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Artigos de revistas sobre o tema "Terahertz time-domain spectroscopy system"

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Autor: Grafiati

Publicado: 7 de julho de 2024

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1

Hongfei, ZHANG, SU Bo, HE Jingsuo e ZHANG Cunlin. "Ultra-fast terahertz time domain spectroscopy system". Journal of Applied Optics 40, n.º 2 (2019): 41–45. http://dx.doi.org/10.5768/jao201940.0201008.

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2

Ung, Benjamin S. Y., Jining Li, Hungyen Lin, Bernd M. Fischer, Withawat Withayachumnankul e Derek Abbott. "Dual-Mode Terahertz Time-Domain Spectroscopy System". IEEE Transactions on Terahertz Science and Technology 3, n.º 2 (março de 2013): 216–20. http://dx.doi.org/10.1109/tthz.2013.2241427.

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3

Luo, Guofang, Xiaochuan Wei, Ping’an Liu, Wenping Li, Yingze Li, Zhixiang Zhang, Kuan Zhou, Zuoshan Shao e Dong Wang. "Transformer Oil Temperature Variation Based on Terahertz Time-domain Spectroscopy". Journal of Physics: Conference Series 2564, n.º 1 (1 de agosto de 2023): 012012. http://dx.doi.org/10.1088/1742-6596/2564/1/012012.

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Abstract The transmission terahertz time-domain spectroscopy system is used to measure the transformer oil terahertz spectrum at different temperatures, the time and frequency domain, time delay, and refractive information of transformer oil with different temperatures are tested. The terahertz wave of the time-domain delay of transformer oil at different temperatures is obtained, the variation of time-domain delay and refractive index with different temperatures in the terahertz band were calculated and the linear variation trend was fitted.

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4

Shi, Wei, Chengang Dong, Lei Hou, Zhiyang Xing, Qian Sun e Lihao Zhang. "Investigation of aging characteristics in explosive using terahertz time-domain spectroscopy". International Journal of Modern Physics B 33, n.º 24 (30 de setembro de 2019): 1950272. http://dx.doi.org/10.1142/s0217979219502722.

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The terahertz absorption spectrum of the five aging explosive samples (PETN, RDX, HMX, LLM-105 and TATB) was measured and calculated by Terahertz time-domain spectroscopy system (THz-TDS) and air-biased coherent detection system (ZAP-ABCD), respectively. In this paper, compared with the unaging explosive, each aging explosive sample’s terahertz time-domain spectra were obtained and the terahertz absorption spectra were calculated by using Fourier transform and Lambert’s law. The results show that there are several terahertz absorption peaks which were called “fingerprint spectra” for different aging explosive samples in the range of 0.3–6.0 THz spectrum. Meanwhile, the results also show that the locations of the characteristic absorption peaks are not the same. Moreover, the unaging and aging explosive samples have obviously different terahertz absorption spectra.

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Chengzhen Lu, Chengzhen Lu, Chen Liu Chen Liu, Erliang Cui Erliang Cui, Jia Li Jia Li, Wei Liu Wei Liu e Ping Sun Ping Sun. "Analysis on the characteristics of animal tissues based on the Terahertz time domain spectroscopy system". Chinese Optics Letters 10, s1 (2012): S13201–313204. http://dx.doi.org/10.3788/col201210.s13201.

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6

Baron, C. A., e A. Y. Elezzabi. "A 360° angularly ranging time-domain terahertz spectroscopy system". Measurement Science and Technology 19, n.º 6 (19 de maio de 2008): 065602. http://dx.doi.org/10.1088/0957-0233/19/6/065602.

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7

Liu Wenquan, 刘文权, 鲁远甫 Lu Yuanfu, 冯广智 Feng Guangzhi, 龚小竞 Gong Xiaojing, 杨珺 Yang Jun, 张艳东 Zhang Yandong e 金雷 Jin Lei. "Research Progress of Rapid Scan Terahertz Time Domain Spectroscopy System". Laser & Optoelectronics Progress 48, n.º 12 (2011): 123001. http://dx.doi.org/10.3788/lop48.123001.

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8

Molis, G., R. Adomavičius, A. Krotkus, K. Bertulis, L. Giniūnas, J. Pocius e R. Danielius. "Terahertz time-domain spectroscopy system based on femtosecond Yb:KGW laser". Electronics Letters 43, n.º 3 (2007): 190. http://dx.doi.org/10.1049/el:20073168.

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9

Guan, Yu, Manabu Yamamoto, Toshiyuki Kitazawa, Saroj R. Tripathi, Kei Takeya e Kodo Kawase. "A Concealed Barcode Identification System Using Terahertz Time-domain Spectroscopy". Journal of Infrared, Millimeter, and Terahertz Waves 36, n.º 3 (11 de dezembro de 2014): 298–311. http://dx.doi.org/10.1007/s10762-014-0128-2.

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10

Globisch, Björn, Roman J. B. Dietz, Thorsten Göbel, Martin Schell, Werner Bohmeyer, Ralf Müller e Andreas Steiger. "Absolute terahertz power measurement of a time-domain spectroscopy system". Optics Letters 40, n.º 15 (24 de julho de 2015): 3544. http://dx.doi.org/10.1364/ol.40.003544.

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Han, Sang-Pil, Hyunsung Ko, Namje Kim, Han-Cheol Ryu, Chul Wook Lee, Young Ahn Leem, Donghun Lee et al. "Optical fiber-coupled InGaAs-based terahertz time–domain spectroscopy system". Optics Letters 36, n.º 16 (8 de agosto de 2011): 3094. http://dx.doi.org/10.1364/ol.36.003094.

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12

Im, Kwang Hee, David K. Hsu, Chien Ping Chiou e Daniel J. Barnard. "T-Ray NDE Inspections on the Fiber Direction of Thermoplastic PPS-Based CFRP Composites". Advanced Materials Research 650 (janeiro de 2013): 253–57. http://dx.doi.org/10.4028/www.scientific.net/amr.650.253.

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Terahertz ray (T-ray) imaging has been emerged as one of the most promising new powerful nondestructive evaluation (NDE) techniques, and new application systems are under processing development for the area applications. The terahertz time domain spectroscopy (THz TDS) can be considered as a useful tool using general non-conducting materials; however it is quite limited to conducting materials. In this study, a new time-domain spectroscopy system was utilized for detecting and evaluating layup effect and flaw in FRP composite laminates. In order to solve various material properties, the index of refraction (n) and the absorption coefficient (α) are derived in reflective and transmission configuration using the terahertz time domain spectroscopy. However, the T-ray is limited in order to penetrate a conducting material to some degree. So, investigation of terahertz time domain spectroscopy (THz TDS) was made and reflection and transmission configurations were studied for a 48-ply thermoplastic PPS (poly-phenylene sulfide)-based CFRP solid laminate.

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13

Verona, Ivan Cedrick Malaluan, Alexander De los Reyes, Hannah Bardolaza e Elmer Estacio. "Terahertz Quasi-Time Domain Spectroscopy using a 808nm multimode diode laser". Journal of Physics and Its Applications 5, n.º 2 (25 de maio de 2023): 58–61. http://dx.doi.org/10.14710/jpa.v5i2.17945.

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We report on a terahertz quasi-time domain spectroscopy (QTDS) system based on a low-cost continuous wave multimode diode laser. Commercially available low-temperature grown gallium arsenide (LT-GaAs) based photoconductive antennas (PCAs) with spiral and dipole configurations were used as emitter and detector, respectively. Terahertz pulses spaced at approximately 55 ps with a bandwidth of 400 GHz were obtained. Parametric measurements of the terahertz peak-to-peak intensity were performed by varying the injection current and temperature while maintaining incident laser power. The highest peak-to-peak intensity was obtained at 170mA injection current and 20° C temperature settings. The change in the THz peak-to-peak intensity is attributed to the mode hopping characteristics of the device which in turn, is dependent on injection current and temperature.

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14

Yang, Boqin, Hu Deng, Quancheng Liu, LinYu Chen, Liang Xiong, Zhixiang Wu, Weiwei Qu e Liping Shang. "A Contactless Liquor Level Detection Method Using Terahertz Time-Domain Spectroscopy". Journal of Sensors 2021 (27 de outubro de 2021): 1–7. http://dx.doi.org/10.1155/2021/3396439.

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In this paper, we proposed the terahertz technique to measure the liquid level of Chinese liquor in sealed pots. We analyzed the transmission process of terahertz pulse in the sealed pots and established a model of the relationship between terahertz pulse interval and liquor level. The measurement results are in good agreement with the theoretical model. The results show that the terahertz technique can realize the high precision measurement of liquor level. The absolute and relative errors are less than ±40 μm and 0.014%, respectively. In addition, we also evaluated the influence of dewdrop on the measurement accuracy. The results show that dewdrop only leads to a deviation of 18 μm. The results prove the value of terahertz technology in the field of liquid level monitoring.

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Yahyapour, Milad, Angelika Jahn, Katja Dutzi, Thomas Puppe, Patrick Leisching, Bernhard Schmauss, Nico Vieweg e Anselm Deninger. "Fastest Thickness Measurements with a Terahertz Time-Domain System based on Electronically Controlled Optical Sampling". Applied Sciences 9, n.º 7 (27 de março de 2019): 1283. http://dx.doi.org/10.3390/app9071283.

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We apply a fast terahertz time-domain spectroscopy (TDS) system based on electronically controlled optical sampling (ECOPS) to contact-free thickness gauging. Our setup achieves a measurement speed of 1600 terahertz pulse traces per second, which—to our knowledge—represents the fastest thickness measurement performed with any terahertz system to-date. Using a silicon wafer as a test sample, we compare data of the ECOPS experiment to results obtained with a conventional terahertz TDS system and a mechanical micrometer gauge. We show that all systems provide consistent results within the measurement accuracy. Moreover, we perform thickness measurements of a rapidly moving sample and characterize the ECOPS setup with respect to time-domain dynamic range, signal-to-noise ratio, and spectral properties.

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16

Mamrashev, Alexander, Fedor Minakov, Nazar Nikolaev e Valery Antsygin. "Terahertz Time-Domain Polarimetry for Principal Optical Axes of Anisotropic Crystals". Photonics 8, n.º 6 (10 de junho de 2021): 213. http://dx.doi.org/10.3390/photonics8060213.

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We propose a method for measuring the terahertz properties for two principal optical axes of anisotropic crystals without optical activity using terahertz time-domain spectroscopy (THz-TDS). The method put forward in this paper utilizes the inherent polarization sensitivity of the THz-TDS electro-optic detection system. We demonstrate the practical application of the method by measuring the temperature dependence of the refractive index and the absorption coefficient of a lithium triborate crystal for three optical axes.

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17

Chady, Tomasz, e Krzysztof Gorący. "Thickness identification of nonconductive coatings using terahertz time domain spectroscopy system". International Journal of Applied Electromagnetics and Mechanics 59, n.º 4 (21 de março de 2019): 1511–17. http://dx.doi.org/10.3233/jae-171063.

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18

Ospald, Frank, Wissem Zouaghi, René Beigang, Carsten Matheis, Joachim Jonuscheit, Benoit Recur, Jean-Paul Guillet et al. "Aeronautics composite material inspection with a terahertz time-domain spectroscopy system". Optical Engineering 53, n.º 3 (16 de dezembro de 2013): 031208. http://dx.doi.org/10.1117/1.oe.53.3.031208.

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19

Brahm, Anika, Annika Wilms, Roman J. B. Dietz, Thorsten Göbel, Martin Schell, Gunther Notni e Andreas Tünnermann. "Multichannel terahertz time-domain spectroscopy system at 1030 nm excitation wavelength". Optics Express 22, n.º 11 (21 de maio de 2014): 12982. http://dx.doi.org/10.1364/oe.22.012982.

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20

Watanabe, Shinichi, e Ryo Shimano. "Compact terahertz time domain spectroscopy system with diffraction-limited spatial resolution". Review of Scientific Instruments 78, n.º 10 (outubro de 2007): 103906. http://dx.doi.org/10.1063/1.2796941.

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21

Merghem, K., S. F. Busch, F. Lelarge, M. Koch, A. Ramdane e J. C. Balzer. "Terahertz Time-Domain Spectroscopy System Driven by a Monolithic Semiconductor Laser". Journal of Infrared, Millimeter, and Terahertz Waves 38, n.º 8 (30 de maio de 2017): 958–62. http://dx.doi.org/10.1007/s10762-017-0401-2.

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22

Liu, Li Ping, Li Shen, Mao Jiang Song, Fei Yang, Feng Han e Peng Fei Hu. "Adjusting Methods of the Off-Axis Parabolic Mirror in Terahertz Time Domain System". Applied Mechanics and Materials 713-715 (janeiro de 2015): 2119–22. http://dx.doi.org/10.4028/www.scientific.net/amm.713-715.2119.

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According to the geometric optics, off-axis parabolic mirrors are used in terahertz time domain system for focusing the terahertz pulse. Theoretically, the focus of the parabolic reflector to eliminate the effects of spherical aberration, but a very high sensitivity to its optical axis misalignment, subtle misalignment will reduce the focal spot quality and therefore the need for precision optical axis adjustment is important. This article discusses terahertz time-domain spectroscopy system adjustment method in four off-axis parabolic mirror, after many experiments have proved feasible. In this work, two optical path adjustment methods were analyzed. The first approach is based on adjustment of spot shape from collimation and focus. In the second method, depend on the principle that the incident light path is different from reflected light path in parabolic cross section. Through testing this two methods have been proved feasible.

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23

Cai Jiahua, 才家华, 张保龙 Zhang Baolong, 耿春艳 Geng Chunyan, 郝思博 Hao Sibo, 陈赛 Chen Sai e 吴晓君 Wu Xiaojun. "铌酸锂强场太赫兹非线性时域光谱系统". Chinese Journal of Lasers 50, n.º 17 (2023): 1714012. http://dx.doi.org/10.3788/cjl230435.

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24

Kolpatzeck, Kevin, Xuan Liu, Lars Häring, Jan C. Balzer e Andreas Czylwik. "Ultra-High Repetition Rate Terahertz Time-Domain Spectroscopy for Micrometer Layer Thickness Measurement". Sensors 21, n.º 16 (10 de agosto de 2021): 5389. http://dx.doi.org/10.3390/s21165389.

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Terahertz time-domain spectroscopy systems driven by monolithic mode-locked laser diodes (MLLDs) exhibit bandwidths exceeding 1 THz and a peak dynamic range that can compete with other state-of-the-art systems. Their main difference compared to fiber-laser-driven systems is their ultra-high repetition rate of typically dozens of GHz. This makes them interesting for applications where the length of the terahertz path may not be precisely known and it enables the use of a very short and potentially fast optical delay unit. However, the phase accuracy of the system is limited by the accuracy with which the delay axes of subsequent measurements are synchronized. In this work, we utilize an all-fiber approach that uses the optical signal from the MLLD in a Mach–Zehnder interferometer to generate a reference signal that we use to synchronize the detected terahertz signals. We demonstrate transmission-mode thickness measurements of stacked layers of 17μm thick low-density polyethylene (LDPE) films.

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25

Wang, Jingrong, Zhuoyong Zhang, Zhenwei Zhang, Yuhong Xiang e Peter de B. Harrington. "THz-TDS combined with a fuzzy rule-building expert system applied to the identification of official rhubarb samples". Anal. Methods 6, n.º 19 (2014): 7695–702. http://dx.doi.org/10.1039/c4ay00555d.

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Jin, Z., A. Wada, J. H. Shin, N. Yugami e R. Kodama. "A Single-shot Terahertz Time-domain Spectroscopy Instrument for Intense Laser System". Journal of Physics: Conference Series 688 (março de 2016): 012040. http://dx.doi.org/10.1088/1742-6596/688/1/012040.

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Nakanishi, Atsushi, Yoichi Kawada, Takashi Yasuda, Koichiro Akiyama e Hironori Takahashi. "Terahertz time domain attenuated total reflection spectroscopy with an integrated prism system". Review of Scientific Instruments 83, n.º 3 (março de 2012): 033103. http://dx.doi.org/10.1063/1.3692743.

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Liu, Liping, Pengfei Hu, Fei Yang e Maojiang Song. "Application of terahertz time-domain spectroscopy combined with support vector machine to determine tea and pesticide samples". Materials Express 10, n.º 10 (31 de outubro de 2020): 1646–53. http://dx.doi.org/10.1166/mex.2020.1820.

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The transmission-type terahertz spectrometer can rapidly identify samples in a nondestructive and non-contact way. This method can also identify the important components in these samples. To test the application of the Terahertz Time-Domain Spectrometer (THz-TDS), our work focused on the identifying isomers of catechin (an important compound in tea) and the difference among green, black, and white tea. We detected the properties of pesticide residues such as thiamethoxam. Thiamethoxam with similar structure was added into the tea samples to test the resolution of the system. In this work, Support Vector Machine (SVM) and K-means clustering algorithms were employed to identify green, white, and black tea. The terahertz plus identification spectra of these structures were obtained from the experiment. The results demonstrate that THz-TDS has strong physical recognition abilities and supports the theory and application of terahertz spectrum and terahertz response.

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Ren, Xiaozhen, Yanwen Bai e Yuying Jiang. "Hybrid Sparsity Model for Fast Terahertz Imaging". Micromachines 12, n.º 10 (29 de setembro de 2021): 1181. http://dx.doi.org/10.3390/mi12101181.

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In order to shorten the long-term image acquisition time of the terahertz time domain spectroscopy imaging system while ensuring the imaging quality, a hybrid sparsity model (HSM) is proposed for fast terahertz imaging in this paper, which incorporates both intrinsic sparsity prior and nonlocal self-similarity constraints in a unified statistical model. In HSM, a weighted exponentiation shift-invariant wavelet transform is introduced to enhance the sparsity of the terahertz image. Simultaneously, the nonlocal self-similarity by means of the three-dimensional sparsity in the transform domain is exploited to ensure high-quality terahertz image reconstruction. Finally, a new split Bregman-based iteration algorithm is developed to solve the terahertz imaging model more efficiently. Experiments are presented to verify the effectiveness of the proposed approach.

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Liu, Xuan, Kevin Kolpatzeck, Lars Häring, Jan C. Balzer e Andreas Czylwik. "Wideband Beam Steering Concept for Terahertz Time-Domain Spectroscopy: Theoretical Considerations". Sensors 20, n.º 19 (28 de setembro de 2020): 5568. http://dx.doi.org/10.3390/s20195568.

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Photonic true time delay beam steering on the transmitter side of terahertz time-domain spectroscopy (THz TDS) systems requires many wideband variable optical delay elements and an array of coherently driven emitters operating over a huge bandwidth. We propose driving the THz TDS system with a monolithic mode-locked laser diode (MLLD). This allows us to use integrated optical ring resonators (ORRs) whose periodic group delay spectra are aligned with the spectrum of the MLLD as variable optical delay elements. We show by simulation that a tuning range equal to one round-trip time of the MLLD is sufficient for beam steering to any elevation angle and that the loss introduced by the ORR is less than 0.1 dB. We find that the free spectral ranges (FSRs) of the ORR and the MLLD need to be matched to 0.01% so that the pulse is not significantly broadened by third-order dispersion. Furthermore, the MLLD needs to be frequency-stabilized to about 100 MHz to prevent significant phase errors in the terahertz signal. We compare different element distributions for the array and show that a distribution according to a Golomb ruler offers both reasonable directivity and no grating lobes from 50 GHz to 1 THz.

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Xin, Yu, Hassan Yousefi Oderji, Ran Hai e Hong Bin Ding. "Molecular Dynamics Simulation on Terahertz Spectra of Methamphetamine Hydrochloride". Advanced Materials Research 760-762 (setembro de 2013): 35–39. http://dx.doi.org/10.4028/www.scientific.net/amr.760-762.35.

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Methamphetamine hydrochloride crystal (trade name Methedrine) that is one of the illegal drugs used as a stimulant to the nervous system has been considered to be detected by T-ray via the terahertz time-domain spectroscopy (THz-TDS). In this research, we simulated the THz spectra of Methedrine by molecular dynamics methods for the first time. The terahertz spectra at temperatures 78.4K, 200K, 294K and 400K in the frequency range of 10-100cm-1 were investigated, which exhibited the variation of spectra position and intensity with increasing temperature. Firstly, we used DL_POLY simulation package to obtain the instantaneous values of the dipole moment. Subsequently, the intensities of THz vibrational modes were obtained by the Fourier transform of the autocorrelation function of the dipole moment. The results showed our theoretical calculation by molecular dynamics simulations got a good consistency with available experimental spectroscopy. These are useful to determine the best conditions of temperature at which the terahertz time-domain spectroscopy of Methedrine results a highly informative spectrum.

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Im, Kwang-Hee, David K. Hsu, Chien-Ping Chiou, Daniel J. Barnard, Jong-An Jung e In-Young Yang. "Terahertz Wave Approach and Application on FRP Composites". Advances in Materials Science and Engineering 2013 (2013): 1–10. http://dx.doi.org/10.1155/2013/563962.

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Terahertz (THz) applications have emerged as one of the most new powerful nondestructive evaluation (NDE) techniques. A new T-ray time-domain spectroscopy system was utilized for detecting and evaluating orientation influence in carbon fiber-reinforced plastics (CFRPs) composite laminates. Investigation of terahertz time-domain spectroscopy (THz-TDS) was made, and reflection and transmission configurations were studied as a nondestructive evaluation technique. Here, the CFRP composites derived their excellent mechanical strength, stiffness, and electrical conductivity from carbon fibers. Especially, the electrical conductivity of the CFRP composites depends on the direction of unidirectional fibers since carbon fibers are electrically conducting while the epoxy matrix is not. In order to solve various material properties, the index of refraction (n) and the absorption coefficient (α) are derived in reflective and transmission configurations using the terahertz time-domain spectroscopy. Also, for a 48-ply thermoplastic polyphenylene-sulfide-(PPS-) based CFRP solid laminate and nonconducting materials, the terahertz scanning images were made at the angles ranged from0°to180°with respect to the nominal fiber axis. So, the images were mapped out based on the electrical field (E-field) direction in the CFRP solid laminates. It is found that the conductivity (σ) depends on the angles of the nominal axis in the unidirectional fiber.

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Degl’Innocenti, R., Y. Lu, L. L. Hale, A. M. Zaman, S. J. Addamane, I. Brener e O. Mitrofanov. "THz Near-field spectroscopy of metamaterial resonators". Journal of Physics: Conference Series 2725, n.º 1 (1 de março de 2024): 012002. http://dx.doi.org/10.1088/1742-6596/2725/1/012002.

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Abstract Terahertz near-field spectroscopy is a powerful technique for the investigation of metamaterial resonators with subwavelength resolution. Here, we used an a-SNOM THz time domain spectroscopic system for the direct study of all the modes supported by individual D-split ring resonators, their E-field distributions and relative Q factors. A cross-polarized excitation and detection technique is also demonstrated, yielding a modes’ mapping by the resonators with unprecedented resolution and sharpness.

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Khoroshailo, Yu Ye, N. Ya Zaichenko e О. B. Zaichenko. "Improvement of spectroscopic method for determining refractive index of filament sample material for 3D printing in terahertz range". Radiotekhnika, n.º 209 (24 de junho de 2022): 215–25. http://dx.doi.org/10.30837/rt.2022.2.209.22.

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The article considers the topical problem of non-destructive filament defectoscopy for 3D printing. The subject of the research is the process of determining the refractive index of the filament material for 3D printing taking into account the reflections from sample opposite walls, which is studied by terahertz spectroscopy in the time domain. Reflections from opposite walls are called the Fabry-Perot effect, and interference members resulting from reflections from walls are traditionally taken into account by summation and represented as a series. The disadvantage of the model in the form of a simple summation is the rejection of the members of the series above the fourth, which leads to inaccuracies in the model. The main problem with terahertz spectroscopy and this study in particular is the contradiction between the rapid development of terahertz spectroscopy and the slow development of models used in terahertz spectroscopy, while the adjacent microwave region has a set of ready-made models. Models based on the description of a standing wave in the microwave tract with refinements, transferred to a new region of terahertz spectroscopy in the time domain. The scientific novelty lies in increasing accuracy by taking into account previously unaccounted for interference members. The analogy between the Fabry-Perot effect used in terahertz spectroscopy and the reflections in a microwave multiprobe multimeter suggested the following recommendations. First, because the phase distance between the sensors in the microwave multimeter is similar to the thickness of the sample in terahertz spectroscopy, therefore, there was choosen such a sample thickness that the interference members are compensated, and secondly, instead of simple sum up it is possibility apply algorithmic processing, the condition for this is the existence in addition to the main signal in the time domain of the recorded echo signals of much smaller amplitude, therefore, one can build a system of equations and by solving it to determine the desired refractive index parameters of the filament sample material.

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Weber, Stefan, Lukas Liebelt, Jens Klier, Tobias Pfeiffer, Daniel Molter, Frank Ellrich, Joachim Jonuscheit e Georg Von Freymann. "Influence of System Performance on Layer Thickness Determination Using Terahertz Time-Domain Spectroscopy". Journal of Infrared, Millimeter, and Terahertz Waves 41, n.º 4 (28 de janeiro de 2020): 438–49. http://dx.doi.org/10.1007/s10762-020-00669-3.

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LIU Quan-cheng, 刘泉澄, 邓. 琥. DENG Hu e 尚丽平 SHANG Li-ping. "Quantitative Investigation of α/β HMX Based on Terahertz Time Domain Spectroscopy System". Chinese Journal of Luminescence 37, n.º 5 (2016): 631–36. http://dx.doi.org/10.3788/fgxb20163705.0631.

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Mølvig, Bjørn Hübschmann, Thorsten Bæk, Jie Ji, Peter Bøggild, Simon Jappe Lange e Peter Uhd Jepsen. "Terahertz Cross-Correlation Spectroscopy and Imaging of Large-Area Graphene". Sensors 23, n.º 6 (21 de março de 2023): 3297. http://dx.doi.org/10.3390/s23063297.

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We demonstrate the use of a novel, integrated THz system to obtain time-domain signals for spectroscopy in the 0.1–1.4 THz range. The system employs THz generation in a photomixing antenna excited by a broadband amplified spontaneous emission (ASE) light source and THz detection with a photoconductive antenna by coherent cross-correlation sampling. We benchmark the performance of our system against a state-of-the-art femtosecond-based THz time-domain spectroscopy system in terms of mapping and imaging of the sheet conductivity of large-area graphene grown by chemical vapor deposition (CVD) and transferred to a PET polymer substrate. We propose to integrate the algorithm for the extraction of the sheet conductivity with the data acquisition, thereby enabling true in-line monitoring capability of the system for integration in graphene production facilities.

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KARPOWICZ, NICHOLAS, JIANMING DAI, X. C. ZHANG, LIANGLIANG ZHANG e CUNLIN ZHANG. "RECENT DEVELOPMENTS IN BROADBAND TERAHERTZ SPECTROSCOPY". International Journal of High Speed Electronics and Systems 18, n.º 04 (dezembro de 2008): 1005–12. http://dx.doi.org/10.1142/s0129156408005953.

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Terahertz time-domain measurements using air as the emission and detection medium are shown to enable broadband spectroscopy with continuous coverage of the entire terahertz band, from 0.1 to over 10 THz. It is shown that the unique properties of using a gaseous medium allow for excellent phase matching without interruptions from crystalline phonon modes or antenna resonant structures from conventional solid state emitters and sensors, allowing the full bandwidth of the laser pulse to be used. It is also shown that the limiting factor on the system bandwidth is the temporal profile of the probe pulse used for detection, and how modification of this profile can further enhance the detection bandwidth.

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39

Singh, Khushboo, Aparajita Bandyopadhyay, Karl Bertling, Yah Leng Lim, Tim Gillespie, Dragan Indjin, Lianhe Li et al. "Comparison of Physical and System Factors Impacting Hydration Sensing in Leaves Using Terahertz Time-Domain and Quantum Cascade Laser Feedback Interferometry Imaging". Sensors 23, n.º 5 (2 de março de 2023): 2721. http://dx.doi.org/10.3390/s23052721.

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To reduce the water footprint in agriculture, the recent push toward precision irrigation management has initiated a sharp rise in photonics-based hydration sensing in plants in a non-contact, non-invasive manner. Here, this aspect of sensing was employed in the terahertz (THz) range for mapping liquid water in the plucked leaves of Bambusa vulgaris and Celtis sinensis. Two complementary techniques, broadband THz time-domain spectroscopic imaging and THz quantum cascade laser-based imaging, were utilized. The resulting hydration maps capture the spatial variations within the leaves as well as the hydration dynamics in various time scales. Although both techniques employed raster scanning to acquire the THz image, the results provide very distinct and different information. Terahertz time-domain spectroscopy provides rich spectral and phase information detailing the dehydration effects on the leaf structure, while THz quantum cascade laser-based laser feedback interferometry gives insight into the fast dynamic variation in dehydration patterns.

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40

Jiao Yufeng, 焦宇峰, 郭素杰 Guo Sujie, 孔德胤 Kong Deyin e 阮存军 Ruan Cunjun. "连续波频域太赫兹光谱系统的研究". Chinese Journal of Lasers 49, n.º 19 (2022): 1914002. http://dx.doi.org/10.3788/cjl202249.1914002.

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Su, Hong, Zesong Zheng, Zhisheng Yu, Shiping Feng, Huiting Lan, Shixing Wang, Min Zhang, Ling Li e Huawei Liang. "Optically Controlling Broadband Terahertz Modulator Based on Layer-Dependent PtSe2 Nanofilms". Nanomaterials 13, n.º 5 (21 de fevereiro de 2023): 795. http://dx.doi.org/10.3390/nano13050795.

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In this paper, we propose an optically controlling broadband terahertz modulator of a layer-dependent PtSe2 nanofilm based on a high-resistance silicon substrate. Through optical pump and terahertz probe system, the results show that compared with 6-, 10-, and 20-layer films, a 3-layer PtSe2 nanofilm has better surface photoconductivity in the terahertz band and has a higher plasma frequency ωp of 0.23 THz and a lower scattering time τs of 70 fs by Drude–Smith fitting. By the terahertz time-domain spectroscopy system, the broadband amplitude modulation of a 3-layer PtSe2 film in the range of 0.1–1.6 THz was obtained, and the modulation depth reached 50.9% at a pump density of 2.5 W/cm2. This work proves that PtSe2 nanofilm devices are suitable for terahertz modulators.

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42

Qiang Xu, 徐强, 苏强 Qiang Su, 鲁丹 Dan Lu, 张楠 Nan Zhang, 张杨 Yang Zhang e 刘伟伟 Weiwei Liu. "Review of Terahertz Time-Domain Spectroscopy Systems Based on Laser Filament". Chinese Journal of Lasers 46, n.º 6 (2019): 0614010. http://dx.doi.org/10.3788/cjl201946.0614010.

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Liu, Zhe, Xian Li, Fei Heng Yue, Lu Feng, Jin Hui Cai, Xu Sheng Kang e Ping Jie Huang. "Research of Beta-Endosulfan Based on THz Time-Domain Spectroscopy". Advanced Materials Research 718-720 (julho de 2013): 1060–65. http://dx.doi.org/10.4028/www.scientific.net/amr.718-720.1060.

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THz spectral properties between 0.2-1.5THz of beta-endosulfan, one of the persistent organic pollutants (POPs), are investigated based on the THz time domain system. Part of the characteristic absorption peaks are theoretically analyzed by Dmol3 modular program. The experimental results show that the average refractive index of beta-endosulfan in the THz waveband is about 1.005 and characteristic absorption peaks exist at 0.67, 0.80, 1.03, 1.14, 1.26 and 1.46THz. The absorption peaks at 0.67THz and 1.03THz have a good match with the theoretic absorption peak positions which appear at 0.72THz and 1.07THz calculated by Dmol3. The peaks at 0.67THz and 1.03THz may be caused by the torsion in B and C direction of beta-endosulfan crystal lattice, along with the translation in A direction. Compared with the experimental results of alpha-endosulfan, it can be seen clearly that these two isomers have completely different absorption peaks. For further it indicates that terahertz time domain spectroscopy (THz-TDS) has great application value in identifying isomers.

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44

Chang, Tianying, Xiansheng Zhang e Hong-Liang Cui. "Terahertz Dielectric Spectroscopic Analysis of Polypropylene Aging Caused by Exposure to Ultraviolet Radiation". Polymers 11, n.º 12 (3 de dezembro de 2019): 2001. http://dx.doi.org/10.3390/polym11122001.

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Terahertz dielectric spectroscopy is shown to be an effective tool for bench-marking ultraviolet aging of polypropylene. In this, thin-film polypropylene samples exposed to standard artificial ultraviolet radiation in accelerated aging from 1 day to 30 days are closely monitored by a terahertz time-domain spectroscopy system and analyzed using an effective data processing method. It is found that the terahertz absorption of the polypropylene samples is generally weak and the terahertz dielectric constant varies slightly though discernibly during the aging process, with the refractive index decreasing slightly with increasing length of ultraviolet exposure. Nonetheless, the rate of variation of the polypropylene refractive index with increasing terahertz frequency exhibits a drastic inflection around the 15-days aging point and the rate changes suddenly from positive value to negative value. Based on this prominent and consistent THz dielectric spectroscopic feature of the aging process, an efficient judging criterion is established to distinguish the early-term, mid-term, and late-term phases as well as the degree of polypropylene ultraviolet aging, corresponding to the fundamental transformation of the polymer material from a nonpolar to a polar substance at a critical level of oxidation induced by ultraviolet radiation.

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TU Shan, 涂闪, 张文涛 ZHANG Wen-tao, 熊显名 XIONG Xian-ming e 陈涛 CHEN Tao. "Principal Component Analysis for Transgenic Cotton Seeds Based on Terahertz Time Domain Spectroscopy System". ACTA PHOTONICA SINICA 44, n.º 4 (2015): 430001. http://dx.doi.org/10.3788/gzxb20154404.0430001.

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Brenner, Carsten, Martin Hofmann, Maik Scheller, Mohammad Khaled Shakfa, Martin Koch, Iván Cámara Mayorga, Andreas Klehr, Götz Erbert e Günther Tränkle. "Compact diode-laser-based system for continuous-wave and quasi-time-domain terahertz spectroscopy". Optics Letters 35, n.º 23 (17 de novembro de 2010): 3859. http://dx.doi.org/10.1364/ol.35.003859.

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Jin, Z., S. Wakamatsu, T. J. Zhang, H. Kataoka, M. Takita, N. Yugami, T. Hosokai e R. Kodama. "Distortion reduction by introducing an initial birefringence in intense terahertz time-domain spectroscopy system". Journal of Physics D: Applied Physics 50, n.º 25 (5 de junho de 2017): 255602. http://dx.doi.org/10.1088/1361-6463/aa71fd.

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Pačebutas, V., A. Bičiūnas, S. Balakauskas, A. Krotkus, G. Andriukaitis, D. Lorenc, A. Pugžlys e A. Baltuška. "Terahertz time-domain-spectroscopy system based on femtosecond Yb:fiber laser and GaBiAs photoconducting components". Applied Physics Letters 97, n.º 3 (19 de julho de 2010): 031111. http://dx.doi.org/10.1063/1.3458826.

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Picollo, Marcello, Kaori Fukunaga e Julien Labaune. "Obtaining noninvasive stratigraphic details of panel paintings using terahertz time domain spectroscopy imaging system". Journal of Cultural Heritage 16, n.º 1 (janeiro de 2015): 73–80. http://dx.doi.org/10.1016/j.culher.2014.01.006.

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Chen, Si, Chao Yan, Bin Luo e Bin Yang. "Study on the Terahertz Time Domain Spectrum of P-Chloroaniline". Advanced Materials Research 441 (janeiro de 2012): 741–45. http://dx.doi.org/10.4028/www.scientific.net/amr.441.741.

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P-chloroaniline is one of the most important azo dye intermediates. It is a highly desired research on the identification of P-chloroaniline. Terahertz time domain spectroscopy (THz-TDS) is sensitive to the molecule structure of compound. In this paper, the spectra of P-chloroaniline located at the region from 0.1 to 3 THz were tested by THz-TDS system, and then the geometry structure of p-chloroaniline at the range of 0 THz to 10 THz was optimized, resonance frequency was calculated by Gussian03 software based on the density functional theory (DFT). The results showed that the absorbance peaks at 1.96 THz and 2.20 THz were caused by the hydrogen bonding force or crystal phonon mode, and suggested that it is feasible to identify P-chloroaniline by THz-TDS, which is of great value to the examination of banned azo dyes in the future.

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