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Wang Z, Li X, Wang Q, Gong C, Liu W. Terahertz super-resolution imaging based on a confocal waveguide and a slider-crank scanning mechanism. OPTICS EXPRESS 2023; 31:19945-19957. [PMID: 37381399 DOI: 10.1364/oe.492266] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/03/2023] [Accepted: 05/15/2023] [Indexed: 06/30/2023]
Abstract
Due to the limitation of Abbe diffraction limit, the traditional terahertz (THz) continuous wave imaging methods based on lenses or mirrors are difficult to achieve super-resolution. Here we present a confocal waveguide scanning method for THz reflective super-resolution imaging. In the method, a low loss THz hollow waveguide is used to replace the traditional terahertz lens or parabolic mirror. Through optimizing the size of the waveguide, we can achieve far field subwavelength focusing at 0.1THz and achieve super-resolution terahertz imaging. In addition, a slider-crank high-speed scanning mechanism is used in the scanning system, and the imaging speed is more than 10 times faster than the traditional step scanning system based on linear guides.
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He M, Zeng J, Zhang X, Zhu X, Jing C, Chang C, Shi Y. Transmission and imaging characteristics of flexible gradually tapered waveguide at 0.3 THz. OPTICS EXPRESS 2021; 29:8430-8440. [PMID: 33820290 DOI: 10.1364/oe.419506] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/14/2021] [Accepted: 02/22/2021] [Indexed: 06/12/2023]
Abstract
Flexible gradually tapered metal waveguides (GTMWs) are fabricated by an inner plating silver film in a polycarbonate (PC) capillary for the transmission and imaging at 0.3 THz. It was demonstrated theoretically and experimentally that GTMWs have lower transmission losses and smaller additional losses of bending, comparing with thin constant bore metal waveguides (CBMWs). Measured losses of 1.95 dB and 2.45 dB were obtained for a 1 m long GTMW with bore size varying from 2.6 mm to 1.6 mm under straight and one circle bending configuration. Measured losses were 4.48 dB/m and 7.78 dB/m for 1.6 mm bore CBMW under the same straight and bend configurations. Owing to higher energy concentration at the output, a larger penetration ability of output wave can be achieved by GTMW, which is beneficial for imaging application. A scanning imaging system was established using fabricated waveguides as the probes. Measured results show that the air slits of the order of wavelength can be clearly distinguished. An imaging system with a GTMW probe also has better performances due to lower bending loss and improved coupling efficiency.
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Achouri IE, Rhoden A, Hudon S, Gosselin R, Simard JS, Abatzoglou N. Non-invasive detection technologies of solid foreign matter and their applications to lyophilized pharmaceutical products: A review. Talanta 2021; 224:121885. [PMID: 33379094 DOI: 10.1016/j.talanta.2020.121885] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/29/2020] [Revised: 10/15/2020] [Accepted: 10/19/2020] [Indexed: 01/28/2023]
Abstract
Good Manufacturing Practice Regulations, under the Food and Drug Administration (FDA), stipulate that all pharmaceutical products must be free of any contaminants, including, namely, any foreign solid objects. Lyophilization is a common manufacturing method that consists of several steps where foreign materials may enter the product. The presence of unintended particles in freeze drying, which will herein be referred to under the term 'Lyophilization', is of great concern to the authorities responsible for drug safety and effectiveness. In the pharmaceutical industry, presently, the inspection of lyophilized products for foreign matter particulates relies on visual inspection where only the outer surface of the lyophilized cake is visible. This review is motivated by the need for new control strategies for foreign matter (FM) detection in lyophilized products; more specifically, it assesses the reliability of non-destructive technologies for FM detection in dried samples. Emerging technologies applied in other industries, such as various types of spectroscopies and imaging (e.g. chemical, X-ray, ultrasound, thermal and terahertz), are evaluated based on compatibility with the intended application, with identification of the possible technical challenges.
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Affiliation(s)
- Inès E Achouri
- Département de Génie Chimique et de Génie Biotechnologique, Université de Sherbrooke, Sherbrooke, QC, Canada.
| | - Alan Rhoden
- Pfizer USA, 100 route 206 North, Peapack, NJ, 07977, USA
| | - Sophie Hudon
- Pfizer Canada, 17300 route transcanadienne, Kirkland, QC, H9J 2M5, Canada
| | - Ryan Gosselin
- Département de Génie Chimique et de Génie Biotechnologique, Université de Sherbrooke, Sherbrooke, QC, Canada
| | | | - Nicolas Abatzoglou
- Département de Génie Chimique et de Génie Biotechnologique, Université de Sherbrooke, Sherbrooke, QC, Canada
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Wang Y, Wang Y, Xu D, Wu L, Wang G, Jiang B, Yu T, Chang C, Chen T, Yao J. Interference elimination based on the inversion method for continuous-wave terahertz reflection imaging. OPTICS EXPRESS 2020; 28:21926-21939. [PMID: 32752464 DOI: 10.1364/oe.396611] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/01/2020] [Accepted: 06/30/2020] [Indexed: 05/23/2023]
Abstract
We propose a novel approach based on the inversion method to eliminate interference in the continuous-wave (CW) terahertz (THz) reflection imaging. Through the study on the imaging window of the CW-THz reflection imaging with the interference mechanism, inverse processing is introduced to realize the interference elimination. Based on the theoretical calculation, high resistivity float-zone silicon (HRFZ-Si) with high refractive index is selected as the imaging window to improve the dynamic range of the THz image. The interference elimination method is verified experimentally by a CW-THz reflection imaging system based on a THz quantum cascade laser (QCL) lasing at 4.3THz. The reflectivities of liquid samples of water and ethanol are restored by the interference elimination method, which corresponds well with the theoretical calculation. Moreover, the interference elimination method is performed on THz images of fresh biological tissues. The image contrast of tissue can be greatly enhanced with the accurate reflective information.
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Pagano M, Baldacci L, Ottomaniello A, de Dato G, Chianucci F, Masini L, Carelli G, Toncelli A, Storchi P, Tredicucci A, Corona P. THz Water Transmittance and Leaf Surface Area: An Effective Nondestructive Method for Determining Leaf Water Content. SENSORS (BASEL, SWITZERLAND) 2019; 19:E4838. [PMID: 31698861 PMCID: PMC6891343 DOI: 10.3390/s19224838] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 09/28/2019] [Revised: 10/27/2019] [Accepted: 10/29/2019] [Indexed: 02/07/2023]
Abstract
Water availability is a major limiting factor in plant productivity and plays a key role in plant species distribution over a given area. New technologies, such as terahertz quantum cascade lasers (THz-QCLs) have proven to be non-invasive, effective, and accurate tools for measuring and monitoring leaf water content. This study explores the feasibility of using an advanced THz-QCL device for measuring the absolute leaf water content in Corylus avellana L., Laurus nobilis L., Ostrya carpinifolia Scop., Quercus ilex L., Quercus suber L., and Vitis vinifera L. (cv. Sangiovese). A recently proposed, simple spectroscopic technique was used, consisting in determining the transmission of the THz light beam through the leaf combined with a photographic measurement of the leaf area. A significant correlation was found between the product of the leaf optical depth (τ) and the leaf surface area (LA) with the leaf water mass (Mw) for all the studied species (Pearson's r test, p ≤ 0.05). In all cases, the best fit regression line, in the graphs of τLA as a function of Mw, displayed R2 values always greater than 0.85. The method proposed can be combined with water stress indices of plants in order to gain a better understanding of the leaf water management processes or to indirectly monitor the kinetics of leaf invasion by pathogenic bacteria, possibly leading to the development of specific models to study and fight them.
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Affiliation(s)
- Mario Pagano
- CREA—Research Centre for Plant Protection and Certification, Via di Lanciola 12/A, 50125 Firenze, Italy
- CREA—Research Centre for Viticulture and Enology, Viale Santa Margherita 80, 52100 Arezzo, Italy;
| | - Lorenzo Baldacci
- NEST, CNR—Istituto Nanoscienze and Scuola Normale Superiore, Piazza San Silvestro 12, 56124 Pisa, Italy; (L.B.); (A.O.); (L.M.); (A.T.)
| | - Andrea Ottomaniello
- NEST, CNR—Istituto Nanoscienze and Scuola Normale Superiore, Piazza San Silvestro 12, 56124 Pisa, Italy; (L.B.); (A.O.); (L.M.); (A.T.)
- Dipartimento di Fisica “E. Fermi”, Università di Pisa, Largo Bruno Pontecorvo 3, 56127 Pisa, Italy; (G.C.); (A.T.)
| | - Giovanbattista de Dato
- CREA—Research Centre for Forestry and Wood, Viale Santa Margherita 80, 52100 Arezzo, Italy; (G.d.D.); (F.C.); (P.C.)
| | - Francesco Chianucci
- CREA—Research Centre for Forestry and Wood, Viale Santa Margherita 80, 52100 Arezzo, Italy; (G.d.D.); (F.C.); (P.C.)
| | - Luca Masini
- NEST, CNR—Istituto Nanoscienze and Scuola Normale Superiore, Piazza San Silvestro 12, 56124 Pisa, Italy; (L.B.); (A.O.); (L.M.); (A.T.)
| | - Giorgio Carelli
- Dipartimento di Fisica “E. Fermi”, Università di Pisa, Largo Bruno Pontecorvo 3, 56127 Pisa, Italy; (G.C.); (A.T.)
| | - Alessandra Toncelli
- Dipartimento di Fisica “E. Fermi”, Università di Pisa, Largo Bruno Pontecorvo 3, 56127 Pisa, Italy; (G.C.); (A.T.)
| | - Paolo Storchi
- CREA—Research Centre for Viticulture and Enology, Viale Santa Margherita 80, 52100 Arezzo, Italy;
| | - Alessandro Tredicucci
- NEST, CNR—Istituto Nanoscienze and Scuola Normale Superiore, Piazza San Silvestro 12, 56124 Pisa, Italy; (L.B.); (A.O.); (L.M.); (A.T.)
- Dipartimento di Fisica “E. Fermi”, Università di Pisa, Largo Bruno Pontecorvo 3, 56127 Pisa, Italy; (G.C.); (A.T.)
| | - Piermaria Corona
- CREA—Research Centre for Forestry and Wood, Viale Santa Margherita 80, 52100 Arezzo, Italy; (G.d.D.); (F.C.); (P.C.)
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Characterization and Water Content Estimation Method of Living Plant Leaves Using Terahertz Waves. APPLIED SCIENCES-BASEL 2019. [DOI: 10.3390/app9142781] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
An increasing global aridification due to climate change has made the health monitoring of vegetation indispensable to maintaining the food supply chain. Cost-effective and smart irrigation systems are required not only to ensure the efficient distribution of water, but also to track the moisture of plant leaves, which is an important marker of the overall health of the plant. This paper presents a novel electromagnetic method to monitor the water content (WC) and characterisation in plant leaves using the absorption spectra of water molecules in the terahertz (THz) frequency for four consecutive days. We extracted the material properties of leaves of eight types of pot herbs from the scattering parameters, measured using a material characterisation kit in the frequency range of 0.75 to 1.1 THz. From the computed permittivity, it is deduced that the leaf specimens increasingly become transparent to the THz waves as they dry out with the passage of days. Moreover, the loss in weight and thickness of leaves were observed due to the natural evaporation of leaf moisture cells and change occurred in the morphology of fresh and water-stressed leaves. It is also illustrated that loss observed in WC on day 1 was in the range of 5% to 22%, and increased from 83.12% to 99.33% on day 4. Furthermore, we observed an exponential decaying trend in the peaks of the real part of the permittivity from day 1 to 4, which was reminiscent of the trend observed in the weight of all leaves. Thus, results in paper demonstrated that timely detection of water stress in leaves can help to take proactive action in relation to plants health monitoring, and for precision agriculture applications, which is of high importance to improve the overall productivity.
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Nakanishi A, Fujita K, Horita K, Takahashi H. Terahertz imaging with room-temperature terahertz difference-frequency quantum-cascade laser sources. OPTICS EXPRESS 2019; 27:1884-1893. [PMID: 30732235 DOI: 10.1364/oe.27.001884] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/23/2018] [Accepted: 12/28/2018] [Indexed: 06/09/2023]
Abstract
We demonstrate high-quality non-destructive imaging using a broadband terahertz quantum cascade laser source based on Cerenkov difference-frequency generation. The source exhibited ultra-broadband terahertz emission spectra, as well as a single-lobed Gaussian-like far-field pattern at -30 °C. These features allowed us to build a compact imaging system with a high spatial resolution, from which a nearly theoretical minimum beam spot size was obtained. As a result, we achieve well-resolved, high-contrast images of objects obscured by opaque materials. We also achieved terahertz imaging with the THz DFG-QCL operated at room temperature.
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Qu F, Lin L, He Y, Nie P, Cai C, Dong T, Pan Y, Tang Y, Luo S. Spectral Characterization and Molecular Dynamics Simulation of Pesticides Based on Terahertz Time-Domain Spectra Analyses and Density Functional Theory (DFT) Calculations. Molecules 2018; 23:molecules23071607. [PMID: 30004436 PMCID: PMC6100053 DOI: 10.3390/molecules23071607] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/25/2018] [Revised: 06/27/2018] [Accepted: 06/28/2018] [Indexed: 12/24/2022] Open
Abstract
This work provides the experimental and theoretical fundamentals for detecting the molecular fingerprints of six kinds of pesticides by using terahertz (THz) time-domain spectroscopy (THz-TDS). The spectra of absorption coefficient and refractive index of the pesticides, chlorpyrifos, fipronil, carbofuran, dimethoate, methomyl, and thidiazuron are obtained in frequencies of 0.1–3.5 THz. To accurately describe the THz spectral characteristics of pesticides, the wavelet threshold de-noising (WTD) method with db 5 wavelet fucntion, 5-layer decomposition, and soft-threshold de-noising was used to eliminate the spectral noise. The spectral baseline correction (SBC) method based on asymmetric least squares smoothing was used to remove the baseline drift. Spectral results show that chlorpyrifo had three characteristic absorption peaks at 1.47, 1.93, and 2.73 THz. Fipronil showed three peaks at 0.76, 1.23, and 2.31 THz. Carbofuran showed two peaks at 2.72 and 3.06 THz. Dimethoate showed three peaks at 1.05, 1.89, and 2.92 THz. Methomyl showed five peaks at 1.01, 1.65, 1.91, 2.72, and 3.20 THz. Thidiazuron showed four peaks at 0.99, 1.57, 2.17, and 2.66 THz. The density functional theory (DFT) of B3LYP/6-31G+(d,p) was applied to simulate the molecular dynamics for peak analyzing of the pesticides based on isolated molecules. The theoretical spectra are in good agreement with the experimental spectra processed by WTD + SBC, which implies the validity of WTD + SBC spectral processing methods and the accuracy of DFT spectral peak analysis. These results support that the combination of THz-TDS and DFT is an effective tool for pesticide fingerprint analysis and the molecular dynamics simulations.
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Affiliation(s)
- Fangfang Qu
- College of Biosystems Engineering and Food Science, Zhejiang University, Hangzhou 310058, China.
- Key Laboratory of Spectroscopy Sensing, Ministry of Agriculture, Hangzhou 310058, China.
| | - Lei Lin
- College of Biosystems Engineering and Food Science, Zhejiang University, Hangzhou 310058, China.
- Key Laboratory of Spectroscopy Sensing, Ministry of Agriculture, Hangzhou 310058, China.
| | - Yong He
- College of Biosystems Engineering and Food Science, Zhejiang University, Hangzhou 310058, China.
- Key Laboratory of Spectroscopy Sensing, Ministry of Agriculture, Hangzhou 310058, China.
| | - Pengcheng Nie
- College of Biosystems Engineering and Food Science, Zhejiang University, Hangzhou 310058, China.
- Key Laboratory of Spectroscopy Sensing, Ministry of Agriculture, Hangzhou 310058, China.
- State Key Laboratory of Modern Optical Instrumentation, Zhejiang University, Hangzhou 310027, China.
| | - Chengyong Cai
- College of Biosystems Engineering and Food Science, Zhejiang University, Hangzhou 310058, China.
- Key Laboratory of Spectroscopy Sensing, Ministry of Agriculture, Hangzhou 310058, China.
| | - Tao Dong
- College of Biosystems Engineering and Food Science, Zhejiang University, Hangzhou 310058, China.
- Key Laboratory of Spectroscopy Sensing, Ministry of Agriculture, Hangzhou 310058, China.
| | - Yi Pan
- Laser Information Technology Research Center, Harbin Institute of Technology Shenzhen Graduate School, Guangdong 518055, China.
| | - Yu Tang
- College of Automation, Zhongkai University of Agriculture and Engineering, Guangzhou 510225, China.
| | - Shaoming Luo
- College of Automation, Zhongkai University of Agriculture and Engineering, Guangzhou 510225, China.
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Baldacci L, Pagano M, Masini L, Toncelli A, Carelli G, Storchi P, Tredicucci A. Non-invasive absolute measurement of leaf water content using terahertz quantum cascade lasers. PLANT METHODS 2017; 13:51. [PMID: 28638439 PMCID: PMC5474302 DOI: 10.1186/s13007-017-0197-z] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/04/2023]
Abstract
BACKGROUND Plant water resource management is one of the main future challenges to fight recent climatic changes. The knowledge of the plant water content could be indispensable for water saving strategies. Terahertz spectroscopic techniques are particularly promising as a non-invasive tool for measuring leaf water content, thanks to the high predominance of the water contribution to the total leaf absorption. Terahertz quantum cascade lasers (THz QCL) are one of the most successful sources of THz radiation. RESULTS Here we present a new method which improves the precision of THz techniques by combining a transmission measurement performed using a THz QCL source, with simple pictures of leaves taken by an optical camera. As a proof of principle, we performed transmission measurements on six plants of Vitis vinifera L. (cv "Colorino"). We found a linear law which relates the leaf water mass to the product between the leaf optical depth in the THz and the projected area. Results are in optimal agreement with the proposed law, which reproduces the experimental data with 95% accuracy. CONCLUSIONS This method may overcome the issues related to intra-variety heterogeneities and retrieve the leaf water mass in a fast, simple, and non-invasive way. In the future this technique could highlight different behaviours in preserving the water status during drought stress.
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Affiliation(s)
- Lorenzo Baldacci
- NEST, CNR Istituto Nanoscienze and Scuola Normale Superiore, Piazza San Silvestro 12, 56127 Pisa, Italy
| | - Mario Pagano
- Consiglio per la ricerca in agricoltura e l’analisi dell’economia agraria, Centro di ricerca per la Viticoltura e l’Enologia, Viale Santa Margherita 80, 52100 Arezzo, Italy
| | - Luca Masini
- NEST, CNR Istituto Nanoscienze and Scuola Normale Superiore, Piazza San Silvestro 12, 56127 Pisa, Italy
| | - Alessandra Toncelli
- NEST, CNR Istituto Nanoscienze and Dipartimento di Fisica, Università di Pisa, Largo Pontecorvo 3, 56127 Pisa, Italy
| | - Giorgio Carelli
- Dipartimento di Fisica, Università di Pisa, Largo Pontecorvo 3, 56127 Pisa, Italy
| | - Paolo Storchi
- Consiglio per la ricerca in agricoltura e l’analisi dell’economia agraria, Centro di ricerca per la Viticoltura e l’Enologia, Viale Santa Margherita 80, 52100 Arezzo, Italy
| | - Alessandro Tredicucci
- NEST, CNR Istituto Nanoscienze and Dipartimento di Fisica, Università di Pisa, Largo Pontecorvo 3, 56127 Pisa, Italy
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Li Q, Zhou Y, Yang YF, Chen GH. 2.52 terahertz dual-axis reflection confocal scanning microscope. JOURNAL OF THE OPTICAL SOCIETY OF AMERICA. A, OPTICS, IMAGE SCIENCE, AND VISION 2016; 33:637-641. [PMID: 27140774 DOI: 10.1364/josaa.33.000637] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/05/2023]
Abstract
We present a dual-axis reflection confocal scanning microscope operating at 2.52 terahertz with axial resolution of 0.67 mm. The spatial resolution of the system was evaluated by utilizing the resolution test chart. Lateral resolution exceeded 0.314 mm, and the lengthwise resolution was over 0.353 mm. We introduced a 0.3 mm pinhole to improve the resolution. Targets such as the Chinese character "TAI" written on paper with a pencil and the metal letter "G" were scanned to test the imaging quality. To verify the imaging ability of the axial sections, two pairs of metal straps and a combinatorial metal ring were scanned, further revealing the satisfying 3D imaging capability.
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Kašalynas I, Venckevičius R, Minkevičius L, Sešek A, Wahaia F, Tamošiūnas V, Voisiat B, Seliuta D, Valušis G, Švigelj A, Trontelj J. Spectroscopic Terahertz Imaging at Room Temperature Employing Microbolometer Terahertz Sensors and Its Application to the Study of Carcinoma Tissues. SENSORS 2016; 16:432. [PMID: 27023551 PMCID: PMC4850946 DOI: 10.3390/s16040432] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 02/06/2016] [Revised: 03/04/2016] [Accepted: 03/18/2016] [Indexed: 11/16/2022]
Abstract
A terahertz (THz) imaging system based on narrow band microbolometer sensors (NBMS) and a novel diffractive lens was developed for spectroscopic microscopy applications. The frequency response characteristics of the THz antenna-coupled NBMS were determined employing Fourier transform spectroscopy. The NBMS was found to be a very sensitive frequency selective sensor which was used to develop a compact all-electronic system for multispectral THz measurements. This system was successfully applied for principal components analysis of optically opaque packed samples. A thin diffractive lens with a numerical aperture of 0.62 was proposed for the reduction of system dimensions. The THz imaging system enhanced with novel optics was used to image for the first time non-neoplastic and neoplastic human colon tissues with close to wavelength-limited spatial resolution at 584 GHz frequency. The results demonstrated the new potential of compact RT THz imaging systems in the fields of spectroscopic analysis of materials and medical diagnostics.
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Affiliation(s)
- Irmantas Kašalynas
- Department of Optoelectronics, Center for Physical Sciences and Technology, Savanoriu Ave. 231, Vilnius 02300, Lithuania.
| | - Rimvydas Venckevičius
- Department of Optoelectronics, Center for Physical Sciences and Technology, Savanoriu Ave. 231, Vilnius 02300, Lithuania.
| | - Linas Minkevičius
- Department of Optoelectronics, Center for Physical Sciences and Technology, Savanoriu Ave. 231, Vilnius 02300, Lithuania.
| | - Aleksander Sešek
- Faculty of Electrical Engineering, University of Ljubljana, Trzaska 25, Ljubljana 1000, Slovenia.
| | - Faustino Wahaia
- Instituto de Investigacao e Inovacao em Saudeand, Instituto de Engenharia Biomedica, University of Porto, Rua do Campo Alegre, 823, Porto 4150-180, Portugal.
| | - Vincas Tamošiūnas
- Department of Optoelectronics, Center for Physical Sciences and Technology, Savanoriu Ave. 231, Vilnius 02300, Lithuania.
| | - Bogdan Voisiat
- Department of Optoelectronics, Center for Physical Sciences and Technology, Savanoriu Ave. 231, Vilnius 02300, Lithuania.
| | - Dalius Seliuta
- Department of Optoelectronics, Center for Physical Sciences and Technology, Savanoriu Ave. 231, Vilnius 02300, Lithuania.
| | - Gintaras Valušis
- Department of Optoelectronics, Center for Physical Sciences and Technology, Savanoriu Ave. 231, Vilnius 02300, Lithuania.
| | - Andrej Švigelj
- Faculty of Electrical Engineering, University of Ljubljana, Trzaska 25, Ljubljana 1000, Slovenia.
| | - Janez Trontelj
- Faculty of Electrical Engineering, University of Ljubljana, Trzaska 25, Ljubljana 1000, Slovenia.
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Degl'Innocenti R, Shah YD, Jessop DS, Ren Y, Mitrofanov O, Beere HE, Ritchie DA. Hollow metallic waveguides integrated with terahertz quantum cascade lasers. OPTICS EXPRESS 2014; 22:24439-24449. [PMID: 25322020 DOI: 10.1364/oe.22.024439] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
We present the realization of a compact, monolithically integrated arrangement of terahertz quantum cascade lasers with hollow metallic cylindrical waveguides. By directly mounting a copper pipe to the end facet of a double metal waveguide, it was possible to significantly improve the far field emission from such a sub-wavelength plasmonic mode, while preserving the characteristic performance of the laser. Careful alignment of the quantum cascade laser and the hollow waveguide is required in order to prevent the excitation of higher order/mixed modes as predicted with a high degree of accuracy by a theoretical model. Finally, this approach proved to be a superior method of beam shaping when compared to other in situ arrangements, such as a silicon hyper-hemispherical lens glued to the facet, which are presented.
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13
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Charron DM, Ajito K, Kim JY, Ueno Y. Chemical Mapping of Pharmaceutical Cocrystals Using Terahertz Spectroscopic Imaging. Anal Chem 2013; 85:1980-4. [DOI: 10.1021/ac302852n] [Citation(s) in RCA: 55] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/22/2023]
Affiliation(s)
- Danielle M. Charron
- NTT Microsystem Integration Laboratories, NTT Corporation, 3-1 Morinosato Wakamiya, Atsugi, Kanagawa
243-0198 Japan
| | - Katsuhiro Ajito
- NTT Microsystem Integration Laboratories, NTT Corporation, 3-1 Morinosato Wakamiya, Atsugi, Kanagawa
243-0198 Japan
| | - Jae-Young Kim
- NTT Microsystem Integration Laboratories, NTT Corporation, 3-1 Morinosato Wakamiya, Atsugi, Kanagawa
243-0198 Japan
| | - Yuko Ueno
- NTT Microsystem Integration Laboratories, NTT Corporation, 3-1 Morinosato Wakamiya, Atsugi, Kanagawa
243-0198 Japan
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