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University of Oklahoma
1.
Islam, Shajid.
Probe-based, quasi-near-field phased array calibration.
Degree: PhD, 2020, University of Oklahoma
URL: http://hdl.handle.net/11244/326668 
► Phased array technology provides remarkable scanning flexibility and spatial search capability for the multifunction radar system, airborne radar system, and many other applications. Recent years…
(more)
▼ Phased array technology provides remarkable scanning flexibility and spatial search capability for the multifunction radar system, airborne radar system, and many other applications. Recent years have seen a noticeable surge towards low cost, small phased array antenna technology in a varied range of sectors due to its diverse applicability. However, lowering the cost exposed phased array antenna to various errors, among which excitation errors, such as incorrect phase and amplitude, is one of the major concerns. Excitation errors affect essential performance parameters such as side-lobe level, antenna gain, active impedance, and beam-forming quality. It is crucial to quantify and compensate for the errors associated with each antenna element's phase and amplitude to ensure the phased array antenna's desired performance. The process of this compensation is widely known as the calibration of a phased array. The diverse application and increased use of a low cost small phased array system make the front end calibration procedure very challenging. This challenge is two-fold. The calibration should be done accurately and quickly as possible. This dissertation focuses on developing a novel technique of phased array calibration using a fixed probe in the
quasi-
near-
field of the antenna. The objective is to significantly reduce calibration time and associated cost without compromising the calibration quality for initial and in-situ calibration. After the development of a successful mathematical framework, a detailed simulation is conducted to analyze the system. The proposed technique was finally validated using an active electronically scanned array inside a custom-made compact range and
near field range.
Advisors/Committee Members: Fulton, Caleb (advisor), Yeary, Mark (committee member), Havlicek, Joseph (committee member), Sigmarsson, Hjalti (committee member), Chavez-Dominguez, Javier (committee member).
Subjects/Keywords: Phased Array Calibration; Fast Calibration Technique; Quasi-Near-Field; Mutual Coupling
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APA (6th Edition):
Islam, S. (2020). Probe-based, quasi-near-field phased array calibration. (Doctoral Dissertation). University of Oklahoma. Retrieved from http://hdl.handle.net/11244/326668
Chicago Manual of Style (16th Edition):
Islam, Shajid. “Probe-based, quasi-near-field phased array calibration.” 2020. Doctoral Dissertation, University of Oklahoma. Accessed March 06, 2021.
http://hdl.handle.net/11244/326668.
MLA Handbook (7th Edition):
Islam, Shajid. “Probe-based, quasi-near-field phased array calibration.” 2020. Web. 06 Mar 2021.
Vancouver:
Islam S. Probe-based, quasi-near-field phased array calibration. [Internet] [Doctoral dissertation]. University of Oklahoma; 2020. [cited 2021 Mar 06].
Available from: http://hdl.handle.net/11244/326668.
Council of Science Editors:
Islam S. Probe-based, quasi-near-field phased array calibration. [Doctoral Dissertation]. University of Oklahoma; 2020. Available from: http://hdl.handle.net/11244/326668
Arizona State University
2.
Zheng, Peng.
Skin Tissue Terahertz Imaging for Fingerprint
Biometrics.
Degree: Electrical Engineering, 2017, Arizona State University
URL: http://repository.asu.edu/items/45034
► Fingerprints have been widely used as a practical method of biometrics authentication or identification with a significant level of security. However, several spoofing methods have…
(more)
▼ Fingerprints have been widely used as a practical
method of biometrics authentication or identification with a
significant level of security. However, several spoofing methods
have been used in the last few years to bypass fingerprint
scanners, thus compromising data security. The most common attacks
occur by the use of fake fingerprint during image capturing.
Imposters can build a fake fingerprint from a latent fingerprint
left on items such as glasses, doorknobs, glossy paper, etc.
Current mobile fingerprint scanning technology is incapable of
differentiating real from artificial fingers made from gelatin
molds and other materials. In this work, the adequacy of terahertz
imaging was studied as an alternative fingerprint scanning
technique that will enhance biometrics security by identifying
superficial skin traits. Terahertz waves (0.1 – 10 THz) are a
non-ionizing radiation with significant penetration depth in
several non-metallic materials. Several finger skin features, such
as valley depth and sweat ducts, can possibly be imaged by
employing the necessary imaging topology. As such, two imaging
approaches 1) using quasi-optical components and 2) using
near-field probing were investigated. The numerical study is
accomplished using a commercial Finite Element Method tool (ANSYS,
HFSS) and several laboratory experiments are conducted to evaluate
the imaging performance of the topologies. The study has shown that
terahertz waves can provide high spatial resolution images of the
skin undulations (valleys and ridges) and under certain conditions
identify the sweat duct pattern.
Subjects/Keywords: Electromagnetics; Electrical engineering; Antenna Design; Near-field Probing; Quasi-optics; Sweat Ducts; Terahertz Fingerprints Imaging
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APA (6th Edition):
Zheng, P. (2017). Skin Tissue Terahertz Imaging for Fingerprint
Biometrics. (Masters Thesis). Arizona State University. Retrieved from http://repository.asu.edu/items/45034
Chicago Manual of Style (16th Edition):
Zheng, Peng. “Skin Tissue Terahertz Imaging for Fingerprint
Biometrics.” 2017. Masters Thesis, Arizona State University. Accessed March 06, 2021.
http://repository.asu.edu/items/45034.
MLA Handbook (7th Edition):
Zheng, Peng. “Skin Tissue Terahertz Imaging for Fingerprint
Biometrics.” 2017. Web. 06 Mar 2021.
Vancouver:
Zheng P. Skin Tissue Terahertz Imaging for Fingerprint
Biometrics. [Internet] [Masters thesis]. Arizona State University; 2017. [cited 2021 Mar 06].
Available from: http://repository.asu.edu/items/45034.
Council of Science Editors:
Zheng P. Skin Tissue Terahertz Imaging for Fingerprint
Biometrics. [Masters Thesis]. Arizona State University; 2017. Available from: http://repository.asu.edu/items/45034
Delft University of Technology
3.
Chakkittakandy, R.
Quasi-near field terahertz spectroscopy.
Degree: 2010, Delft University of Technology
URL: http://resolver.tudelft.nl/uuid:8a400e6c-117e-495d-99fc-2acac2084139
;
urn:NBN:nl:ui:24-uuid:8a400e6c-117e-495d-99fc-2acac2084139
;
urn:NBN:nl:ui:24-uuid:8a400e6c-117e-495d-99fc-2acac2084139
;
http://resolver.tudelft.nl/uuid:8a400e6c-117e-495d-99fc-2acac2084139
► Everyday we see around us many materials that are different from one another. We identify them on the basis of their shape, texture, smell, taste,…
(more)
▼ Everyday we see around us many materials that are different from one another. We identify them on the basis of their shape, texture, smell, taste, color, etc with the help of our senses. Many times it is almost impossible to identify materials only with our senses. Then, one has to look into more fundamental aspects of the materials such as their atomic or molecular constituents. Different techniques exist to identify and characterize materials. Spectroscopy is one such technique. Spectroscopy relies on the frequency selective emission or absorption of electromagnetic radiation by the materials to get information about their physical/chemical properties. There are different spectroscopic techniques to study materials and their interaction with electromagnetic radiation. Terahertz (THz) radiation is the part of electromagnetic spectrum, which lies between the microwave and infrared regions of the electromagnetic spectrum. It is loosely defined as the frequency range from 0.1 to 10 THz. Terahertz radiation can penetrate a wide range of materials: paper, wood, plastics, fabric, ceramics, semiconductors, and many others that are often opaque to visible and
near-infrared (NIR) radiation. Many materials have characteristic absorption bands in the THz region. Thus, in THz imaging applications, apart from getting a THz image, the measurement can also give spectroscopic information on the samples under study, which can be used to identify the materials. In principle, this spectroscopic imaging makes it possible to identify the contents inside a package without even opening it. There exist various techniques to generate terahertz (THz) radiation. In photo-conductive antennas (PCAs), a time-dependent polarization is formed when charge carriers, created by a femtosecond laser pulse, are accelerated in an externally applied electric
field. PCAs are capable of generating broadband pulses with a fairly high power. The THz generation and detection setup with the photo-conductive antenna as the THz source and electro-optic sampling as the THz detector as described in Chapter 2 gives a very high SNR of ?15000 in a measurement time of 10 ms. Even though our femtosecond laser pulses have a very high peak power, the generated THz power could not be increased further with increasing laser pump power on the emitter, because of emitter saturation. Increasing the laser spot size on the emitter gives a higher THz peak power than in the case of a tightly focused pump beam. Among the different techniques to generate THz radiation, the technique using the optical conversion of extremely short pulses of light into THz pulses at a high repetition rate is very popular. These short laser pulses are partially converted into THz light in certain non-linear optical media. By using coherent detection techniques, the amplitude and phase of the THz pulse can be detected in the time domain. This spectroscopic technique is called terahertz time domain spectroscopy (THz-TDS). A typical THz-TDS setup has a long THz beam path. Atmospheric water vapor, present…
Advisors/Committee Members: Planken, P.C.M..
Subjects/Keywords: terahertz; spectroscopy; polymorphs; mannitol; amino acids; quasi-near field
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APA (6th Edition):
Chakkittakandy, R. (2010). Quasi-near field terahertz spectroscopy. (Doctoral Dissertation). Delft University of Technology. Retrieved from http://resolver.tudelft.nl/uuid:8a400e6c-117e-495d-99fc-2acac2084139 ; urn:NBN:nl:ui:24-uuid:8a400e6c-117e-495d-99fc-2acac2084139 ; urn:NBN:nl:ui:24-uuid:8a400e6c-117e-495d-99fc-2acac2084139 ; http://resolver.tudelft.nl/uuid:8a400e6c-117e-495d-99fc-2acac2084139
Chicago Manual of Style (16th Edition):
Chakkittakandy, R. “Quasi-near field terahertz spectroscopy.” 2010. Doctoral Dissertation, Delft University of Technology. Accessed March 06, 2021.
http://resolver.tudelft.nl/uuid:8a400e6c-117e-495d-99fc-2acac2084139 ; urn:NBN:nl:ui:24-uuid:8a400e6c-117e-495d-99fc-2acac2084139 ; urn:NBN:nl:ui:24-uuid:8a400e6c-117e-495d-99fc-2acac2084139 ; http://resolver.tudelft.nl/uuid:8a400e6c-117e-495d-99fc-2acac2084139.
MLA Handbook (7th Edition):
Chakkittakandy, R. “Quasi-near field terahertz spectroscopy.” 2010. Web. 06 Mar 2021.
Vancouver:
Chakkittakandy R. Quasi-near field terahertz spectroscopy. [Internet] [Doctoral dissertation]. Delft University of Technology; 2010. [cited 2021 Mar 06].
Available from: http://resolver.tudelft.nl/uuid:8a400e6c-117e-495d-99fc-2acac2084139 ; urn:NBN:nl:ui:24-uuid:8a400e6c-117e-495d-99fc-2acac2084139 ; urn:NBN:nl:ui:24-uuid:8a400e6c-117e-495d-99fc-2acac2084139 ; http://resolver.tudelft.nl/uuid:8a400e6c-117e-495d-99fc-2acac2084139.
Council of Science Editors:
Chakkittakandy R. Quasi-near field terahertz spectroscopy. [Doctoral Dissertation]. Delft University of Technology; 2010. Available from: http://resolver.tudelft.nl/uuid:8a400e6c-117e-495d-99fc-2acac2084139 ; urn:NBN:nl:ui:24-uuid:8a400e6c-117e-495d-99fc-2acac2084139 ; urn:NBN:nl:ui:24-uuid:8a400e6c-117e-495d-99fc-2acac2084139 ; http://resolver.tudelft.nl/uuid:8a400e6c-117e-495d-99fc-2acac2084139
Macquarie University
4.
Stecher, Matthias.
THz generation and devices: design, fabrication and characterization.
Degree: PhD, 2011, Macquarie University
URL: http://hdl.handle.net/1959.14/192192
► This thesis is presented for the degree of Doctor of Philosophy, Macquarie University, Faculty of Science, Dept. of Electronic Engineering and Technische Universität Carolo-Wilhelmina zu…
(more)
▼ This thesis is presented for the degree of Doctor of Philosophy, Macquarie University, Faculty of Science, Dept. of Electronic Engineering and Technische Universität Carolo-Wilhelmina zu Braunschweig (Germany), Dept. of Electrical Engineering, Information Technology, Physics, Institute for High-Frequency Technology, 2011.
Bibliography: p. [87]-94.
Introduction – Fundamentals of THz time domain and continuous wave systems – THz near-field imaging of polymer THz fibers – Novel polymer based THz filters – THz generation from multi-frequency laser radiation – Summary.
The THz frequency band (0.1 - 10 THz) is located in between the well explored optical frequencies and the microwave band. Despite growing research efforts in the last two decades, THz sensing systems are far from robust and cost effective. The development of passive devices for THz applications like waveguides, filters, reflectors and modulators is in the beginning of being established. This work contributes to the field by introducing novel polymer filter structures and a new design of THz fibers. These passive devices are fabricated by using a fiber drawing technique to scale down inscribed patterns in polymer to the THz wavelengths. Moreover, the revolutionary quasi time-domain spectrometer approach is further extended to suit varying sensing applications. – This work is structured in four chapters. The first chapter describes THz fundamentals and state-of-the-art THz systems for common time-domain (TDS) and continuous wave (CW) spectrometers. The generation and detection principles are discussed in detail and typical system designs are presented. – In the second chapter the fabrication and design process of polymer photonic crystal THz waveguides is presented. An improved near-field THz TDS system is introduced to verify the mode distributions. In addition, a new approach for improving the confinement and stripping of undesired higher order modes is demonstrated. – Chapter three presents a new polymer filter structure. The fabrication process scales down inscribed features in a polymer preform by fiber drawing. Thus it is possible to obtain hole diameters of 200 μm and below, which could not be mechanically fabricated. The structures are first simulated and afterwards analyzed by a standard THz TDS system. – The last chapter is based on the novel quasi time-domain spectrometer approach introduced by Scheller in 2009 [Optics Express, Vol. 17, Issue 20]. The CW based generation and detection scheme is presented and in cooperation with the author, a hybrid THz spectrometer and imaging capability is demonstrated. A second system approach - a dual QTDS spectrometer - is set up, demonstrating that QTDS has the potential for customized low-cost and robust THz systems.
x, 122 p. ill. (some col.)
Advisors/Committee Members: Macquarie University. Department of Engineering.
Subjects/Keywords: Terahertz technology; Wave guides; Photonic crystals; Spectrometer; Terahertz; THz filter; THz near field; THz quasi time domain
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APA ·
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APA (6th Edition):
Stecher, M. (2011). THz generation and devices: design, fabrication and characterization. (Doctoral Dissertation). Macquarie University. Retrieved from http://hdl.handle.net/1959.14/192192
Chicago Manual of Style (16th Edition):
Stecher, Matthias. “THz generation and devices: design, fabrication and characterization.” 2011. Doctoral Dissertation, Macquarie University. Accessed March 06, 2021.
http://hdl.handle.net/1959.14/192192.
MLA Handbook (7th Edition):
Stecher, Matthias. “THz generation and devices: design, fabrication and characterization.” 2011. Web. 06 Mar 2021.
Vancouver:
Stecher M. THz generation and devices: design, fabrication and characterization. [Internet] [Doctoral dissertation]. Macquarie University; 2011. [cited 2021 Mar 06].
Available from: http://hdl.handle.net/1959.14/192192.
Council of Science Editors:
Stecher M. THz generation and devices: design, fabrication and characterization. [Doctoral Dissertation]. Macquarie University; 2011. Available from: http://hdl.handle.net/1959.14/192192
5.
Nasreddine, Rouba.
Développement d'une méthode analytique et d'un microanalyseur miniaturisé pour la détection des BTEX dans l'air : Development of an analytical method and a miniaturized analyzer to detect BTEX in air.
Degree: Docteur es, Chimie analytique, 2016, Université de Strasbourg
URL: http://www.theses.fr/2016STRAF010
► Les BTEX est une famille de polluants très répandue en air intérieur. Ils présentent des effets nocifs sur la santé humaine à des faibles concentrations…
(more)
▼ Les BTEX est une famille de polluants très répandue en air intérieur. Ils présentent des effets nocifs sur la santé humaine à des faibles concentrations ce qui a emmené le législateur à fixer des seuils afin de limiter l'exposition des gens. L'objectif de ce travail de recherche est de développer et de mettre en place une méthode analytique sensible, précise et rapide basée sur un dispositif de mesure. Le dispositif ainsi mis en place est un chromatographe en phase gazeuse miniaturisé équipé d'un mini détecteur à photo ionisation dédié à la détection des BTEX en temps quasi-réel. Le système analytique est très portable ayant une consommation gazeuse très faible assurant une autonomie élevée sur de longues durées. Son mode de fonctionnement se base sur l'échantillonnage de l'air dans une boucle connecté à une vanne six voies. L'injection de l'échantillon sur une colonne analytique placée dans un four pour la séparation est assurée par le changement de la position de la vanne avant la détection par photo ionisation. Le nouveau dispositif miniaturisé a été déployé lors de deux campagnes intensives menées dans un collège énergétiquement performant. Cette étude a porté sur la surveillance temporelle de la concentration des polluants présents en air intérieur, y compris les BTEX. Les résultats ainsi obtenus pour les BTEX avec notre dispositif ont été comparés à ceux fournis par d'autres techniques dites techniques de référence. Ces campagnes de terrain ont permis donc de valider les performances analytiques, la robustesse et l'autonomie de cette nouvelle méthodologie.
BTEX are very widespread indoor air pollutants. Their harmful effects on human health had led the legislator to set thresholds in order to limit the population exposure. The aim of this thesis is to develop a sensitive, accurate and fast analytical method based on a measurement device. Therefore, the device implemented is a miniaturized gas chromatography (GC) equipped with a mini photo ionization detector dedicated to BTEX detection in indoor air in near-real time. The miniaturized GC is very portable with a very low gas consumption which enhances its autonomy over a long period. Its operation mode is based on air sampling inside a sample loop which is connected to a six port valve. The injection over a heated analytical column is ensured by switching the valve position before detection by a photo ionization detector. This novel device was used in real conditions during two field campaigns conducted in an energy efficient college. This study focused on the temporal monitoring of indoor air pollutant concentrations including BTEX. The results obtained with our miniaturized device for BTEX were compared to those given by other techniques known as reference techniques. These field campaigns have therefore enabled us to validate the analytical performances, the robustness and the autonomy of this novel analytical method.
Advisors/Committee Members: Le Calvé, Stéphane (thesis director), Serra, Christophe (thesis director).
Subjects/Keywords: BTEX; Méthode analytique; Chromatographie gazeuse; , détecteur à photo ionisation; Détection en temps quasi-réel; Qualité de l'air intérieur; Campagne de terrain; BTEX; Analytical method; Gas chromatography; Photo ionization detector; Near-real time detection; Indoor air quality; Field measurements; 543
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APA ·
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APA (6th Edition):
Nasreddine, R. (2016). Développement d'une méthode analytique et d'un microanalyseur miniaturisé pour la détection des BTEX dans l'air : Development of an analytical method and a miniaturized analyzer to detect BTEX in air. (Doctoral Dissertation). Université de Strasbourg. Retrieved from http://www.theses.fr/2016STRAF010
Chicago Manual of Style (16th Edition):
Nasreddine, Rouba. “Développement d'une méthode analytique et d'un microanalyseur miniaturisé pour la détection des BTEX dans l'air : Development of an analytical method and a miniaturized analyzer to detect BTEX in air.” 2016. Doctoral Dissertation, Université de Strasbourg. Accessed March 06, 2021.
http://www.theses.fr/2016STRAF010.
MLA Handbook (7th Edition):
Nasreddine, Rouba. “Développement d'une méthode analytique et d'un microanalyseur miniaturisé pour la détection des BTEX dans l'air : Development of an analytical method and a miniaturized analyzer to detect BTEX in air.” 2016. Web. 06 Mar 2021.
Vancouver:
Nasreddine R. Développement d'une méthode analytique et d'un microanalyseur miniaturisé pour la détection des BTEX dans l'air : Development of an analytical method and a miniaturized analyzer to detect BTEX in air. [Internet] [Doctoral dissertation]. Université de Strasbourg; 2016. [cited 2021 Mar 06].
Available from: http://www.theses.fr/2016STRAF010.
Council of Science Editors:
Nasreddine R. Développement d'une méthode analytique et d'un microanalyseur miniaturisé pour la détection des BTEX dans l'air : Development of an analytical method and a miniaturized analyzer to detect BTEX in air. [Doctoral Dissertation]. Université de Strasbourg; 2016. Available from: http://www.theses.fr/2016STRAF010
ETH Zürich
6.
Achermann, Marc.
Ultrafast goes local.
Degree: 2001, ETH Zürich
URL: http://hdl.handle.net/20.500.11850/145519
Subjects/Keywords: OPTISCHE NAHFELDMIKROSKOPIE (OPTIK); LASERPULS, KURZZEITPHÄNOMENE (LASERTECHNIK); TRANSPORTPROZESSE, TRANSPORTPHÄNOMENE (PHYSIK DER KONDENSIERTEN MATERIE); SCHOTTKY-DIODEN (ELEKTRONIK); EINDIMENSIONALE, QUASI-EINDIMENSIONALE STRUKTUR (PHYSIK DER KONDENSIERTEN MATERIE); NEAR-FIELD OPTICAL MICROSCOPY (OPTICS); LASER PULSES, SHORT-TIME PHENOMENA (LASER ENGINEERING); TRANSPORT PROCESSES, TRANSPORT PHENOMENA (CONDENSED MATTER PHYSICS); SCHOTTKY DIODES (ELECTRONICS); ONE-DIMENSIONAL, QUASI ONE-DIMENSIONAL STRUCTURE (CONDENSED MATTER PHYSICS); info:eu-repo/classification/ddc/530; Physics
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APA ·
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APA (6th Edition):
Achermann, M. (2001). Ultrafast goes local. (Doctoral Dissertation). ETH Zürich. Retrieved from http://hdl.handle.net/20.500.11850/145519
Chicago Manual of Style (16th Edition):
Achermann, Marc. “Ultrafast goes local.” 2001. Doctoral Dissertation, ETH Zürich. Accessed March 06, 2021.
http://hdl.handle.net/20.500.11850/145519.
MLA Handbook (7th Edition):
Achermann, Marc. “Ultrafast goes local.” 2001. Web. 06 Mar 2021.
Vancouver:
Achermann M. Ultrafast goes local. [Internet] [Doctoral dissertation]. ETH Zürich; 2001. [cited 2021 Mar 06].
Available from: http://hdl.handle.net/20.500.11850/145519.
Council of Science Editors:
Achermann M. Ultrafast goes local. [Doctoral Dissertation]. ETH Zürich; 2001. Available from: http://hdl.handle.net/20.500.11850/145519
. 
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