings suggest that the artworks were created in the eighteenth century and underwent several modifications since then until the intervention of Bustos who authored the currently visible depictions. By combining the records of the paintings obtained by imaging with the different methodologies, aspects of the previous depictions and further details on the paintings' history have been revealed, with THz-TDI playing a key role in attributing a chronological evolution of the images. The paintings of Purísima are the first THz-TDI-scanned paintings belonging to the Mexican cultural heritage.

  10. Terahertz scanning probe microscope

    NARCIS (Netherlands)

    Klapwijk, T.M.


    The invention provides aterahertz scanning probe microscope setup comprising (i) a terahertz radiation source configured to generate terahertz radiation; (ii) a terahertz lens configured to receive at least part of the terahertz radiation from the terahertz radiation source; (iii) a cantilever unit

  11. Enantiomeric switching of chiral metamaterial for terahertz polarization modulation employing vertically deformable MEMS spirals (United States)

    Kan, Tetsuo; Isozaki, Akihiro; Kanda, Natsuki; Nemoto, Natsuki; Konishi, Kuniaki; Takahashi, Hidetoshi; Kuwata-Gonokami, Makoto; Matsumoto, Kiyoshi; Shimoyama, Isao


    Active modulation of the polarization states of terahertz light is indispensable for polarization-sensitive spectroscopy, having important applications such as non-contact Hall measurements, vibrational circular dichroism measurements and anisotropy imaging. In the terahertz region, the lack of a polarization modulator similar to a photoelastic modulator in the visible range hampers expansion of such spectroscopy. A terahertz chiral metamaterial has a huge optical activity unavailable in nature; nevertheless, its modulation is still challenging. Here we demonstrate a handedness-switchable chiral metamaterial for polarization modulation employing vertically deformable Micro Electro Mechanical Systems. Vertical deformation of a planar spiral by a pneumatic force creates a three-dimensional spiral. Enantiomeric switching is realized by selecting the deformation direction, where the polarity of the optical activity is altered while maintaining the spectral shape. A polarization rotation as high as 28° is experimentally observed, thus providing a practical and compact polarization modulator for the terahertz range. PMID:26423346

  12. Frequency selective terahertz retroreflectors (United States)

    Williams, Richard James

    The use of novel optical structures operating at terahertz frequencies in industrial and military applications continues to grow. Some of these novel structures include gratings, frequency selective surfaces, metamaterials and metasurfaces, and retroreflectors. A retroreflector is a device that exhibits enhanced backscatter by concentrating the reflected wave in the direction of the source. Retroreflectors have applications in a variety of diverse fields such as aviation, radar systems, antenna technology, communications, navigation, passive identification, and metrology due to their large acceptance angles and frequency bandwidth. This thesis describes the design, fabrication, and characterization of a retroreflector designed for terahertz frequencies and the incorporation of a frequency selective surface in order to endow the retroreflector with narrow-band frequency performance. The radar cross section of several spherical lens reflectors operating at terahertz frequencies was investigated. Spherical lens reflectors with diameters ranging from 2 mm to 8 mm were fabricated from fused silica ball lenses and their radar cross section was measured at 100 GHz, 160 GHz, and 350 GHz. Crossed-dipole frequency selective surfaces exhibiting band-pass characteristics at 350 GHz fabricated from 12 um-thick Nickel screens were applied to the apertures of the spherical lens reflectors. The radar cross section of the frequency selective retroreflectors was measured at 160 GHz and 350 GHz to demonstrate proof-of-concept of narrow-band terahertz performance.

  13. Multi-spectral materials: hybridisation of optical plasmonic filters, a mid infrared metamaterial absorber and a terahertz metamaterial absorber. (United States)

    Grant, James; McCrindle, Iain J H; Cumming, David R S


    Multi-spectral imaging systems typically require the cumbersome integration of disparate filtering materials and detectors in order to operate simultaneously in multiple spectral regions. Each distinct waveband must be detected at different spatial locations on a single chip or by separate chips optimised for each band. Here, we report on a single component that optically multiplexes visible, Mid Infrared (4.5 μm) and Terahertz (126 μm) radiation thereby maximising the spectral information density. We hybridise plasmonic and metamaterial structures to form a device capable of simultaneously filtering 15 visible wavelengths and absorbing Mid Infrared and Terahertz. Our synthetic multi-spectral component could be integrated with silicon complementary metal-oxide semiconductor technology where Si photodiodes are available to detect the visible radiation and micro-bolometers available to detect the Infrared/Terahertz and render an inexpensive, mass-producible camera capable of forming coaxial visible, Infrared and Terahertz images.

  14. THz imaging techniques for nondestructive inspections (United States)

    Kawase, Kodo; Shibuya, Takayuki; Hayashi, Shin'ichiro; Suizu, Koji


    We have suggested a wide range of real-life applications using novel terahertz imaging techniques. A high-resolution terahertz tomography has been demonstrated by ultra short terahertz pulses using optical fiber and a nonlinear organic crystal. We also describe a nondestructive inspection system that can monitor the soot distribution in a ceramic filter using millimeter-to-terahertz wave computed tomography. Further, we report on the thickness measurement of very thin films using high-sensitivity metal mesh filter. These techniques are directly applicable to the nondestructive testing in industries.

  15. Wall Painting Investigation by Means of Non-invasive Terahertz Time-Domain Imaging (THz-TDI): Inspection of Subsurface Structures Buried in Historical Plasters (United States)

    Dandolo, Corinna Ludovica Koch; Jepsen, Peter Uhd


    Characterization of subsurface features of wall paintings is important in conservation and technical art history as well as in building archaeology and architecture fields. In this study, an area of the apsidal wall painting of Nebbelunde Church (Rødby, Denmark) has been investigated by means of terahertz time-domain imaging (THz-TDI). Subsurface structures have been detected at different depths inside the lime-based plaster of the wall painting until approximately 1 cm from the surface. The surface morphology of the buried structures has been 3D imaged in detail, providing a substantial contribution in their characterization.

  16. Wall Painting Investigation by Means of Non-invasive Terahertz Time-Domain Imaging (THz-TDI): Inspection of Subsurface Structures Buried in Historical Plasters

    DEFF Research Database (Denmark)

    Dandolo, Corinna Ludovica Koch; Jepsen, Peter Uhd


    Characterization of subsurface features of wall paintings is important in conservation and technical art history as well as in building archaeology and architecture fields. In this study, an area of the apsidal wall painting of Nebbelunde Church (Rødby, Denmark) has been investigated by means...... of terahertz time-domain imaging (THz-TDI). Subsurface structures have been detected at different depths inside the lime-based plaster of the wall painting until approximately 1 cm from the surface. The surface morphology of the buried structures has been 3D imaged in detail, providing a substantial...

  17. Ultrahigh polarimetric image contrast enhancement for skin cancer diagnosis using InN plasmonic nanoparticles in the terahertz range. (United States)

    Ney, Michael; Abdulhalim, Ibrahim


    Mueller matrix imaging sensitivity, to delicate water content changes in tissue associated with early stages of skin cancer, is demonstrated by numerical modeling to be enhanced by localized surface plasmon resonance (LSPR) effects at the terahertz (THz) range when InN nanoparticles (NPs) coated with Parylene-C are introduced into the skin. A skin tissue model tailored for THz wavelengths is established for a Monte Carlo simulation of polarized light propagation and scattering, and a comparative study based on simulated Mueller matrices is presented considering different NPs’ parameters and insertion into the skin methods. The insertion of NPs presenting LSPR in the THz is demonstrated to enable the application of polarization-based sample characterization techniques adopted from the scattering dominated visible wavelengths domain for the, otherwise, relatively low scattering THz domain, where such approach is irrelevant without the NPs. Through these Mueller polarimetry techniques, the detection of water content variations in the tissue is made possible and with high sensitivity. This study yields a limit of detection down to 0.0018% for relative changes in the water content based on linear degree of polarization--an improvement of an order of magnitude relative to the limit of detection without NPs calculated in a previous ellipsometric study.

  18. Evaluation of critical process parameters for inter-tablet coating uniformity of active-coated GITS using Terahertz Pulsed Imaging. (United States)

    Brock, Daniela; Zeitler, J Axel; Funke, Adrian; Knop, Klaus; Kleinebudde, Peter


    The aim of this study was the evaluation of critical process parameters (CPP) for inter-tablet coating uniformity in an active pan coating process using nondestructive Terahertz Pulsed Imaging (TPI). Coating uniformity was assessed by calculating the coefficient of variation (CV) of coating thickness measured by TPI, and the CV of API content measured by high performance liquid chromatography (HPLC). A design of experiments (DoE) was performed at pilot scale with drum load, drum speed, spray rate, run duration and spray pressure as factors. Good agreement in the CV of both analytical techniques was shown. The DoE models both revealed the same CPP: a low drum load, high drum speed, low spray rate and high run duration were beneficial for coating uniformity. The spray pressure was only significant in one of the DoE models. It was further shown that the negative impact of a high drum load on the CV cannot only be compensated by high drum speed, but also be compensated by a low spray rate and long run duration. It was demonstrated that TPI is a feasible tool for the measurement of inter-tablet coating uniformity and for the evaluation of CPP in an active pan coating process. Copyright © 2014 Elsevier B.V. All rights reserved.

  19. Terahertz computed tomography in three-dimensional using a pyroelectric array detector (United States)

    Li, Bin; Wang, Dayong; Zhou, Xun; Rong, Lu; Huang, Haochong; Wan, Min; Wang, Yunxin


    Terahertz frequency range spans from 0.1 to 10 THz. Terahertz radiation can penetrate nonpolar materials and nonmetallic materials, such as plastics, wood, and clothes. Then the feature makes the terahertz imaging have important research value. Terahertz computed tomography makes use of the penetrability of terahertz radiation and obtains three-dimensional object projection data. In the paper, continuous-wave terahertz computed tomography with a pyroelectric array detectoris presented. Compared with scanning terahertz computed tomography, a pyroelectric array detector can obtain a large number of projection data in a short time, as the acquisition mode of the array pyroelectric detector omit the projection process on the vertical and horizontal direction. With the two-dimensional cross-sectional images of the object are obtained by the filtered back projection algorithm. The two side distance of the straw wall account for 80 pixels, so it multiplied by the pixel size is equal to the diameter of the straw about 6.4 mm. Compared with the actual diameter of the straw, the relative error is 6%. In order to reconstruct the three-dimensional internal structure image of the straw, the y direction range from 70 to 150 are selected on the array pyroelectric detector and are reconstructed by the filtered back projection algorithm. As the pixel size is 80 μm, the height of three-dimensional internal structure image of the straw is 6.48 mm. The presented system can rapidly reconstruct the three-dimensional object by using a pyroelectric array detector and explores the feasibility of on non-destructive evaluation and security testing.

  20. Polarization-stable dual-color DFB fibre laser system for CW terahertz generation

    DEFF Research Database (Denmark)

    Eichhorn, Finn; Petersen, Jens Engholm; Jepsen, Peter Uhd

    The terahertz, or THz, frequency range represents a gap in technology as well as knowledge in the electromagnetic spectrum. The THz spectral range is here loosely defined as frequencies between 100 GHz and 10 THz. Electromagnetic waves at THz frequencies interact strongly with metals, ceramics...

  1. Precise Ab-initio prediction of terahertz vibrational modes in crystalline systems

    DEFF Research Database (Denmark)

    Jepsen, Peter Uhd; Clark, Stewart J.


    We use a combination of experimental THz time-domain spectroscopy and ab-initio density functional perturbative theory to accurately predict the terahertz vibrational spectrum of molecules in the crystalline phase. Our calculations show that distinct vibrational modes found in solid-state materials...

  2. Terahertz Solitons in Biomolecular Systems and their Excitation by External Electromagnetic Field

    Directory of Open Access Journals (Sweden)

    Bugay А.N.


    Full Text Available Nonlinear dynamics of charge and acoustic excitations in cellular microtubules is considered. Different types of nonlinear solitary waves were studied taking account for dissipation. The mechanism of electro-acoustic pulse excitation by external electromagnetic field of terahertz frequency is recognized.

  3. Medical imaging systems (United States)

    Frangioni, John V


    A medical imaging system provides simultaneous rendering of visible light and diagnostic or functional images. The system may be portable, and may include adapters for connecting various light sources and cameras in open surgical environments or laparascopic or endoscopic environments. A user interface provides control over the functionality of the integrated imaging system. In one embodiment, the system provides a tool for surgical pathology.

  4. Narrowband Metamaterial Absorber for Terahertz Secure Labeling (United States)

    Nasr, Magued; Richard, Jonathan T.; Skirlo, Scott A.; Heimbeck, Martin S.; Joannopoulos, John D.; Soljacic, Marin; Everitt, Henry O.; Domash, Lawrence


    Flexible metamaterial films, fabricated by photolithography on a thin copper-backed polyimide substrate, are used to mark or barcode objects securely. The films are characterized by continuous-wave terahertz spectroscopic ellipsometry and visualized by a scanning confocal imager coupled to a vector network analyzer that constructed a terahertz spectral hypercube. These films exhibit a strong, narrowband, polarization- and angle-insensitive absorption at wavelengths near 1 mm. Consequently, the films are nearly indistinguishable at visible or infrared wavelengths and may be easily observed by terahertz imaging only at the resonance frequency of the film.

  5. Optically Modulated Multiband Terahertz Perfect Absorber

    DEFF Research Database (Denmark)

    Seren, Huseyin R.; Keiser, George R.; Cao, Lingyue


    response of resonant metamaterials continues to be a challengingendeavor. Resonant perfect absorbers have flourished as one of the mostpromising metamaterial devices with applications ranging from power har-vesting to terahertz imaging. Here, an optically modulated resonant perfectabsorber is presented...

  6. Resonant Excitation of Terahertz Surface Plasmons in Subwavelength Metal Holes

    Directory of Open Access Journals (Sweden)

    Weili Zhang


    Full Text Available We present a review of experimental studies of resonant excitation of terahertz surface plasmons in two-dimensional arrays of subwavelength metal holes. Resonant transmission efficiency higher than unity was recently achieved when normalized to the area occupied by the holes. The effects of hole shape, hole dimensions, dielectric function of metals, polarization dependence, and array film thickness on resonant terahertz transmission in metal arrays were investigated by the state-of-the-art terahertz time-domain spectroscopy. In particular, extraordinary terahertz transmission was demonstrated in arrays of subwavelength holes made even from Pb, a generally poor metal, and having thickness of only one-third of skin depth. Terahertz surface plasmons have potential applications in terahertz imaging, biosensing, interconnects, and development of integrated plasmonic components for terahertz generation and detection.

  7. Sparsity based terahertz reflective off-axis digital holography (United States)

    Wan, Min; Muniraj, Inbarasan; Malallah, Ra'ed; Zhao, Liang; Ryle, James P.; Rong, Lu; Healy, John J.; Wang, Dayong; Sheridan, John T.


    Terahertz radiation lies between the microwave and infrared regions in the electromagnetic spectrum. Emitted frequencies range from 0.1 to 10 THz with corresponding wavelengths ranging from 30 μm to 3 mm. In this paper, a continuous-wave Terahertz off-axis digital holographic system is described. A Gaussian fitting method and image normalisation techniques were employed on the recorded hologram to improve the image resolution. A synthesised contrast enhanced hologram is then digitally constructed. Numerical reconstruction is achieved using the angular spectrum method of the filtered off-axis hologram. A sparsity based compression technique is introduced before numerical data reconstruction in order to reduce the dataset required for hologram reconstruction. Results prove that a tiny amount of sparse dataset is sufficient in order to reconstruct the hologram with good image quality.

  8. Non-invasive Florentine Renaissance Panel Painting Replica Structures Investigation by Using Terahertz Time-Domain Imaging (THz-TDI) Technique (United States)

    Koch Dandolo, Corinna L.; Picollo, Marcello; Cucci, Costanza; Jepsen, Peter Uhd


    The potentials of the Terahertz Time-Domain Imaging (THz-TDI) technique for a non-invasive inspection of panel paintings have been considered in detail. The THz-TD data acquired on a replica of a panel painting made in imitation of Italian Renaissance panel paintings were processed in order to provide insights as to the limits and potentials of the technique in detecting different kinds of underdrawings and paint layers. Constituent layers, construction techniques, and anomalies were identified and localized by interpreting the extracted THz dielectric stratigraphy.

  9. Terahertz near-field microspectroscopy

    NARCIS (Netherlands)

    Knab, J.R.; Adam, A.J.L.; Chakkittakandy, R.; Planken, P.C.M.


    Using near-field, terahertz time-domain spectroscopy (THz-TDS), we investigate how the addition of a dielectric material into a subwavelength-diameter, cylindrical waveguide affects its transmission properties. The THz electric near-field is imaged with deep subwavelength resolution as it emerges

  10. THz wave generation and imaging for industrial applications (United States)

    Kawase, K.; Shibuya, T.; Suizu, K.; Hayashi, S.


    We have suggested a wide range of real-life applications using novel terahertz imaging techniques. A high-resolution terahertz tomography was demonstrated by ultra short terahertz pulses using optical fiber and a nonlinear organic crystal. We also describe a non-destructive inspection system that can monitor the soot distribution in the ceramic filter using millimeter-to-terahertz wave computed tomography. Further we report on the thickness measurement of very thin films using high-sensitivity metal mesh filter. These techniques are directly applicable to the non-destructive testing in industries.

  11. Precise real-time polarization measurement of terahertz electromagnetic waves by a spinning electro-optic sensor. (United States)

    Yasumatsu, Naoya; Watanabe, Shinichi


    We propose and develop a method to quickly and precisely determine the polarization direction of coherent terahertz electromagnetic waves generated by femtosecond laser pulses. The measurement system consists of a conventional terahertz time-domain spectroscopy system with the electro-optic (EO) sampling method, but we add a new functionality in the EO crystal which is continuously rotating with the angular frequency ω. We find a simple yet useful formulation of the EO signal as a function of the crystal orientation, which enables a lock-in-like detection of both the electric-field amplitude and the absolute polarization direction of the terahertz waves with respect to the probe laser pulse polarization direction at the same time. The single measurement finishes around two periods of the crystal rotations (∼21 ms), and we experimentally prove that the accuracy of the polarization measurement does not suffer from the long-term amplitude fluctuation of the terahertz pulses. Distribution of the measured polarization directions by repeating the measurements is excellently fitted by a gaussian distribution function with a standard deviation of σ = 0.56°. The developed technique is useful for the fast direct determination of the polarization state of the terahertz electromagnetic waves for polarization imaging applications as well as the precise terahertz Faraday or Kerr rotation spectroscopy.

  12. Practical microstructured and plasmonic terahertz waveguides (United States)

    Markov, Andrey

    The terahertz frequency range, with frequencies lying between 100 GHz and 10 THz, has strong potential for various technological and scientific applications such as sensing, imaging, communications, and spectroscopy. Most terahertz (THz) sources are immobile and THz systems use free-space propagation in dry air where losses are minimal. Designing efficient THz waveguides for flexible delivery of broadband THz radiation is an important step towards practical applications of terahertz techniques. THz waveguides can be very useful on the system integration level when used for connection of the diverse THz point devices, such as sources, filters, sensor cells, detectors, etc. The most straightforward application of waveguides is to deliver electromagnetic waves from the source to the point of detection. Cumbersome free-space optics can be replaced by waveguides operating in the THz range, which could lead to the development of compact THz time domain spectroscopy systems. Other promising applications of THz waveguides are in sensing and imaging. THz waveguides have also been shown to operate in subwavelength regimes, offering mode confinement in waveguide structures with a size smaller than the diffraction limit, and thus, surpassing the resolution of free-space THz imaging systems. In order to design efficient terahertz waveguides, the frequency dependent loss and dispersion of the waveguide must be minimized. A possible solution would be to increase the fraction of mode power propagating through air. In this thesis, the usage of planar porous air/dielectric waveguides and metal wire/dielectric hybrid terahertz fibers will be discussed. First, I present a novel design of a planar porous low-loss waveguide, describe its fabrication, and characterize it in view of its potential applications as a low-loss waveguide and sensor in the THz spectral range. The waveguide structure features a periodic sequence of layers of thin (25-50 mum) polyethylene film that are separated

  13. Inspection of Asian Lacquer Substructures by Terahertz Time-Domain Imaging (THz-TDI) (United States)

    Dandolo, Corinna Ludovica Koch; Fukunaga, Kaori; Kohzuma, Yoshei; Kiriyama, Kyoko; Matsuda, Kazutaka; Jepsen, Peter Uhd


    Lacquering is considered one of the most representative Asian artistic techniques. While the decorative part of lacquerwares is the lacquer itself, their substructures serve as the backbone of the object itself. Very little is known about these hidden substructures. Since lacquerwares are mostly composed of organic materials, such as urushi, wood, carbon black, and fabrics which are very X-ray transparent, standard X-ray radiography has some problems in achieving clear X-ray radiographic images. Therefore, we wanted to contribute to the understanding of the lacquer manufacturing technique by inspecting the substructures of Asian lacquerwares by means of THz time-domain imaging (THz-TDI). Three different kinds of Asian lacquerwares were examined by THz-TDI, and the outcomes have been compared with those obtained by standard X-radiography. THz-TDI provides unique information on lacquerwares substructures, aiding in the comprehension of the manufacturing technology yielding to these precious artefacts.

  14. Inspection of Asian Lacquer Substructures by Terahertz Time-Domain Imaging (THz-TDI)

    DEFF Research Database (Denmark)

    Dandolo, Corinna Ludovica Koch; Fukunaga, Kaori; Kohzuma, Yoshei


    Lacquering is considered one of the most representative Asian artistic techniques. While the decorative part of lacquerwares is the lacquer itself, their substructures serve as the backbone of the object itself. Very little is known about these hidden substructures. Since lacquerwares are mostly...... by inspecting the substructures of Asian lacquerwares by means of THz time-domain imaging (THz-TDI). Three different kinds of Asian lacquerwares were examined by THz-TDI, and the outcomes have been compared with those obtained by standard X-radiography. THz-TDI provides unique information on lacquerwares...

  15. Medical imaging systems

    Energy Technology Data Exchange (ETDEWEB)

    Frangioni, John V [Wayland, MA


    A medical imaging system provides simultaneous rendering of visible light and fluorescent images. The system may employ dyes in a small-molecule form that remains in a subject's blood stream for several minutes, allowing real-time imaging of the subject's circulatory system superimposed upon a conventional, visible light image of the subject. The system may also employ dyes or other fluorescent substances associated with antibodies, antibody fragments, or ligands that accumulate within a region of diagnostic significance. In one embodiment, the system provides an excitation light source to excite the fluorescent substance and a visible light source for general illumination within the same optical guide that is used to capture images. In another embodiment, the system is configured for use in open surgical procedures by providing an operating area that is closed to ambient light. More broadly, the systems described herein may be used in imaging applications where a visible light image may be usefully supplemented by an image formed from fluorescent emissions from a fluorescent substance that marks areas of functional interest.

  16. Terahertz metamaterials

    Energy Technology Data Exchange (ETDEWEB)

    Chen, Hou-tong [Los Alamos National Laboratory; Taylor, Antoineete J [Los Alamos National Laboratory; Azad, Abul K [Los Alamos National Laboratory; O' Hara, John F [Los Alamos National Laboratory


    In this paper we present our recent developments in terahertz (THz) metamaterials and devices. Planar THz metamaterials and their complementary structures fabricated on suitable substrates have shown electric resonant response, which causes the band-pass or band-stop property in THz transmission and reflection. The operational frequency can be further tuned up to 20% upon photoexcitation of an integrated semiconductor region in the splitring resonators as the metamaterial elements. On the other hand, the use of semiconductors as metamaterial substrates enables dynamical control of metamaterial resonances through photoexcitation, and reducing the substrate carrier lifetime further enables an ultrafast switching recovery. The metamaterial resonances can also be actively controlled by application of a voltage bias when they are fabricated on semiconductor substrates with appropriate doping concentration and thickness. Using this electrically driven approach, THz modulation depth up to 80% and modulation speed of 2 MHz at room temperature have been demonstrated, which suggests practical THz applications.

  17. Significant performance enhancement in photoconductive terahertz optoelectronics by incorporating plasmonic contact electrodes. (United States)

    Berry, C W; Wang, N; Hashemi, M R; Unlu, M; Jarrahi, M


    Even though the terahertz spectrum is well suited for chemical identification, material characterization, biological sensing and medical imaging, practical development of these applications has been hindered by attributes of existing terahertz optoelectronics. Here we demonstrate that the use of plasmonic contact electrodes can significantly mitigate the low-quantum efficiency performance of photoconductive terahertz optoelectronics. The use of plasmonic contact electrodes offers nanoscale carrier transport path lengths for the majority of photocarriers, increasing the number of collected photocarriers in a subpicosecond timescale and, thus, enhancing the optical-to-terahertz conversion efficiency of photoconductive terahertz emitters and the detection sensitivity of photoconductive terahertz detectors. We experimentally demonstrate 50 times higher terahertz radiation powers from a plasmonic photoconductive emitter in comparison with a similar photoconductive emitter with non-plasmonic contact electrodes, as well as 30 times higher terahertz detection sensitivities from a plasmonic photoconductive detector in comparison with a similar photoconductive detector with non-plasmonic contact electrodes.

  18. Direct Measurements of Terahertz Meta-atoms with Near-Field Emission of Terahertz Waves (United States)

    Serita, Kazunori; Darmo, Juraj; Kawayama, Iwao; Murakami, Hironaru; Tonouchi, Masayoshi


    We present the direct measurements of terahertz meta-atoms, an elementary unit of metamaterials, by using locally generated terahertz waves in the near-field region. In contrast to a conventional far-field terahertz spectroscopy or imaging, our technique features the localized emission of coherent terahertz pulses on a sub-wavelength scale, which has a potential for visualizing details of dynamics of each meta-atom. The obtained data show the near-field coupling among the meta-atoms and the impact of the electric field distribution from the excited meta-atom to neighbor meta-atoms. The observable LC resonance response is enhanced with an increase of numbers of meta-atoms. Furthermore, our approach also has a potential for visualizing the individual mode of meta-atom at different terahertz irradiation spots. These data can help us to understand the important role of the meta-atom in metamaterials and develop the novel terahertz components and devices such as active terahertz metamaterial and compact, high-sensitive bio-sensor devices.

  19. Review in terahertz spectral analysis


    El Haddad, Josette; Bousquet, Bruno; Canioni, Lionel; Mounaix, Patrick


    International audience; Nowadays terahertz spectroscopy is a well-established technique and recent progresses in technology demonstrated that this new technique is useful for both fundamental research and industrial applications. Varieties of applications such as imaging, non destructive testing, quality control are about to be transferred to industry supported by permanent improvements from basic research. Since chemometrics is today routinely applied to IR spectroscopy, we discuss in this p...

  20. Miniaturized Time Domain Terahertz Non Destructive Evaluation for In-Orbit Inspection of Inflatable Habitats and Thermal Protection Systems Project (United States)

    National Aeronautics and Space Administration — Picometrix's time-domain terahertz (TD-THz) non-destructive evaluation (NDE) technology could be used to inspect space flight structures such as inflatable space...

  1. Tangible imaging systems (United States)

    Ferwerda, James A.


    We are developing tangible imaging systems1-4 that enable natural interaction with virtual objects. Tangible imaging systems are based on consumer mobile devices that incorporate electronic displays, graphics hardware, accelerometers, gyroscopes, and digital cameras, in laptop or tablet-shaped form-factors. Custom software allows the orientation of a device and the position of the observer to be tracked in real-time. Using this information, realistic images of threedimensional objects with complex textures and material properties are rendered to the screen, and tilting or moving in front of the device produces realistic changes in surface lighting and material appearance. Tangible imaging systems thus allow virtual objects to be observed and manipulated as naturally as real ones with the added benefit that object properties can be modified under user control. In this paper we describe four tangible imaging systems we have developed: the tangiBook - our first implementation on a laptop computer; tangiView - a more refined implementation on a tablet device; tangiPaint - a tangible digital painting application; and phantoView - an application that takes the tangible imaging concept into stereoscopic 3D.

  2. Implementation Strategy for the Deployment of Millimeter-Wavelength/Terahertz Technologies for Aviation Security

    National Research Council Canada - National Science Library


    .... This report--the third of four--focuses on currently maturing millimeter-wavelength/terahertz imaging and spectroscopy technologies that offer promise in meeting aviation security requirements...

  3. Terahertz applications in cultural heritage: case studies (United States)

    Giovannacci, D.; Martos-Levif, D.; Walker, G. C.; Menu, M.; Detalle, V.


    Terahertz (THz) spectroscopy and imaging is a non-destructive, non-contact, non-invasive technology emerging as a tool for the analysis of cultural heritage. THz Time Domain Spectroscopy (TDS) techniques have the ability to retrieve information from different layers within a stratified sample, that enable the identification of hidden sub-layers in the case of paints and mural paintings. In this paper, we present the THz TDS2 system developed in the European Commission's 7th Framework Program project CHARISMA [grant agreement no. 228330]. Bespoke single processing algorithms; including a deconvolution algorithm can be deployed to increase the resolution and the global performance of the system. The potential and impact of this work is demonstrated through two case studies of mural paintings, where the capability to reveal the stratigraphy of the artworks is demonstrated.

  4. Shearographic Imaging System. (United States)


    Shearography is a speckle shearing technique, developed recently I-5, which also allows a direct measurement of displacement gradient (strain) and it...D-A191 665 SNERROGRRPHIC IMROING SYSTEM () UNIVERSITY COLL OF / - NORTH URLES ORNOOR SCHOOL OF ELECTRONIC ENGINEERING SCIENCE 0 K DAS-GUPTA 91 JUN 97...CCESSION NO 11. TITLE -Khp* Swy Ootksl * , Shearographic Imaging System (unclassified) • 12. PERSON UTORS) Dr. D.K. Das-Gupta 138. TYPE OF REPORT 113b

  5. All-integrated terahertz modulators (United States)

    Degl'Innocenti, Riccardo; Kindness, Stephen J.; Beere, Harvey E.; Ritchie, David A.


    Terahertz (0.1-10 THz corresponding to vacuum wavelengths between 30 μm and 3 mm) research has experienced impressive progress in the last few decades. The importance of this frequency range stems from unique applications in several fields, including spectroscopy, communications, and imaging. THz emitters have experienced great development recently with the advent of the quantum cascade laser, the improvement in the frequency range covered by electronic-based sources, and the increased performance and versatility of time domain spectroscopic systems based on full-spectrum lasers. However, the lack of suitable active optoelectronic devices has hindered the ability of THz technologies to fulfill their potential. The high demand for fast, efficient integrated optical components, such as amplitude, frequency, and polarization modulators, is driving one of the most challenging research areas in photonics. This is partly due to the inherent difficulties in using conventional integrated modulation techniques. This article aims to provide an overview of the different approaches and techniques recently employed in order to overcome this bottleneck.

  6. Terahertz circular Airy vortex beams. (United States)

    Liu, Changming; Liu, Jinsong; Niu, Liting; Wei, Xuli; Wang, Kejia; Yang, Zhengang


    Vortex beams have received considerable research interests both in optical and millimeter-wave domain since its potential to be utilized in the wireless communications and novel imaging systems. Many well-known optical beams have been demonstrated to carry orbital angular momentum (OAM), such as Laguerre-Gaussian beams and high-order Bessel beams. Recently, the radially symmetric Airy beams that exhibit an abruptly autofocusing feature are also demonstrated to be capable of carrying OAM in the optical domain. However, due to the lack of efficient devices to manipulate terahertz (THz) beams, it could be a challenge to demonstrate the radially symmetric Airy beams in the THz domain. Here we demonstrate the THz circular Airy vortex beams (CAVBs) with a 0.3-THz continuous wave through 3D printing technology. Assisted by the rapidly 3D-printed phase plates, individual OAM states with topological charge l ranging from l = 0 to l = 3 and a multiplexed OAM state are successfully imposed into the radially symmetric Airy beams. We both numerically and experimentally investigate the propagation dynamics of the generated THz CAVBs, and the simulations agree well with the observations.

  7. Imaging Characteristics Of Electronic Imaging Systems (United States)

    Kriss, Michael A.


    Electronic imaging in the form of television has served the public for over 40 years. Television cameras have up to now used mostly photoconductive tubes to capture the live image. However, the last ten years have seen the advances in microelectronics, including VLSI technology, introduce newer, more flexible ways to record images via the solid state sensor. One version of the solid state sensor, the charge coupled device (CCD) has found its way into consumer electronic imaging, replacing the Super 8 movie system, and today, portable, commercial television cameras are starting to use CCD arrays instead of the more conventional photoconductive tubes. There are several electronic still cameras (ESC) on the market using solid state sensors, but due to the limited number of imaging sites or pixels on these imaging sensors, the quality is far below that of present photographic-based systems. This paper will consider imaging characteristics of photoconductive tubes (solid state imaging sensors) and how they compare to photographic film. Also, based on a system analysis, the requirements for a solid state sensor that will provide image quality equal to current photographic systems will be defined. The importance of digital image processing and digital image compression will also be discussed.

  8. Multispectral Panoramic Imaging System Project (United States)

    National Aeronautics and Space Administration — International Electronic Machines Corporation, a leader in the design of precision imaging systems, will develop an innovative multispectral, panoramic imaging...

  9. Quantitative Luminescence Imaging System

    Energy Technology Data Exchange (ETDEWEB)

    Batishko, C.R.; Stahl, K.A.; Fecht, B.A.


    The goal of the MEASUREMENT OF CHEMILUMINESCENCE project is to develop and deliver a suite of imaging radiometric instruments for measuring spatial distributions of chemiluminescence. Envisioned deliverables include instruments working at the microscopic, macroscopic, and life-sized scales. Both laboratory and field portable instruments are envisioned. The project also includes development of phantoms as enclosures for the diazoluminomelanin (DALM) chemiluminescent chemistry. A suite of either phantoms in a variety of typical poses, or phantoms that could be adjusted to a variety of poses, is envisioned. These are to include small mammals (rats), mid-sized mammals (monkeys), and human body parts. A complete human phantom that can be posed is a long-term goal of the development. Taken together, the chemistry and instrumentation provide a means for imaging rf dosimetry based on chemiluminescence induced by the heat resulting from rf energy absorption. The first delivered instrument, the Quantitative Luminescence Imaging System (QLIS), resulted in a patent, and an R&D Magazine 1991 R&D 100 award, recognizing it as one of the 100 most significant technological developments of 1991. The current status of the project is that three systems have been delivered, several related studies have been conducted, two preliminary human hand phantoms have been delivered, system upgrades have been implemented, and calibrations have been maintained. Current development includes sensitivity improvements to the microscope-based system; extension of the large-scale (potentially life-sized targets) system to field portable applications; extension of the 2-D large-scale system to 3-D measurement; imminent delivery of a more refined human hand phantom and a rat phantom; rf, thermal and imaging subsystem integration; and continued calibration and upgrade support.

  10. Nanoscale Laser Terahertz Emission Microscopy

    DEFF Research Database (Denmark)

    Klarskov, Pernille; Kim, Hyewon; Colvin, Vicki L.


    Laser terahertz emission microscopy (LTEM) has become a powerful tool for studying ultrafast dynamics and local fields in many different types of materials. This technique, which relies on acceleration of charge carriers in a material upon femtosecond excitation, can provide insight into the phys......Laser terahertz emission microscopy (LTEM) has become a powerful tool for studying ultrafast dynamics and local fields in many different types of materials. This technique, which relies on acceleration of charge carriers in a material upon femtosecond excitation, can provide insight...... into the physics of charge transport, built-in fields, grain boundaries or surface states. We describe a new implementation of LTEM with a spatial resolution in the nanoscale regime based on a scattering-type near-field tip-based approach. We observe a spectral reshaping of the signal compared to conventional LTEM......-size-limited spatial resolution of ∼20 nm by imaging a gold nanorod using terahertz emission from the underlying substrate. This work enables for the first time the possibility of performing LTEM measurements on individual nanostructures....

  11. Comparison of an electro-optical system and photo-conducting antenna employed as detectors of pulsed terahertz radiation by means of a new method for measuring spectral width

    Energy Technology Data Exchange (ETDEWEB)

    Grachev, Ya V; Osipova, M O; Bespalov, V G [ITMO University, St. Petersburg (Russian Federation)


    Two detection systems, electro-optical system and photoconducting system, are tested by the method suggested previously for determining the boundaries of broadband terahertz radiation in time-domain spectroscopy. From a series of measurements the error in determining the operation ranges is calculated. The terahertz spectrometer with an electro-optical detector based on a ZnTe (110) crystal of thickness 2 mm has the operation spectral range of 0.059 – 1.092 THz. The detector utilizing an iPCA-21-05-1000-800-h photo-conducting antenna with the same source of signal demonstrates a wider operation band ranging from 0.017 to 1.6 THz. The method developed makes it possible to experimentally compare the parameters of the considered terahertz spectrometers obtained under the same quality of adjustment. (laser applications and other topics in quantum electronics)

  12. Evaluation of human hairs with terahertz wave (United States)

    Serita, Kazunori; Murakami, Hironaru; Kawayama, Iwao; Takahashi, Yoshinori; Yoshimura, Masashi; Mori, Yusuke; Tonouchi, Masayoshi


    Single human hairs using a scanning laser terahertz (THz) imaging system are evaluated. The system features near-field THz emission and far-field THz detection. A sample is set in the vicinity of a two-dimensional THz emitter, and an excitation laser beam is scanned over the emitter via a galvanometer. By detecting the transmitted THz wave pulses that are locally generated at the irradiation spots of the excitation laser, we can obtain the THz transmission image and the spectrum of the sample with imaging time of 47 s for 512×512 pixels and maximum resolution of ˜27 μm. Using the system, we succeeded in observing the specific features of single human hairs in both the THz transmittance spectra and transmission images; it was found that the THz transmittance spectrum of gray hair shows a tendency of increase while that of black hair shows a decrease with increasing frequency above 1.2 THz. We could also observe the change of the moisture retention in the hair, and it is found that cuticles play one of the important roles in keeping moisture inside the hair. Those obtained data indicate that our system can be useful for evaluating single human hairs and those kinds of microscale samples.

  13. Regulatory effects of terahertz waves


    Vyacheslav F. Kirichuk; Alexey N. Ivanov


    There are modern data about biological effects of terahertz (THz) waves in this article. Items of interaction of THz waves with bio objects of different organization level. A complex of the data indicates that the realization of a THz wave effect in biosystems is possible at molecular, cellular, tissular, organ and system levels of regulation. There are data about changes in nervous and humoral regulation of an organism and metabolic effects of THz waves.

  14. Perfect terahertz absorber using fishnet based metafilm

    Energy Technology Data Exchange (ETDEWEB)

    Azad, Abul Kalam [Los Alamos National Laboratory; Shchegolkov, Dmitry Yu [Los Alamos National Laboratory; Chen, Houtong [Los Alamos National Laboratory; Taylor, Antoinette [Los Alamos National Laboratory; Smirnova, E I [Los Alamos National Laboratory; O' Hara, John F [Los Alamos National Laboratory


    We present a perfect terahertz (THz) absorber working for a broad-angle of incidence. The two fold symmetry of rectangular fishnet structure allows either complete absorption or mirror like reflection depending on the polarization of incident the THz beam. Metamaterials enable the ability to control the electromagnetic wave in a unique fashion by designing the permittivity or permeability of composite materials with desired values. Although the initial idea of metamaterials was to obtain a negative index medium, however, the evolution of metamaterials (MMs) offers a variety of practically applicable devices for controlling electromagnetic wave such as tunable filters, modulators, phase shifters, compact antenna, absorbers, etc. Terahertz regime, a crucial domain of the electromagnetic wave, is suffering from the scarcity of the efficient devices and might take the advantage of metamaterials. Here, we demonstrate design, fabrication, and characterization of a terahertz absorber based on a simple fishnet metallic film separated from a ground mirror plane by a dielectric spacer. Such absorbers are in particular important for bolometric terahertz detectors, high sensitivity imaging, and terahertz anechoic chambers. Recently, split-ring-resonators (SRR) have been employed for metamaterial-based absorbers at microwave and THz frequencies. The experimental demonstration reveals that such absorbers have absorptivity close to unity at resonance frequencies. However, the downside of these designs is that they all employ resonators of rather complicated shape with many fine parts and so they are not easy to fabricate and are sensitive to distortions.

  15. Polarization insensitive, broadband terahertz metamaterial absorber. (United States)

    Grant, James; Ma, Yong; Saha, Shimul; Khalid, Ata; Cumming, David R S


    We present the simulation, implementation, and measurement of a polarization insensitive broadband resonant terahertz metamaterial absorber. By stacking metal-insulator layers with differing structural dimensions, three closely positioned resonant peaks are merged into one broadband absorption spectrum. Greater than 60% absorption is obtained across a frequency range of 1.86 THz where the central resonance frequency is 5 THz. The FWHM of the device is 48%, which is two and half times greater than the FWHM of a single layer structure. Such metamaterials are promising candidates as absorbing elements for bolometric terahertz imaging.

  16. Terahertz applications: trends and challenges (United States)

    Robin, Thierry; Bouye, Clementine; Cochard, Jacques


    The objective of our work [1] was to determine the opportunities and challenges for Terahertz application development for the next years with a focus on systems: for homeland security and for Non Destructive Testing (NDT). Terahertz radiation has unique abilities and has been the subject of extensive research for many years. Proven concepts have emerged for numerous applications including Industrial NDT, Security, Health, Telecommunications, etc. Nevertheless, there has been no widely deployed application and Businesses based on THz technologies are still in their infancy. Some technological, market and industrial barriers are still to be broken. We summarize the final analysis and data: study of the technology trends and major bottlenecks per application segment, main challenges to be addressed in the next years, key opportunities for THz technologies based on market needs and requirements.

  17. Active metamaterials terahertz modulators and detectors

    CERN Document Server

    Rout, Saroj


    This book covers the theoretical background and experimental methods for engineers and physicist to be able to design, fabricate and characterize terahertz devices using metamaterials. Devices utilize mainstream semiconductor foundry processes to make them for communication and imaging applications. This book will provide engineers and physicists a comprehensive reference to construct such devices with general background in circuits and electromagnetics. The authors describe the design and construction of electromagnetic (EM) devices for terahertz frequencies (108-1010cycles/sec) by embedding solid state electronic devices into artificial metamaterials where each unit cell is only a fraction of the wavelength of the incident EM wave. The net effect is an electronically tunable bulk properties with effective electric (permittivity) and magnetic (permeability) that can be utilized to make novel devices to fill the terahertz gap.

  18. Terahertz frequency spectrum characterization of coherent heterodyne time-domain spectrometer (United States)

    Zhao, Ji; Zhang, Liang-liang; Luo, Yi-man; Wu, Tong; Zhang, Cunlin; Zhao, Yue-jin


    Terahertz wave which can provide innovative sensing and imaging techniques can obtain spectroscopic information unavailable at other wavelengths. The terahertz air-biased-coherent-detection (ABCD) method can achieve the third-order nonlinear susceptibility tensor to produce field-induced optical second harmonic photons. Therefore, the intense terahertz wave generated and detected by the laser-induced air plasma provides a promising ultra-broadband terahertz source and sensor for spectroscopy and imaging technique. Aiming at that purpose, an understanding of the frequency spectrum characterization of terahertz pulse is crucial. In this work, we investigated the variation of the THz pulse bandwidth measured through the third harmonic generation using the coherent detection scheme, by increasing the optical probe pulse power and biased electric field. A bandwidth broadening of the measured THz pulse is observed by increasing either the probe pulse power or the bias voltage strength. We speculate that a pulse shape change of the probe beam and a saturation effect during the second-harmonic generation might cause the bandwidth broaden with probe power. To further investigate the mechanism, we fixed the power of probe laser at 150mW and changed the bias voltage. The results show that the frequency spectrum width becomes wider gradually with the increasing of the bias voltage. A theoretical explaination shows that the bandwidth broadening with bias field might be introduced by a pulse shape change of the bias field induced second harmonic wave. This study reveals that we can control THz intensity and bandwidth by changing probe power and bias voltage in the ABCD system.

  19. Metamaterials for terahertz polarimetric devices

    Energy Technology Data Exchange (ETDEWEB)

    O' hara, John F [Los Alamos National Laboratory; Taylor, Antoinette J [Los Alamos National Laboratory; Smirnova, Evgenya [Los Alamos National Laboratory; Azad, Abul [Los Alamos National Laboratory


    We present experimental and numerical investigations of planar terahertz metamaterial structures designed to interact with the state of polarization. The dependence of metamaterial resonances on polarization results in unique amplitude and phase characteristics of the terahertz transmission, providing the basis for polarimetric terahertz devices. We highlight some potential applications for polarimetric devices and present simulations of a terahertz quarter-wave plate and a polarizing terahertz beam splitter. Although this work was performed at terahertz frequencies, it may find applications in other frequency ranges as well.

  20. Graphene hyperlens for terahertz radiation

    DEFF Research Database (Denmark)

    Andryieuski, Andrei; Lavrinenko, Andrei; Chigrin, Dmitry N.


    We propose a graphene hyperlens for the terahertz (THz) range. We employ and numerically examine a structured graphene-dielectric multilayered stack that is an analog of a metallic wire medium. As an example of the graphene hyperlens in action, we demonstrate an imaging of two point sources...... separated by a distance λ0/5. An advantage of such a hyperlens as compared to a metallic one is the tunability of its properties by changing the chemical potential of graphene. We also propose a method to retrieve the hyperbolic dispersion, check the effective medium approximation, and retrieve...

  1. Emulation and design of terahertz reflection-mode confocal scanning microscopy based on virtual pinhole (United States)

    Yang, Yong-fa; Li, Qi


    In the practical application of terahertz reflection-mode confocal scanning microscopy, the size of detector pinhole is an important factor that determines the performance of spatial resolution characteristic of the microscopic system. However, the use of physical pinhole brings some inconvenience to the experiment and the adjustment error has a great influence on the experiment result. Through reasonably selecting the parameter of matrix detector virtual pinhole (VPH), it can efficiently approximate the physical pinhole. By using this approach, the difficulty of experimental calibration is reduced significantly. In this article, an imaging scheme of terahertz reflection-mode confocal scanning microscopy that is based on the matrix detector VPH is put forward. The influence of detector pinhole size on the axial resolution of confocal scanning microscopy is emulated and analyzed. Then, the parameter of VPH is emulated when the best axial imaging performance is reached.

  2. Digital TV image enhancement system (United States)

    Biernson, G. A.


    Efficient, digital image-enhancement process has been developed for high-resolution slow-scan TV images. Scan converter is no longer subject to registration errors, which become more serious as resolution increases. To implement feedback image enhancement system, digital processing is used; otherwise there is excessive loss of image information, particularly in video delay lines.

  3. Terahertz spectroscopy of two-dimensional subwavelength plasmonic structures

    Energy Technology Data Exchange (ETDEWEB)

    Azad, Abul K [Los Alamos National Laboratory; Chen, Houtong [Los Alamos National Laboratory; Taylor, Antoinette [Los Alamos National Laboratory; O' Hara, John F [Los Alamos National Laboratory; Han, Jiaguang [OSU; Lu, Xinchao [OSU; Zhang, Weili [OSU


    The fascinating properties of plasmonic structures have had significant impact on the development of next generation ultracompact photonic and optoelectronic components. We study two-dimensional plasmonic structures functioning at terahertz frequencies. Resonant terahertz response due to surface plasmons and dipole localized surface plasmons were investigated by the state-of-the-art terahertz time domain spectroscopy (THz-TDS) using both transmission and reflection configurations. Extraordinary terahertz transmission was demonstrated through the subwavelength metallic hole arrays made from good conducting metals as well as poor metals. Metallic arrays m!lde from Pb, generally a poor metal, and having optically thin thicknesses less than one-third of a skin depth also contributed in enhanced THz transmission. A direct transition of a surface plasmon resonance from a photonic crystal minimum was observed in a photo-doped semiconductor array. Electrical controls of the surface plasmon resonances by hybridization of the Schottkey diode between the metallic grating and the semiconductor substrate are investigated as a function of the applied reverse bias. In addition, we have demonstrated photo-induced creation and annihilation of surface plasmons with appropriate semiconductors at room temperature. According to the Fano model, the transmission properties are characterized by two essential contributions: resonant excitation of surface plasmons and nonresonant direct transmission. Such plasmonic structures may find fascinating applications in terahertz imaging, biomedical sensing, subwavelength terahertz spectroscopy, tunable filters, and integrated terahertz devices.

  4. 77 FR 59941 - Prospective Grant of Exclusive License: Terahertz Scanning Systems for Cancer Pathology (United States)


    ... Systems for Cancer Pathology AGENCY: National Institutes of Health, Public Health Service, HHS. ACTION... systems for cancer pathology. Upon the expiration or termination of the exclusive evaluation option...

  5. PBG based terahertz antenna for aerospace applications

    CERN Document Server

    Choudhury, Balamati; Jha, Rakesh Mohan


    This book focuses on high-gain antennas in the terahertz spectrum and their optimization. The terahertz spectrum is an unallocated EM spectrum, which is being explored for a number of applications, especially to meet increasing demands of high data rates for wireless space communications. Space communication systems using the terahertz spectrum can resolve the problems of limited bandwidth of present wireless communications without radio-frequency interference. This book describes design of such high-gain antennas and their performance enhancement using photonic band gap (PBG) substrates. Further, optimization of antenna models using evolutionary algorithm based computational engine has been included. The optimized high-performance compact antenna may be used for various wireless applications, such as inter-orbital communications and on-vehicle satellite communications.

  6. Acoustic imaging system (United States)

    Smith, Richard W.


    An acoustic imaging system for displaying an object viewed by a moving array of transducers as the array is pivoted about a fixed point within a given plane. A plurality of transducers are fixedly positioned and equally spaced within a laterally extending array and operatively directed to transmit and receive acoustic signals along substantially parallel transmission paths. The transducers are sequentially activated along the array to transmit and receive acoustic signals according to a preestablished sequence. Means are provided for generating output voltages for each reception of an acoustic signal, corresponding to the coordinate position of the object viewed as the array is pivoted. Receptions from each of the transducers are presented on the same display at coordinates corresponding to the actual position of the object viewed to form a plane view of the object scanned.

  7. Reconfigurable metamaterials for terahertz wave manipulation (United States)

    Hashemi, Mohammed R.; Cakmakyapan, Semih; Jarrahi, Mona


    Reconfigurable metamaterials have emerged as promising platforms for manipulating the spectral and spatial properties of terahertz waves without being limited by the characteristics of naturally existing materials. Here, we present a comprehensive overview of various types of reconfigurable metamaterials that are utilized to manipulate the intensity, phase, polarization, and propagation direction of terahertz waves. We discuss various reconfiguration mechanisms based on optical, electrical, thermal, and mechanical stimuli while using semiconductors, superconductors, phase-change materials, graphene, and electromechanical structures. The advantages and disadvantages of different reconfigurable metamaterial designs in terms of modulation efficiency, modulation bandwidth, modulation speed, and system complexity are discussed in detail.

  8. Terahertz and Microwave Devices Based on the Photo-Excited Low Dimensional Electronic System (United States)


    electron system. This research aimed to advance the understanding of such radiation-induced phenomena in the two-dimensional electron system, while helping...photovoltaic detection of cyclotron resonance in the regime of radiation-induced magnetoresistance oscillations, Physical Review B, (06 2013...The Joseph Hadley Outstanding Advanced Graduate Student Award in Physics & Astronomy - 2012 • Olesya I. Sarajlic, The Outstanding Graduate

  9. Applications of terahertz-pulsed technology in the pharmaceutical industry (United States)

    Taday, Philip F.


    Coatings are applied to pharmaceutical tablets (or pills) to for either cosmetic or release control reasons. Cosmetic coatings control the colour or to mask the taste of an active ingredient; the thickness of these coating is not critical to the performance of the product. On the other hand the thickness and uniformity of a controlled release coating has been found affect the release of the active ingredient. In this work we have obtained from a pharmacy single brand of pantoprazole tablet and mapped them using terahertz pulsed imaging (TPI) prior to additional dissolution testing. Three terahertz parameters were derived for univariate analysis for each layer: coating thickness, terahertz electric field peak strength and terahertz interface index. These parameters were then correlated dissolution tested. The best fit was found to be with combined coating layer thickness of the inert layer and enteric coating. The commercial tablets showed a large variation in coating thickness.

  10. Quantum behavior of terahertz photoconductivity in silicon nanocrystals networks (United States)

    Pushkarev, V.; Ostatnický, T.; Němec, H.; Chlouba, T.; Trojánek, F.; Malý, P.; Zacharias, M.; Gutsch, S.; Hiller, D.; Kužel, P.


    Quantum-size effects are essential for understanding the terahertz conductivity of semiconductor nanocrystals, particularly at low temperatures. We derived a quantum mechanical expression for the linear terahertz response of nanocrystals; its introduction into an appropriate effective medium model provides a comprehensive microscopic approach for the analysis of terahertz conductivity spectra as a function of frequency, temperature, and excitation fluence. We performed optical pump-terahertz probe experiments in multilayer Si quantum dot networks with various degrees of percolation at 300 and 20 K and with variable pump fluence (initial carrier density) over nearly three orders of magnitude. Our theoretical approach was successfully applied to quantitatively interpret all the measured data within a single model. A careful data analysis made it possible to assess the distribution of sizes of nanocrystals participating to the photoconduction. We show and justify that such conductivity-weighted distribution may differ from the size distribution obtained by standard analysis of transmission electron microscopy images.

  11. Continuous wave terahertz systems exploiting 1.5 microm telecom technologies. (United States)

    Sartorius, B; Schlak, M; Stanze, D; Roehle, H; Künzel, H; Schmidt, D; Bach, H-G; Kunkel, R; Schell, M


    A fiber-assembled CW THz System operating at 1.5 microm is presented. High speed telecom photodiodes integrated with planar THz antennas serve as THz emitters with power up to 10 microW. Photoconductive antennas based on LT InGaAs/InAlAs multi-layer structures allow coherent detection. The system operates in a wide frequency range of 0.1 -1.6 THz. (c) 2009 Optical Society of America

  12. Metamaterials for terahertz polarimetric devices

    Energy Technology Data Exchange (ETDEWEB)

    O' hara, John F [Los Alamos National Laboratory; Taylor, Antoinette J [Los Alamos National Laboratory; Smirnova, Evgenya [Los Alamos National Laboratory; Azad, Abul [Los Alamos National Laboratory; Chen, Hou-tong [Los Alamos National Laboratory; Peralta, Xomalin G [SNL; Brener, Igal [SNL


    We present experimental and numerical investigations of planar terahertz metamaterial structures designed to interact with the state of polarization. The dependence of metamaterial resonances on polarization results in unique amplitude and phase characteristics of the terahertz transmission, providing the basis for polarimetric terahertz devices. We highlight some potential applications for polarimetric devices and present simulations of a terahertz quarter-wave plate and a polarizing terahertz beam splitter. Although this work was performed at tcrahertz frequencies, it may find applications in other frequency ranges as well.

  13. Telecom technology based continuous wave terahertz photomixing system with 105 decibel signal-to-noise ratio and 3.5 terahertz bandwidth. (United States)

    Göbel, Thorsten; Stanze, Dennis; Globisch, Björn; Dietz, Roman J B; Roehle, Helmut; Schell, Martin


    A modified photoconductive receiver significantly improves the performance of photomixing-based continuous wave (cw) THz systems driven at the optical telecommunication wavelength of 1.5 μm. The achieved signal-to-noise ratio of 105 dB at 100 GHz and 70 dB at 1 THz, both for an integration time of 200 ms, are to our knowledge the highest numbers reported in literature for any optoelectronic cw THz system, including classical setups operating at 800 nm. The developed receiver allows for combining low cost and high performance in one system for the first time to our knowledge.

  14. Art Painting Diagnostic Before Restoration with Terahertz and Millimeter Waves (United States)

    Guillet, Jean-Paul; Roux, M.; Wang, K.; Ma, X.; Fauquet, F.; Balacey, H.; Recur, B.; Darracq, F.; Mounaix, P.


    Art painting diagnostic is commonly performed using electromagnetic waves at wavelengths from terahertz to X-ray. These former techniques are essential in conservation and art history research, but they could be also very useful for restoring artwork. While most studies use time domain imaging technique, in this study, a painting has been investigated using both time domain imaging (TDI) and frequency-modulated continuous wave (FMCW) system in the millimeter frequency range. By applying these systems to a painting of the eighteenth century, we detect and analyze the structure of some defects. This study underlines the differences between FMCW and TDI. We present the advantages and disadvantages of each technique on a real artwork.

  15. OSPACS: Ultrasound image management system

    Directory of Open Access Journals (Sweden)

    Bessant Conrad


    Full Text Available Abstract Background Ultrasound scanning uses the medical imaging format, DICOM, for electronically storing the images and data associated with a particular scan. Large health care facilities typically use a picture archiving and communication system (PACS for storing and retrieving such images. However, these systems are usually not suitable for managing large collections of anonymized ultrasound images gathered during a clinical screening trial. Results We have developed a system enabling the accurate archiving and management of ultrasound images gathered during a clinical screening trial. It is based upon a Windows application utilizing an open-source DICOM image viewer and a relational database. The system automates the bulk import of DICOM files from removable media by cross-validating the patient information against an external database, anonymizing the data as well as the image, and then storing the contents of the file as a field in a database record. These image records may then be retrieved from the database and presented in a tree-view control so that the user can select particular images for display in a DICOM viewer or export them to external media. Conclusion This system provides error-free automation of ultrasound image archiving and management, suitable for use in a clinical trial. An open-source project has been established to promote continued development of the system.

  16. Terahertz response of two-dimensional charge carrier systems in GaAs-based heterostructures; Terahertz-Antwort von zweidimensionalen Ladungstraegersystemen in GaAs-basierten Heterostrukturen

    Energy Technology Data Exchange (ETDEWEB)

    Grunwald, Torben


    This thesis deals with the THz response of two-dimensional charge carrier systems in different semiconductor heterostructures under varying conditions. The utilized spectrometer is suitable for time-resolved optical pump - THz probe experiments, as well as for optical pump-probe experiments in the near infrared for identical conditions. It allows the investigation of the transverse dielectric function of both, a (GaIn)As/GaAs quantum well and a two-dimensional electron gas in a GaAs-based heterostructure. First, the THz response of an electron-hole plasma is examined for different carrier densities. The plasma is generated by interband transitions in a (GaIn)As/GaAs quantum well. The measured transverse dielectric function reveals that the plasma behaves in accordance with the classical Drude oscillator model. It also conforms to the microscopic theory of the THz response of corresponding many-body systems. Evidence of a plasma resonance in the negative imaginary part of the inverse dielectric function is found. The squared peak frequency of the resonance is proportional to the carrier density of the plasma. This behavior corresponds to the plasma frequency of a three-dimensional plasma. Overall, it can be shown that the transverse THz response of a two-dimensional electron-hole plasma behaves like the response of a three-dimensional plasma. Therefore, the transversal THz response of an electron-hole plasma seems to be independent of the dimension of the charge carrier system. Secondly, the behavior of the quantum well for a 1s-exciton dominated carrier system is investigated. A good agreement between experiment and microscopic theory is obtained for the dielectric function. The negative imaginary part of the inverse dielectric function shows a resonance at the intraexcitonic 1s-2p transition frequency, even in weakly excited excitonic systems. Increasing the carrier density leads to a plasma-like behavior of the system. However, in these densities a significant

  17. Multi-Spectral Materials: Hybridisation of Optical Plasmonic Filters and a Terahertz Metamaterial Absorber


    Mccrindle, Iain J.H.; Grant, James; Drysdale, Timothy D.; Cumming, David R. S.


    Multi-spectral materials, using hybridised plasmonic and metamaterial structures, can simultaneously exhibit unique resonant phenomena over several decades of wavelengths. A multi-spectral material that combines a plasmonic colour filter array and a terahertz metamaterial absorber into a single material is a promising prospect for a coaxial multi-spectral imager operating in the visible, near IR, and terahertz wavebands.

  18. Intelligent web image retrieval system (United States)

    Hong, Sungyong; Lee, Chungwoo; Nah, Yunmook


    Recently, the web sites such as e-business sites and shopping mall sites deal with lots of image information. To find a specific image from these image sources, we usually use web search engines or image database engines which rely on keyword only retrievals or color based retrievals with limited search capabilities. This paper presents an intelligent web image retrieval system. We propose the system architecture, the texture and color based image classification and indexing techniques, and representation schemes of user usage patterns. The query can be given by providing keywords, by selecting one or more sample texture patterns, by assigning color values within positional color blocks, or by combining some or all of these factors. The system keeps track of user's preferences by generating user query logs and automatically add more search information to subsequent user queries. To show the usefulness of the proposed system, some experimental results showing recall and precision are also explained.

  19. EDITORIAL: Photonic terahertz technology (United States)

    Lisauskas, Alvydas; Löffler, Torsten; Roskos, Hartmut G.


    femtosecond lasers operating at high repetition rate (~100 MHz). The system described by Planken et al was initially optimized for high-speed pixel-by-pixel THz imaging, which they do not describe here but rather focus on developments in THz microscopy. The second paper, by Kübler et al, presents pioneering work towards ultra-wide-bandwidth THz pulses which exhibit spectral content reaching far into the mid-IR, tremendously widening the covered frequency range, and hence shortening the time resolution, of THz spectroscopy. The third paper, by Löffler et al, deals with the state of the art in THz measurement systems relying on amplified laser pulses. Finally, Krotkus et al focus on low-temperature-grown (LT) GaAs, arguably the most important material for ultrafast optoelectronic switching and present in many THz sources and detectors, and in other emerging materials of similar kind. This leads directly to the second topic of this collection of papers, 'Continuous-Wave Photomixing Technology', based on THz-wave generation by down-conversion of continuous-wave (cw) laser radiation. This newer branch of THz photonics opens the possibility of obtaining tunable narrow-band THz radiation and of detecting it with high signal-to-noise ratio at room temperature. CW photomixing has received much attention over the last few years mainly because it has the potential to provide the compact and low-cost THz measurement systems needed for market applications beyond the scientific realm, with the sources of light for mixing being semiconductor (or fibre) lasers with or without optical amplifiers. Six papers outline recent developments in this subfield. We should also point towards a seventh paper, by Kawase et al, which is to be found in the section on 'Chemical and Biochemical Recognition', and which discusses an interesting hybrid approach generating tunable quasi-cw THz radiation with the help of nanosecond laser pulses. Of the six papers mentioned, the first, by Tani et al, summarizes

  20. Microelectromechanical Systems (MEMS) Photoacoustic (PA) Detector of Terahertz (THz) Radiation for Chemical Sensing (United States)


    potential between the top and bottom metal contacts when the cantilever is strained. This could yield in a more portable system, but the added layers...doesn’t normally adhere well to silicon and Ti does. Ti was chosen as the adhesion layer instead of other metals , such as Chromium, to be...slits 10 nm across. PA spectra of a blackened Teflon surface was collected at a modulation frequency of 17 Hz, sweeping at a rate of 50nm/min across

  1. An Optical and Terahertz Instrumentation System at the FAST LINAC at Fermilab

    Energy Technology Data Exchange (ETDEWEB)

    Thurman-Keup, R. [Fermilab; Lumpkin, A. H. [Fermilab; Thangaraj, J. [Fermilab


    FAST is a facility at Fermilab that consists of a photoinjector, two superconducting capture cavities, one superconducting ILC-style cryomodule, and a small ring for studying non-linear, integrable beam optics called IOTA. This paper discusses the layout for the optical transport system that provides optical radiation to an externally located streak camera for bunch length measurements, and THz radiation to a Martin-Puplett interferometer, also for bunch length measurements. It accepts radiation from two synchrotron radiation ports in a chicane bunch compressor and a diffraction/transition radiation screen downstream of the compressor. It also has the potential to access signal from a transition radiation screen or YAG screen after the spectrometer magnet for measurements of energy-time correlations. Initial results from both the streak camera and Martin-Puplett will be presented.

  2. Impulse radar imaging system for concealed object detection (United States)

    Podd, F. J. W.; David, M.; Iqbal, G.; Hussain, F.; Morris, D.; Osakue, E.; Yeow, Y.; Zahir, S.; Armitage, D. W.; Peyton, A. J.


    Electromagnetic systems for imaging concealed objects at checkpoints typically employ radiation at millimetre and terahertz frequencies. These systems have been shown to be effective and provide a sufficiently high resolution image. However there are difficulties and current electromagnetic systems have limitations particularly in accurately differentiating between threat and innocuous objects based on shape, surface emissivity or reflectivity, which are indicative parameters. In addition, water has a high absorption coefficient at millimetre wavelength and terahertz frequencies, which makes it more difficult for these frequencies to image through thick damp clothing. This paper considers the potential of using ultra wideband (UWB) in the low gigahertz range. The application of this frequency band to security screening appears to be a relatively new field. The business case for implementing the UWB system has been made financially viable by the recent availability of low-cost integrated circuits operating at these frequencies. Although designed for the communication sector, these devices can perform the required UWB radar measurements as well. This paper reports the implementation of a 2 to 5 GHz bandwidth linear array scanner. The paper describes the design and fabrication of transmitter and receiver antenna arrays whose individual elements are a type of antipodal Vivaldi antenna. The antenna's frequency and angular response were simulated in CST Microwave Studio and compared with laboratory measurements. The data pre-processing methods of background subtraction and deconvolution are implemented to improve the image quality. The background subtraction method uses a reference dataset to remove antenna crosstalk and room reflections from the dataset. The deconvolution method uses a Wiener filter to "sharpen" the returned echoes which improves the resolution of the reconstructed image. The filter uses an impulse response reference dataset and a signal

  3. Asymmetric planar terahertz metamaterials

    Energy Technology Data Exchange (ETDEWEB)

    Singh, Ramjan [Los Alamos National Laboratory; Al - Naib, Ibraheem A. I. [PHILIPPS UNIV; Koch, Martin [PHILIPPS UNIV; Zhang, Weili [OKLAHOMA STATE UNIV


    Using terahertz time-domain spectroscopy, we report an experimental observation of three distinct resonances in split ring resonators (SRRs) for both vertical and horizontal electric field polarizations at normal incidence. Breaking the symmetry in SRRs by gradually displacing the capacitive gap from the centre towards the comer of the ring allows for an 85% modulation of the fundamental inductive-capacitive (LC) resonance. Increasing asymmetry leads to the evolution of an otherwise inaccessible high quality factor electric quadrupole resonance that can be exploited for bio-sensing applications in the terahertz region.

  4. 3-D Cataract Imaging System (United States)

    Otten, L. J.; Soliz, P.; McMakin, I.; Greenaway, A.; Blanchard, P.; Ogawa, G.

    This paper describes a new adaptive optics instrument and associated diagnostic system for volumetric, in vivo imaging of the human lens and visual acuity characterization. The system is designed to allow one to capture simultaneous, in-focus images of the human lens at multiple "image planes." Based on the adaptation of a deformable grating originally developed for atmospheric turbulence measurements, the instrument will demonstrate an improvement over current techniques for imaging cortical, nuclear and posterior subcapsular cataracts. The system will characterize the human lens optically and will automatically produce an estimate of visual function as affected by the measured abnormalities in the lens. The process that Kestrel and DERA Malvern will use to demonstrate the key techniques for simultaneously acquiring in vivo lens imagery at multiple focus planes employs a surrogate lens. Eventually the camera could be considered as a replacement for most standard slit lamp instruments allowing them to be converted into a 3-D imaging system.

  5. MLA imaging systems (United States)

    Ando, K. J.


    The development of the enabling technology and instrument/mission definition phase for the application of advanced solid state sensors for future experimental remote sensing missions is discussed. The development of focal planes, instrument concept/design, mission studies, and service requirements and an imaging spectrometer technology and a Shuttle sortie mission definition are outlined.

  6. Underwater laser imaging system (UWLIS)

    Energy Technology Data Exchange (ETDEWEB)

    DeLong, M. [Lawrence Livermore National Lab., CA (United States)


    Practical limitations with underwater imaging systems area reached when the noise in the back scattered radiation generated in the water between the imaging system and the target obscures the spatial contrast and resolution necessary for target discovery and identification. The advent of high power lasers operating in the blue-green portion of the visible spectrum (oceanic transmission window) has led to improved experimental illumination systems for underwater imaging. Range-gated and synchronously scanned devices take advantage of the unique temporal and spatial coherence properties of laser radiation, respectively, to overcome the deleterious effects of common volume back scatter.

  7. Advanced Land Imager Assessment System (United States)

    Chander, Gyanesh; Choate, Mike; Christopherson, Jon; Hollaren, Doug; Morfitt, Ron; Nelson, Jim; Nelson, Shar; Storey, James; Helder, Dennis; Ruggles, Tim; hide


    The Advanced Land Imager Assessment System (ALIAS) supports radiometric and geometric image processing for the Advanced Land Imager (ALI) instrument onboard NASA s Earth Observing-1 (EO-1) satellite. ALIAS consists of two processing subsystems for radiometric and geometric processing of the ALI s multispectral imagery. The radiometric processing subsystem characterizes and corrects, where possible, radiometric qualities including: coherent, impulse; and random noise; signal-to-noise ratios (SNRs); detector operability; gain; bias; saturation levels; striping and banding; and the stability of detector performance. The geometric processing subsystem and analysis capabilities support sensor alignment calibrations, sensor chip assembly (SCA)-to-SCA alignments and band-to-band alignment; and perform geodetic accuracy assessments, modulation transfer function (MTF) characterizations, and image-to-image characterizations. ALIAS also characterizes and corrects band-toband registration, and performs systematic precision and terrain correction of ALI images. This system can geometrically correct, and automatically mosaic, the SCA image strips into a seamless, map-projected image. This system provides a large database, which enables bulk trending for all ALI image data and significant instrument telemetry. Bulk trending consists of two functions: Housekeeping Processing and Bulk Radiometric Processing. The Housekeeping function pulls telemetry and temperature information from the instrument housekeeping files and writes this information to a database for trending. The Bulk Radiometric Processing function writes statistical information from the dark data acquired before and after the Earth imagery and the lamp data to the database for trending. This allows for multi-scene statistical analyses.

  8. A coherent detection technique via optically biased field for broadband terahertz radiation (United States)

    Du, Hai-Wei; Dong, Jia-Meng; Liu, Yi; Shi, Chang-Cheng; Wu, Jing-Wei; Peng, Xiao-Yu


    We demonstrate theoretically and experimentally a coherent terahertz detection technique based on an optically biased field functioning as a local oscillator and a second harmonic induced by the terahertz electric field in the air sensor working in free space. After optimizing the polarization angle and the energy of the probe pulse, and filling the system with dry nitrogen, the terahertz radiation generated from a two-color-femtosecond-laser-pulses induced plasma filament is measured by this technique with a bandwidth of 0.1-10 THz and a signal-to-noise ratio of 48 dB. Our technique provides an alternative simple method for coherent broadband terahertz detection.

  9. Terahertz generation from graphite

    NARCIS (Netherlands)

    Ramakrishnan, G.; Chakkittakandy, R.; Planken, P.C.M.


    Generation of subpicosecond terahertz pulses is observed when graphite surfaces are illuminated with femtosecond near-infrared laser pulses. The nonlinear optical generation of THz pulses from graphite is unexpected since, in principle, the material possesses a centre of inversion symmetry.

  10. Determination of terahertz permittivity of dehydrated biological samples (United States)

    He, Yuezhi; Liu, Kai; Au, Corinna; Sun, Qiushuo; Parrott, Edward P. J.; PickWell-MacPherson, Emma


    A key step in transforming terahertz imaging to a practical medical imaging modality lies in understanding the interactions between terahertz (THz) waves and biological tissues. Most of the models in the literature use the permittivity of liquid water to simulate the THz-tissue interactions, but they often neglect contributions from the biological background such as proteins and lipids because dehydrated biological samples are experimentally difficult to prepare. In this work, we present a method to prepare thin and flat dehydrated samples which can be easily handled and measured in a transmission setup. Our results will provide fundamental parameters for modelling THz-tissue interactions.

  11. Physical characteristics modification of a SiGe-HBT semiconductor device for performance improvement in a terahertz detecting system (United States)

    Ghodsi, Hamed; Kaatuzian, Hassan


    In order to improve the performance of a pre-designed direct conversion terahertz detector which is implemented in a 0.25 μm-SiGe-BiCMOS process, we propose some slight modifications in the bipolar section of the SiGe device physical design. Comparison of our new proposed device and the previously reported device is done by SILVACO TCAD software simulation and we have used previous experimentally reported data to confirm our software simulations. Our proposed modifications in device structural design show a present device responsivity improvement of about 10% from 1 to 1.1 A/W while the bandwidth improvement is about 218 GHz. The minimum noise equivalent power at detector output is increased by about 14.3% and finally power consumption per pixel at the maximum responsivity is decreased by about 5%.

  12. Imaging Systems in TLE Research

    DEFF Research Database (Denmark)

    Allin, Thomas Højgaard; Neubert, Torsten; Laursen, Steen


    documented using the right equipment in the right way. This chapter provides an introduction to the concepts of low light imagers, and how they can be successfully applied in TLE research. As examples, we describe the 2003 and 2004 Spritewatch systems, which integrate low-light cameras with a digital...... processing system, and is controllable over the internet....

  13. Compact Imagers Based on MESSENGER's Mercury Dual Imaging System (United States)

    Chabot, N. L.; Murchie, S. L.; Hawkins, S. E.; Hayes, J. R.; Boldt, J. D.; Barnouin, O. S.; Heffernan, K.; Noble, M. W.


    MESSENGER's Mercury Dual Imaging System (MDIS) has acquired >130,000 images since launch in 2004, including the first images from Mercury orbit. MDIS, composed of two miniature cameras, has capabilities well matched to future planetary missions.

  14. EDITORIAL: Imaging systems and techniques Imaging systems and techniques (United States)

    Yang, Wuqiang; Giakos, George; Nikita, Konstantina; Pastorino, Matteo; Karras, Dimitrios


    The papers in this special issue focus on providing the state-of-the-art approaches and solutions to some of the most challenging imaging areas, such as the design, development, evaluation and applications of imaging systems, measuring techniques, image processing algorithms and instrumentation, with an ultimate aim of enhancing the measurement accuracy and image quality. This special issue explores the principles, engineering developments and applications of new imaging systems and techniques, and encourages broad discussion of imaging methodologies, shaping the future and identifying emerging trends. The multi-faceted field of imaging requires drastic adaptation to the rapid changes in our society, economy, environment and technological evolution. There is an urgent need to address new problems, which tend to be either static but complex, or dynamic, e.g. rapidly evolving with time, with many unknowns, and to propose innovative solutions. For instance, the battles against cancer and terror, monitoring of space resources and enhanced awareness, management of natural resources and environmental monitoring are some of the areas that need to be addressed. The complexity of the involved imaging scenarios and demanding design parameters, e.g. speed, signal-to-noise ratio (SNR), specificity, contrast, spatial resolution, scatter rejection, complex background and harsh environments, necessitate the development of a multi-functional, scalable and efficient imaging suite of sensors, solutions driven by innovation, and operation on diverse detection and imaging principles. Efficient medical imaging techniques capable of providing physiological information at the molecular level present another important research area. Advanced metabolic and functional imaging techniques, operating on multiple physical principles, and using high-resolution, high-selectivity nano-imaging methods, quantum dots, nanoparticles, biomarkers, nanostructures, nanosensors, micro-array imaging chips

  15. Three Dimensional Volumetric Terahertz Scanning for Aerospace Non Destructive Evaluation Project (United States)

    National Aeronautics and Space Administration — NASA and the aerospace industry are beginning to utilize terahertz (THz) reflection imaging (for example, examining the space shuttle external tank sprayed on foam...

  16. Intellectual system for images restoration (United States)

    Mardare, Igor


    Intelligence systems on basis of artificial neural networks and associative memory allow to solve effectively problems of recognition and restoration of images. However, within analytical technologies there are no dominating approaches of deciding of intellectual problems. Choice of the best technology depends on nature of problem, features of objects, volume of represented information about the object, number of classes of objects, etc. It is required to determine opportunities, preconditions and field of application of neural networks and associative memory for decision of problem of restoration of images and to use their supplementary benefits for further development of intelligence systems.

  17. Recent Progress in Terahertz Metasurfaces (United States)

    Al-Naib, Ibraheem; Withayachumnankul, Withawat


    In the past decade, the concept of metasurfaces has gradually dominated the field of metamaterials owing to their fascinating optical properties and simple planar geometries. At terahertz frequencies, the concept has been driven further by the availability of advanced micro-fabrication technologies that deliver sub-micron accuracy, well below the terahertz wavelengths. Furthermore, terahertz spectrometers with high dynamic range and amplitude and phase sensitivity provide valuable information for the study of metasurfaces in general. In this paper, we review recent progress in terahertz metasurfaces mainly in the last 5 years. The first part covers nonuniform metasurfaces that perform beamforming in reflection and transmission. In addition, we briefly overview four different methodologies that can be utilized in realizing high-quality-factor metasurfaces. We also describe two recent approaches to tuning the frequency response of terahertz metasurfaces using graphene as an active medium. Finally, we provide a brief summary and outlook for future developments in this rapidly progressing field.

  18. Observation of terahertz radiation coherently generated by acoustic waves (United States)

    Armstrong, Michael R.; Reed, Evan J.; Kim, Ki-Yong; Glownia, James H.; Howard, William M.; Piner, Edwin L.; Roberts, John C.


    Over the past decade, pioneering and innovative experiments using subpicosecond lasers have demonstrated the generation and detection of acoustic and shock waves in materials with terahertz frequencies, the highest possible frequency acoustic waves. In addition to groundbreaking demonstrations of acoustic solitons, these experiments have led to new techniques for probing the structure of thin films. Terahertz-frequency electromagnetic radiation has been used in applications as diverse as molecular and material excitations, charge transfer, imaging and plasma dynamics. However, at present, existing approaches to detect and measure the time dependence of terahertz-frequency strain waves in materials use direct optical probes-time-resolved interferometry or reflectrometry. Piezoelectric-based strain gauges have been used in acoustic shock and strain wave experiments for decades, but the time resolution of such devices is limited to ~100ps and slower, the timescale of electronic recording technology. We have recently predicted that terahertz-frequency acoustic waves can be detected by observing terahertz radiation emitted when the acoustic wave propagates past an interface between materials of differing piezoelectric coefficients. Here, we report the first experimental observation of this fundamentally new phenomenon and demonstrate that it can be used to probe structural properties of thin films.

  19. Millimeter- and terahertz-wave over fiber technologies for high-speed communication and non-telecom applications (United States)

    Kanno, Atsushi


    Millimeter-wave and terahertz-wave technologies are promising solutions for high-speed wireless communication as well as nondestructive imaging due to its high frequency (short wavelength) nature. In the study, we propose and demonstrate high-speed wireless communication in millimeter- and terahertz-wave bands adopted by advanced optical fiber communication technologies: combination of a radio over fiber (RoF) manner for generation of the signals and a high-speed digital signal processing implemented in a receiver. The RoF technique is also capable for a local-oscillator signal transport over the fiber to the remote sites. Fiber-remoted distributed radar system is also discussed in the paper.

  20. An effective way to reduce water absorption to terahertz (United States)

    Wu, Yaxiong; Su, Bo; He, Jingsuo; Zhang, Cong; Zhang, Hongfei; Zhang, Shengbo; Zhang, Cunlin


    Since many vibrations and rotational levels of biomolecules fall within the THz band, THz spectroscopy can be used to identify biological samples. In addition, most biomolecules need to maintain their biological activity in a liquid environment, but water as polar substance has strong absorption to the THz wave. Thus, it is difficult to detect the sample information in aqueous solution using THz wave. In order to prevent the information of biological samples were masked in the solution, many research methods were used to explore how to reduce the water absorption of terahertz. In this paper, we have developed a real-time chemical methodology through transmission Terahertz time-domain spectroscopy (THz-TDS) system. The material of Zeonor 1020r is used as substrate and cover plate, and PDMS as channel interlayer. The transmission of the empty microfluidic chip is more than 80% in the range of 0.2-2.6 THz by THz-TDS system. Then, experiments were carried out using chips, which were filled with different volumes of 1, 2- propanediol, and it has been proved that the microfluidic chip could reduce the water absorption of terahertz. Finally, in order to further explore the reduction of terahertz to water absorption, we inject different concentrations of electrolyte to the chip. The results show that with the addition of different electrolytes, terahertz transmission line has evident changes. It can be taken into account that the electrolyte has different effects about the hydrogen bonds in the aqueous solution. Some of them can promote water molecules clusters, while others destroy them. Based on the basis of microfluidic chip, the discovery of this phenomenon can provide a way that reduces water absorption of terahertz. This work has laid a solid foundation for the subsequent study in reducing water absorption of terahertz.

  1. Invisible Security Printing on Photoresist Polymer Readable by Terahertz Spectroscopy

    Directory of Open Access Journals (Sweden)

    Hee Jun Shin


    Full Text Available We experimentally modulate the refractive index and the absorption coefficient of an SU-8 dry film in the terahertz region by UV light (362 nm exposure with time dependency. Consequently, the refractive index of SU-8 film is increased by approximately 6% after UV light exposure. Moreover, the absorption coefficient also changes significantly. Using the reflective terahertz imaging technique, in addition, we can read security information printed by UV treatment on an SU-8 film that is transparent in the visible spectrum. From these results, we successfully demonstrate security printing and reading by using photoresist materials and the terahertz technique. This investigation would provide a new insight into anti-counterfeiting applications in fields that need security.

  2. Wideband Integrated Lens Antennas for Terahertz Deep Space Investigation

    NARCIS (Netherlands)

    Yurduseven, O.


    The Terahertz (THz) band is the portion of the spectrum that covers a frequency range from 300 GHz to 3 THz. The potential of this band has been proven for numerous type of applications including medical imaging, non-destructive testing, space observation, spectroscopy and security screening, thanks

  3. Imaging systems for geotechnical boreholes

    Energy Technology Data Exchange (ETDEWEB)

    Scott Thomson; S. Adam [CoalBed Concepts Pty Ltd. (Australia)


    The objective of this project was to develop a new system for evaluating geotechnical boreholes in underground mining. This approach was predicated on the demonstration of a commercial prototype imaging system (the Slim Borehole Scanner (SBS)) which is designed to be suitable for application in all standard geotechnical boreholes and is certified Intrinsically Safe (IS) in Europe. This project was designed to test this new imaging system in Australian conditions and critically compare the outcomes from the work with currently available technologies. A key aspect of the project was the assessment of the likely impact the imaging system has on current practices and recommendations for improved methods of geotechnical assessment in underground operations. A comprehensive field-testing program of the SBS was undertaken to evaluate its suitability for application in Australian conditions. Test work was completed at BHPB Illawarra Appin Colliery and Xstrata Coal Tahmoor Colliery. The Slim Borehole Scanner (SBS) was found to be a useful tool for enhancing the capability of Australian underground mine operators to assess roof conditions. The SBS is a significant advance on existing qualitative assessment methods such as the Borescope, and is complementary to existing direct measurement methods such as Tel-tales and Gel-extensometers. It is recommended that the SBS system undergo Australian intrinsic safety approval and be adopted as a routine part of the geotechnical engineer's arsenal in assessing roof control issues in Australian mines.

  4. Review of GaN-based devices for terahertz operation (United States)

    Ahi, Kiarash


    GaN provides the highest electron saturation velocity, breakdown voltage, operation temperature, and thus the highest combined frequency-power performance among commonly used semiconductors. The industrial need for compact, economical, high-resolution, and high-power terahertz (THz) imaging and spectroscopy systems are promoting the utilization of GaN for implementing the next generation of THz systems. As it is reviewed, the mentioned characteristics of GaN together with its capabilities of providing high two-dimensional election densities and large longitudinal optical phonon of ˜90 meV make it one of the most promising semiconductor materials for the future of the THz emitters, detectors, mixers, and frequency multiplicators. GaN-based devices have shown capabilities of operation in the upper THz frequency band of 5 to 12 THz with relatively high photon densities in room temperature. As a result, THz imaging and spectroscopy systems with high resolution and deep depth of penetration can be realized through utilizing GaN-based devices. A comprehensive review of the history and the state of the art of GaN-based electronic devices, including plasma heterostructure field-effect transistors, negative differential resistances, hetero-dimensional Schottky diodes, impact avalanche transit times, quantum-cascade lasers, high electron mobility transistors, Gunn diodes, and tera field-effect transistors together with their impact on the future of THz imaging and spectroscopy systems is provided.

  5. Graphene plasmonics for tunable terahertz metamaterials. (United States)

    Ju, Long; Geng, Baisong; Horng, Jason; Girit, Caglar; Martin, Michael; Hao, Zhao; Bechtel, Hans A; Liang, Xiaogan; Zettl, Alex; Shen, Y Ron; Wang, Feng


    Plasmons describe collective oscillations of electrons. They have a fundamental role in the dynamic responses of electron systems and form the basis of research into optical metamaterials. Plasmons of two-dimensional massless electrons, as present in graphene, show unusual behaviour that enables new tunable plasmonic metamaterials and, potentially, optoelectronic applications in the terahertz frequency range. Here we explore plasmon excitations in engineered graphene micro-ribbon arrays. We demonstrate that graphene plasmon resonances can be tuned over a broad terahertz frequency range by changing micro-ribbon width and in situ electrostatic doping. The ribbon width and carrier doping dependences of graphene plasmon frequency demonstrate power-law behaviour characteristic of two-dimensional massless Dirac electrons. The plasmon resonances have remarkably large oscillator strengths, resulting in prominent room-temperature optical absorption peaks. In comparison, plasmon absorption in a conventional two-dimensional electron gas was observed only at 4.2 K (refs 13, 14). The results represent a first look at light-plasmon coupling in graphene and point to potential graphene-based terahertz metamaterials.

  6. Geometric phase shaping of terahertz vortex beams. (United States)

    Minasyan, Amalya; Trovato, Clément; Degert, Jérôme; Freysz, Eric; Brasselet, Etienne; Abraham, Emmanuel


    We propose a topological beam-shaping strategy of terahertz (THz) beams using geometric phase elements made of space-variant birefringent slabs. Quasi-monochromatic THz vortex beams are produced and characterized both in amplitude and phase from the reconstructed real-time two-dimensional imaging of the electric field. Nonseparable superpositions of such vortex beams are also obtained and characterized by two-dimensional polarimetric analysis. These results emphasize the versatility of the spin-orbit electromagnetic toolbox to prepare on-demand structured light endowed with polarization-controlled orbital angular momentum content in the THz domain, which should find many uses in future THz technologies.

  7. Self-phase modulation of a single-cycle terahertz pulse by nonlinear free-carrier response in a semiconductor

    DEFF Research Database (Denmark)

    Turchinovich, Dmitry; Hvam, Jørn Märcher; Hoffmann, Matthias C.


    We investigate the self-phase modulation (SPM) of a single-cycle terahertz pulse in a semiconductor, using bulk n-GaAs as a model system. The SPM arises from the heating of free electrons in the electric field of the terahertz pulse, leading to an ultrafast reduction of the plasma frequency...... the broad spectrum of the terahertz pulse, with the zero-nonlinearity point defined by the electron momentum relaxation rate. We also observed the nonlinear spectral broadening and compression of the terahertz pulse....

  8. Optical secure image verification system based on ghost imaging (United States)

    Wu, Jingjing; Haobogedewude, Buyinggaridi; Liu, Zhengjun; Liu, Shutian


    The ghost imaging can perform Fourier-space filtering by tailoring the configuration. We proposed a novel optical secure image verification system based on this theory with the help of phase matched filtering. In the verification process, the system key and the ID card which contain the information of the correct image and the information to be verified are put in the reference and the test paths, respectively. We demonstrate that the ghost imaging configuration can perform an incoherent correlation between the system key and the ID card. The correct verification manifests itself with a correlation peak in the ghost image. The primary image and the image to be verified are encrypted and encoded into pure phase masks beforehand for security. Multi-image secure verifications can also be implemented in the proposed system.

  9. Superiority of terahertz over infrared transmission through bandages and burn wound ointments

    Energy Technology Data Exchange (ETDEWEB)

    Suen, Jonathan Y., E-mail:; Padilla, Willie J. [Department of Electrical and Computer Engineering, Duke University, Durham, North Carolina 27708 (United States)


    Terahertz electromagnetic waves have long been proposed to be ideal for spectroscopy and imaging through non-polar dielectric materials that contain no water. Terahertz radiation may thus be useful for monitoring burn and wound injury recovery, as common care treatments involve application of both a clinical dressing and topical ointment. Here, we investigate the optical properties of typical care treatments in the millimeter wave (150–300 GHz), terahertz (0.3–3 THz), and infrared (14.5–0.67 μm) ranges of the electromagnetic spectrum. We find that THz radiation realizes low absorption coefficients and high levels of transmission compared to infrared wavelengths, which were strongly attenuated. Terahertz imaging can enable safe, non-ionizing, noninvasive monitoring of the healing process directly through clinical dressings and recovery ointments, minimizing the frequency of dressing changes and thus increasing the rate of the healing process.

  10. A flexible and wearable terahertz scanner (United States)

    Suzuki, D.; Oda, S.; Kawano, Y.


    Imaging technologies based on terahertz (THz) waves have great potential for use in powerful non-invasive inspection methods. However, most real objects have various three-dimensional curvatures and existing THz technologies often encounter difficulties in imaging such configurations, which limits the useful range of THz imaging applications. Here, we report the development of a flexible and wearable THz scanner based on carbon nanotubes. We achieved room-temperature THz detection over a broad frequency band ranging from 0.14 to 39 THz and developed a portable THz scanner. Using this scanner, we performed THz imaging of samples concealed behind opaque objects, breakages and metal impurities of a bent film and multi-view scans of a syringe. We demonstrated a passive biometric THz scan of a human hand. Our results are expected to have considerable implications for non-destructive and non-contact inspections, such as medical examinations for the continuous monitoring of health conditions.

  11. The effect of terahertz electromagnetic radiation on cardiovascular system and orbital vessels in age-related macular degeneration

    Directory of Open Access Journals (Sweden)

    K. U. Eremenko


    Full Text Available Aim.To study the effect of terahertz (THz radiation at atmospheric oxygen frequency (129 GHz on cardiovascular and hemodynamic parameters of orbital arteries following the irradiation of bioactive points in healthy volunteers and age-related macular degeneration (AMD patients.Materials and methods. 18 healthy volunteers (36 eyes and 20 AMD patients (34 eyes were examined. Blood pressure (BP, heart rate (HR, systolic and diastolic blood flow velocities, resistance index (RI in orbital arteries before and following THz radiation of two bioactive points VB1 and TR23 at atmospheric oxygen frequency 129 GHz in continuouswave generation mode were measured.Results. First data on the effect of THz waves at atmospheric oxygen irradiation and absorption molecular spectrum frequency (129 GHz in continuous wave generation mode on ocular hemodynamics in healthy persons and AMD patients are presented. Following THz irradiation at atmospheric oxygen frequency (129 GHz, common hemodynamicparameters (BP, HR decreased. In healthy volunteers, systolic and diastolic BP reduced by 22.83±4.09 and 8.82±0.98 mm Hg, respectively (р<0.05, HR reduced by 6.11±0.15 bpm (р<0.05. In AMD patients, systolic and diastolic BP significantly decreased by 45.55±0.43 and 9.56±1.42 mm Hg, respectively (р<0.05, HR decreased by 6.15±1.1 bpm (р<0.05. In AMD patients, systolic blood flow velocity significantly reduced by 2.89±0.1 cm / sec in central retinal artery and increased by0.9‑5.97 cm / sec in short posterior ciliary arteries and ophthalmic artery. RI in these vessels decreased by 0.13, 0.11, 0.13 and 0.12, respectively.Conclusion. THz waves at atmospheric oxygen irradiation and absorption molecular spectrum frequency (129 GHz are safe and cause no side effects on general health of healthy volunteers and AMD patients. Besides, this method improves ocular hemodynamics.

  12. The effect of terahertz electromagnetic radiation on cardiovascular system and orbital vessels in age-related macular degeneration

    Directory of Open Access Journals (Sweden)

    K. U. Eremenko


    Full Text Available Aim.To study the effect of terahertz (THz radiation at atmospheric oxygen frequency (129 GHz on cardiovascular and hemodynamic parameters of orbital arteries following the irradiation of bioactive points in healthy volunteers and age-related macular degeneration (AMD patients.Materials and methods. 18 healthy volunteers (36 eyes and 20 AMD patients (34 eyes were examined. Blood pressure (BP, heart rate (HR, systolic and diastolic blood flow velocities, resistance index (RI in orbital arteries before and following THz radiation of two bioactive points VB1 and TR23 at atmospheric oxygen frequency 129 GHz in continuouswave generation mode were measured.Results. First data on the effect of THz waves at atmospheric oxygen irradiation and absorption molecular spectrum frequency (129 GHz in continuous wave generation mode on ocular hemodynamics in healthy persons and AMD patients are presented. Following THz irradiation at atmospheric oxygen frequency (129 GHz, common hemodynamicparameters (BP, HR decreased. In healthy volunteers, systolic and diastolic BP reduced by 22.83±4.09 and 8.82±0.98 mm Hg, respectively (р<0.05, HR reduced by 6.11±0.15 bpm (р<0.05. In AMD patients, systolic and diastolic BP significantly decreased by 45.55±0.43 and 9.56±1.42 mm Hg, respectively (р<0.05, HR decreased by 6.15±1.1 bpm (р<0.05. In AMD patients, systolic blood flow velocity significantly reduced by 2.89±0.1 cm / sec in central retinal artery and increased by0.9‑5.97 cm / sec in short posterior ciliary arteries and ophthalmic artery. RI in these vessels decreased by 0.13, 0.11, 0.13 and 0.12, respectively.Conclusion. THz waves at atmospheric oxygen irradiation and absorption molecular spectrum frequency (129 GHz are safe and cause no side effects on general health of healthy volunteers and AMD patients. Besides, this method improves ocular hemodynamics.

  13. Laser Feedback Interferometry as a Tool for Analysis of Granular Materials at Terahertz Frequencies: Towards Imaging and Identification of Plastic Explosives

    Directory of Open Access Journals (Sweden)

    She Han


    Full Text Available We propose a self-consistent method for the analysis of granular materials at terahertz (THz frequencies using a quantum cascade laser. The method is designed for signals acquired from a laser feedback interferometer, and applied to non-contact reflection-mode sensing. Our technique is demonstrated using three plastic explosives, achieving good agreement with reference measurements obtained by THz time-domain spectroscopy in transmission geometry. The technique described in this study is readily scalable: replacing a single laser with a small laser array, with individual lasers operating at different frequencies will enable unambiguous identification of select materials. This paves the way towards non-contact, reflection-mode analysis and identification of granular materials at THz frequencies using quantum cascade lasers.

  14. Image and information management system (United States)

    Robertson, Tina L. (Inventor); Raney, Michael C. (Inventor); Dougherty, Dennis M. (Inventor); Kent, Peter C. (Inventor); Brucker, Russell X. (Inventor); Lampert, Daryl A. (Inventor)


    A system and methods through which pictorial views of an object's configuration, arranged in a hierarchical fashion, are navigated by a person to establish a visual context within the configuration. The visual context is automatically translated by the system into a set of search parameters driving retrieval of structured data and content (images, documents, multimedia, etc.) associated with the specific context. The system places ''hot spots'', or actionable regions, on various portions of the pictorials representing the object. When a user interacts with an actionable region, a more detailed pictorial from the hierarchy is presented representing that portion of the object, along with real-time feedback in the form of a popup pane containing information about that region, and counts-by-type reflecting the number of items that are available within the system associated with the specific context and search filters established at that point in time.

  15. Resonant metallic nanostructures for enhanced terahertz spectroscopy

    KAUST Repository

    Toma, A.


    We present our recent studies on terahertz resonant dipole nanoantennas. Exploiting the localization and enhancement capabilities of these devices, we introduce an effective method to perform terahertz spectroscopy on an extremely small number of nano-objects.

  16. Design of low noise imaging system (United States)

    Hu, Bo; Chen, Xiaolai


    In order to meet the needs of engineering applications for low noise imaging system under the mode of global shutter, a complete imaging system is designed based on the SCMOS (Scientific CMOS) image sensor CIS2521F. The paper introduces hardware circuit and software system design. Based on the analysis of key indexes and technologies about the imaging system, the paper makes chips selection and decides SCMOS + FPGA+ DDRII+ Camera Link as processing architecture. Then it introduces the entire system workflow and power supply and distribution unit design. As for the software system, which consists of the SCMOS control module, image acquisition module, data cache control module and transmission control module, the paper designs in Verilog language and drives it to work properly based on Xilinx FPGA. The imaging experimental results show that the imaging system exhibits a 2560*2160 pixel resolution, has a maximum frame frequency of 50 fps. The imaging quality of the system satisfies the requirement of the index.

  17. Space-Ready Advanced Imaging System Project (United States)

    National Aeronautics and Space Administration — In this Phase II effort Toyon will increase the state-of-the-art for video/image systems. This will include digital image compression algorithms as well as system...

  18. Multi-channel medical imaging system

    Energy Technology Data Exchange (ETDEWEB)

    Frangioni, John V


    A medical imaging system provides simultaneous rendering of visible light and fluorescent images. The system may employ dyes in a small-molecule form that remain in the subject's blood stream for several minutes, allowing real-time imaging of the subject's circulatory system superimposed upon a conventional, visible light image of the subject. The system may provide an excitation light source to excite the fluorescent substance and a visible light source for general illumination within the same optical guide used to capture images. The system may be configured for use in open surgical procedures by providing an operating area that is closed to ambient light. The systems described herein provide two or more diagnostic imaging channels for capture of multiple, concurrent diagnostic images and may be used where a visible light image may be usefully supplemented by two or more images that are independently marked for functional interest.

  19. Multi-channel medical imaging system

    Energy Technology Data Exchange (ETDEWEB)

    Frangioni, John V.


    A medical imaging system provides simultaneous rendering of visible light and fluorescent images. The system may employ dyes in a small-molecule form that remain in a subject's blood stream for several minutes, allowing real-time imaging of the subject's circulatory system superimposed upon a conventional, visible light image of the subject. The system may provide an excitation light source to excite the fluorescent substance and a visible light source for general illumination within the same optical guide used to capture images. The system may be configured for use in open surgical procedures by providing an operating area that is closed to ambient light. The systems described herein provide two or more diagnostic imaging channels for capture of multiple, concurrent diagnostic images and may be used where a visible light image may be usefully supplemented by two or more images that are independently marked for functional interest.

  20. Multilayer Graphene for Waveguide Terahertz Modulator

    DEFF Research Database (Denmark)

    Khromova, I.; Andryieuski, Andrei; Lavrinenko, Andrei


    We study terahertz to infrared electromagnetic properties of multilayer graphene/dielectric artificial medium and present a novel concept of terahertz modulation at midinfrared wavelengths. This approach allows the realization of high-speed electrically controllable terahertz modulators based...... on hollow waveguide sections filled with multilayer graphene....

  1. Active terahertz metamaterial devices (United States)

    Chen, Houtong; Padilla, Willie John; Averitt, Richard Douglas; O'Hara, John F.; Lee, Mark


    Metamaterial structures are taught which provide for the modulation of terahertz frequency signals. Each element within an array of metamaterial (MM) elements comprises multiple loops and at least one gap. The MM elements may comprise resonators with conductive loops and insulated gaps, or the inverse in which insulated loops are present with conductive gaps; each providing useful transmissive control properties. The metamaterial elements are fabricated on a semiconducting substrate configured with a means of enhancing or depleting electrons from near the gaps of the MM elements. An on to off transmissivity ratio of about 0.5 is achieved with this approach. Embodiments are described in which the MM elements incorporated within a Quantum Cascade Laser (QCL) to provide surface emitting (SE) properties.

  2. Metasurfaces in terahertz waveband (United States)

    He, Jingwen; Zhang, Yan


    Metasurface, composed of subwavelength antennas, allows us to obtain arbitrary permittivity and permeability in electromagnetic (EM) waveband. It can be used to control the polarization, frequency, amplitude, and phase of the EM wave. Conventional terahertz (THz) components, such as high-impedance silicon lens, polyethylene lens, and quartz wave plate, rely on the phase accumulation along the wave propagation to reshape the THz wavefront. The metasurface employs the localized surface plasmon resonance to modulate the wavefront. Compared with conventional THz components, metasurface has the advantages of being ultrathin, ultralight, and low cost. In recent years, a large number of THz devices based on metasurface have been proposed. We review in broad outline the metasurface devices in the THz region and describe the progress of static and tunable THz field-modulated metasurfaces in detail. Finally, we discuss current challenges and opportunities in this rapidly developing research field.

  3. Photoconductive, dielectric and percolation properties of anodic TiO2 nanotubes studied by terahertz spectroscopy (United States)

    Kuchařík, Jiří; Sopha, Hanna; Krbal, Milos; Rychetský, Ivan; Kužel, Petr; Macak, Jan M.; Němec, Hynek


    Self-organized layers of anodic TiO2 nanotubes were investigated using time-resolved terahertz spectroscopy in the steady state and upon photoexcitation. The interpretation of the conductivity spectra is based on the response of confined charges calculated by the Monte-Carlo method and on the evaluated distribution of the probing terahertz electric field in the heterogeneous structure. We show that the charge motion perpendicular to the nanotube axis is confined on ~10 nm scale, and that the charge mobility inside these confinement areas is comparable to that observed in a bulk anatase crystal. The electrical connectivity between individual nanotubes assessed from the terahertz spectra qualitatively correlates with the geometry observed in SEM images. The measured transient terahertz transmission spectra feature an apparent resonance; we demonstrate that it is not a signature of a new low-energy excitation but a geometrical effect of Fabry–Pérot interferences in the photoexcited slab.

  4. Detection of hidden objects using a real-time 3-D millimeter-wave imaging system (United States)

    Rozban, Daniel; Aharon, Avihai; Levanon, Assaf; Abramovich, Amir; Yitzhaky, Yitzhak; Kopeika, N. S.


    Millimeter (mm)and sub-mm wavelengths or terahertz (THz) band have several properties that motivate their use in imaging for security applications such as recognition of hidden objects, dangerous materials, aerosols, imaging through walls as in hostage situations, and also in bad weather conditions. There is no known ionization hazard for biological tissue, and atmospheric degradation of THz radiation is relatively low for practical imaging distances. We recently developed a new technology for the detection of THz radiation. This technology is based on very inexpensive plasma neon indicator lamps, also known as Glow Discharge Detector (GDD), that can be used as very sensitive THz radiation detectors. Using them, we designed and constructed a Focal Plane Array (FPA) and obtained recognizable2-dimensional THz images of both dielectric and metallic objects. Using THz wave it is shown here that even concealed weapons made of dielectric material can be detected. An example is an image of a knife concealed inside a leather bag and also under heavy clothing. Three-dimensional imaging using radar methods can enhance those images since it can allow the isolation of the concealed objects from the body and environmental clutter such as nearby furniture or other people. The GDDs enable direct heterodyning between the electric field of the target signal and the reference signal eliminating the requirement for expensive mixers, sources, and Low Noise Amplifiers (LNAs).We expanded the ability of the FPA so that we are able to obtain recognizable 2-dimensional THz images in real time. We show here that the THz detection of objects in three dimensions, using FMCW principles is also applicable in real time. This imaging system is also shown here to be capable of imaging objects from distances allowing standoff detection of suspicious objects and humans from large distances.

  5. Handheld microwave bomb-detecting imaging system (United States)

    Gorwara, Ashok; Molchanov, Pavlo


    Proposed novel imaging technique will provide all weather high-resolution imaging and recognition capability for RF/Microwave signals with good penetration through highly scattered media: fog, snow, dust, smoke, even foliage, camouflage, walls and ground. Image resolution in proposed imaging system is not limited by diffraction and will be determined by processor and sampling frequency. Proposed imaging system can simultaneously cover wide field of view, detect multiple targets and can be multi-frequency, multi-function. Directional antennas in imaging system can be close positioned and installed in cell phone size handheld device, on small aircraft or distributed around protected border or object. Non-scanning monopulse system allows dramatically decrease in transmitting power and at the same time provides increased imaging range by integrating 2-3 orders more signals than regular scanning imaging systems.

  6. Terahertz Fibres and Functional FibreI-Based Devices

    DEFF Research Database (Denmark)

    Bao, Hualong

    The area of Terahertz (THz) radiation has been proved to be a very promising utility for a wide range of applications. However, since current THz systems predominantly utilize freespace propagation, the large size and requirement of careful alignment thus increasing the complexity are the drawbac...

  7. Optical feedback effects on terahertz quantum cascade lasers: modelling and applications (United States)

    Rakić, Aleksandar D.; Lim, Yah Leng; Taimre, Thomas; Agnew, Gary; Qi, Xiaoqiong; Bertling, Karl; Han, She; Wilson, Stephen J.; Kundu, Iman; Grier, Andrew; Ikonić, Zoran; Valavanis, Alexander; Demić, Aleksandar; Keeley, James; Li, Lianhe H.; Linfield, Edmund H.; Davies, A. Giles; Harrison, Paul; Ferguson, Blake; Walker, Graeme; Prow, Tarl; Indjin, Dragan; Soyer, H. Peter


    Terahertz (THz) quantum cascade lasers (QCLs) are compact sources of radiation in the 1-5 THz range with significant potential for applications in sensing and imaging. Laser feedback interferometry (LFI) with THz QCLs is a technique utilizing the sensitivity of the QCL to the radiation reflected back into the laser cavity from an external target. We will discuss modelling techniques and explore the applications of LFI in biological tissue imaging and will show that the confocal nature of the QCL in LFI systems, with their innate capacity for depth sectioning, makes them suitable for skin diagnostics with the well-known advantages of more conventional confocal microscopes. A demonstration of discrimination of neoplasia from healthy tissue using a THz, LFI-based system in the context of melanoma is presented using a transgenic mouse model.

  8. Role of collagen in terahertz absorption in skin (United States)

    Tewari, Priyamvada; Culjat, Martin O.; Taylor, Zachary D.; Suen, Jonathan Y.; Burt, Benjamin O.; Lee, Hua; Brown, Elliott R.; Grundfest, Warren S.; Singh, Rahul S.


    Reflective terahertz (THz) imaging may potentially become a valuable tool in determining skin hydration due to its non-ionizing photon energy, high sensitivity to water concentration and ability to penetrate through clothing. The high absorption coefficient of water in the THz range is responsible for contrast between substances with lesser or higher degrees of water saturation. Water content, as well as collagen fiber arrangement, varies between different layers of skin. This study sought to determine whether the high THz absorption in water could be exploited to distinguish between these layers. Porcine skin specimens were sectioned into samples of increasing thickness, with the undersides corresponding to different layers in skin. The undersides of the samples were scanned using a THz imaging system operating at a center frequency of 0.5 THz with 0.125 THz of noise-equivalent bandwidth at a standoff of 4 cm and a spot size of 13 mm. Collagen solutions of varying hydrations were also prepared and raster scanned with the same system. The reflectivity of the deeper layers of skin was found to be higher than that of the upper layers, indicating that the deeper layers are more hydrated. The collagen solutions with higher hydration also had higher THz reflectivity. These results suggested that THz is able to distinguish between different layers of skin based on water content and the nature of its association with components in skin.

  9. Laboratory testing & measurement on optical imaging systems

    CSIR Research Space (South Africa)

    Theron, B


    Full Text Available The purpose of the workshop was for participants to interactively discuss (with regard to optical imaging or optical imaging systems): Local end-user needs; What those needs imply for associated new & existing laboratory testing & measurement...

  10. Towards a proton imaging system

    Energy Technology Data Exchange (ETDEWEB)

    Civinini, C., E-mail: Carlo.Civinini@fi.infn.i [INFN, sezione di Firenze, via G. Sansone 1, I-50019 Sesto Fiorentino (Italy); Brianzi, M. [INFN, sezione di Firenze, via G. Sansone 1, I-50019 Sesto Fiorentino (Italy); Bruzzi, M. [INFN, sezione di Firenze, via G. Sansone 1, I-50019 Sesto Fiorentino (Italy); Dipartimento di Energetica, Universita degli Studi di Firenze, via S. Marta 3, I-50139 Firenze (Italy); Bucciolini, M. [INFN, sezione di Firenze, via G. Sansone 1, I-50019 Sesto Fiorentino (Italy); Dipartimento di Fisiopatologia Clinica, Universita degli Studi di Firenze, v.le Morgagni 85, I-50134 Firenze (Italy); Candiano, G. [INFN, Laboratori Nazionali del Sud, via S. Sofia 62, I-95123 Catania (Italy); Capineri, L. [Dipartimento di Elettronica e Telecomunicazioni, Universita degli Studi di Firenze, via S. Marta 3, I-50139 Firenze (Italy); Cirrone, G.A.P.; Cuttone, G. [INFN, Laboratori Nazionali del Sud, via S. Sofia 62, I-95123 Catania (Italy); Lo Presti, D. [Dipartimento di Fisica, Universita degli Studi di Catania, via S. Sofia 64, I-95123 Catania (Italy); INFN, sezione di Catania, via S. Sofia 64, I-95123 Catania (Italy); Marrazzo, L. [INFN, sezione di Firenze, via G. Sansone 1, I-50019 Sesto Fiorentino (Italy); Dipartimento di Fisiopatologia Clinica, Universita degli Studi di Firenze, v.le Morgagni 85, I-50134 Firenze (Italy); Mazzaglia, E. [INFN, Laboratori Nazionali del Sud, via S. Sofia 62, I-95123 Catania (Italy); Menichelli, D.; Pieri, S. [INFN, sezione di Firenze, via G. Sansone 1, I-50019 Sesto Fiorentino (Finland) (Italy); Dipartimento di Energetica, Universita degli Studi di Firenze, via S. Marta 3, I-50139 Firenze (Italy); Randazzo, N. [INFN, sezione di Catania, via S. Sofia 64, I-95123 Catania (Italy); Sipala, V. [Dipartimento di Fisica, Universita degli Studi di Catania, via S. Sofia 64, I-95123 Catania (Italy); INFN, sezione di Catania, via S. Sofia 64, I-95123 Catania (Italy)


    Hadron therapy for tumor treatment is nowadays used in several medical centres. The main advantage in using protons or light ions beams is the possibility of tightly shaping the radiation dose to the target volume. Presently the spatial accuracy of the therapy is limited by the uncertainty in stopping power distribution, which is derived, for each treatment, from the photon attenuation coefficients measured by X-ray tomography. A direct measurement of the stopping powers will help in reducing this uncertainty. This can be achieved by using a proton beam and a detection system able to reconstruct a tomography image of the patient. As a first step towards such a system an apparatus able to perform a proton transmission radiography (pCR) has been designed. It consists of a silicon microstrip tracker, measuring proton trajectories, and a YAG:Ce calorimeter to determine the particle residual energy. Proton beam and laboratory tests have been performed on the system components prototypes: the main results will be shown and discussed.

  11. Multi-band terahertz metasurface absorber (United States)

    Wang, Xuying; Wang, Qingmin; Dong, Guoyan; Hao, Yanan; Lei, Ming; Bi, Ke


    A terahertz metasurface perfect absorber with multi-band performance is demonstrated. The absorber is composed of a ground plane and four split-ring resonators (SRRs) with different dimensions, separated by a dielectric spacer. The numerical simulation results illustrate that the proposed absorber has four distinct absorption peaks at resonance frequencies of 4.24, 5.66, 7.22, and 8.97 THz, with absorption rates of 96.8%, 99.3%, 97.3%, and 99.9%, respectively. Moreover, the corresponding full width at half-maximum (FWHM) values are about 0.27, 0.35, 0.32, and 0.42 THz, respectively, which are much broader than those of previously reported absorbers. Besides, the calculated magnetic field distributions allow us to understand the absorption mechanism in detail. The effects of incident angle and azimuthal angle on the absorber are also investigated. The results show that the proposed absorber is partially sensitive to the incident angle, which makes this design promising for practical applications in terahertz imagers and detectors.

  12. Tunable metamaterial dual-band terahertz absorber (United States)

    Luo, C. Y.; Li, Z. Z.; Guo, Z. H.; Yue, J.; Luo, Q.; Yao, G.; Ji, J.; Rao, Y. K.; Li, R. K.; Li, D.; Wang, H. X.; Yao, J. Q.; Ling, F. R.


    We report a design of a temperature controlled tunable dual band terahertz absorber. The compact single unit cell consists of two nested closed square ring resonators and a layer metallic separated by a substrate strontium titanate (STO) dielectric layer. It is found that the absorber has two distinctive absorption peaks at frequencies 0.096 THz and 0.137 THz, whose peaks are attained 97% and 75%. Cooling the absorber from 400 K to 250 K causes about 25% and 27% shift compared to the resonance frequency of room temperature, when we cooling the temperature to 150 K, we could attained both the two tunabilities exceeding 53%. The frequency tunability is owing to the variation of the dielectric constant of the low-temperature co-fired ceramic (LTCC) substrate. The mechanism of the dual band absorber is attributed to the overlapping of dual resonance frequencies, and could be demonstrated by the distributions of the electric field. The method opens up avenues for designing tunable terahertz devices in detection, imaging, and stealth technology.

  13. Subwavelength micropillar array terahertz lasers. (United States)

    Krall, Michael; Brandstetter, Martin; Deutsch, Christoph; Detz, Hermann; Andrews, Aaron Maxwell; Schrenk, Werner; Strasser, Gottfried; Unterrainer, Karl


    We report on micropillar-based terahertz lasers with active pillars that are much smaller than the emission wavelength. These micropillar array lasers correspond to scaled-down band-edge photonic crystal lasers forming an active photonic metamaterial. In contrast to photonic crystal lasers which use significantly larger pillar structures, lasing emission is not observed close to high-symmetry points in the photonic band diagram, but in the effective medium regime. We measure stimulated emission at 4 THz for micropillar array lasers with pillar diameters of 5 µm. Our results not only demonstrate the integration of active subwavelength optics in a terahertz laser, but are also an important step towards the realization of nanowire-based terahertz lasers.

  14. Developing stereo image based robot control system

    Energy Technology Data Exchange (ETDEWEB)

    Suprijadi,; Pambudi, I. R.; Woran, M.; Naa, C. F; Srigutomo, W. [Department of Physics, FMIPA, InstitutTeknologi Bandung Jl. Ganesha No. 10. Bandung 40132, Indonesia (Indonesia)


    Application of image processing is developed in various field and purposes. In the last decade, image based system increase rapidly with the increasing of hardware and microprocessor performance. Many fields of science and technology were used this methods especially in medicine and instrumentation. New technique on stereovision to give a 3-dimension image or movie is very interesting, but not many applications in control system. Stereo image has pixel disparity information that is not existed in single image. In this research, we proposed a new method in wheel robot control system using stereovision. The result shows robot automatically moves based on stereovision captures.

  15. Uncovering the Terahertz Spectrum of Copper Sulfate Pentahydrate. (United States)

    Ruggiero, Michael T; Korter, Timothy M


    Terahertz vibrational spectroscopy has evolved into a powerful tool for the detection and characterization of transition metal sulfate compounds, specifically for its ability to differentiate between various hydrated forms with high specificity. Copper(II) sulfate is one such system where multiple crystalline hydrates have had their terahertz spectra fully assigned, and the unique spectral fingerprints of the forms allows for characterization of multicomponent systems with relative ease. Yet the most commonly occurring form, copper(II) sulfate pentahydrate (CuSO4·5H2O), has proven elusive due to the presence of a broad absorption across much of the terahertz region, making the unambiguous identification of its spectral signature difficult. Here, it is shown that the sub-100 cm(-1) spectrum of CuSO4·5H2O is obscured by absorption from adsorbed water and that controlled drying reveals sharp underlying features. The crystalline composition of the samples was monitored in parallel by X-ray diffraction as a function of drying time, supporting the spectroscopic results. Finally, the terahertz spectrum of CuSO4·5H2O was fully assigned using solid-state density functional theory simulations, helping attribute the additional absorptions that appear after excessive drying to formation of CuSO4·3H2O.

  16. Detection of Ionic liquid using terahertz time-domain spectroscopy (United States)

    Wang, Cuicui; Zhao, Xiaojing; Liu, Shangjian; Zuo, Jian; Zhang, Cunlin


    Terahertz (THz, THz+1012Hz) spectroscopy is a far-infrared analytical technology with spectral bands locating between microware and infrared ranges. Being of excellent transmission, non-destruction and high discrimination, this technology has been applied in various fields such as physics, chemistry, nondestructive detection, communication, biomedicine public security. Terahertz spectrum is corresponding with vibration and rotation of liquid molecules, which is suitable to identify and study the liquid molecular dynamics. It is as a powerful spectral detection technology, terahertz time-domain spectroscopy is widely used in solution detection. can enable us to extract the material parameters or dielectric spectrum that show material micro-structure and dynamics by measuring amplitude and phase from coherent terahertz pulses. Ionic liquid exists in most biological tissues, and it is very important for life. It has recently been suggested that near-fired terahertz ionic contrast microscopy can be employed to image subtle changes in ionic concentrations arising from neuronal activity. In this paper, we detected Ionic liquid with different concentrations at room temperature by THz-TDS technique in the range of 0.2-1.5 THz. The liquid cell with a thickness of 0.2mm is made of quartz. The absorption coefficient, refractive index and dielectric function of solutions can be extracted based on THz-TDS. We use an expanded model for fitting the dielectric function based on a combination of a Debye relation for the anions and cations. We find A linear increase of the real and imaginary part of the dielectric function compared with pure water with increasing ion concentrations. A good agreement between the model and the experimental results is obtained. By means of dielectric relaxation process, it was found that the characteristic time of molecular movement and the information related to the liquid molecular structure and movement was obtained.

  17. Physical Optics Based Computational Imaging Systems (United States)

    Olivas, Stephen Joseph

    There is an ongoing demand on behalf of the consumer, medical and military industries to make lighter weight, higher resolution, wider field-of-view and extended depth-of-focus cameras. This leads to design trade-offs between performance and cost, be it size, weight, power, or expense. This has brought attention to finding new ways to extend the design space while adhering to cost constraints. Extending the functionality of an imager in order to achieve extraordinary performance is a common theme of computational imaging, a field of study which uses additional hardware along with tailored algorithms to formulate and solve inverse problems in imaging. This dissertation details four specific systems within this emerging field: a Fiber Bundle Relayed Imaging System, an Extended Depth-of-Focus Imaging System, a Platform Motion Blur Image Restoration System, and a Compressive Imaging System. The Fiber Bundle Relayed Imaging System is part of a larger project, where the work presented in this thesis was to use image processing techniques to mitigate problems inherent to fiber bundle image relay and then, form high-resolution wide field-of-view panoramas captured from multiple sensors within a custom state-of-the-art imager. The Extended Depth-of-Focus System goals were to characterize the angular and depth dependence of the PSF of a focal swept imager in order to increase the acceptably focused imaged scene depth. The goal of the Platform Motion Blur Image Restoration System was to build a system that can capture a high signal-to-noise ratio (SNR), long-exposure image which is inherently blurred while at the same time capturing motion data using additional optical sensors in order to deblur the degraded images. Lastly, the objective of the Compressive Imager was to design and build a system functionally similar to the Single Pixel Camera and use it to test new sampling methods for image generation and to characterize it against a traditional camera. These computational

  18. Broadband terahertz fiber directional coupler

    DEFF Research Database (Denmark)

    Nielsen, Kristian; Rasmussen, Henrik K.; Jepsen, Peter Uhd


    We present the design of a short broadband fiber directional coupler for terahertz (THz) radiation and demonstrate a 3 dB coupler with a bandwidth of 0:6 THz centered at 1:4 THz. The broadband coupling is achieved by mechanically downdoping the cores of a dual-core photonic crystal fiber by micro......We present the design of a short broadband fiber directional coupler for terahertz (THz) radiation and demonstrate a 3 dB coupler with a bandwidth of 0:6 THz centered at 1:4 THz. The broadband coupling is achieved by mechanically downdoping the cores of a dual-core photonic crystal fiber...

  19. A terahertz grid frequency doubler


    Moussessian, Alina; Wanke, Michael C.; Li, Yongjun; Chiao, Jung-Chih; Allen, S. James; Crowe, Thomas W.; Rutledge, David B.


    We present a 144-element terahertz quasi-optical grid frequency doubler. The grid is a planar structure with bow-tie antennas as a unit cell, each loaded with a planar Schottky diode. The maximum output power measured for this grid is 24 mW at 1 THz for 3.1-μs 500-GHz input pulses with a peak input power of 47 W. An efficiency of 0.17% for an input power of 6.3 W and output power of 10.8 mW is measured. To date, this is the largest recorded output power for a multiplier at terahertz frequenci...

  20. Terahertz wave manipulation with metamaterials based on metal and graphene

    DEFF Research Database (Denmark)

    Andryieuski, Andrei; Malureanu, Radu; Zalkovskij, Maksim


    The terahertz (THz) technology provides with exciting possibilities for spectroscopy, food quality control, defense, communication and biomedical imaging [1]. Being relatively young (the massive exploitation of the THz range began only in the beginning of 1990-ies), the THz science demands...... for active and passive materials and devices. Metamaterials, metal-dielectric artificial composites, propose wide possibilities for achieving unconventional electromagnetic properties, not found in nature. Moreover, metamaterials constructed of graphene, a monolayer of carbon atoms, allow for tunable...

  1. Ultrafast terahertz control of extreme tunnel currents through single atoms on a silicon surface (United States)

    Jelic, Vedran; Iwaszczuk, Krzysztof; Nguyen, Peter H.; Rathje, Christopher; Hornig, Graham J.; Sharum, Haille M.; Hoffman, James R.; Freeman, Mark R.; Hegmann, Frank A.


    Ultrafast control of current on the atomic scale is essential for future innovations in nanoelectronics. Extremely localized transient electric fields on the nanoscale can be achieved by coupling picosecond duration terahertz pulses to metallic nanostructures. Here, we demonstrate terahertz scanning tunnelling microscopy (THz-STM) in ultrahigh vacuum as a new platform for exploring ultrafast non-equilibrium tunnelling dynamics with atomic precision. Extreme terahertz-pulse-driven tunnel currents up to 107 times larger than steady-state currents in conventional STM are used to image individual atoms on a silicon surface with 0.3 nm spatial resolution. At terahertz frequencies, the metallic-like Si(111)-(7 × 7) surface is unable to screen the electric field from the bulk, resulting in a terahertz tunnel conductance that is fundamentally different than that of the steady state. Ultrafast terahertz-induced band bending and non-equilibrium charging of surface states opens new conduction pathways to the bulk, enabling extreme transient tunnel currents to flow between the tip and sample.

  2. Image portion identification methods, image parsing methods, image parsing systems, and articles of manufacture (United States)

    Lassahn, Gordon D.; Lancaster, Gregory D.; Apel, William A.; Thompson, Vicki S.


    Image portion identification methods, image parsing methods, image parsing systems, and articles of manufacture are described. According to one embodiment, an image portion identification method includes accessing data regarding an image depicting a plurality of biological substrates corresponding to at least one biological sample and indicating presence of at least one biological indicator within the biological sample and, using processing circuitry, automatically identifying a portion of the image depicting one of the biological substrates but not others of the biological substrates.

  3. Differential CMOS Sub-Terahertz Detector with Subthreshold Amplifier. (United States)

    Yang, Jong-Ryul; Han, Seong-Tae; Baek, Donghyun


    We propose a differential-type complementary metal-oxide-semiconductor (CMOS) sub-terahertz (THz) detector with a subthreshold preamplifier. The proposed detector improves the voltage responsivity and effective signal-to-noise ratio (SNR) using the subthreshold preamplifier, which is located between the differential detector device and main amplifier. The overall noise of the detector for the THz imaging system is reduced by the preamplifier because it diminishes the noise contribution of the main amplifier. The subthreshold preamplifier is self-biased by the output DC voltage of the detector core and has a dummy structure that cancels the DC offsets generated by the preamplifier itself. The 200 GHz detector fabricated using 0.25 μm CMOS technology includes a low drop-out regulator, current reference blocks, and an integrated antenna. A voltage responsivity of 2020 kV/W and noise equivalent power of 76 pW/√Hz are achieved using the detector at a gate bias of 0.5 V, respectively. The effective SNR at a 103 Hz chopping frequency is 70.9 dB with a 0.7 W/m² input signal power density. The dynamic range of the raster-scanned THz image is 44.59 dB.

  4. Generating, Separating and Polarizing Terahertz Vortex Beams via Liquid Crystals with Gradient-Rotation Directors

    Directory of Open Access Journals (Sweden)

    Shi-Jun Ge


    Full Text Available Liquid crystal (LC is a promising candidate for terahertz (THz devices. Recently, LC has been introduced to generate THz vortex beams. However, the efficiency is intensely dependent on the incident wavelength, and the transformed THz vortex beam is usually mixed with the residual component. Thus, a separating process is indispensable. Here, we introduce a gradient blazed phase, and propose a THz LC forked polarization grating that can simultaneously generate and separate pure THz vortices with opposite circular polarization. The specific LC gradient-rotation directors are implemented by a photoalignment technique. The generated THz vortex beams are characterized with a THz imaging system, verifying features of polarization controllability. This work may pave a practical road towards generating, separating and polarizing THz vortex beams, and may prompt applications in THz communications, sensing and imaging.

  5. Terahertz Real-Time Off-Axis Digital Holography with Zoom Function (United States)

    Hou, Lei; Han, Xiao-Wei; Yang, Lei; Shi, Wei


    We present a terahertz (THz) real-time digital holographic system with zoom function worked at 0.17 THz. The magnification factor ranges from 1 to 2. In the imaging experiment, the resolution is 2 mm with the magnification factor of 1.2. A metal sheet with F-shaped hollow is used as a sample, and its THz holograms are reconstructed by our developed algorithm based on the angular spectrum theorem, and the qualities of the THz images under different conditions are compared. Supported by the National Natural Science Foundation of China under Grant Nos 61575161 and 61427814, the Foundation of Shaanxi Key Science and Technology Innovation Team under Grant No 2014KTC-13, the Special Financial Grant from the China Postdoctoral Science Foundation under Grant No 2013T60883, and the Equipment Pre-research Fund Project of China under Grant No 9140C370504140C37175.

  6. Multi region based image retrieval system

    Indian Academy of Sciences (India)

    with images. CBIR also referred as Query By Image Content (QBIC) is the application of auto- matic retrieval of images from a database based on the visual content such as colour, texture or shape. CBIR exploits techniques from computer vision, machine learning, database systems, data mining, information theory, statistics ...

  7. A multi-element THz imaging system

    DEFF Research Database (Denmark)

    Eichhorn, Finn; Høgstedt, Lasse; Buron, Jonas Christian Due


    We report on a broadband multi-element THz imaging system based on fiber-coupled, integrated photoconductive emitters and detectors. 32 detectors and 32 emitters are arranged in a planar array. Advanced image reconstruction algorithms are employed to reconstruct an object in the imaging plane....

  8. CW-THz vector spectroscopy and imaging system based on 1.55-µm fiber-optics. (United States)

    Kim, Jae-Young; Song, Ho-Jin; Yaita, Makoto; Hirata, Akihiko; Ajito, Katsuhiro


    We present a continuous-wave terahertz (THz) vector spectroscopy and imaging system based on a 1.5-µm fiber optic uni-traveling-carrier photodiode and InGaAs photo-conductive receiver. Using electro-optic (EO) phase modulators for THz phase control with shortened optical paths, the system achieves fast vector measurement with effective phase stabilization. Dynamic ranges of 100 dB · Hz and 75 dB · Hz at 300 GHz and 1 THz, and phase stability of 1.5° per minute are obtained. With the simultaneous measurement of absorbance and relative permittivity, we demonstrate non-destructive analyses of pharmaceutical cocrystals inside tablets within a few minutes.

  9. Radar cross section measurements using terahertz waves

    DEFF Research Database (Denmark)

    Iwaszczuk, Krzysztof; Heiselberg, Henning; Jepsen, Peter Uhd


    Radar cross sections at terahertz frequencies are measured on scale models of aircrafts. A time domain broadband THz system generates freely propagating THz pulses measured with sub-picosecond time resolution. The THz radiation is generated using fs laser pulses by optical rectification in a lith......Radar cross sections at terahertz frequencies are measured on scale models of aircrafts. A time domain broadband THz system generates freely propagating THz pulses measured with sub-picosecond time resolution. The THz radiation is generated using fs laser pulses by optical rectification...... in a lithium niobate crystal with application of the tilted wave front method, resulting in high electric field THz pulses with a broad band spectrum from 100 GHz up to 4 THz. The corresponding wave lengths are two orders of magnitude smaller than normal radars and we therefore use scale models of size 5-10 cm...... in order to measure realistic radar cross sections. RCS polar and azimuthal angle plots of F-16 and F-35 are presented....

  10. Dynamic Gesture Recognition with a Terahertz Radar Based on Range Profile Sequences and Doppler Signatures

    Directory of Open Access Journals (Sweden)

    Zhi Zhou


    Full Text Available The frequency of terahertz radar ranges from 0.1 THz to 10 THz, which is higher than that of microwaves. Multi-modal signals, including high-resolution range profile (HRRP and Doppler signatures, can be acquired by the terahertz radar system. These two kinds of information are commonly used in automatic target recognition; however, dynamic gesture recognition is rarely discussed in the terahertz regime. In this paper, a dynamic gesture recognition system using a terahertz radar is proposed, based on multi-modal signals. The HRRP sequences and Doppler signatures were first achieved from the radar echoes. Considering the electromagnetic scattering characteristics, a feature extraction model is designed using location parameter estimation of scattering centers. Dynamic Time Warping (DTW extended to multi-modal signals is used to accomplish the classifications. Ten types of gesture signals, collected from a terahertz radar, are applied to validate the analysis and the recognition system. The results of the experiment indicate that the recognition rate reaches more than 91%. This research verifies the potential applications of dynamic gesture recognition using a terahertz radar.

  11. Controlling software development of CW terahertz target scattering properties measurements based on LabVIEW (United States)

    Fan, Chang-Kun; Li, Qi; Zhou, Yi; Zhao, Yong-Peng; Chen, De-Ying


    With the development of terahertz technology and increasing studies on terahertz target scattering properties, research on terahertz target scattering properties measurements attracts more and more attention. In this paper, to solve problems in the detection process, we design a controlling software for Continuous-Wave (CW) terahertz target scattering properties measurements. The software is designed and programmed based on LabVIEW. The software controls the whole system, involving the switch between the target and the calibration target, the rotation of target, collection, display and storage of the initial data and display, storage of the data after the calibration process. The experimental results show that the software can accomplish the expected requirement, enhance the speed of scattering properties measurements and reduce operation errors.

  12. Ultra-broadband near-field antenna for terahertz plasmonic applications

    Energy Technology Data Exchange (ETDEWEB)

    Polischuk, O. V., E-mail:; Popov, V. V., E-mail: [Russian Academy of Sciences, Saratov Branch of the Kotel’nikov Institute of Radio Engineering and Electronics (Russian Federation); Knap, W. [Université Montpellier 2 and CNRS, Laboratoire Charles Coulomb, UMR 5221 (France)


    A new type of ultra-broadband near-field antenna for terahertz frequencies is proposed. This antenna is a short-period planar metal array. It is theoretically shown that irradiation of the short-period array antenna by a plane homogeneous terahertz waves excite a highly inhomogeneous near electric field near the metal array. In this case, the amplitude of the excited inhomogeneous near electric field is almost independent of frequency in the entire terahertz frequency range. The excitation of plasma oscillations in a two-dimensional electron system using the antenna under study is numerically simulated in the resonant and non-resonant plasmonic response modes. This type of antenna can be used for developing ultra-broadband plasmonic detectors of terahertz radiation.

  13. Time-reversed lasing in the terahertz range and its preliminary study in sensor applications

    Energy Technology Data Exchange (ETDEWEB)

    Shen, Yun, E-mail: [Department of Physics, Nanchang University, Nanchang 330031 (China); Liu, Huaqing [Department of Physics, Nanchang University, Nanchang 330031 (China); Deng, Xiaohua [Institute of Space Science and Technology, Nanchang University, Nanchang 330031 (China); Wang, Guoping [Key Laboratory of Artificial Micro- and Nano-Structures of Ministry of Education and School of Physics and Technology, Wuhan University, Wuhan 430072 (China)


    Time-reversed lasing in a uniform slab and a grating structure are investigated in the terahertz range. The results show that both the uniform slab and grating can support terahertz time-reversed lasing. Nevertheless, due to the tunable effective refractive index, the grating structure can not only exhibit time-reversed lasing more effectively and flexibly than a uniform slab, but also can realize significant absorption in a broader operating frequency range. Furthermore, applications of terahertz time-reversed lasing for novel concentration/thickness sensors are preliminarily studied in a single-channel coherent perfect absorber system. - Highlights: • Time-reversed lasing are investigated in the terahertz range. • The grating structure exhibit time-reversed lasing more effectively and flexibly than a uniform slab. • THz time-reversed lasing for novel concentration/thickness sensors are studied.

  14. A Tunable Eight-Wavelength Terahertz Modulator Based on Photonic Crystals (United States)

    Ji, K.; Chen, H.; Zhou, W.; Zhuang, Y.; Wang, J.


    We propose a tunable eight-wavelength terahertz modulator based on a structure of triple triangular lattice photonic crystals by using photonic crystals in the terahertz regime. The triple triangular lattice was formed by nesting circular, square, and triangular dielectric cylinders. Three square point defects were introduced into the perfect photonic crystal to produce eight defect modes. GaAs was used as the point defects to realize tunability. We used a structure with a reflecting barrier to achieve modulation at high transmission rate. The insertion loss and extinction ratio were 0.122 and 38.54 dB, respectively. The modulation rate was 0.788 dB. The performance of the eightwavelength terahertz modulator showed great potential for use in future terahertz communication systems.

  15. Terahertz antireflection coatings using metamaterials

    Energy Technology Data Exchange (ETDEWEB)

    Chen, Hou-tong [Los Alamos National Laboratory; Zhou, Jiangfeng [Los Alamos National Laboratory; O' Hara, John F [Los Alamos National Laboratory; Azad, Abul K [Los Alamos National Laboratory; Chen, Frank [Los Alamos National Laboratory; Taylor, Antoinette J [Los Alamos National Laboratory


    We demonstrate terahertz metamaterial antireflection coatings (ARCs) that significantly reduce the reflection and enhance the transmission at an interface of dielectric media. They are able to operate over a wide range of incidence angles for both TM and TE polarizations. Experiments and finite-element simulations will be presented and discussed.

  16. Terahertz radar cross section measurements

    DEFF Research Database (Denmark)

    Iwaszczuk, Krzysztof; Heiselberg, Henning; Jepsen, Peter Uhd


    We perform angle- and frequency-resolved radar cross section (RCS) measurements on objects at terahertz frequencies. Our RCS measurements are performed on a scale model aircraft of size 5-10 cm in polar and azimuthal configurations, and correspond closely to RCS measurements with conventional radar...

  17. A Perfect Terahertz Metamaterial Absorber


    Bagheri, Alireza; Moradi, Gholamreza


    In this paper the design for an absorbing metamaterial with near unity absorbance in terahertz region is presented. The absorber's unit cell structure consists of two metamaterial resonators that couple to electric and magnetic fields separately. The structure allows us to maximize absorption by varying dielectric material and thickness and, hence the effective electrical permittivity and magnetic permeability.

  18. Etude de la dynamique des porteurs dans des nanofils de silicium par spectroscopie terahertz (United States)

    Beaudoin, Alexandre

    Ce memoire presente une etude des proprietes de conduction electrique et de la dynamique temporelle des porteurs de charges dans des nanofils de silicium sondes par rayonnement terahertz. Les cas de nanofils de silicium non intentionnellement dopes et dopes type n sont compares pour differentes configurations du montage experimental. Les mesures de spectroscopie terahertz en transmission montre qu'il est possible de detecter la presence de dopants dans les nanofils via leur absorption du rayonnement terahertz (˜ 1--12 meV). Les difficultes de modelisation de la transmission d'une impulsion electromagnetique dans un systeme de nanofils sont egalement discutees. La detection differentielle, une modification au systeme de spectroscopie terahertz, est testee et ses performances sont comparees au montage de caracterisation standard. Les instructions et des recommendations pour la mise en place de ce type de mesure sont incluses. Les resultats d'une experience de pompe optique-sonde terahertz sont egalement presentes. Dans cette experience, les porteurs de charge temporairement crees suite a l'absorption de la pompe optique (lambda ˜ 800 nm) dans les nanofils (les photoporteurs) s'ajoutent aux porteurs initialement presents et augmentent done l'absorption du rayonnement terahertz. Premierement, l'anisotropie de l'absorption terahertz et de la pompe optique par les nanofils est demontree. Deuxiemement, le temps de recombinaison des photoporteurs est etudie en fonction du nombre de photoporteurs injectes. Une hypothese expliquant les comportements observes pour les nanofils non-dopes et dopes-n est presentee. Troisiemement, la photoconductivite est extraite pour les nanofils non-dopes et dopes-n sur une plage de 0.5 a 2 THz. Un lissage sur la photoconductivite permet d'estimer le nombre de dopants dans les nanofils dopes-n. Mots-cles: nanofil, silicium, terahertz, conductivite, spectroscopie, photoconductivite.

  19. Polymer fiber waveguides for terahertz radiation

    DEFF Research Database (Denmark)

    Nielsen, Kristian

    is taken from microstructured polymer optical fibers (mPOFs) used at optical wavelengths for sensing and communication. The fibers investigated can be divided into two groups, the solid core fibers and the hollow core fibers. The solid core fibers offer the broadest bandwidth with the best dispersion....... The polymer material with lowest loss is Topas and all the solid core fibers are manufactured using this material. The polymer PMMA however has higher refractive index along with higher loss, and this higher refractive index is utilized to achieve a large bandwidth hollow core fiber with a low air......Terahertz radiation offers many exciting applications noticeably in spectroscopy and it is showing promising results in imaging, mainly for security applications. In this project the study of using structured polymer fibers for THz waveguiding is presented. The inspiration for the THz fiber...

  20. Planar Holographic Metasurfaces for Terahertz Focusing (United States)

    Kuznetsov, Sergei A.; Astafev, Mikhail A.; Beruete, Miguel; Navarro-Cía, Miguel


    Scientists and laymen alike have always been fascinated by the ability of lenses and mirrors to control light. Now, with the advent of metamaterials and their two-dimensional counterpart metasurfaces, such components can be miniaturized and designed with additional functionalities, holding promise for system integration. To demonstrate this potential, here ultrathin reflection metasurfaces (also called metamirrors) designed for focusing terahertz radiation into a single spot and four spaced spots are proposed and experimentally investigated at the frequency of 0.35 THz. Each metasurface is designed using a computer-generated spatial distribution of the reflection phase. The phase variation within 360 deg is achieved via a topological morphing of the metasurface pattern from metallic patches to U-shaped and split-ring resonator elements, whose spectral response is derived from full-wave electromagnetic simulations. The proposed approach demonstrates a high-performance solution for creating low-cost and lightweight beam-shaping and beam-focusing devices for the terahertz band.

  1. Modeling terahertz heating effects on water. (United States)

    Kristensen, Torben T L; Withayachumnankul, Withawat; Jepsen, Peter U; Abbott, Derek


    We apply Kirchhoff's heat equation to model the influence of a CW terahertz beam on a sample of water, which is assumed to be static. We develop a generalized model, which easily can be applied to other liquids and solids by changing the material constants. If the terahertz light source is focused down to a spot with a diameter of 0.5 mm, we find that the steady-state temperature increase per milliwatt of transmitted power is 1.8?C/mW. A quantum cascade laser can produce a CW beam in the order of several milliwatts and this motivates the need to estimate the effect of beam power on the sample temperature. For THz time domain systems, we indicate how to use our model as a worst-case approximation based on the beam average power. It turns out that THz pulses created from photoconductive antennas give a negligible increase in temperature. As biotissue contains a high water content, this leads to a discussion of worst-case predictions for THz heating of the human body in order to motivate future detailed study. An open source Matlab implementation of our model is freely available for use at

  2. The development of terahertz sources and their applications. (United States)

    Davies, A G; Linfield, E H; Johnston, M B


    The terahertz region of the electromagnetic spectrum spans the frequency range between the mid-infrared and the millimetre/microwave. This region has not been exploited fully to date owing to the limited number of suitable (in particular, coherent) radiation sources and detectors. Recent demonstrations, using pulsed near-infrared femtosecond laser systems, of the viability of THz medical imaging and spectroscopy have sparked international interest; yet much research still needs to be undertaken to optimize both the power and bandwidth in such THz systems. In this paper, we review how femtosecond near-infrared laser pulses can be converted into broad band THz radiation using semiconductor crystals, and discuss in depth the optimization of one specific generation mechanism based on ultra-fast transport of electrons and holes at a semiconductor surface. We also outline a few of the opportunities for a technology that can address a diverse range of challenges spanning the physical and biological sciences, and note the continuing need for the development of solid state, continuous wave, THz sources which operate at room temperature.

  3. Remote canopy hemispherical image collection system (United States)

    Wan, Xuefen; Liu, Bingyu; Yang, Yi; Han, Fang; Cui, Jian


    Canopies are major part of plant photosynthesis and have distinct architectural elements such as tree crowns, whorls, branches, shoots, etc. By measuring canopy structural parameters, the solar radiation interception, photosynthesis effects and the spatio-temporal distribution of solar radiation under the canopy can be evaluated. Among canopy structure parameters, Leaf Area Index (LAI) is the key one. Leaf area index is a crucial variable in agronomic and environmental studies, because of its importance for estimating the amount of radiation intercepted by the canopy and the crop water requirements. The LAI can be achieved by hemispheric images which are obtained below the canopy with high accuracy and effectiveness. But existing hemispheric images canopy-LAI measurement technique is based on digital SLR camera with a fisheye lens. Users need to collect hemispheric image manually. The SLR camera with fisheye lens is not suit for long-term canopy-LAI outdoor measurement too. And the high cost of SLR limits its capacity. In recent years, with the development of embedded system and image processing technology, low cost remote canopy hemispheric image acquisition technology is becoming possible. In this paper, we present a remote hemispheric canopy image acquisition system with in-field/host configuration. In-field node based on imbed platform, low cost image sensor and fisheye lens is designed to achieve hemispherical image of plant canopy at distance with low cost. Solar radiation and temperature/humidity data, which are important for evaluating image data validation, are obtained for invalid hemispherical image elimination and node maintenance too. Host computer interacts with in-field node by 3G network. The hemispherical image calibration and super resolution are used to improve image quality in host computer. Results show that the remote canopy image collection system can make low cost remote canopy image acquisition for LAI effectively. It will be a potential

  4. Detection of terahertz radiation using submicron field effect transistors and their use for inspection applications (United States)

    Delgado Notario, J. A.; Javadi, E.; Velázquez, J. E.; Diez, E.; Meziani, Y. M.; Fobelets, K.


    We investigated room temperature detection of terahertz radiation by using two different types of transistors (Strained Silicon Modulation field effect transistor, GaAs PHEMT). Experimental results show a good level of response under excitation at 0.3 THz. Competitive performance parameters were obtained (NEP and responsivity) in comparison with other detectors. Enhancement of the photoresponse signal by imposing a dc drain-to-source current (Ids) was observed experimentally. Inspection of hidden objects by using those devices within a terahertz imaging setup was demonstrated at 300 GHz and a better image was obtained under Ids.

  5. Automated imaging system for single molecules (United States)

    Schwartz, David Charles; Runnheim, Rodney; Forrest, Daniel


    There is provided a high throughput automated single molecule image collection and processing system that requires minimal initial user input. The unique features embodied in the present disclosure allow automated collection and initial processing of optical images of single molecules and their assemblies. Correct focus may be automatically maintained while images are collected. Uneven illumination in fluorescence microscopy is accounted for, and an overall robust imaging operation is provided yielding individual images prepared for further processing in external systems. Embodiments described herein are useful in studies of any macromolecules such as DNA, RNA, peptides and proteins. The automated image collection and processing system and method of same may be implemented and deployed over a computer network, and may be ergonomically optimized to facilitate user interaction.

  6. NATO Advanced Research Workshop on Terahertz and Mid Infrared Radiation

    CERN Document Server

    Pereira, Mauro F; Terahertz and Mid Infrared Radiation


    Terahertz (THz) and Mid-Infrared (MIR) radiation  (TERA-MIR) can be transmitted through nearly any material without causing biological harm. Novel and rapid methods of detection can be created with devices operation in these spectral ranges allowing scanning for weapons, detecting hidden explosives (including plastic landmines), controlling the quality of food and a host of other exciting applications.  This book focuses on mathematical and physical aspects of the field, on unifying these two spectral domains (THz and MIR) with regard to common sources, detectors, materials and applications, and on key interdisciplinary topics. The main THz and MIR source is the quantum cascade laser (QCL). Thus significant attention is paid to the challenge of turning this advanced technology into affordable commercial devices so as to exploit its enormous potential. However other alternatives to THz QCLs are also presented, e.g.  sub-terahertz imaging from avalanching GaAs bipolar transistors, Josephson junctions as THz ...

  7. Broadband terahertz metamaterial absorber based on sectional asymmetric structures (United States)

    Gong, Cheng; Zhan, Mingzhou; Yang, Jing; Wang, Zhigang; Liu, Haitao; Zhao, Yuejin; Liu, Weiwei


    We suggest and demonstrate the concept and design of sectional asymmetric structures which can manipulate the metamaterial absorber’s working bandwidth with maintaining the other inherent advantages. As an example, a broadband terahertz perfect absorber is designed to confirm its effectiveness. The absorber’s each cell integrates four sectional asymmetric rings, and the entire structure composed of Au and Si3N4 is only 1.9 μm thick. The simulation results show the bandwidth with absorptivity being larger than 90% is extended by about 2.8 times comparing with the conventional square ring absorber. The composable small cell, ultra-thin, and broadband absorption with polarization and incident angle insensitivity will make the absorber suitable for the applications of focal plane array terahertz imaging. PMID:27571941

  8. Broadband terahertz metamaterial absorber based on sectional asymmetric structures. (United States)

    Gong, Cheng; Zhan, Mingzhou; Yang, Jing; Wang, Zhigang; Liu, Haitao; Zhao, Yuejin; Liu, Weiwei


    We suggest and demonstrate the concept and design of sectional asymmetric structures which can manipulate the metamaterial absorber's working bandwidth with maintaining the other inherent advantages. As an example, a broadband terahertz perfect absorber is designed to confirm its effectiveness. The absorber's each cell integrates four sectional asymmetric rings, and the entire structure composed of Au and Si3N4 is only 1.9 μm thick. The simulation results show the bandwidth with absorptivity being larger than 90% is extended by about 2.8 times comparing with the conventional square ring absorber. The composable small cell, ultra-thin, and broadband absorption with polarization and incident angle insensitivity will make the absorber suitable for the applications of focal plane array terahertz imaging.

  9. Development of a THz spectroscopic imaging system

    Energy Technology Data Exchange (ETDEWEB)

    Usami, M [TOCHIGI Nikon Corporation, 770 Midori, Ohtawara, Tochigi (Japan); Iwamoto, T [TOCHIGI Nikon Corporation, 770 Midori, Ohtawara, Tochigi (Japan); Fukasawa, R [TOCHIGI Nikon Corporation, 770 Midori, Ohtawara, Tochigi (Japan); Tani, M [Kansai Advanced Research Center, Communications Research Laboratory, 588-2 Iwaoka, Nishi-ku, Kobe (Japan); Watanabe, M [Kansai Advanced Research Center, Communications Research Laboratory, 588-2 Iwaoka, Nishi-ku, Kobe (Japan); Sakai, K [Kansai Advanced Research Center, Communications Research Laboratory, 588-2 Iwaoka, Nishi-ku, Kobe (Japan)


    We have developed a real-time THz imaging system based on the two-dimensional (2D) electro-optic (EO) sampling technique. Employing the 2D EO-sampling technique, we can obtain THz images using a CCD camera at a video rate of up to 30 frames per second. A spatial resolution of 1.4 mm was achieved. This resolution was reasonably close to the theoretical limit determined by diffraction. We observed not only static objects but also moving ones. To acquire spectroscopic information, time-domain images were collected. By processing these images on a computer, we can obtain spectroscopic images. Spectroscopy for silicon wafers was demonstrated.

  10. Modified pressure system for imaging egg cracks (United States)

    Lawrence, Kurt C.; Yoon, Seung Chul; Jones, Deana R.; Heitschmidt, Gerald W.; Park, Bosoon; Windham, William R.


    One aspect of grading table eggs is shell checks or cracks. Currently, USDA voluntary regulations require that humans grade a representative sample of all eggs processed. However, as processing plants and packing facilities continue to increase their volume and throughput, human graders are having difficulty matching the pace of the machines. Additionally, some plants also have a problem with micro-cracks that the graders often miss because they are very small and hard to see immediately post-processing but grow and become readily apparent before they reach market. An imaging system was developed to help the grader detect these small micro-cracks. The imaging system utilized one image captured at atmospheric pressure and a second at a slight negative pressure to enhance the crack and make detection much easier. A simple image processing algorithm was then applied to the ratio of these two images and the resulting image, containing both cracked and/or intact eggs were color-coded to simplify identification. The imaging system was capable of imaging 15 eggs in about 3/4 second and the algorithm processing took about another 10 seconds. These times could easily be reduced with a dedicated, multi-threaded computer program. In analyzing 1000 eggs, the system was 99.6% accurate overall with only 0.3% false positives compared to 94.2% accurate overall for the human graders with 1.2% false positives. An international patent on the system was filed and further automation of the system is needed.

  11. Terahertz and Mid Infrared

    CERN Document Server

    Shulika, Oleksiy; Detection of Explosives and CBRN (Using Terahertz)


    The reader will find here a timely update on new THz sources and detection schemes as well as concrete applications to the detection of Explosives and CBRN. Included is a method to identify hidden RDX-based explosives (pure and plastic ones) in the frequency domain study by Fourier Transformation, which has been complemented by the demonstration of improvement of the quality of the images captured commercially available THz passive cameras. The presented examples show large potential for the detection of small hidden objects at long distances (6-10 m).  Complementing the results in the short-wavelength range, laser spectroscopy with a mid-infrared, room temperature, continuous wave, DFB laser diode and high performance DFB QCL have been demonstrated to offer excellent enabling sensor technologies for environmental monitoring, medical diagnostics, industrial and security applications.  From the new source point of view a number of systems have been presented - From superconductors to semiconductors, e.g. Det...

  12. Challenging Aspects of Terahertz Terabit Wireless Communications

    DEFF Research Database (Denmark)

    Yu, Xianbin; Galili, Michael; Jepsen, Peter Uhd

    The increasing demand on fast wireless communications, e.g. huge data file transferring and mobile broadband access, has driven wireless communication systems into a path towards Terabit era. Terahertz (THz) technology is promising due to its unique features, such as unlimited bandwidth available...... and minimum human health threat. However, a number of technical challenges need to be overcome to achieve such an ultrafast data rate of Terabit in the THz frequency band. This presentation overview the key technologies and challenging aspects of a THz Terabit communication system, from a system point of view......, in terms of THz generation and link power budget. The THz atmospheric absorption is another critical issue to limit wireless communication range....

  13. Processing and Probability Analysis of Pulsed Terahertz NDE of Corrosion under Shuttle Tile Data (United States)

    Anastasi, Robert F.; Madaras, Eric I.; Seebo, Jeffrey P.; Ely, Thomas M.


    This paper examines data processing and probability analysis of pulsed terahertz NDE scans of corrosion defects under a Shuttle tile. Pulsed terahertz data collected from an aluminum plate with fabricated corrosion defects and covered with a Shuttle tile is presented. The corrosion defects imaged were fabricated by electrochemically etching areas of various diameter and depth in the plate. In this work, the aluminum plate echo signal is located in the terahertz time-of-flight data and a threshold is applied to produce a binary image of sample features. Feature location and area are examined and identified as corrosion through comparison with the known defect layout. The results are tabulated with hit, miss, or false call information for a probability of detection analysis that is used to identify an optimal processing threshold.

  14. Analysis of a 17C Panel Painting by Reflection Terahertz Time Domain-Imaging (THz-TDI): contribution of ultrafast optics to museum collections inspection

    DEFF Research Database (Denmark)

    Koch Dandolo, Corinna Ludovica; Filtenborg, Troels Folke; Uhd Jepsen, Peter


    THz-TDI has been applied for imaging an hidden painting and other subsurface composition layers of a 17C panel painting belonging to the National Gallery of Denmark. C- and B-scans realized by THz have been compared with images obtained by x-ray radiography, thus helping in a deep understanding o...

  15. Measuring tablet porosity using multispectral imaging system (United States)

    Nippolainen, Ervin; Ervasti, Tuomas; Ketolainen, Jarkko; Kamshilin, Alexei A.


    A multispectral imaging system with computer controlled light source of 16 light emitting diodes is applied for measuring of tablet porosity. The system is based on a subspace vector model of surface reflection. The measured spectral data are compressed on the stage of measurement and used directly for the discrimination of tablets with different porosity. The experimental results demonstrate that the multispectral imaging system is a potential method for tablet porosity measurement.

  16. Design Criteria For Networked Image Analysis System (United States)

    Reader, Cliff; Nitteberg, Alan


    Image systems design is currently undergoing a metamorphosis from the conventional computing systems of the past into a new generation of special purpose designs. This change is motivated by several factors, notably among which is the increased opportunity for high performance with low cost offered by advances in semiconductor technology. Another key issue is a maturing in understanding of problems and the applicability of digital processing techniques. These factors allow the design of cost-effective systems that are functionally dedicated to specific applications and used in a utilitarian fashion. Following an overview of the above stated issues, the paper presents a top-down approach to the design of networked image analysis systems. The requirements for such a system are presented, with orientation toward the hospital environment. The three main areas are image data base management, viewing of image data and image data processing. This is followed by a survey of the current state of the art, covering image display systems, data base techniques, communications networks and software systems control. The paper concludes with a description of the functional subystems and architectural framework for networked image analysis in a production environment.

  17. Physics and applications of terahertz radiation

    CERN Document Server

    Paul, Douglas


    This book covers the latest advances in the techniques employed to manage the THz radiation and its potential uses. It has been subdivided in three sections: THz Detectors, THz Sources, Systems and Applications. These three sections will allow the reader to be introduced in a logical way to the physics problems of sensing and generation of the terahertz radiation, the implementation of these devices into systems including other components and finally the exploitation of the equipment for real applications in some different field. All of the sections and chapters can be individually addressed in order to deepen the understanding of a single topic without the need to read the whole book. The THz Detectors section will address the latest developments in detection devices based on three different physical principles: photodetection, thermal power detection, rectification. The THz Sources section will describe three completely different generation methods, operating in three separate scales: quantum cascade lasers...

  18. Sampling system for in vivo ultrasound images

    DEFF Research Database (Denmark)

    Jensen, Jorgen Arendt; Mathorne, Jan


    Newly developed algorithms for processing medical ultrasound images use the high frequency sampled transducer signal. This paper describes demands imposed on a sampling system suitable for acquiring such data and gives details about a prototype constructed. It acquires full clinical images at a s...... at a sampling frequency of 20 MHz with a resolution of 12 bits. The prototype can be used for real time image processing. An example of a clinical in vivo image is shown and various aspects of the data acquisition process are discussed....

  19. Miniaturized Airborne Imaging Central Server System Project (United States)

    National Aeronautics and Space Administration — The innovation is a miniaturized airborne imaging central server system (MAICSS). MAICSS is designed as a high-performance computer-based electronic backend that...

  20. Miniaturized Airborne Imaging Central Server System Project (United States)

    National Aeronautics and Space Administration — The innovation is a miniaturized airborne imaging central server system (MAICSS). MAICSS is designed as a high-performance-computer-based electronic backend that...

  1. Portable EDITOR (PEDITOR): A portable image processing system. [satellite images (United States)

    Angelici, G.; Slye, R.; Ozga, M.; Ritter, P.


    The PEDITOR image processing system was created to be readily transferable from one type of computer system to another. While nearly identical in function and operation to its predecessor, EDITOR, PEDITOR employs additional techniques which greatly enhance its portability. These cover system structure and processing. In order to confirm the portability of the software system, two different types of computer systems running greatly differing operating systems were used as target machines. A DEC-20 computer running the TOPS-20 operating system and using a Pascal Compiler was utilized for initial code development. The remaining programmers used a Motorola Corporation 68000-based Forward Technology FT-3000 supermicrocomputer running the UNIX-based XENIX operating system and using the Silicon Valley Software Pascal compiler and the XENIX C compiler for their initial code development.

  2. Multiple energy synchrotron biomedical imaging system. (United States)

    Bassey, B; Martinson, M; Samadi, N; Belev, G; Karanfil, C; Qi, P; Chapman, D


    A multiple energy imaging system that can extract multiple endogenous or induced contrast materials as well as water and bone images would be ideal for imaging of biological subjects. The continuous spectrum available from synchrotron light facilities provides a nearly perfect source for multiple energy x-ray imaging. A novel multiple energy x-ray imaging system, which prepares a horizontally focused polychromatic x-ray beam, has been developed at the BioMedical Imaging and Therapy bend magnet beamline at the Canadian Light Source. The imaging system is made up of a cylindrically bent Laue single silicon (5,1,1) crystal monochromator, scanning and positioning stages for the subjects, flat panel (area) detector, and a data acquisition and control system. Depending on the crystal's bent radius, reflection type, and the horizontal beam width of the filtered synchrotron radiation (20-50 keV) used, the size and spectral energy range of the focused beam prepared varied. For example, with a bent radius of 95 cm, a (1,1,1) type reflection and a 50 mm wide beam, a 0.5 mm wide focused beam of spectral energy range 27 keV-43 keV was obtained. This spectral energy range covers the K-edges of iodine (33.17 keV), xenon (34.56 keV), cesium (35.99 keV), and barium (37.44 keV); some of these elements are used as biomedical and clinical contrast agents. Using the developed imaging system, a test subject composed of iodine, xenon, cesium, and barium along with water and bone were imaged and their projected concentrations successfully extracted. The estimated dose rate to test subjects imaged at a ring current of 200 mA is 8.7 mGy s -1 , corresponding to a cumulative dose of 1.3 Gy and a dose of 26.1 mGy per image. Potential biomedical applications of the imaging system will include projection imaging that requires any of the extracted elements as a contrast agent and multi-contrast K-edge imaging.

  3. Ultrabroadband terahertz conductivity of Si nanocrystal films

    DEFF Research Database (Denmark)

    Cooke, D. G.; Meldrum, A.; Jepsen, P. Uhd


    The terahertz conductivity of silicon nanoparticles embedded in glass with varying density is studied with ultra-broadband terahertz spectroscopy on picosecond time scales following fs optical excitation. The transition from relatively isolated charge carriers to densities which allow inter...... the applicability of this simple model to the conductivity of nanoparticle ensembles over the entire THz spectral window....

  4. Modeling terahertz heating effects on water

    DEFF Research Database (Denmark)

    Kristensen, Torben T.L.; Withayachumnankul, Withawat; Jepsen, Peter Uhd


    We apply Kirchhoff’s heat equation to model the influence of a CW terahertz beam on a sample of water, which is assumed to be static. We develop a generalized model, which easily can be applied to other liquids and solids by changing the material constants. If the terahertz light source is focused...

  5. A high throughput spectral image microscopy system (United States)

    Gesley, M.; Puri, R.


    A high throughput spectral image microscopy system is configured for rapid detection of rare cells in large populations. To overcome flow cytometry rates and use of fluorophore tags, a system architecture integrates sample mechanical handling, signal processors, and optics in a non-confocal version of light absorption and scattering spectroscopic microscopy. Spectral images with native contrast do not require the use of exogeneous stain to render cells with submicron resolution. Structure may be characterized without restriction to cell clusters of differentiation.

  6. Antenna-coupled terahertz radiation from joule-heated single-wall carbon nanotubes

    Directory of Open Access Journals (Sweden)

    M. Muthee


    Full Text Available In this letter an experimental method is introduced that allows detection of terahertz (THz radiation from arrays of joule-heated Single-Walled Carbon Nanotubes (SWCNTs, by coupling this radiation through integrated antennas and a silicon lens. The radiation forms a diffraction-limited beam with a total maximum radiated power of 450 nW, significantly greater than the power estimated from Nyquist thermal noise (8 nW. The physical radiation process is unknown at this stage, but possible explanations for the high radiated power are discussed briefly. The emission has a typical bandwidth of 1.2 THz and can be tuned to different frequencies by changing the dimensions of the antennas. Arrays of the devices could be integrated in CMOS integrated circuits, and find application in THz systems, such as in near-range medical imaging.

  7. A fractal-based image encryption system

    KAUST Repository

    Abd-El-Hafiz, S. K.


    This study introduces a novel image encryption system based on diffusion and confusion processes in which the image information is hidden inside the complex details of fractal images. A simplified encryption technique is, first, presented using a single-fractal image and statistical analysis is performed. A general encryption system utilising multiple fractal images is, then, introduced to improve the performance and increase the encryption key up to hundreds of bits. This improvement is achieved through several parameters: feedback delay, multiplexing and independent horizontal or vertical shifts. The effect of each parameter is studied separately and, then, they are combined to illustrate their influence on the encryption quality. The encryption quality is evaluated using different analysis techniques such as correlation coefficients, differential attack measures, histogram distributions, key sensitivity analysis and the National Institute of Standards and Technology (NIST) statistical test suite. The obtained results show great potential compared to other techniques.

  8. Onboard Image Processing System for Hyperspectral Sensor. (United States)

    Hihara, Hiroki; Moritani, Kotaro; Inoue, Masao; Hoshi, Yoshihiro; Iwasaki, Akira; Takada, Jun; Inada, Hitomi; Suzuki, Makoto; Seki, Taeko; Ichikawa, Satoshi; Tanii, Jun


    Onboard image processing systems for a hyperspectral sensor have been developed in order to maximize image data transmission efficiency for large volume and high speed data downlink capacity. Since more than 100 channels are required for hyperspectral sensors on Earth observation satellites, fast and small-footprint lossless image compression capability is essential for reducing the size and weight of a sensor system. A fast lossless image compression algorithm has been developed, and is implemented in the onboard correction circuitry of sensitivity and linearity of Complementary Metal Oxide Semiconductor (CMOS) sensors in order to maximize the compression ratio. The employed image compression method is based on Fast, Efficient, Lossless Image compression System (FELICS), which is a hierarchical predictive coding method with resolution scaling. To improve FELICS's performance of image decorrelation and entropy coding, we apply a two-dimensional interpolation prediction and adaptive Golomb-Rice coding. It supports progressive decompression using resolution scaling while still maintaining superior performance measured as speed and complexity. Coding efficiency and compression speed enlarge the effective capacity of signal transmission channels, which lead to reducing onboard hardware by multiplexing sensor signals into a reduced number of compression circuits. The circuitry is embedded into the data formatter of the sensor system without adding size, weight, power consumption, and fabrication cost.

  9. Image quality in digital radiographic systems

    Directory of Open Access Journals (Sweden)

    Almeida Solange Maria de


    Full Text Available The aim of the present study was to evaluate the image quality of four direct digital radiographic systems. Radiographs were made of the maxillary central incisor and mandibular left molar regions of a dry skull, and an aluminum step-wedge. The X-ray generator operated at 10 mA, 60 and 70 kVp, and images were acquired with 3, 5, 8, 12, 24 and 48 exposure pulses. Six well-trained observers classified the images by means of scores from 1 to 3. Collected data were submitted to nonparametric statistical analysis using Fisher's exact test. Statistical analysis showed significant differences (p<0.01 in image quality with the four systems. Based on the results, it was possible to conclude that: 1 all of the digital systems presented good performance in producing acceptable images for diagnosis, if the exposures of the step-wedge and the maxillary central incisor region were made at 5 pulses, as well as at 8 pulses for the mandibular left molar region, selecting 60 or 70kVp; 2 higher percentages of acceptable images were obtained with the administration of lower radiation doses in CCD-sensors (charge-coupled device; 3 the Storage Phosphor systems produced acceptable images at a large range of exposure settings, that included low, intermediate and high radiation doses.

  10. Antimonide-based pN Terahertz Mixer Diodes (United States)


    are under development including the InAs channel high electron mobility transistors , the heterojunction bipolar transistors , the resonant tunneling...spectroscopic applications . Small light-weight systems that could be hand held or carried in an airplane or satellite are highly desired. The development...not used as terahertz mixers as the junction may have a large capacitance, Cj, due to the diffusion capacitance when forward biased. The RsCj cutoff

  11. Improved Tuning Fork for Terahertz Quartz-Enhanced Photoacoustic Spectroscopy


    Sampaolo, Angelo; Patimisco, Pietro; Giglio, Marilena; Vitiello, Miriam S.; Beere, Harvey E.; Ritchie, David A.; Scamarcio, Gaetano; Tittel, Frank K.; Spagnolo, Vincenzo


    We report on a quartz-enhanced photoacoustic (QEPAS) sensor for methanol (CH3OH) detection employing a novel quartz tuning fork (QTF), specifically designed to enhance the QEPAS sensing performance in the terahertz (THz) spectral range. A discussion of the QTF properties in terms of resonance frequency, quality factor and acousto-electric transduction efficiency as a function of prong sizes and spacing between the QTF prongs is presented. The QTF was employed in a QEPAS sensor system using a ...

  12. Automatic image exploitation system for small UAVs (United States)

    Heinze, N.; Esswein, M.; Krüger, W.; Saur, G.


    For surveillance and reconnaissance tasks small UAVs are of growing importance. These UAVs have an endurance of several hours, but a small payload of about some kilograms. As a consequence lightweight sensors and cameras have to be used without having a mechanical stabilized high precision sensor-platform, which would exceed the payload and cost limitations. An example of such a system is the German UAV Luna with optical and IR sensors on board. For such platforms we developed image exploitation algorithms. The algorithms comprise mosaiking, stabilization, image enhancement, video based moving target indication, and stereo-image generation. Other products are large geo-coded image mosaics, stereo mosaics, and 3-D-model generation. For test and assessment of these algorithms the experimental system ABUL has been developed, in which the algorithms are integrated. The ABUL system is used for tests and assessment by military PIs.

  13. Visual computing scientific visualization and imaging systems

    CERN Document Server


    This volume aims to stimulate discussions on research involving the use of data and digital images as an understanding approach for analysis and visualization of phenomena and experiments. The emphasis is put not only on graphically representing data as a way of increasing its visual analysis, but also on the imaging systems which contribute greatly to the comprehension of real cases. Scientific Visualization and Imaging Systems encompass multidisciplinary areas, with applications in many knowledge fields such as Engineering, Medicine, Material Science, Physics, Geology, Geographic Information Systems, among others. This book is a selection of 13 revised and extended research papers presented in the International Conference on Advanced Computational Engineering and Experimenting -ACE-X conferences 2010 (Paris), 2011 (Algarve), 2012 (Istanbul) and 2013 (Madrid). The examples were particularly chosen from materials research, medical applications, general concepts applied in simulations and image analysis and ot...

  14. Strong terahertz field generation, detection, and application

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Ki-Yong [Univ. of Maryland, College Park, MD (United States)


    This report describes the generation and detection of high-power, broadband terahertz (THz) radiation with using femtosecond terawatt (TW) laser systems. In particular, this focuses on two-color laser mixing in gases as a scalable THz source, addressing both microscopic and macroscopic effects governing its output THz yield and radiation profile. This also includes the characterization of extremely broad THz spectra extending from microwaves to infrared frequencies. Experimentally, my group has generated high-energy (tens of microjoule), intense (>8 MV/cm), and broadband (0.01~60 THz) THz radiation in two-color laser mixing in air. Such an intense THz field can be utilized to study THz-driven extremely nonlinear phenomena in a university laboratory.

  15. Strong terahertz field generation, detection, and application

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Ki-Yong [Univ. of Maryland, College Park, MD (United States)


    This report describes the generation and detection of high-power, broadband terahertz (THz) radiation with using femtosecond terawatt (TW) laser systems. In particular, this focuses on two-color laser mixing in gases as a scalable THz source, addressing both microscopic and macroscopic effects governing its output THz yield and radiation profile. This also includes the characterization of extremely broad THz spectra extending from microwaves to infrared frequencies. Experimentally, my group has generated high-energy (tens of microjoule), intense (>8 MV/cm), and broadband (0.01~60 THz) THz radiation in two-color laser mixing in air. Such an intense THz field can be utilized to study THz-driven extremely nonlinear phenomena in a university laboratory.

  16. Terahertz Dynamics in Carbon Nanomaterials (United States)

    Kono, Junichiro


    This NSF Partnerships for International Research and Education (PIRE) project supports a unique interdisciplinary and international partnership investigating terahertz (THz) dynamics in nanostructures. The 0.1 to 10 THz frequency range of the electromagnetic spectrum is where electrical transport and optical transitions merge, offering exciting opportunities to study a variety of novel physical phenomena in condensed matter. By combining THz technology and nanotechnology, we can advance our understanding of THz physics while improving and developing THz devices. Specifically, this PIRE research explores THz dynamics of electrons in carbon nanomaterials, namely, nanotubes and graphene --- low-dimensional, sp^2-bonded carbon systems with unique finite-frequency properties. Japan and the U.S. are global leaders in both THz research and carbon research, and stimulating cooperation is critical to further advance THz science and to commercialize products developed in the lab. However, obstacles exist for international collaboration --- primarily linguistic and cultural barriers --- and this PIRE project aims to address these barriers through the integration of our research and education programs. Our strong educational portfolio endeavours to cultivate interest in nanotechnology amongst young U.S. undergraduate students and encourage them to pursue graduate study and academic research in the physical sciences, especially those from underrepresented groups. Our award-winning International Research Experience for Undergraduates Program, NanoJapan, provides structured research internships in Japanese university laboratories with Japanese mentors --- recognized as a model international education program for science and engineering students. The project builds the skill sets of nanoscience researchers and students by cultivating international and inter-cultural awareness, research expertise, and specific academic interests in nanotechnology. U.S. project partners include Rice

  17. On-Chip Terahertz-Frequency Measurements of Liquids. (United States)

    Swithenbank, Matthew; Burnett, Andrew D; Russell, Christopher; Li, Lianhe H; Davies, Alexander Giles; Linfield, Edmund H; Cunningham, John E; Wood, Christopher D


    Terahertz-frequency-range measurements can offer potential insight into the picosecond dynamics, and therefore function, of many chemical systems. There is a need to develop technologies capable of performing such measurements in aqueous and polar environments, particularly when it is necessary to maintain the full functionality of biological samples. In this study, we present a proof-of-concept technology comprising an on-chip planar Goubau line, integrated with a microfluidic channel, which is capable of low-loss, terahertz-frequency-range spectroscopic measurements of liquids. We also introduce a mathematical model that accounts for changes in the electric field distribution around the waveguide, allowing accurate, frequency-dependent liquid parameters to be extracted. We demonstrate the sensitivity of this technique by measuring a homologous alcohol series across the 0.1-0.8 THz frequency range.

  18. Design patterns in medical imaging information systems (United States)

    Hoo, Kent S., Jr.; Wong, Stephen T. C.; Laxer, Kenneth D.; Knowlton, Robert C.; Ching, Wan


    The purpose of this paper is to introduce a new and important conceptual framework of software design for the medical imaging community using design patterns. Use cases are created to summarize operational scenarios of clinicians using the system to complete certain tasks such as image segmentation. During design the Unified Modeling Language is used to translate the use cases into modeling diagrams that describe how the system functions. Next, design patterns are applied to build models that describe how software components interoperate to deliver that functionality. The software components are implemented using the Java language, CORBA architecture, and other web technologies. The biomedical image information system is used in epilepsy neurosurgical planning and diagnosis. This article proposes the use of proven software design models for solving medical imaging informatics design problems. Design patterns provide an excellent vehicle to leverage design solutions that have worked in the past to solve the problems we face in building user-friendly, reliable, and efficient information systems. This work introduces this new technology for building increasing complex medical image information systems. The rigorous application of software design techniques is essential in building information systems that are easy to use, rich in functionality, maintainable, reliable, and updatable.

  19. Anonymization server system for DICOM images (United States)

    Suzuki, H.; Amano, M.; Kubo, M.; Kawata, Y.; Niki, N.; Nishitani, H.


    We have developed an anonymization system for DICOM images. It requires consent from the patient to use the DICOM images for research or education. However, providing the DICOM image to the other facilities is not safe because it contains a lot of personal data. Our system is a server that provides anonymization service of DICOM images for users in the facility. The distinctive features of the system are, input interface, flexible anonymization policy, and automatic body part identification. In the first feature, we can use the anonymization service on the existing DICOM workstations. In the second feature, we can select a best policy fitting for the Protection of personal data that is ruled by each medical facility. In the third feature, we can identify the body parts that are included in the input image set, even if the set lacks the body part tag in DICOM header. We installed the system for the first time to a hospital in December 2005. Currently, the system is working in other four facilities. In this paper we describe the system and how it works.

  20. Image-based systems biology of infection. (United States)

    Medyukhina, Anna; Timme, Sandra; Mokhtari, Zeinab; Figge, Marc Thilo


    The successful treatment of infectious diseases requires interdisciplinary studies of all aspects of infection processes. The overarching combination of experimental research and theoretical analysis in a systems biology approach can unravel mechanisms of complex interactions between pathogens and the human immune system. Taking into account spatial information is especially important in the context of infection, since the migratory behavior and spatial interactions of cells are often decisive for the outcome of the immune response. Spatial information is provided by image and video data that are acquired in microscopy experiments and that are at the heart of an image-based systems biology approach. This review demonstrates how image-based systems biology improves our understanding of infection processes. We discuss the three main steps of this approach--imaging, quantitative characterization, and modeling--and consider the application of these steps in the context of studying infection processes. After summarizing the most relevant microscopy and image analysis approaches, we discuss ways to quantify infection processes, and address a number of modeling techniques that exploit image-derived data to simulate host-pathogen interactions in silico. © 2015 International Society for Advancement of Cytometry.


    Directory of Open Access Journals (Sweden)

    Prado-Molina, J.


    Full Text Available A low-cost airborne digital imaging system capable to perform aerial surveys with small-format cameras isintroduced. The equipment is intended to obtain high-resolution multispectral digital photographs constituting so aviable alternative to conventional aerial photography and satellite imagery. Monitoring software handles all theprocedures involved in image acquisition, including flight planning, real-time graphics for aircraft position updatingin a mobile map, and supervises the main variables engaged in the imaging process. This software also creates fileswith the geographical position of the central point of every image, and the flight path followed by the aircraftduring the entire survey. The cameras are mounted on a three-axis stabilized platform. A set of inertial sensorsdetermines platform's deviations independently from the aircraft and an automatic control system keeps thecameras at a continuous nadir pointing and heading, with a precision better than ± 1 arc-degree in three-axis. Thecontrol system is also in charge of saving the platform’s orientation angles when the monitoring software triggersthe camera. These external orientation parameters, together with a procedure for camera calibration give theessential elements for image orthocorrection. Orthomosaics are constructed using commercial GIS software.This system demonstrates the feasibility of large area coverage in a practical and economical way using smallformatcameras. Monitoring and automatization reduce the work while increasing the quality and the amount ofuseful images.

  2. Distributed-data imaging system

    Energy Technology Data Exchange (ETDEWEB)

    Tolmie, D.E.; Dornhoff, A.G.; DuBois, A.J.; Hodson, S.W.; Maestas, F.A.; Winkler, K.H.


    A group of eight Digital Equipment Corporation Alpha workstations is interconnected with ATM to form a cluster with supercomputer power. For output, each workstation drives a single tile on an 8-tile high- resolution frame buffer. A special purpose adapter is used to convert the workstation`s ATM format to the frame buffer`s HIPPI format. This paper discusses the rationale behind the workstation farm, and then describes the visualization output path in detail. To provide the system quickly, special emphasis was placed on making the design as simple as possible and using standard software protocols to drive and synchronize the display. The design choices are examined, and the resultant system is described.. Previously, a display could connect to a single computer; or a group of computers could drive a fragmented display, e.g., a video wall. Our system is unique in that it provides a high-quality desktop visualization display driven collectively by a group of workstations. A short video will be shown during the presentation to demonstrate the system capabilities.

  3. Expert System for ASIC Imaging (United States)

    Gupta, Shri N.; Arshak, Khalil I.; McDonnell, Pearse; Boyce, Conor; Duggan, Andrew


    With the developments in the techniques of artificial intelligence over the last few years, development of advisory, scheduling and similar class of problems has become very convenient using tools such as PROLOG. In this paper an expert system has been described which helps lithographers and process engineers in several ways. The methodology used is to model each work station according to its input, output and control parameters, combine these work stations in a logical sequence based on past experience and work out process schedule for a job. In addition, all the requirements vis-a-vis a particular job parameters are converted into decision rules. One example is the exposure time, develop time for a wafer with different feature sizes would be different. This expert system has been written in Turbo Prolog. By building up a large number of rules, one can tune the program to any facility and use it for as diverse applications as advisory help, trouble shooting etc. Leitner (1) has described an advisory expert system that is being used at National Semiconductor. This system is quite different from the one being reported in the present paper. The approach is quite different for one. There is stress on job flow and process for another.

  4. New terahertz dielectric spectroscopy for the study aqueous solutions

    CERN Document Server

    George, Deepu K; Vinh, N Q


    We present a development of a high precision, tunable far-infrared (terahertz) frequency-domain dielectric spectrometer for studying the dynamics of biomolecules in aqueous solutions in the gigahertz-to-terahertz frequency. As a first application we report on the measurement of the absorption and refractive index for liquid water in the frequency range from 5 GHz to 1.12 THz (0.17 to 37.36 cm-1 or 0.268 to 60 mm). The system provides a coherent radiation source with a power up to 20 mW in the gigahertz-to-terahertz region. The power signal-to-noise ratio of our instrument reaches 1015 and the system achieves a spectral resolution of less than 100 Hz. The temperature of samples can be controlled precisely with an error bars of 0.02 oC from above 0 oC to 90 oC. Given these attributes, our spectrometer provides unique capabilities for the accurate measurement of even very strongly absorbing materials such as aqueous solutions.

  5. Investigation of the Frohlich hypothesis with high intensity terahertz radiation (United States)

    Weightman, Peter


    This article provides an update to recent reviews of the Frohlich hypothesis that biological organisation is facilitated by the creation of coherent excited states driven by a flow of free energy provided by metabolic processes and mediated by molecular motions in the terahertz range. Sources of intense terahertz radiation have the potential to test this hypothesis since if it is true the growth and development of sensitive systems such as stem cells should be influenced by irradiation with intense terahertz radiation. A brief survey of recent work shows that it is not yet possible to make an assessment of the validity of the Frohlich hypothesis. Under some conditions a variety of cell types respond to irradiation with intense THz radiation in ways that involve changes in the activity of their DNA. In other experiments very intense and prolonged THz radiation has no measureable effect on the behavior of very sensitive systems such as stem cells. The wide variation in experimental conditions makes it impossible to draw any conclusions as to characteristics of THz radiation that will induce a response in living cells. It is possible that in environments suitable for their maintenance and growth cells are capable of compensating for any effects caused by exposure to THz radiation up to some currently unknown level of THz peak power.

  6. Scan image compression-encryption hardware system (United States)

    Bourbakis, Nikolaos G.; Brause, R.; Alexopoulos, C.


    This paper deals with the hardware design of an image compression/encryption scheme called SCAN. The scheme is based on the principles and ideas reflected by the specification of the SCAN language. SCAN is a fractal based context-free language which accesses sequentially the data of a 2D array, by describing and generating a wide range (near (nxn)) of space filling curves (or SCAN patterns) from a short set of simple ones. The SCAN method uses the algorithmic description of each 2D image as SCAN patterns combinations for the compression and encryption of the image data. Note that each SCAN letter or word accesses the image data with a different order (or sequence), thus the application of a variety of SCAN words associated with the compression scheme will produce various compressed versions of the same image. The compressed versions are compared in memory size and the best of them with the smallest size in bits could be used for the image compression/encryption. Note that the encryption of the image data is a result of the great number of possible space filling curves which could be generated by SCAN. Since the software implementation of the SCAN compression/encryption scheme requires some time, the hardware design and implementation of the SCAN scheme is necessary in order to reduce the image compression/encryption time to the real-time one. The development of such an image compression encryption system will have a significant impact on the transmission and storage of images. It will be applicable in multimedia and transmission of images through communication lines.

  7. Breast-Dedicated Radionuclide Imaging Systems. (United States)

    Hsu, David F C; Freese, David L; Levin, Craig S


    Breast-dedicated radionuclide imaging systems show promise for increasing clinical sensitivity for breast cancer while minimizing patient dose and cost. We present several breast-dedicated coincidence-photon and single-photon camera designs that have been described in the literature and examine their intrinsic performance, clinical relevance, and impact. Recent tracer development is mentioned, results from recent clinical tests are summarized, and potential areas for improvement are highlighted. © 2016 by the Society of Nuclear Medicine and Molecular Imaging, Inc.

  8. Biomedical Imaging in Implantable Drug Delivery Systems. (United States)

    Zhou, Haoyan; Hernandez, Christopher; Goss, Monika; Gawlik, Anna; Exner, Agata A


    Implantable drug delivery systems (DDS) provide a platform for sustained release of therapeutic agents over a period of weeks to months and sometimes years. Such strategies are typically used clinically to increase patient compliance by replacing frequent administration of drugs such as contraceptives and hormones to maintain plasma concentration within the therapeutic window. Implantable or injectable systems have also been investigated as a means of local drug administration which favors high drug concentration at a site of interest, such as a tumor, while reducing systemic drug exposure to minimize unwanted side effects. Significant advances in the field of local DDS have led to increasingly sophisticated technology with new challenges including quantification of local and systemic pharmacokinetics and implant- body interactions. Because many of these sought-after parameters are highly dependent on the tissue properties at the implantation site, and rarely represented adequately with in vitro models, new nondestructive techniques that can be used to study implants in situ are highly desirable. Versatile imaging tools can meet this need and provide quantitative data on morphological and functional aspects of implantable systems. The focus of this review article is an overview of current biomedical imaging techniques, including magnetic resonance imaging (MRI), ultrasound imaging, optical imaging, X-ray and computed tomography (CT), and their application in evaluation of implantable DDS.

  9. A computed tomographic imaging system for experimentation (United States)

    Lu, Yanping; Wang, Jue; Liu, Fenglin; Yu, Honglin


    Computed tomography (CT) is a non-invasive imaging technique, which is widely applied in medicine for diagnosis and surgical planning, and in industry for non-destructive testing (NDT) and non-destructive evaluation (NDE). So, it is significant for college students to understand the fundamental of CT. In this work, A CT imaging system named CD-50BG with 50mm field-of-view has been developed for experimental teaching at colleges. With the translate-rotate scanning mode, the system makes use of a 7.4×10 8Bq (20mCi) activity 137Cs radioactive source which is held in a tungsten alloy to shield the radiation and guarantee no harm to human body, and a single plastic scintillator + photomultitude detector which is convenient for counting because of its short-time brightness and good single pulse. At same time, an image processing software with the functions of reconstruction, image processing and 3D visualization has also been developed to process the 16 bits acquired data. The reconstruction time for a 128×128 image is less than 0.1 second. High quality images with 0.8mm spatial resolution and 2% contrast sensitivity can be obtained. So far in China, more than ten institutions of higher education, including Tsinghua University and Peking University, have already applied the system for elementary teaching.

  10. An optical imaging system for window chambers in MRI system (United States)

    Lin, Yuxiang; Salek, Mir F. S.; Jennings, Nicki; Gmitro, Arthur F.


    Window chambers are support structures implanted in the dorsal skin fold of a rodent model. Optical imaging of window chambers has been used in many basic cancer and vascular biology studies. We have recently shown that this technique can be extended to MRI by using plastic rather than metal window chambers. Here we describe a system for simultaneous optical and MR imaging of the window chambers. It provides many possibilities for independent cross validation of the measurements of one modality from the other. In the system, a GRIN lens images the tissue to the distal end of a coherent imaging fiber bundle, which relays this image to a camera system located outside the magnet room. Both trans- and epi-illumination are provided to this system. Light sources are located outside the magnet room and the light is delivered through fiber optics. A group of fibers are used to deliver white light from under the window chamber for standard transmission imaging, while another single fiber delivers the laser light from the top to induce fluorescence. An appropriate bandpass emission filter is inserted between the lenses at the camera end for fluorescence imaging. Results of simultaneously optical and MR imaging of tumor and vessel are presented.

  11. Image change detection systems, methods, and articles of manufacture (United States)

    Jones, James L.; Lassahn, Gordon D.; Lancaster, Gregory D.


    Aspects of the invention relate to image change detection systems, methods, and articles of manufacture. According to one aspect, a method of identifying differences between a plurality of images is described. The method includes loading a source image and a target image into memory of a computer, constructing source and target edge images from the source and target images to enable processing of multiband images, displaying the source and target images on a display device of the computer, aligning the source and target edge images, switching displaying of the source image and the target image on the display device, to enable identification of differences between the source image and the target image.

  12. Hardware implementation of machine vision systems: image and video processing (United States)

    Botella, Guillermo; García, Carlos; Meyer-Bäse, Uwe


    This contribution focuses on different topics covered by the special issue titled `Hardware Implementation of Machine vision Systems' including FPGAs, GPUS, embedded systems, multicore implementations for image analysis such as edge detection, segmentation, pattern recognition and object recognition/interpretation, image enhancement/restoration, image/video compression, image similarity and retrieval, satellite image processing, medical image processing, motion estimation, neuromorphic and bioinspired vision systems, video processing, image formation and physics based vision, 3D processing/coding, scene understanding, and multimedia.

  13. Handbook of terahertz technologies devices and applications

    CERN Document Server

    Song, Ho-Jin


    Terahertz waves, which lie in the frequency range of 0.1-10 THz, have long been investigated in a few limited fields, such as astronomy, because of a lack of devices for their generation and detection. Several technical breakthroughs made over the last couple of decades now allow us to radiate and detect terahertz waves more easily, which has triggered the search for new uses of terahertz waves in many fields, such as bioscience, security, and information and communications technology. The book covers some of the technical breakthroughs in terms of device technologies. It discusses not only th

  14. Quantitative performance assessments for neuromagnetic imaging systems. (United States)

    Koga, Ryo; Hiyama, Ei; Matsumoto, Takuya; Sekihara, Kensuke


    We have developed a Monte-Carlo simulation method to assess the performance of neuromagnetic imaging systems using two kinds of performance metrics: A-prime metric and spatial resolution. We compute these performance metrics for virtual sensor systems having 80, 160, 320, and 640 sensors, and discuss how the system performance is improved, depending on the number of sensors. We also compute these metrics for existing whole-head MEG systems, MEGvision™ (Yokogawa Electric Corporation, Tokyo, Japan) that uses axial-gradiometer sensors, and TRIUX™ (Elekta Corporate, Stockholm, Sweden) that uses planar-gradiometer and magnetometer sensors. We discuss performance comparisons between these significantly different systems.

  15. A hemispherical imaging and tracking (HIT) system (United States)

    Gilbert, John A.; Fair, Sara B.; Caldwell, Scott E.; Gronner, Sally J.


    A hemispherical imaging and tracking (HIT) system is described which is used for an interceptor designed to acquire, select, home, and hit-to-kill reentry vehicle targets from intercontinental ballistic missiles. The system provides a sizable field of view, over which a target may be tracked and yields a unique and distinctive optical signal when the system is 'on target'. The system has an infinite depth of focus and no moving parts are required for imaging within a hemisphere. Critical alignment of the HIT system is based on the comparison of signals captured through different points on an annular window. Assuming that the perturbations are radially symmetric, errors may be eliminated during the subtraction.

  16. Pulsed Terahertz Spectroscopy of Biomolecules (United States)

    Markelz, A. G.; Heilweil, E. J.


    Measurements of the collective vibrational modes associated with the 3D tertiary structure of biomolecules were undertaken using pulse terahertz spectroscopy. Transmission measurements of calf thymus DNA (CT-DNA), bovine serum albumin (BSA), and collagen were made for 2 cm-1 to 45 cm-1. For all three biomolecules, low frequency absorption bands could be distinguished from a broadband absorption increasing with frequency. For lyophilized powder samples, features appear at 15 cm-1 and 22 cm-1 for CT-DNA, 10 cm-1 for BSA, and 8 cm-1 and 12 cm-1 for collagen. Measurements were performed as a function of hydration and conformation.

  17. Advances in Small Animal Imaging Systems (United States)

    Loudos, George K.


    The rapid growth in genetics and molecular biology combined with the development of techniques for genetically engineering small animals has led to an increased interest in in vivo laboratory animal imaging during the past few years. For this purpose, new instrumentation, data acquisition strategies, and image processing and reconstruction techniques are being developed, researched and evaluated. The aim of this article is to give a short overview of the state of the art technologies for high resolution and high sensitivity molecular imaging techniques, primarily positron emission tomography (PET) and single photon emission computed tomography (SPECT). The basic needs of small animal imaging will be described. The evolution in instrumentation in the past two decades, as well as the commercially available systems will be overviewed. Finally, the new trends in detector technology and preliminary results from challenging applications will be presented. For more details a number of references are provided.

  18. 3D internal reconstruction by the use of terahertz time domain imaging (THz-TDI): an application on a 15th century stucco relief (United States)

    Hoi Ching, M. Cheung; Giovannacci, D.; Gariani, G.; Brissaud, D.; Leroux, L.; Goubard, F.; Bouquillon, A.; Bormand, M.


    In the field of Cultural Heritage and conservation science the development of non-invasive tools to retrieve information on artworks and historical artifacts remains one of the most important and increasing demands. In this work a focus was made on the capability of THz imaging to investigate the internal structure of objects made of superposed plaster layers. In particular, a first attempt of investigation was made for gypsum based plaster used for a stucco reliefs. After a feasibility phase on plaster moke up samples, a 15th century painted stucco relief was investigated by means of THz-TDI in the framework of the ESPRIT project, promoted by the Louvre Museum. The objectives were to assess the presence of internal layers made of different plaster mixtures, to locate them and give useful information about the supposed manufacturing techniques. The refractive indexes of different plasters were measured. Due to multiple scattering inside the samples and the impact of the heterogeneity of the material on this refractive index, the interface between plaster/plaster seems difficult to detect.

  19. Linearity of Air-Biased Coherent Detection for Terahertz Time-Domain Spectroscopy

    DEFF Research Database (Denmark)

    Wang, Tianwu; Iwaszczuk, Krzysztof; Wrisberg, Emil Astrup


    The performance of air-biased coherent detection (ABCD) in a broadband two-color laser-induced air plasma system for terahertz time-domain spectroscopy (THz-TDS) has been investigated. Fundamental parameters of the ABCD detection, including signal-to-noise ratio (SNR), dynamic range (DR), and lin......The performance of air-biased coherent detection (ABCD) in a broadband two-color laser-induced air plasma system for terahertz time-domain spectroscopy (THz-TDS) has been investigated. Fundamental parameters of the ABCD detection, including signal-to-noise ratio (SNR), dynamic range (DR...

  20. Red-sensitive imaging systems for holography (United States)

    Whitcombe, Michael James

    The primary objective of the work described in this thesis was to devise a red-sensitive photoresist imaging process for use in the replication of diffraction optics. In the introduction the chemistry of conventional photopolymer systems and photoresists used for holographic recording and the fabrication of diffraction gratings and diffracting optical elements is reviewed. The limitations of commercially available photoresist systems, particularly for applications requiring the use of red light are discussed. A polymer system has been investigated which could be imaged by photochemically generated free radicals, followed by a simple aqueous development procedure as required by the original specification. The polymer chosen for study was a copolymer of methyl methacrylate, methacrylic acid and 2-hydroxyethyl methacrylate. This was derivatized using methacryloyl chloride or methacrylic anhydride in order to introduce cross-linkable units to the polymer backbone. Polymers have been characterized by a number of techniques and the effect of varying composition on aqueous base solubility has been thoroughly studied. Various methods of derivatization have been employed. The ease of imaging has been found to be very sensitive to both the composition of the polymer and the extent of functionalization. High quality images have been obtained from this polymer using an organic solvent developer. Imaging experiments have been carried out on thin films of the photopolymer coated on glass using phenylazotriphenylmethane (PATM) as photoinitiator. Good images of 100 lines permillimetre (1 mm-1) have been recorded by contact printing. Interferometry has been used to demonstrate that interference patterns having 600 and 1200 1 mm-1 can be recorded using this polymer with PATM as initiator, exposed to an argon ion laser operating at 458nm. A number of two component photoredox initiator systems have been investigated, the light absorbing species of such systems being a dye such as

  1. Terahertz beam switching by electrical control of graphene-enabled tunable metasurface. (United States)

    Zhang, Yin; Feng, Yijun; Zhao, Junming; Jiang, Tian; Zhu, Bo


    Controlling the terahertz wave, especially the dynamical and full control of terahertz wavefront, is highly demanded due to the increasing development of practical devices and application systems. Recently considerable efforts have been made to fill the 'terahertz gap' with the help of artificial metamaterial or metasurface incorporated with graphene material. Here, we propose a scheme to design tunable metasurface consisting of metallic patch array on a grounded polymer substrate embedded with graphene layers to electrically control the electromagnetic beam reflection at terahertz frequency. By adjusting geometric dimension of the patch elements, 360 degree reflection phase range may be achieved, thus abrupt phase shifts can be introduced along the metasurface for tailoring the reflected wavefront. Moreover, the reflective phase gradient over the metasurface can be switched between 90 and 360 degree by controlling the Fermi energy of the embedded graphene through voltage biasing, hence dynamically switching the reflective beam directions. Numerical simulations demonstrate that either single beam or dual beam dynamically switching between normal and oblique reflection angles can be well attained at working frequency. The proposed approach will bring much freedom in the design of beam manipulation devices and may be applied to terahertz radiation control.

  2. High resolution multimodal clinical ophthalmic imaging system. (United States)

    Mujat, Mircea; Ferguson, R Daniel; Patel, Ankit H; Iftimia, Nicusor; Lue, Niyom; Hammer, Daniel X


    We developed a multimodal adaptive optics (AO) retinal imager which is the first to combine high performance AO-corrected scanning laser ophthalmoscopy (SLO) and swept source Fourier domain optical coherence tomography (SSOCT) imaging modes in a single compact clinical prototype platform. Such systems are becoming ever more essential to vision research and are expected to prove their clinical value for diagnosis of retinal diseases, including glaucoma, diabetic retinopathy (DR), age-related macular degeneration (AMD), and retinitis pigmentosa. The SSOCT channel operates at a wavelength of 1 microm for increased penetration and visualization of the choriocapillaris and choroid, sites of major disease activity for DR and wet AMD. This AO system is designed for use in clinical populations; a dual deformable mirror (DM) configuration allows simultaneous low- and high-order aberration correction over a large range of refractions and ocular media quality. The system also includes a wide field (33 deg.) line scanning ophthalmoscope (LSO) for initial screening, target identification, and global orientation, an integrated retinal tracker (RT) to stabilize the SLO, OCT, and LSO imaging fields in the presence of lateral eye motion, and a high-resolution LCD-based fixation target for presentation of visual cues. The system was tested in human subjects without retinal disease for performance optimization and validation. We were able to resolve and quantify cone photoreceptors across the macula to within approximately 0.5 deg (approximately 100-150 microm) of the fovea, image and delineate ten retinal layers, and penetrate to resolve features deep into the choroid. The prototype presented here is the first of a new class of powerful flexible imaging platforms that will provide clinicians and researchers with high-resolution, high performance adaptive optics imaging to help guide therapies, develop new drugs, and improve patient outcomes.

  3. Imaging Systems For Application In Harsh Environments (United States)

    Grothues, H.-G.; Michaelis, H.; Behnke, T.; Bresch, W.; Koldewey, E.; Lichopoj, A.; Tschentscher, M.; Alicke, P.

    Imaging systems operating in the wavelength domain between the near UV and the mid IR (about 300 nm to > 5 (m) play a crucial role in remote sensing from orbiters and in-situ lander measurements of planetary exploration space missions. Wide-angle and high-resolution cameras, IR imagers, and imaging spectrographs provide carto- graphic information on the morphology and topography of planetary surfaces, serve to characterize landing sites with their geological features like soils and rocks, de- liver data on the spectrophotometric characteristics of minerals, and contribute to at- mospheric reasearch. Moreover, imaging systems have the important task to present scientific missions to the general public. As resources during planetary missions are usually very limited imaging payloads have to be designed to have low mass and size, low power consumption, and to effectively handle the imaging data taking into ac- count the limited computing powers, mass memories and telemetry data rates (image data compression). Furthermore, the design has to cope with extremely harsh environ- ments such as, for example, high and very low temperatures, large temperature varia- tions and gradients, high mechanical loads (shocks), e.g. during landing on a planetary surface, a hostile particle radiation environment, and dusty or chemically aggressive atmospheres. The presentation discusses the requirements to be set up for planetary mission imaging systems, and gives an overview of the most important design mea- sures to be taken in order to be compliant with these requirements (e.g. miniatur- ization of electronics, light-weight materials, athermal and radiation tolerant design). The discussion comprises all subunits of imaging systems starting with the optics / the spectrograph and the detector unit, continuing with the data processing unit, and ending with peripheral equipment like e.g. drives, deployable booms, and illumina- tion devices for lander cameras. Examples are given of already

  4. Benchmarking image fusion system design parameters (United States)

    Howell, Christopher L.


    A clear and absolute method for discriminating between image fusion algorithm performances is presented. This method can effectively be used to assist in the design and modeling of image fusion systems. Specifically, it is postulated that quantifying human task performance using image fusion should be benchmarked to whether the fusion algorithm, at a minimum, retained the performance benefit achievable by each independent spectral band being fused. The established benchmark would then clearly represent the threshold that a fusion system should surpass to be considered beneficial to a particular task. A genetic algorithm is employed to characterize the fused system parameters using a Matlab® implementation of NVThermIP as the objective function. By setting the problem up as a mixed-integer constraint optimization problem, one can effectively look backwards through the image acquisition process: optimizing fused system parameters by minimizing the difference between modeled task difficulty measure and the benchmark task difficulty measure. The results of an identification perception experiment are presented, where human observers were asked to identify a standard set of military targets, and used to demonstrate the effectiveness of the benchmarking process.

  5. Miniaturized Airborne Imaging Central Server System (United States)

    Sun, Xiuhong


    In recent years, some remote-sensing applications require advanced airborne multi-sensor systems to provide high performance reflective and emissive spectral imaging measurement rapidly over large areas. The key or unique problem of characteristics is associated with a black box back-end system that operates a suite of cutting-edge imaging sensors to collect simultaneously the high throughput reflective and emissive spectral imaging data with precision georeference. This back-end system needs to be portable, easy-to-use, and reliable with advanced onboard processing. The innovation of the black box backend is a miniaturized airborne imaging central server system (MAICSS). MAICSS integrates a complex embedded system of systems with dedicated power and signal electronic circuits inside to serve a suite of configurable cutting-edge electro- optical (EO), long-wave infrared (LWIR), and medium-wave infrared (MWIR) cameras, a hyperspectral imaging scanner, and a GPS and inertial measurement unit (IMU) for atmospheric and surface remote sensing. Its compatible sensor packages include NASA s 1,024 1,024 pixel LWIR quantum well infrared photodetector (QWIP) imager; a 60.5 megapixel BuckEye EO camera; and a fast (e.g. 200+ scanlines/s) and wide swath-width (e.g., 1,920+ pixels) CCD/InGaAs imager-based visible/near infrared reflectance (VNIR) and shortwave infrared (SWIR) imaging spectrometer. MAICSS records continuous precision georeferenced and time-tagged multisensor throughputs to mass storage devices at a high aggregate rate, typically 60 MB/s for its LWIR/EO payload. MAICSS is a complete stand-alone imaging server instrument with an easy-to-use software package for either autonomous data collection or interactive airborne operation. Advanced multisensor data acquisition and onboard processing software features have been implemented for MAICSS. With the onboard processing for real time image development, correction, histogram-equalization, compression, georeference, and

  6. Advanced Image Understanding and Autonomous Systems


    Vernon, David


    The ultimate goal of most image understanding systems is to produce an unambiguous 3-D representation of the local visual environment. This representation can then be employed by robotic systems to effect some meaningful action. A great deal of research effort is concerned with the development of visual and 'manipulative' representations, and their generative processes, which allow for the effective linking of such visual perception and robotic action. Part of the motivation for t...

  7. A recommender system for medical imaging diagnostic. (United States)

    Monteiro, Eriksson; Valente, Frederico; Costa, Carlos; Oliveira, José Luís


    The large volume of data captured daily in healthcare institutions is opening new and great perspectives about the best ways to use it towards improving clinical practice. In this paper we present a context-based recommender system to support medical imaging diagnostic. The system relies on data mining and context-based retrieval techniques to automatically lookup for relevant information that may help physicians in the diagnostic decision.

  8. Metal Mesh Filters for Terahertz Receivers Project (United States)

    National Aeronautics and Space Administration — The technical objective of this SBIR program is to develop and demonstrate metal mesh filters for use in NASA's low noise receivers for terahertz astronomy and...

  9. Resolution limits in imaging ladar systems (United States)

    Khoury, Jed; Woods, Charles L.; Lorenzo, Joseph; Kierstead, John; Pyburn, Dana; Sengupta, Sandip K.


    We introduce a new design concept of laser radar systems that combines both phase comparison and time-of-flight methods. We show from signal-to-noise ratio considerations that there is a fundamental limit to the overall resolution in three-dimensional imaging range laser radar (ladar). We introduce a new metric, volume of resolution, and we show from quantum noise considerations that there is a maximum resolution volume that can be achieved for a given set of system parameters. Consequently, there is a direct trade-off between range resolution and spatial resolution. Thus, in a ladar system, range resolution may be maximized at the expense of spatial image resolution and vice versa. We introduce resolution efficiency etar as a new figure of merit for ladar that describes system resolution under the constraints of a specific design, compared with its optimal resolution performance derived from quantum noise considerations. We analyze how the resolution efficiency could be utilized to improve the resolution performance of a ladar system. Our analysis could be extended to all ladars, regardless of whether they are imaging or scanning laser systems.

  10. PET imaging of the autonomic nervous system. (United States)

    Thackeray, James T; Bengel, Frank M


    The autonomic nervous system is the primary extrinsic control of heart rate and contractility, and is subject to adaptive and maladaptive changes in cardiovascular disease. Consequently, noninvasive assessment of neuronal activity and function is an attractive target for molecular imaging. A myriad of targeted radiotracers have been developed over the last 25 years for imaging various components of the sympathetic and parasympathetic signal cascades. While routine clinical use remains somewhat limited, a number of larger scale studies in recent years have supplied momentum to molecular imaging of autonomic signaling. Specifically, the findings of the ADMIRE HF trial directly led to United States Food and Drug Administration approval of 123I-metaiodobenzylguanidine (MIBG) for Single Photon Emission Computed Tomography (SPECT) assessment of sympathetic neuronal innervation, and comparable results have been reported using the analogous PET agent 11C-meta-hydroxyephedrine (HED). Due to the inherent capacity for dynamic quantification and higher spatial resolution, regional analysis may be better served by PET. In addition, preliminary clinical and extensive preclinical experience has provided a broad foundation of cardiovascular applications for PET imaging of the autonomic nervous system. Recent years have witnessed the growth of novel quantification techniques, expansion of multiple tracer studies, and improved understanding of the uptake of different radiotracers, such that the transitional biology of dysfunctional subcellular catecholamine handling can be distinguished from complete denervation. As a result, sympathetic neuronal molecular imaging is poised to play a role in individualized patient care, by stratifying cardiovascular risk, visualizing underlying biology, and guiding and monitoring therapy.

  11. System for fluorescence lifetime imaging microscopy (United States)

    van Geest, Lambertus K.; Boddeke, Frank R.; van Dijk, Pieter W.; Kamp, Arjen F.; van der Oord, Cornelius J. R.; Stoop, Karel W. J.


    One of the promising recent developments in fluorescence microscopy is fluorescence lifetime imaging microscopy (FLIM). In this technique the fluorescence lifetime (ns range) of molecules is expressed in the image rather than the intensity of the light emitted by these molecules. This physical property is of interest as it gives information about the local environment of the molecule, such as molecular concentration of O2, Ca2+, pH, and conjugation. We develop an affordable, robust and easy-to-use FLIM workstation which is completely automated and does not need any difficult calibration procedure. The system consists of a standard fluorescence microscope, a modulated excitation light source, a camera, a modulation signal generator and acquisition/processing software. The camera contains an Intensified CCD of which the image intensifier gain is modulated. Depending on the application different light sources can be selected. The current light source contains a 12 mW modulated laser-diode emitting at 635 nm. A homodyne detection scheme with modulation frequencies of 1 to 100 MHz is applied, aiming at a resolution of 0.1 ns or better. High level image acquisition strategies are implemented in software, along with the low level image processing routines for lifetime estimation, calibration and correction. An evaluation of the system and its critical components will be presented in this paper.

  12. Permutation coding technique for image recognition systems. (United States)

    Kussul, Ernst M; Baidyk, Tatiana N; Wunsch, Donald C; Makeyev, Oleksandr; Martín, Anabel


    A feature extractor and neural classifier for image recognition systems are proposed. The proposed feature extractor is based on the concept of random local descriptors (RLDs). It is followed by the encoder that is based on the permutation coding technique that allows to take into account not only detected features but also the position of each feature on the image and to make the recognition process invariant to small displacements. The combination of RLDs and permutation coding permits us to obtain a sufficiently general description of the image to be recognized. The code generated by the encoder is used as an input data for the neural classifier. Different types of images were used to test the proposed image recognition system. It was tested in the handwritten digit recognition problem, the face recognition problem, and the microobject shape recognition problem. The results of testing are very promising. The error rate for the Modified National Institute of Standards and Technology (MNIST) database is 0.44% and for the Olivetti Research Laboratory (ORL) database it is 0.1%.

  13. Systematic characterization of a 1550 nm microelectromechanical (MEMS)-tunable vertical-cavity surface-emitting laser (VCSEL) with 7.92 THz tuning range for terahertz photomixing systems (United States)

    Haidar, M. T.; Preu, S.; Cesar, J.; Paul, S.; Hajo, A. S.; Neumeyr, C.; Maune, H.; Küppers, F.


    Continuous-wave (CW) terahertz (THz) photomixing requires compact, widely tunable, mode-hop-free driving lasers. We present a single-mode microelectromechanical system (MEMS)-tunable vertical-cavity surface-emitting laser (VCSEL) featuring an electrothermal tuning range of 64 nm (7.92 THz) that exceeds the tuning range of commercially available distributed-feedback laser (DFB) diodes (˜4.8 nm) by a factor of about 13. We first review the underlying theory and perform a systematic characterization of the MEMS-VCSEL, with particular focus on the parameters relevant for THz photomixing. These parameters include mode-hop-free CW tuning with a side-mode-suppression-ratio >50 dB, a linewidth as narrow as 46.1 MHz, and wavelength and polarization stability. We conclude with a demonstration of a CW THz photomixing setup by subjecting the MEMS-VCSEL to optical beating with a DFB diode driving commercial photomixers. The achievable THz bandwidth is limited only by the employed photomixers. Once improved photomixers become available, electrothermally actuated MEMS-VCSELs should allow for a tuning range covering almost the whole THz domain with a single system.

  14. Detection and Characterization of Flaws in Sprayed on Foam Insulation with Pulsed Terahertz Frequency Electromagnetic Waves (United States)

    Winfree, William P.; Madaras, Eric I.


    The detection and repair of flaws such as voids and delaminations in the sprayed on foam insulation of the external tank reduces the probability of foam debris during shuttle ascent. The low density of sprayed on foam insulation along with it other physical properties makes detection of flaws difficult with conventional techniques. An emerging technology that has application for quantitative evaluation of flaws in the foam is pulsed electromagnetic waves at terahertz frequencies. The short wavelengths of these terahertz pulses make them ideal for imaging flaws in the foam. This paper examines the application of terahertz pulses for flaw detection in foam characteristic of the foam insulation of the external tank. Of particular interest is the detection of voids and delaminations, encapsulated in the foam or at the interface between the foam and a metal backing. The technique is shown to be capable of imaging small voids and delaminations through as much as 20 cm of foam. Methods for reducing the temporal responses of the terahertz pulses to improve flaw detection and yield quantitative characterizations of the size and location of the flaws are discussed.

  15. Near real-time polarimetric imaging system. (United States)

    Buscemi, Isabella Chiara; Guyot, Steve


    A new imaging technique which enables near real-time multispectral acquisition of the so-called degree of polarization (DOP) in polarimetry using incoherent white light is described. The experimental setup allows the interactive and dynamic acquisition of DOP for all the possible elliptic polarization states. In such a way, a complete chart of light-matter interaction can be obtained and besides many structure details can be enhanced. Thus, we present the calibration and first images acquired with this system. The particular characteristics of this setup allow it to be the perfect candidate for in vivo as well as ex vivo medical applications.

  16. Live cell imaging and systems biology (United States)

    Sung, Myong-Hee; McNally, James G


    Much of the experimental data used to construct mathematical models of molecular networks are derived from in vitro measurements. However, there is increasing evidence that in vitro measurements fail to capture both the complexity and the individuality found in single, living cells. These limitations can be overcome by live cell microscopy which is evolving to enable in vivo biochemistry. Here we survey the current capabilities of live cell microscopy and illustrate how a number of different imaging approaches could be applied to analyze a specific molecular network. We argue that incorporation of such quantitative live cell imaging methods is critical for the progress of systems biology. PMID:20730797

  17. Subluminal and superluminal terahertz radiation in metamaterials with electromagnetically induced transparency. (United States)

    Bai, Zhengyang; Hang, Chao; Huang, Guoxiang


    We propose a scheme to design a new type of optical metamaterial that can mimic the functionality of four-state atomic systems of N-type energy-level configuration with electromagnetically induced transparency (EIT). We show that in such metamaterial a transition from a single EIT to a double EIT of terahertz radiation may be easily achieved by actively tuning the intensity of the infrared pump field or passively tuning the geometrical parameters of resonator structures. In addition, the group velocity of the terahertz radiation can be varied from subluminal to superluminal by changing the pump field intensity. The scheme suggested here may be used to construct chip-scale slow and fast light devices and to realize rapidly responded switching of terahertz radiation at room temperature.

  18. Web Based Distributed Coastal Image Analysis System Project (United States)

    National Aeronautics and Space Administration — This project develops Web based distributed image analysis system processing the Moderate Resolution Imaging Spectroradiometer (MODIS) data to provide decision...

  19. A Gimbal-Stabilized Compact Hyperspectral Imaging System Project (United States)

    National Aeronautics and Space Administration — The Gimbal-stabilized Compact Hyperspectral Imaging System (GCHIS) fully integrates multi-sensor spectral imaging, stereovision, GPS and inertial measurement,...

  20. System Matrix Analysis for Computed Tomography Imaging.

    Directory of Open Access Journals (Sweden)

    Liubov Flores

    Full Text Available In practical applications of computed tomography imaging (CT, it is often the case that the set of projection data is incomplete owing to the physical conditions of the data acquisition process. On the other hand, the high radiation dose imposed on patients is also undesired. These issues demand that high quality CT images can be reconstructed from limited projection data. For this reason, iterative methods of image reconstruction have become a topic of increased research interest. Several algorithms have been proposed for few-view CT. We consider that the accurate solution of the reconstruction problem also depends on the system matrix that simulates the scanning process. In this work, we analyze the application of the Siddon method to generate elements of the matrix and we present results based on real projection data.

  1. Response of asymmetric carbon nanotube network devices to sub-terahertz and terahertz radiation

    Energy Technology Data Exchange (ETDEWEB)

    Gayduchenko, I., E-mail:, E-mail: [Physics Department, Moscow State Pedagogical University, Moscow 119991 (Russian Federation); National Research Centre “Kurchatov Institute,” Moscow 123128 (Russian Federation); Kardakova, A.; Voronov, B.; Finkel, M. [Physics Department, Moscow State Pedagogical University, Moscow 119991 (Russian Federation); Fedorov, G., E-mail:, E-mail: [Physics Department, Moscow State Pedagogical University, Moscow 119991 (Russian Federation); Moscow Institute of Physics and Technology (State University), Dolgoprudny 141700 (Russian Federation); Jiménez, D. [Departament d' Enginyeria Electrònica, Escola d' Enginyeria, Universitat Autònoma de Barcelona, 08193 Bellaterra (Spain); Morozov, S. [Moscow Institute of Physics and Technology (State University), Dolgoprudny 141700 (Russian Federation); Presniakov, M. [National Research Centre “Kurchatov Institute,” Moscow 123128 (Russian Federation); Goltsman, G. [Physics Department, Moscow State Pedagogical University, Moscow 119991 (Russian Federation); Moscow Institute of Electronics and Mathematics, National Research University Higher School of Economics, Moscow 109028 (Russian Federation)


    Demand for efficient terahertz radiation detectors resulted in intensive study of the asymmetric carbon nanostructures as a possible solution for that problem. It was maintained that photothermoelectric effect under certain conditions results in strong response of such devices to terahertz radiation even at room temperature. In this work, we investigate different mechanisms underlying the response of asymmetric carbon nanotube (CNT) based devices to sub-terahertz and terahertz radiation. Our structures are formed with CNT networks instead of individual CNTs so that effects probed are more generic and not caused by peculiarities of an individual nanoscale object. We conclude that the DC voltage response observed in our structures is not only thermal in origin. So called diode-type response caused by asymmetry of the device IV characteristic turns out to be dominant at room temperature. Quantitative analysis provides further routes for the optimization of the device configuration, which may result in appearance of novel terahertz radiation detectors.

  2. Gbps terahertz external modulator based on a composite metamaterial with a double-channel heterostructure. (United States)

    Zhang, Yaxin; Qiao, Shen; Liang, Shixiong; Wu, Zhenhua; Yang, Ziqiang; Feng, Zhihong; Sun, Han; Zhou, Yucong; Sun, Linlin; Chen, Zhi; Zou, Xianbing; Zhang, Bo; Hu, Jianhao; Li, Shaoqian; Chen, Qin; Li, Ling; Xu, Gaiqi; Zhao, Yuncheng; Liu, Shenggang


    The past few decades have witnessed a substantial increase in terahertz (THz) research. Utilizing THz waves to transmit communication and imaging data has created a high demand for phase and amplitude modulation. However, current active THz devices, including modulators and switches, still cannot meet THz system demands. Double-channel heterostructures, an alternative semiconductor system, can support nanoscale two-dimensional electron gases (2DEGs) with high carrier concentration and mobility and provide a new way to develop active THz devices. In this Letter, we present a composite metamaterial structure that combines an equivalent collective dipolar array with a double-channel heterostructure to obtain an effective, ultrafast, and all-electronic grid-controlled THz modulator. Electrical control allows for resonant mode conversion between two different dipolar resonances in the active device, which significantly improves the modulation speed and depth. This THz modulator is the first to achieve a 1 GHz modulation speed and 85% modulation depth during real-time dynamic tests. Moreover, a 1.19 rad phase shift was realized. A wireless free-space-modulation THz communication system based on this external THz modulator was tested using 0.2 Gbps eye patterns. Therefore, this active composite metamaterial modulator provides a basis for the development of effective and ultrafast dynamic devices for THz wireless communication and imaging systems.

  3. Generation of high-field narrowband terahertz radiation by counterpropagating plasma wakefields (United States)

    Timofeev, I. V.; Annenkov, V. V.; Volchok, E. P.


    It is found that nonlinear interaction of plasma wakefields driven by counterpropagating laser or particle beams can efficiently generate high-power electromagnetic radiation at the second harmonic of the plasma frequency. Using a simple analytical theory and particle-in-cell simulations, we show that this phenomenon can be attractive for producing high-field ( ˜10 MV/cm) tunable terahertz radiation with a narrow line width. For laser drivers produced by existing petawatt-class systems, this nonlinear process opens the way to the generation of gigawatt, multi-millijoule terahertz pulses which are not presently available for any other generating schemes.

  4. Stratified dispersive model for material characterization using terahertz time-domain spectroscopy. (United States)

    van Mechelen, J L M; Kuzmenko, A B; Merbold, H


    We propose a novel terahertz material analysis approach that provides highly accurate material parameters and can be used for industrial quality control. The method treats the inspected material within its environment locally as a stratified system and describes the light-matter interaction of each layer in a realistic way. The approach is illustrated in the time-domain and frequency-domain for two potential fields of implementation of terahertz technology: quality control of (coated) paper sheets and car paint multilayers, both measured in humid air.

  5. High fidelity imager emulator of measured systems (United States)

    Haefner, David P.; Teaney, Brian P.


    Characterizing an imaging system through the use of linear transfer functions allows prediction of the output for an arbitrary input. Through careful measurement of the systems transfer function, imaging effects can then be applied to desired imagery in order to conduct subjective comparison, image based analysis, or evaluate algorithm performance. The Night Vision Integrated Performance Model (NV-IPM) currently utilizes a two-dimensional linear model of the systems transfer function to emulate the systems response and additive signal independent noise. In this correspondence, we describe how a two-dimensional MTF can be obtained through correct interpolation of one-dimensional measurements. We also present a model for the signal dependent noise (additive and multiplicative) and the details of its calculation from measurement. Through modeling of the experimental setup, we demonstrate how the emulated sensor replicates the observed objective performance in resolution, sampling, and noise. In support of the reproducible research effort, many of the Matlab functions associated with this work can be found on the Mathworks file exchange [1].

  6. Imaging of systemic vasculitis in childhood

    Energy Technology Data Exchange (ETDEWEB)

    Soliman, Magdy [The Hospital for Sick Children, Department of Medical Imaging, Toronto, ON (Canada); Cairo University, Department of Medical Imaging, Cairo (Egypt); Laxer, Ronald; Yeung, Rae [The Hospital for Sick Children, Department of Rheumatology, Toronto, ON (Canada); Manson, David; Doria, Andrea S. [The Hospital for Sick Children, Department of Medical Imaging, Toronto, ON (Canada)


    The term ''systemic vasculitis'' encompasses a diverse set of diseases linked by the presence of blood-vessel inflammation that are often associated with critical complications. These diseases are uncommon in childhood and are frequently subjected to a delayed diagnosis. Although the diagnosis and treatment may be similar for adult and childhood systemic vasculitides, the prevalence and classification vary according to the age group under investigation. For example, Kawasaki disease affects children while it is rarely encountered in adults. In 2006, the European League Against Rheumatism (EULAR) and the Pediatric Rheumatology European Society (PReS) proposed a classification system for childhood vasculitis adopting the system devised in the Chapel Hill Consensus Conference in 1993, which categorizes vasculitides according to the predominant size of the involved blood vessels into small, medium and large vessel diseases. Currently, medical imaging has a pivotal role in the diagnosis of vasculitis given recent developments in the imaging of blood vessels. For example, early diagnosis of coronary artery aneurysms, a serious complication of Kawasaki disease, is now possible by magnetic resonance imaging (MRI) of the heart and multidetector computed tomography (MDCT); positron emission tomography/CT (PET/CT) helps to assess active vascular inflammation in Takayasu arteritis. Our review offers a unique approach using the integration of the proposed classification criteria for common systemic childhood vasculitides with their most frequent imaging findings, along with differential diagnoses and an algorithm for diagnosis based on common findings. It should help radiologists and clinicians reach an early diagnosis, therefore facilitating the ultimate goal of proper management of affected children. (orig.)

  7. Molecular Imaging System for Monitoring Tumor Angiogenesis (United States)

    Aytac, Esra; Burcin Unlu, Mehmet


    In cancer, non-invasive imaging techniques that monitor molecular processes associated with the tumor angiogenesis could have a central role in the evaluation of novel antiangiogenic and proangiogenic therapies as well as early detection of the disease. Matrix metalloproteinases (MMP) can serve as specific biological targets for imaging of angiogenesis since expression of MMPs is required for angiogenesis and has been found to be upregulated in every type of human cancer and correlates with stage, invasive, metastatic properties and poor prognosis. However, for most cancers it is still unknown when, where and how MMPs are involved in the tumor angiogenesis [1]. Development of high-resolution, high sensitivity imaging techniques in parallel with the tumor models could prove invaluable for assessing the physical location and the time frame of MMP enzymatic acitivity. The goal of this study is to understand where, when and how MMPs are involved in the tumor angiogenesis. We will accomplish this goal by following two objectives: to develop a high sensitivity, high resolution molecular imaging system, to develop a virtual tumor simulator that can predict the physical location and the time frame of the MMP activity. In order to achieve our objectives, we will first develop a PAM system and develop a mathematical tumor model in which the quantitative data obtained from the PAM can be integrated. So, this work will develop a virtual tumor simulator and a molecular imaging system for monitoring tumor angiogenesis. 1.Kessenbrock, K., V. Plaks, and Z. Werb, MMP:regulators of the tumor microenvironment. Cell, 2010. 141(1)

  8. Calibration and characterization of spectral imaging systems (United States)

    Polder, Gerrit; van der Heijden, Gerie W.


    Spectral image sensors provide images with a large umber of contiguous spectral channels per pixel. This paper describes the calibration of spectrograph based spectral imaging systems. The relation between pixel position and measured wavelength was determined using three different wavelength calibration sources. Results indicate that for spectral calibration a source with very small peaks,such as a HgAr source, is preferred to arrow band filters. A second order polynomial model gives a better fit than a linear model for the pixel to wavelength mapping. The signal to noise ratio (SNR)is determined per wavelength. In the blue part of the spectrum,the SNR was lower than in the green and red part.This is due to a decreased quantum efficiency of the CCD,a smaller transmission coefficient of the spectrograph,as well as poor performance of the illuminant. Increasing the amount of blue light,using additional Fluorescent tube with special coating increased the SNR considerably. Furthermore, the spatial and spectral resolution of the system are determined.These can be used to choose appropriate binning factors to decrease the image size without losing information.

  9. A Broadband Metasurface-Based Terahertz Flat-Lens Array

    KAUST Repository

    Wang, Qiu


    A metasurface-based terahertz flat-lens array is proposed, comprising C-shaped split-ring resonators exhibiting locally engineerable phase discontinuities. Possessing a high numerical aperture, the planar lens array is flexible, robust, and shows excellent focusing characteristics in a broadband terahertz frequency. It could be an important step towards the development of planar terahertz focusing devices for practical applications.

  10. Plasmonic Terahertz Amplification in Graphene-Based Asymmetric Hyperbolic Metamaterial

    Directory of Open Access Journals (Sweden)

    Igor Nefedov


    Full Text Available We propose and theoretically explore terahertz amplification, based on stimulated generation of plasmons in graphene asymmetric hyperbolic metamaterials (AHMM, strongly coupled to terahertz radiation. In contrast to the terahertz amplification in resonant nanocavities, AHMM provides a wide-band THz amplification without any reflection in optically thin graphene multilayers.

  11. Enhanced terahertz emission from thin film semiconductor/metal interfaces

    NARCIS (Netherlands)

    Ramakrishnan, G.


    Terahertz light is electromagnetic radiation, similar to visible light. The photons that the terahertz light is comprised of carry a much smaller amount of energy compared to the visible light photons. Unlike visible light, terahertz light can pass through materials like plastic, cardboards, wood

  12. Tactile sensation imaging system for inclusion characterization (United States)

    Lee, Jong-Ha; Garcia-Acosta, Nathalia; Te, Kenny; Won, Chang-Hee


    Characterizing and locating sub-surface tumors will greatly enhance the detection and treatment of breast cancer. In this paper, a novel tactile sensation imaging system, that is capable of detecting and characterizing the subsurface object, was designed, implemented, and tested. A multi-layer Polydimethylsiloxane optical waveguide has been fabricated as the sensing probe. The light was illuminated below the acceptance angle to totally reflect within the flexible and transparent waveguide. When a waveguide is compressed by an external force, the contact area of the waveguide deforms and causes the light to scatter. The scattered light is captured by a high resolution camera and saved as an image. Using the salient features of the captured image, we estimated inclusion characteristics such as size, depth, and Young's modulus. To test the performance of the proposed system, we use a realistic tissue phantom with embedded stiff inclusions. The experimental results showed that the proposed system can detect inclusions and provide the relative values of inclusion's mechanical properties. Using these relative values, we can discern malignant and benign tumors.

  13. Enhanced MMW and SMMW/THz imaging system performance prediction and analysis tool for concealed weapon detection and pilotage obstacle avoidance. (United States)

    Murrill, Steven R; Franck, Charmaine C; Jacobs, Eddie L; Petkie, Douglas T; De Lucia, Frank C


    The U.S. Army Research Laboratory has continued to develop and enhance a millimeter-wave (MMW) and submillimeter-wave (SMMW)/terahertz (THz)-band imaging system performance prediction and analysis tool for both the detection and identification of concealed weaponry and for pilotage obstacle avoidance. The details of the MATLAB-based model that accounts for the effects of all critical sensor and display components, for the effects of atmospheric attenuation, concealment material attenuation, active illumination, target and background orientation, target and background thermal emission, and various imaging system architectures have been reported on in 2005, 2007, and 2011. This paper provides a comprehensive review of a newly enhanced MMW and SMMW/THz imaging system analysis and design tool that now includes an improved noise submodel for more accurate and reliable performance predictions, the capability to account for postcapture image contrast enhancement, and the capability to account for concealment material backscatter with active-illumination-based systems. Present plans for additional expansion of the model's predictive capabilities are also outlined.

  14. Terahertz-based target typing.

    Energy Technology Data Exchange (ETDEWEB)

    Lyo, Sungkwun Kenneth; Wanke, Michael Clement; Reno, John Louis; Shaner, Eric Arthur; Grine, Albert D.; Barrick, Todd A.


    The purpose of this work was to create a THz component set and understanding to aid in the rapid analysis of transient events. This includes the development of fast, tunable, THz detectors, along with filter components for use with standard detectors and accompanying models to simulate detonation signatures. The signature effort was crucial in order to know the spectral range to target for detection. Our approach for frequency agile detection was to utilize plasmons in the channel of a specially designed field-effect transistor called the grating-gate detector. Grating-gate detectors exhibit narrow-linewidth, broad spectral tunability through application of a gate bias, and no angular dependence in their photoresponse. As such, if suitable sensitivity can be attained, they are viable candidates for Terahertz multi-spectral focal plane arrays.

  15. Absorber for terahertz radiation management (United States)

    Biallas, George Herman; Apeldoorn, Cornelis; Williams, Gwyn P.; Benson, Stephen V.; Shinn, Michelle D.; Heckman, John D.


    A method and apparatus for minimizing the degradation of power in a free electron laser (FEL) generating terahertz (THz) radiation. The method includes inserting an absorber ring in the FEL beam path for absorbing any irregular THz radiation and thus minimizes the degradation of downstream optics and the resulting degradation of the FEL output power. The absorber ring includes an upstream side, a downstream side, and a plurality of wedges spaced radially around the absorber ring. The wedges form a scallop-like feature on the innermost edges of the absorber ring that acts as an apodizer, stopping diffractive focusing of the THz radiation that is not intercepted by the absorber. Spacing between the scallop-like features and the shape of the features approximates the Bartlett apodization function. The absorber ring provides a smooth intensity distribution, rather than one that is peaked on-center, thereby eliminating minor distortion downstream of the absorber.

  16. Strain Imaging Using Terahertz Waves and Metamaterials (United States)


    NOT TO BE CONSTRUED AS AN OFFICIAL DEPARTMENT OF THE ARMY POSITION UNLESS SO DESIGNATED BY OTHER AUTHORIZED DOCUMENTS. TRADE NAMES USE...uu Polarization ............................................ 7 8. 500 μm Region of Sample MM6 for ux Polarization...8 9. 500 μm Region of Sample MM6 Mueller Matrix Prediction for ux Transmission

  17. Terahertz semiconductor nonlinear optics

    DEFF Research Database (Denmark)

    Turchinovich, Dmitry; Hvam, Jørn Märcher; Hoffmann, Matthias


    In this proceedings we describe our recent results on semiconductor nonlinear optics, investigated using single-cycle THz pulses. We demonstrate the nonlinear absorption and self-phase modulation of strong-field THz pulses in doped semiconductors, using n-GaAs as a model system. The THz nonlinear......In this proceedings we describe our recent results on semiconductor nonlinear optics, investigated using single-cycle THz pulses. We demonstrate the nonlinear absorption and self-phase modulation of strong-field THz pulses in doped semiconductors, using n-GaAs as a model system. The THz...... is determined by (but not equal to) the electron momentum relaxation rate. Single cycle pulses of light, irrespective of the frequency range to which they belong, inherently have an ultrabroadband spectrum covering many octaves of frequencies. Unlike the single-cycle pulses in optical domain, the THz pulses can...... be easily sampled with sub-cycle resolution using conventional femtosecond lasers. This makes the THz pulses accessible model tools for direct observation of general nonlinear optical phenomena occurring in the single-cycle regime....

  18. THz pulsed time-domain imaging of an oil canvas painting: a case study of a painting by Pablo Picasso (United States)

    Fukunaga, Kaori; Ikari, Tomofumi; Iwai, Kikuko


    The terahertz pulsed time-domain imaging technique and near-infrared observation were applied to investigate an oil painting on canvas by Pablo Picasso. The multilayer structure is clearly observed in cross-sectional image by terahertz pulsed time-domain imaging, and particular Cubism style lines were revealed under newly painted area by near-infrared image.

  19. Systems for increasing the sensitivity of gamma-ray imagers (United States)

    Mihailescu, Lucian; Vetter, Kai M.; Chivers, Daniel H.


    Systems that increase the position resolution and granularity of double sided segmented semiconductor detectors are provided. These systems increase the imaging resolution capability of such detectors, either used as Compton cameras, or as position sensitive radiation detectors in imagers such as SPECT, PET, coded apertures, multi-pinhole imagers, or other spatial or temporal modulated imagers.

  20. A new class of electrically tunable metamaterial terahertz modulators. (United States)

    Yan, Rusen; Sensale-Rodriguez, Berardi; Liu, Lei; Jena, Debdeep; Xing, Huili Grace


    Switchable metamaterials offer unique solutions for efficiently manipulating electromagnetic waves, particularly for terahertz waves, which has been difficult since naturally occurring materials rarely respond to terahertz frequencies controllably. However, few terahertz modulators demonstrated to date exhibit simultaneously low attenuation and high modulation depth. In this letter we propose a new class of electrically-tunable terahertz metamaterial modulators employing metallic frequency-selective-surfaces (FSS) in conjunction with capacitively-tunable layers of electrons, promising near 100% modulation depth and graphene, Si, MoS(2), oxides etc, thus opening up myriad opportunities for realizing high performance switchable metamaterials over an ultra-wide terahertz frequency range.

  1. A particle image velocimetry system for microfluidics

    Energy Technology Data Exchange (ETDEWEB)

    Santiago, J.G.; Beebe, D.J.; Wereley, S.T.; Meinhart, C.D. [Department of Mechanical and Environmental Engineering, University of California, Santa Barbara, CA 93106 (United States); Adrian, R.J. [Department of Theoretical and Applied Mechanics, University of Illinois, Urbana, IL 61801 (United States)


    A micron-resolution particle image velocimetry (micro-PIV) system has been developed to measure instantaneous and ensemble-averaged flow fields in micron-scale fluidic devices. The system utilizes an epifluorescent microscope, 100-300 nm diameter seed particles, and an intensified CCD camera to record high-resolution particle-image fields. Velocity vector fields can be measured with spatial resolutions down to 6.9 x 6.9 x 1.5{mu} m. The vector fields are analyzed using a double-frame cross-correlation algorithm. In this technique, the spatial resolution and the accuracy of the velocity measurements is limited by the diffraction limit of the recording optics, noise in the particle image field, and the interaction of the fluid with the finite-sized seed particles. The stochastic influence of Brownian motion plays a significant role in the accuracy of instantaneous velocity measurements. The micro-PIV technique is applied to measure velocities in a Hele-Shaw flow around a 30{mu} m (major diameter) elliptical cylinder, with a bulk velocity of approximately 50{mu} m s{sup -1}. (orig.) With 2 figs., 10 refs.

  2. Special feature on imaging systems and techniques (United States)

    Yang, Wuqiang; Giakos, George


    The IEEE International Conference on Imaging Systems and Techniques (IST'2012) was held in Manchester, UK, on 16-17 July 2012. The participants came from 26 countries or regions: Austria, Brazil, Canada, China, Denmark, France, Germany, Greece, India, Iran, Iraq, Italy, Japan, Korea, Latvia, Malaysia, Norway, Poland, Portugal, Sweden, Switzerland, Taiwan, Tunisia, UAE, UK and USA. The technical program of the conference consisted of a series of scientific and technical sessions, exploring physical principles, engineering and applications of new imaging systems and techniques, as reflected by the diversity of the submitted papers. Following a rigorous review process, a total of 123 papers were accepted, and they were organized into 30 oral presentation sessions and a poster session. In addition, six invited keynotes were arranged. The conference not only provided the participants with a unique opportunity to exchange ideas and disseminate research outcomes but also paved a way to establish global collaboration. Following the IST'2012, a total of 55 papers, which were technically extended substantially from their versions in the conference proceeding, were submitted as regular papers to this special feature of Measurement Science and Technology . Following a rigorous reviewing process, 25 papers have been finally accepted for publication in this special feature and they are organized into three categories: (1) industrial tomography, (2) imaging systems and techniques and (3) image processing. These papers not only present the latest developments in the field of imaging systems and techniques but also offer potential solutions to existing problems. We hope that this special feature provides a good reference for researchers who are active in the field and will serve as a catalyst to trigger further research. It has been our great pleasure to be the guest editors of this special feature. We would like to thank the authors for their contributions, without which it would

  3. A dedicated neonatal brain imaging system (United States)

    Winchman, Tobias; Padormo, Francesco; Teixeira, Rui; Wurie, Julia; Sharma, Maryanne; Fox, Matthew; Hutter, Jana; Cordero‐Grande, Lucilio; Price, Anthony N.; Allsop, Joanna; Bueno‐Conde, Jose; Tusor, Nora; Arichi, Tomoki; Edwards, A. D.; Rutherford, Mary A.; Counsell, Serena J.; Hajnal, Joseph V.


    Purpose The goal of the Developing Human Connectome Project is to acquire MRI in 1000 neonates to create a dynamic map of human brain connectivity during early development. High‐quality imaging in this cohort without sedation presents a number of technical and practical challenges. Methods We designed a neonatal brain imaging system (NBIS) consisting of a dedicated 32‐channel receive array coil and a positioning device that allows placement of the infant's head deep into the coil for maximum signal‐to‐noise ratio (SNR). Disturbance to the infant was minimized by using an MRI‐compatible trolley to prepare and transport the infant and by employing a slow ramp‐up and continuation of gradient noise during scanning. Scan repeats were minimized by using a restart capability for diffusion MRI and retrospective motion correction. We measured the 1) SNR gain, 2) number of infants with a completed scan protocol, and 3) number of anatomical images with no motion artifact using NBIS compared with using an adult 32‐channel head coil. Results The NBIS has 2.4 times the SNR of the adult coil and 90% protocol completion rate. Conclusion The NBIS allows advanced neonatal brain imaging techniques to be employed in neonatal brain imaging with high protocol completion rates. Magn Reson Med 78:794–804, 2017. © 2016 The Authors Magnetic Resonance in Medicine published by Wiley Periodicals, Inc. on behalf of International Society for Magnetic Resonance in Medicine. This is an open access article under the terms of the Creative Commons Attribution‐NonCommercial‐NoDerivs License, which permits use and distribution in any medium, provided the original work is properly cited, the use is non‐commercial and no modifications or adaptations are made. PMID:27643791

  4. A dedicated neonatal brain imaging system. (United States)

    Hughes, Emer J; Winchman, Tobias; Padormo, Francesco; Teixeira, Rui; Wurie, Julia; Sharma, Maryanne; Fox, Matthew; Hutter, Jana; Cordero-Grande, Lucilio; Price, Anthony N; Allsop, Joanna; Bueno-Conde, Jose; Tusor, Nora; Arichi, Tomoki; Edwards, A D; Rutherford, Mary A; Counsell, Serena J; Hajnal, Joseph V


    The goal of the Developing Human Connectome Project is to acquire MRI in 1000 neonates to create a dynamic map of human brain connectivity during early development. High-quality imaging in this cohort without sedation presents a number of technical and practical challenges. We designed a neonatal brain imaging system (NBIS) consisting of a dedicated 32-channel receive array coil and a positioning device that allows placement of the infant's head deep into the coil for maximum signal-to-noise ratio (SNR). Disturbance to the infant was minimized by using an MRI-compatible trolley to prepare and transport the infant and by employing a slow ramp-up and continuation of gradient noise during scanning. Scan repeats were minimized by using a restart capability for diffusion MRI and retrospective motion correction. We measured the 1) SNR gain, 2) number of infants with a completed scan protocol, and 3) number of anatomical images with no motion artifact using NBIS compared with using an adult 32-channel head coil. The NBIS has 2.4 times the SNR of the adult coil and 90% protocol completion rate. The NBIS allows advanced neonatal brain imaging techniques to be employed in neonatal brain imaging with high protocol completion rates. Magn Reson Med 78:794-804, 2017. © 2016 The Authors Magnetic Resonance in Medicine published by Wiley Periodicals, Inc. on behalf of International Society for Magnetic Resonance in Medicine. This is an open access article under the terms of the Creative Commons Attribution-NonCommercial-NoDerivs License, which permits use and distribution in any medium, provided the original work is properly cited, the use is non-commercial and no modifications or adaptations are made. © 2016 The Authors Magnetic Resonance in Medicine published by Wiley Periodicals, Inc. on behalf of International Society for Magnetic Resonance in Medicine.

  5. Development of IR imaging system simulator (United States)

    Xiang, Xinglang; He, Guojing; Dong, Weike; Dong, Lu


    To overcome the disadvantages of the tradition semi-physical simulation and injection simulation equipment in the performance evaluation of the infrared imaging system (IRIS), a low-cost and reconfigurable IRIS simulator, which can simulate the realistic physical process of infrared imaging, is proposed to test and evaluate the performance of the IRIS. According to the theoretical simulation framework and the theoretical models of the IRIS, the architecture of the IRIS simulator is constructed. The 3D scenes are generated and the infrared atmospheric transmission effects are simulated using OGRE technology in real-time on the computer. The physical effects of the IRIS are classified as the signal response characteristic, modulation transfer characteristic and noise characteristic, and they are simulated on the single-board signal processing platform based on the core processor FPGA in real-time using high-speed parallel computation method.

  6. Image quality assessment and human visual system (United States)

    Gao, Xinbo; Lu, Wen; Tao, Dacheng; Li, Xuelong


    This paper summaries the state-of-the-art of image quality assessment (IQA) and human visual system (HVS). IQA provides an objective index or real value to measure the quality of the specified image. Since human beings are the ultimate receivers of visual information in practical applications, the most reliable IQA is to build a computational model to mimic the HVS. According to the properties and cognitive mechanism of the HVS, the available HVS-based IQA methods can be divided into two categories, i.e., bionics methods and engineering methods. This paper briefly introduces the basic theories and development histories of the above two kinds of HVS-based IQA methods. Finally, some promising research issues are pointed out in the end of the paper.

  7. Telepathology system for microscopic images utilizing superhigh-definition imaging system over B-ISDN (United States)

    Okumura, Akira; Furukawa, Isao; Fujii, Tatsuya; Ishimaru, Katsuhiro; Sakano, Toshikazu; Suzuki, Junji; Ono, Sadayasu; Hata, Jun-ichi; Ashihara, Tsukasa


    It has been recognized early on that digitizing medical information makes diagnostic technology more advanced and efficient. In order to convert image information, which comprises the majority of all medical information, into digital data, various technologies including those for input, processing, transmission storage, and display need to develop at roughly the same pace. To data, there have been few cases where this has been done. However, recent major advances in high-resolution image input/output, image encoding, super-fast transmission, high-capacity storage, and other technologies have intensified the drive towards digitizing and networking all medical information. This paper will show that the spread of super-high-speed networks capable of transmitting large amounts of data in a short time is indispensable for accurate medical diagnosis, and that this will make it possible to realize an integrated medical information syste. A target application for the medical image diagnosis of the Super High Definition imags being developed by the authors of this paper is telepathology, which particularly demands high-quality images. In this paper, we will study, among other things, the concrete issues crucial to building and networking a digital system and the approach to resolving such issues. We will also report on the building of our experimental system that fulfills such demands as well as discuss a pathological microscopic image transmission system with image quality that will not lower diagnostic accuracy and fast response and good operability that will not make diagnosticians feel impatient. Finally, we will discuss a test in which we remotely operated a microscope over an ATM line to prove that it is possible to capture, transmit, and display a still super-high-definition digital image with a resolution of 2,048 X 2,048 pixels in about 5 seconds.

  8. Photogalvanic effects induced by terahertz-lasers in semiconductor quantum films and applications; Terahertzlaserinduzierte photogalvanische Effekte in Halbleiter-Quantenfilmen und deren Anwendung

    Energy Technology Data Exchange (ETDEWEB)

    Weber, Wolfgang


    In this work photogalvanic effects where investigated in GaN/AlGaN heterostructures for the first time. For this purpose one of the strongest pulsed terahertz-lasers in the world was built and a computer controlled measurement system was developed. Additionally in this work an application of photogalvanic effects is presented, a pure-electric detection system, which allows to determine the polarisation state of terahertz radiation in sub-nanosecond time resolution. (orig.)

  9. Widely tunable telecom MEMS-VCSEL for terahertz photomixing. (United States)

    Haidar, Mohammad Tanvir; Preu, Sascha; Paul, Sujoy; Gierl, Christian; Cesar, Julijan; Emsia, Ali; Küppers, Franko


    We report frequency-tunable terahertz (THz) generation with a photomixer driven by an ultra-broadband tunable micro-electro-mechanical system vertical-cavity surface-emitting laser (MEMS-VCSEL) and a fixed-wavelength VCSEL, as well as a tunable MEMS-VCSEL mixed with a distributed feedback (DFB) diode. A total frequency span of 3.4 THz is covered in direct detection mode and 3.23 THz in the homodyne mode. The tuning range is solely limited by the dynamic range of the photomixers and the Schottky diode/photoconductor used in the experiment.

  10. Projection image enhancement for explosive detection systems (United States)

    Yildiz, Yesna O.; Abraham, Douglas Q.; Agaian, Sos; Panetta, Karen


    Automated Explosive Detection Systems (EDS) utilizing Computed Tomography (CT) generate a series of 2-D projections from a series of X-ray scans OF luggage under inspection. 3-D volumetric images can also be generated from the collected data set. Extensive data manipulation of the 2-D and 3-D image sets for detecting the presence of explosives is done automatically by EDS. The results are then forwarded to human screeners for final review. The final determination as to whether the luggage contains an explosive and needs to be searched manually is performed by trained TSA (Transportation Security Administration) screeners following an approved TSA protocol. The TSA protocol has the screeners visually inspect the resulting images and the renderings from the EDS to determine if the luggage is suspicious and consequently should be searched manually. Enhancing those projection images delivers a higher quality screening, reduces screening time and also reduces the amount of luggage that needs to be manually searched otherwise. This paper presents a novel edge detection algorithm that is geared towards, though not exclusive to, automated explosive detection systems. The goal of these enhancements is to provide a higher quality screening process while reducing the overall screening time and luggage search rates. Accurately determining the location of edge pixels within 2-D signals, often the first step in segmentation and recognition systems indicates the boundary between overlapping objects in a luggage. Most of the edge detection algorithms such as Canny, Prewitt, Roberts, Sobel, and Laplacian methods are based on the first and second derivatives/difference operators. These operators detect the discontinuities in the differences of pixels. These approaches are sensitive to the presence of noise and could produce false edges in noisy images. Including large scale filters, may avoid errors generated by noise, but often simultaneously eliminating the finer edge details as

  11. Intelligent elevator management system using image processing (United States)

    Narayanan, H. Sai; Karunamurthy, Vignesh; Kumar, R. Barath


    In the modern era, the increase in the number of shopping malls and industrial building has led to an exponential increase in the usage of elevator systems. Thus there is an increased need for an effective control system to manage the elevator system. This paper is aimed at introducing an effective method to control the movement of the elevators by considering various cases where in the location of the person is found and the elevators are controlled based on various conditions like Load, proximity etc... This method continuously monitors the weight limit of each elevator while also making use of image processing to determine the number of persons waiting for an elevator in respective floors. Canny edge detection technique is used to find out the number of persons waiting for an elevator. Hence the algorithm takes a lot of cases into account and locates the correct elevator to service the respective persons waiting in different floors.

  12. Calibrations for a MCAO Imaging System (United States)

    Hibon, Pascale; B. Neichel; V. Garrel; R. Carrasco


    "GeMS, the Gemini Multi conjugate adaptive optics System installed at the Gemini South telescope (Cerro Pachon, Chile) started to deliver science since the beginning of 2013. GeMS is using the Multi Conjugate AdaptiveOptics (MCAO) technique allowing to dramatically increase the corrected field of view (FOV) compared to classical Single Conjugated Adaptive Optics (SCAO) systems. It is the first sodium-based multi-Laser Guide Star (LGS) adaptive optics system. It has been designed to feed two science instruments: GSAOI, a 4k×4k NIR imager covering 85"×85" with 0.02" pixel scale, and Flamingos-2, a NIR multi-object spectrograph. We present here an overview of the calibrations necessary for reducing and analysing the science datasets obtained with GeMS+GSAOI."

  13. Commercial perspective in THz spectroscopy, sensing and imaging (Conference Presentation) (United States)

    Bouyé, Clémentine; Taoudi, Sarah; Cochard, Jacques; d'Humières, Benoît


    For their ability to be transmitted by materials opaque in the visible and IR ranges (clothes, plastic, …), for being non-ionizing, for providing sub-mm resolution imaging, for the specific signatures of numerous materials, Terahertz waves - ranging from 200 GHz to 10 THz - have been raising the interest of industrials for about fifteen years. This study focuses on the penetration of THz technologies into the industrial applications driving the THz market growth at short and long term: Non Destructive testing (NDT), Defense and Security, Biomedical. For 15 years, Terahertz technologies have been continuously tested on a wide variety of applications. Thanks to these ongoing feasibility studies, manufacturers and end-users gained a deeper knowledge about the abilities and the limitations of the different Terahertz systems (Time-Domain spectroscopy, Frequency-Domain spectroscopy, Time-Domain reflectometry, etc). The demand from end-users is more qualified and is segmented as follows: 1. Detection of objects and defects on large areas 2. Thickness measurement on large areas 3. Chemical and Structural characterization of small objects and defects on small areas (2D) or volumes (3D) Each of these 3 functions leads to a specific family of THz systems with distinct requirements in terms of performance and cost: 1. Detection: cheap and compact imaging systems. 2. Thickness measurement: cost-effective and high speed systems. 3. Characterization: high resolution, high reliability and real-time sensing systems. This article will present the existing and incoming THz systems and components addressing each function. Terahertz technologies are currently finding their place on the market, outside research and scientific applications. The objective of this article is to identify the industrial applications where THz techniques will be adopted and to provide market growth perspectives.

  14. Time-resolved single-shot terahertz time-domain spectroscopy for ultrafast irreversible processes (United States)

    Zhai, Zhao-Hui; Zhong, Sen-Cheng; Li, Jun; Zhu, Li-Guo; Meng, Kun; Li, Jiang; Liu, Qiao; Peng, Qi-Xian; Li, Ze-Ren; Zhao, Jian-Heng


    Pulsed terahertz spectroscopy is suitable for spectroscopic diagnostics of ultrafast events. However, the study of irreversible or single shot ultrafast events requires ability to record transient properties at multiple time delays, i.e., time resolved at single shot level, which is not available currently. Here by angular multiplexing use of femtosecond laser pulses, we developed and demonstrated a time resolved, transient terahertz time domain spectroscopy technique, where burst mode THz pulses were generated and then detected in a single shot measurement manner. The burst mode THz pulses contain 2 sub-THz pulses, and the time gap between them is adjustable up to 1 ns with picosecond accuracy, thus it can be used to probe the single shot event at two different time delays. The system can detect the sub-THz pulses at 0.1 THz-2.5 THz range with signal to noise ratio (SNR) of ˜400 and spectrum resolution of 0.05 THz. System design was described here, and optimizations of single shot measurement of THz pulses were discussed in detail. Methods to improve SNR were also discussed in detail. A system application was demonstrated where pulsed THz signals at different time delays of the ultrafast process were successfully acquired within single shot measurement. This time resolved transient terahertz time domain spectroscopy technique provides a new diagnostic tool for irreversible or single shot ultrafast events where dynamic information can be extracted at terahertz range within one-shot experiment.

  15. Multispectral imaging system for contaminant detection (United States)

    Poole, Gavin H. (Inventor)


    An automated inspection system for detecting digestive contaminants on food items as they are being processed for consumption includes a conveyor for transporting the food items, a light sealed enclosure which surrounds a portion of the conveyor, with a light source and a multispectral or hyperspectral digital imaging camera disposed within the enclosure. Operation of the conveyor, light source and camera are controlled by a central computer unit. Light reflected by the food items within the enclosure is detected in predetermined wavelength bands, and detected intensity values are analyzed to detect the presence of digestive contamination.

  16. Near-field probing of Mie resonances in single TiO.sub.2./sub. microspheres at terahertz frequencies

    Czech Academy of Sciences Publication Activity Database

    Mitrofanov, O.; Dominec, Filip; Kužel, Petr; Reno, J.L.; Brener, I.; Chung, U.-C.; Elissalde, C.; Maglione, M.; Mounaix, P.


    Roč. 22, č. 19 (2014), s. 23034-23042 ISSN 1094-4087 R&D Projects: GA ČR(CZ) GA14-25639S EU Projects: European Commission(XE) 607521 - NOTEDEV Institutional support: RVO:68378271 Keywords : metamaterials * near-field microscopy * resonators * terahertz imaging Subject RIV: BH - Optics, Masers, Lasers Impact factor: 3.488, year: 2014

  17. Neutron imaging for geothermal energy systems

    Energy Technology Data Exchange (ETDEWEB)

    Bingham, Philip R [ORNL; Anovitz, Lawrence {Larry} M [ORNL; Polsky, Yarom [ORNL


    Geothermal systems extract heat energy from the interior of the earth using a working fluid, typically water. Three components are required for a commercially viable geothermal system: heat, fluid, and permeability. Current commercial electricity production using geothermal energy occurs where the three main components exist naturally. These are called hydrothermal systems. In the US, there is an estimated 30 GW of base load electrical power potential for hydrothermal sites. Next generation geothermal systems, named Enhanced Geothermal Systems (EGS), have an estimated potential of 4500 GW. EGSs lack in-situ fluid, permeability or both. As such, the heat exchange system must be developed or engineered within the rock. The envisioned method for producing permeability in the EGS reservoir is hydraulic fracturing, which is rarely practiced in the geothermal industry, and not well understood for the rocks typically present in geothermal reservoirs. High costs associated with trial and error learning in the field have led to an effort to characterize fluid flow and fracturing mechanisms in the laboratory to better understand how to design and manage EGS reservoirs. Neutron radiography has been investigated for potential use in this characterization. An environmental chamber has been developed that is suitable for reproduction of EGS pressures and temperatures and has been tested for both flow and precipitations studies with success for air/liquid interface imaging and 3D reconstruction of precipitation within the core.

  18. Laser induced fluorescence imaging system for localization of nasopharyngeal carcinoma (United States)

    Liu, Lina; Xie, Shusen


    A laser induced fluorescence imaging system for localization of Nasopharyngeal Carcinoma is developed. In this fluorescence imaging system, the fluorescence intensity with information of detected objection is gained by an image intensifier, which makes color information of the fluorescence image eliminated and the result is a monochrome image of the fluorescence with thermally induced noise. The monochrome fluorescence image is sent to a CCD and captured by an image board, which is controlled by a computer. Image processing is carried out to improve the image quality and therefore improve the system's ability to differentiate carcinomas from normal tissue. Gaussian smoothing is implemented in order to reduce the noise. Image binarizing process is realized to obtain an optimal threshold of the image. Image pixels with grey value below this threshold are assigned as diseased and those above are normal. A pseudo color processing is then accomplished to get better visual perception and understanding of the image, greatly increasing the detail resolution of the grey image. The processed image is then displayed on the screen of the computer in real time. The real time laser induced fluorescence imaging system with the image processing methods developed is efficient for localization of the nasopharyngeal carcinoma.

  19. Terahertz-frequency dielectric response of liquids

    DEFF Research Database (Denmark)

    Jepsen, Peter Uhd; Møller, Uffe; Cooke, David

    -induced dipole moments. In the polar liquid water the fastest relaxational dynamics is found at terahertz frequencies, just below the first intermolecular vibrational and librational modes. In this presentation we will discuss optical terahertz spectroscopic techniques for measurement of the full dielectric...... function of liquids at terahertz frequencies. We will review the current understanding of the high-frequency dielectric spectrum of water, and discuss the relation between the dielectric spectrum and the thermodynamic properties of certain aqueous solutions.......The dielectric response of liquids spans many decades in frequency. The dielectric response of a polar liquid is typically determined by relaxational dynamics of the dipolar moments of the liquid. In contrast, the dielectric response of a nonpolar liquid is determined by much weaker collision...

  20. Robust Topological Terahertz Circuits using Semiconductors

    CERN Document Server

    Bahari, Babak; Kanté, Boubacar


    Topological Insulator-based devices can transport electrons/photons at the surfaces of materials without any back reflections, even in the presence of obstacles. Topological properties have recently been studied using non-reciprocal materials such as gyromagnetics or using bianisotropy. However, these effects usually saturate at optical frequencies and limit our ability to scale down devices. In order to implement topological devices that we introduce in this paper for the terahertz range, we show that semiconductors can be utilized via their cyclotron resonance in combination with small magnetic fields. We propose novel terahertz operating devices such as the topological tunable power splitter and the topological circulator. This work opens new perspectives in the design of terahertz integrated devices and circuits with high functionality.

  1. Micromachined components for terahertz frequency applications

    CERN Document Server

    Parkhurst, G M


    lithographic technology for the fabrication of terahertz circuits, the integration of an active solid state device is explored. The device chosen for this work is the resonant tunnel diode (RTD). Some background discussion of the operation of these devices as oscillators is presented, and techniques for full integration of devices into a waveguide, using processes which are completely compatible with semiconductor manufacturing technology, are explored experimentally. Two main problems prevent the use of the terahertz frequency band (defined for present purposes as 100GHz - 10THz) in a wider range of applications. The first is the absence of a convenient, cheap solid-state source of power and the second is the significant cost of conventional passive components. In this Thesis, the second issue is addressed in detail, describing developments in the fabrication and characterisation of low cost lithographically-produced terahertz frequency passive components. An extensive study of the use of ultra-thick UV phot...

  2. Complex extreme learning machine applications in terahertz pulsed signals feature sets. (United States)

    Yin, X-X; Hadjiloucas, S; Zhang, Y


    This paper presents a novel approach to the automatic classification of very large data sets composed of terahertz pulse transient signals, highlighting their potential use in biochemical, biomedical, pharmaceutical and security applications. Two different types of THz spectra are considered in the classification process. Firstly a binary classification study of poly-A and poly-C ribonucleic acid samples is performed. This is then contrasted with a difficult multi-class classification problem of spectra from six different powder samples that although have fairly indistinguishable features in the optical spectrum, they also possess a few discernable spectral features in the terahertz part of the spectrum. Classification is performed using a complex-valued extreme learning machine algorithm that takes into account features in both the amplitude as well as the phase of the recorded spectra. Classification speed and accuracy are contrasted with that achieved using a support vector machine classifier. The study systematically compares the classifier performance achieved after adopting different Gaussian kernels when separating amplitude and phase signatures. The two signatures are presented as feature vectors for both training and testing purposes. The study confirms the utility of complex-valued extreme learning machine algorithms for classification of the very large data sets generated with current terahertz imaging spectrometers. The classifier can take into consideration heterogeneous layers within an object as would be required within a tomographic setting and is sufficiently robust to detect patterns hidden inside noisy terahertz data sets. The proposed study opens up the opportunity for the establishment of complex-valued extreme learning machine algorithms as new chemometric tools that will assist the wider proliferation of terahertz sensing technology for chemical sensing, quality control, security screening and clinic diagnosis. Furthermore, the proposed

  3. QI2S - Quick Image Interpretation System (United States)

    Naghmouchi, Jamin; Aviely, Peleg; Ginosar, Ran; Ober, Giovanna; Bischoff, Ole; Nadler, Ron; Guiser, David; Citroen, Meira; Freddi, Riccardo; Berekovic, Mladen


    The evolution of the Earth Observation mission will be driven by many factors, and the deveploment of new processing paradigms to facilitate data downlink, handling and storage will be a key factor. Next generation EO satellites will generate a great amount of data at a very high data rate, both radar and optical. Real-time onboard processing can be the solution to reduce data downlink and management on ground. Radiometric, geometric, and atmospheric corrections of EO data as well as material/object detection in addition to the well-known needs for image compression and signal processing can be performed directly on board and the aim of QI2S project is to demonstrate this. QI2S, a concept prototype system for novel onboard image processing and image interpretation which has been designed, developed and validated in the framework of an EU FP7 project, targets these needs and makes a significant step towards exceeding current roadmaps of leading space agencies for future payload processors. The QI2S system features multiple chip components of the RC64, a novel rad-hard 64-core signal processing chip, which targets DSP performance of 75 GMACs (16bit), 150 GOPS and 38 single precision GFLOPS while dissipating less than 10 Watts. It integrates advanced DSP cores with a multibank shared memory and a hardware scheduler, also supporting DDR2/3 memory and twelve 3.125 Gbps full duplex high-speed serial links using SpaceFibre and other protocols. The processor is being developed within the European FP7 Framework Program and will be qualified to the highest space standards.

  4. Novel compact photoacoustic imaging system to explore the applications in the medical imaging field (United States)

    Irisawa, Kaku; Wada, Takatsugu; Hayakawa, Toshiro; Ishihara, Miya


    PhotoAcoustic (PA) imaging is a promising imaging method using the pulsed-laser light source and ultrasound detector. PA image shows the features of optical contrast in biological tissue with ultrasound-like depth and resolution. In the human body, Hemoglobin of the blood is strong optical absorber, so the high-contrast blood distribution (vascular) image is obtained by PA imaging. Recently, FUJIFILM has developed the PA imaging system to explore its application in medical imaging field. In this system, the fusion of PA and conventional ultrasound image is realized, for example, ultrasound Doppler image is superposed to the PA and B-mode image. The system features and some results of clinical studies will be introduced.

  5. APPLEPIPS /Apple Personal Image Processing System/ - An interactive digital image processing system for the Apple II microcomputer (United States)

    Masuoka, E.; Rose, J.; Quattromani, M.


    Recent developments related to microprocessor-based personal computers have made low-cost digital image processing systems a reality. Image analysis systems built around these microcomputers provide color image displays for images as large as 256 by 240 pixels in sixteen colors. Descriptive statistics can be computed for portions of an image, and supervised image classification can be obtained. The systems support Basic, Fortran, Pascal, and assembler language. A description is provided of a system which is representative of the new microprocessor-based image processing systems currently on the market. While small systems may never be truly independent of larger mainframes, because they lack 9-track tape drives, the independent processing power of the microcomputers will help alleviate some of the turn-around time problems associated with image analysis and display on the larger multiuser systems.

  6. Tunable Terahertz Hybrid Metal-Graphene Plasmons. (United States)

    Jadidi, Mohammad M; Sushkov, Andrei B; Myers-Ward, Rachael L; Boyd, Anthony K; Daniels, Kevin M; Gaskill, D Kurt; Fuhrer, Michael S; Drew, H Dennis; Murphy, Thomas E


    We report here a new type of plasmon resonance that occurs when graphene is connected to a metal. These new plasmon modes offer the potential to incorporate a tunable plasmonic channel into a device with electrical contacts, a critical step toward practical graphene terahertz optoelectronics. Through theory and experiments, we demonstrate, for example, anomalously high resonant absorption or transmission when subwavelength graphene-filled apertures are introduced into an otherwise conductive layer. These tunable plasmon resonances are essential yet missing ingredients needed for terahertz filters, oscillators, detectors, and modulators.

  7. Three-dimensional broadband tunable terahertz metamaterials

    DEFF Research Database (Denmark)

    Fan, Kebin; Strikwerda, Andrew; Zhang, Xin


    We present optically tunable magnetic three-dimensional (3D) metamaterials at terahertz (THz) frequencies which exhibit a tuning range of ~30% of the resonance frequency. This is accomplished by fabricating 3D array structures consisting of double-split-ring resonators (DSRRs) on silicon on sapph......We present optically tunable magnetic three-dimensional (3D) metamaterials at terahertz (THz) frequencies which exhibit a tuning range of ~30% of the resonance frequency. This is accomplished by fabricating 3D array structures consisting of double-split-ring resonators (DSRRs) on silicon...

  8. Dynamic optically induced planar terahertz quasioptics

    DEFF Research Database (Denmark)

    Cooke, David; Jepsen, Peter Uhd


    Optical control of the propagation direction of a terahertz pulse inside an optically transparent parallel plate waveguide is demonstrated by patterned charge carrier photoexcitation of a silicon slab embedded within the waveguide. It is shown experimentally and through finite element simulations...... that photoexcitations with sufficient conductivity can induce a partial reflection, capable of steering the pulse inside the two-dimensional waveguide. A beamsplitter is demonstrated as proof of principle and is used to delay the arrival of the reflected terahertz pulse at the detector by several picoseconds by moving...

  9. [A novel image processing and analysis system for medical images based on IDL language]. (United States)

    Tang, Min


    Medical image processing and analysis system, which is of great value in medical research and clinical diagnosis, has been a focal field in recent years. Interactive data language (IDL) has a vast library of built-in math, statistics, image analysis and information processing routines, therefore, it has become an ideal software for interactive analysis and visualization of two-dimensional and three-dimensional scientific datasets. The methodology is proposed to design a novel image processing and analysis system for medical images based on IDL. There are five functional modules in this system: Image Preprocessing, Image Segmentation, Image Reconstruction, Image Measurement and Image Management. Experimental results demonstrate that this system is effective and efficient, and it has the advantages of extensive applicability, friendly interaction, convenient extension and favorable transplantation.

  10. Carbon nanotube fiber terahertz polarizer (United States)

    Zubair, Ahmed; Tsentalovich, Dmitri E.; Young, Colin C.; Heimbeck, Martin S.; Everitt, Henry O.; Pasquali, Matteo; Kono, Junichiro


    Conventional, commercially available terahertz (THz) polarizers are made of uniformly and precisely spaced metallic wires. They are fragile and expensive, with performance characteristics highly reliant on wire diameters and spacings. Here, we report a simple and highly error-tolerant method for fabricating a freestanding THz polarizer with nearly ideal performance, reliant on the intrinsically one-dimensional character of conduction electrons in well-aligned carbon nanotubes (CNTs). The polarizer was constructed on a mechanical frame over which we manually wound acid-doped CNT fibers with ultrahigh electrical conductivity. We demonstrated that the polarizer has an extinction ratio of ˜-30 dB with a low insertion loss (fiber polarizer and found comparable attenuation to a commercial metallic wire-grid polarizer. Furthermore, based on the classical theory of light transmission through an array of metallic wires, we demonstrated the most striking difference between the CNT-fiber and metallic wire-grid polarizers: the latter fails to work in the zero-spacing limit, where it acts as a simple mirror, while the former continues to work as an excellent polarizer even in that limit due to the one-dimensional conductivity of individual CNTs.

  11. Carbon nanotube fiber terahertz polarizer

    Energy Technology Data Exchange (ETDEWEB)

    Zubair, Ahmed [Department of Electrical and Computer Engineering, Rice University, Houston, Texas 77005 (United States); Tsentalovich, Dmitri E.; Young, Colin C. [Department of Chemical and Biomolecular Engineering, Rice University, Houston, Texas 77005 (United States); Heimbeck, Martin S. [Charles M. Bowden Laboratory, Aviation & Missile Research, Development, and Engineering Center (AMRDEC), Redstone Arsenal, Alabama 35898 (United States); Everitt, Henry O. [Department of Electrical and Computer Engineering, Rice University, Houston, Texas 77005 (United States); Charles M. Bowden Laboratory, Aviation & Missile Research, Development, and Engineering Center (AMRDEC), Redstone Arsenal, Alabama 35898 (United States); Pasquali, Matteo [Department of Chemical and Biomolecular Engineering, Rice University, Houston, Texas 77005 (United States); Department of Chemistry, Rice University, Houston, Texas 77005 (United States); Department of Materials Science and NanoEngineering, Rice University, Houston, Texas 77005 (United States); Kono, Junichiro, E-mail: [Department of Electrical and Computer Engineering, Rice University, Houston, Texas 77005 (United States); Department of Materials Science and NanoEngineering, Rice University, Houston, Texas 77005 (United States); Department of Physics and Astronomy, Rice University, Houston, Texas 77005 (United States)


    Conventional, commercially available terahertz (THz) polarizers are made of uniformly and precisely spaced metallic wires. They are fragile and expensive, with performance characteristics highly reliant on wire diameters and spacings. Here, we report a simple and highly error-tolerant method for fabricating a freestanding THz polarizer with nearly ideal performance, reliant on the intrinsically one-dimensional character of conduction electrons in well-aligned carbon nanotubes (CNTs). The polarizer was constructed on a mechanical frame over which we manually wound acid-doped CNT fibers with ultrahigh electrical conductivity. We demonstrated that the polarizer has an extinction ratio of ∼−30 dB with a low insertion loss (<0.5 dB) throughout a frequency range of 0.2–1.1 THz. In addition, we used a THz ellipsometer to measure the Müller matrix of the CNT-fiber polarizer and found comparable attenuation to a commercial metallic wire-grid polarizer. Furthermore, based on the classical theory of light transmission through an array of metallic wires, we demonstrated the most striking difference between the CNT-fiber and metallic wire-grid polarizers: the latter fails to work in the zero-spacing limit, where it acts as a simple mirror, while the former continues to work as an excellent polarizer even in that limit due to the one-dimensional conductivity of individual CNTs.

  12. TeraSCREEN: multi-frequency multi-mode Terahertz screening for border checks (United States)

    Alexander, Naomi E.; Alderman, Byron; Allona, Fernando; Frijlink, Peter; Gonzalo, Ramón; Hägelen, Manfred; Ibáñez, Asier; Krozer, Viktor; Langford, Marian L.; Limiti, Ernesto; Platt, Duncan; Schikora, Marek; Wang, Hui; Weber, Marc Andree


    The challenge for any security screening system is to identify potentially harmful objects such as weapons and explosives concealed under clothing. Classical border and security checkpoints are no longer capable of fulfilling the demands of today's ever growing security requirements, especially with respect to the high throughput generally required which entails a high detection rate of threat material and a low false alarm rate. TeraSCREEN proposes to develop an innovative concept of multi-frequency multi-mode Terahertz and millimeter-wave detection with new automatic detection and classification functionalities. The system developed will demonstrate, at a live control point, the safe automatic detection and classification of objects concealed under clothing, whilst respecting privacy and increasing current throughput rates. This innovative screening system will combine multi-frequency, multi-mode images taken by passive and active subsystems which will scan the subjects and obtain complementary spatial and spectral information, thus allowing for automatic threat recognition. The TeraSCREEN project, which will run from 2013 to 2016, has received funding from the European Union's Seventh Framework Programme under the Security Call. This paper will describe the project objectives and approach.

  13. Millimeter-wave Imaging Systems with Aperture Synthesis Techniques

    DEFF Research Database (Denmark)

    Löffler, Torsten; Krozer, Viktor; Zhurbenko, Vitaliy


    The paper describes development of a millimetre-wave imaging system using multi-element aperture filling techniques [1]. Such imaging systems are increasingly demonstrated for security applications and in particular standoff imaging of persons and bonding flaw and defect detection [2]. The major...

  14. Plasmon-enhanced terahertz emission in self-assembled quantum dots by femtosecond pulses

    Energy Technology Data Exchange (ETDEWEB)

    Carreño, F., E-mail:; Antón, M. A., E-mail:; Melle, Sonia, E-mail:; Calderón, Oscar G., E-mail:; Cabrera-Granado, E., E-mail: [Facultad de Óptica y Optometría, Universidad Complutense de Madrid, C/ Arcos de Jalón 118, 28037 Madrid (Spain); Cox, Joel, E-mail:; Singh, Mahi R., E-mail: [Department of Physics and Astronomy, The University of Western Ontario, London N6A 3K7 (Canada); Egatz-Gómez, A., E-mail: [Department of Chemical and Biomolecular Engineering, University of Notre Dame, South Bend, Indiana 46556 (United States)


    A scheme for terahertz (THz) generation from intraband transition in a self-assembled quantum dot (QD) molecule coupled to a metallic nanoparticle (MNP) is analyzed. The QD structure is described as a three-level atom-like system using the density matrix formalism. The MNP with spherical geometry is considered in the quasistatic approximation. A femtosecond laser pulse creates a coherent superposition of two subbands in the quantum dots and produces localized surface plasmons in the nanoparticle which act back upon the QD molecule via dipole-dipole interaction. As a result, coherent THz radiation with a frequency corresponding to the interlevel spacing can be obtained, which is strongly modified by the presence of the MNP. The peak value of the terahertz signal is analyzed as a function of nanoparticle's size, the MNP to QD distance, and the area of the applied laser field. In addition, we theoretically demonstrate that the terahertz pulse generation can be effectively controlled by making use of a train of femtosecond laser pulses. We show that by a proper choice of the parameters characterizing the pulse train a huge enhancement of the terahertz signal is obtained.

  15. Image recognition and neuronal networks: intelligent systems for the improvement of imaging information. (United States)

    Karkanis, S; Magoulas, G D; Theofanous, N


    Intelligent computerised systems can provide useful assistance to the physician in the rapid identification of tissue abnormalities and accurate diagnosis in real-time. This paper reviews basic issues in medical imaging and neural network-based systems for medical image interpretation. In the framework of intelligent systems, a simple scheme that has been implemented is presented as an example of the use of intelligent systems to discriminate between normal and cancerous regions in colonoscopic images. Preliminary results indicate that this scheme is capable of high accuracy detection of abnormalities within the image. It can also be successfully applied to different types of images, to detect abnormalities that belong to different cancer types.

  16. Low Quality Image Retrieval System For Generic Databases

    Directory of Open Access Journals (Sweden)

    W.A.D.N. Wijesekera


    Full Text Available Abstract Content Based Image Retrieval CBIR systems have become the trend in image retrieval technologies as the index or notation based image retrieval algorithms give less efficient results in high usage of images. These CBIR systems are mostly developed considering the availability of high or normal quality images. High availability of low quality images in databases due to usage of different quality equipment to capture images and different environmental conditions the photos are being captured has opened up a new path in image retrieval research area. The algorithms which are developed for low quality image based image retrieval are only a few and have been performed only for specific domains. Low quality image based image retrieval algorithm on a generic database with a considerable accuracy level for different industries is an area which remains unsolved. Through this study an algorithm has been developed to achieve above mentioned gaps. By using images with inappropriate brightness and compressed images as low quality images the proposed algorithm is tested on a generic database which includes many categories of data instead of using a specific domain. The new algorithm developed gives better precision and recall values when they are clustered into the most appropriate number of clusters which changes according to the level of quality of the image. As the quality of the image decreases the accuracy of the algorithm also tends to be reduced a space for further improvement.

  17. IMIS: An intelligence microscope imaging system (United States)

    Caputo, Michael; Hunter, Norwood; Taylor, Gerald


    Until recently microscope users in space relied on traditional microscopy techniques that required manual operation of the microscope and recording of observations in the form of written notes, drawings, or photographs. This method was time consuming and required the return of film and drawings from space for analysis. No real-time data analysis was possible. Advances in digital and video technologies along with recent developments in article intelligence will allow future space microscopists to have a choice of three additional modes of microscopy: remote coaching, remote control, and automation. Remote coaching requires manual operations of the microscope with instructions given by two-way audio/video transmission during critical phases of the experiment. When using the remote mode of microscopy, the Principal Investigator controls the microscope from the ground. The automated mode employs artificial intelligence to control microscope functions and is the only mode that can be operated in the other three modes as well. The purpose of this presentation is to discuss the advantages and disadvantages of the four modes of of microscopy and how the IMIS, a proposed intelligent microscope imaging system, can be used as a model for developing and testing concepts, operating procedures, and equipment design of specifications required to provide a comprehensive microscopy/imaging capability onboard Space Station Freedom.

  18. PAMS photo image retrieval prototype system requirements specification

    Energy Technology Data Exchange (ETDEWEB)

    Conner, M.L.


    This project is part of the Photo Audiovisual Management System (PAMS). The project was initially identified in 1989 and has since been has been worked on under various names such as Image Retrieval and Viewing System, Photo Image Retrieval Subsystem and Image Processing and Compression System. This document builds upon the information collected and the analysis performed in the earlier phases of this project. The PAMS Photo Imaging subsystem will provide the means of capturing low resolution digital images from Photography`s negative files and associating the digital images with a record in the PAMS photo database. The digital images and key photo identification information will be accessible to HAN users to assist in locating and identifying specific photographs. After identifying desired photographs, users may request photo prints or high resolution digital images directly from Photography. The digital images captured by this project are for identification purposes only and are not intended to be of sufficient quality for subsequent use.

  19. Real-time continuous-wave terahertz line scanner based on a compact 1 × 240 InGaAs Schottky barrier diode array detector. (United States)

    Han, Sang-Pil; Ko, Hyunsung; Kim, Namje; Lee, Won-Hui; Moon, Kiwon; Lee, Il-Min; Lee, Eui Su; Lee, Dong Hun; Lee, Wangjoo; Han, Seong-Tae; Choi, Sung-Wook; Park, Kyung Hyun


    We demonstrate real-time continuous-wave terahertz (THz) line-scanned imaging based on a 1 × 240 InGaAs Schottky barrier diode (SBD) array detector with a scan velocity of 25 cm/s, a scan line length of 12 cm, and a pixel size of 0.5 × 0.5 mm². Foreign substances, such as a paper clip with a spatial resolution of approximately 1 mm that is hidden under a cracker, are clearly detected by this THz line-scanning system. The system consists of the SBD array detector, a 200-GHz gyrotron source, a conveyor system, and several optical components such as a high-density polyethylene cylindrical lens, metal cylindrical mirror, and THz wire-grid polarizer. Using the THz polarizer, the signal-to-noise ratio of the SBD array detector improves because the quality of the source beam is enhanced.

  20. On the Design of High Resolution Imaging Systems (United States)

    Eckardt, A.; Reulke, R.


    The design of high-resolution systems is always a consideration of many parameters. Technological parameter of the imaging system, e.g. diameter of the imaging system, mass and power, as well as storage and data transfer, have an direct impact on spacecraft size and design. The paper describes the essential design parameters for the description of high-resolution systems.

  1. Automatic system for detecting pornographic images (United States)

    Ho, Kevin I. C.; Chen, Tung-Shou; Ho, Jun-Der


    Due to the dramatic growth of network and multimedia technology, people can more easily get variant information by using Internet. Unfortunately, it also makes the diffusion of illegal and harmful content much easier. So, it becomes an important topic for the Internet society to protect and safeguard Internet users from these content that may be encountered while surfing on the Net, especially children. Among these content, porno graphs cause more serious harm. Therefore, in this study, we propose an automatic system to detect still colour porno graphs. Starting from this result, we plan to develop an automatic system to search porno graphs or to filter porno graphs. Almost all the porno graphs possess one common characteristic that is the ratio of the size of skin region and non-skin region is high. Based on this characteristic, our system first converts the colour space from RGB colour space to HSV colour space so as to segment all the possible skin-colour regions from scene background. We also apply the texture analysis on the selected skin-colour regions to separate the skin regions from non-skin regions. Then, we try to group the adjacent pixels located in skin regions. If the ratio is over a given threshold, we can tell if the given image is a possible porno graph. Based on our experiment, less than 10% of non-porno graphs are classified as pornography, and over 80% of the most harmful porno graphs are classified correctly.

  2. 3D Printed Terahertz Focusing Grating Couplers (United States)

    Jahn, David; Weidenbach, Marcel; Lehr, Jannik; Becker, Leonard; Beltrán-Mejía, Felipe; Busch, Stefan F.; Balzer, Jan C.; Koch, Martin


    We have designed, constructed and characterized a grating that focuses electromagnetic radiation at specific frequencies out of a dielectric waveguide. A simple theoretical model predicts the focusing behaviour of these chirped gratings, along with numerical results that support our assumptions and improved the grating geometry. The leaky waveguide was 3D printed and characterized at 120 GHz demonstrating its potential for manipulating terahertz waves.

  3. Temperature dependent terahertz properties of Ammonium Nitrate (United States)

    Rahman, Abdur; Azad, Abul; Moore, David

    Terahertz spectroscopy has been demonstrated as an ideal nondestructive method for identifying hazardous materials such as explosives. Many common explosives exhibit distinct spectral signatures at terahertz range (0.1-6.0 THz) due to the excitations of their low frequency vibrational modes. Ammonium nitrate (AN), an easily accessible oxidizer often used in improvised explosive, exhibits strong temperature dependence. While the room temperature terahertz absorption spectrum of AN is featureless, it reveals distinct spectral features below 240 K due to the polymorphic phase transition. We employed terahertz time domain spectroscopy to measure the effective dielectric properties of AN embedded in polytetrafluoroethylene (PTFE) binder. The dielectric properties of pure AN were extracted using three different effective medium theories (EMT), simple effective medium approach, Maxwell-Garnett (MG) model, and Bruggeman (BR) model. In order to understand the effect of temperature on the dielectric properties, we varied the sample temperature from 5K to 300K. This study indicates presence of additional vibrational modes at low temperature. These results may greatly enhance the detectability of AN and facilitate more accurate theoretical modeling.

  4. Terahertz Plasmonic Structure With Enhanced Sensing Capabilities

    DEFF Research Database (Denmark)

    Yahiaoui, Riad; Strikwerda, Andrew C.; Jepsen, Peter Uhd


    We have designed, fabricated, and experimentally verified a highly sensitive plasmonic sensing device in the terahertz frequency range. For a proof of concept of the sensing phenomenon, we have chosen the so-called fishnet structure based on circular hole array insensitive to the polarization of ...

  5. Ultrabroadband terahertz spectroscopy of a liquid crystal

    DEFF Research Database (Denmark)

    Vieweg, N.; Fischer, B. M.; Reuter, M.


    Liquid crystals (LCs) are becoming increasingly important for applications in the terahertz frequency range. A detailed understanding of the spectroscopic parameters of these materials over a broad frequency range is crucial in order to design customized LC mixtures for improved performance. We p...

  6. Terahertz transport dynamics of graphene charge carriers

    DEFF Research Database (Denmark)

    Buron, Jonas Christian Due

    The electronic transport dynamics of graphene charge carriers at femtosecond (10-15 s) to picosecond (10-12 s) time scales are investigated using terahertz (1012 Hz) time-domain spectroscopy (THz-TDS). The technique uses sub-picosecond pulses of electromagnetic radiation to gauge the electrodynamic...

  7. Design Guidelines for Terahertz Mixers and Detectors

    NARCIS (Netherlands)

    Focardi, P.; McGrath, W.R.; Neto, A.


    Twin-slot antennas and coplanar waveguides are a popular choice for coupling signals to state-of-the-art mixers and detectors at terahertz frequencies. Although these sensors show promising performance in terms of noise temperature, they usually also show a considerable downward shift in the center

  8. Hot electron effect in terahertz hybrid devices

    NARCIS (Netherlands)

    Leone, B; Gao, [No Value; Klapwijk, TM; Jackson, BD; Laauwen, WM; de Lange, G

    We analyse both the direct current and submillimeter pumped cut-rent-voltage characteristics of a hybrid superconductor-insulator-superconductor terahertz, mixer consisting of a Nb tunnel junction integrated with NbTiN tuning striplines. We And that the presence of the Nb/NbTiN interface gives rise

  9. Semiconductor saturable absorbers for ultrafast terahertz signals

    DEFF Research Database (Denmark)

    Hoffmann, Matthias C.; Turchinovich, Dmitry


    We demonstrate saturable absorber behavior of n-type semiconductors GaAs, GaP, and Ge in the terahertz THz frequency range at room temperature using nonlinear THz spectroscopy. The saturation mechanism is based on a decrease in electron conductivity of semiconductors at high electron momentum...

  10. Terahertz absorption spectrum of triacetone triperoxide (TATP) (United States)

    Wilkinson, John; Konek, Christopher T.; Moran, Jesse S.; Witko, Ewelina M.; Korter, Timothy M.


    We report here, for the first time, the terahertz absorption spectrum of triacetone triperoxide (TATP). The experimental spectra are coupled with solid-state density functional theory, and preliminary assignments are provided to gain physical insight into the experimental spectrum. The calculated absorption coefficients are in excellent agreement with experiment.

  11. Recent progress in multidimensional optical sensing and imaging systems (MOSIS) (United States)

    Shen, Xin; Javidi, Bahram


    We present recent progress of the previously reported Multidimensional Optical Sensing and Imaging Systems (MOSIS) 2.0 for target recognition, material inspection and integrated visualization. The degrees of freedom of MOSIS 2.0 include three-dimensional (3D) imaging, polarimetric imaging and multispectral imaging. Each of these features provides unique information about a scene. 3D computationally reconstructed images mitigate the occlusion in front of the object, which can be used for 3D object recognition. The degree of polarization (DoP) of the light reflected from object surface is measured by 3D polarimetric imaging. Multispectral imaging is able to segment targets with specific spectral properties.

  12. Terahertz spoof surface-plasmon-polariton subwavelength waveguide

    KAUST Repository

    Zhang, Ying


    Surface plasmon polaritons (SPPs) with the features of subwavelength confinement and strong enhancements have sparked enormous interest. However, in the terahertz regime, due to the perfect conductivities of most metals, it is hard to realize the strong confinement of SPPs, even though the propagation loss could be sufficiently low. One main approach to circumvent this problem is to exploit spoof SPPs, which are expected to exhibit useful subwavelength confinement and relative low propagation loss at terahertz frequencies. Here we report the design, fabrication, and characterization of terahertz spoof SPP waveguides based on corrugated metal surfaces. The various waveguide components, including a straight waveguide, an S-bend waveguide, a Y-splitter, and a directional coupler, were experimentally demonstrated using scanning near-field terahertz microscopy. The proposed waveguide indeed enables propagation, bending, splitting, and coupling of terahertz SPPs and thus paves a new way for the development of flexible and compact plasmonic circuits operating at terahertz frequencies. (C) 2017 Chinese Laser Press

  13. Photoacoustic image-guided navigation system for surgery (Conference Presentation) (United States)

    Park, Sara; Jang, Jongseong; Kim, Jeesu; Kim, Young Soo; Kim, Chulhong


    Identifying and delineating invisible anatomical and pathological details during surgery guides surgical procedures in real time. Various intraoperative imaging modalities have been increasingly employed to minimize such surgical risks as anatomical changes, damage to normal tissues, and human error. However, current methods provide only structural information, which cannot identify critical structures such as blood vessels. The logical next step is an intraoperative imaging modality that can provide functional information. Here, we have successfully developed a photoacoustic (PA) image-guided navigation system for surgery by integrating a position tracking system and a real-time clinical photoacoustic/ultrasound (PA/US) imaging system. PA/US images were acquired in real time and overlaid on pre-acquired cross-sectional magnetic resonance (MR) images. In the overlaid images, PA images represent the optical absorption characteristics of the surgical field, while US and MR images represent the morphological structure of surrounding tissues. To test the feasibility of the system, we prepared a tissue mimicking phantom which contained two samples, methylene blue as a contrast agent and water as a control. We acquired real-time overlaid PA/US/MR images of the phantom, which were well-matched with the optical and morphological properties of the samples. The developed system is the first approach to a novel intraoperative imaging technology based on PA imaging, and we believe that the system can be utilized in various surgical environments in the near future, improving the efficacy of surgical guidance.

  14. Reconfigurable terahertz grating with enhanced transmission of TE polarized light

    Directory of Open Access Journals (Sweden)

    J. W. He


    Full Text Available We demonstrate an optically reconfigurable grating with enhanced transmission of TE-polarized waves in the terahertz (THz waveband. This kind of grating is realized by projecting a grating image onto a thin Si wafer with a digital micromirror device (DMD. The enhanced transmission is caused by a resonance of the electromagnetic fields between the photoexcited strips. The position of the transmission peak shifts with the variation of the period and duty cycle of the photoinduced grating, which can be readily controlled by the DMD. Furthermore, a flattened Gaussian model was applied to describe the distribution of the photoexcited free carriers in the Si wafer, and the simulated transmittance spectra are shown to be in good agreement with the experimental results. In future, the photoexcited carriers could also be used to produce THz diffractive elements with reconfigurable functionality.

  15. Reconfigurable terahertz grating with enhanced transmission of TE polarized light (United States)

    He, J. W.; Wang, X. K.; Xie, Z. W.; Xue, Y. Z.; Wang, S.; Zhang, Y.


    We demonstrate an optically reconfigurable grating with enhanced transmission of TE-polarized waves in the terahertz (THz) waveband. This kind of grating is realized by projecting a grating image onto a thin Si wafer with a digital micromirror device (DMD). The enhanced transmission is caused by a resonance of the electromagnetic fields between the photoexcited strips. The position of the transmission peak shifts with the variation of the period and duty cycle of the photoinduced grating, which can be readily controlled by the DMD. Furthermore, a flattened Gaussian model was applied to describe the distribution of the photoexcited free carriers in the Si wafer, and the simulated transmittance spectra are shown to be in good agreement with the experimental results. In future, the photoexcited carriers could also be used to produce THz diffractive elements with reconfigurable functionality.

  16. Numerical simulation of broadband vortex terahertz beams propagation (United States)

    Semenova, V. A.; Kulya, M. S.; Bespalov, V. G.


    Orbital angular momentum (OAM) represents new informational degree of freedom for data encoding and multiplexing in fiber and free-space communications. OAM-carrying beams (also called vortex beams) were successfully used to increase the capacity of optical, millimetre-wave and radio frequency communication systems. However, the investigation of the OAM potential for the new generation high-speed terahertz communications is also of interest due to the unlimited demand of higher capacity in telecommunications. Here we present a simulation-based study of the propagating in non-dispersive medium broadband terahertz vortex beams generated by a spiral phase plate (SPP). The algorithm based on scalar diffraction theory was used to obtain the spatial amplitude and phase distributions of the vortex beam in the frequency range from 0.1 to 3 THz at the distances 20-80 mm from the SPP. The simulation results show that the amplitude and phase distributions without unwanted modulation are presented in the wavelengths ranges with centres on the wavelengths which are multiple to the SPP optical thickness. This fact may allow to create the high-capacity near-field communication link which combines OAM and wavelength-division multiplexing.

  17. Discrimination of genetically modified sugar beets based on terahertz spectroscopy. (United States)

    Chen, Tao; Li, Zhi; Yin, Xianhua; Hu, Fangrong; Hu, Cong


    The objective of this paper was to apply terahertz (THz) spectroscopy combined with chemometrics techniques for discrimination of genetically modified (GM) and non-GM sugar beets. In this paper, the THz spectra of 84 sugar beet samples (36 GM sugar beets and 48 non-GM ones) were obtained by using terahertz time-domain spectroscopy (THz-TDS) system in the frequency range from 0.2 to 1.2 THz. Three chemometrics methods, principal component analysis (PCA), discriminant analysis (DA) and discriminant partial least squares (DPLS), were employed to classify sugar beet samples into two groups: genetically modified organisms (GMOs) and non-GMOs. The DPLS method yielded the best classification result, and the percentages of successful classification for GM and non-GM sugar beets were both 100%. Results of the present study demonstrate the usefulness of THz spectroscopy together with chemometrics methods as a powerful tool to distinguish GM and non-GM sugar beets. Copyright © 2015 Elsevier B.V. All rights reserved.

  18. Radionuclide Imaging Technologies for Biological Systems

    Energy Technology Data Exchange (ETDEWEB)

    Howell, Calvin R. [Duke Univ., Durham, NC (United States); Reid, Chantal D. [Duke Univ., Durham, NC (United States); Weisenberger, Andrew G. [Thomas Jefferson National Accelerator Facility (TJNAF), Newport News, VA (United States)


    The main objective of this project is to develop technologies and experimental techniques for studying the dynamics of physiological responses of plants to changes in their interface with the local environment and to educate a new generation of scientists in an interdisciplinary environment of biology, physics and engineering. Also an important goal is to perform measurements to demonstrate the new data that can be produced and made available to the plant-biology community using the imaging technologies and experimental techniques developed in this project. The study of the plant-environment interface includes a wide range of topics in plant physiology, e.g., the root-soil interface, resource availability, impact of herbivores, influence of microbes on root surface, and responses to toxins in the air and soil. The initial scientific motivation for our work is to improve understanding of the mechanisms for physiological responses to abrupt changes in the local environment, in particular, the responses that result in short-term adjustments in resource (e.g., sugars, nutrients and water) allocations. Data of time-dependent responses of plants to environmental changes are essential in developing mechanistic models for substance intake and resource allocation. Our approach is to use radioisotope tracing techniques to study whole-plant and plant organ (e.g., leaves, stems, roots) dynamical responses to abrupt changes in environmental conditions such as concentration of CO2 in the atmosphere, nutrient availability and lighting. To this aim we are collaborating with the Radiation Detector and Imaging Group at the Thomas Jefferson National Laboratory Facility (JLab) to develop gamma-ray and beta particle imaging systems optimized for plant studies. The radioisotope tracing measurements are conducted at the Phytotron facility at Duke University. The Phytotron is a controlled environment plant research facility with a variety of plant growth chambers. One chamber

  19. Electromagnetic fields in biological systems

    National Research Council Canada - National Science Library

    Lin, James C


    "Focusing on exposure, induced fields, and absorbed energy, this volume covers the interaction of electromagnetic fields and waves with biological systems, spanning static fields to terahertz waves...

  20. Investigation of physical imaging properties in various digital radiography systems

    Energy Technology Data Exchange (ETDEWEB)

    Jeong, Hoi Woun [Dept. of Radiological Science, Baekseok Culture University, Cheonan (Korea, Republic of); Min, Jung Hwan [Dept. of Radiological technology, Shingu University, Seongnam (Korea, Republic of); Yoon, Yong Su [Dept. of Health Sciences, Graduate School of Medical Sciences, Kyushu University, Kyushu (Japan); Kim, Jung Min [Dept. of Health and Environmental Science, College of Health Science, Korea University, Seoul (Korea, Republic of)


    We aimed to evaluate the physical imaging properties in various digital radiography systems with charged coupled device (CCD), computed radiography (CR), and indirect flat panel detector (FPD). The imaging properties measured in this study were modulation transfer function (MTF) wiener spectrum (WS), and detective quantum efficiency (DQE) to compare the performance of each digital radiography system. The system response of CCD were in a linear relationship with exposure and that of CR and FPD were proportional to the logarithm of exposure. The MTF of both CR and FPD indicated a similar tendency but in case of CCD, it showed lower MTF than that of CR and FPD. FPD showed the lowest WS and also indicated the highest DQE among three systems. According to the results, digital radiography system with different type of image receptor had its own image characteristics. Therefore, it is important to know the physical imaging characteristics of the digital radiography system accurately to obtain proper image quality.

  1. Optimization of a Biometric System Based on Acoustic Images

    Directory of Open Access Journals (Sweden)

    Alberto Izquierdo Fuente


    Full Text Available On the basis of an acoustic biometric system that captures 16 acoustic images of a person for 4 frequencies and 4 positions, a study was carried out to improve the performance of the system. On a first stage, an analysis to determine which images provide more information to the system was carried out showing that a set of 12 images allows the system to obtain results that are equivalent to using all of the 16 images. Finally, optimization techniques were used to obtain the set of weights associated with each acoustic image that maximizes the performance of the biometric system. These results improve significantly the performance of the preliminary system, while reducing the time of acquisition and computational burden, since the number of acoustic images was reduced.

  2. Optimization of a Biometric System Based on Acoustic Images (United States)

    Izquierdo Fuente, Alberto; Del Val Puente, Lara; Villacorta Calvo, Juan J.; Raboso Mateos, Mariano


    On the basis of an acoustic biometric system that captures 16 acoustic images of a person for 4 frequencies and 4 positions, a study was carried out to improve the performance of the system. On a first stage, an analysis to determine which images provide more information to the system was carried out showing that a set of 12 images allows the system to obtain results that are equivalent to using all of the 16 images. Finally, optimization techniques were used to obtain the set of weights associated with each acoustic image that maximizes the performance of the biometric system. These results improve significantly the performance of the preliminary system, while reducing the time of acquisition and computational burden, since the number of acoustic images was reduced. PMID:24616643

  3. Advanced Signal Processing Techniques Applied to Terahertz Inspections on Aerospace Foams (United States)

    Trinh, Long Buu


    The space shuttle's external fuel tank is thermally insulated by the closed cell foams. However, natural voids composed of air and trapped gas are found as by-products when the foams are cured. Detection of foam voids and foam de-bonding is a formidable task owing to the small index of refraction contrast between foam and air (1.04:1). In the presence of a denser binding matrix agent that bonds two different foam materials, time-differentiation of filtered terahertz signals can be employed to magnify information prior to the main substrate reflections. In the absence of a matrix binder, de-convolution of the filtered time differential terahertz signals is performed to reduce the masking effects of antenna ringing. The goal is simply to increase probability of void detection through image enhancement and to determine the depth of the void.

  4. Terahertz radiation source using a high-power industrial electron linear accelerator (United States)

    Kalkal, Yashvir; Kumar, Vinit


    High-power (˜ 100 kW) industrial electron linear accelerators (linacs) are used for irradiations, e.g., for pasteurization of food products, disinfection of medical waste, etc. We propose that high-power electron beam from such an industrial linac can first pass through an undulator to generate useful terahertz (THz) radiation, and the spent electron beam coming out of the undulator can still be used for the intended industrial applications. This will enhance the utilization of a high-power industrial linac. We have performed calculation of spontaneous emission in the undulator to show that for typical parameters, continuous terahertz radiation having power of the order of μW can be produced, which may be useful for many scientific applications such as multispectral imaging of biological samples, chemical samples etc.

  5. Widely Tunable Terahertz Phase Modulation with Gate-Controlled Graphene Metasurfaces

    Directory of Open Access Journals (Sweden)

    Ziqi Miao


    Full Text Available As the basis of a diverse set of photonic applications, such as hologram imaging, polarization, and wave front manipulation, the local phase control of electromagnetic waves is fundamental in photonic research. However, currently available bulky, passive, range-limited phase modulators pose an obstacle in photonic applications. Here, we propose a new mechanism to achieve a wide phase modulation range, with graphene used as a tunable loss to drive an underdamped to overdamped resonator transition. Based on this mechanism, we present widely tunable phase modulation in the terahertz regime, realized in gate-tuned ultrathin reflective graphene metasurfaces. A one-port resonator model, supported by full-wave simulations, explains the underlying physics of the discovered extreme phase modulation and indicates general strategies for designing tunable photonic devices. As an example, we demonstrate a gate-tunable terahertz (THz polarization modulator with a graphene metasurface. Our findings establish the possibility for photonic applications based on active phase manipulation.

  6. Ultra-broadband and polarization-insensitive wide-angle terahertz metamaterial absorber (United States)

    Li, Xinwang; Liu, Hongjun; Sun, Qibing; Huang, Nan


    In this paper, an ultra-broadband and polarization insensitive terahertz (THz) metamaterial absorber is presented and investigated. With the optimization of the structural parameters, resonant peaks are merged into a broadband absorption spectrum. The simulation results demonstrate that a wide bandwidth of 3.1 THz is obtained in the range from 2.6 to 5.7 THz, where the absorption is higher than 90% for the normal incident THz waves. The full width at half maximum (FWHM) of absorption spectrum is 95% with respect to central frequency (∼4 THz), which is five times greater than the FWHM of a single layer structure. Furthermore, this structure can keep the absorption above 88% over a large frequency range (>2.5 THz) when the incident angle is smaller than 50°. This metamaterial absorber can find potential applications in terahertz imaging and stealth technology.

  7. Enhanced circular dichroism based on the dual-chiral metamaterial in terahertz regime (United States)

    Jian, Shao; Jie, Li; Ying-Hua, Wang; Jia-Qi, Li; Zheng-Gao, Dong; Lin, Zhou


    The obvious circular dichroism (CD) and optical activity can be obtained based on the chiral metamaterial due to the plasmon-enhanced effect, which is very attractive for future compact devices with enhanced capabilities of light manipulation. In this paper, we propose a dual-chiral metamaterial composed of bilayer asymmetric split ring resonators (ASRR) that are in mirror-symmetry shape. It is demonstrated that the CD can get enhancement in the terahertz regime. Moreover, the CD can be further improved by modulating the asymmetry of ASRR. The enhanced CD effect in the terahertz regime has great potential applications in sensing, biomedical imaging, and molecular recognition. Project supported by the National Natural Science Foundation of China (Grant Nos. 11174051, 11374049, and 11204139), the Natural Science Foundation of Jiangsu Province of China (Grant No. BK20131283), and the Fundamental Research Funds for the Central Universities, China.

  8. Terahertz surface plasmon polariton waveguiding with periodic metallic cylinders

    KAUST Repository

    Zhang, Ying


    We demonstrated a structure with periodic cylinders arranged bilaterally and a thin dielectric layer covered inside that supports bound modes of surface plasmon polaritons at terahertz frequencies. This structure can confine the surface plasmon polaritons in the lateral direction, and at the same time reduce the field expansion into space. We examined and explored the characteristics of several different structures using scanning near-field terahertz microscopy. The proposed designs pave a novel way to terahertz waveguiding and may have important applications in the development of flexible, wideband and compact photonic circuits operating at terahertz frequencies.

  9. Rotatable illusion media for manipulating terahertz electromagnetic waves

    National Research Council Canada - National Science Library

    Zang, XiaoFei; Li, Zhou; Shi, Cheng; Chen, Lin; Cai, Bin; Zhu, YiMing; Li, Li; Wang, XiaoBin


    Based on composite optical transformation, we propose a rotatable illusion media with positive permittivity and permeability to manipulate terahertz waves, and a new way to realize singular parameter...

  10. Near optimal graphene terahertz non-reciprocal isolator

    National Research Council Canada - National Science Library

    Tamagnone, Michele; Moldovan, Clara; Poumirol, Jean-Marie; Kuzmenko, Alexey B; Ionescu, Adrian M; Mosig, Juan R; Perruisseau-Carrier, Julien


    .... Here we report the design, fabrication and measurement of a terahertz non-reciprocal isolator for circularly polarized waves based on magnetostatically biased monolayer graphene, operating in reflection...

  11. A simple polarized-based diffused reflectance colour imaging system

    African Journals Online (AJOL)

    A simple polarized-based diffuse reflectance imaging system has been developed. The system is designed for both in vivo and in vitro imaging of agricultural specimen in the visible region. The system uses a commercial web camera and a halogen lamp that makes it relatively simple and less expensive for diagnostic ...

  12. Uses of nanoparticles for central nervous system imaging and therapy. (United States)

    Provenzale, J M; Silva, G A


    Applications of nanotechnology to medicine are leading to novel means of imaging living systems and of delivering therapy. Much nanotechnology research is focused on methods for imaging central nervous system functions and disease states. In this review, the principles of nanoparticle design and function are discussed with specific emphasis on applications to neuroradiology. In addition to innovative forms of imaging, this review describes therapeutic uses of nanoparticles, such as drug delivery systems, neuroprotection devices, and methods for tissue regeneration.

  13. Scaling behavior of ultrafast two-color terahertz generation in plasma gas targets: energy and pressure dependence. (United States)

    Rodriguez, George; Dakovski, Georgi L


    Ultrafast terahertz emission from two-color generated laser plasma gas targets is studied using air and the noble gases (neon, argon, krypton, and xenon) as the generation media. Terahertz output pulse energy and power spectra are measured as function of gas species, gas pressure, and input pulse energy up to 6 mJ per pulse using a 40-fs 1-kHz Ti:sapphire laser system as the drive source. Terahertz pulse energies approaching 1 microJ per pulse with spectral content out to 40 THz and pulse duration of 35 fs is reported. A simple one dimensional transient photocurrent ionization model is used to calculate the spectra showing good agreement with experiments.

  14. Efficient Terahertz Plasmonic Absorbers with V-Grooves Using Highly Doped Silicon Substrate and Simple Wet-Etching Techniques (United States)

    Zhai, Mengfei; Yuan, Wei; Han, Zhanghua


    We experimentally demonstrate that at terahertz frequencies perfect plasmonic absorbers made from a 3D V-groove array in a highly doped silicon wafer can be easily realized using simple wet-etching process. The surface plasmon modes can be excited by the V-groove array and get decayed when they propagate along the silicon surface and enter the grooves, inducing a broadband near-zero dip in the reflection spectra. The reflection spectrum of the fabricated absorber is characterized using a terahertz time-domain spectroscopy system, and the experimental results are in good agreement with numerical simulations. The high performance including high absorptivity and large bandwidth together with the easy fabrication processes presented in this paper make this plasmonic absorber promising for a wide range of practical applications in terahertz regime.

  15. The operation technology of realtime image processing system (Datacube)

    Energy Technology Data Exchange (ETDEWEB)

    Cho, Jai Wan; Lee, Yong Bum; Lee, Nam Ho; Choi, Young Soo; Park, Soon Yong; Park, Jin Seok


    In this project, a Sparc VME-based MaxSparc system, running the solaris operating environment, is selected as the dedicated image processing hardware for robot vision applications. In this report, the operation of Datacube maxSparc system, which is high performance realtime image processing hardware, is systematized. And image flow example programs for running MaxSparc system are studied and analyzed. The state-of-the-arts of Datacube system utilizations are studied and analyzed. For the next phase, advanced realtime image processing platform for robot vision application is going to be developed. (author). 19 refs., 71 figs., 11 tabs.

  16. Integrating medical imaging analyses through a high-throughput bundled resource imaging system (United States)

    Covington, Kelsie; Welch, E. Brian; Jeong, Ha-Kyu; Landman, Bennett A.


    Exploitation of advanced, PACS-centric image analysis and interpretation pipelines provides well-developed storage, retrieval, and archival capabilities along with state-of-the-art data providence, visualization, and clinical collaboration technologies. However, pursuit of integrated medical imaging analysis through a PACS environment can be limiting in terms of the overhead required to validate, evaluate and integrate emerging research technologies. Herein, we address this challenge through presentation of a high-throughput bundled resource imaging system (HUBRIS) as an extension to the Philips Research Imaging Development Environment (PRIDE). HUBRIS enables PACS-connected medical imaging equipment to invoke tools provided by the Java Imaging Science Toolkit (JIST) so that a medical imaging platform (e.g., a magnetic resonance imaging scanner) can pass images and parameters to a server, which communicates with a grid computing facility to invoke the selected algorithms. Generated images are passed back to the server and subsequently to the imaging platform from which the images can be sent to a PACS. JIST makes use of an open application program interface layer so that research technologies can be implemented in any language capable of communicating through a system shell environment (e.g., Matlab, Java, C/C++, Perl, LISP, etc.). As demonstrated in this proof-of-concept approach, HUBRIS enables evaluation and analysis of emerging technologies within well-developed PACS systems with minimal adaptation of research software, which simplifies evaluation of new technologies in clinical research and provides a more convenient use of PACS technology by imaging scientists.

  17. Building an Image-Based System to automatically Score psoriasis

    DEFF Research Database (Denmark)

    G{'o}mez, D. Delgado; Carstensen, Jens Michael; Ersbøll, Bjarne Kjær


    the images. The system is tested on patients with the dermatological disease psoriasis. Temporal series of images are taken for each patient and the lesions are automatically extracted. Results indicate that to the images obtained are a good source for obtaining derived variables to track the lesion....

  18. Infrared Images of an Infant Solar System (United States)


    ESO Telescopes Detect a Strange-Looking Object Summary Using the ESO 3.5-m New Technology Telescope and the Very Large Telescope (VLT) , a team of astronomers [1] have discovered a dusty and opaque disk surrounding a young solar-type star in the outskirts of a dark cloud in the Milky Way. It was found by chance during an unrelated research programme and provides a striking portrait of what our Solar System must have looked like when it was in its early infancy. Because of its striking appearance, the astronomers have nicknamed it the "Flying Saucer" . The new object appears to be a perfect example of a very young star with a disk in which planets are forming or will soon form, and located far away from the usual perils of an active star-forming environment . Most other young stars, especially those that are born in dense regions, run a serious risk of having their natal dusty disks destroyed by the blazing radiation of their more massive and hotter siblings in these clusters. The star at the centre of the "Flying Saucer", seems destined to live a long and quiet life at the centre of a planetary system , very much like our own Sun. This contributes to making it a most interesting object for further studies with the VLT and other telescopes. The mass of the observed disk of gas and dust is at least twice that of the planet Jupiter and its radius measures about 45 billion km, or 5 times the size of the orbit of Neptune. PR Photo 12a/02 : The "Flying Saucer" object photographed with NTT/SOFI. PR Photo 12b/02 : VLT/ISAAC image of this object. PR Photo 12c/02 : Enlargement of VLT/ISAAC image . Circumstellar Disks and Planets Planets form in dust disks around young stars. This is a complex process of which not all stages are yet fully understood but it begins when small dust particles collide and stick to each other. For this reason, observations of such dust disks, in particular those that appear as extended structures (are "resolved"), are very important for our

  19. [A three-dimensional transrectal ultrasound imaging system]. (United States)

    Chen, Yimin; Qi, Jian; Ding, Mingyue; Zhang, Xuming


    A three-dimensional (3D) transrectal ultrasound (TRUS) imaging system is presented in this paper. The 3D imaging system is used for diagnosing diseases of prostate. The 3D image is reconstructed by a series of two-dimensional image data which is obtained through rectum. It can be a guide to prostate needle biopsies. The system is built by two parts: hardware and software. In the hardware, the mechanical device, stepper motor, control circuit, B Mode TRUS and personal computer (PC) workshop are presented. The software includes the firmware of micro control unit and software of the PC workshop. In order to evaluate the performance of the 3D imaging system, we did experiments with water and agar phantoms, and the results demonstrated the system's ability of 3D imaging with high-precision.

  20. Time-resolved terahertz spectroscopy of charge carrier dynamics in the chalcogenide glass As30Se30Te40 [Invited

    DEFF Research Database (Denmark)

    Wang, Tianwu; Romanova, Elena A.; Abdel-Moneim, Nabil


    Broadband (1.6-18 THz) terahertz time-domain spectroscopy (THz-TDS) and time-resolved terahertz spectroscopy (TRTS) were performed on a 54 mu m thick chalcogenide glass (As30Se30Te40) sample with a two-color laser-induced air plasma THz system in transmission and reflection modes, respectively. Two...... by the Drude-Smith conductivity model with a carrier scattering time of 12-17 fs, and we observe significant carrier localization effects. A fast refractive index change was observed 100 fs before the conductivity reached its maximum, with 2 orders of magnitude larger amplitude than expected for the optically...

  1. Squeezing terahertz light into nanovolumes: Nanoantenna enhanced terahertz spectroscopy (NETS) of semiconductor quantum dots

    KAUST Repository

    Toma, Andrea


    Terahertz spectroscopy has vast potentialities in sensing a broad range of elementary excitations (e.g., collective vibrations of molecules, phonons, excitons, etc.). However, the large wavelength associated with terahertz radiation (about 300 μm at 1 THz) severely hinders its interaction with nano-objects, such as nanoparticles, nanorods, nanotubes, and large molecules of biological relevance, practically limiting terahertz studies to macroscopic ensembles of these compounds, in the form of thick pellets of crystallized molecules or highly concentrated solutions of nanomaterials. Here we show that chains of terahertz dipole nanoantennas spaced by nanogaps of 20 nm allow retrieving the spectroscopic signature of a monolayer of cadmium selenide quantum dots, a significant portion of the signal arising from the dots located within the antenna nanocavities. A Fano-like interference between the fundamental antenna mode and the phonon resonance of the quantum dots is observed, accompanied by an absorption enhancement factor greater than one million. NETS can find immediate applications in terahertz spectroscopic studies of nanocrystals and molecules at extremely low concentrations. Furthermore, it shows a practicable route toward the characterization of individual nano-objects at these frequencies.

  2. Squeezing terahertz light into nanovolumes: nanoantenna enhanced terahertz spectroscopy (NETS) of semiconductor quantum dots. (United States)

    Toma, Andrea; Tuccio, Salvatore; Prato, Mirko; De Donato, Francesco; Perucchi, Andrea; Di Pietro, Paola; Marras, Sergio; Liberale, Carlo; Proietti Zaccaria, Remo; De Angelis, Francesco; Manna, Liberato; Lupi, Stefano; Di Fabrizio, Enzo; Razzari, Luca


    Terahertz spectroscopy has vast potentialities in sensing a broad range of elementary excitations (e.g., collective vibrations of molecules, phonons, excitons, etc.). However, the large wavelength associated with terahertz radiation (about 300 μm at 1 THz) severely hinders its interaction with nano-objects, such as nanoparticles, nanorods, nanotubes, and large molecules of biological relevance, practically limiting terahertz studies to macroscopic ensembles of these compounds, in the form of thick pellets of crystallized molecules or highly concentrated solutions of nanomaterials. Here we show that chains of terahertz dipole nanoantennas spaced by nanogaps of 20 nm allow retrieving the spectroscopic signature of a monolayer of cadmium selenide quantum dots, a significant portion of the signal arising from the dots located within the antenna nanocavities. A Fano-like interference between the fundamental antenna mode and the phonon resonance of the quantum dots is observed, accompanied by an absorption enhancement factor greater than one million. NETS can find immediate applications in terahertz spectroscopic studies of nanocrystals and molecules at extremely low concentrations. Furthermore, it shows a practicable route toward the characterization of individual nano-objects at these frequencies.

  3. Progress report on Safe VISITOR: approaching a practical instrument for terahertz security screening (United States)

    Heinz, Erik; Born, Detlef; Zieger, Gabriel; May, Torsten; Krause, Torsten; Krüger, Andre; Schulz, Marco; Anders, Solveig; Zakosarenko, Viatcheslav; Meyer, Hans-Georg; Starkloff, Michael; Rößler, Mario; Thorwirth, Guenter; Krause, Ulf


    As reported before,1, 2 Safe VISITOR (Safe VISible, Infrared and Terahertz Object recognition) is a German project to build a passive security camera which visualizes sub-mm wavelengths using cooled bolometer arrays. This camera could be used for a variety of application scenarios, such as airport screenings or to protect military camps. In all cases, a practical instrument requires ease of use, in particular a flexible installation and a straightforward usage by the security personnel. Here we present a new generation of Safe VISITOR designed to meet these requirements. The main condition for an effective operation is a high frame rate of the imager. Safe VISITOR is able to record videos up to 10 Hz, using a small array of superconducting bolometers in combination with an opto-mechanical scanner. The required cooling of the detector array is provided by a commercial pulse tube cooler with a second, self-contained cooling stage. The cooling cycle is completely automated; after 10 hours of initial cooling from room temperature the system can operate quasi-continuously. For imaging, a 50 cm diameter optics is used which is able to provide an object resolution of approximately 1.5 cm at 8 m distance. For a flexible installation, the object distance can be tuned manually between 7 and 10 m. Additionally, video streams from two commercial cameras are fused with the sub-mm stream: a CCD for visible light and a microbolometer for far infrared (14 μm). This combines the ability of identification of the person under test with the unprecedented temperature resolution at infrared and the almost perfect transmission at sub-mm. To assist a security official, all image data are displayed in various graphic renditions by a unified system software.

  4. System refinement for content based satellite image retrieval

    Directory of Open Access Journals (Sweden)

    NourElDin Laban


    Full Text Available We are witnessing a large increase in satellite generated data especially in the form of images. Hence intelligent processing of the huge amount of data received by dozens of earth observing satellites, with specific satellite image oriented approaches, presents itself as a pressing need. Content based satellite image retrieval (CBSIR approaches have mainly been driven so far by approaches dealing with traditional images. In this paper we introduce a novel approach that refines image retrieval process using the unique properties to satellite images. Our approach uses a Query by polygon (QBP paradigm for the content of interest instead of using the more conventional rectangular query by image approach. First, we extract features from the satellite images using multiple tiling sizes. Accordingly the system uses these multilevel features within a multilevel retrieval system that refines the retrieval process. Our multilevel refinement approach has been experimentally validated against the conventional one yielding enhanced precision and recall rates.

  5. The neutron imaging system fielded at the National Ignition Facility

    Directory of Open Access Journals (Sweden)

    Fittinghoff D.N.


    Full Text Available We have fielded a neutron imaging system at the National Ignition Facility to collect images of fusion neutrons produced in the implosion of inertial confinement fusion experiments and scattered neutrons from (n, n′ reactions of the source neutrons in the surrounding dense material. A description of the neutron imaging system is presented, including the pinhole array aperture, the line-of-sight collimation, the scintillator-based detection system and the alignment systems and methods. Discussion of the alignment and resolution of the system is presented. We also discuss future improvements to the system hardware.

  6. The Neutron Imaging System Fielded at the National Ignition Facility

    Energy Technology Data Exchange (ETDEWEB)

    Fittinghoff, D N; Atkinson, D P; Bower, D E; Drury, O B; Dzenitis, J M; Felker, B; Frank, M; Liddick, S N; Moran, M J; Roberson, G P; Weiss, P B; Grim, G P; Aragonez, R J; Archuleta, T N; Batha, S H; Clark, D D; Clark, D J; Danly, C R; Day, R D; Fatherley, V E; Finch, J P; Garcia, F P; Gallegos, R A; Guler, N; Hsu, A H; Jaramillo, S A; Loomis, E N; Mares, D; Martinson, D D; Merrill, F E; Morgan, G L; Munson, C; Murphy, T J; Oertel, J A; Polk, P J; Schmidt, D W; Tregillis, I L; Valdez, A C; Volegov, P L; Wang, T F; Wilde, C H; Wilke, M D; Wilson, D C; Buckles, R A; Cradick, J R; Kaufman, M I; Lutz, S S; Malone, R M; Traille, A


    We have fielded a neutron imaging system at the National Ignition Facility to collect images of fusion neutrons produced in the implosion of inertial confinement fusion experiments and scattered neutrons from (n, n') reactions of the source neutrons in the surrounding dense material. A description of the neutron imaging system will be presented, including the pinhole array aperture, the line-of-sight collimation, the scintillator-based detection system and the alignment systems and methods. Discussion of the alignment and resolution of the system will be presented. We will also discuss future improvements to the system hardware.

  7. Ultrasound Vector Flow Imaging: Part II: Parallel Systems

    DEFF Research Database (Denmark)

    Jensen, Jørgen Arendt; Nikolov, Svetoslav Ivanov; Yu, Alfred C. H.


    The paper gives a review of the current state-of-theart in ultrasound parallel acquisition systems for flow imaging using spherical and plane waves emissions. The imaging methods are explained along with the advantages of using these very fast and sensitive velocity estimators. These experimental...... ultrasound imaging for studying brain function in animals. The paper explains the underlying acquisition and estimation methods for fast 2-D and 3-D velocity imaging and gives a number of examples. Future challenges and the potentials of parallel acquisition systems for flow imaging are also discussed....

  8. Cancellation of Fabry-Perot interference effects in terahertz time-domain spectroscopy of optically thin samples (United States)

    Fastampa, Renato; Pilozzi, Laura; Missori, Mauro


    Terahertz time-domain spectroscopy is increasingly used in many fields of research. For strongly absorbing materials with refraction index close to 1, optical parameters at terahertz frequencies are most conveniently quantified using transmission measurements through thin samples. Unfortunately, extracting optical parameters from raw data implies the use and/or development of complicated numerical data processing procedures. In this work we present an efficient computational procedure for extracting the optical parameters in very thin samples (≲100 μ m) from transmission terahertz time-domain spectroscopy. In our procedure, we are able to successfully remove from raw data the Fabry-Perot interference effects, which are commonly recognized to be the leading cause of inaccuracy in the extracted parameters, introducing fictitious oscillations in their frequency dependence. The procedure is based on the Davidenko method to identify the roots of complex functions used to numerically solve the implicit equation obtained by equating the experimental and theoretical transfer functions. The advantage of the method is the possibility of obtaining the roots using the numerical solution of a system of real differential equations using standard mathematical packages. In addition, we show that complete removal of the Fabry-Perot oscillations is achieved by including in the computational procedure, besides the sample thickness, the instrumental error on the starting instant of the terahertz signal sampling. This error could be common to many terahertz time-domain systems, especially those using optical fibers. This correction is necessary in general to preserve the terahertz spectroscopic features in the extracted optical parameters for strongly absorbing materials with refraction index close to 1, such as water, biological matter, and several organic materials.

  9. PICASSO: an end-to-end image simulation tool for space and airborne imaging systems (United States)

    Cota, Stephen A.; Bell, Jabin T.; Boucher, Richard H.; Dutton, Tracy E.; Florio, Christopher J.; Franz, Geoffrey A.; Grycewicz, Thomas J.; Kalman, Linda S.; Keller, Robert A.; Lomheim, Terrence S.; Paulson, Diane B.; Wilkinson, Timothy S.


    The design of any modern imaging system is the end result of many trade studies, each seeking to optimize image quality within real world constraints such as cost, schedule and overall risk. Image chain analysis - the prediction of image quality from fundamental design parameters - is an important part of this design process. At The Aerospace Corporation we have been using a variety of image chain analysis tools for many years, the Parameterized Image Chain Analysis & Simulation SOftware (PICASSO) among them. In this paper we describe our PICASSO tool, showing how, starting with a high quality input image and hypothetical design descriptions representative of the current state of the art in commercial imaging satellites, PICASSO can generate standard metrics of image quality in support of the decision processes of designers and program managers alike.

  10. An Image Stabilization Optical System Using Deformable Freeform Mirrors

    Directory of Open Access Journals (Sweden)

    Qun Hao


    Full Text Available An image stabilization optical system using deformable freeform mirrors is proposed that enables the ray sets to couple dynamically in the object and image space. It aims to correct image blurring and degradation when there is relative movement between the imaging optical axis and the object. In this method, Fermat’s principle and matrix methods are used to describe the optical path of the entire optical system with a shift object plane and a fixed corresponding image plane in the carrier coordinate system. A constant optical path length is determined for each ray set, so the correspondence between the object and the shift free image point is used to calculate the solution to the points on the surface profile of the deformable mirrors (DMs. Off-axis three-mirror anastigmats are used to demonstrate the benefits of optical image stabilization with one- and two-deformable mirrors.

  11. Image Registration Algorithm For A PC-Based System (United States)

    Nutter, Brian S.; Mitra, Sunanda; Krile, Thomas F.


    Image registration algorithms are essential for subtractive analysis of sequential images. Discrepancies in lighting, image orientation, and scale must be minimized before effective subtraction of two images can occur. We have successfully implemented computationally intensive algorithms for registration, which include illuminance normalization and magnification correction, in a PC-based image processing system. A homomorphic filter in the spatial domain is used to reduce the illumination variations in the images. A modified sequential similarity detection technique is used to derive the minimum error factor associated with each combination of translation, magnification, and rotation variations. Each variation of the test image is masked with one of three masks, and the squares of the pixel intensity differences are summed for every test image. An adaptive threshold is used to decrease the time required for a misfit by aborting the test image under consideration when its summation exceeds the value of the previous best fit summation. After the best fit parameters are obtained, they are used to register the images so that the images can be subtracted. The difference image is subjected to further image enhancement operations. The execution time of the image registration algorithm has been reduced through use of a hybrid program written in C and Assembly languages. Applications of the registration algorithms in analysis of fundus images will be presented.

  12. Hybrid Compton camera/coded aperture imaging system (United States)

    Mihailescu, Lucian [Livermore, CA; Vetter, Kai M [Alameda, CA


    A system in one embodiment includes an array of radiation detectors; and an array of imagers positioned behind the array of detectors relative to an expected trajectory of incoming radiation. A method in another embodiment includes detecting incoming radiation with an array of radiation detectors; detecting the incoming radiation with an array of imagers positioned behind the array of detectors relative to a trajectory of the incoming radiation; and performing at least one of Compton imaging using at least the imagers and coded aperture imaging using at least the imagers. A method in yet another embodiment includes detecting incoming radiation with an array of imagers positioned behind an array of detectors relative to a trajectory of the incoming radiation; and performing Compton imaging using at least the imagers.

  13. Noise simulation system for determining imaging conditions in digital radiography (United States)

    Tanaka, R.; Ichikawa, K.; Matsubara, K.; Kawashima, H.


    Reduction of exposure dose and improvement in image quality can be expected to result from advances in the performance of imaging detectors. We propose a computerized method for determining optimized imaging conditions by use of simulated images. This study was performed to develop a prototype system for image noise and to ensure consistency between the resulting images and actual images. An RQA5 X-ray spectrum was used for determination of input-output characteristics of a flat-panel detector (FPD). The number of incident quantum to the detector per pixel (counts/pixel) was calculated according to the pixel size of the detector and the quantum number in RQA5 determined in IEC6220-1. The relationship among tube current-time product (mAs), exposure dose (C/kg) at the detector surface, the number of incident quanta (counts/pixel), and pixel values measured on the images was addressed, and a conversion function was then created. The images obtained by the FPD was converted into a map of incident quantum numbers and input into random-value generator to simulate image noise. In addition, graphic user interface was developed to observe images with changing image noise and exposure dose levels, which have trade-off relationship. Simulation images provided at different noise levels were compared with actual images obtained by the FPD system. The results indicated that image noise was simulated properly both in objective and subjective evaluation. The present system could allow us to determine necessary dose from image quality and also to estimate image quality from any exposure dose.

  14. Multi region based image retrieval system

    Indian Academy of Sciences (India)

    /fulltext/sadh/039/02/0333-0344 ... The paramount challenge is to translate or convert a visual query from a human and find similar images or videos in large digital collection. In this paper, a technique of region based image retrieval, a branch ...

  15. Highly intense monocycle terahertz vortex generation by utilizing a Tsurupica spiral phase plate. (United States)

    Miyamoto, Katsuhiko; Kang, Bong Joo; Kim, Won Tae; Sasaki, Yuta; Niinomi, Hiromasa; Suizu, Koji; Rotermund, Fabian; Omatsu, Takashige


    Optical vortex, possessing an annular intensity profile and an orbital angular momentum (characterized by an integer termed a topological charge) associated with a helical wavefront, has attracted great attention for diverse applications due to its unique properties. In particular for terahertz (THz) frequency range, several approaches for THz vortex generation, including molded phase plates consisting of metal slit antennas, achromatic polarization elements and binary-diffractive optical elements, have been recently proposed, however, they are typically designed for a specific frequency. Here, we demonstrate highly intense broadband monocycle vortex generation near 0.6 THz by utilizing a polymeric Tsurupica spiral phase plate in combination with tilted-pulse-front optical rectification in a prism-cut LiNbO3 crystal. A maximum peak power of 2.3 MW was obtained for THz vortex output with an expected topological charge of 1.15. Furthermore, we applied the highly intense THz vortex beam for studying unique nonlinear behaviors in bilayer graphene towards the development of nonlinear super-resolution THz microscopy and imaging system.

  16. Vector characterization of zero-order terahertz Bessel beams with linear and circular polarizations. (United States)

    Wu, Zhen; Wang, Xinke; Sun, Wenfeng; Feng, Shengfei; Han, Peng; Ye, Jiasheng; Zhang, Yan


    As a kind of special beams, Bessel beams are always a research hot spot in optics due to its non-diffractive and self-healing properties. Here, zero-order terahertz (THz) Bessel beams with linear and circular polarizations are generated by using a THz quarter wave plate and Teflon axicons with different opening angles. By applying a THz digital holographic imaging system, the evolutions of the transverse (E x , E y ) and longitudinal (E z ) electric fields are coherently measured and analyzed during the propagation processes of the THz Bessel beams. The vectorial Rayleigh diffraction integral is used to accurately reproduce the amplitude, phase, and non-diffractive feature of each polarization component for the THz Bessel beams. With varying opening angles of the axicons, the focal spots, diffraction-free ranges, and Gouy phase shifts of the THz Bessel beams are compared and discussed. The experiment and simulation results provide a comprehensive view for exactly understanding peculiar features of THz Bessel beams.

  17. 4F-based optical phase imaging system

    DEFF Research Database (Denmark)


    The invention relates to 4F-based optical phase imaging system and in particular to reconstructing quantitative phase information of an object when using such systems. The invention applies a two-dimensional, complex spatial light modulator (SLM) to impress a complex spatial synthesized modulation...... in addition to the complex spatial modulation impressed by the object. This SLM is arranged so that the synthesized modulation is superimposed with the object modulation and is thus placed at an input plane to the phase imaging system. By evaluating output images from the phase imaging system, the synthesized...... modulation is selected to optimize parameters in the output image which improves the reconstruction of qualitative and quantitative object phase information from the resulting output images....

  18. A review of imaging techniques for systems biology

    Directory of Open Access Journals (Sweden)

    Po Ming J


    Full Text Available Abstract This paper presents a review of imaging techniques and of their utility in system biology. During the last decade systems biology has matured into a distinct field and imaging has been increasingly used to enable the interplay of experimental and theoretical biology. In this review, we describe and compare the roles of microscopy, ultrasound, CT (Computed Tomography, MRI (Magnetic Resonance Imaging, PET (Positron Emission Tomography, and molecular probes such as quantum dots and nanoshells in systems biology. As a unified application area among these different imaging techniques, examples in cancer targeting are highlighted.

  19. A secure online image trading system for untrusted cloud environments. (United States)

    Munadi, Khairul; Arnia, Fitri; Syaryadhi, Mohd; Fujiyoshi, Masaaki; Kiya, Hitoshi


    In conventional image trading systems, images are usually stored unprotected on a server, rendering them vulnerable to untrusted server providers and malicious intruders. This paper proposes a conceptual image trading framework that enables secure storage and retrieval over Internet services. The process involves three parties: an image publisher, a server provider, and an image buyer. The aim is to facilitate secure storage and retrieval of original images for commercial transactions, while preventing untrusted server providers and unauthorized users from gaining access to true contents. The framework exploits the Discrete Cosine Transform (DCT) coefficients and the moment invariants of images. Original images are visually protected in the DCT domain, and stored on a repository server. Small representation of the original images, called thumbnails, are generated and made publicly accessible for browsing. When a buyer is interested in a thumbnail, he/she sends a query to retrieve the visually protected image. The thumbnails and protected images are matched using the DC component of the DCT coefficients and the moment invariant feature. After the matching process, the server returns the corresponding protected image to the buyer. However, the image remains visually protected unless a key is granted. Our target application is the online market, where publishers sell their stock images over the Internet using public cloud servers.

  20. A novel augmented reality system of image projection for image-guided neurosurgery. (United States)

    Mahvash, Mehran; Besharati Tabrizi, Leila


    Augmented reality systems combine virtual images with a real environment. To design and develop an augmented reality system for image-guided surgery of brain tumors using image projection. A virtual image was created in two ways: (1) MRI-based 3D model of the head matched with the segmented lesion of a patient using MRIcro software (version 1.4, freeware, Chris Rorden) and (2) Digital photograph based model in which the tumor region was drawn using image-editing software. The real environment was simulated with a head phantom. For direct projection of the virtual image to the head phantom, a commercially available video projector (PicoPix 1020, Philips) was used. The position and size of the virtual image was adjusted manually for registration, which was performed using anatomical landmarks and fiducial markers position. An augmented reality system for image-guided neurosurgery using direct image projection has been designed successfully and implemented in first evaluation with promising results. The virtual image could be projected to the head phantom and was registered manually. Accurate registration (mean projection error: 0.3 mm) was performed using anatomical landmarks and fiducial markers position. The direct projection of a virtual image to the patients head, skull, or brain surface in real time is an augmented reality system that can be used for image-guided neurosurgery. In this paper, the first evaluation of the system is presented. The encouraging first visualization results indicate that the presented augmented reality system might be an important enhancement of image-guided neurosurgery.